Stability of Timber Bridges Subject to Scour 
 
by 
 
Mary Eudora Schambeau 
 
 
 
 
A thesis submitted to the Graduate Faculty of 
Auburn University 
in partial fulfillment of the 
requirements for the Degree of 
Master of Science in Civil Engineering 
 
Auburn, Alabama 
August 4, 2012 
 
 
 
 
Keywords:  scour, timber, bridges, structural health monitoring 
 
Copyright 2012 by Mary Eudora Schambeau 
 
 
Approved by 
 
James S. Davidson, Ph.D., Associate Professor of Civil Engineering 
Mary L. Hughes, Ph.D., Instructor of Civil Engineering 
G. Ed Ramey, Ph.D., Professor Emeritus of Civil Engineering 
Justin D. Marshall, Ph.D., Assistant Professor of Civil Engineering 
 ii
 
 
 
 
 
 
ABSTRACT 
 
 
 Because scour is responsible for most disastrous bridge failures, bridge scour 
monitoring is necessary for the safety of public roads.  While much attention is paid to 
the amount of bridge scour at a foundation, the structural stability implications of the 
loss of embedment due to scour are not easily assessed.  To fill this need, an 
automated screening tool for the evaluation of timber pile bents was developed.  The 
tool examines five failure modes of timber piles and timber bents:  kick-out of a bent due 
to zero or negligible embedment after scour; pile plunging due to soil failure; pile 
buckling failure in either the longitudinal or transverse direction; bent pushover failure 
due to the combined effects of superstructure gravity loading and loading from the 
lateral debris raft load; and beam-column failure of the upstream pile due to the 
combined lateral debris raft load and axial gravity loading.  The automated screening 
tool was programmed using Visual Studio 2005 and 2010 software package.  A series 
of forms allow the user to input bent geometry and scour conditions for the bent under 
assessment, then the program will internally evaluates the structural stability.  A 
printable report is also provided to supply documentation of the stability analyses. 
 
 iii 
 
 
 
 
 
 
ACKNOWLEDGEMENTS 
 
 
 I would like to thank my advisors, Dr. Davidson, Dr. Hughes, and Dr. Ramey for 
all their help on this project.  Without their experience, this work could not have been 
completed.  As this research was prepared under cooperative agreement between the 
Alabama Department of Transportation (ALDOT) and the Highway Research Center 
(HRC) at Auburn University, I am grateful to the ALDOT and HRC for their sponsorship 
and support of the work in addition to the assistance and guidance of several ALDOT 
engineers during the execution of the research work.  Specifically, thanks are due to 
James Bearrentine, Eric Christie, George Connor, and Ashley Mock of ALDOT.  Also, 
this work could not have been completed without assistance from members of 
Engineering Network Services, specifically Nabeel Rawajfih and Jamie Jones. 
   
 
iv 
 
 
 
 
 
 
TABLE OF CONTENTS 
 
 
Abstract ......................................................................................................................... ii 
Acknowledgments  ........................................................................................................ iii 
List of Tables ................................................................................................................ vii 
List of Figures ................................................................................................................ x 
List of Nomenclature ................................................................................................... xiii 
Chapter 1 Introduction ................................................................................................... 1 
 1.1 Problem Statement  ...................................................................................... 1 
 1.2 Research Objective   .................................................................................... 2 
 1.3 Work Plan   ................................................................................................... 5 
Chapter 2 Literature Review .......................................................................................... 4 
 2.1 National Bridge Inspection Standards   ........................................................ 4 
 2.2 Scour Failure of Bridges   ............................................................................. 6 
 2.3 Scour Monitoring Practices   ......................................................................... 8 
 2.4 Structural Analysis of Scour Critical Bridges  .............................................. 11  
 2.5 Material Properties of Timber Piles   ........................................................... 15 
 2.6 Review of Visual Studio and Visual Basic Code Writing (VBA)  ................. 21 
Chapter 3 Scour Monitoring of Country Bridges Supported on Timber Pile Bents ...... 22 
 3.1 General   ..................................................................................................... 22 
 3.2 Bridge Parameter Values Needed to Assess Bridge Stability   ................... 24 
 
v 
 
 3.3 Possible Failure Modes of Timber Pile Bents   ........................................... 24 
 3.4 Typical Value Ranges of Alabama County Bridges  ................................... 25  
 3.5 Material Assumption Used in Screening Tool   ........................................... 27 
 3.6 Debris Raft Consideration for Small Span Bridges  .................................... 30 
Chapter 4 Failure Modes for Timber Bents Subject to Scour ...................................... 33 
 4.1 General   ..................................................................................................... 33 
 4.2 Kick-out Failure   ......................................................................................... 33 
 4.3 Pile Plunging by Soil Failure   ..................................................................... 35 
 4.4 Bent Pile Buckling Failure  .......................................................................... 46  
 4.5 Bent Pushover Failure   .............................................................................. 59 
 4.6 Beam-Column Failure  ................................................................................ 72 
Chapter 5 Screening Tool Flowcharts ......................................................................... 80 
 5.1 General   ..................................................................................................... 80 
 5.2 Screening Tool Macro-Flowchart   .............................................................. 80 
 5.3 Screening Tool Micro-Flowcharts   ............................................................. 82 
Chapter 6 Automation of the Screening Tool Using Visual Studio .............................. 89 
 6.1 General   ..................................................................................................... 89 
 6.2 Preliminary Input Analysis   ........................................................................ 92 
 6.3 Kick-out and Plunging Analysis   ................................................................ 97 
 6.4 Buckling Evaluation  ................................................................................. 103  
 6.5 Pushover Evaluation  ................................................................................ 105 
 6.6 Beam-Column Evaluation  ........................................................................ 108  
 6.7 Conclusions and Output Report  ............................................................... 109 
 
vi 
 
 
Chapter 7 Automatic Screening Tool Post-Analyses ................................................. 115 
 7.1 General   ................................................................................................... 115 
 7.2 Buckling Post-Analyses   .......................................................................... 115 
 7.3 Plunging Post-Analysis   ........................................................................... 133 
 7.4 Bent Pushover Post-Analyses  ................................................................. 139  
 7.5 Beam-Column Post-Analyses  .................................................................. 141 
Chapter 8 Conclusions   ............................................................................................ 143 
References   .............................................................................................................. 146 
Appendix A:  X-Braced Timber Pile Bent (
?
 vs. ? Pushover Curves.......................... 150 
Appendix B:  Unbraced Timber Pile Bent (
?
 vs. ? Pushover Curves  ........................ 224 
Appendix C:  Beam Column Analyses ....................................................................... 279 
Appendix D:  Automated Screening Tool Visual Basic Code .................................... 296 
 
 
 
 
 vii
 
 
 
 
 
 
LIST OF TABLES 
 
 
Table 2.1 Critical Ratings for Item 113 of SI&A Guide: Scour Critical Bridges  
 (FHWA 1995) ................................................................................................ 6 
Table 2.2 Typical Limiting Dimensions for Piles, Inches (Chellis 1961)....................... 16 
Table 2.3 Approximate Elastic Modulus and Strengths of Woods Commonly 
                Used for Timber Piles in Alabama (Chellis 1961) ........................................ 18 
Table 2.4 Load Duration Modification Factors for Timber (Schaeffer 1980) ................ 18 
Table 2.5 Timber Pile Material Properties Used in Screening Tool ............................. 19 
Table 2.6 Geometric Properties of Select Timber Utility Poles (Quintero 1980) .......... 20 
Table 3.1 Timber Pile Material Properties Used in Screening Tool ............................. 28 
Table 3.2 Typical Effective Section Properties for Common Pile Sizes ....................... 30 
Table 4.1 Common Driving Resistance Ranges (Bowles 1968) .................................. 38 
Table 4.2 Estimated Hammer Efficiencies ................................................................... 38 
Table 4.3 Predicted Pile Capacities Based on Modified Gates Formula for Timber 
                Piles with F.S. = 1.25 ................................................................................... 43 
Table 4.4 Assumed Fixity Conditions Based on Embedment Length .......................... 47 
Table 4.5 Critical Longitudinal Buckling Lengths and Critical Scour for Various 
                Bent Parameters (E = 1,800 ksi, F.S. = 1.33) .............................................. 51 
Table 4.6 Critical Transverse Sidesway Buckling Lengths and Critical Scour for  
                Various Braced Bent Parameters (E = 1,800 ksi, F.S. = 1.33) .................... 56 
 viii
Table 4.7 Critical Transverse Sidesway Buckling Lengths and Critical Scour for  
                Various Unbraced Bent Parameters (E = 1,800 ksi, F.S. = 1.33) ................ 58 
Table 4.8 Equations for Buckling for Braced and Unbraced Bents .............................. 59  
Table 4.9 Timber Pile Bent Cases Analyzed for Pushover .......................................... 65 
Table 4.10 Pushover Loads F
t
 for Braced, 12? Pile Butt Diameter Bents .................... 66 
Table 4.11 Pushover Loads F
t
 for Braced, 14? Pile Butt Diameter Bents .................... 68 
Table 4.12 Pushover Loads F
t
 for Unbraced, 12? Pile Butt Diameter Bents ................ 70 
Table 4.13 Pushover Loads F
t
 for Unbraced, 14? Pile Butt Diameter Bents ................ 71 
Table 4.14 Beam-Column Analysis Evaluations for Multiple Bent Geometries ........... 78 
Table 7.1 Critical Transverse Sidesway Buckling Lengths and Scour Depths for 
                Braced Bents, 12 in. Pile Butt Diameter, 20 ft Pile Embedment ................ 116 
Table 7.2 Critical Scour Values for Transverse and Longitudinal Buckling for 
                Braced Bents, 12 in. Pile Butt Diameter, 20 ft Pile Embedment ................ 117 
Table 7.3 Corresponding Allowable Loads based on Critical Scour for Braced 
                Bents, 12 in. Pile Butt Diameter, 20 ft Pile Embedment ............................ 119 
Table 7.4 Difference in Effective Moment of Inertia Based on Buckling Mode .......... 120 
Table 7.5 Critical Bent Heights for Longitudinal Buckling Control ............................. 122 
Table 7.6 Critical Scour Values for Transverse and Longitudinal Buckling for 
                Braced Bents, 12 in Pile Butt Diameter, 18 ft Pile Embedment ................. 125 
Table 7.7 Corresponding Allowable Loads based on Critical Scour for Braced 
                Bents, 12 in. Pile Butt Diameter, 18 ft Pile Embedment ............................ 126 
Table 7.8 Critical Scour Depths for Buckling for Braced and Unbraced Bents 
                (16 ft Bent Height, 14 in. Pile Butt Diameter, 20 ft Pile Embedment) ......... 128 
 ix
Table 7.9 Effective Moment of Inertia for Varying Scour Depths ............................... 129 
Table 7.10 Critical Scour Depths for Buckling for Braced Bent (20 ft Bent Height, 
                  12 in. Pile Butt Diameter, 20 ft Pile Embedment ...................................... 131 
Table 7.11 Iteration Example for Most Conservative Critical Scour Depth (14 ft Bent 
Height, 12 in. Pile Butt Diameter, 30 ft Pile Embedment, 50 kip P-Load, 
Braced Bent)  ........................................................................................... 133 
Table 7.12 Pile Plunging Capacities and Critical Scours for Plunging Failure 
                 (4 bpi Driving Resistance, 13,000 lb-ft Drop Hammer,  
                 20 ft Pile Embedment) .............................................................................. 134 
Table 7.13 Pile Plunging Capacities and Critical Scours for Plunging Failure 
                 (5 bpi Driving Resistance, 13,000 lb-ft Drop Hammer,  
                 20 ft Pile Embedment) .............................................................................. 136 
Table 7.14 Pile Plunging Capacities and Critical Scours for Plunging Failure 
                 (5 bpi Driving Resistance, 13,000 lb-ft Drop Hammer,  
                 15 ft Pile Embedment) .............................................................................. 137 
Table 7.15 Pile Plunging Capacities and Critical Scours for Plunging Failure 
                 (5 bpi Driving Resistance, 13,000 lb-ft Diesel Hammer,  
                 15 ft Pile Embedment) .............................................................................. 138 
Table 7.16 Percent Increase in Plunging Capacity Based on Hammer Efficiency ..... 138 
Table 7.17 Pushover Forces for 4-pile Unbraced Steel and Timber Bents, kips ....... 140 
Table 7.18 Bent Pushover Forces for Unbraced 4-pile  Steel Bent, kips ...... 141 
Table 7.19 Allowable Scour Depths and Allowable Loads for Beam-Column  
                  Evaluation for Braced Timber Bents and Large Debris Rafts .................. 142 
 
 x
 
 
 
 
 
 
LIST OF FIGURES 
 
Figure 2.1 Plan and Elevation View of Local Scour (Maddison 2012) ........................... 7  
Figure 2.2 Typical Timber Pile (Quintero 1980) ........................................................... 15 
Figure 3.1 Typical Timber Pile Bents (provided by ALDOT) ........................................ 22 
Figure 3.2 Transverse Section of Typical Timber Bridges with Information Needed                   
to Assess Adequacy During an Extreme Scour Event ............................... 24 
Figure 3.3 Alabama County Timber Pile Bent Ranges of Critical Assessment 
Parameters ................................................................................................ 27  
Figure 3.4 Effective Section of Embedded Timber Pile (Ramey et al. 2011) ............... 28 
Figure 3.5 Variation of Pile Effective Moment of Inertia versus Pile Diameter ............. 29 
Figure 3.6 Debris Raft Force Calculation for Small Span Bridges ............................... 32 
Figure 4.1 Pile Tip Kick-out Failure ............................................................................. 34 
Figure 4.2 Pile Axial Resistance .................................................................................. 36 
Figure 4.3 Elevations Schematics of Timber and Steel Wide Flange Piles ................. 37 
Figure 4.4 Plunging Capacity Curves for 12,000 k-ft Driving Energy, 4 bpi Driving 
Resistance by Modified Gates Formula ..................................................... 44 
Figure 4.5 Buckled Shape and Coordinate Axes ......................................................... 46 
Figure 4.6 Longitudinal Buckling Failure Mode for Braced and Unbraced Bents ........ 49 
 
Figure 4.7 Critical Scour ( ) versus Bent Height (H) for Longitudinal Buckling for 
 
 xi
                 Timber Pile Bent (F.S. = 1.33) .................................................................... 52 
Figure 4.8 Buckling in the Transverse Directions for Braced Bents ............................ 53 
Figure 4.9 Critical Buckling Lengths for Braced Bents over Water .............................. 54 
Figure 4.10 Sidesway Buckling of Unbraced Timber Bents ......................................... 57 
Figure 4.11 Stress-Strain Curve for Nonlinear Pushover of Timber Bents .................. 60 
Figure 4.12 Typical Braced Bent Pushover Failure ..................................................... 61 
Figure 4.13 Critical Debris Raft Location for Pushover Failure .................................... 62 
Figure 4.14 Bent Pushover Curve for 3-pile, 12 ft Bent Height, 14 in. Pile Butt Diameter, 
20 kip P-Load, and No Scour ..................................................................... 64 
Figure 4.15 Beam-Column Failure for Typical Braced Bent ........................................ 72 
Figure 4.16 Assumed Ultimate and Allowable Load Interaction Equations ................. 73 
Figure 4.17 Beam-Column Analysis for 3-Pile Braced Bent (Bent Height = 12 ft, 
                    Scour = 20 ft, Pile Butt Diameter = 12 in.) ............................................... 77 
Figure 5.1 Screening Tool (ST) Macro-Flowchart ....................................................... 81 
Figure 5.2 Screening Tool (ST) Micro-Flowchart Schematic ....................................... 83 
Figure 5.3 Screening Tool Flowchart Block 1 ? Preliminary Evaluation ...................... 84 
Figure 5.4 Screening Tool Flowchart Block 2 ? Kick-out and Plunging Evaluation ..... 85 
Figure 5.5 Screening Tool Flowchart Block 3 ? Buckling Evaluation ........................... 86 
Figure 5.6 Screening Tool Flowchart Block 4 ? Bent Pushover Evaluation ................. 87 
Figure 5.7 Screening Tool Flowchart Block 5 ? Beam-Column Evaluation ................. 88 
Figure 6.1 Opening Form for Timber Stability Tool ..................................................... 90 
Figure 6.2 General Help Dialog Box ............................................................................ 91 
Figure 6.3 Preliminary Evaluation Form ...................................................................... 93 
 
 xii
Figure 6.4 Preliminary Evaluation Help Dialog Box ..................................................... 94 
Figure 6.5 Example Critical Section Loss Alert Dialog Box ......................................... 95 
Figure 6.6 Input Form for Maximum Pile and Bent Loads ........................................... 96 
Figure 6.7 Pile and Bent Applied Loads Help Dialog Box ............................................ 97 
Figure 6.8 Plunging Evaluation Form Showing Input .................................................. 98 
Figure 6.9 Plunging Help Dialog Box........................................................................... 99 
Figure 6.10 Kick-out Evaluation Dialog Box for All Piles Safe ................................... 100 
Figure 6.11 Kick-out Evaluation Dialog Box for Certain Piles Unsafe ....................... 101 
Figure 6.12 Plunging Evaluation Form Showing Input and Output ............................ 102 
Figure 6.13 Buckling Evaluation Form ....................................................................... 104 
Figure 6.14 Bent Pushover Evaluation Form ............................................................. 106 
Figure 6.15 Beam-Column Evaluation Form ............................................................. 108 
Figure 6.16 Final Conclusions Form.......................................................................... 109 
Figure 6.17 Conclusions and Printing Help Dialog Box ............................................. 110 
Figure 6.18 Printing Form .......................................................................................... 111 
Figure 6.19 Print Preview of Printable Output Report................................................ 112 
Figure 6.20 Example Output Report (Page 1 of 2) .................................................... 113 
Figure 6.21 Example Output Report (Page 2 of 2) .................................................... 114 
Figure 7.1 Estimated Scour Effect on Effective Section Selection ............................ 130 
 
 xiii
 
 
 
 
 
 
LIST OF NOMENCLATURE 
 
 
ALDOT Alabama Department of Transportation    
bpi blows per inch 
C buckling coefficient 
%
?
 drag coefficient 
@
????
  pile diameter at butt location, inches 
@
???
  pile diameter at effective section location, inches 
@
???
  pile diameter at tip location, inches 
@
?
  depth of water under bent, feet 
E modulus of elasticity (Young?s modulus), ksi 
F.S. factor of safety 
(
?
 lateral debris raft force or pushover force, kips 
ft feet  
ft-lb foot-pound  
FHWA Federal Highway Administration 
H bent height from top of cap to the new ground line, feet    
HB horizontal brace 
HWL high water line during flood event 
+
???
 moment of inertia of effective section, in??
+
???
?
 effective moment of inertia for longitudinal buckling of braced bent, in? 
 xiv
+
???
?
 effective moment of inertia for transverse buckling of braced bent, in??
in. inch 
k-ft kip-feet 
ksi kips per square inch 
L total pile length including embedment below ground line, feet 
H
??
  critical buckling length that will cause failure, feet 
.
??
  length of pile above ground after scour event (from pile cap to NGL), feet 
.
??
  length of pile below ground after scour event (from NGL to pile tip), feet 
.
??
  length of pile below ground before scour event (from OGL to pile tip), feet 
/
???
  maximum moment on pile, k-ft 
/
???????
  moment that will cause rupture of the pile, k-ft 
NBIS National Bridge Inventory System 
NGL new ground line elevation after scour event 
OGL original ground line elevation before scour event 
P gravity concentrated load on pile from superstructure, kips 
2
?????????
  gravity concentrated load pile can carry without failure, kips 
2
??
  critical gravity concentrated load that will cause failure, kips or tons 
2
??
?
  critical gravity load that will cause longitudinal buckling failure, kips 
2
??
?
  critical gravity load that will cause transverse buckling failure, kips 
2
???????
  critical gravity concentrated load that will cause crushing failure, kips or tons 
2
?????????
  gravity load pile can carry without failure with included factory of safety, kips 
2
????????
  gravity load pile can carry in end-bearing without plunging failure, tons 
 
 xv
2
????????
  gravity load pile can carry in friction without plunging failure, tons 
.
??
  length of pile below ground before scour event (from OGL to pile tip), feet 
S scour value, feet 
5
??
  critical scour value that will cause failure, feet 
5
???
  section modulus at effective section location, in? 
SI&A Structural Inventory and Appraisal 
5
???
  maximum estimated scour value at bent or pile, feet 
ST screening tool 
VBA Visual Basic Code 
?
????????
  pile stress that will cause crushing failure, ksi 
? diameter of pile, inches 
 
 
 
 
 
 
 
 
 
 
 
1 
 
 
 
 
CHAPTER 1  
INTRODUCTION 
1.1 Problem Statement 
 For bridges over water, extreme flood events must be considered when 
assessing the safety of the structure.  Excessive scour at the ground line can produce a 
significant loss of embedment, leading to stability failure.  In addition, debris collected by 
the flood waters can accumulate on bents, producing a lateral force.  Timber pile bents 
are a common substructure utilized by counties for bridges over water.  These bridges 
are used on low-volume roads, but the quantity of them is much greater than that of 
highway bridges that generally use concrete or steel piles.  
 A screening tool for the evaluation of bridges subject to scour has been created 
by Auburn University for the Alabama Department of Transportation (ALDOT) for 
bridges that have steel piles.  By directive of the federal government, ALDOT is also 
tasked with the scour evaluation of county bridges.  Since this includes a large number 
of bridges, an automated screening tool for timber pile bents was thought to be 
exceptionally beneficial to ALDOT as they complete this obligation. 
1.2 Research Objective 
 The possible failure modes of timber pile bents were identified and the 
calculation of critical scour depths associated with those failure modes was 
accomplished.  Failure modes and investigative procedures used in the manual (non-
2 
 
automated) version of the screening tool were previously outlined in the Milestone No. 1 
report (Ramey et al. 2010).  The discussion is continued in this thesis to include a 
description of the automation of the screening tool.  While the manual tool is useful, a 
computer-automated tool is more beneficial for ALDOT.  With a computerized tool, they 
can screen timber bents more rapidly, and with a printable output report, documentation 
will be streamlined.  When an atypical bent is encountered, the manual tool procedures 
can be referenced in order to screen the bent. 
1.3 Work Plan 
The automation of the screening tool adhered to the following work plan: 
(1)  Familiarization with stability failure modes outlined in the manual screening 
tool, especially the manual screening tool flowcharts that provide a basis for 
code procedures; 
(2)  Familiarization with Visual Studio 2005 /2010 and Visual Basic code 
including tutorials outlined in Microsoft Visual Basic 2005: Step by Step 
(Halvorson 2006) to prepare for coding process; 
(3)  Familiarization with the  previous screening tool for steel piles to gain an 
understanding of the type of presentation expected by ALDOT and to 
pinpoint areas that could be updated for the tool to become more accessible; 
(4)  Coding of the timber screening tool using Visual Basic (VBA) code; 
(5)  Collaboration with ALDOT employees for feedback to better suit the tool for 
their needs; 
(6)  Development of a printable output report with assistance from personnel in 
the Engineering Network Services Department at Auburn University; 
3 
 
(7)  Preparation of a final report for ALDOT, in conjunction with a final seminar, to 
present the finished product. 
4 
 
?
?
?
 
 
CHAPTER 2  
LITERATURE REVIEW 
 
 Bridge scour is the erosion of bed material around bridge foundations due to 
water flow typically associated with granular stream or river beds (Maddison 2012).  A 
literature review focusing on the current research in bridge scour monitoring was 
conducted to develop a full understanding of the scour problem.  Because a federal 
mandate was the driving force behind this research, the applicable legislation related to 
all state highway departments? bridge monitoring programs was reviewed.  The 
mechanics of scour and current scour monitoring practices were considered.  The 
current analysis procedures of scour-affected bridges was reviewed, including those 
procedures previously employed by Auburn University personnel for the development of 
a steel stability screening tool.  A smaller literature review was also conducted focusing 
on the material properties of timber in order to distinguish reasonable material 
assumptions for use in the screening tool.  Finally, because the ultimate goal of the 
research was to produce a computer-automated screening tool, a review of Visual Basic 
code writing was necessary. 
2.1 National Bridge Inspection Standards 
 The inspection and upkeep of all bridges on public roads is mandated by the 
Federal Highway Administration (FHWA), with the responsibility falling on each state?s 
department of transportation to comply according to the Code of Federal Regulations, 
Title 23, Part 650 ?Bridges, Structures, and Hydraulics? (2004).  Bridge inspection, 
5 
 
specifically, is covered under Subpart C, National Bridge Inspection Standards (NBIS) 
of the Code.  According to the Code, ?each State transportation department must 
inspect, or cause to be inspected, all highway bridges located on public roads that are 
fully or partially located within the State?s boundaries?.  The Alabama Department of 
Transportation (ALDOT), as of April 2012, is in charge of 2,217 state and county 
bridges.  ALDOT must provide a bridge inspection section accountable for proper 
inspection of bridges, compilation of a comprehensive bridge inventory, and 
determination of up-to-date load rating of its bridges.  This team is comprised of 
hydraulic, geotechnical, and structural engineers (Hunt 2005). 
   Inspection of bridges is the section?s first priority.  According to FHWA, routine 
inspections of bridges should occur on minimum 24-month (2 year) intervals, while 
underwater inspections should occur on 60-month (5 year) intervals.  During inspection, 
problems such as ?scour critical? bridges should be identified.  After identification, a 
strategy must be formed to attend to the scour issues and to observe the bridge for 
further scour issues.  In addition, the safe load-rating of the bridge must be determined.  
While a bridge with severe scour problems may need to be closed, some affected 
bridges may remain open under a load restriction. 
 In addition to an inspection, an inventory of the State?s bridges must be produced 
and maintained.  The inventory should contain Structural Inventory and Appraisal 
(SI&A) data as defined by the ?Recording and Coding Guide for the Structure Inventory 
and Appraisal of the Nation?s Bridges? (1995).  Required data include logistical 
information such as location, geometrical information such as span and deck widths, 
load rating information, et cetera, in addition to the structural evaluation of the bridge.  
6 
 
Maintenance of such a database allows for successful bridge supervision and therefore 
public safety.  Many past bridge failures were preventable, but improper inspection and 
inadequate repairs led to a catastrophe (Maddison 2012).   
  ?Scour Critical Bridges? are designated as Item 113 of the SI&A guide.  If a 
bridge review produces a rating of 4 or less, the load-rating of the bridge must be 
reevaluated.  A summary of the critical road ratings can be seen in Table 2.1. 
Table 2.1 Critical Ratings for Item 113 of SI&A Guide:  
Scour Critical Bridges (FHWA 1995) 
Rating?? Description?
4?
Bridge?foundations?determined?to?be?stable?for?calculated?scour?conditions;?field?review?
indicates?action?is?required?to?protect?exposed?foundations?from?effects?of?additional?
erosion?and?corrosion.?
3?
Bridge?is?scour?critical;?bridge?foundations?determined?to?be?unstable?for?calculated?scour?
conditions:??scour?within?limit?of?footing?or?piles?or?scour?is?below?spread?footing?base?or?
pile?tips.?
2?
Bridge?is?scour?critical;?field?review?indicates?that?extensive?scour?has?occurred?at?bridge?
foundations.??Immediate?action?is?required?to?provide?scour?countermeasures.?
1?
Bridge?is?scour?critical;?field?review?indicates?that?failure?of?piers/abutments?in?imminent.??
Bridge?is?closed?to?traffic.?
0? Bridge?is?scour?critical;?bridge?has?failed?and?is?closed?to?traffic.?
 Due to the large volume of bridges under ALDOT jurisdiction, it was thought that 
a screening tool would greatly alleviate some of the difficulty in maintaining the NBIS 
bridge inventory.  The automated screening tool?s help would be twofold: to streamline 
the inspection process and to provide printable documentation for the bridge inventory. 
2.2 Scour Failure of Bridges 
 According to FHWA, of the 590,000 bridges in their inventory, 26,472 bridges are 
scour critical.  In addition, scour related problems are responsible for over 60% of bridge 
failures (Hunt 2005).  An average annual cost of bridge repairs related to scour damage 
7 
 
is $50 million (Bennett et al. 2009).  Due to this economic and safety hazard, scour and 
it effects are heavily-researched topics. 
 Scour can be categorized into three major types:  channel instability, contraction 
scour, and local scour (Maddison 2012).  Channel instability, or natural scour, is the 
normal amount of erosion all flowing water bodies experience.  However, because the 
amount of scour increases with increases in water flow, severe scour can occur during 
flooding or periods of extreme runoff.  A dramatic increase in flow, and consequently 
scour, can also occur due to dredging near the bridge site, formation of debris rafts, or 
collapse of other structures local to the bridge site.   
 Contraction scour occurs when the stream or river experiences a dramatic 
decrease in cross-section.  When the cross-section decreases, the flow velocity 
increases, thereby generating more scour.  Finally, local scour is attributed to the 
incidence of an obstruction, such as a pile, in the channel.  Because the water must flow 
around the pier, turbulence is created.  This turbulence uplifts the bed material 
upstream of the pile and deposits the material behind the pile as shown in Figure 2.1 
(Maddison 2012).   
8 
 
. 
Figure 2.1 Plan and Elevation View of Local Scour (Maddison 2012) 
 Maddison (2012) also outlines several United Kingdom bridge failures attributed 
to scour.  A fatal 1987 bridge collapse in Glanrhyd during heavy rainfall was attributed to 
local scour in addition to minor channel instability.  It was determined in the post-failure 
investigation that the engineers did not fully understand the flow of the channel, 
foundation depths were unknown, and previous repairs had actually increased scour 
(Maddison 2012).   
 In a separate case study, a railway bridge in Beighton partially collapsed in 2003 
due to contraction scour.  A very deep scour hole developed around the bridge pier, 
resulting in a much shallower foundation than was originally present.  The center pier 
collapsed into the hole, while the arch being supported by the pier partially fell in.  
Underwater inspections had been conducted by maintenance personnel, but no scour 
hole had been reported prior to collapse.  Also, it was noted that the scour most likely 
took place during winter flooding, but the failure was not reported until the summer 
(Maddison 2012).   
9 
 
 These oversights illustrate the necessity of a maintaining a comprehensive 
bridge monitoring program executed by trained personnel.  Maddison concludes that 
while extensive time and effort are put into forensic investigations after a bridge failure, 
?if that same effort could be put into bridge management regimes, collapses could be 
avoided.?  It was also noted that while extensive documentation on a structure exists, it 
is not often readily available to the engineers during the bridge design process or to the 
engineers conducting the underwater investigations.  The prevalence of computers, 
however, should ?now make it easy to rectify this problem? (Maddison 2012). 
2.3 Scour Monitoring Practices 
 Because of the safety risk associated with the failure of bridges, in addition to the 
federal mandate, countermeasures must be employed to manage or impede scour.  
Counter measures are typically either hydraulic, structural, or monitoring 
countermeasures (Hunt 2005).  Hydraulic measures may consist of redirecting flow, 
while structural measures incorporate amendments made to the bridge substructure.  
Scour monitoring, however, is more of a preventative measure than a countermeasure.  
Monitoring can be achieved by either instrumentation or by visual inspections (Hunt 
2005).   
 Because the repair, or entire replacement, of a scour critical bridge is expensive 
and requires substantial effort on the part of the state department, early detection is 
preferred (Hunt 2005).  Monitoring can occur after periods of high rainfall, flow, or flood 
events in addition to the required regularly-scheduled bridge inspection mandated by 
FHWA.   
10 
 
 This research is focused on visual monitoring of a scour susceptible bridge.  A 
visual inspection is required to provide basic bent geometry and scour conditions at a 
site before using the screening tool.  Visual inspection, however, is not the only avenue 
for scour countermeasure.  Therefore, a review of current scour monitoring measures 
was conducted.   
 In addition to visual monitoring, many departments have installed fixed 
instrumentation to monitor scour at bridge foundations (Hunt 2005).  The most obvious 
benefit of installing fixed monitors is the continuous observation of scour.  There are 
currently two types of fixed monitors:  sonic fathometer and magnetic sliding collar 
monitors.  Sonic fathometers, when attached to a pier, provide measurements at user-
defined intervals of the bed material depth, which are collected into a database.  From 
the database, the rise and fall of scour over time can be determined.  Magnetic sliding 
collars, when fitted to a pile, fall with the stream bed during scour.  Maximum scour 
depth, then, can be determined, but the changes in scour over time cannot be 
determined (Hunt 2005).   
 ?Float out? devices can be buried at critical depths in the stream bed.  When 
scour reaches this critical depth, the device is unearthed and then emits a warning 
(Hunt 2005).  Presently, 32 states utilize scour monitoring systems covering a total of 
120 bridge foundations, including pile foundations, spread footings, and drilled shafts 
(Yu and Zheng 2012). 
 Currently, new scour instrumentation is being developed.  Tilt sensors, which 
monitor the structural movements of the bridge rather than the scour depth, are a 
relatively new product.  McConnell and Cann (2011) reviewed the tilt sensor scour 
11 
 
monitoring system using a case study at the Indian River Inlet Bridge in Sussex County, 
Delaware.  Scour exposes more pile length, thereby generating movement of the bridge 
assembly that the attached tilt sensors detect.   
 Monitors using mobile wireless technology, in conjunction with ground-
penetrating radar (GPR), have also been researched in Seoul, South Korea.  The scour 
depth, in addition to a geophysical assessment of the filling of scour holes via the GPR, 
can be sent to an offsite monitor, conducting safety evaluations instantaneously (Yu and 
Zheng 2012). 
 Computer programs specifically designed for screening bridge failure 
susceptibility after scour events are also used as part of an effective scour monitoring 
program.  For example, a program for evaluating pile corrosion in marine environments 
has been developed (Zmeu 2012).  While corrosion is not a direct effect of scour, as 
compared to the increased exposed pile length, the high water associated with scour 
events is favorable for pile degradation issues.  Therefore, the effects of corrosion and 
marine borer presence are often included in scour investigations.  The engineer may 
input estimated section losses into the computer program, which then evaluates the pile 
for localized buckling at critical sections, and global buckling of the entire pile.  An 
output report is also produced by the program for documentation of the inspection 
(Zmeu 2012). 
 ALDOT presently uses an automated screening tool for the stability of steel 
bridge bents.  This comprehensive tool checks for kick-out, plunging, buckling, 
pushover, and beam-column failures of piles and bents subject to scour.  Because this 
steel tool has been well-received, the present research effort is concerned with the 
12 
 
development of a comparable automated timber screening tool for ALDOT?s scour 
monitoring program. 
2.4 Structural Analysis of Scour Critical Bridges 
 Much research related to scour deals with the hydraulic component, i.e., it is 
mainly focused on describing the scour mechanism.  Less research is concerned with 
the structural implications of scour (Bennett et al. 2009).  The main structural failure 
types related to scour are as follows:  pile plunging, pile buckling, pile corrosion, kick-out 
failure, and pushover failure (McConnell and Cann 2011).  A useful stability screening 
tool, then, should at least evaluate all of these failure modes.  The present timber 
screening tool, in addition to these failure modes, also includes a less-researched 
failure mode: upstream pile beam-column failure.  Past analysis procedures for typical 
failure modes were reviewed in order to determine the best approach for the 
development of the timber screening tool. 
2.4.1 Pushover Analysis of Scour Critical Bridges 
 To establish the maximum tolerable displacement for tilt sensors at the Indian 
River Inlet Bridge (McConnell and Cann 2011), a finite element model was created to 
perform pushover analyses.  Using Capacity Analysis Pushover Program (CAPP), a 
one-dimensional model of a single bent was created and then was laterally loaded in 
the direction of water flow.  The lateral load was a combination of hydrostatic pressure 
due to water flow at the pier and wind acting on the bridge face, represented by a line 
load along the submerged pile portions.  This load was much less than the load required 
to yield the concrete reinforcement, therefore it was expected that all piles would remain 
elastic. 
13 
 
 Because bridge bents may act separately, it was assumed that modeling a single 
bent instead of an entire bridge would be sufficient.  The concrete piles were modeled 
using beam elements connected by a rigid link serving as the pile cap.  A pile batter 
could not be directly input into the finite element software so an increase in the pile 
moment of inertia was used to account for the increased stiffness due to pile batter.  
The soil profile at the Indian River Inlet Bridge consisted of a layer of clay overlaying a 
dense layer of sand.  Soil properties needed for the program were estimated using like 
soil profiles rather than by direct soil testing.  Soils were conservatively assumed to 
have no post-yield plastic behavior (McConnell and Cann 2011). 
 According to the current AASHTO limit states for bridges, the maximum tolerable 
displacement for strength is 13 mm (0.53 in.), while the maximum tolerable 
displacement for serviceability is 6 mm (0.23 in.) (McConnell and Cann 2011).  The tilt 
sensors, then, would be installed such that displacement past this criterion would alert 
the engineers to potential failure.  The sensors, however, can only indicate pushover 
failure, while neglecting the other major failure modes.  In addition, the authors noted 
that, based on the finite element models, bents displacing more than 6 mm (0.23 in.) 
were, in fact, behaving inelastically (McConnell and Cann 2011).  Therefore, for a 
quality pushover analysis, it was concluded that post-yield behavior of piles should be 
included. 
 Another bent pushover analysis was completed for Kansas Bridge 45 utilizing the 
Group Equivalent Pile (GEP) method (Bennett et al. 2009).  Nonlinear behavior of both 
the piles and soil were included in the analysis.  The soil profile was modeled using 
nonlinear springs at the base of the piles.  Instead of modeling the entire pile group, an 
14 
 
?equivalent? pile which represented the entire group?s behavior was used.  This was 
accomplished by using a pile with an unchanged cross-sectional area, but with an 
increased moment of inertia equal to the sum of the entire pile group.  This pile was 
then loaded with a fraction of the lateral load on the entire pile group.  The behavior of 
the entire pile group was then extrapolated from the single equivalent pile pushover 
analysis using a constant referred to as a ?p-multiplier? (Bennett et al. 2009). 
2.4.2 Computer Modeling Approaches for Scour Critical Bridges 
 It has been proposed that a specific computer model for a scour critical bridge is 
an effective and accurate monitoring approach.  Yu and Zheng propose a model that 
can be continuously updated based on on-site sensor measurements of scour (2012).  
For the case study, SAP2000 (a commonly-used structural modeling software) was 
used to create a model of the No. 127.9 Bridge located on U.S. Highway 61.  Pile bents 
were represented by a single pile connected by frame elements.  The soil was 
represented by springs, analogous to a beam on a Winkler foundation, where the 
removal of springs imitated scour (Yu and Zheng 2012).   
 Lin et al. took a different approach to the modeling:  combining structural and 
foundation analysis software to produce an integrated bridge model (2012).  Playing to 
each software?s strength, FB-MultiPier was used to complete a nonlinear substructure 
analysis while STAAD Pro was used to complete a nonlinear superstructure analysis.   
The FB-MultiPier results were converted to a stiffness matrix that could describe spring 
supports for the STAAD Pro model.  Loads were then applied to the integrated STAAD 
Pro bridge model, producing pile cap loads which could be integrated back into the FB-
MultiPier model.  After iteration, the two models reached equilibrium.  To demonstrate 
15 
 
the modeling approach for scour critical bridges, the Kansas Bridge 45 was modeled 
using the integrated method, then buckling capacities and lateral responses after scour 
were determined (Lin et al. 2012). 
 While both Yu and Zheng and Lin et al. methods are accurate for the modeling of 
scour critical bridges, the methods are both time- and labor-consuming.  Lin et al. 
especially made an effort to use software familiar to bridge design engineers so that the 
method could have practical applications.  This method could be very beneficial for 
high-profile or vital scour critical bridges, however, due to the large number of bridges 
under ALDOT supervision requiring monitoring, computer models completed on a per-
bridge basis is not a feasible state-wide scour monitoring practice.  A screening tool, 
covering a wide range of bridges, is more valuable to ALDOT. 
2.4.3 Steel Screening Tool 
 In order to develop a comparable timber stability screening tool, the previous 
steel screening tool analyses were used as a framework.  While pushover analyses 
separate from the steel tool were necessary due to considerable differences in 
geometry and material properties, the equations for kick-out, plunging, buckling, and 
beam-column needed only to be tailored to the new tool.  Discussion of the specific 
equations, and their tailoring, is presented in Chapter 4. 
2.5 Material Properties of Timber Piles 
 The previous screening tool was concerned with bridges constructed using steel 
pile bents.  Therefore, to develop the present tool, it was necessary to conduct 
investigations of timber as a construction material.  Timber piles, in addition to having 
different material properties, have inherent geometric differences from steel piles, most 
16 
 
notably the timber pile taper.  Adjustments were made to the previous screening tool 
analyses to account for these differences. 
 A schematic drawing of a typical timber pile is shown in Figure 2.2.  Note the 
significant pile taper, or change in diameter, that is characteristic of timber piles.  Timber 
piles must be tapered in order to drive them into soil.  For the pile shown, the taper 
corresponds to a 1.17 inch decrease in diameter per 10 feet of pile.  The pile is from a 
set of timber utility poles investigated by P.S. Quintero (1980) in a region of 
Birmingham, Alabama hit by a severe tornado in 1977.  Note the designation that the 
butt diameter value is typically taken as the diameter 3 feet from the top of the pile. 
 
Figure 2.2 Typical Timber Pile (Quintero 1980) 
17 
 
 Typical limiting dimensions of common timber piles are summarized below in 
Table 2.2, adapted from R.D. Chellis (1961). 
Table 2.2 Typical Limiting Dimensions of Piles, Inches (Chellis 1961) 
Place?
measured?
Timber?Species?
Southern?pine?and?Douglas?fir?
Oak,?cypress,?and?
chestnut?
Cedar?
<?40?ft?
long?
40?50??
ft?long?
51?70?
?ft?long?
71?90?
ft?long
>?90?ft?
long?
<?30?ft?
long?
30?60?
ft?long
>?60?ft?
long?
<?30?ft?
long?
30?60
?ft?long
>?60?ft?
long?
ASTM,?ASA,?and?CESA?Class?A?piles?for?railway?bridges?
Butt*?
(min.)?
14? 14? 14? 14? 14? 14? 14? 14? 14? 14? 14?
Butt*?
(max.)?
18? 18? 18? 20? 20? 18? 18? 18? 22? 22? 22?
Tip?(min.)? 10? 9? 8? 7? 6? 10? 9? 8? 10? 9? 8?
ASTM, ASA, and CESA Class B piles for highway bridges?
Butt* 
(min.) 
12 12 13 13 13 12 13 13 12 13 13 
Butt* 
(max.) 
20 20 20 20 20 18 20 20 22 22 22 
Tip (min.) 8 7 7 6 5 8 8 7 8 8 7 
ASTM, ASA, and CESA Class C piles for second-class construction 
Butt* 
(min.) 
12 12 12 12 12 12 12 12 12 12 12 
Butt* 
(max.) 
20 20 20 20 20 20 20 20 22 22 22 
Tip (min.) 8 6 6 6 5 8 8 6 8 8 7 
*?Butt?dimensions?taken?8?ft?from?end. 
 It should be noted that alternate wetting and drying of piles that occurs near the 
water line for timber piles supporting bridges over water subject the piles to wood rot, 
fungus growth, and marine animal or insect attack.  The severity of the wood decay due 
18 
 
to these factors can be greatly reduced by chemical treatment of the wood piles, but 
such treatment will not entirely prevent decay.  This is especially critical in situations 
where the pile is exposed to the air and alternately to wet and dry periods, as is typical 
for timber bridges over water (Ramey et al. 2011).  Rot or insect attack will result in the 
loss of cross section, therefore the loss of section modulus, which is required for 
bending capacity.   
 The approximate modulus of elasticity (E), crushing strength, and bending 
strengths of timber piles most commonly used in Alabama are shown in Table 2.3.  The 
values are extracted from Chellis (1961). 
Table 2.3 Approximate Elastic Modulus and Strengths of Woods Commonly Used 
for Timber Piles in Alabama (Chellis 1961) 
Wood 
Species 
Green (Untreated) Air-Seasoned (Untreated) 
Elastic 
Modulus, E 
(psi) 
Crushing 
Strength 
(psi) 
Bending 
Strength 
(psi) 
Elastic 
Modulus, E 
(psi) 
Crushing 
Strength 
(psi) 
Bending 
Strength 
(psi) 
Pine-
Longleaf 
1,600,000 4,300 8,700 1,990,000 8,440 14,700 
Pine ? 
Shortleaf 
1,390,000 3,430 7,300 1,760,000 7,070 12,800 
Douglas 
Fir 
1,550,000 3,890 7,600 1,920,000 7,420 11,700 
Southern 
Cypress 
1,180,000 3,580 6,600 1,440,000 6,360 10,600 
Oak - 
White 
1,200,000 3,520 8,100 1,620,000 7,040 13,900 
 In timber design, nominal strength capacities, such as those shown in Table 2.3, 
are adjusted for the effect of load, environment, and construction.  Shaeffer (1980) 
states that when the duration of loading is known, the allowable stresses for timber may 
be increased by the following factors: 
 
19 
 
Table 2.4 Load Duration Modification Factors for Timber (Schaeffer 1980) 
Load Duration Modification Factor
Two Months (Snow) 1.15 
Seven Days 1.25 
Wind or Earthquake 1.33 
Impact 2.00 
 Based on these values, it was assumed for extreme scour that an allowable 
stress modification factor of 1.30 is appropriate.  Shaeffer states that the modulus of 
elasticity values are not subject to such modifications.  Based on common timber 
species and with application of the load duration modification factor, the following 
material properties were used in the screening tool: 
Table 2.5 Timber Pile Material Properties Used in Screening Tool 
Material Property Value used in ST
Young's Modulus, E (ksi) 1,800 
Crushing Strength (ksi) 7.00 
Bending Strength (ksi) 12.0 
In order to determine buckling length, the end conditions of the pile must be 
estimated.  To help gain a sense of depth of pile embedment required to achieve a 
?fixed? end condition for checking bent pile buckling after a major scour event, timber 
utility pole embedment specifications of the Alabama Power Company were examined.  
Table 2.6 shows some select geometrical properties of ground-embedded timber utility 
poles.  This table was adapted from select circa-1980 tables of the Alabama Power 
Company Specifications and Standards (Quintero 1980).  Note that the length of pile 
above ground is designated as .
??
 and the embedment length below ground as .
??
.  
The symbol ?D? designates the diameter and ?S? the section modulus. 
20 
 
Table 2.6 Geometric Properties of Select Timber Utility Poles* (Quintero 1980) 
Pole 
Pile 
Length,   
L (ft) 
Pile 
Embedment, 
L
bg
 (ft) 
L
ag
/L 
Pile 
Height, 
L
ag
 (ft) 
D
base 
(in) 
D
top 
(in) 
D
avg 
(in) 
S
base 
(in
3
) 
30/7 
30 5.5 0.183 24.5 
7.54 4.78 6.16 42 
30/6 8.01 5.41 6.71 50 
30/5 8.81 6.05 7.43 67 
35/6 
35 6.0 0.171 29.0 
8.59 5.41 7.00 62 
35/5 9.23 6.05 7.64 77 
35/4 10.0 6.68 8.36 99 
40/6 
40 6.0 0.150 34.0 
9.07 5.41 7.24 73 
40/5 9.87 6.05 7.96 94 
40/4 10.7 6.68 8.67 119 
45/6 
45 6.5 0.144 38.5 
9.50 5.41 7.46 84 
45/4 11.1 6.68 8.88 134 
45/2 12.8 7.96 10.4 207 
50/4 
50 7.0 0.140 43.0 
11.5 6.68 9.10 150 
50/3 12.3 7.32 9.81 183 
     *From Alabama Power Company Distribution Standard Drawing A-194823 
Note that the diameter, and therefore section modulus, is the largest at the base 
for timber utility poles since they are embedded with the diameter increasing from top to 
bottom.  Timber bridge piles, however, are embedded with a decreasing taper.  For 
piles, the larger diameter is at the cap because high axial loads and smaller lateral 
loads are typical for bridge design.  However, the depth of embedment of utility poles 
gives an approximation of percentage embedment required to develop a reasonable 
moment resistant fixity at the ground line.  This is important because for an unbraced 
bent, piles require a significant fixity at the ground for stability. 
During the development of the previous steel stability screening tool, soil-pile 
interaction was also considered.  According to Hughes et al. (2007), the soil subgrade 
modulus does not have any real effect on the deflection of steel piles.  Pile ?fixity? was 
determined to occur at 1.5 meters (or 5 feet) of pile embedment (Hughes et al. 2007). 
21 
 
2.6 Review of Visual Studio and Visual Basic Code Writing (VBA) 
 While the author already had some experience in Visual Basic (VBA) code 
writing, more education was required for the development of the automated timber 
screening tool.  A Visual Studio 2005 guide by Halvorson (2006), including example 
problems and techniques, was consulted in addition to the previous steel stability 
screening tool.  Its code was often used as a learning tool or as a base template for the 
timber screening tool. 
  
 
 
 
22 
 
 
 
 
CHAPTER 3   
SCOUR MONITORING OF COUNTY BRIDGES  
SUPPORTED ON TIMBER PILE BENTS 
3.1 General 
 The need for an automated screening tool to evaluate the stability of bridges 
subject to scour was established in Chapter 2.  While a steel stability screening tool has 
been produced by Auburn University personnel and is currently in use by ALDOT 
personnel, the bridge inventory does not consist solely of steel-pile-supported bridges.  
In the past, two-lane highway timber-bent-supported bridges were commonly used by 
counties, as well as by some state departments of transportation, in the United States.  
A typical timber pile bent in Alabama is shown in Figure 3.1.  Note the cross-bracing 
that is typical for timber bents. 
 
Figure 3.1 Typical Timber Pile Bents (provided by ALDOT)  
23 
 
Some of these bridges are still in existence, in addition to bridges that have had their 
timber superstructure replaced with combinations of steel or concrete girders with a 
concrete deck, while continuing to use the original timber pile bent substructure.   
 The volume of timber-pile-supported bridges under ALDOT jurisdiction is 
extensive.  Therefore an automated timber screening tool comparable to its current 
steel screening tool was requested by ALDOT personnel.  The tool was envisioned as 
using visual inspection data to perform structural stability analyses.  These analyses 
should indicate whether the bridge is scour critical.  In addition, the scour value at which 
failure becomes imminent, also called the critical scour depth, should also be 
determined by the tool.  A printable report was also requested for documentation in the 
National Bridge Inventory System (NBIS). 
 It is important to stress that the tool is meant only ?screen? to scour susceptible 
bents and therefore generic assumptions must be made to cover a wide range of timber 
bridges.  All geometric and material assumptions made by the screening tool are 
identified in this chapter.  In order to effectively use the tool, an understanding of these 
assumptions is required.  ALDOT performed a survey of timber structures to provide a 
realistic range of bent configurations for the purpose of creating a generic stability 
screening tool.  The parameters needed for assessment and the resulting values are 
discussed in this chapter.  In addition, the timber material property assumptions made in 
the development of the screening tool are outlined.  The computation of the debris raft 
forces assumed by the screening tool is also discussed.   
 
 
24 
 
3.2 Bridge Parameter Values Needed to Assess Bridge Stability 
 In order to assess the adequacy of a bridge during a major flood or scour event, 
bridge engineers must know vital information pertaining to the bridge superstructure and 
live loads acting thereon, such as support pile bent geometry and member sizes; pile 
driving and support soil conditions; river or stream high water level, flow velocity, level of 
possible scour.  The most basic information needed is presented graphically in Figure 
3.2.  The parameters include the following: the bent height, H; the lateral force acting on 
the bent, null
null
; the location of the high water line, HWL; the gravity loads, P; the diameter 
of the piles, ?; the number of piles; the bracing configuration; the elevation of the 
original ground line, OGL; and the maximum depth of scour, S.  
 
Figure 3.2 Transverse Section of a Typical Timber Bridge with 
Information Needed to Assess Adequacy During an Extreme Scour Event 
3.3 Possible Failure Modes of Timber Pile Bents 
 Based on past experience in screening ALDOT bridges as indicated in the Phase 
I through III Reports (Ramey et al. 2004; 2006; 2008), possible failure modes of bridge 
pile bents during extreme scour events are as follows: 
 (1)  Kick-out of the pile bent due to zero or negligible embedment after scour; 
25 
 
 (2)  Plunging due to soil failure; 
 (3)  Buckling failure in either the longitudinal or transverse direction; 
(4)  Bent pushover failure due to the combined superstructure gravity and lateral 
debris raft loadings; 
(5)  Beam-column failure of the upstream pile due to the combined lateral debris 
raft and axial gravity loadings. 
It should be noted that crushing of a pile during an extreme scour event is not a viable 
failure mode for timber piles.  Recalling that 7.0 ksi is assumed to be the crushing stress 
for a timber pile, even for the smallest considered diameter (6 inches) the minimum 
crushing load, as determined in the following equation, is 198 kips, which is much 
greater than the maximum pile applied load considered in the screening tool of 60 kips.  
null
nullnullnullnullnullnullnullnull
nullnull
nullnullnullnullnullnullnull
?nullnullnullnull null 7.0 nullnullnull null
null6
null
4
null null 198
null
null null
nullnullnullnullnullnullnullnullnullnull
null60
null
 
In addition, null
nullnullnullnullnullnullnullnullnullnull
 and null
nullnullnullnullnullnullnullnull
 of the piles are unaffected by a scour event, 
therefore crushing will not be affected by an extreme scour event. 
 Buckling, plunging, bent pushover, kick-out, and beam-column failures are the 
only realistic catastrophic failure modes, and therefore are the only five modes of failure 
that require consideration.  Each of these possible failure modes and the manner for 
checking each of them is discussed in detail in the following chapter. 
3.4 Typical Value Ranges of Alabama County Bridges 
 After completing a survey of timber bridges, ALDOT personnel determined that 
the following typical values and ranges of values were appropriate for the screening 
tool.  First, hydrologic data indicated scour depths of 5, 10, 15, and 20 feet are 
expected.  The average estimated high water line is 10 feet from the ground line.  A 
26 
 
review of typical bent geometries yielded bent height ranges from 6 to 22 feet with an 
average of a 10 foot bent height.  Therefore, bent heights of 8, 12, 16, and 20 feet were 
considered in the screening tool.  The number of piles per bent was found to be 3, 4, or 
5, with 4 piles per bent being the most common configuration.  Piles are spaced at 
distances ranging from 5.3 feet to 7.8 feet, therefore an average value of 6.5 feet was 
assumed for this effort.  Piles, if battered, use a 1:12 batter.  Both one-story and two-
story bracing was observed for timber pile bents; however, this screening tool only 
considers one-story bracing.  Note that because two-story bracing is stiffer than one-
story bracing, this limitation is conservative.  
Pile driving data was also investigated.  Pile lengths varied from 15 to 40 feet 
with an average of 31 feet.  Pile tip diameters were 7, 9, and 10 inches, while pile butt 
diameters were 12, 13, and 14 inches.  The screening tool considers 12 and 14 inch 
diameter butts.  Probable final driving resistances ranged from 2.5 to 8 blows per inch 
(bpi) with 4 bpi being the average.  Most piles were driven using a drop hammer with 
10,000 to 15,000 ft-lb of driving energy.  Embedment varied from 9 to 32 feet with an 
average of 22 feet. 
It is also necessary that superstructure characteristics be known to determine 
loading and end conditions.  Bridge spans lengths ranged from 15 to 26 feet.  Bridge 
caps were either timber caps ranging from 10 in. by 10 in. to 12 in. by 14 in., or concrete 
caps ranging from 12 in. by 16 in. to 24 in. by 24 in.  Pile loads were determined to vary 
substantially, but all were assumed less than 60 kips.  Roadways were considered one-
way for all widths less than 18 feet.  Figure 3.3 summarizes the value ranges 
considered, along with the geometric assumptions used in the screening tool. 
27 
 
 
 
Figure 3.3 Alabama County Timber Pile Bent  
Ranges of Critical Assessment Parameters?
 
3.5 Material Assumptions Used in Screening Tool 
 As discussed in the literature review, material assumptions were needed for the 
screening tool.  To review: based on common timber species and with application of the 
load duration modification factor, the material properties summarized in Table 3.1 were 
used in the screening tool. 
28 
 
Table 3.1 Timber Pile Material Properties Used in Screening Tool 
Material Property Value used in ST
Young's Modulus, E (ksi) 1,800 
Crushing Strength (ksi) 7.00 
Bending Strength (ksi) 12.0 
 Due to pile taper, an effective section must be used to determine section 
properties of a particular pile.  For the screening tool, the section corresponding to two-
thirds of the pile height after scour measured from the top of the pile was deemed the 
appropriate effective section as shown in Figure 3.4 below.  In this figure, the length of 
scour is designated as S, the length of embedment below ground after the scour event 
is null
nullnull
, and the length of pile above ground after the scour event is null
nullnull
. 
 
Figure 3.4 Effective Section of Embedded Timber Pile (Ramey et al. 2011) 
29 
 
 The moment of inertia for a circular pile was determined as follows: 
null
nullnullnull
null
nullnull
nullnullnull
null
nullnull
 ,     (3-1) 
where null
nullnullnull
 is the diameter of the pile corresponding to two-thirds of the pile height 
measured from the pile cap after scour.  The effective section modulus for bending was 
determined to be the following: 
null
nullnullnull
null
nullnull
nullnullnull
null
nullnull
      (3-2) 
A plot illustrating the exponential increase in effective moment of inertia for 
timber piles with an increase in the pile effective diameter is shown in Figure 3.5.  Note 
that the timber pile buckling load consequently exhibits this same dramatic increase with 
increasing pile effective diameter. 
 
Figure 3.5 Variation of Pile Effective Moment of Inertia versus Pile Diameter
 
0
200
400
600
800
1000
1200
5 6 7 8 9 10111213
Effective
?
Moment
?
of
?
Iner
tia
?
(in
?
)
Effective?Diameter?(in)
30 
 
 For example, for a 50 foot pile with a diameter taper of 1.2 inches per 10 feet, the 
following effective section properties shown in Table 3.2 would be used by the 
screening tool: 
Table 3.2 Typical Effective Section Properties for Common Pile Sizes 
d
butt 
(in) d
tip 
(in) d
eff
 (in) I
eff
 (in
4
)E (ksi)EI
eff
 (k-in
2
) 
12 6 8.8 294 1,800 529,200 
14 8 10.8 668 1,800 1,202,000 
Notice that the effective moment of inertia for the 14 inch pile diameter is more than 
twice that of the 12 inch pile.  A pile taper is 0.12 inches per foot is assumed in the 
screening tool. 
3.6 Debris Raft Consideration for Small Span Bridges 
 In addition to conducting background research of timber as a construction 
material for bridge piles, it was necessary to reevaluate the debris raft calculation 
included in the previous screening tool for smaller span bridges.  In the previous steel 
screening tool, a single design raft force of 12.15 kips was used (Donnee et al. 2008).  
This lateral force corresponds to the size of debris raft that could accumulate on a 
bridge bent during flood events.  Steel bridges, however, are typically longer-span 
bridges as compared to low-volume timber county bridges. 
 The same process used to calculate the design lateral debris raft force in the 
steel screening tool was followed to calculate the timber screening tool design lateral 
forces.  Figure 3.6 illustrates this calculation.  Note that two raft forces, one 
corresponding to shorter bridge spans (less than 25 feet) and one corresponding to 
longer spans (25 to 36 feet) were employed by the screening tool.  The inclusion of the 
smaller raft force for shorter spans makes the screening tool more realistic for smaller 
31 
 
span bridges.  Without it, these small span bridges would be evaluated using an overly 
conservative debris raft force.  The raft force values are 6.48 and 9.72 kips for the small 
and large rafts, respectively.  After applying a factor of safety of 1.33, these forces are 
amplified to 8.62 and 12.93 kips.
?
V
design
 = 6 mph = 8.80 fps
A
DR
 = 
1
2
(A x B)
F
t
 = ?
water
 x A
DR
    = C
D
?
2g
? V
2
?  x A
DR
? 1.4 1? V
2
?  x A
DR
= 1.4 8.80()
2
?  x A
DR
F
t
 = 108 psf x A
DR
Bridge Span Lengths: 15 ft  ? L ?  36 null 
If 15 ft ???L??<?25?null?use?B?=?20?null?and?A?=?6?null? ??A
DR
?=?60?ft
2
If 25 ft ???L????36?null?use?B?=?30?null?and?A?=?6?null? ??A
DR
?=?90?ft
2
Therefore,
F
t
smaller
  = 108 psf x 60 ft
2
 = 6,480 lbs  = 6.48 kips
F
t
larger
    = 10 8psf x 90 ft
2
 = 9,720 lbs  = 9.72 kips
Using a FS = 1.33 
F
t
smaller
?
?
?
?
Design
  = FS x F
t
 =1.33 x 6.48 kips =  8.62 kips
F
t
larger
?
?
?
?
Design
    = FS x F
t
 =1.33 x 9.72 kips = 12.93 kips
Application of Pushover Force through Centroid of Debris Raft:
F
t
1
 acting as shown above for bent pushover analysis, while
F
t
2
 acting as shown above is used in check of upstream pile as a beam column
Figure 3.6  Debris Raft Force Calculation for Small Span Bridges
32
33 
 
 
 
 
CHAPTER 4   
FAILURE MODES FOR TIMBER BENTS SUBJECT TO SCOUR 
4.1 General 
 As indicated in Chapter 3, the five failure modes considered for timber pile bents 
during an extreme scour event are as follows: 
 (1)  Kick-out of the pile bent due to zero or negligible embedment after scour; 
 (2)  Plunging due to soil failure; 
 (3)  Buckling failure in either the longitudinal or transverse direction; 
(4)  Bent pushover failure due to the combined superstructure gravity loading and 
lateral debris raft load; 
(5)  Beam-column failure of the upstream pile due to the combined lateral debris 
raft load and axial gravity loading. 
The theoretical analysis procedures for each of these failure modes are outlined in this 
chapter. 
4.2 Kick-out Failure 
 Lateral forces created by water flow and debris rafts, shown as null
null
 in Figure 4.1, 
induce a lateral force at the tip of the pile, shown as null
nullnullnull
.  ?Kick-out? failure will occur if 
the passive earth pressures of the soil at the tip cannot overcome the force induced at 
the tip (Ramey et al. 2006).   
34 
 
.  
Figure 4.1 Pile Tip Kick-Out Failure  
 Because the passive earth pressure resistance is provided by the pile 
embedment, excessive scour will reduce kick-out capacity.  In the preceding steel 
screening tool, it was determined that for a remaining embedment of less than 3 feet, 
kick-out was possible (Donnee et al. 2008).  This minimum value included a factor of 
safety of 1.50.  However, this assumption cannot necessarily be made for timber piles 
due to differences in drag coefficients.  The drag force on a pile is proportional to the 
pile drag coefficient; a larger coefficient corresponds to a larger drag force that may 
develop to kick-out the pile.  For a steel pile, a drag coefficient of 2.0 was used, 
whereas for a timber pile, a drag coefficient of 1.2 is more correct.  Therefore, a timber 
pile would develop 40 percent less drag force. 
Because of the differences in drag coefficients, it was assumed that for 40 
percent less drag force, 40 percent less minimum embedment would be required for a 
35 
 
timber pile to prevent kick-out.  Therefore, the minimum length after scour required for 
the timber screening tool can be computed as 
    ?
nullnull
nullnullnullnullnullnullnull
null 3.0 nullnull null0.6 null 1.8 nullnull. 
Since embedment lengths of piles will be estimated, the minimum embedment length 
should be rounded up to 2.5 feet to account for error.  Accordingly, 
     ?
nullnull
nullnullnullnullnullnullnullnullnull nullnullnullnullnullnullnull
null2.5 nullnull. 
For an embedment less than 2.5 feet, kick-out failure is imminent.  Corrective action 
such as the placement of riprap around pile bases should be taken immediately. 
In order to ensure continual protection against kick-out during subsequent flood 
events, it is recommended that preventative measures be taken for any embedment 
length less than 5 feet, i.e. 
?
nullnull
 null  5.0 nullnull null nullnullnullnull nullnullnullnullnullnullnullnullnullnullnullnull nullnullnullnullnullnull nullnullnullnullnullnullnull nullnullnullnull nullnullnullnull 
4.3 Pile Plunging by Soil Failure 
 Excessive scour can alter a pile?s soil profile and can result in failure by plunging.  
Plunging failure occurs when pile bearing and side friction capacity do not provide 
enough resistance to support axial loads and the pile ?plunges? into the soil.  The axial 
resistance of a pile as provided by side friction and end bearing is illustrated in Figure 
4.2.  The magnitudes of these load-resisting forces are functions of both geometry and 
surface characteristics of the pile, as well as soil properties. 
36 
 
 
Figure 4.2 Pile Axial Resistance 
 It should be noted that the ability of the soil to support the load transmitted by the 
pile generally determines the adequacy of pile foundations, rather than the stresses on 
the pile itself.  The permissible working stresses for piles of any material are seldom 
fully utilized in a bent.  For example, if the maximum load null
nullnullnull
null60
null
 is applied to a 
timber pile and the minimum pile tip diameter is 6 in., the maximum stress is 2.12 ksi, 
determined as follows: 
null
nullnullnullnullnull
nullnullnullnull
null
60
null
null?6
null
4
null
60
null
28.3 nullnull
null
null 2.12 nullnullnull 
Even if the full P-load is carried down to the pile tip, disregarding soil properties, the pile 
would be considered safe because its maximum stress is quite low. 
 It should also be noted that because of their taper, timber piles develop 
significant wedge action and reactive side pressures from the soil and thus induce large 
skin friction resistance forces.  Relative to steel piles, timber piles act more like friction 
piles, as illustrated in Figure 4.3.   
37 
 
  
Figure 4.3 Elevation Schematics of Timber and Steel Wide-Flange Piles 
 The major variables affecting the axial resistance of a timber pile after scour are 
as follows: 
(1)  The driving resistance at the end of pile driving;  
(2)  The energy of the hammer used to drive the pile; 
(3)  The soil profile surrounding the pile; 
(4)  The amount and nature of scour that has occurred. 
Information on soil properties at each specific bent is typically inadequate or 
incomplete.  However, the driving resistance (blows per foot of penetration during pile 
driving) of the pile at the time of construction provides a crude, but reasonably reliable 
indication of soil resistance that has been mobilized.  Common required final driving 
resistance ranges are shown in Table 4.1 (Bowles 1968).  Often, piles may be driven to 
a commonly accepted final resistance without detailed recording of the blow counts.  In 
such a case, a conservative, or low, estimated final driving resistance is recommended 
for use in the screening tool. 
38 
 
Table 4.1 Common Required Final Driving Resistance Ranges (Bowles 1968) 
Pile Material
Final Driving Resistance 
(blows per inch) 
Timber 4-5 
Concrete 6-8 
Steel 12-15 
The energy of the hammer, in kip-feet, is expressed by the rated energy, which is 
equal to the weight of the ram (kips) multiplied by the height of the drop (feet); the 
values are often taken from a driving log.  For the screening tool, the driving system 
used for installing the pile must be known or estimated.  The rated energy must then be 
reduced to account for losses due to inefficiency, such as inherent friction losses, in the 
driving system.  Piles for small bridges in Alabama have typically been driven by one of 
several types of hammers with estimated efficiencies that are summarized below in 
Table 4.2. 
Table 4.2 Estimated Hammer Efficiencies 
Hammer Type Estimated Efficiency 
Single Acting Air/Steam 67% 
Double Acting Air/Steam 50% 
Diesel 80% 
Drop Hammer 50% 
 
Note that drop hammers can vary widely and are not currently used on ALDOT 
projects.  However, these have been used on many older bridges.   Note that with very 
high drop heights (more than 5 feet) and low ram weights, the energy losses for a drop 
hammer can result in an efficiency significantly lower than 50%.  
The soil profile can be used to determine whether piles are acting primarily as 
friction or end-bearing piles.  Dense sand strata, hard clays or marl, or rock underlying 
39 
 
soft alluvial soil are likely to represent a case where end bearing is the dominant mode 
of resistance.  Similarly, pile driving records that show relatively low blow counts 
followed by a dramatic increase in the driving resistance at some depth just prior to the 
end of driving would suggest a strong bearing layer.  Friction piles would likely be used 
where there are deep clay strata with no hard bearing layer; in such cases the pile 
embedded lengths would likely be great.  
Reduction in capacity is also related to the nature of the scour event.  Local 
scour, which is confined to a small area around the pile, will reduce the amount of soil in 
contact with the sides of the pile and will thereby reduce the side friction.  However, 
local scour does not have a major effect on the magnitude of the confining pressures on 
the soil at the tip and therefore does not significantly reduce the end-bearing capacity.  
General scour of the entire streambed around the bent would likely reduce the confining 
pressures in the ground at the pile tip and could therefore reduce the end bearing 
resistance as well as the side-shearing resistance.    
Correlations of pile driving resistance to axial static pile capacity have been 
developed using a number of simple pile driving formulas.  The current AASHTO 
specifications (2007) recognize and allow the use of the Modified Gates formula when 
insufficient information is available to create a wave equation model.  For timber 
bridges, which are often older structures without ample reliable data, the Modified Gates 
formula is well suited.  The equation, shown as Equation 4-1, correlates pile capacity 
with hammer driving energy and driving resistance at the end of driving (EOD) for a 
given pile hammer energy.   
 null
nullnullnullnullnullnullnull
null 0.875 null
null.null
 nullnullnull null10null
null
nullnull 50    (4-1) 
40 
 
null is defined as the nominal resistance in tons, null the energy produced by the hammer 
per blow in foot-pounds, and null
null
 the blow count in blows per inch.  Applying a factor of 
safety of 1.25 for plunging, the allowable resistance is 
null
nullnullnullnullnullnullnullnullnull
null
null
nullnullnullnullnullnullnull
null.nullnull
      (4-2) 
For the screening tool, the axial resistance prior to scour is assumed to be 
represented by one of two cases: (a) predominantly end-bearing action in which 75% of 
the axial resistance of the pile would be provided by end bearing and 25% by side shear 
or (b) predominantly friction resistance in which 25% of the axial resistance is provided 
by end bearing and 75% by side shear.  The latter case is more susceptible to scour 
since removal of the soil has a greater effect on side shear than on end bearing, as 
previously discussed.   
The proportion side shearing resistance lost is assumed to be proportional to the 
percent loss of embedment after scour. In a homogenous soil profile with general scour 
of the streambed (as opposed to localized scour) it is conceivable that the reduction in 
side-shearing resistance could be greater than the proportional percentage loss of 
embedment, due to the reduction in confining stress associated with scour.  However, it 
is anticipated that a significant proportion of the scour loss will usually be due to 
localized scour, which will not have a significant effect on confining pressure.  It is also 
expected that, more commonly, side-shearing resistance actually increases with 
increasing depth, and therefore a linearly proportional reduction in side shear is 
conservative.  In equation form, the percent loss of pile capacity in friction can be written 
as the following: 
41 
 
%nullnullnullnull
nullnullnullnullnullnullnullnull
null %Loss Embedment   (4-3) 
In order to account for the reduction in confining stress at the pile tip associated 
with scour, the end-bearing resistance is reduced by an amount equal to half of the 
proportional loss of embedment due to scour.  This reduction is realistic for piles bearing 
in cohesionless sand and conservative for cemented bearing strata that have significant 
cohesion.  The following equation accounts for percent loss of pile capacity in end-
bearing: 
%nullnullnullnull
nullnullnullnullnullnullnullnullnullnullnull
null
%Lnullnullnull Enullnullnullnullnullnullnullnull
null
               (4-4) 
Using these capacity loss equations, the plunging capacity for timber piles can be 
expressed by the following equations: 
null
nullnullnullnullnullnullnullnull
null null
nullnullnullnullnullnullnullnullnull
?null1nullnull0.75?%nullnullnullnull
nullnullnullnullnullnullnullnull
null0.25?%nullnullnullnull
nullnullnullnullnullnullnullnullnullnullnull
nullnull (4-5) 
null
nullnullnullnullnullnullnullnullnullnullnull
null null
nullnullnullnullnullnullnullnullnull?
null1nullnull0.25?%nullnullnullnull
nullnullnullnullnullnullnullnull
null0.75?%nullnullnullnull
nullnullnullnullnullnullnullnullnullnullnull
nullnull (4-6) 
Equation 4-5 and Equation 4-6 were applied repeatedly for a multitude of driving 
hammer energies, driving resistances, and scour depths; the results are presented in 
Table 4.3.  Note that interpolation between values in the table is permitted.  In order to 
maintain a degree of conservatism, a value of 6 bpi was used as a maximum estimation 
of final driving resistance in Table 4.3.  Note also that hammer energy in Table 4.3 is the 
hammer rated energy multiplied by hammer efficiency.  Two sets of predicted pile 
capacity are provided in the table, one for piles that derive capacity from predominantly 
end-bearing action and one for piles that derive capacity from predominantly side 
friction action.   
42 
 
Values in Table 4.3 reflect a factor of safety of 1.25 used for pile plunging 
capacity.  This factor of safety was used because the variable properties of timber do 
not affect pile plunging.  Rather, the strength properties of the soil profile primarily 
govern pile plunging. 
  
43 
 
Table 4.3 Predicted Pile Capacities Based on Modified Gates Formula for Timber Piles with F.S. = 1.25  
Hammer Energy 
(ft?lb) 
Final Driving Resistance 
(blows/inch) 
Allowable Resistance 
(tons) 
End Bearing Pile Load Capacity 
 (tons) 
(assume 75% tip resistance) 
Friction Pile Load Capacity 
(tons) 
(assume 25% tip resistance) 
% loss of embedment % loss of embedment 
0 20 40 60 80 0 20 40 60 80 
2000 2 1 1 1 1 0 0 1 1 0 0 0 
4000 2 18 18 15 13 11 9 18 15 12 9 5 
6000 2 30 30 26 22 19 15 30 25 19 14 9 
8000 2 41 41 36 31 26 20 41 34 27 19 12 
10000 2 51 51 44 38 32 25 51 42 33 24 15 
12000 2 60 60 52 45 37 30 60 49 39 28 18 
15000 2 71 71 62 53 44 35 71 59 46 34 21 
2000 4 10 10 9 7 6 5 10 8 6 5 3 
4000 4 31 31 27 23 19 15 31 26 20 15 9 
6000 4 47 47 41 35 29 23 47 39 31 22 14 
8000 4 60 60 52 45 37 30 60 50 39 28 18 
10000 4 72 72 63 54 45 36 72 59 47 34 22 
12000 4 83 83 73 62 52 41 83 68 54 39 25 
15000 4 97 97 85 73 61 48 97 80 63 46 29 
2000 6 16 16 14 12 10 8 16 13 10 8 5 
4000 6 39 39 34 29 24 19 39 32 25 19 12 
6000 6 56 56 49 42 35 28 56 46 36 27 17 
8000 6 71 71 62 53 44 35 71 59 46 34 21 
10000 6 84 84 73 63 52 42 84 69 55 40 25 
12000 6 96 96 84 72 60 48 96 79 62 46 29 
15000 6 112 112 98 84 70 56 112 92 73 53 34 
44 
 
Assuming that the loss of plunging capacity is proportional to the loss of pile 
embedment as previously discussed, the critical scour value for which the pile will 
plunge can be determined for a given gravity load of null
nullnullnullnullnullnullnullnullnullnull
.  The critical percent 
loss of scour will be equal to the slope of the pile plunging capacity curve.  An example 
plunging capacity curve is shown below for a 12,000 hammer energy (including hammer 
efficiency) and 4 bpi driving resistance.  Note that the slopes of the curves are linear. 
 
Figure 4.4 Plunging Capacity Curves for 12,000 k-ft Driving Energy, 4 bpi Driving 
Resistance by Modified Gates Formula 
 
Therefore, 
nullnullnullnullnull null
null
nullnullnullnullnull nullnullnullnullnull
nullnull
nullnullnullnullnullnullnullnullnull
%nullnullnullnull nullnullnullnullnullnullnullnullnull
            (4-7) 
0
10
20
30
40
50
60
70
80
90
0% 20% 40% 60% 80% 100%
Capacity
?
(tons)
Loss??of?Embemdent?(%)
Plunging?Capacity?Curve
Fricition
End?
Bearing
45 
 
where the percent loss of embedment used corresponds to the value used to determine 
null
nullnullnullnullnull nullnullnullnullnull
 determined by Equation 4-5 or 4-6 for a friction or end-bearing pile, 
respectively.   
Because the relationship is linear, any percent loss of embedment may be used 
to determine the slope of the curve.  For the screening tool, the pile capacity for 80% 
loss of embedment is used.  Therefore, Equation 4-7 becomes 
%nullnullnullnull nullnullnullnullnullnullnullnullnull
nullnullnullnullnullnullnullnull
null
null
nullnull%nullnullnullnull
nullnull
nullnullnullnullnullnullnullnullnull
null.nullnull
 .             (4-8) 
Critical scour, then, is 
null
nullnull
null %nullnullnullnull nullnullnullnullnullnullnullnullnull
nullnullnullnullnullnullnullnull
?null
nullnull
    (4-9) 
where null
nullnull
 is the length of pile embedded in the soil before the scour event.
46 
 
4.4 Bent Pile Buckling Failure 
 The third failure mode in need of investigation is buckling.  The generic buckled 
shape with coordinate axes is shown below in Figure 4.5.  Recall that to account for the 
effects of varying moments of inertia, shown as null
null
 and null
null
in the figure, an effective 
moment of inertia will be used. 
   
Figure 4.5 Buckled Shape and Coordinate Axes (Ramey et. al 2011) 
 While bracing should be provided for timber pile bents due to the lack of moment 
resistant connections at the cap, both unbraced and braced bents are considered. 
Timber bent piles are not embedded in the bent cap, which is usually timber or 
concrete, but are approximately pinned to the cap.  The screening tool conservatively 
assumes a pinned connection at the cap.  For the pile-to-ground connection, fixity is 
based on the length of embedment.   A total fixity (100%), partial fixity (50%), or pinned 
(0%) fixity condition is assigned based on the following ranges of embedment presented 
in Table 4.4: 
47 
 
Table 4.4 Assumed Fixity Conditions Based on Embedment Length 
Embedment?After?Scour?(ft) Assumed?Fixity Buckling?Coefficient,?C?
??8?ft? 100% 2.0
4???8?ft? 50% 1.5
<?4?ft? 0% 1.0
 Recall that due to the presence of bridge abutments and the connectivity of the 
bridge superstructure to these abutments, bent piles cannot buckle in a sidesway mode 
in the longitudinal direction of the bridge.  Owing to their circular cross-section, timber 
piles have the same moment of inertia, I, in both the longitudinal and transverse 
buckling directions.  Therefore, non-sidesway buckling in the longitudinal direction 
typically controls buckling failure for smaller scour values.   
Due to taper, flexural stiffness of a timber pile decreases exponentially along its 
length.  Therefore, after excessive scour, sidesway buckling in the transverse direction 
below the cross-bracing can occur.  In summary, the following buckling modes are 
considered in the screening tool: 
(1) Non-sidesway buckling in the longitudinal direction of braced and unbraced 
bents; 
           (2) Sidesway buckling in the transverse direction of braced bents below cross- 
     bracing; 
 (3) Sidesway buckling in the transverse direction of unbraced bents.  
 For all buckling modes, the critical buckling mode equation will be a variation of 
the Euler buckling equation. 
 null
nullnull
null
nullnull
null
nullnull
null
null
      (4-10) 
48 
 
The buckling coefficient, C, and buckling length, L, will vary for each mode based on the 
assumed buckling shape and embedment length.  Recall that an effective moment of 
inertia must be used to account for the pile taper, as described in Chapter 3. 
 It should be noted that bridge spans are assumed to be simply supported, as is 
usual for timber bridges. Because of the possibility of transverse sidesway buckling in 
the lower unbraced regions of pile bents after scour, simply supported bridge spans will 
have smaller values of transverse buckling critical loads, null
nullnull
, than continuous span 
bridges because the continuous span superstructure will prevent transverse sidesway 
buckling of the bents.  Also, due to adjacent piles in a bent providing lean-on support to 
other piles in the bent, it is conservative to assume that the critical load for a bent is 
equal to the summation of the critical loads on all piles in that pent 
     null
nullnull
nullnullnullnull
null ?  P
CR
Pnullnullnullnullnullnull.nullnullnullnullnull
nullnullnull
     (4-11) 
For purposes of the screening tool, it was assumed that bridge spans are simply 
supported and that if the most heavily loaded pile in a bent will not buckle, the entire 
bent will not buckle. 
4.4.1 Non-Sidesway Buckling in the Longitudinal Direction 
 For pile buckling in the longitudinal direction for both braced and unbraced bents, 
the following version of Equation 4-10 is used:  
 null
nullnull
null
nullnull
null
nullnull
nullnullnull
nullnullnullnullnullnull.nullnullnull
null
     (4-12) 
The buckling length, L, is assumed to extend from the pile cap to the new ground line 
(NGL).  This length is the addition of the bent height and the scour, minus the pile cap 
height, as shown in Figure 4.6.  The depth of the pile cap is assumed to be 1.25 feet.   
49 
 
 
Figure 4.6 Longitudinal Buckling Failure Mode for Braced and Unbraced Bents 
 For ALDOT engineers, the critical buckling length and corresponding critical 
scour value is of more interest than the critical load.  These values can be determined 
by rearranging Equation 4-12 as follows: 
?
nullnull
null null
nullnull
null
nullnull
nullnullnull
null.nullnull null
nullnullnull
nullnullnullnull
     (4-13) 
null
nullnull
null ?
nullnull
null 1.25nullnull    (4-14) 
The maximum unfactored load on a pile, null
nullnullnull
nullnullnullnull
, is assumed to be known for a particular 
pile.  Note that Equation 4-13 includes a factor of safety of 1.33.   
 The critical scour values and buckling lengths were determined for various pile 
sizes and applied loads, and the results can be seen in Table 4.5.  These results were 
plotted to illustrate their relationship as shown in Figure 4.7.  Note that with increasing 
bent height, the critical scour length decreases.  Therefore, the taller bents will be the 
50 
 
most critical in buckling.  In addition, the critical scour depth is less for a pile with a 
smaller effective diameter.
51 
 
Table 4.5 Critical Longitudinal Buckling Lengths and Critical Scour for Various Bent Parameters (E = 1,800 ksi, F.S. = 1.33) 
Pile?
Fixity,?C?
?????????????????????????Geometric?Parameters
null
nullnullnull
?(in.)? 6? 7 8 9? 10 11 12
null
nullnullnull
?(in
4
)? 64? 118 201 322? 491 719 1018
nullnull
nullnullnull
?(k?in
2
)? 144,500 212,400 361,800 579,600? 883,800 1,294,200 1,832,400
null
nullnullnull
?(kips)?
Critical?Values?(ft)
null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
? null
nullnull
?
1.0?
(Pinned)?
20? 17.2? 18.4?H 23.4 24.6?H 30.5 31.7?H 38.7 39.9?H? 47.7 48.9?H 57.8 59.0?H 68.6 69.8?H
30? 14.0? 15.2?H 19.1 20.3?H 25.0 26.2?H 31.5 32.7?H? 39.0 40.2?H 47.2 48.4?H 56.1 57.3?H
40? 12.1? 13.3?H 16.6 17.8?H 21.6 22.8?H 27.3 28.5?H? 33.8 35.0?H 40.8 42.0?H 48.5 49.7?H
50? 10.8? 12.0?H 14.9 16.1?H 19.3 20.5?H 24.4 25.6?H? 32.0 33.2?H 36.5 37.7?H 43.4 44.6?H
60? 9.89? 11.1?H? 13.5 14.7?H? 17.6 18.8?H? 22.3 23.5?H? 27.6 28.8?H? 33.3 34.5?H? 39.7 41.0?H?
1.5?
(Partial)?
20? 21.1? 22.3?H 28.7 29.9?H 37.4 38.6?H 47.4 48.6?H? 58.4 59.6?H 70.7 71.9?H 84.1 85.3?H
30? 17.2? 18.4?H 23.4 24.6?H 30.6 31.8?H 38.7 39.9?H? 47.7 48.9?H 57.8 59.0?H 68.7 69.9?H
40? 14.9? 16.1?H 20.3 21.5?H 26.4 27.6?H 33.5 34.7?H? 41.3 42.5?H 50.0 51.2?H 59.5 60.7?H
50? 13.3? 14.5?H 18.2 19.4?H 23.7 24.9?H 29.9 31.1?H? 37.0 38.2?H 44.7 45.9?H 53.2 54.4?H
60? 12.1? 13.3?H? 16.6 17.8?H? 21.6 22.8?H? 27.3 28.5?H? 33.8 35.0?H? 40.9 42.1?H? 48.6 49.8?H?
2.0?
(Fixed)?
20? 24.4? 25.6?H 33.1 34.3?H 43.1 44.3?H 54.7 55.9?H? 81.7 68.6?H 97.1 82.9?H 68.6 98.3?H
30? 19.9? 21.1?H 27.0 28.2?H 35.3 36.5?H 44.6 45.8?H? 66.7 56.2?H 79.3 67.9?H 56.1 80.5?H
40? 17.2? 18.4?H 23.4 24.6?H 30.5 31.7?H 38.6 39.8?H? 57.8 48.9?H 68.6 59.0?H 48.5 69.8?H
50? 15.3? 16.5?H 20.9 22.1?H 27.3 28.5?H 34.6 35.8?H? 51.6 43.9?H 61.4 52.8?H 43.4 62.6?H
60? 14.0? 15.2?H? 19.1 20.3?H? 24.8 26.0?H? 31.5 32.7?H? 47.1 40.2?H? 56.2 48.3?H? 39.7 57.4?H?
52 
 
 
Figure 4.7 Critical Scour (null
nullnull 
)
 
versus Bent Height (null) for Longitudinal Buckling of 
Timber Pile Bents (F.S. = 1.33) 
 
0
5
10
15
20
25
30
35
40
0 5 10 15 20
Critical
?
Sc
our
?
Dep
t
h,
?
Scr
?
(ft)
Bent?Height,?H?(ft)
d?=?8?in.
d?=?10?in.
P=?20?kips
P=?40?kips
P=?20?kips
P=?60?kips
P=?40?kips
P=?60?kips
53 
 
4.4.2 Buckling in the Transverse Direction for Braced Bents 
 For bents with low levels of scour, the bracing will prevent sidesway buckling in 
the transverse direction of the bridge.  Therefore, if the piles buckle, it will be non-
sidesway buckling shown as Mode 1 as shown in Figure 4.7.  However, with excessive 
scour, a large length of pile can become exposed below the cross-bracing, allowing for 
sidesway buckling as shown as Mode 2 in Figure 4.8.  By comparing Figure 4.6, non-
sidesway buckling in the longitudinal direction, and Figure 4.8 Mode 1, non-sidesway 
buckling in the transverse direction, it can be determined that for non-sidesway 
buckling, the longitudinal direction will control because its critical buckling length will 
always be longer. 
 
Figure 4.8 Buckling in the Transverse Direction for Braced Bents 
54 
 
 In bents constructed over water, the bottom horizontal brace is located 
approximately 1.25 feet above the water line, rather than 1.25 feet directly above the 
ground line, as shown in Figure 4.9.  In these cases, the buckling length below the 
bracing will include the scour depths, original water depth, null
null
, and the 1.25 feet 
between the water line and the horizontal brace. 
 
Figure 4.9 Critical Buckling Lengths for Braced Bents over Water 
 Equations for determining critical loads for sidesway buckling below the cross-
bracing use another variation of the Euler buckling equation.  The buckling coefficient is 
assumed as 0.5.  The buckling length, L, also only includes the region below the 
horizontal cross-brace.  In addition, the effective section height must be chosen to 
represent the different critical buckling length.  Instead of taking the two-thirds height of 
55 
 
the entire pile length, as with longitudinal buckling, only the transverse critical buckling 
length below the bracing should be used when determining the effective section height.  
This will result in a smaller effective moment on inertia when compared to the 
longitudinal buckling mode.  Therefore, for a bent out of water, the critical load for 
sidesway buckling below the horizontal brace is as follows: 
null
nullnull
null
null.nullnullnull
null
nullnull
nullnullnull
nullnullnullnull.nullnullnull
null
                   (4-15) 
Likewise, the critical load for sidesway buckling below the horizontal brace for a bent 
over water is as follows: 
null
nullnull
null
null.nullnull
null
nullnull
nullnullnull
nullnullnullnull
null
nullnull.nullnullnull
null
           (4-16) 
 The previous two critical load equations were rearranged to determine the critical 
buckling lengths and corresponding critical scour depths for ALDOT screening 
purposes, as was done with buckling in the longitudinal direction.  The resulting 
equation for the critical buckling length is as follows: 
?
nullnull
null null
null.nullnull
null
nullnull
null.nullnull null
nullnullnull
nullnullnullnull
     (4-17) 
A factor of safety of 1.33 is placed on the maximum unfactored pile applied load.  The 
critical scour length is then determined from the following equations.  For a bent out of 
water the critical scour depth is 
null
nullnull
null ?
nullnull
null 1.25.     (4-18) 
For a bent over water, the critical scour depth is 
null
nullnull
null ?
nullnull
null null1.25null null
null
null.    (4-19) 
56 
 
If the maximum estimated scour at the bent is less than the critical scour, the bent is 
assumed safe.   
 The critical buckling lengths and scour depths for various pile geometries and 
applied loads were determined, and are tabulated in Table 4.6.   
Table 4.6 Critical Transverse Sidesway Buckling Lengths and Critical Scour 
Values for Various Braced Bent Parameters (E = 1800 ksi and F.S. = 1.33) 
Pile?
Parameters 
Pile?null
nullnullnull
, null
nullnullnull
, nullnull
nullnullnull
?Values?
null
nullnullnull
 (in) 6 7 8 9 10 11 12 
null
nullnullnull
  (in
4
) 64 118 201 322 491 719 1018 
nullnull
nullnullnull
(kin
2
) 114,500 212,400 361,800 579,600 883,800 1,294,200 1,832,400 
null
nullnullnull
nullnullnullnullnullnullnull 
 
?
(kips) 
null
nullnullnull
?(ft)?Values?
20 12.1 16.6 21.6 27.3 33.8 40.9 48.6 
30 9.92 13.5 17.6 22.3 27.5 33.3 39.7 
40 8.59 11.7 15.3 19.3 23.9 28.9 34.4 
50 7.68 10.5 13.7 17.3 21.3 25.8 30.7 
60 7.01 9.55 12.4 15.8 19.4 23.6 28.0 
null
nullnullnull
nullnullnullnullnullnullnull 
 
?
(kips) 
null
nullnullnull
?(ft)?Values?
20 10.8 15.3 20.3 26.1 32.6 39.7 47.4 
30 8.67 12.2 16.3 21.1 26.3 32.1 38.5 
40 7.34 10.4 14.1 18.1 22.7 27.7 33.2 
50 6.43 9.25 12.5 16.1 20.1 24.6 29.5 
60 5.76 8.30 11.3 14.7 18.2 22.4 26.8 
 
4.4.3 Buckling in the Transverse Direction for Unbraced Bents    
 While timber bents should be cross-braced, some bents are reported as 
unbraced, as shown in Figure 4.10.  In these cases, the critical buckling load is 
determined from the following equation: 
null
nullnull
null
null.nullnullnullnull
null
nullnull
nullnullnull
nullnullnullnullnullnull.nullnullnull
null
                      (4-20) 
The buckling coefficient, C, is assumed to be 0.167 to account for the weak partial fixity 
at the new ground line and the partial rotational resistance at the cap.  The buckling 
57 
 
length is the same as for non-sidesway buckling in the longitudinal direction.  The 
effective section height, then is also determined in the same manner as longitudinal 
buckling, i.e. using the full length of exposed pile after scour. 
 
Figure 4.10 Sidesway Buckling of Unbraced Timber Bents 
 Again, the critical load equation was rearranged to determine critical buckling 
length and scour depth.  The resulting equation, including a factor of safety of 1.33 is as 
follows: 
 ?
nullnull
null null
null.nullnullnull null
null
nullnull
nullnullnull
null.nullnull null
nullnullnull
nullnullnullnull
     (4-21) 
The corresponding critical depth of scour is 
null
nullnull
null ?
nullnull
null 1.25nullnull    (4-2) 
58 
 
The critical scour and buckling lengths for transverse sidesway buckling of 
unbraced bents were determined for various pile sizes and applied loads.  The results 
can be seen in Table 4.7.  ?
Table 4.7 Critical Transverse Sidesway Buckling Lengths and Critical Scour for 
Various Unbraced Bent Parameters (E = 1,800 ksi and F.S. = 1.33) 
Pile?
Parameters 
Pile?null
nullnullnull
, null
nullnullnull
, nullnull
nullnullnull
?Values?
 null
nullnullnull
 (in) 
6 7 8 9 10 11 12 
 null
nullnullnull
  (in
4
) 
64 118 201 322 491 719 1018 
 nullnull
nullnullnull
(k?in
2
) 
114,500 212,400 361,800 579,600 883,800 1,294,200 1,832,400 
null
nullnullnull
nullnullnullnullnullnullnull 
 
?
(kips) 
null
nullnull
?(ft)?Values?
20 7.01 9.55 12.5 15.8 19.4 23.6 28.0
30 5.72 7.80 10.2 12.8 15.9 19.2 22.9
40 4.96 6.75 8.81 11.1 13.8 16.7 19.8
50 4.44 6.04 7.88 9.98 12.3 14.9 17.7
60 4.05 5.51 7.20 9.11 11.2 13.6 16.1
null
nullnullnull
nullnullnullnullnullnullnull 
 
?
(kips) 
null
nullnull
?(ft)?Values?
20 8.26 ? H 10.8 ?H 13.8?H 17.0?H 20.6?H 24.8 ? H 29.2?H
30 6.97 ? H 9.05 ?H 11.4?H 14.0?H 17.1?H 20.4 ? H 24.1?H
40 6.21 ? H 8.00 ?H 10.1?H 12.3?H 15.0?H 17.9 ? H 21.0?H
50 5.69 ? H 7.29 ?H 9.13?H 11.2?H 13.5?H 16.1 ? H 19.0?H
60 5.30 ? H 6.76 ?H 8.45?H 10.4?H 12.4?H 14.8 ? H 17.3?H
 
4.4.4 Summary of Buckling Modes    
 All the equations of buckling for braced and unbraced bents are summarized 
below in Table 4.8.  By comparison of Equation 4-12 (for non-sidesway buckling in the 
longitudinal direction) with Equation 4-20 (for sidesway buckling in the transverse 
direction), it can be determined that transverse sidesway buckling will control for 
unbraced bents due to its identical buckling lengths, but lower C value.  Therefore, the 
screening tool does not consider longitudinal buckling for unbraced bents. 
 
 
59 
 
Table 4.8 Equations of Buckling for Braced and Unbraced Bents 
Bracing?
Scheme?
Buckling?Mode?
Buckling?
Coefficient,?C?
Critical?Buckling?Length
Bent?Not?Over?
Water
Bents?Over?
Water
Braced?
Longitudinal?Non?sidesway 1.0???2.0 H?+?S???1.25?ft Same
Transverse?Sidesway? 0.5? S?+?1.25?ft? S?+?d
w
?+?1.25?ft?
Unbraced?
Longitudinal?Non?sidesway 1.0???2.0 H?+?S???1.25?ft Same
Transverse?Sidesway 0.167 H?+?S???1.25?ft Same
 Note that the effective section height is dependent on the critical buckling length.  
For both non-sidesway buckling in the longitudinal direction and sidesway buckling in 
the transverse direction for unbraced bents, the entire pile length exposed after scour is 
used to determine the effective moment of inertia.  Therefore, the same effective 
moment of inertia would be used.  For sidesway buckling in the transverse direction 
below the horizontal brace (for braced bents) only the pile length below the horizontal 
brace is used to determine the effective moment of inertia.  Therefore, calculations for 
sidesway buckling below the bracing will use a smaller effective moment of inertia. 
4.5 Bent Pushover Failure 
Pushover analysis is a nonlinear analysis procedure first used in seismic 
analyses based on a conventional displacement method of analysis (Daniels et al. 
2007).  Standard elastic and geometric stiffness matrices for the structural elements are 
progressively modified to account for geometric and material non-linearity under 
constant gravity loads and incrementally increasing lateral loads.  For this screening 
tool, the stress-strain curve shown in Figure 4.11 was used to describe the nonlinear 
material behavior of timber. 
60 
 
 
Figure 4.11 Stress-Strain Curve for Nonlinear Pushover of Timber Bents 
Note that with increases in stress above the approximately 4 ksi, the material begins to 
soften before rupture.  An accurate nonlinear analysis must include this material 
nonlinearity.   
Extreme flood water loadings, in conjunction with ever-present gravity loads on a 
bridge pile bent, can be a controlling loading condition if the bent transverse load, F
t
, 
and scour, S, are large as shown in Figure 4.12.  Even for bents that are braced in the 
transverse direction, a significant P-? effect can occur which can induce a bent 
pushover failure in the region from the new ground line (NGL) to the lower horizontal 
brace as indicated in Figure 4.12. 
0
1
2
3
4
5
6
7
8
0 0.004 0.008 0.012 0.016 0.02
Stress,
??
(ksi)
Strain,?? (in/in)
Timber?Stress?Strain?Curve
Rupture?Limit???6?ksi
E???1500?ksi
Rupture?Strain???0.008?in/in
61 
 
 
Figure 4.12 Typical Braced Bent Pushover Failure 
In simple cases, linear eigenvalue analyses may be sufficient for design 
evaluation.  However, the failure of timber bridges subjected to scour may be defined by 
a combination of large deflection instability and material softening or rupture.  Therefore, 
nonlinear incremental analyses were performed using the Riks method to solve for the 
nonlinear equilibrium path (Simulia 2007).  This approach provides solutions regardless 
of whether the response is stable or unstable.  
For this screening tool, the critical pushover load location was assumed to 
correspond to the high water line (HWL) located at the top of the bent, as shown in 
Figure 4.13.  Recall that while the raft is assumed at the top of the bent, the force is 
assumed to act through the centroid of the raft, or 2 feet below the top of the bent. 
Recall that the small and large debris raft forces, null
null
, are 9.72 and 6.48 kips, as 
62 
 
previously determined in Chapter 3.  The assumed typical bent geometry is shown in 
Figure 4.13. 
 
Figure 4.13 Critical Debris Raft Location for Pushover Failure 
A typical pushover load-displacement curve for a braced and unbraced timber 
pile bent is shown in Figure 4.14.  The gravity (P-loads) on the bents are applied before 
the Riks procedure begins, and are held constant through each analysis.  After 
application of the P-loads, the lateral flood water load, F
t
, is incrementally increased 
until the system becomes unstable.  After the initial lateral load increment is provided, 
subsequent iterations and load increments are computed automatically.  After each load 
increment, the bent stiffness matrix is modified to account for changes in geometry due 
63 
 
to deformations of the members of the bent, and to account for the varying stress-strain 
levels occurring in the members.  Thus, both geometric and material nonlinearity of the 
members are included in the analysis; this method provides an accurate evaluation of 
the capacity of the bents.  All the pushover curves produced by the finite element 
software can be seen in Appendix A and B for braced and unbraced bents, respectively. 
Figure 4.14 shows example pushover curves for a 3-pile, 14 in. diameter timber 
pile bent in both the braced and unbraced condition.  The gravity concentrated pile load 
is 20 kips and scour is not present (S = 0 ft).  For the braced pile bent, the pushover 
force (the asymptotic value) is 260 kips.  In the screening tool, then, if the expected 
lateral force from the debris raft is less than 260 kips, the bent is safe from pushover 
failure.  For the unbraced bent, the pushover force is 289 kips.  Note that while the 
unbraced bent reaches a higher pushover load, it withstands 1 inch more deflection 
than the braced bent.  This is indicative of the stiffness provided by braced bents. 
 
 
 
64 
 
 
Figure 4.14 Bent Pushover Curve for 3-Pile, 12 ft Bent Height, 14 in. Pile 
Butt Diameter, 20 kip P-load, and No Scour 
The lateral force, produced by a debris raft, is a function of the span length which 
accumulates debris.  The larger the span length, the larger the debris raft that may 
accumulate on a bent.  Depending on the bridge span lengths, the factored maximum 
applied lateral load will be taken as either 8.62 or 12.93 kips for short and long spans, 
respectively.   
Bent pushover loads obtained from the finite element method analyses are 
presented in Tables 4.10 through Table 4.13 as a set of null
null
nullnullnullnullnullnullnullnull
 tables.  The bent 
scenarios that were analyzed are presented in Table 4.9.   
 
 
 
 
0
50
100
150
200
250
300
350
00.511.522.533.54
Pushover
?
Load
?
(kips)
Lateral?Displacement?(in.)
3?Pile?Bent,?H=12ft,?P?Load=20kips,?Dia=14in
X?Braced
Unbraced
65 
 
Table 4.9 Timber Pile Bent Cases Analyzed for Pushover 
Parameter Scenarios Considered 
Bracing Condition Braced and Unbraced 
Number of Piles in Bent 3, 4, 5 
Height (ft) 8, 12, 16, 20 
Pile Butt Diameter (in) 12, 14 
P-Load Applied (kips) 20, 40, 60 
Scour (ft) 0, 5, 10, 15, 20 
66 
 
Table 4.10 Pushover Loads F
t
 for Braced, 12 in. Pile Butt Diameter Bents 
Number?of?
Piles?in?Bent?
Bent?Height?
(ft)?
Scour?(ft)
Pushover?Loads?(kips)?
Pile?Load?(kips)
20 40 60?
3?
8?
0 250 249 247?
5 150 149 148?
10 113 112 110?
15 99.9 97.7 93.2?
20 85.5 82.9 80.3?
12?
0 256 255 254?
5 167 167 166?
10 108 107 112?
15 122 118 108?
20 98.0 81.4 101?
16?
0 228 227 226?
5 180 191 178?
10 145 137 143?
15 135 132 130?
20 113 109 102?
20?
0 228 227 153?
5 143 174 146?
10 138 127 145?
15 113 110 109?
20 101 97.2 90.1?
4?
8?
0 258 255 253?
5 166 163 160?
10 127 123 121?
15 88.3 86 83.9?
20 72.8 74.1 71.6?
12?
0 278 271 275?
5 166 164 179?
10 146 144 142?
15 109 107 105?
20 91.8 91.4 88.7?
16?
0 284 283 280?
5 166 162 191?
10 155 162 159?
15 105 111 102?
20 118 114 110?
20?
0 198 196 195?
5 189 188 186?
10 156 153 147?
15 147 143 137?
20 128 118 109?
 
 
 
67 
 
Table 4.10 (Continued) Pushover Loads F
t
 for Braced,  
12 in. Pile Butt Diameter Bents 
Number?of?
Piles?in?Bent?
Bent?Height?
(ft)?
Scour?(ft)
Pushover?Loads?(kips)?
Pile?Load?(kips)
20 40 60?
5?
8?
0 256 248 243?
5 162 157 152?
10 97.2 108 99.3?
15 80.2 77.5 74.8?
20 70.2 67.1 64.0?
12?
0 257 253 274?
5 160 158 178?
10 131 131 132?
15 112 105 103?
20 94.1 90.9 87.5?
16?
0 236 230 234?
5 206 191 190?
10 147 159 158?
15 108 106 103?
20 90.7 87.5 84.2?
20?
0 263 247 248?
5 207 206 207?
10 165 158 114?
15 101 146 143?
20 117 109 77.3?
 
68 
 
Table 4.11 Pushover Loads F
t
 for X-Braced, 14 in. Pile Diameter Bents 
Number?of?
Piles?in?Bent?
Bent?Height?
(ft)?
Scour?(ft)
Pushover?Loads?(kips)?
Pile?Load?(kips)
20 40 60?
3?
8?
0 250 249 247?
5 162 161 159?
10 123 122 120?
15 89.3 99.4 86.7?
20 78.7 77.6 76.6?
12?
0 261 260 253?
5 192 191 190?
10 135 130 136?
15 115 113 114?
20 104 99.3 97.9?
16?
0 228 227 226?
5 159 158 157?
10 155 154 155?
15 134 142 140?
20 107 106 104?
20?
0 229 228 227?
5 171 173 178?
10 140 100 138?
15 136 135 133?
20 115 113 119?
4?
8?
0 258 255 252?
5 165 163 160?
10 126 123 121?
15 86.7 85.6 84.1?
20 75.3 73.9 72.0?
12?
0 280 278 277?
5 205 202 202?
10 135 134 133?
15 114 113 111?
20 101 99.1 97.2?
16?
0 283 281 280?
5 190 186 186?
10 162 160 159?
15 119 115 106?
20 103 103 101?
20?
0 215 251 250?
5 149 183 182?
10 161 162 160?
15 147 145 144?
20 134 133 131?
 
69 
 
Table 4.11 (Continued) Pushover Loads F
t
 for-Braced,  
14 in. Pile Butt Diameter Bents 
Number?of?
Piles?in?Bent?
Bent?Height?
(ft)?
Scour?(ft)
Pushover?Loads?(kips)?
Pile?Load?(kips)
20 40 60?
5?
8?
0 253 248 243?
5 162 131 131?
10 97.3 99.3 97.7?
15 85.8 84.4 75.5?
20 69.6 66.9 64.6?
12?
0 254 234 244?
5 172 203 166?
10 130 127 127?
15 123 108 106?
20 96.8 94.7 92.5?
16?
0 236 232 221?
5 238 236 233?
10 147 146 157?
15 123 121 119?
20 105 103 101?
20?
0 275 273 248?
5 228 194 166?
10 163 161 160?
15 114 112 111?
20 131 128 125?
70 
 
Table 4.12 Pushover Loads F
t
 for Unbraced, 12 in. Pile Butt Diameter Bents 
Number?of?Piles?in?Bent? Bent?Height?(ft) Scour?(ft)
Pushover?Loads?(kips)?
Pile?Load?(kips)?
20 40? 60?
3?
8?
0 289 289? 288?
5 163 162? 164?
10 104 102? 98.3?
15 69.4 64.9? 61.0?
20 46.8 41.3? 37.0?
12?
0 183 181? 164?
5 115 108? 99.9?
10 75.6 71.0? 61.5?
15 50.5 46.0? 40.7?
20 29.5 28.8? 23.1?
16?
0 122 120? 107?
5 80.3 78.1? 67.5?
10 53.3 50? 44.9?
15 37.1 31.8? 26.3?
20 19.9 18.4? 12.3?
4?
8?
0 411 231? 408?
5 224 222? 221?
10 133 131? 135?
15 95.2 92.7? 88.1?
20 68.5 47.0? 59.4?
12?
0 289 231? 230?
5 152 153? 148?
10 104 100? 95.9?
15 73.6 68.8? 60.0?
20 55.2 47.0? 43.8?
16?
0 164 155? 154?
5 113 109? 103?
10 63.4 62.7? 68.4?
15 65.3 59.7? 53.5?
20 43.8 38.5? 31.9?
5?
8?
0 501 231? 230?
5 287 153? 149?
10 180 100? 95.9?
15 73.6 68.8? 60.0?
20 55.2 47.0? 43.8?
12?
0 291 290? 288?
5 191 188? 186?
10 132 128? 123?
15 94.5 89.2? 83.8?
20 70.1 63.4? 56.7?
16?
0 210 202? 193?
5 142 139? 148?
10 101 97.4? 61.3?
15 75.5 67.4? 61.3?
20? 58.3? 47.3? 42.4?
 
71 
 
Table 4.13 Pushover Loads F
t
 for Unbraced, 14 in. Pile Butt Diameter Bents 
Number?of?Piles?in?Bent? Bent?Height?(ft) Scour?(ft)
Pushover?Loads?(kips)?
Pile?Load?(kips)?
20 40? 60?
3?
8?
0 495 451? 450?
5 277 276? 275?
10 180 178? 174?
15 121 119? 116?
20 86.7 83.3? 78.6?
12?
0 289 288? 283?
5 198 187? 186?
10 131 129? 125?
15 92.1 89.8? 86.0?
20 67.5 55.2? 58.3?
16?
0 203 208? 206?
5 142 138? 136?
10 97.3 95? 92.4?
15 72.2 64.9? 54.7?
20 46.2 47.2? 41.0?
4?
8?
0 644 643? 642?
5 376 374? 364?
10 242 240? 238?
15 166 164? 161?
20 88.9 85.5? 115.0?
12?
0 410 409? 408?
5 258 258? 257?
10 142 160? 159?
15 129 126? 122?
20 69.0 91.9? 87.0?
16?
0 281 279? 277?
5 191 189? 187?
10 139 136? 131?
15 118 110? 106?
20 54.2 48.7? 68.9?
5?
8?
0 744 743? 741?
5 440 470? 468?
10 289 302? 297?
15 212 206? 203?
20 155 136? 145?
12?
0 501 499? 504?
5 329 327? 324?
10 228 221? 218?
15 166 161? 153?
20 125 119? 111?
16?
0 340 354? 351?
5 231 229? 227?
10 178 172? 163?
15 134 126? 118?
20? 104? 95.4? 88.7?
 
72 
 
4.6 Beam-Column Failure 
 
 The final failure mode that is evaluated is failure of the upstream pile as a beam-
column.  As previously discussed in Section 4.5 for bent pushover, in extreme scour 
events a debris raft may form at a bent, inducing a lateral load.  This lateral load causes 
bending in the upstream pile, while the gravity loads on the bridge cause an axial 
column load.  Thus, the upstream pile functions as a beam-column.  As shown in Figure 
4.15, the critical location for the lateral raft load was determined to be located at the 
center of the cross-bracing (Ramey et al. 2006).  At this section, the stiffness provided 
by the bracing has its least influence and the most bending would be produced by the 
lateral raft force.  
 
Figure 4.15 Beam-Column Failure for Typical Braced Bent 
73 
 
 
In checking the adequacy of the upstream pile as a beam-column, a straight-line 
interaction equation was used: 
null
nullnullnullnullnullnullnull
null
nullnullnullnullnullnullnullnull
null
null
nullnullnullnullnullnullnull
null
nullnullnullnullnullnullnullnull
 null 
null.null
null.null.
     (4-23) 
 Figure 4.16 shows a plot of straight-line ultimate interaction Equation 4-23 
without applying a factor of safety, in addition to an allowable loading straight-line 
interaction equation with a factor of safety of 1.33.  The latter equation is used in the 
screening tool.  Note the factor of safety is not then applied directly to the debris raft as 
previously discussed with the bent pushover analyses. 
 
Figure 4.16 Assumed Ultimate and Allowable Load Interaction Equations 
The axial capacity, null
nullnull
, is governed by either the crushing or buckling load of the 
pile.  The bending capacity, null
null
, is governed by the stress at rupture.  Due to multiple 
74 
 
possible bent geometries and loading conditions, extreme cases for braced and 
unbraced bents were investigated and then the safety of all other cases were 
extrapolated from the results.  These derivations are discussed in this section and may 
also be seen in Appendix C. 
 
4.6.1 Beam-Column Failure Analysis 
 As previously described, the capacities for bending and axial loads are first 
determined, then compared to the applied loads.  For axial capacity it must be 
determined whether crushing or buckling will control.  The crushing stress was assumed 
as 7.0 ksi.  The critical buckling load is determined by the following equation for braced 
bents: 
null
nullnull
null 
nullnull
null
nullnull
nullnullnull
null
null
     (4-24) 
For unbraced bents, the critical buckling load is determined by the following: 
null
nullnull
null 
null.nullnullnull
null
nullnull
nullnullnull
null
null
     (4-25) 
Because buckling is a global phenomenon, the effective moment of inertia is used to 
take the taper into account.   
If the critical buckling stress is less than 7.0 ksi, buckling is assumed to control 
axial capacity.  To convert the crushing stress to a crushing load, the following 
relationship is used: 
 null
nullnullnullnullnullnullnullnull
null null
nullnullnullnullnullnullnullnull
?null
nullnullnullnull
    (4-26) 
Note that crushing load is determined using the cross-sectional area of the pile at the 
base.  Using the base diameter is conservative, due to the decreasing taper.  The 
minimum value of the crushing versus buckling critical load is assumed to control.  For 
75 
 
all timber pile bent cases, buckling controls.  As discussed in Chapter 3, the crushing 
load is 198 kips for even the smallest diameter possible, 6 inches.  The maximum 
considered pile applied load is 60 kips, much lower than the minimum crushing load. 
 For the bending capacity term of the interaction equation, a maximum bending 
moment is produced by the application of the lateral debris raft loading.  For the most 
conservative approach, the smallest cross-section (i.e. at the new ground line) is used 
to determine the rupture moment as follows: 
null
nullnullnullnullnullnullnull
null null
nullnullnullnullnullnullnull
?null
nullnullnullnull
    (4-27) 
where null
nullnullnullnull
 is the section modulus of the pile at the new ground line.  Recall that the 
bending strength of timber is assumed as 12.0 ksi for the purposes of the screening 
tool.  Following this analysis and applying the 1.33 factor of safety, Equation 4-23 was 
rewritten in the following manner: 
null
nullnullnullnull
null
nullnull
null
null
nullnullnull
null
nullnullnullnullnullnullnull
 null 0.75    (4-28) 
 Multiple bent geometries were considered in order to determine the critical scour 
leading to beam-column failure.  The larger debris raft force was initially used for the 
analysis.  If a pile was deemed safe after applying the larger force, it was automatically 
deemed safe for the smaller raft force.  If the pile was found unsafe for the larger raft, 
the smaller raft force case was then investigated.  Note that the unfactored raft loads, 
6.48 kips and 9.72 kips, were used in the analysis since a factor of safety is applied in 
the interaction equation. 
4.6.2 Analysis of Braced Bents 
 The assumed maximum possible scour and the minimum scour (none) were 
investigated for the tallest and heaviest-loaded braced bent considered in the screening 
76 
 
tool.  The analyses for a 20 foot, 3-pile, 12 inch pile diameter bent with a 60 kip load and 
20 feet of scour may be seen in Figure 4.17 (and in Appendix C).  This is the tallest 
braced bent height that is considered in the screening tool, as well as the heaviest 
gravity loading and maximum considered scour value.  Note that the pile is determined 
to be safe; therefore all braced timber bents are considered safe from beam-column 
failure for the screening tool.  The extra stiffness provided by the bracing is effective for 
stability; hence it is recommended that all newly-constructed timber bents be cross-
braced.   
 
 
?
From?the?moment?diagram:
M
F
t
 =?
13
64
9.72kips? 16ft? ?=?31.6?kip ft? ?=?M
Max
M
HB
 =?
3
32
9.72? kips 16? ft?=?14.6?kip ft?
Checking?at?the?locanullon?of?debris?ranull?force?F
t
:
d
F
t
 = 12in 8.5ft 0.12?(?
in
ft
) =?10.98?in
A
F
t
 = 
? 10.98in()
2
?
4
?= 94.7 in
2
S
F
t
 = 
? 10.98in()
3
?
32
 =?130 in
3
Checking?at?horizontal?brace?using?e?ecnullve?secnullon?propernulles:
d
eff
 = 12in 25.83ft 0.12?(?
in
ft
) =?8.90?in I
eff
 = 
? 8.90in()
4
?
64
?= 308 in
4
Also?must?check?P
cr
?for?buckling?in?unbraced?region?exposed?due?to?scour:
P
cr
 = 
2 ?
2
? E? I
eff
?
L
2
 =
2 ?
2
? 1800? ksi 308? in
4
21.5ft 12?()
2
?=?168.3?kips
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
F
t
? ?=12ksi 97.8? in
3
? ?=?97.8?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
F
t
? ?=7ksi 78.3? in
2
? ?=?548.1?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
60 kips?
168.3 kips?
?+??
31.6 kip? ft?
97.8 kip? ft?
?=?0.35?+?0.32?=?0.67?<?0.75???OK!
Figure 4.17 Beam-Column Analysis for 3-Pile Braced Bent
(Bent Height = 20 ft, Scour = 20 ft, Pile Butt Diameter = 12 in.)
77
78 
 
4.6.3 Analysis of Unbraced Bents  
 It was necessary to analyze multiple cases to determine the critical scour for 
unbraced piles considered as beam-columns.  The results of all the beam-column 
analyses are summarized in Table 4.14.  The maximum gravity load, null
nullnullnullnullnull
, that can be 
applied to the pile without beam-column failure is shown in the rightmost column.  A 
?FAIL? designation means the pile is unstable as a beam-column without any gravity 
load. 
Table 4.14 Beam-Column Analysis Evaluations for Multiple Bent Geometries 
Braced?Cases?
Bent?
Height?
(ft)?
Pile?Butt?
Diameter?
(in.)
Scour?
Depth?(ft)?
Raft?
Force?
(kips)
null
nullnullnullnullnull
?
(kips)?
20? 12 20 9.72 60
Unbraced?Cases?
Bent?
Height?
(ft)?
Pile?Butt?
Diameter?
(in.)?
Scour?
Depth?(ft)?
Raft?
Force?
(kips)?
null
nullnullnull
?
(kips)?
8?
12 5 9.72 60
12 10 9.72 FAIL?
14 10 9.72 60
12 10 6.48 26
12?
12 0 9.72 60
12 5 9.72 20
14 5 9.72 60
12 5 6.48 32
12 10 9.27 8.3
14 10 9.72 36
14 10 6.48 44
12 15 9.72 FAIL?
14 15 9.72 FAIL?
 
The calculation of all considered cases may be seen in Appendix C.  
Investigations were limited to unbraced bents less than 12 feet in height and scour 
79 
 
values less than 15 feet.  Because all unbraced bents failed in the beam-column mode 
at 15 feet of scour, it was not necessary to investigate greater depths.  If unbraced 
bents with a height greater than 12 feet are encountered, the engineer may determine 
beam-column adequacy by following the procedure shown in Appendix C using the 
pertinent geometry.  
 
 
 
 
 
CHAPTER 5  
SCREENING TOOL FLOWCHARTS  
5.1 General 
 A more global perspective of the investigative process is useful to understand the 
screening tool.  Flowcharts are included in the chapter to better inform the user of the 
most important calculations needed to determine adequacy and the order these 
calculations will be conducted in the automated screening tool.   
5.2 Screening Tool Macro-Flowchart 
 A macro-flowchart (seen in Figure 5.1) is first included to highlight the five 
possible failure modes and their order of investigation in the screening tool. 
 
 
 
 
 
 
 
 
 
 
80
 
 
	
	
	
	
	
	
	
	
	
	
	
	
		
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
	
Figure 5.1 Screening Tool (ST) Macro-Flowchart 
		
		
	
?Start
PRELIMINARY 
EVALUATION	
KICK-OUT AND 
PLUNGING 
EVALUATION	
Is?bridge?over?water?and?
supported?on?pile?bents??
BENT 
PUSHOVER 
EVALUATION	
Check?bent?piles?for?possible?
pushover?failure?from?combined?
gravity?loading?and?transverse?
flood?water?loading?
BUCKLING 
EVALUATION
1	
2	
3	
4	
5	
UPSTREAM PILE 
BEAM-COLUMN 
EVALUATION	
No?need?to?check?
bent?with?ST.?
Bent?is?OK!
Is?bridge?at?a?site?where?S?>?3?ft?
can?occur?
Have?any?of?bent?piles?lost?
more?than?20%?of?their?original?
cross?sectional?area?in?splash?
zone?or?elsewhere?
Check?bent?piles?for?possible?
kick?out?and?plunging?failures?
Determine?maximum?applied?
pile?and?bent?loads.
Take?immediate?corrective?
action?to?build?up?damaged?
pile?sections.?
Check?bent?upstream?pile?for?
possible?failure?as?a?beam?column?
from?combined?axial?gravity?
loading?and?transverse?flood?water?
loading?on?a?debris?raft.?
Check?bent?piles?for?possible?
buckling?in?longitudinal?and?
transverse?direction?of?the?bent.?
Bent?is?OK!
Yes
Yes
Yes
No
No
No
No?need?to?check?
bent?with?ST.?
81
 
 
5.3 Screening Tool Micro-Flowcharts 
 Micro-flowcharts detailing the procedure for checking each failure mode are 
included in this section.  A schematic of all the flowcharts is shown in Figure 5.2, while 
enlargements of each of the five major blocks of the screening tool are shown in Figures 
5.3 through 5.7 for easier reading.
82
83?
?
 
 
Figure 5.2 Screening Tool Micro-Flowchart Schematic 
   
??
??
?
?
?
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
?????????????
????????????
 
 
 
Figure 5.3 Screening Tool Flowchart Block 1 ? Preliminary Evaluation
START?
Is?bridge?is?over?water?and?is?
in?a?scour?possible?setting??
No?
Bent?is?safe?from?sour?
failure.
Is?maximum?scour?
between?0?and?3?feet??
5
???
?
RH
??
?
No
2
k_v???????
????
?
2
k_v???????
????
?
Determine?bent?pile?and?bent?
maximum?applied?loads.?
No?
Yes
Bent?will?have?a?kick?out?or?
plunging?failure.??Take?corrective?
action?immediately!?
Yes?
ST?cannot?check?the?
adequacy?of?the?bent.??
No
Exit?the?ST.?
Yes?
Yes
Have?bent?piles?lost?more?than?20%?
of?their?original?diameter??
No
Bent?is?safe?from?
scour?failure.?
Yes
Take?corrective?action?to?
build?pile?section?back?to?its?
original?or?greater?diameter.?
Bent?is?safe?from?
scour?failure.?
Bent?piles?have?lost?
more?than?20%?of?
their?original?
diameter??
Take?corrective?
action?to?build?pile?
section?back?to?its?
original?or?greater?
diameter.?
A?
A?
1
PRELIMINARY 
EVALUATION 
No?
Yes 
Does?bent?have?3,?4,?or?5?piles?
in?a?row??
84
   
????
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 5.4 Screening Tool Flowchart Block 2 ? Kick-out and Plunging Evaluation 
A?
Does?pile?have?more?than?2.5?feet?
of?embedment?in?a?firm?soil?after?
scour,?i.e.??null
nullnull
?null?2.5nullnull???
Bent?is?safe?from?kick?out?
failure.?
Check?more?closely?for?
possible?kick?out?failure?
of?piles?or?bent.?
Yes
No
2 
KICK-OUT AND 
PLUNGING 
EVALUATION 
The?following?information?is?known?or?can?reasonably?be?estimated?about?the?
particular?bent?piles:?
(1)??Driving?resistance?in?bpi?at?end?of?driving?(if?unknown,?assume?to?be?2?bpi)?
(2)??Type?of?driving?hammer?and?hammer?driving?energy?(If?unknown,?assume?to?
? be?6?kip?ft)?
(3)??Categorize?as?end?bearing?piles?or?friction?piles?(If?unknown,?assume?piles?are?
? primarily?friction?piles)?
(4)??Pile?embedment?length?before?scour?and?null
nullnullnull
?
(5)??null
nullnullnullnullnullnullnullnullnullnull
?(with?F.S.?=?1.25)??
Use?Table?4.1?in?Chapter?4?to?determine?the?critical?value?of?percentage?loss?of?
embedment.??Multiply?this?value?by?the?length?of?pile?embedment?before?scour,?
null
nullnull
?,?to?determine?the?critical?plunging?scour,?i.e.,?
null
nullnull
null?
%?nullnullnullnull?nullnull?nullnullnullnullnullnullnullnullnull?
nullnullnull
?x?null
nullnull
?
Where??null
nullnull
?includes?F.S.?=?1.25?on?pile?load?capacity.?
Is?null
nullnull
?null?null
nullnullnull
??for?the?site??
Yes 
Piles?or?bent?is?safe?
from?plunging?
failure.?
Bent?should?be?checked?more?
closely?for?possible?plunging?
failure.
Yes No 
B? B?
85
  
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
 
Figure 5.5 Screening Tool Flowchart Block 3 ? Buckling Evaluation
Pile?embedment?after?scour,?null
nullnull
?
For?null
nullnull?
null?8?nullnull???Use?null
null
null 2.00????
For?4?nullnull?? null?null
nullnull
?null ?8?nullnull??Use?null
null
null 1.50???
For??null
nullnull
?null ??4?nullnull???Use?null
null
null 1.00???
B?
1. ?Checking?pile?buckling?in?the?longitudinal?direction?(non?
sidesway?buckling):?
?
null
nullnullnull
null?
null
null
null
null
nullnull
nullnullnull
null
null
??????????????
?
where??null?=?null?+?S???1.25??
? ????null
nullnullnull
?=?Effective?Moment?of?Inertia?
????????????null
null
=?1.0,?1.5,?0r?2.0?based?on?embedment?
or?
????????????null
nullnullnull
=?
null
null
null
null
null
nullnull
nullnullnull
nullnull?null?null
nullnullnullnullnullnullnullnullnullnull
nullnullnullnull
????where?F.S.?=?1.33?
?
??null
nullnullnull
null?null
nullnullnull
null?1.25
?
null?null??
?
?
2. Checking?pile?buckling?in?the?transverse?direction??(sidesway?buckling?below?the?
cross?bracing):?
?
null
nullnullnull
null?
null
null
null
null
nullnull
nullnullnull
null
null
??
?
Where???null?=?Distance?from?nullnull?down?to?the?NGL?
?????????????null?? null null null1.25
?
?nullnullnullnull?nullnullnullnull?nullnullnullnullnull?nullnull?nullnullnullnullnullnull?4.5null?
??nullnullnullnull?null
null
null?1.25
??
nullnullnullnull?nullnullnullnull?nullnullnullnullnull?nullnull?nullnullnullnullnullnull?4.6null?
null
nullnullnull
?=?Effective?Moment?of?Inertia?
null
null
??=?0.5?
or??
null
nullnullnull
=?
null
null.nullnull
null
nullnull
nullnullnull
nullnull?null?null
nullnullnullnullnullnullnullnullnullnull?
nullnullnullnull
????where?F.S.?=?1.33?
?
and,??null
nullnullnull
null?null
nullnullnull
null?1.25
?
null?nullnullnull?nullnullnullnull?null nullnullnull?nullnull?nullnullnullnullnullnull?4.5null??
?
??????????null
nullnullnull
null?null
nullnullnull
null?1.25
?
null?null
null
?nullnullnullnull?nullnullnullnull?nullnullnullnullnull?nullnull?nullnullnullnullnullnull?4.6null?
3. Checking?pile?buckling?in?the?transverse?direction?(sidesway?
buckling?from?the?pile?cap?down?to?the?NGL)?
?
null
nullnull
null
null
null
null
null
nullnull
nullnullnull
null
null
??
?
where????null null null nullnull null1.25
?
??
null
nullnullnull
null?null
null.nullnull?null
nullnullnull
nullnull?nullnullnullnull?nullnullnull?nullnullnullnullnullnullnullnullnull?nullnullnullnull?nullnullnull?nullnullnullnull
??
null
null
?=?1/6?
??
or?
null
nullnull
=?
null
null.nullnullnullnull
null
nullnull
nullnullnull
nullnull?null?null
nullnullnullnullnullnullnullnullnullnull
nullnullnullnull
????where?F.S.?=?1.33?
?
and,?null
nullnull
null?null
nullnull
null?1.25? nullnull??
?
Note:??There?is?no?need?to?check?for?buckling?in?the?
longitudinal?direction?as?sidesway?mode?will?always?
control?in?unbraced?bents.?
?
Controlling?null
nullnull
null?minimum?null
null
nullnullnull
null
nullnullnull
null?
? Then,?is??null
nullnull
nullnull
nullnullnull
????
Bent?is?safe?from?
buckling.
Bent?should?be?checked?more?
closely?for?buckling?failure.?
Then,?is?
?null
nullnull
?null?null
nullnullnull
????
Bent?should?be?checked?
more?closely?for?
buckling?failure.
Bent?is?safe?from?
buckling.?
3
BUCKLING 
EVALUATION 
Does?bent?have?sway?bracing?in?place??
C
C?
No
Yes
Yes
No
Yes
No?
86
   
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
 
Figure 5.6 Screening Tool Flowchart Block 4 ? Bent Pushover Evaluation
C?
Is?there?a?source?or?history?
of?stream?flood?debris?from?
which?a?bent?debris?raft?
could?form??
Pnull?
null
nullnullnullnullnullnullnullnullnullnull
nullnullnullnull
nullnull.nullnull?nullnullnullnullnull?nullnull?nullnullnullnull
?
Determine?load?to?apply?to?bent?cap?above?each?pile?in?
pushover?analysis:??
Bent?is?safe?from?
pushover?failure.
Assume?no?debris?raft?develops?and?
null
null
nullnullnullnullnullnullnullnullnullnull
?=?1.5?kips?
(Includes?a?F.S.?=?1.33)?
Go?to?appropriate?pushover?
load?table?in?the?Appendix?of?
this?report?to?determine?bent?
pushover?force?null
null
Bent?should?be?checked?more?closely?for?
possible?push?over?failure.?
Is??null
null
?null null
null
nullnullnullnullnullnullnullnullnullnull
???
Bent?is?safe?from?
pushover?failure.?
Bent?should?be?checked?
more?closely?for?possible?
pushover?failure.?
4
BENT 
PUSHOVER 
EVALUATION
D?
D?
Yes?
Yes
Yes
No
No
No
Determine?bent?pushover?debris?raft?force?based?on?bridge?
span?length:?
For?null
nullnullnullnull
null?25?ft,?use?null
null
nullnullnullnullnullnullnullnullnullnull
?=?8.62?kips?
For?25?ft??null?null
nullnull
?null?36?ft,?use?null
null
nullnullnullnullnullnullnullnullnullnull
?=?12.93?kips?
Go?to?appropriate?pushover?
load?table?in?the?Appendix?of?
this?report?to?determine?bent?
pushover?force?null
null
?
Is??null
null
nullnull
null
nullnullnullnullnullnullnullnullnullnull
???
87
  
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
Figure 5.7 Screening Tool Flowchart Block 5 ? Upstream Beam-Column 
Evaluation
D?
Upstream?pile?is?safe?as?beam?column.?
5
UPSTREAM PILE 
BEAM-COLUMN 
EVALUATION 
Yes
NOTE:?BEAM?COLUMN?CHECK?EMPLOYS?
A?F.S.?=?1.33?
Is?there?a?source?or?history?of?flood?
debris?such?that?a?debris?raft?could?
form?on?a?bent??
Yes?
Does?bent?have?cross?bracing??
No?
Is?the?bent?height?before?scour?
greater?than?12?ft???
No?
Is?12???H?>?8?ft??
Upstream?pile?is?safe?as?a?beam?column.???
No
ST?cannot?check?adequacy?of?this?bent.?
Yes
Yes
Is?pile?diameter?12in.?or?14in.??
OK?if?scour???5?ft?
for?P???60?kips,??
and?
OK?if?scour???10?ft?
for?P???36?kips.?
OK?if?scour???5?ft?
for?P???60?kips,?
and??
OK?if?scour???10?ft?
for?P???44?kips.
What?is?the?bridge?span??
12?in. 14?in.?
15????L???25?
OK?if?scour???10?ft?
for?all?bridge?span?
lengths.?
Is?pile?diameter?12in.?or?14in.??
OK?if?scour???5?ft? OK?if?scour???5?ft?
for?P???60?kips,??
and?
OK?if?scour???10?ft?
for?P???26?kips.
What?is?the?bridge?span??
12?in.
14?in.?
For?H???8?ft?
No?
15????L???25??
25??<?L???36??
25??<?L???36?
OK?if?scour???5?ft?
for?P???32?kips.?
What?is?the?bridge?span??
15????L???25?
25??<?L???36?
OK?if?scour???5?ft?
for?P???20?kips.?
88
?
89 
 
 
 
 
CHAPTER 6  
AUTOMATION OF THE SCREENING TOOL USING VISUAL STUDIO 
6.1 General  
 The analyses used to produce the manual screening tool provided the framework 
for the computer code used to produce an automated screening tool.  This automation 
was accomplished using Microsoft Visual Studio 2005 and Microsoft Visual Studio 2010 
with Visual Basic (VBA) computer code.  The entire VBA code for the automated 
screening tool can be seen in Appendix D.  Pertinent code subsections in the appendix 
will be cited when necessary for each evaluation.  This chapter describes the operation 
of the automated screening tool, highlighting the assumptions and simplifications used 
in the automated screening tool.  The tool uses a series of forms to gather input from 
the user and then displays the results in subsequent forms.  An example problem for a 
braced timber pile bent will be used to illustrate the tool and the forms in this chapter.  It 
is the same example that was used in the Phase I report (Ramey et al. 2011) for the 
evaluation of a braced bent using the manual screening tool.   
 Before using the screening tool, users should familiarize themselves with this 
chapter.  Improper input may produce results, but the results will be erroneous.  An 
understanding of the analysis procedures utilized will enable the user to gauge whether 
the automated screening tool results are reasonable and credible.  The inclusion of a 
printable output report also provides a means for the user to check whether the desired 
?
90 
 
input was the input actually used by the program.  This output report will be described in 
detail later in the chapter. 
 While the program was developed using Visual Studio 2005 and Visual Studio 
2010, the screening tool can be accessed through an executable program that does not 
use Visual Studio as its platform.  Opening the ?TimberScour? application file will launch 
the tool on any computer that has the ?TimberScour? parent folder.  The opening form is 
shown in Figure 6.1.  The button at the center of the form marked ?BEGIN 
EVALUATION? is first pushed to start the evaluation process.  
 
Figure 6.1 Opening Form for Timber Stability Tool 
  Buttons such as this are used throughout to signal to the program that the user 
has completed the directions and is ready to advance to the next form.  A continue 
(CONTINUE) button is found at the bottom right-hand corner of all subsequent forms.  
?
91 
 
Note that the exit (EXIT) button can be also pressed at any moment during the program, 
closing all forms.  This button can be found in the bottom left-hand corner of each form.  
A help (HELP) icon, indicated by a blue question mark, can also be found in the toolbar 
located at the top of some forms.  The help icon shown in Figure 6.1 will display the 
dialog box shown in Figure 6.2. 
 
Figure 6.2 General Help Dialog Box 
?
92 
 
 The guidance included in HELP dialog boxes reflects the Phase IV report, but 
should not be considered to cover the entire report.  The most important assumptions 
and advice are included.  HELP dialog boxes are to be closed using the OK button 
found at the bottom of the window.  The program will not proceed until the HELP 
window is closed. 
6.2 Preliminary Input Analysis 
 The preliminary evaluation form is used to gather all required input needed to run 
the screening tool.  Also, kick-out susceptibility and section loss issues are determined.  
Input parameters include the following: 
 (1) Whether or not bridge is in a scour possible setting, 
 (2) Span lengths between consecutive bents of the bridge, 
 (3) Number of piles in a bent, 
 (4) Height of the bent (measured from the top of the cap to the OGL), 
 (5) Water depth below bent, 
 (6) Pile butt diameter, 
 (7) Bracing condition, 
 (8)  Pile embedment length, 
 (9) Estimated depth of maximum scour, 
 (10) Presence or non-presence of significant marine borer or rotting issues. 
All required information must be included for subsequent calculations.  The number of 
piles in the bent, pile diameter, and bracing scheme are chosen by drop-down menus.  
Because this is a screening tool, only broad cases of pile diameter and number of piles 
were considered.  Note, one-story bracing is assumed.  While occasional instances of 
?
93 
 
two-story bracing were reported by ALDOT, one-story bracing is a conservative 
assumption.  See the discussion in Section 3.4.  The user should note the required units 
for all properties.  If a bent is not over water, user should input ?0? for the depth of water 
under the bent as indicated on the form.  The preliminary analysis form is shown in 
Figure 6.3. 
 
Figure 6.3 Preliminary Evaluation Form 
For this example, a 16 foot high, 4-pile timber braced bent is used.  The bent is not over 
water, therefore the depth of water under the bent is 0 feet.  The span between bents is 
36 feet (therefore the larger debris raft will accumulate).  The critical pile butt diameter is 
?
94 
 
12 inches.  The length of embedment before scour is 24 feet.  15 feet of scour is 
projected at the site.  No section loss has been reported. 
 If the HELP icon is pressed in the toolbar of the Preliminary Evaluation form the 
dialog box shown in Figure 6.4 will appear. 
 
Figure 6.4 Preliminary Evaluation Help Dialog Box 
 Once all questions have been answered by the user, the enter (ENTER) button 
should be pressed as indicated by the large green arrow on the form.  If any textbox or 
drop-down menu is left blank, subsequent calculations should be considered erroneous.  
?
95 
 
 After pressing the ENTER button, the user will either be directed to continue to 
the next stage of evaluation or given a message box.  This message box, or boxes, will 
display important information that must be noted by the user.  If input parameters are 
outside the scope of the screening tool, the user will be alerted by a message box in the 
center of the screen and advised to exit the screening tool.  If marine borer or rot issues 
have led to substantial section loss, the user will be advised to build the section back up 
to its original diameter in this message box.  Remember, all calculations will use this 
original diameter, therefore all failure modes later designated as safe are contingent on 
the pile being built back to its original diameter.  An example of the critical section loss 
message box can be seen below in Figure 6.5. 
 
Figure 6.5 Example Critical Section Loss Alert Dialog Box 
?
96 
 
 After all dialog boxes have been addressed and closed by pressing the (OK) 
button, the user will be directed to press the continue (CONTINUE) button by the large 
green arrow on the form.  This will open the next form which is used to input the 
maximum applied pile and bent loads.  For this example, the maximum pile applied load 
is 40 kips, while the maximum bent applied load is 160 kips.  The form can be seen 
below in Figure 6.6. 
 
Figure 6.6 Input Form for Maximum Pile and Bent Loads 
Note that the maximum pile load is not necessarily the same as the bent load evenly 
distributed across all the piles.  Not all piles in the bent necessarily have the same load; 
therefore the maximum single pile load is entered in addition to the total bent load.  For 
detailed description of the calculation of these loads, see Chapter 6 of the Phase IV 
Milestone No. 1 Report (Ramey et al. 2011).  Note that loads should be entered as 
unfactored loads and in units of kips.  The HELP dialog box found in the form?s toolbar 
reminds the user of these stipulations.  It can also be seen in Figure 6.7. 
?
97 
 
 
Figure 6.7 Pile and Bent Applied Loads Help Dialog Box 
 In the steel screening tool, a load calculator was included to compute pile and 
bent maximum applied loads.  While this timber screening tool does not include such a 
calculator, the steel screening tool calculator could still be used to determine maximum 
load.  However, the engineer would have to determine equivalent loads to describe the 
weight of the timber bent bridge superstructure in order to do so.  After entering these 
loads, the user is directed to continue to the next form.   
6.3 Kick-out and Plunging Evaluation 
 The next form gathers data used to evaluate plunging and kick-out susceptibility 
of the bent. For plunging evaluation, geometry for multiple piles may be entered rather 
than for only the critical pile.  The information for each pile is assigned to a single 
column.  Not all columns are required to be filled and the user may only input the most 
critical pile in a single column if preferred.  In this case, all columns of data are inputted 
?
98 
 
as shown in Figure 6.8. 
 
Figure 6.8 Plunging Evaluation Form Showing Input 
The pile-driving hammer type is chosen from a drop-down box at the top of the form (in 
this case, a drop hammer).  Values of driving resistance, hammer energy, maximum 
estimated scour depth, and embedment before scour are provided by the user.  The 
most critical pile is located in Column 1 (driving resistance = 5 bpi, hammer energy = 
12,000 ft-lbs, maximum scour = 15 feet, and embedment before scour = 24 feet).  Note 
?
99 
 
that the hammer?s rated energy should be inputted into the form.  The screening tool will 
internally apply a reduction based on the efficiency of that hammer.  Note that if all 
boxes are not filled in a column, the bent will not be evaluated.  This includes the pile 
number label boxes.  If the user requires any guidance on the form, the HELP icon will 
display the dialog box shown in Figure 6.9. 
 
Figure 6.9 Plunging Help Dialog Box 
?
100 
 
Recall that dialog boxes are closed by pressing the OK button.  After characteristics for 
all desired piles have been inputted, the ENTER button is pressed.  The user will first be 
alerted of the kick-out failure evaluation with either a dialog box alerting the user to all 
piles being safe (Figure 6.10), or a series of dialog boxes indicating which piles are 
either unsafe or in danger of being unsafe after multiple scour events (Figure 6.11).  
Recall from Section 4.2 that the critical scour depth for imminent kick-out is 2.5 feet, but 
the critical scour depth for possible danger for future scour events is 5.0 feet. 
 
Figure 6.10 Kick-out Evaluation Dialog Box for All Piles Safe 
?
101 
 
 If kick-out failure was imminent, or could possibly become critical after multiple 
scour events a dialog box such as that is shown in Figure 6.11 would appear.  Note that 
Figure 6.11 is a modified version of the example problem being used in this chapter.  
Rather, it uses different inputs in an effort to show the different dialog box for instructive 
purposes.  To produce this dialog box, the maximum scour for the pile in Column 1 was 
increased from 15 feet to 22 feet, resulting in a new length of embedment after scour of 
2 feet.  Therefore, the length of embedment is less than the critical scour depth (2.5 
feet) and kick-out failure is imminent. 
 
Figure 6.11 Kick-out Evaluation Dialog Box for Certain Piles Unsafe 
?
102 
 
 After closing the kick-out dialog box, or boxes, the plunging evaluation output can 
be easily seen in the bottom half of the form, as seen in Figure 6.12.  Note that the data 
used to produce Figure 6.12 pertains to the original example problem.   
 
Figure 6.12 Plunging Evaluation Form Showing Input and Output 
 The results regarding safety for both an end-bearing pile and a friction pile are 
shown.  Guidance for determination of whether a pile is considered to have primarily 
end-bearing action or friction action was given in Section 4.3.  The critical depth of scour 
?
103 
 
is also provided so engineers can consider future scour issues.  While all the piles in the 
example bent are safe as friction piles, the most critical pile is in Column 1.  The critical 
scour for the end-bearing and friction conditions are 22.0 feet and 15.7 feet, 
respectively.  Both critical scour values are greater than the estimated scour (15 feet), 
therefore the pile is safe in plunging for both conditions.   
 The maximum applied load given by the user can be seen at the bottom of the 
form for comparison to the calculated capacities.  Both the load and the capacities are 
shown in units of tons for easy comparison.  For a pile to be considered adequate, the 
maximum applied load should be less than the plunging capacity.  If the user wishes to 
evaluate another bent, the form?s input and output data can be removed using the clear 
(CLEAR) button at the bottom right-hand corner so the new data may be inputted. 
6.4 Buckling Evaluation 
 No more input is required by the user after continuing from the plunging form.  
Instead, forms will display the input that was used for the analysis without any action by 
the user.  For this reason, it is of utmost importance for the input of the preliminary 
analysis forms to be accurate and complete.  Buckling evaluation and all subsequent 
forms will also show important intermediate calculated values in addition to the failure 
mode safety assessments.  The form shown in Figure 6.13 pertains to the buckling 
evaluation. 
?
104 
 
 
Figure 6.13 Buckling Evaluation Form 
Data that was input previously is echoed in the top half of the form, while the bottom half 
of the form shows calculated results.  The user may note the effective moment of 
inertia, calculated by the program, that corresponds to the given bent geometry and 
?
105 
 
amount of scour.  The controlling buckling failure mode will be either non-sidesway 
buckling in the longitudinal direction, transverse sidesway buckling below the bracing, or 
transverse sidesway buckling from the pile cap to the new ground line for unbraced 
bents.  Finally, the safety check for the user-provided estimated maximum scour value 
is shown at the bottom of the form.  For this example, an effective moment of inertia of 
370 in
4
 was calculated by the tool.  The failure mode was determined to be sidesway 
buckling below the horizontal brace in the transverse direction. 
 The critical unbraced length and corresponding critical scour value are also given 
so the engineer may assess the bent for future scour susceptibility.  The critical buckling 
length was determined to be 34.2 feet and the critical scour value was 19.5 feet.  Note 
the critical buckling length is measured from the pile cap connection to the new ground 
line.  Because the critical scour value (19.5 feet) is greater than the estimated scour 
value (15 feet) the bent is safe in buckling.  The screening tool calculations for the 
critical scour values will be discussed in further detail in Chapter 7.  In this section, 
though, the user may note their location on the automated screening tool form.  
6.5 Pushover Evaluation 
 Much like the buckling form, the given input needed to access the database 
containing the pushover values for various bent configurations is echoed at the top of 
the form, while the results are shown at the bottom of the form.  Based on the span of 
the bridge, either the small or larger debris raft force is shown.  If there is no history of 
debris raft formation at the bridge site, the minimum raft force of 1.5 kips is used.  The 
pushover form is shown in Figure 6.14. 
?
106 
 
 
Figure 6.14 Bent Pushover Evaluation Form 
 As previously discussed, only certain bent geometries were investigated, 
therefore the user will be advised if the bent is outside the range of the screening tool 
applicability for pushover evaluation.  First, the applied gravity load must be estimated.  
Because bent pushover is a global phenomenon, it is recommended that the gravity 
load be equal to the maximum bent load divided by the number of piles. Therefore, all 
piles are loaded evenly with a portion of the maximum bent load.  This is not equal to 
the maximum single pile load, but a lower load.  However, using the maximum pile 
applied load on every pile would be overly conservative.   The calculated load for the 
bent is then rounded up to the nearest case investigated in the screening tool as 20, 40, 
?
107 
 
or 60 kips.  In a similar fashion, the scour depth is rounded to 5, 10, 15, or 20 feet.  The 
user will be alerted if input is outside the range of investigated cases.  The safety 
assessment, in addition to the critical scour value, is provided by the program in the 
bottom half of the form. 
 Note that only scour levels less than or equal to 20 feet were considered in this 
screening tool.  Therefore, all bents pronounced safe by the screening tool may possibly 
fail in pushover for a scour value greater than 20 feet.  Further research would be 
required to determine the safety of these out-of-typical-range values.  This applicability 
range is represented by the screening tool by designation of a critical scour value of 
?Greater than 20 ft?.  For example, in the form above, the critical scour is designated in 
this manner.  Note also that the larger debris raft force, 12.93 kips, was used for the 
analysis because the bent?s span is in the 25-to-36 feet span range corresponding to 
the larger debris raft. 
 
 
 
 
 
 
 
 
 
 
?
108 
 
6.6 Beam-Column Evaluation 
 The final evaluation form for beam-column failure is shown in Figure 6.15. 
 
Figure 6.15 Beam-Column Evaluation Form 
No intermediate calculations are performed by the screening tool program; rather, the 
bent is determined safe based on the conclusions made by the analysis of a broad 
range geometries and pile loadings.  The safety is determined using Figure 5.7, or Block 
5 of the micro-flowchart, discussed in Chapter 5 of this report.  The critical scour value 
for beam-column assessment is also included in the form.   Because only broad cases 
of scour (0, 5, 10, 15, and 20 feet) were investigated, the critical scour is given in terms 
of these values.  Note that a critical scour value of ?0? would indicate that the pile is 
?
109 
 
inherently unstable as a beam-column before any addition of load.  For this example, 
the critical scour is ?Greater than 20ft?.  Recall that the largest scour value considered in 
the analysis was 20 feet.  Therefore, a bent pronounced ?safe? has only been evaluated 
for a specific scour range.  The user, therefore, is alerted that the bent may fail at scour 
depths greater than 20 feet. 
6.7 Conclusions and Output Report 
 The final form of the screening tool, shown in Figure 6.16, is a summary of the 
safety assessments for each of the five possible failure modes. 
 
Figure 6.16 Final Conclusions Form 
The example braced bent was safe for all modes, which is identical to the conclusions 
determined using the manual screening tool in the Milestone Report No.1.  All modes 
?
110 
 
that have been designated as unsafe should be checked more closely.  Because this is 
a simplified screening tool, very conservative assumptions have been made.  A more 
detailed analysis of the failure modes, with more accurate input numbers (i.e. closer to 
actual conditions), may yield a safe evaluation.  Pressing the HELP icon in the toolbar 
will display the dialog box shown in Figure 6.17. 
 
Figure 6.17 Conclusions and Printing Help Dialog Box 
 Using the print (PRINT) button located in the toolbar at the top of this form will 
bring up a new dialog box (shown in Figure 6.18) that will allow the user to print an 
output report of the bent scour analysis. 
?
111 
 
 
Figure 6.18 Printing Form 
 Logistical information such as the engineer performing the analysis, date of 
analysis, bridge identification number (BIN), and bridge location are inputted by the 
user.  In addition, a textbox is supplied at the bottom of the form for miscellaneous 
information.  This textbox is ideal for noting geometric assumptions made by the user, 
issues alerted by the screening tool such as marine rot or borers, and any other 
information deemed necessary for record-keeping purposes.  Pressing the print 
(PRINT) button will display a small preview of the document shown in Figure 6.19. 
?
112 
 
 
Figure 6.19 Print Preview of Printable Output Report 
This window is then maximized to display a full view of the output report.  The user may 
check the input parameters used by the screening tool for correctness.  Pressing the 
printer icon at the top left-hand corner will print the report.  Note that the program 
automatically chooses the default printer on the user?s computer.  The example output 
report is shown in Figures 6.20 and 6.21. 
 
 
 
 
 
 
?
113 
 
 
Figure 6.20 Example Output Report (Page 1 of 2) 
?
114 
 
 
Figure 6.21 Example Output Report (Page 2 of 2) 
115 
 
 
 
 
CHAPTER 7   
AUTOMATIC SCREENING TOOL POST-ANALYSES 
7.1 General 
 In order to check the accuracy of the automated screening tool, various 
scenarios involving multiple bent geometries, pile loads, and scour depths were 
evaluated with the tool.  In the course of these evaluations, patterns emerged for 
different failure modes.  These patterns and the reasoning behind them were 
investigated.  The results will be discussed in this chapter. 
7.2  Buckling Post-Analyses 
 To check the accuracy of the buckling evaluation form, patterns of failure modes 
(either longitudinal non-sidesway or transverse sidesway) were investigated.  This 
investigation was limited to braced bents since all unbraced bents are assumed to fail 
by transverse sidesway buckling.  In addition, a study to verify that the critical scour 
depths predicted by the tool are accurate and conservative was conducted.   
7.2.1 Effects of Pile Embedment Length on Buckling Evaluations of Braced 
Bents 
 Table 7.1 summarizes the results produced by the automated screening tool for 
the buckling evaluation of certain braced bents.  The critical buckling length is measured 
from the pile cap to the new ground line (NGL) for all buckling modes.  Recall that even 
though the buckling length for transverse sidesway buckling only includes the pile 
portion located below the horizontal brace, the screening tool displays this critical 
116 
 
buckling length plus the pile length above the horizontal brace (i.e. the critical buckling 
length, null
nullnull
, is always measured from the pile cap down to the new ground line in the 
screening tool).  This length is more easily measured by ALDOT engineers, and was 
therefore cited to be a preferable output for the automated screening tool.  In addition, 
the buckling lengths, if measured from the same point, are comparable and therefore 
easier for analysis purposes.  The failure mode indicated by the screening tool for all of 
these bents was transverse sidesway buckling below the horizontal brace.  Note that 
the pile embedment length before scour for these cases is large (20 feet). 
Table 7.1 Critical Transverse Sidesway Buckling Lengths and Scour Depths  
for Braced Bents, 12 in. Pile Butt Diameter, 20 ft Pile Embedment 
Bent?
Height,?
H?(ft)?
Scour?
Depth,?
S?(ft)
P?Load?
(kips)?
null
nullnull
?(ft)? null
nullnull
?(ft)?
8?
10?
20 42.3 35.5
30 35.5 28.8
40 31.5 24.8
50 28.8 22.0
60 26.7 20.0
15?
20 39.5 32.8
30 33.3 26.5
40 29.5 22.8
50 27.0 20.3
60 25.1 18.4
12?
10?
20 43.0 32.3
30 36.8 26.1
40 33.2 22.4
50 30.7 19.9
60 28.8 18.1
15?
20 40.3 29.6
30 34.7 23.9
40 31.3 20.6
50 29.0 18.3
60
27.3 16.6
While Table 7.1 shows results for only some bent geometries, many more cases 
of bent height, scour, and gravity loads were investigated for the same initial pile 
embedment length.  In the results of the buckling evaluation of these braced bents, 
117 
 
transverse sidesway buckling was overwhelmingly cited by the screening tool as the 
most critical failure mode.  Further investigation was performed to determine why this 
was the case, and if longitudinal buckling could ever be the critical failure mode. 
 First, Table 7.1 was extended to include the critical scour values and critical 
buckling lengths corresponding to longitudinal buckling failure and these are shown in 
Table 7.2.  The screening tool will only display the values for the critical failure mode 
(transverse sidesway buckling in these cases); therefore the longitudinal buckling critical 
values were hand-calculated using the process described in Section 4.4 for braced 
bents. 
Table 7.2 Critical Scour Values for Transverse and Longitudinal Buckling 
for Braced Bents, 12 in. Pile Butt Diameter, 20 ft Pile Embedment 
Bent?
Height,?
H?(ft)?
Scour?
Depth,?S?
(ft)?
Buckling?
Coefficient,?
C?
P?Load?
(kips)?
Transverse?Buckling Longitudinal?Buckling
null
nullnull
?(ft)? null
nullnull
?(ft)? null
nullnull
?(ft)? null
nullnull
?(ft)?
8?
10? 2.0?
20 42.3 35.5 75.2? 68.5
30 35.5 28.8 61.4? 54.7
40 31.5 24.8 53.2? 46.5
50 28.8 22.0 47.6? 40.8
60 26.7 20.0 43.4? 36.7
15? 1.50?
20 39.5 32.8 60.3? 53.6
30 33.3 26.5 49.3? 42.5
40 29.5 22.8 42.6? 35.9
50 27.0 20.3 38.2? 31.4
60 25.1 18.4 34.8? 28.1
12?
10? 2.0?
20 43.0 32.3 70.6? 60.0
30 36.8 26.1 57.8? 47.0
40 33.2 22.4 50.0? 39.3
50 30.7 19.9 44.7? 34.0
60 28.8 18.1 40.9? 30.1
15? 1.50?
20 40.3 29.6 56.6? 45.8
30 34.7 23.9 46.2? 35.4
40 31.3 20.6 40.0? 29.3
50 29.0 18.3 35.8? 25.0
60 27.3 16.6 32.7? 21.9
118 
 
 As can be seen in Table 7.2, the critical scours for transverse buckling, which are 
shaded, are less than for longitudinal buckling, verifying that the screening tool was 
accurate in citing transverse buckling as the critical buckling failure mode. Notice that 
the critical buckling lengths for transverse buckling also are shorter than the longitudinal 
buckling lengths in every instance.  It should be noted also that the buckling coefficient 
changes from 2.0 to 1.5 with an increase in scour depth from 10 to 15 feet.  With the 
larger scour depth, the fixity condition is no longer valid and a partial fixity becomes 
more realistic. 
 To check the accuracy of the screening tool?s critical scour calculation, the 
corresponding critical load, null
nullnull
, was determined using Equation 4-18 for transverse 
buckling and Equation 4-12 for longitudinal buckling using the critical scour values 
produced by the screening tool shown in Table 7.2.  The results are summarized in 
Table 7.3.  Notice, the given gravity load is equal to the allowable load for transverse 
buckling at the critical scour depth.  This is expected since the critical scour depth 
should correspond to the point where the allowable load is maximized.  At any gravity 
load less than the allowable load, the bent still has unused capacity.  At any gravity load 
greater than the allowable load, the bent is unstable.  The critical scour value 
corresponds to the point where the bent first becomes unstable at the maximum 
estimated gravity load.  The allowable longitudinal buckling load, on the other hand, is 
much greater than the gravity load, again verifying that it does not control because the 
bent still has unused longitudinal buckling capacity.  Recall that the buckling evaluation 
in the screening tool includes a factor of safety of 1.33. 
 
119 
 
Table 7.3 Corresponding Allowable Loads based on Critical Scour 
for Braced Bents, 12 in. Pile Butt Diameter, 20 ft Pile Embedment 
Bent?
Height,?H?
(ft)?
Scour?
Depth,?S?
(ft)?
P?Load?
(kips)?
null
nullnull
?(ft)?
Corresponding?Allowable?
Load,?null
nullnullnullnullnull
?(kips)?
Buckling?Mode?
Transverse Longitudinal?
8?
10?
20 35.5 20.0 60.8?
30 28.8 30.0 86.2?
40 24.8 40.0 110?
50 22.0 50.0 132?
60 20.0 60.0 153?
15?
20 32.8 20.0 44.7?
30 26.5 30.0 63.1?
40 22.8 40.0 80.1?
50 20.3 50.0 95.9?
60 18.4 60.0 111?
12?
10?
20 32.3 20.0 49.8?
30 26.1 30.0 68.1?
40 22.4 40.0 83.9?
50 19.9 50.0 98.7?
60 18.1 60.0 112?
15?
20 29.6 20.0 36.0?
30 23.9 30.0 49.0?
40 20.6 40.0 60.4?
50 18.3 50.0 70.4?
60 16.6 60.0 79.7?
 In order to determine the condition where longitudinal buckling will control, the 
respective equations for transverse and longitudinal buckling loads were compared.  
Longitudinal buckling should be considered the controlling case if its critical load,null
nullnull
null
, is 
less than the critical buckling load for transverse buckling, null
nullnull
null
.  Recalling the equations 
for the critical load for these two buckling failure modes, longitudinal buckling should be 
the critical value for a braced bent if the following condition is satisfied: 
null
nullnull
null
null
null.nullnull
null
nullnull
nullnullnull
null
null
nullnull
null
null
 null
nullnull
null
nullnull
nullnullnull
null
null
nullnull
null
null
nullnull
nullnull
null
           (7-1) 
120 
 
Recall that the buckling coefficient, C, for longitudinal buckling is based on the length of 
embedment as discussed in Section 4.4.  Note the different effective moments of inertia 
for longitudinal buckling and transverse buckling, null
nullnullnull
null
and null
nullnullnull
null
 in Equation 7-1. 
 Instead of considering the controlling failure mode in terms of critical loads, the 
controlling failure mode can be considered in terms of critical unbraced buckling 
lengths.  For longitudinal buckling to control, its unbraced length must be longer than 
the unbraced length for transverse sidesway buckling.  To compare the buckling lengths 
accurately, recall that the effective moment of inertia for transverse sidesway buckling is 
always smaller than that of longitudinal buckling.  The two-thirds of critical buckling 
length will be at a lower height for buckling below the cross-bracing (i.e. for transverse 
buckling).  To account for this condition, the transverse buckling moment of inertia can 
be assumed to be a percentage of the longitudinal buckling moment of inertia.  To 
choose a reasonable value, the differences in the effective moments of inertia were 
investigated.  The results can be seen in Table 7.4. 
Table 7.4 Difference in Effective Moment of Inertia Based on Buckling Mode 
Bent?
Height?
(ft)?
Pile?Butt?
Diameter?
(in.)?
Scour?
Value???
(ft)?
Effective?Moment?of?Inertia?(in?)?
Percent?
Difference?
(%)?
Buckling?Mode?
Transverse?Sidesway?
below?Bracing?
Longitudinal?
20?
12?
20?
222 308 72%?
14? 531 693 77%?
12?
15?
269 367 73%?
14? 620 800 78%?
15?
12?
20?
294 367 80%?
14? 667 800 83%?
 
121 
 
While the smallest percent difference is 72%, it would be overly conservative to assume 
this value as representative of all bents.  Therefore, the effective moment of inertia for 
transverse buckling below the bracing buckling mode was assumed to be approximately 
75% of the longitudinal buckling mode effective moment of inertia.  Equation 7-1, then, 
can be rewritten in terms of one effective moment of inertia. 
null
nullnull
null
null
null.nullnull
null
nullnullnull.nullnullnull
nullnullnullnull
null
nullnull
null
null
 null
nullnull
null
nullnull
nullnullnull
null
nullnull
null
null
nullnull
nullnull
null
       (7-2) 
 With these geometric assumptions, Equation 7-2 can be rearranged resulting in 
the following necessary condition for longitudinal buckling to control: 
null
nullnull
null
null
nullnull
nullnull
null
null
?
null.nullnullnull
null
       (7-3) 
Because the equation was written in terms of an identical effective moment of inertia 
and modulus of elasticity, nullnull
nullnullnull
 could be eliminated from Equation 7-2.  The critical 
condition can be further simplified to the following by substituting the equations for 
critical buckling length provided in Section 4.4. 
nullnull
nullnull
null
null
 nullnullnull
nullnull
null
null
 ?null
null.nullnullnull
null
                 (7-4) 
null null1.25 null nullnull nullnull null1.25null ?null
null.nullnullnull
null
     (7-5) 
Finally, rearranging the equation in terms of a critical bent height necessary for 
longitudinal buckling to control: 
nullnull
nullnullnullnull.nullnullnull
null
null.nullnullnull
null
null nullnull null1.25null .             (7-6) 
If a bent is taller than the critical bent height found using Equation 7-6, longitudinal 
buckling should be the critical failure mode.  Note that the critical bent height depends 
122 
 
on the estimated scour value, S, and the embedment length (which dictates the value of 
the buckling coefficient, C). 
 Table 7.5 was generated using Equation 7-6 for varying scour depths, S, and 
buckling coefficients, C.  Note that these results are based on an assumption of 
identical pile materials and geometries (see Equation 7-2), and that the controlling 
failure mode is that which corresponds to the lower ultimate critical load, null
nullnull
.  For all 
braced bents in which the bent height is greater than or equal to the value in Table 7.5, 
longitudinal buckling will be the controlling failure mode. 
Table 7.5 Critical Bent Heights for Longitudinal Buckling Control                                 
Scour,?S?(ft)
Critical?Bent?Height,?H?(ft)
Buckling?Coefficient,?C
1.0 1.50 2.0
1.25 4.08 5.00 5.77
2.50 4.87 6.25 7.41
5.00 6.46 8.75 10.7
10.0 9.62 13.8 17.2
15.0 12.8 18.8 23.8
20.0 16.0 23.8 30.3
 As can be seen Table 7.5, with increasing scour, the critical bent height also 
increases.  In other words, for larger scour values, bents must be increasingly tall for 
longitudinal buckling to control.  Recalling that the maximum considered scour value 
and bent height are both 20 feet, in order to achieve a fixity for the longitudinal buckling 
mode in the most extreme pile scenario, the pile length would be in excess of 48 feet  
(H + S + null
nullnull
 = 20 ft + 20 ft + 8 ft = 48 ft).  This would be exceptionally long, therefore the 
values in the C = 2.0 column for Table 7.5 would not be representative of most piles.  
Rather, critical values in the C = 1.50 column more closely represent typical timber piles 
and thus are shaded in the table.  Recalling that the minimum bent height considered in 
123 
 
the screening tool is 8 feet, for scour values less or equal to 5 feet (S = 1.25 feet, S = 
2.50 feet, and S = 5.0 feet), longitudinal buckling will typically control based on this C = 
1.50 column because the critical bent height (5.0 feet, 6.25 feet, and 8.75 feet) either 
will or likely will be exceeded.  For the larger scour values (S = 15 feet and S = 20 feet), 
the critical bent height (18.8 feet and 23.8 feet) is not likely to be exceeded, therefore 
transverse buckling will typically control.  While no complete conclusion could be drawn 
on the likelihood of buckling mode control for mid-range scour values (5 feet < S < 15 
feet, in general the larger scour values tend towards transverse buckling while smaller 
scour ten towards longitudinal buckling. 
 From Table 7.5 for critical bent heights, it can also be noted that for increasing 
buckling coefficients, the critical bent height for longitudinal buckling to control also 
increases.  Therefore, transverse buckling will be the predominant failure mode for 
bents with large pile embedments.  (Longer embedments ensure that a ?fixed? condition 
is still viable even after extreme scour events, i.e. a buckling coefficient of 2.0 is 
appropriate).  For example, for 10 feet of scour, the critical bent height for a buckling 
coefficient of 1.0 (pinned) is 9.62 feet, while the critical bent height for a buckling 
coefficient of 2.0 (fixed) is 17.2 feet.  Recalling that the screening tool?s applicable bent 
height range is 8 to 20 feet, most bents will have a height less than the critical height of 
17.2 feet, therefore, most bents will be controlled by transverse buckling. 
 For the example case used in this chapter, bent heights considered were 8 and 
12 feet and the embedment before scour for these bents was 20 feet.  Recall that the 
longitudinal buckling coefficients are 2.0 and 1.5 for 10 feet and 15 feet of scour, 
respectively.  From Table 7.5, the critical bent height for longitudinal buckling control is 
124 
 
17.2 feet if the pile is considered fixed for 10 feet of scour.  For the example case, piles 
were considered still ?fixed? after 10 feet of scour and therefore both example bents 
have pile heights less than the critical bent height of Table 7.5.  This verifies that 
transverse buckling should be the controlling failure mode as indicated by the screening 
tool.  Likewise, after 15 feet of scour, the critical bent height is 18.8 feet according to 
Table 7.5, greater than both example bent heights of 8 and 12 feet.  Again, transverse 
buckling failure should have been the controlling failure mode, verifying the screening 
tool results. 
 In order to further investigate the effect of initial embedment on scour 
susceptibility, the buckling evaluation process was repeated for the same example bent 
geometries previously discussed, but assuming an initial embedment of only 18 feet 
instead of 20 feet.  This change only affected the buckling coefficient for 15 feet of 
maximum estimated scour depth.  The coefficient shifted to a value of 1.0, a pinned 
condition, rather than 1.50, a partially fixed condition.  The results are shown in Table 
7.6.  Note that the same moment of inertia is used, therefore transverse buckling 
lengths and critical scours are identical to those in Table 7.2.  The controlling critical 
scour values are shaded. 
 
 
 
 
 
 
125 
 
Table 7.6 Critical Scour Values for Transverse and Longitudinal Buckling  
for Braced Bents, 12 in. Pile Butt Diameter, 18 ft Pile Embedment 
Bent?
Height,??
H?(ft)?
Scour?
Depth,??
S?(ft)?
Buckling?
Coefficient,?
C?
P?Load?
(kips)?
Transverse?Buckling Longitudinal?Buckling
null
nullnull
?(ft) null
nullnull
?(ft) null
nullnull
?(ft)? null
nullnull
?(ft)
8?
10? 2.0?
20 42.3 35.5 75.2? 68.5?
30 35.5 28.8 61.4? 54.7?
40 31.5 24.8 53.2? 46.5?
50 28.8 22.0 47.6? 40.8?
60 26.7 20.0 43.4? 36.7?
15? 1.0?
20 39.5 32.8 49.3? 42.5?
30 33.3 26.5 40.2? 33.5?
40 29.5 22.8 34.8? 28.1?
50 27.0 20.3 31.2? 24.4?
60 25.1 18.4 28.4? 21.7?
12?
10? 2.0?
20 43.0 32.3 70.6? 60.0?
30 36.8 26.1 57.8? 47.0?
40 33.2 22.4 50.0? 39.3?
50 30.7 19.9 44.7? 34.0?
60 28.8 18.1 40.9? 30.1?
15? 1.0?
20 40.3 29.6 46.2? 35.4?
30 34.7 23.9 37.7? 27.0?
40 31.3 20.6 32.7? 21.9?
50 29.0 18.3 29.2? 18.5?
60 27.3 16.6 26.7? 15.9?
 Notice that longitudinal buckling failure now controls for the highest gravity load 
and the greatest scour depth because of the reduction in the buckling coefficient from 
1.50 (partially fixed) to 1.0 (pinned).  Also notice that in cases where transverse buckling 
still controls, and where C = 1.0, the critical scours for longitudinal buckling are less than 
those in Table 7.2 where a 20 feet embedment was assumed, which is reasonable.  
Additionally, notice that the longitudinal critical scour depth converges towards the 
transverse buckling critical scour depth until it overtakes the transverse buckling critical 
scour depth to become the more critical scour depth towards the bottom of the table. 
126 
 
 As was done with the previous example, the corresponding allowable loads for 
transverse and longitudinal buckling were then calculated using the critical scour 
depths.  The results can be seen in Table 7.7.  All the critical scours (which are shaded 
in the table) correspond to the applied gravity load, indicating that the calculations are 
correct. 
Table 7.7 Corresponding Allowable Loads based on Critical Scour 
for Braced Bent, 12 in. Pile Butt Diameter, 18 ft Pile Embedment 
Bent?
Height,??
H?(ft)?
Scour?
Depth,??
S?(ft)?
P?Load?
(kips)?
null
nullnull
?(ft)
Corresponding?Allowable??
Load,?null
nullnullnullnullnull
?(kips)?
Buckling?Mode?
Transverse Longitudinal?
8?
10?
20 35.5 20.0 60.8?
30 28.8 30.0 86.2?
40 24.8 40.0 109.6?
50 22.0 50.0 132.4?
60 20.0 60.0 152.5?
15?
20 32.8 20.0 29.8?
30 26.5 30.0 42.1?
40 22.8 40.0 53.4?
50 20.3 50.0 63.9?
60 18.4 60.0 73.7?
12?
10?
20 32.3 20.0 49.8?
30 26.1 30.0 68.1?
40 22.4 40.0 83.9?
50 19.9 50.0 98.7?
60 18.1 60.0 111.6?
15?
20 29.6 20.0 24.0?
30 23.9 30.0 32.7?
40 20.6 40.0 40.3?
50 18.3 50.0 67.6?
60 15.9 72.6 60.0?
 
 Note that the longitudinal allowable loads for 15 feet of scour, where the pinned 
condition is now used, are quickly approaching the gravity load.  Notice also that for the 
127 
 
12 foot high bent at higher gravity loads, the longitudinal buckling failure again 
overtakes the transverse buckling load to become the controlling failure mode. 
7.2.2 Effect of the Chosen Effective Moment of Inertia on Critical Scour Depth 
 The critical unbraced length and critical scour results produced by the screening 
tool for various braced and unbraced geometries can be seen in Table 7.8.  Note 
carefully the critical scour values and safety evaluations.  Within a given estimated 
scour, the critical scour values decrease with increasing gravity load.  This is logical, 
since critical load and buckling length are inversely proportional according to the generic 
Euler buckling equation (see Equation 4-10).  In other words, as unbraced length 
available for buckling is increased, the buckling load-carrying capacity will be 
decreased.  Therefore, to carry a higher gravity load, the unbraced length must be 
decreased and, by extension, the scour value must be decreased. 
 
 
 
 
 
 
 
 
 
 
 
128 
 
Table 7.8 Critical Scour Depths for Buckling for Braced and Unbraced Bents  
(16 ft Bent Height, 14 in. Pile Butt Diameter, 20 ft Pile Embedment) 
Bracing?
Scheme?
Bent?
Height,??
H?(ft)?
Scour?
Depth,?
S?(ft)?
P?Load?
(kips)?
null
nullnull
?(ft)? null
nullnull
?(ft)? Safety?
Unbra
c
ed
?
16?
5?
20 30.0 15.3 Safe?
30 24.5 9.8 Safe?
40 21.2 6.5 Safe?
50 19.0 4.3 Unsafe?
60 17.3 2.6 Unsafe?
10?
20 28.1 13.4 Safe?
30 23.0 8.2 Unsafe?
40 19.9 5.2 Unsafe?
50 17.8 3.0 Unsafe?
60 16.2 1.5 Unsafe?
Braced
?
16?
5?
20 61.1 46.4 Safe?
30 52.4 37.6 Safe?
40 47.2 32.4 Safe?
50 43.6 28.9 Safe?
60 41.0 26.2 Safe?
10?
20 58.0 43.2 Safe?
30 49.8 35.1 Safe?
40 44.9 30.2 Safe?
50 41.6 26.9 Safe?
60 39.2 24.4 Safe?
 From Table 7.8 it can also be seen that the critical scour value decreases with an 
increase in estimated scour.  For example, for an unbraced 16 foot tall bent carrying a 
gravity load of 50 kips, the critical scours are 4.3 feet and 3.0 feet for initial estimated 
scour values of 5 and 10 feet, respectively.  However, the critical scour depth should be 
identical for the same bent height and gravity load, regardless of maximum estimated 
scour depth.  Theoretically, there should be a specific critical scour value for a given 
bent geometry, indicating the failure case.  Further investigation was warranted to 
determine the reason for the discrepancy. 
129 
 
 In order to determine the cause of this inconsistency, the effective moment of 
inertia was examined for each case.  The values can be seen in Table 7.9. 
Table 7.9 Effective Moment of Inertia for Varying Scour Depths 
Bent?Height,?H?(ft)? Bracing?Scheme Scour?Depth,?S?(ft)? null
nullnullnull
?(in
4
)?
16?
Unbraced?
5 1168?
10 1025?
Braced?
5 978?
10 853?
Because the buckling evaluation assuming 10 feet of estimated scour has a smaller 
effective moment of inertia than that for 5 feet of scour, its critical scour value is 
decreased.  Recall that moment of inertia is indicative of load-carrying capacity, 
therefore the critical buckling length is necessarily decreased with an increase in scour, 
accounting for the loss in load-carrying capacity.  The culprit for the inconsistent critical 
scour values therefore is timber pile taper, which causes the varying moment of inertia. 
 Recall that an effective section must be chosen to account for pile taper in order 
to perform the buckling analyses.  The effective pile section, according to Section 3.5, is 
located at one-third of the pile height above ground after scour.  Because the selection 
of the effective section depends on the post-scour geometry, the estimated scour 
specified by the user of the automated screening tool will determine the effective 
moment of inertia selected.  This effect is illustrated in Figure 7.1.  The larger estimated 
scour values correspond to a larger exposed length of pile after scour.  This longer 
section will exhibit a smaller effective diameter because of the decreasing taper.  
Therefore, when a larger maximum scour is assumed, a smaller effective moment of 
inertia will be utilized in the screening tool.  
130 
 
 
Figure 7.1 Estimated Scour Effect on Effective Section Selection 
 It should be stressed that this effect does not affect the screening tool?s safety 
evaluation of the bent.  The tool does accurately calculate the buckling capacity for the 
user-provided geometry and scour conditions.  It should be noted that this ?safety? 
assignment applies to the present, or estimated, scour condition.  However, the 
evaluation of future scour events may be unconservative.  A small estimated scour 
value yields a large critical scour, leading the user to believe, for a particular case, that 
the bent can withstand additional scour (up to the critical scour).   
 To further illustrate this effect on critical scour projections, the critical buckling 
lengths and scours for a 20 foot braced bent were estimated, focusing on the cases 
where 60 kips is the maximum applied load as shown in Table 7.10.  For an initial 
maximum estimated scour of 5 feet, the critical scour is calculated as 18.2 feet using an 
effective moment of inertia of 491 in
4
.  However, when an initial maximum estimated 
131 
 
scour of 15 feet is assumed, the critical scour is calculated as 9.8 feet, with an effective 
moment of inertia of 352 in
4
.  All critical scour depths reflect sidesway buckling in the 
transverse direction below the bracing as the controlling failure mode, unless otherwise 
noted.  For the non-sidesway cases, a different effective moment of inertia is used to 
represent the different buckling length associated with the buckling mode as discussed 
in Section 4.4.2. 
Table 7.10 Critical Scour Depths for Buckling for Braced Bent 
(20 ft Bent Height, 12 in Pile Butt Diameter, 20 ft Pile Embedment) 
Bent?
Height,?H?
(ft)?
Scour?
Depth,?S?
(ft)?
P?Load?
(kips)?
null
nullnullnull
?(in
4
) null
nullnull
?(ft)? null
nullnull
?(ft)? Safety?
20?
5?
20
383?
47.3 28.6 Safe?
30 41.8 23.1 Safe?
40 38.6 19.8 Safe?
50 36.4 17.6 Safe?
60 34.7 16.0 Safe?
10?
20
322?
44.8 26.1 Safe?
30 39.8 21.1 Safe?
40 36.8 18.1 Safe?
50 34.8 16.0 Safe?
60 33.3 14.5 Safe?
15?
20
269?
42.5 23.7 Safe?
30 37.9 19.1 Safe?
40 35.1 16.4 Safe?
50
367*?
32.0 13.2 Unsafe?
60 29.2 10.4 Unsafe?
*Non-sidesway buckling controlled                
If the user initially assumed 5 feet of scour and the screening tool then produced 
a critical scour depth of 16.0 feet, the user would assume that the bent would continue 
to be safe until a total 16 feet of scour has been reached.  In other words, the bent could 
withstand about 11 feet of future scour.  However, if the user initially assumed 15 feet of 
initial scour, he or she would determine from the automated screening tool that the bent 
132 
 
is safe only up to a total 10.4 feet of scour and has failed.  In addition, the buckling 
mode changed from sidesway buckling in the transverse direction below the bracing to 
non-sidesway buckling in the longitudinal direction when changing the scour estimation 
from 5 feet to 15 feet.  The change in controlling failure mode results in a change in the 
critical scour depth projection.  Also, while the effective moment of inertia for non-
sidesway buckling (367 in?) is greater than the effective moment of inertia for sidesway 
buckling (269 in?) for the 15 feet-of-scour cases, the effective moment of inertia is still 
less than that assumed for 5 feet of scour (383 in?), causing the critical scour depth to 
additionally decrease. 
 Again, this effect does not imply that the buckling safety evaluations of the 
screening tool are incorrect.  Looking back at the previous example, the screening tool 
produced a critical value of 16.0 feet of scour when given an initial estimate of 5 feet of 
scour.  However, if the tool is given an initial estimate of 15 feet of scour (less than 16.0 
feet) the bent is pronounced correctly ?unsafe?.  Therefore, it should be noted that the 
safety evaluation, designated as ?safe? or ?unsafe?, corresponds to the estimated scour 
value inputted by the user.  When considering future scour events, to determine the 
most conservative critical scour depth, the user should employ an iterative method.  
After an initial critical scour is determined based on the first assumed maximum scour 
depth, the program should be run again using that critical scour depth as the new 
maximum estimated scour depth.  This method will converge on a more reliable critical 
scour depth estimate.  An example is shown in Table 7.11. 
 
 
133 
 
Table 7.11 Iteration Example for Most Conservative Critical Scour Depth 
(14 ft Bent Height, 12 in. Pile Butt Diameter, 30 ft Pile Embedment,  
50 kip P-Load, Braced Bent) 
Trial?
Scour?Depth,?S?
(ft)?
null
nullnullnull
?(in
4
) null
nullnull
?(ft) Safety??
1? 10.0 438.2 18.9 Safe
2? 18.9 323.2 16.1 Unsafe
Using the first critical scour depth projection (18.9 feet) as the new estimated 
scour depth for the second trial yielded a more conservative critical scour depth 
projection of 16.1 feet.  Using 18.9 feet as the new applied estimated scour value 
decreased the effective section height, therefore decreasing the effective moment of 
inertia.  The smaller effective moment of inertia resulted in a loss of buckling capacity.  
Note, even with this new, more conservative estimate, the first trial scour value of 10 
feet would still be considered ?safe?.  Therefore, the first trial did not result in a safety 
evaluation error.  
7.3 Plunging Post-Analyses  
Because plunging is a function of soil interaction with a pile, plunging capacity, 
when determined by the Modified Gates Equation, is not affected by the bent geometry 
or pile diameter.  Rather, it is determined solely by the pile driving practices and the pile 
embedment length.  As discussed in Section 4.3, the pile embedment represents the 
length along which the soil can interact with the pile, therefore any loss of embedment 
corresponds to a loss in plunging capacity.  The larger an estimated scour value, then, 
the greater the loss in plunging capacity.  An example driving log with a 13,000 lb-ft 
drop hammer and an estimated 4 bpi final driving resistance was evaluated using the 
134 
 
automated screening tool, and the results are summarized in Table 7.12.  Failure is 
assumed to occur when the critical scour depth for plunging is less than the estimated 
scour depth.  The unsafe cases are shaded.  For this example case, an initial pile 
embedment of 20 feet was achieved after pile driving.  Notice, the capacities for both 
friction and end-bearing piles decrease with increasing scour depths as expected.  Also, 
note that the friction pile capacities are all smaller, which is expected since the friction 
capacity is more sensitive to soil loss.  Therefore, some cases that are safe as end-
bearing piles are not safe as friction piles.   
Table 7.12 Pile Plunging Capacities and Critical Scours for Plunging Failure 
(4 bpi Final Driving Resistance, 13000 lb-ft Drop Hammer, 20 ft Pile Embedment) 
Estimated?
Scour?
Depth?(ft)?
P?Load?
(kips)?
Friction?Pile End?Bearing?Pile?
null
nullnullnullnullnullnullnullnull
?
(tons)?
null
nullnull
?(ft)
null
nullnullnullnullnullnullnullnull
?
(tons)?
null
nullnull
?(ft)?
5?
20?
39.4?
18.3
42.5?
26.7?
30? 16.1 22.5?
40? 13.8 19.3?
50? 11.5 16.1?
60? 9.3 13.0?
10?
20?
28.4?
18.3
34.7?
26.7?
30? 16.1 22.5?
40? 13.8 19.3?
50? 11.5 16.1?
60? 9.3 13.0?
15?
20?
17.3?
18.3
26.8?
26.7?
30? 16.1 22.5?
40? 13.8 19.3?
50? 11.5 16.1?
60? 9.3 13.0?
While the plunging capacities in Table 7.12 change with the estimated scour 
depth, the critical scour values do not.  They are all the same for each estimated scour 
level.  The critical scours represent the total scour depths at which the pile will plunge, 
135 
 
therefore are independent of the estimated maximum amount of scour.  This trend is 
unlike that observed for the buckling critical scour depths, which were determined to be 
dependent upon estimated scour values due to buckling?s dependence on the effective 
pile diameter.  Plunging, however, is not a function of the pile diameter or, by extension, 
the pile moment of inertia.  There are no issues concerning effective section selection.  
The pile, after driving, has a nominal maximum allowable load, derived by the Gates 
Formula.  The plunging capacities, null
nullnullnullnullnullnullnullnull
 and null
nullnullnullnullnullnullnullnull
, represent the new in-situ 
allowable capacities of a pile after a scour event, be it safe or unsafe.  The larger the 
design load a pile must carry, the more of the initial nominal capacity is needed to resist 
plunging, and therefore, the less loss of embedment the pile can withstand before 
failure.  This loss of embedment is represented by the critical scour value, null
nullnull
.  The 
critical scour depth value, then, decreases with an increase in the gravity load.   
As previously discussed, the degree to which the soil interacts with the pile and 
therefore provides plunging resistance is determined by the driving practices.  The 
higher the resistance at the end of driving, the larger the amount of soil resistance 
mobilized.  The same effect can be assumed for higher hammer energy.  The larger the 
hammer energy during driving, the larger the amount of soil resistance that is mobilized.  
The example cases of Table 7.12 were repeated using a 5 bpi driving resistance, rather 
than 4 bpi.  The results can be seen in Table 7.13.  The friction and end-bearing 
plunging capacities are increased over those in Table 7.12, and, in turn, the critical 
scour depths are increased.  This is expected since more capacity is available, so more 
embedment can be lost due to scour.  The unsafe cases are shaded in Table 7.13 for 
easier identification. 
136 
 
Table 7.13 Pile Plunging Capacities and Critical Scours for Plunging Failure 
(5 bpi Final Driving Resistance, 13000 lb-ft Drop Hammer, 20 ft Pile Embedment) 
Estimated?
Scour?
Depth?(ft)?
P?Load?
(kips)?
Friction?Pile End?Bearing?Pile?
null
nullnullnullnullnullnullnullnull
(tons)
null
nullnull
?(ft)?
null
nullnullnullnullnullnullnullnull
(tons)
null
nullnull
?
(ft)?
5?
20?
43.7?
18.8
47.2?
26.3?
30? 16.7 23.4?
40? 14.7 20.6?
50? 12.6 17.7?
60? 10.6 14.8?
10?
20?
31.4?
18.8
38.4?
26.3?
30? 16.7 23.4?
40? 14.7 20.6?
50? 12.6 17.7?
60? 10.6 14.8?
15?
20?
19.2?
18.8
26.7?
26.3?
30? 16.7 23.4?
40? 14.7 20.6?
50? 12.6 17.7?
60? 10.6 14.8?
 When comparing to the values in Table 7.12, the 1 bpi increase in final driving 
resistance results in one case (S = 10 feet, P = 60 kips in friction) changing from an 
unsafe condition to a safe condition in plunging.  This case is shown in bold, but now 
un-shaded.   
 Plunging capacity is also affected by the estimated pile embedment length 
provided by the user.  Initial embedment length is indicative of the amount of soil 
mobilized during driving.  The example cases in Table 7.13 were repeated using the 
same scour depths and driving log, but with an initial pile embedment of 15 feet instead 
of 20 feet.  The results can be seen Table 7.14.  As before, the unsafe cases are 
shaded.  Only scour depths of 5 and 10 feet were evaluated, since the 15 feet case 
would obviously yield zero plunging capacities for a 15 feet embedment length (i.e. the 
137 
 
embedment would become zero after scour, and thereby the plunging capacity would 
be negligible). 
Table 7.14 Pile Plunging Capacities and Critical Scours for Plunging Failure 
(5 bpi Final Driving Resistance, 13000 lb-ft Drop Hammer, 15 ft Pile Embedment) 
Estimated?
Scour?
Depth?(ft)?
P?Load?
(kips)?
Friction?Pile End?Bearing?Pile?
null
nullnullnullnullnullnullnullnull
(tons)
null
nullnull
?(ft)
null
nullnullnullnullnullnullnullnull
(tons)
null
nullnull
?
(ft)?
5?
20?
39.6?
14.1
44.2?
19.7?
30? 12.5 17.6?
40? 11.0 15.4?
50? 9.5 13.3?
60? 7.9 11.1?
10?
20?
23.3?
14.1
32.6?
19.7?
30? 12.5 17.6?
40? 11.0 15.4?
50? 9.5 13.3?
60? 7.9 11.1?
 The capacities and critical scour values were reduced with the reduced pile 
embedments.  As a result, two cases, designated by shading, that were previously 
determined to be safe (S = 10 feet, P = 50 kips in friction; S = 10 feet, P = 60 kips in 
friction) become unsafe.  In general, when the length of pile embedded is shortened, 
any increase in scour becomes a larger percent loss of embedment.  The larger percent 
loss of embedment results in a greater percentage loss of plunging capacity.  Therefore, 
the capacities and critical scour values are reduced. 
 Finally, the effect of a change in hammer type on plunging capacity was 
investigated.  The cases used for Table 7.14 were repeated using a diesel hammer 
instead of a drop hammer.  Diesel hammers are assumed to have an 80% efficiency 
rate compared to the 50% efficiency rate of a drop hammer.  The same hammer energy 
(13,000 lb-ft) and the same final driving resistance (5 bpi) at the end of driving was 
138 
 
assumed.  Fifteen feet of initial pile embedment before scour was also used.  The 
results can be seen in Table 7.15. 
Table 7.15 Pile Plunging Capacities and Critical Scours for Plunging Failure 
(5 bpi Final Driving Resistance, 13000 lb-ft Diesel Hammer, 15 ft Pile Embedment) 
Estimated?
Scour?
Depth?(ft)?
P?Load?
(kips)?
Friction?Pile End?Bearing?Pile?
null
nullnullnullnullnullnullnullnull
(tons)
null
nullnull
?(ft)
null
nullnullnullnullnullnullnullnull
(tons)
null
nullnull
?
(ft)?
5?
20?
57.6?
15.0
64.4?
21.1?
30? 14.0 19.6?
40? 12.9 18.1?
50? 11.9 16.6?
60? 15.1 10.8?
10?
20?
33.9?
15.0
47.4?
21.1?
30? 14.0 19.6?
40? 12.9 18.1?
50? 11.9 16.6?
60? 15.1 10.8?
 Because the diesel hammer is more efficient, more soil resistance is mobilized 
than with the drop hammer, and therefore the plunging capacities are increased.  This 
increase results in all previously unsafe cases becoming safe. These cases are for S = 
10 feet and P = 50 kips in friction and S = 10 feet and P = 60 kips in friction (the cases 
are indicated in bold, but un-shaded since they are now safe). The percent increases in 
capacity due to the change in hammer type are summarized below in Table 7.16. 
Table 7.16 Percent Increase in Plunging Capacity Based on Hammer Efficiency 
Scour?(ft)?
null
nullnullnullnullnullnullnullnull
?(tons)
Percent?
Increase
null
nullnullnullnullnullnullnullnull
?(tons)
Percent?
Increase?
Drop?
Hammer?
Diesel?
Hammer
Drop?
Hammer
Diesel?
Hammer
5? 39.6? 57.6 45% 44.2 64.4 45%?
10? 23.3? 33.9 45% 32.6 47.4 45%?
  
139 
 
Note that while the effective hammer energy was increased by 60%, the 
capacities were only increased by 45%.   Recall that a loss of pile embedment is 
considered proportional to a loss in plunging capacity.  Hammer energy, however, does 
not exhibit such a dramatic effect.  By inspection of the Modified Gates formula 
(Equation 4-1), hammer energy, E, is raised to the half power, therefore not directly 
proportional to plunging capacity.  Therefore, plunging capacity is more sensitive to 
changes in initial pile embedment length than hammer efficiency. 
7.4 Bent Pushover Post-Analyses 
 Only one case out of the 630 bent pushover scenarios considered was 
determined unsafe.  In addition, this case is only unsafe for the larger raft size 
corresponding to a bridge span length greater than 25 feet.  According to the ALDOT-
provided survey of timber bridges, most bridge spans fall in the 15-to-26 foot range and 
will be considered safe from bent pushover.  This overwhelming safe assessment of 
timber bridges must be established as realistic.  
 Table 7.17 summarizes bent pushover forces for steel bents obtained from a 
previous phase report (Donnee et al. 2008) compared to example timber bent pushover 
forces.  The timber bent pushover values shown correspond to an unbraced 12-inch 
butt diameter, 4-pile bent with and an applied concentrated pile load of 60 kips.  The 
steel pushover values correspond to an unbraced nullnull
nullnullnullnullnull
 4-pile bent also with an 
applied concentrated pile load of 60 kips.  Note that the timber bent is 12 feet tall, while 
the steel bent is 13 feet tall.  Because the bents utilize different geometries, steel and 
timber bents are not precisely analogous.  These bents were chosen as the most 
140 
 
comparable.  Notice that the bent pushover forces for the timber bents are significantly 
larger than those for steel bents.   
Table 7.17 Pushover Forces, null
null
, for 4-Pile Unbraced Steel and  
Timber Bents (P-load = 60 kips) 
Scour?
Depth?
(ft)?
null
null
?(kips)?
Steel?
Pile
Timber?
Pile
0 47.3 230?
5 42.4 148?
10 41.0 95.9?
15 36.7 60.0?
20 29.2 43.8?
Because the lateral force required to cause pushover failure is much larger for 
the timber bent, in general, timber bents could be considered to be laterally stronger 
than the steel bents.  It was concluded that the lateral strength of the timber bents is 
derived from the larger pile embedments that are necessary for the driving of timber 
piles.  The partial fixity at the ground line seems to provide adequate bent pushover 
support.   
 According to the previous report regarding the steel piles, unsafe results were 
often indicated for the pushover failure mode in steel bents, and therefore warranted 
concern.  Upon further investigation of that report, it was noticed that 60 kips was the 
smallest gravity load considered for bent pushover for steel bents.  In the timber 
screening tool, however, 60 kips is the maximum considered gravity load.  Table 7.18 
shows the pushover forces for the same 4-pile steel bent used in the table above.  The 
bent pushover forces for three higher gravity loads are included, in addition to the high 
levels of scour that were considered in the steel screening tool.  The unsafe cases are 
shaded.  Note that the design raft force in the steel screening tool is 12.15 kips.  
141 
 
Table 7.18 Bent Pushover Forces (kips) for Unbraced 4-pile nullnull
nullnullnullnullnull
 Steel Bent 
Scour?Depth?(ft)
Applied?Bent?Gravity?Load?(kips)
60? 100? 140? 160?
0? 47.3 41.7 40.5 38.1
5? 42.4 36.1 32.4 29.6
10? 41.0 35.0 29.6 26.3
15? 36.7 29.0 23.1 19.5
20? 29.2 22.7 16.0 12.8
25? 23.5 16.8 10.5 7.80
 
As can be seen in Table 7.18, the steel bents do not become unsafe until a relatively 
higher gravity load is applied (P = 140 or 160 kips) and the larger scour level (S = 25 
feet) is considered.  It can be concluded that the ?safety? of timber bents in bent 
pushover does not speak to the capacity of the bents themselves, which are not 
especially high, but of the magnitude of the applied bent gravity load.  Because timber 
bridges are typically seen on low-volume roads, applied gravity loads upwards of 100 
kips will not be seen on typical timber bents.  Timber bents also are not subjected to as 
high levels of scour as the steel bents, therefore less instability is introduced from the 
lengthening of exposed pile sections due to embedment loss.   
In addition, it should be noted that in the pushover analysis for steel pile bents 
(specifically steel H-piles), the bent is loaded in its weak axis.  Timber piles, on the other 
hand, are never loaded on a weak axis because one is not present.  Due to their circular 
cross-section, pile orientation has no effect on structural behavior. 
7.5 Beam-Column Post-Analyses 
 The most striking observation from the beam-column analyses is the importance 
of bracing timber bents.  The stiffness provided by the cross-bracing enabled all 
investigated braced bents to be determined safe.  Also, the beneficial effect of a larger 
142 
 
pile butt diameter may be observed.  As can be seen from the results summarized in 
Table 7.19, the 14-inch pile can carry larger loads and withstand larger scour values 
than the 12-inch pile.  For the shorter bent (less than 8 feet), the allowable load for the 
14-inch pile is more than double that of the 12-inch pile.  For the taller bents (between 8 
and 12 feet), the 14-inch pile can withstand twice the amount of scour in addition to a 
larger gravity load. 
Table 7.19 Allowable Scour Depths and Allowable Loads for Beam-Column 
Evaluation for Braced Timber Bents and Large Debris Rafts 
Bent?Height?8?to?12?feet?
Pile?Butt?Diameter?
(in.)?
Allowable?Scour?
(ft)
Allowable?Load?
(kips)
12? 5 32
14? 10 44
Bent?Height?less?than?8?feet?
Pile?Butt?Diameter?
(in.)?
Allowable?Scour?
(ft)
Allowable?Load?
(kips)
12? 10 26
14? 10 60
 
143 
 
 
 
 
CHAPTER 8  
CONCLUSIONS 
 Based on the review of the results of the automated screening tool, the following 
practices are recommended for proper use of the automated screening tool: 
(1) Insure that the timber bent under investigation falls in the applicable range 
of the screening tool (see Figure 3.3). 
(2) Review the printable output report to insure that the user-desired input 
variables were used by the automated screening tool. 
(3) Take note of the assumed geometry of the screening tool (see Figure 3.3), 
especially the location of the horizontal brace 1.25 feet above the original 
ground line (OGL).   
(4) In order to safely evaluate a bent for future scour in regards to buckling 
failure, the critical scour produced by the screening tool with an initial 
scour estimate should be re-evaluated using this critical scour as the new 
initial estimate.  This iteration will insure that the most conservative critical 
scour is determined. 
(5) In regards to piles with severe section loss due to marine borer or rot 
issues, note that the automatic screening tool assumes the original pile 
144 
 
diameter.  ?Safe? evaluations, therefore, are contingent on the pile being 
built up to that original diameter. 
 Based on the limitations of the automated screening described above, it is 
recommended that the following items be addressed in a future research effort: 
(1) Additional bent pushover analyses could be performed for greater lateral 
forces, induced by larger debris rafts or overloads, to verify the 
overwhelming bent pushover safety of timber bents. 
(2) A second level of code could be added to the existing automated 
screening tool buckling evaluation to determine a new moment of inertia 
based on the critical scour value, which could then be used to recalculate 
buckling capacities.  In other words, the program could iterate internally, 
rather than having that accomplished by the user. 
 (3) Section loss could be accounted for in a newer revision of the screening 
tool.  This would be most difficult for the beam-column and bent pushover 
evaluations, where multiple geometries are considered separately.  
However, it could be accomplished by accounting for certain percent 
section losses.  Buckling, on the other hand, would be easily reflected by a 
blanket reduction in the effective moment of inertia.  No change would be 
required for the buckling equations.  Plunging and kick-out are 
independent of section loss, so they would not need to be included in this 
modification 
145 
 
(4) Two-story bracing could also be considered in a newer revision of the 
screening tool if needed.  The same difficulties that apply to including 
section loss apply to two-story bracing.  Namely, the multitude of 
geometric cases considered separately for beam-column and bent 
pushover to account for two-story conditions would make the process 
quite lengthy. 
(5) Further finite element analyses could be performed comparing a tapered 
pile and its analogous constant effective section pile In order to validate 
the effective section approach used in the screening tool.   
?
146 
 
 
 
 
REFERENCES 
AASHTO.   LRFD Bridge Design Specifications (4th Ed.).  2007.  American Association 
of State Highway and Transportation Officials.  Washington, D.C. 
Bennett, Caroline R., Cheng Lin, Ryan Parsons, and Jie Han.  2009.  Evaluation of 
behavior of a laterally loaded bridge pile group under scour conditions, Structures 
2009: Don?t Mess with Structural Engineers.  American Society of Civil 
Engineers. 
Bowles, J.E.  1968.  Foundation Analysis and Design.  New York:  McGraw-Hill Book 
Company. 
Chellis, R. D.  1961.  Pile Foundations (2nd Ed.).  New York:  McGraw-Hill Book 
Company. 
Daniels, Joslyn, Doug Hughes, George E. Ramey, and Mary L. Hughes.  May 2007.  
Effects of bridge pile bent geometry and levels of scour and P loads on bent 
pushover loads in extreme flood/scour events.  Practice periodical on structure 
design and construction.  American Society of Civil Engineers. 
Donnee, N., M.L. Hughes, G.E. Ramey, N. Walker, and D. A. Brown.  July 2008. 
Stability of Highway Bridges Subject to Scour ? Phase III ? Part II, Alabama 
Department of Transportation Project No. 930-674.  Auburn University, Alabama:  
Highway Research Center. 
?
147 
 
Federal Highway Administration.  2004.  Bridges, Structures, and Hydraulics.  National 
Bridge Inspection Standards.  Washington:  Government Printing Office. 
Halvorson, Michael.  2006.  Microsoft Visual Basic 2005: Step by Step. Redmond, 
Virginia:  Microsoft Press. 
Hughes, Doug, George E. Ramey, and Mary L. Hughes.  May 2007.  Effects of extreme 
scour and soil subgrade modulus on bridge pile bent buckling.  Practice 
periodical on structural design and construction.  American Society of Civil 
Engineers. 
Hunt, Beatrice E.  2005.  Scour monitoring programs for bridge health.  Transportation 
Research Record:  Journal of the Transportation Research Board CD 11-S:  531-
536.  Washington:  Transportation Research Board of the National Academies. 
Lin, Cheng, Caroline Bennett, Jie Han, and Robert L. Parsons.  2012.  Integrated 
analysis of the performance of pile-supported bridges under scoured conditions.  
Engineering Structures 36:  27-38. 
Maddison, Brian.  2012.  Scour failure of bridges.  Forensic Engineering 165, Issue FE1:  
39-52. 
McConnell, Jennifer Righman and Michael Cann.  2011.  Coupled field monitoring and 
structural analysis to assess scour conditions.  Journal of Performance of 
Constructed Facilities.   American Society of Civil Engineers.  (in press). 
Ramey, G.E. and A.P. Hudgins.  June 1975.  Modification of pile capacity and length 
prediction equations based on historical Alabama pile test data.  Alabama 
Department of Transportation HPR Report No. 75. 
?
148 
 
Ramey, G.E. and D.A. Brown.  2004. Stability of Highway Bridges Subject to Scour - 
Phase I, Alabama Department of Transportation Project No. 930-585, Final 
Report.  Auburn University, Alabama:  Highway Research Center. 
Ramey, G.E., D.A. Brown, D. Hughes, J. Daniels, and L. Agnew.  2006.  Stability of 
Highway Bridges Subject to Scour - Phase II, Alabama Department of 
Transportation Project No. 930-608, Final Report.  Auburn University, Alabama:  
Highway Research Center. 
Ramey, G.E., D.A. Brown, M.L. Hughes, D. Hughes, J. Daniels.  2007.  Screening Tool 
to Access Adequacy of Bridge Pile Bents during Extreme Flood/Scour Events. 
ASCE: Practice Periodical on Structural Design and Construction 12, no. 2:  109-
121. 
Ramey, G.E., M.L. Hughes, D.A. Brown, N. Donnee, and N. Walker.  May 2008. 
Stability of Highway Bridges Subject to Scour - Phase III ? Part 1, Alabama 
Department of Transportation Project No. 930-674.  Auburn University, Alabama:  
Highway Research Center. 
Ramey, G.E., M.L. Hughes, Mary Schambeau, Junsuk Kang, and James S. Davidson.   
2011.  Stability of Highway Bridges Subject to Scour ? Phase IV ? Part 1, 
Alabama Department of Transportation Project No. 930-776.  Auburn University, 
Alabama:  Highway Research Center. 
Shaeffer, R.E.  1980.  Building Structures: Elementary Analysis and Design.  
Englewood Cliffs, New Jersey:  Prentice-Hall Inc. 
Simulia.  ABAQUS Analysis User?s Manual.  Version 6.7.  2007.  ABAQUS, Inc. 
?
149 
 
Quintero, P.S.  March 1980.  Windspeed Analysis of the North Birmingham, Alabama 
Tornado of April 4, 1977.  MSCE Thesis, Auburn University. 
Yu, Wei and Wei Zheng.  2012.  Probabilistic computational framework for detecting 
bridge scour damages based on in-situ measurement.  TRB 2012 Annual 
Meeting.  Transportation Research Board.  (in press). 
Zmeu, Bogdan, P.E.  April 2012.  Evaluation of timber foundation piling in marine 
applications:  knowledge based computerizes algorithms for pile evaluation 
analysis.  Structure Magazine. 
 
150 
 
 
 
 
 
 
APPENDIX A 
 
 
 
 
 
 
 
X-Braced Timber Pile Bent  
F
t  
vs ? Pushover Curves  
 
 
 
 
 
 
 
151 
 
 
Figure A.1 Pushover Curves for X-Braced 3-Pile Bent, H=8ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=8ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
152 
 
  
Figure A.2 Pushover Curves for X-Braced 3-Pile Bent, H=8ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=8ft, P-Load=40kips, Dia=14in
Scour = 0ft 
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
153 
 
  
Figure A.2 Pushover Curves for X-Braced 3-Pile Bent, H=8ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=8ft, P-Load=40kips, Dia=14in
Scour = 0ft 
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
154 
 
  
Figure A.3 Pushover Curves for X-Braced 3-Pile Bent, H=8ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=8ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
155 
 
 
Figure A.4 Pushover Curves for X-Braced 3-Pile Bent, H=8ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=8ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
156 
 
 
Figure A.5 Pushover Curves for X-Braced 3-Pile Bent, H=8ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=8ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
157 
 
 
Figure A.6 Pushover Curves for X-Braced 3-Pile Bent, H=8ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=8ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
158 
 
 
Figure A.7 Pushover Curves for X-Braced 3-Pile Bent, H=12ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9 10
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=12ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
159 
 
 
Figure A.8 Pushover Curves for X-Braced 3-Pile Bent, H=12ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=12ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
160 
 
 
Figure A.9 Pushover Curves for X-Braced 3-Pile Bent, H=12ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=12ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
161 
 
 
Figure A.10 Pushover Curves for X-Braced 3-Pile Bent, H=12ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=12ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
162 
 
 
Figure A.11 Pushover Curves for X-Braced 3-Pile Bent, H=12ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=12ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
163 
 
 
Figure A.12 Pushover Curves for X-Braced 3-Pile Bent, H=12ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16 18
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=12ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
164 
 
 
Figure A.13 Pushover Curves for X-Braced 3-Pile Bent, H=16ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8 9 10
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=16ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
165 
 
 
Figure A.14 Pushover Curves for X-Braced 3-Pile Bent, H=16ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8 9 10
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=16ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
166 
 
 
Figure A.15 Pushover Curves for X-Braced 3-Pile Bent, H=16ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8 9 10
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=16ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
167 
 
 
Figure A.16 Pushover Curves for X-Braced 3-Pile Bent, H=16ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 2 4 6 8 10 12 14 16 18 20
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=16ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
168 
 
 
Figure A.17 Pushover Curves for X-Braced 3-Pile Bent, H=16ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=16ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
169 
 
 
Figure A.18 Pushover Curves for X-Braced 3-Pile Bent, H=16ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=16ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
170 
 
 
Figure A.19 Pushover Curves for X-Braced 3-Pile Bent, H=20ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=20ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
171 
 
 
Figure A.20 Pushover Curves for X-Braced 3-Pile Bent, H=20ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0 2 4 6 8 10 12 14
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=20ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
172 
 
 
Figure A.21 Pushover Curves for X-Braced 3-Pile Bent, H=20ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0 2 4 6 8 10 12 14
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=20ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
173 
 
 
Figure A.22 Pushover Curves for X-Braced 3-Pile Bent, H=20ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=20ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
174 
 
 
Figure A.23 Pushover Curves for X-Braced 3-Pile Bent, H=20ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=20ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
175 
 
 
Figure A.24 Pushover Curves for X-Braced 3-Pile Bent, H=20ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
20
40
60
80
100
120
140
160
180
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 3-Pile Bent, H=20ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
176 
 
 
Figure A.25 Pushover Curves for X-Braced 4-Pile Bent, H=8ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=8ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
177 
 
 
Figure A.26 Pushover Curves for X-Braced 4-Pile Bent, H=8ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=8ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
178 
 
 
Figure A.27 Pushover Curves for X-Braced 4-Pile Bent, H=8ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=8ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
179 
 
 
Figure A.28 Pushover Curves for X-Braced 4-Pile Bent, H=12ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 4-Pile Bent, H=12ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
180 
 
 
Figure A.29 Pushover Curves for X-Braced 4-Pile Bent, H=12ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=12ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
181 
 
 
Figure A.30 Pushover Curves for X-Braced 4-Pile Bent, H=12ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brarced 4-Pile Bent, H=12ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
182 
 
 
Figure A.31 Pushover Curves for X-Braced 4-Pile Bent, H=16ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=16ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
183 
 
 
Figure A.32 Pushover Curves for X-Braced 4-Pile Bent, H=16ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=16ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
184 
 
 
Figure A.33 Pushover Curves for X-Braced 4-Pile Bent, H=20ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=16ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
185 
 
 
Figure A.34 Pushover Curves for X-Braced 4-Pile Bent, H=20ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 4-Pile Bent, H=20ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
186 
 
 
Figure A.35 Pushover Curves for X-Braced 4-Pile Bent, H=20ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 4-Pile Bent, H=20ft, P-Load=40kips, Dia=14in
Scour = 0ft 
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
187 
 
 
Figure A.36 Pushover Curves for X-Braced 4-Pile Bent, H=20ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 4-Pile Bent, H=20ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
188 
 
 
Figure A.37 Pushover Curves for X-Braced 4-Pile Bent, H=8ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=8ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
189 
 
 
Figure A.38 Pushover Curves for X-Braced 4-Pile Bent, H=8ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=8ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
190 
 
 
Figure A.39 Pushover Curves for X-Braced 4-Pile Bent, H=8ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=8ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
191 
 
 
Figure A.40 Pushover Curves for X-Braced 4-Pile Bent, H=12ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=12ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
192 
 
 
Figure A.41 Pushover Curves for X-Braced 4-Pile Bent, H=12ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=12ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
193 
 
 
Figure A.42 Pushover Curves for X-Braced 4-Pile Bent, H=12ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=12ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
194 
 
 
Figure A.43 Pushover Curves for X-Braced 4-Pile Bent, H=16ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16 18
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 4-Pile Bent, H=16ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
195 
 
 
Figure A.44 Pushover Curves for X-Braced 4-Pile Bent, H=16ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16 18
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=16ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
196 
 
 
Figure A.45 Pushover Curves for X-Braced 4-Pile Bent, H=20ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16 18
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 4-Pile Bent, H=16ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
197 
 
 
Figure A.46 Pushover Curves for X-Braced 4-Pile Bent, H=20ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 4-Pile Bent, H=20ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
198 
 
 
Figure A.47 Pushover Curves for X-Braced 4-Pile Bent, H=20ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 4-Pile Bent, H=20ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
199 
 
 
Figure A.48 Pushover Curves for X-Braced 4-Pile Bent, H=20ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 4-Pile Bent, H=20ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
200 
 
 
Figure A.49 Pushover Curves for X-Braced 5-Pile Bent, H=8ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 5-Pile Bent, H=8ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
201 
 
 
Figure A.50 Pushover Curves for X-Braced 5-Pile Bent, H=8ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 5-Pile Bent, H=8ft, P-Load=40kips, Dia=14in
Scour = 0ft 
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
202 
 
 
Figure A.51 Pushover Curves for X-Braced 5-Pile Bent, H=8ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 5-Pile Bent, H=8ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
203 
 
 
Figure A.52 Pushover Curves for X-Braced 5-Pile Bent, H=12ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 5-Pile Bent, H=12ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
204 
 
 
Figure A.53 Pushover Curves for X-Braced 5-Pile Bent, H=12ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=12ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
205 
 
 
Figure A.54 Pushover Curves for X-Braced 5-Pile Bent, H=12ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8 9
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brarced 5-Pile Bent, H=12ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
206 
 
 
Figure A.55 Pushover Curves for X-Braced 5-Pile Bent, H=16ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=16ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
207 
 
 
Figure A.56 Pushover Curves for X-Braced 5-Pile Bent, H=16ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=16ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
208 
 
 
Figure A.57 Pushover Curves for X-Braced 5-Pile Bent, H=20ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0 1 2 3 4 5 6 7 8
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=16ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
209 
 
 
Figure A.58 Pushover Curves for X-Braced 5-Pile Bent, H=20ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=20ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
210 
 
 
Figure A.59 Pushover Curves for X-Braced 5-Pile Bent, H=20ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=20ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
211 
 
 
Figure A.60 Pushover Curves for X-Braced 5-Pile Bent, H=20ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=20ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
212 
 
 
Figure A.61 Pushover Curves for X-Braced 5-Pile Bent, H=8ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 5-Pile Bent, H=8ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
213 
 
 
Figure A.62 Pushover Curves for X-Braced 5-Pile Bent, H=8ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 5-Pile Bent, H=8ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
214 
 
 
Figure A.63 Pushover Curves for X-Braced 5-Pile Bent, H=8ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 5-Pile Bent, H=8ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
215 
 
 
Figure A.64 Pushover Curves for X-Braced 5-Pile Bent, H=12ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=12ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
216 
 
 
Figure A.65 Pushover Curves for X-Braced 5-Pile Bent, H=12ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=12ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
217 
 
 
Figure A.66 Pushover Curves for X-Braced 5-Pile Bent, H=12ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=12ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
218 
 
 
Figure A.67 Pushover Curves for X-Braced 5-Pile Bent, H=16ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 5-Pile Bent, H=16ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
219 
 
 
Figure A.68 Pushover Curves for X-Braced 5-Pile Bent, H=16ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=16ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
220 
 
 
Figure A.69 Pushover Curves for X-Braced 5-Pile Bent, H=20ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 2 4 6 8 10 12
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=16ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
221 
 
 
Figure A.70 Pushover Curves for X-Braced 5-Pile Bent, H=20ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16 18
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Braced 5-Pile Bent, H=20ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
222 
 
 
Figure A.71 Pushover Curves for X-Braced 5-Pile Bent, H=20ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14 16 18
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=20ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
223 
 
 
Figure A.72 Pushover Curves for X-Braced 5-Pile Bent, H=20ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 2 4 6 8 10 12 14
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
X-Brraced 5-Pile Bent, H=20ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
224 
 
 
 
 
 
 
 
APPENDIX B 
 
 
 
 
 
 
 
Unbraced Timber Pile Bent 
F
t  
vs ? Pushover Curves 
225 
 
 
Figure B.1 Pushover Curves for Unbraced 3-Pile Bent, H=8ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=8ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
226 
 
 
Figure B.2 Pushover Curves for Unbraced 3-Pile Bent, H=8ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=8ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
227 
 
 
Figure B.3 Pushover Curves for Unbraced 3-Pile Bent, H=8ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=8ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
228 
 
 
Figure B.4 Pushover Curves for Unbraced 3-Pile Bent, H=12ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
20
40
60
80
100
120
140
160
180
200
0 5 10 15 20 25 30 35 40 45 50
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=12ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
229 
 
 
Figure B.5 Pushover Curves for Unbraced 3-Pile Bent, H=12ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
20
40
60
80
100
120
140
160
180
200
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=12ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
230 
 
 
Figure B.6 Pushover Curves for Unbraced 3-Pile Bent, H=12ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
20
40
60
80
100
120
140
160
180
200
0 5 10 15 20 25 30 35 40
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=12ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
231 
 
 
Figure B.7 Pushover Curves for Unbraced 3-Pile Bent, H=16ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
20
40
60
80
100
120
140
0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=16ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
232 
 
 
Figure B.8 Pushover Curves for Unbraced 3-Pile Bent, H=16ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
20
40
60
80
100
120
140
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=16ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
233 
 
 
Figure B.9 Pushover Curves for Unbraced 3-Pile Bent, H=16ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
20
40
60
80
100
120
140
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=16ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
234 
 
 
Figure B.10 Pushover Curves for Unbraced 3-Pile Bent, H=8ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
100
200
300
400
500
600
0 2 4 6 8 10 12 14 16 18 20
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=8ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
235 
 
 
Figure B.11 Pushover Curves for Unbraced 3-Pile Bent, H=8ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
400
450
500
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=8ft, P-Load=40kips, Dia=14in
Scour = 0ft 
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
236 
 
 
Figure B.12 Pushover Curves for Unbraced 3-Pile Bent, H=8ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
100
200
300
400
500
600
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=8ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
237 
 
 
Figure B.13 Pushover Curves for Unbraced 3-Pile Bent, H=12ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=12ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
238 
 
 
Figure B.14 Pushover Curves for Unbraced 3-Pile Bent, H=12ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30 35 40
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=12ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
239 
 
 
Figure B.15 Pushover Curves for Unbraced 3-Pile Bent, H=12ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=12ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
240 
 
 
Figure B.16 Pushover Curves for Unbraced 3-Pile Bent, H=16ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0.00 10.00 20.00 30.00 40.00 50.00 60.00
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=16ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
241 
 
 
Figure B.17 Pushover Curves for Unbraced 3-Pile Bent, H=16ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=16ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
242 
 
 
Figure B.18 Pushover Curves for Unbraced 3-Pile Bent, H=16ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 3-Pile Bent, H=16ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
243 
 
 
Figure B.18 Pushover Curves for Unbraced 4-Pile Bent, H=8ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
400
450
0 2 4 6 8 10 12 14 16 18 20
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=8ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
244 
 
 
Figure B.19 Pushover Curves for Unbraced 4-Pile Bent, H=8ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=8ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
245 
 
 
Figure B.21 Pushover Curves for Unbraced 4-Pile Bent, H=8ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
400
450
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=8ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
246 
 
 
Figure B.22 Pushover Curves for Unbraced 4-Pile Bent, H=12ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=12ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
247 
 
 
Figure B.23 Pushover Curves for Unbraced 4-Pile Bent, H=12ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=12ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
248 
 
 
Figure B.24 Pushover Curves for Unbraced 4-Pile Bent, H=12ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=12ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
249 
 
 
Figure B.25 Pushover Curves for Unbraced 4-Pile Bent, H=16ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
20
40
60
80
100
120
140
160
180
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=16ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
250 
 
 
Figure B.26 Pushover Curves for Unbraced 4-Pile Bent, H=16ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
20
40
60
80
100
120
140
160
180
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=16ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
251 
 
 
Figure B.27 Pushover Curves for Unbraced 4-Pile Bent, H=16ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
20
40
60
80
100
120
140
160
180
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=16ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
252 
 
 
Figure B.28 Pushover Curves for Unbraced 4-Pile Bent, H=8ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
100
200
300
400
500
600
700
0 2 4 6 8 10 12 14
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=8ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
253 
 
 
Figure B.29 Pushover Curves for Unbraced 4-Pile Bent, H=8ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
100
200
300
400
500
600
700
0 2 4 6 8 10 12 14
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=8ft, P-Load=40kips, Dia=14in
Scour = 0ft 
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
254 
 
 
Figure B.30 Pushover Curves for Unbraced 4-Pile Bent, H=8ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
100
200
300
400
500
600
700
0 2 4 6 8 10 12 14
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=8ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
255 
 
 
Figure B.31 Pushover Curves for Unbraced 4-Pile Bent, H=12ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
400
450
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=12ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
256 
 
 
Figure B.32 Pushover Curves for Unbraced 4-Pile Bent, H=12ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
400
450
0 5 10 15 20 25
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=12ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
257 
 
 
Figure B.33 Pushover Curves for Unbraced 4-Pile Bent, H=12ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
400
450
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbarced 4-Pile Bent, H=12ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
258 
 
 
Figure B.34 Pushover Curves for Unbraced 4-Pile Bent, H=16ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30 35 40
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=16ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
259 
 
 
Figure B.35 Pushover Curves for Unbraced 4-Pile Bent, H=16ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 5 10 15 20 25 30 35 40
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=16ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
260 
 
 
Figure B.36 Pushover Curves for Unbraced 4-Pile Bent, H=16ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 4-Pile Bent, H=16ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
261 
 
 
Figure B.37 Pushover Curves for Unbraced 5-Pile Bent, H=8ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
100
200
300
400
500
600
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=8ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
262 
 
 
Figure B.38 Pushover Curves for Unbraced 5-Pile Bent, H=8ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=8ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
263 
 
 
Figure B.39 Pushover Curves for Unbraced 5-Pile Bent, H=8ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=8ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
264 
 
 
Figure B.40 Pushover Curves for Unbraced 5-Pile Bent, H=12ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=12ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
265 
 
 
Figure B.41 Pushover Curves for Unbraced 5-Pile Bent, H=12ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=12ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
266 
 
 
Figure B.42 Pushover Curves for Unbraced 5-Pile Bent, H=12ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=12ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
267 
 
 
Figure B.43 Pushover Curves for Unbraced 5-Pile Bent, H=16ft, P=20kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25 30 35 40 45
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=16ft, P-Load=20kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
268 
 
 
Figure B.44 Pushover Curves for Unbraced 5-Pile Bent, H=16ft, P=40kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25 30 35 40
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=16ft, P-Load=40kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
269 
 
 
Figure B.45 Pushover Curves for Unbraced 5-Pile Bent, H=16ft, P=60kips, Diameter=12in, Multiple Levels of Scour 
0
50
100
150
200
250
0 5 10 15 20 25 30 35 40 45
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=16ft, P-Load=60kips, Dia=12in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
270 
 
 
Figure B.46 Pushover Curves for Unbraced 5-Pile Bent, H=8ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
100
200
300
400
500
600
700
800
0 2 4 6 8 10 12 14
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=8ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
271 
 
 
Figure B.47 Pushover Curves for Unbraced 5-Pile Bent, H=8ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
100
200
300
400
500
600
700
800
0 2 4 6 8 10 12 14
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=8ft, P-Load=40kips, Dia=14in
Scour = 0ft 
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
272 
 
 
Figure B.48 Pushover Curves for Unbraced 5-Pile Bent, H=8ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
100
200
300
400
500
600
700
800
0 2 4 6 8 10 12 14
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=8ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
273 
 
 
Figure B.49 Pushover Curves for Unbraced 5-Pile Bent, H=12ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
100
200
300
400
500
600
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=12ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
274 
 
 
Figure B.50 Pushover Curves for Unbraced 5-Pile Bent, H=12ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
100
200
300
400
500
600
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=12ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
275 
 
 
Figure B.51 Pushover Curves for Unbraced 5-Pile Bent, H=12ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
400
450
500
0 5 10 15 20 25 30
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbarced 5-Pile Bent, H=12ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
276 
 
 
Figure B.52 Pushover Curves for Unbraced 5-Pile Bent, H=16ft, P=20kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
400
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=16ft, P-Load=20kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
277 
 
 
Figure B.53 Pushover Curves for Unbraced 5-Pile Bent, H=16ft, P=40kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
400
0 5 10 15 20 25 30 35
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=16ft, P-Load=40kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
278 
 
 
Figure B.54 Pushover Curves for Unbraced 5-Pile Bent, H=16ft, P=60kips, Diameter=14in, Multiple Levels of Scour 
0
50
100
150
200
250
300
350
400
0 5 10 15 20 25 30 35 40
P
usho
v
e
r
 
Lo
a
d 
(
k
i
ps)
Lateral Displacement (in.)
Unbraced 5-Pile Bent, H=16ft, P-Load=60kips, Dia=14in
Scour = 0ft
Scour = 5ft
Scour = 10ft
Scour = 15ft
Scour = 20ft
 
?
?
?
 
 
APPENDIX C 
 
 
 
 
 
 
 
Beam-Column Analyses 
 
 
 
 
 
 
 
279
For?the?following?braced?bent?geometry:??H?=?20?null,?S?=?20?null,?3-Pile?Bent,?Debris?Ranull?Force,?F
t
?=9.72?kips
?
From?the?moment?diagram:
M
F
t
 =?
13
64
9.72kips? 16ft? ?=?31.6?kip ft? ?=?M
Max
M
HB
 =?
3
32
9.72? kips 16? ft?=?14.6?kip ft?
Checking?at?the?locanullon?of?debris?ranull?force?F
t
:
d
F
t
 = 12in 8.5ft 0.12?(?
in
ft
) =?10.98?in
A
F
t
 = 
? 10.98in()
2
?
4
?= 94.7 in
2
S
F
t
 = 
? 10.98in()
3
?
32
 =?130 in
3
Checking?at?horizontal?brace?using?e?ecnullve?secnullon?propernulles:
d
eff
 = 12in 25.83ft 0.12?(?
in
ft
) =?8.90?in I
eff
 = 
? 8.90in()
4
?
64
?= 308 in
4
Also?must?check?P
cr
?for?buckling?in?unbraced?region?exposed?due?to?scour:
P
cr
 = 
2 ?
2
? E? I
eff
?
L
2
 =
2 ?
2
? 1800? ksi 308? in
4
21.5ft 12?()
2
?=?168.3?kips
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
F
t
? ?=12ksi 97.8? in
3
? ?=?97.8?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
F
t
? ?=7ksi 78.3? in
2
? ?=?548.1?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
60 kips?
168.3 kips?
?+??
31.6 kip? ft?
97.8 kip? ft?
?=?0.35?+?0.32?=?0.67?<?0.75???OK!
Note that all braced bents therefore will be safe.
280
For?the?following?unbraced?bent?geometry:??H?=?8?null,?S?=?5?null,?3-Pile?Bent,?F
t
?=9.72?kips
?
Checking?at?the?locanullon?of?e?ecnullve?secnullon,?3.92?null?above?NGL?as?shown?in?figure,?with?a?12in?pile:
d
eff
 = 12in 7.83ft 0.12?(?
in
ft
) = 11.06?in
I
eff
 = 
? 11.06in()
4
?
64
?=?734.5 in
4
A
eff
 = 
? 11.06in()
2
?
4
?=?96.0 in
2
S
eff
 = 
? 11.06in()
3
?
32
 =??132.8 in
3
Determine?P
cr
?for?buckling?:P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 734.5? in
4
11.75ft 12?()
2
?=?164??kips????OK!?for?P?<=??60?kips?in?buckling
Check?at?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 12in 11.75ft 0.12?(?
in
ft
) =?10.59?in I
base
 = 
? 10.59in()
4
?
64
?=?617?in
4
A
base
?=?
? 10.59in()
2
?
4
?=?88.1?in
2
S
base
 = 
? 10.59in()
3
?
32
 =? 116 in
3
?
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 116? in
3
? ?=?116?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 88.1? in
2
? ?=?616.7?kips
Therefore?secnullon?is?controlled?by?buckling,?not?crushing.??Finally,?apply?interacnullon?equanullon.
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
60 kips?
164 kips?
?+??
38.1 kip? ft?
116 kip? ft?
?=?0.37?+?0.33?=?0.70?<?0.75???OK!?for?P?<=?60?kips
Therefore,?all?P-loads?for?a?14in?pile?will?be?adequate?as?well.
281
For?the?following?unbraced?bent?geometry:??H?=?8?null,?S?=?10?null,?3-Pile?Bent,?F
t
?=9.72?kips
?
At?the?locanullon?of?e?ecnullve?secnullon,?5.58?null?above?NGL?as?shown?in?figure,?with?a?12in?pile:
d
eff
 = 12in 11.17ft 0.12?(?
in
ft
) = 10.66?in
I
eff
 = 
? 10.66in()
4
?
64
?=?633.8 in
4
A
eff
 = 
? 10.66in()
2
?
4
?=?89.2 in
2
S
eff
 = 
? 10.66in()
3
?
32
 =??118.9 in
3
Determine?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 633.8? in
4
16.75ft 12?()
2
?=?69.7??kips????OK!?for?P?<=?60?kips?in?buckling
Check?at?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 12in 16.75ft 0.12?(?
in
ft
) =?9.99?in I
base
 = 
? 9.99in()
4
?
64
?=?488?in
4
A
base
?=?
? 9.99in()
2
?
4
?=?78.3?in
2
S
base
 = 
? 9.99in()
3
?
32
 =? 97.8in
3
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 97.8? in
3
? ?=?97.8?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 78.3? in
2
? ?=?548.1?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
282
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
60 kips?
69.7 kips?
?+??
54.3 kip? ft?
97.8 kip? ft?
?=?0.86?+?0.56?=?1.42?>?0.75???No?Good!?for?P?=60
k
Try??P?=?40?kips:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
40 kips?
69.7 kips?
?+??
54.3 kip? ft?
97.8 kip? ft?
?=?0.57?+?0.56?=?1.13?>?0.75???No?Good!?for?P?=40
k
Try?P?=?20?kips:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
20 kips?
69.7 kips?
?+??
54.3 kip? ft?
97.8 kip? ft?
?=?0.29?+?0.56?=?0.85?>?0.75???No?Good!?for?P?=20
k
Checking?again?with?a?14in?pile:
d
eff
 = 14in 11.17ft 0.12?(?
in
ft
) =?12.66?in I
eff
 = 
? 12.66in()
4
?
64
?=1260?in
4
Determine?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 1260? in
4
16.75ft 12?()
2
?=?138.5?kips????OK!?for?P?<=??60?kips?in?buckling
Check?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 14in 16.75ft 0.12?(?
in
ft
) =?11.99?in I
base
 = 
? 11.99in()
4
?
64
?=?1014?in
4
A
base
?=?
? 11.99in()
2
?
4
?=?112.9?in
2
S
base
 = 
? 11.99in()
3
?
32
 =? 169.2in
3
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 169.2? in
3
? ?=?169.2?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 112.9? in
2
? ?=?790.3?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
60 kips?
138.5 kips?
?+??
54.3 kip? ft?
169.2 kip? ft?
?=?0.43?+?0.32?=?0.75????OK!?for?P?<=?60
k
283
For?the?following?unbraced?bent?geometry:??H?=?8?null,?S?=?10?null,?3-Pile?Bent,?F
t
?=6.48?kips
?
At?the?locanullon?of?e?ecnullve?secnullon,?5.58?null?above?NGL?as?shown?in?figure,?with?a?12in?pile:
d
eff
 = 12in 11.17ft 0.12?(?
in
ft
) = 10.66?in
I
eff
 = 
? 10.66in()
4
?
64
?=?633.8 in
4
Determine?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 633.8? in
4
16.75ft 12?()
2
?=?69.7??kips??
Check?at?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 12in 16.75ft 0.12?(?
in
ft
) =?9.99?in I
base
 = 
? 9.99in()
4
?
64
?=?488?in
4
A
base
?=?
? 9.99in()
2
?
4
?=?78.3?in
2
S
base
 = 
? 9.99in()
3
?
32
 =? 97.8in
3
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 97.8? in
3
? ?=?97.8?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 78.3? in
2
? ?=?548.1?kips
Determine?maximum?P?value?where?interacnullon?equanullon?=?0.75:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
P
max
69.7 kips?
?+??
36.2 kip? ft?
97.8 kip? ft?
??=?0.38?+?0.37?=?0.75???P
max
?=?26?kips
284
For?the?following?unbraced?bent?geometry:??H?=?12?null,?S?=?0?null,?3-Pile?Bent,F
t
?=?9.27?kips
?
At?the?locanullon?of?e?ecnullve?secnullon,?3.58?null?above?NGL?as?shown?in?figure,?with?a?12in?pile:
d
eff
 = 12in 7.17ft 0.12?(?
in
ft
) = 11.1?in
I
eff
 = 
? 11.1in()
4
?
64
?=?745.2 in
4
Determine?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 745.2? in
4
10.75ft 12?()
2
?=?198??kips????OK!?for?P?<=?60?kips?in?buckling
Check?at?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 12in 10.75ft 0.12?(?
in
ft
) =?9.74?in I
base
 = 
? 9.74in()
4
?
64
?=?441.7?in
4
A
base
?=?
? 9.74in()
2
?
4
?=?74.5?in
2
S
base
 = 
? 9.74in()
3
?
32
 =? 90.7in
3
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 90.7? in
3
? ?=?90.7?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 74.5? in
2
? ?=?521.5?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
60 kips?
198 kips?
?+??
34.8 kip? ft?
90.7 kip? ft?
?=?0.31?+?0.38?=?0.69?<??0.75??OK!?for?P?<=?60?kips
Therefore,?14in?diameter?pile?will?also?be?safe?for?all?P-loads.
285
For?the?following?unbraced?bent?geometry:??H?=?12?null,?S?=?5?null,?3-Pile?Bent,??F
t
?=?9.27?kips
?
At?the?locanullon?of?e?ecnullve?secnullon,?5.25?null?above?NGL?as?shown?in?figure,?with?a?12in?pile:
d
eff
 = 12in 10.50ft 0.12?(?
in
ft
) = 10.74?in
I
eff
 = 
? 10.74in()
4
?
64
?=?653.1 in
4
A
eff
 = 
? 10.74in()
2
?
4
??=?90.6 in
2
S
eff
 = 
? 10.74in()
3
?
32
 =?121.6 in
3
Determine?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 653.1? in
4
15.75ft 12?()
2
?=?81.2??kips????OK!?for?P?<=??60?kips?in?buckling
Check?at?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 12in 15.75ft 0.12?(?
in
ft
) =?10.1?in I
base
 = 
? 10.1in()
4
?
64
?=?510.8?in
4
A
base
?=?
? 10.1in()
2
?
4
?=?80.1?in
2
S
base
 = 
? 10.1in()
3
?
32
 =? 101.1in
3
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 101.1? in
3
? ?=?101.1?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 80.1? in
2
? ?=?560.7?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
286
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
60 kips?
81.2 kips?
?+??
51.0 kip? ft?
101.3 kip? ft?
?=?0.74?+?0.50?=?1.24?>?0.75???NG!?for?P?=?60?kips
Try??P?=?40?kips:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
40 kips?
81.2 kips?
?+??
51.0 kip? ft?
101.3 kip? ft?
?=?0.49?+?0.50?=?0.99?>?0.75???NG!?for?P?=?40?kips
Try?P?=?20?kips:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
20 kips?
81.2 kips?
?+??
51.0 kip? ft?
101.3 kip? ft?
?=?0.25?+?0.50?=?0.75??OK!?for?P?=?20?kips
Check?P?=?40,?60?kips?for?14in?diameter?pile.?(20?kips?P-load?will?be?okay?by?inspecnullon.)
At?the?locanullon?of?e?ecnullve?secnullon,?5.25?null?above?NGL?as?shown?in?figure,?with?a?14in?pile:
d
eff
 = 14in 10.50ft 0.12?(?
in
ft
) = 12.74?in
I
eff
 = 
? 12.74in()
4
?
64
?=?1293 in
4
Determine?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 1293? in
4
15.75ft 12?()
2
?=160.7??kips???OK!?for?P?<=?60?kips?in?buckling
Check?at?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 14in 15.75ft 0.12?(?
in
ft
) =?12.1?in I
base
 = 
? 12.1in()
4
?
64
?=?1052?in
4
A
base
?=?
? 12.1in()
2
?
4
?=?114?in
2
S
base
 = 
? 12.1in()
3
?
32
 =? 173in
3
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 173? in
3
? ?=?173?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 114? in
2
? ?=?798?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
60 kips?
160.7 kips?
?+??
51.0 kip? ft?
173 kip? ft?
?=?0.37?+?0.29?=?0.66?<?0.75???OK!?for?P?<=??60?kips
287
For?the?following?unbraced?bent?geometry:??H?=?12?null,?S?=?5?null,?3-Pile?Bent,?F
t
?=?6.48?kips
At?the?locanullon?of?e?ecnullve?secnullon,?5.25?null?above?NGL?as?shown?in?figure,?with?a?12in?pile:
d
eff
 = 12in 10.50ft 0.12?(?
in
ft
) = 10.74?in
I
eff
 = 
? 10.74in()
4
?
64
?=?653.1 in
4
A
eff
 = 
? 10.74in()
2
?
4
??=?90.6 in
2
S
eff
 = 
? 10.74in()
3
?
32
 =?121.6 in
3
Recall?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 653.1? in
4
15.75ft 12?()
2
?=?81.2??kips
Check?at?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 12in 15.75ft 0.12?(?
in
ft
) =?10.1?in I
base
 = 
? 10.1in()
4
?
64
?=?510.8?in
4
A
base
?=?
? 10.1in()
2
?
4
?=?80.1?in
2
S
base
 = 
? 10.1in()
3
?
32
 =? 101.1in
3
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 101.1? in
3
? ?=?101.1?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 80.1? in
2
? ?=?560.7?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
P
max
81.2 kips?
?+??
35.6 kip? ft?
101.3 kip? ft?
?=?0.40?+?0.35?=?0.75???P
max
?=?32?kips
288
For?the?following?unbraced?bent?geometry:??H?=?12?null,?S?=?10?null,?3-Pile?Bent,?F
t
?=?9.27?kips
?
At?the?locanullon?of?e?ecnullve?secnullon,?6.92?null?above?NGL?as?shown?in?figure,?with?a?12in?pile:
d
eff
 = 12in 13.83ft 0.12?(?
in
ft
)?=?10.3?in
I
eff
 = 
? 10.3in()
4
?
64
?=?552.5 in
4
Determine?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 552.5? in
4
20.75ft 12?()
2
?=?39.6??kips???No?Good!?for?P?=?40,?60?kips
Do?not?need?to?check?rupture?or?interanullon?equanullon?since?fails?in?buckling.
Check?P?=?20?kips?for?12in?diameter?pile?(40?kip?load?will?be?inadequate?in?buckling?alone):
d
base
 = 12in 20.75ft 0.12?(?
in
ft
) =?9.51?in I
base
 = 
? 9.51in()
4
?
64
?=?104.5?in
4
A
base
?=?
? 9.51in()
2
?
4
?=?71.03?in
2
S
base
 = 
? 9.51in()
3
?
32
 =?84.4in
3
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 84.4? in
3
? ?=?84.4?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 71.03? in
2
? ?=?497.2?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
20 kips?
39.6 kips?
?+?
45.4 kip? ft?
84.4 kip? ft?
?=?0.51?+?0.54?=?1.05?>?0.75???No?Good!
for P = 20 kips
289
Determine?maximum?value?of?P?for?interacnullon?equanullon?=?0.75:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
P
max
39.6 kips?
?+?
45.4 kip? ft?
84.4 kip? ft?
?=?0.21?+?0.54?=??0.75???P
max
?=?8.3?kips
Checking?again?while?assuming?a?14in?pile?instead:
d
eff
 = 14in 17.17ft 0.12?(?
in
ft
) =?12.34?in I
eff
 = 
? 12.34in()
4
?
64
?=?1138?in
4
S
eff
 = 
? 12.34in()
3
?
32
 =? 184.5in
3
A
eff
?=?
? 12.34in()
2
?
4
?=?119.6?in
2
Determine?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 1138? in
4
20.75ft 12?()
2
?=?81.6?kips????OK!?for?all?P-loads?in?buckling
Check?at?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 14in 20.75ft 0.12?(?
in
ft
) =?11.51?in I
base
 = 
? 11.51in()
4
?
64
?=?861.5?in
4
A
base
?=?
? 11.51in()
2
?
4
?=?104?in
2
S
base
 = 
? 11.51in()
3
?
32
 =? 149.7in
3
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 149.7? in
3
? ?=?149.7?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 104? in
2
? ?=?728?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
Finally,?by?applying?the?interacnullon?equanullon?to?determine?maximum?load:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
P
max
81.6 kips?
?+??
45.4 kip? ft?
149.7 kip? ft?
?=?0.45?+?0.30?=??0.75???P
max
?=?36?kips
290
For?the?following?unbraced?bent?geometry:??H?=?12?null,?S?=?10?null,?3-Pile?Bent,?F
t
?=?6.48?kips
?
Check?P?=?20?kips?for?12in?diameter?pile?for?smaller?ranull:
Recall,
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 552.5? in
4
20.75ft 12?()
2
?=?39.6??kips?
d
base
 = 12in 20.75ft 0.12?(?
in
ft
) =?9.51?in I
base
 = 
? 9.51in()
4
?
64
?=?104.5?in
4
A
base
?=?
? 9.51in()
2
?
4
?=?71.03?in
2
S
base
 = 
? 9.51in()
3
?
32
 =?84.4in
3
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 84.4? in
3
? ?=?84.4?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 71.03? in
2
? ?=?497.2?kips
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
20 kips?
39.6 kips?
?+??
30.3 kip? ft?
84.4 kip? ft?
?=?0.51?+?0.36?=?0.87?>?0.75???NG!?for?P?=?20?kips
Only?need?to?check?P?=?40,?60?kips?for?the?smaller?ranull?for?14in?diameter?piles.??Recall,?
A
eff
?=?
? 12.34in()
2
?
4
?=?119.6?in
2
291
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 1138? in
4
20.75ft 12?()
2
?=?81.6?kips??
Check?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 14in 20.75ft 0.12?(?
in
ft
) =?11.51?in I
base
 = 
? 11.51in()
4
?
64
?=?861.5?in
4
A
base
?=?
? 11.51in()
2
?
4
?=?104?in
2
S
base
 = 
? 11.51in()
3
?
32
 =? 149.7in
3
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 149.7? in
3
? ?=?149.7?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 104? in
2
? ?=?728?kips
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
60 kips?
81.6 kips?
?+??
30.3 kip? ft?
149.7 kip? ft?
?=?0.74?+?0.20?=?0.94?>?0.75???NG!?for?P?=?60?kips
Try??P?=?40?kips:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
40 kips?
81.6 kips?
?+??
30.3 kip? ft?
149.7 kip? ft?
?=?0.49?+?0.20?=?0.69?<?0.75???OK!?for?P?=?40?kips
Determine?maximum?value?of?P:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
P
max
81.6 kips?
?+??
30.3 kip? ft?
149.7 kip? ft?
?=?0.55??+?0.20??=?0.75??P
max
?=?44?kips
292
For?the?following?unbraced?bent?geometry:??H?=?12?null,?S?=?15?null,?3-Pile?Bent,??F
t
?=?9.27?kips
?
At?the?locanullon?of?e?ecnullve?secnullon,?8.58?null?above?NGL?as?shown?in?figure,?with?a?12in?pile:
d
eff
 = 12in 17.17ft 0.12?(?
in
ft
) = 9.94?in
I
eff
 = 
? 8.90in()
4
?
64
?= 479.2 in
4
Determine?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 479.2? in
4
25.75ft 12?()
2
?=?22.3??kips????No?Good!?for?P?<=??60?kips
By?inspecnullon,?it?will?fail?for?all?P-load?levels?(including?P?=?20?kips?anuller?e?ects?of?interacnullon).
Checking?again?while?assuming?a?14in?pile?instead:
d
eff
 = 14in 17.17ft 0.12?(?
in
ft
) =?11.84?in I
eff
 = 
? 11.84in()
4
?
64
?=?964.7?in
4
Determine?P
cr
?for?buckling?:
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 964? in
4
25.75ft 12?()
2
?=?44.8?kips????No?Good!?for?P?=?40,?60?kips
Check?at?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 14in 25.75ft 0.12?(?
in
ft
) =?10.91?in I
base
 = 
? 10.91in()
4
?
64
?=?695.4?in
4
A
base
?=?
? 10.91in()
2
?
4
?=?93.5?in
2
S
base
 = 
? 10.91in()
3
?
32
 =? 127.9in
3
293
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 127.9? in
3
? ?=?127.9?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 93.5? in
2
? ?=?654.5?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
20 kips?
44.8 kips?
?+??
61.6 kip? ft?
127.9 kip? ft?
?=?0.45?+?0.48?=?0.93?>?0.75???NG!?for?P?=?20?kips
294
For?the?following?unbraced?bent?geometry:??H?=?12?null,?S?=?15?null,?3-Pile?Bent,F
t
?=6.48?kips
?
Only?P?=?20?kips?needs?to?be?checked?for?the?smaller?ranull?for?14in?diameter?pile?since?others?P-loads?fail?in
buckling?alone.??
Recall,
A
eff
?=?
? 11.84in()
2
?
4
?=?110.1?in
2
P
cr
 = 
0.25 ?
2
? E? I
eff
?
L
2
 =
0.25 ?
2
? 1800? ksi 964? in
4
25.75ft 12?()
2
?=?44.8?kips?
Check?at?interacnullon?equanullon?at?base?(smallest?secnullon,?therefore?most?crinullcal):
d
base
 = 14in 25.75ft 0.12?(?
in
ft
) =?10.91?in I
base
 = 
? 10.91in()
4
?
64
?=?695.4?in
4
A
base
?=?
? 10.91in()
2
?
4
?=?93.5?in
2
S
base
 = 
? 10.91in()
3
?
32
 =? 127.9in
3
Recall,
??
rupture
?=?12.0?ksi? ???M
rupture
?=??
rupture
S
base
? ?=12ksi 127.9? in
3
? ?=?127.9?kip-null
??
crushing
?=?7.0??ksi ???P
crushing
?=??
crushing
A
base
? ?=7ksi 93.5? in
2
? ?=?654.5?kips
Therefore?secnullon?is?controlled?by?buckling,?rather?than?crushing.
Finally,?by?applying?the?interacnullon?equanullon:
?
P
axial
P
cr
?+?
M
Max
M
rupture
??=?
20 kips?
44.8 kips?
?+??
41.07 kip? ft?
127.9 kip? ft?
?=?0.45?+?0.32?=?0.77?>?0.75???NG!?for?P?=?20?kips
295
	
	
	
	
	
 
 
APPENDIX D 
 
 
 
 
 
 
 
Automated Screening Tool 
Visual Basic Code 
 
 
 
 
 
 
 
296
 
 
 
Appendix D.1 Preliminary Evaluation and Related Modules 
Public Class Intro 
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Button1.Click 
        'Show next form 
        My.Forms.PreliminaryEval.Show() 
        WindowState = FormWindowState.Minimized 
 
    End Sub 
 
    Private Sub HelpToolStripButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles HelpToolStripButton.Click 
        My.Forms.GeneralHelpFile.ShowDialog() 
    End Sub 
End Class 
 
Public Class GeneralHelpFile 
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Button1.Click 
        Me.DialogResult = DialogResult.OK 
    End Sub 
End Class 
 
Public Class PreliminaryEval 
 
    Private Sub PreliminaryEval_Load(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Load 
 
        'Following code lines are for placing options in dropdown boxes 
        'Number of Piles drop-down box 
        ComboBoxNoOfPiles.Items.Add("3") 
        ComboBoxNoOfPiles.Items.Add("4") 
        ComboBoxNoOfPiles.Items.Add("5") 
        ComboBoxNoOfPiles.Items.Add("More than 5 piles") 
 
        'PileDiameter drop-down box 
        ComboBoxPileDiameter.Items.Add("12 in") 
        ComboBoxPileDiameter.Items.Add("14 in") 
 
        'Adds options to the X-Bracing combo box 
        ComboBoxBracingScheme.Items.Add("Non-Braced") 
        ComboBoxBracingScheme.Items.Add("X-Braced") 
 
    End Sub 
 
 
297
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Button2.Click 
        'Exit routine 
        End 
    End Sub 
 
    Private Sub RadioButton2_CheckedChanged(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles RadioButton2.CheckedChanged 
        'Checks if ST is applicable 
        If RadioButton2.Checked = True Then 
            MsgBox("Bent is safe from scour! Please exit the Screening Tool.") 
        End If 
    End Sub 
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Button1.Click 
        'Recieves input from user for future calculations 
        Lbg = Val(txtLbg.Text) 
        Smax = Val(txtScr.Text) 
        BentHeight = Val(txtBentHeight.Text) 
        Span = Val(SpanText.Text) 
        WaterDepth = Val(WaterDepthText.Text) 
 
        'Fill variable associated with combo boxes 
        'Diameter 
        Select Case ComboBoxPileDiameter.SelectedIndex 
            Case 0 '12in 
                Dia = 12 'inches 
            Case 1 
                Dia = 14 'inches 
        End Select 
 
        'Number of Piles 
        Select Case ComboBoxNoOfPiles.SelectedIndex 
            Case 0 
                NoPiles = 3 
            Case 1 
                NoPiles = 4 
            Case 2 
                NoPiles = 5 
            Case 3 
                NoPiles = 0 
        End Select 
 
        'Bracing Scheme 
        Select Case ComboBoxBracingScheme.SelectedIndex 
            Case 0 
                Bracing = "Non-braced" 
            Case 1 
                Bracing = "X-braced" 
        End Select 
        If RadioButton4.Checked = True Then 
            DebrisRaft = "Yes" 
        Else 
            DebrisRaft = "No" 
        End If 
 
        'Check applicability of ST 
298
        If NoPiles = 0 Then 
            MsgBox("Screening Tool cannot check adequacy of this bent.  Please exit the 
Screening Tool.") 
        Else 
            If RadioButton6.Checked = True Then 'Marine borer rot is an issue 
                MsgBox("Corrective action should be taken to build pile section to 
original or greater diameter.") 
                'Calculate new length of pile embedment 
                Las = Lbg - Smax 
 
                'Check Kick-out Failure 
                If Smax >= Lbg Then 
                    MsgBox("Bent will have kick-out failure!  Take corrective action 
immediately!") 
                End If 
 
                'Continuation message 
                PictureBox1.Visible = True 
                Label1.Visible = True 
                PictureBox2.Visible = False 
 
            Else 
                'Calculate new length of pile embedment 
                Las = Lbg - Smax 
 
                'Check Kick-out Failure 
                If Smax >= Lbg Then 
                    MsgBox("Bent will have kick-out failure!  Take corrective action 
immediately!") 
                End If 
 
                'Continuation message 
                PictureBox1.Visible = True 
                Label1.Visible = True 
                PictureBox2.Visible = False 
 
            End If 
        End If 
    End Sub 
 
    'Displays Help File 
    Private Sub HelpToolStripButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles HelpToolStripButton.Click 
        My.Forms.PrelimHelpFile.ShowDialog() 
 
    End Sub 
 
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Button3.Click 
 
        'Show next form 
        My.Forms.PMaxEvalForm.Show() 
        WindowState = FormWindowState.Minimized 
 
    End Sub 
 
    Private Sub RadioButton7_CheckedChanged(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles RadioButton7.CheckedChanged 
299
        'Checks if ST is applicable 
        If RadioButton7.Checked = True Then 
            MsgBox("Screening Tool is meant for the evaluation of timber pile bents.  
Please Exit.") 
        End If 
    End Sub 
 
End Class 
Public Class PrelimHelpFile 
 
    'Closes Help File Dialog Box 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Button1.Click 
        Me.DialogResult = DialogResult.OK 
    End Sub 
 
End Class 
 
 
 
 
 
300
 
 
 
Appendix D.2 Input Variables Module 
Module InputVariables 
 
    'Define Limit State Safety Check as True/False for easier output in report (False 
being UNSAFE) 
    Public Plunging, KickOut, Buckling, Pushover, BeamColumn As String 
 
    'Define Public variables for use in other forms 
    Public Lbg, Las, Smax, BentHeight, Dia, Span, WaterDepth, PLoad As Single 
    Public NoPiles As Integer 
    Public DebrisRaft, Bracing As String 
 
    'Define Public variables for Pmax Eval 
    Public PileAppliedMax, BentAppliedMax As Single 
 
    'Define Public variables for Plunging Eval 
    Public vBentNo1, vHammerEnergy1, vDrivingResistance1, vLas1, vFrictionCapacity1, 
vFrictionCritScour1, vFrictionSafety1, vEndBear1, vBearCritScour1, vBearingSafety1 As 
String 
    Public vBentNo2, vHammerEnergy2, vDrivingResistance2, vLas2, vFrictionCapacity2, 
vFrictionCritScour2, vFrictionSafety2, vEndBear2, vBearCritScour2, vBearingSafety2 As 
String 
    Public vBentNo3, vHammerEnergy3, vDrivingResistance3, vLas3, vFrictionCapacity3, 
vFrictionCritScour3, vFrictionSafety3, vEndBear3, vBearCritScour3, vBearingSafety3 As 
String 
    Public vBentNo4, vHammerEnergy4, vDrivingResistance4, vLas4, vFrictionCapacity4, 
vFrictionCritScour4, vFrictionSafety4, vEndBear4, vBearCritScour4, vBearingSafety4 As 
String 
    Public vBentNo5, vHammerEnergy5, vDrivingResistance5, vLas5, vFrictionCapacity5, 
vFrictionCritScour5, vFrictionSafety5, vEndBear5, vBearCritScour5, vBearingSafety5 As 
String 
    Public PMaxPlunge, DrivingResistance, DrivingEnergy, EndBearingCapacity, 
FrictionCapacity, HammerEnergy, Efficiency As Single 
    Public ScrEndBearing, ScrFriction As Single 
    Public HammerType, PileType As String 
    Public BentNo As Integer 
    Public BearingSafe, FrictionSafe As String 
 
    'Define Public variables for Buckling Eval 
    Public DiaEff, DiaEffBelowBrace, IEff, IEffBelowBrace, Lag, LagBelowBrace, ModulusE 
As Single 
    Public C1, C2, C3 As Single 
    Public Pi As Double 
 
    'Define Public variables for Pushover Eval 
    Public RaftForce, PloadMax, PushoverScour, PushoverHeight As Single 
 
    'Define Public variables for BeamColumn Eval 
    Public CritScourBeamCol As String 
301
 
    'Define Public variables for Printing form 
    Public Engineer, CheckDate, BIN, City, County, Notes As String 
    Public IEffTextVal, LcrTextVal, ScourCritTextVal As Single 
    Public FailureModeTextVal, PushoverCritScourTextVal As String 
       
End Module 
302
 
 
 
Appendix D.3 Pile And Bent Applied Load Evaluation and Related Modules 
Public Class PMaxEvalForm 
 
    Private Sub EnterButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles EnterButton.Click 
        PileAppliedMax = Val(PApplKnownText.Text) 
        BentAppliedMax = Val(BentApplKnownText.Text) 
 
        PLoad = PileAppliedMax 
 
        EnterArrow.Visible = False 
        ContinueArrow.Visible = True 
        Label1.Visible = True 
 
    End Sub 
 
    Private Sub ContinueButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ContinueButton.Click 
        'Show next form 
        My.Forms.PlungingEval.Show() 
        WindowState = FormWindowState.Minimized 
    End Sub 
 
    Private Sub ExitButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ExitButton.Click 
        'Exit routine 
        End 
    End Sub 
 
    Private Sub HelpToolStripButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles HelpToolStripButton.Click 
        My.Forms.PileAppliedLoadHelp.ShowDialog() 
    End Sub 
End Class 
 
Public Class PileAppliedLoadHelp 
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Button1.Click 
        Me.DialogResult = DialogResult.OK 
    End Sub 
End Class 
 
 
303
 
 
 
Appendix D.4 Plunging and Kick-out Evaluation and Related Modules 
Public Class PlungingEval 
 
    Public Las1, Las2, Las3, Las4, Las5, Las6 As Single 
 
    Private Sub ExitButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ExitButton.Click 
        'Exit routine 
        End 
    End Sub 
 
    Private Sub PlungingEval_Load(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Load 
        'Following code lines are for placing options in dropdown boxes 
        'Hammer Type drop-down box 
        HammerTypeCombo.Items.Add("Single Acting Air/Steam (Assumed 67% Efficient)") 
        HammerTypeCombo.Items.Add("Double Acting Air/Steam (Assumed 50% Efficient)") 
        HammerTypeCombo.Items.Add("Diesel (Assumed 80% Efficient)") 
        HammerTypeCombo.Items.Add("Drop Hammer (Assumed 50% Efficient)") 
 
    End Sub 
 
    Private Sub EnterButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles EnterButton.Click 
        'Recieve input data and put to variables 
        HammerType = HammerTypeCombo.SelectedItem 
        'Convert Pile Load to tons and show in form for comparison purposes 
        PMaxPlunge = PileAppliedMax / 2 'tons 
        PMaxApplied.Text = PMaxPlunge.ToString("###0.00") 
 
        'Run plunging evaluation for each column of input data 
        If Val(BentNo1.Text) <> 0 Then 
            'Gather input from user 
            Lbg = Val(Lbg1.Text) 'ft 
            Smax = Val(Scour1.Text) 'ft 
            DrivingResistance = Val(DrivingResist1.Text) 'bpi 
            HammerEnergy = Val(HammerEnergy1.Text) 'ft-lbs 
            If HammerType = "Single Acting Air/Steam (Assumed 67% Efficient)" Then 
                HammerEnergy = 0.67 * HammerEnergy 
                Efficiency = "67" 
            ElseIf HammerType = "Double Acting Air/Steam (Assumed 50% Efficient)" Then 
                HammerEnergy = 0.5 * HammerEnergy 
                Efficiency = "50" 
            ElseIf HammerType = "Diesel (Assumed 80% Efficient)" Then 
                HammerEnergy = 0.8 * HammerEnergy 
                Efficiency = "80" 
            Else 
                HammerEnergy = 0.5 * HammerEnergy 
                Efficiency = "50" 
304
            End If 
 
            'Send input to Plunging Functions module 
            ScrEndBearing = CritScourPlunging_EndBearing(HammerEnergy, DrivingResistance, 
PMaxPlunge, Lbg) 
            EndBearingCapacity = EndBearingCapacityEval(HammerEnergy, DrivingResistance, 
Smax, Lbg) 
            ScrFriction = CritScourPlunging_Friction(HammerEnergy, DrivingResistance, 
PMaxPlunge, Lbg) 
            FrictionCapacity = FrictionCapacityEval(HammerEnergy, DrivingResistance, 
Smax, Lbg) 
 
            'Output results back to form 
            EndBear1.Text = EndBearingCapacity.ToString("###0.00") 
            BearCritScour1.Text = ScrEndBearing.ToString("###0.00") 
            FrictionCapacity1.Text = FrictionCapacity.ToString("###0.00") 
            FrictionCritScour1.Text = ScrFriction.ToString("###0.00") 
 
            'Format for safe/unsafe checks 
            'End bearing failure checks 
            If ScrEndBearing < 0 Then 
                MsgBox("Projected critical scour value is negative, therefore maximum 
applied load is greater than pile capacity.") 
                BearingSafety1.ForeColor = Color.Red 
                BearingSafety1.Text = "UNSAFE" 
            End If 
 
            If ScrEndBearing >= Smax Then 
                BearingSafety1.ForeColor = Color.Blue 
                BearingSafety1.Text = "SAFE" 
            Else 
                BearingSafety1.ForeColor = Color.Red 
                BearingSafety1.Text = "UNSAFE" 
            End If 
 
            'Friction failure checks 
            If ScrFriction < 0 Then 
                MsgBox("Projected critical scour value is negative, therefore maximum 
applied load is greater than pile capacity.") 
                FrictionSafety1.ForeColor = Color.Red 
                FrictionSafety1.Text = "UNSAFE" 
            End If 
 
            If ScrFriction >= Smax Then 
                FrictionSafety1.ForeColor = Color.Blue 
                FrictionSafety1.Text = "SAFE" 
            Else 
                FrictionSafety1.ForeColor = Color.Red 
                FrictionSafety1.Text = "UNSAFE" 
            End If 
 
            'Kickout failure check (input recieved, checked later) 
            Las1 = Val(Lbg1.Text) - Val(Scour1.Text) 'ft 
            If Las1 < 2.5 Then 
                MsgBox("Pile in Column 1 unsafe for kick-out.  Take preventative measures 
such as riprap.") 
            ElseIf 2.5 <= Las1 And Las1 < 5 Then 
305
                MsgBox("Pile in Column 1 in danger of being unsafe for kick-out after 
future scour events.  Take preventative measures such as riprap.") 
            Else 
            End If 
 
        End If 
 
        'Repeat for Bent 2 Column 
        If Val(BentNo2.Text) <> 0 Then 
            'Gather input from user 
            Lbg = Val(Lbg2.Text) 'ft 
            Smax = Val(Scour2.Text) 'ft 
            DrivingResistance = Val(DrivingResist2.Text) 'bpi 
            HammerEnergy = Val(HammerEnergy2.Text) 'ft-lbs 
            If HammerType = "Single Acting Air/Steam (Assumed 67% Efficient)" Then 
                HammerEnergy = 0.67 * HammerEnergy 
            ElseIf HammerType = "Double Acting Air/Steam (Assumed 50% Efficient)" Then 
                HammerEnergy = 0.5 * HammerEnergy 
            ElseIf HammerType = "Diesel (Assumed 80% Efficient)" Then 
                HammerEnergy = 0.8 * HammerEnergy 
            Else 
                HammerEnergy = 0.5 * HammerEnergy 
            End If 
 
            'Send input to Plunging Functions module 
            ScrEndBearing = CritScourPlunging_EndBearing(HammerEnergy, DrivingResistance, 
PMaxPlunge, Lbg) 
            EndBearingCapacity = EndBearingCapacityEval(HammerEnergy, DrivingResistance, 
Smax, Lbg) 
            ScrFriction = CritScourPlunging_Friction(HammerEnergy, DrivingResistance, 
PMaxPlunge, Lbg) 
            FrictionCapacity = FrictionCapacityEval(HammerEnergy, DrivingResistance, 
Smax, Lbg) 
 
            'Output results back to form 
            EndBear2.Text = EndBearingCapacity.ToString("###0.00") 
            BearCritScour2.Text = ScrEndBearing.ToString("###0.00") 
            FrictionCapacity2.Text = FrictionCapacity.ToString("###0.00") 
            FrictionCritScour2.Text = ScrFriction.ToString("###0.00") 
 
            'Format for safe/unsafe checks 
            'End bearing failure checks 
            If ScrEndBearing < 0 Then 
                MsgBox("Projected critical scour value is negative, therefore maximum 
applied load is greater than pile capacity.") 
                BearingSafety2.ForeColor = Color.Red 
                BearingSafety2.Text = "UNSAFE" 
            End If 
 
            If ScrEndBearing >= Smax Then 
                BearingSafety2.ForeColor = Color.Blue 
                BearingSafety2.Text = "SAFE" 
            Else 
                BearingSafety2.ForeColor = Color.Red 
                BearingSafety2.Text = "UNSAFE" 
            End If 
 
            'Friction failure checks 
306
            If ScrFriction < 0 Then 
                MsgBox("Projected critical scour value is negative, therefore maximum 
applied load is greater than pile capacity.") 
                FrictionSafety2.ForeColor = Color.Red 
                FrictionSafety2.Text = "UNSAFE" 
            End If 
 
            If ScrFriction >= Smax Then 
                FrictionSafety2.ForeColor = Color.Blue 
                FrictionSafety2.Text = "SAFE" 
            Else 
                FrictionSafety2.ForeColor = Color.Red 
                FrictionSafety2.Text = "UNSAFE" 
            End If 
 
            'Kickout failure check (input recieved, checked later) 
            Las2 = Val(Lbg2.Text) - Val(Scour2.Text) 
            If Las2 < 2.5 Then 
                MsgBox("Pile in Column 2 unsafe for kick-out.  Take preventative measures 
such as riprap.") 
            ElseIf 2.5 <= Las2 And Las2 < 5 Then 
                MsgBox("Pile in Column 2 in danger of being unsafe for kick-out after 
future scour events.  Take preventative measures such as riprap.") 
            Else 
            End If 
 
        End If 
 
        'Repeat for Bent 3 column 
        If Val(BentNo3.Text) <> 0 Then 
            'Gather input from user 
            Lbg = Val(Lbg3.Text) 'ft 
            Smax = Val(Scour3.Text) 'ft 
            DrivingResistance = Val(DrivingResist3.Text) 'bpi 
            HammerEnergy = Val(HammerEnergy3.Text) 'ft-lbs 
            If HammerType = "Single Acting Air/Steam (Assumed 67% Efficient)" Then 
                HammerEnergy = 0.67 * HammerEnergy 
            ElseIf HammerType = "Double Acting Air/Steam (Assumed 50% Efficient)" Then 
                HammerEnergy = 0.5 * HammerEnergy 
            ElseIf HammerType = "Diesel (Assumed 80% Efficient)" Then 
                HammerEnergy = 0.8 * HammerEnergy 
            Else 
                HammerEnergy = 0.5 * HammerEnergy 
            End If 
 
            'Send input to Plunging Functions module 
            ScrEndBearing = CritScourPlunging_EndBearing(HammerEnergy, DrivingResistance, 
PMaxPlunge, Lbg) 
            EndBearingCapacity = EndBearingCapacityEval(HammerEnergy, DrivingResistance, 
Smax, Lbg) 
            ScrFriction = CritScourPlunging_Friction(HammerEnergy, DrivingResistance, 
PMaxPlunge, Lbg) 
            FrictionCapacity = FrictionCapacityEval(HammerEnergy, DrivingResistance, 
Smax, Lbg) 
 
            'Output results back to form 
            EndBear3.Text = EndBearingCapacity.ToString("###0.00") 
            BearCritScour3.Text = ScrEndBearing.ToString("###0.00") 
307
            FrictionCapacity3.Text = FrictionCapacity.ToString("###0.00") 
            FrictionCritScour3.Text = ScrFriction.ToString("###0.00") 
 
            'Format for safe/unsafe checks 
            'End bearing failure checks 
            If ScrEndBearing < 0 Then 
                MsgBox("Projected critical scour value is negative, therefore maximum 
applied load is greater than pile capacity.") 
                BearingSafety3.ForeColor = Color.Red 
                BearingSafety3.Text = "UNSAFE" 
            End If 
 
            If ScrEndBearing >= Smax Then 
                BearingSafety3.ForeColor = Color.Blue 
                BearingSafety3.Text = "SAFE" 
            Else 
                BearingSafety3.ForeColor = Color.Red 
                BearingSafety3.Text = "UNSAFE" 
            End If 
 
            'Friction failure checks 
            If ScrFriction < 0 Then 
                MsgBox("Projected critical scour value is negative, therefore maximum 
applied load is greater than pile capacity.") 
                FrictionSafety3.ForeColor = Color.Red 
                FrictionSafety3.Text = "UNSAFE" 
            End If 
 
            If ScrFriction >= Smax Then 
                FrictionSafety3.ForeColor = Color.Blue 
                FrictionSafety3.Text = "SAFE" 
            Else 
                FrictionSafety3.ForeColor = Color.Red 
                FrictionSafety3.Text = "UNSAFE" 
            End If 
 
            'Kickout failure check (input recieved, checked later) 
            Las3 = Val(Lbg3.Text) - Val(Scour3.Text) 
            If Las3 < 2.5 Then 
                MsgBox("Pile in Column 3 unsafe for kick-out.  Take preventative measures 
such as riprap.") 
            ElseIf 2.5 <= Las3 And Las3 < 5 Then 
                MsgBox("Pile in Column 3 in danger of being unsafe for kick-out after 
future scour events.  Take preventative measures such as riprap.") 
            Else 
            End If 
 
        End If 
 
        'Repeat for Bent Column 4 
        If Val(BentNo4.Text) <> 0 Then 
            'Gather input from user 
            Lbg = Val(Lbg4.Text) 'ft 
            Smax = Val(Scour4.Text) 'ft 
            DrivingResistance = Val(DrivingResist4.Text) 'bpi 
            HammerEnergy = Val(HammerEnergy4.Text) 'ft-lbs 
            If HammerType = "Single Acting Air/Steam (Assumed 67% Efficient)" Then 
                HammerEnergy = 0.67 * HammerEnergy 
308
            ElseIf HammerType = "Double Acting Air/Steam (Assumed 50% Efficient)" Then 
                HammerEnergy = 0.5 * HammerEnergy 
            ElseIf HammerType = "Diesel (Assumed 80% Efficient)" Then 
                HammerEnergy = 0.8 * HammerEnergy 
            Else 
                HammerEnergy = 0.5 * HammerEnergy 
            End If 
 
            'Send input to Plunging Functions module 
            ScrEndBearing = CritScourPlunging_EndBearing(HammerEnergy, DrivingResistance, 
PMaxPlunge, Lbg) 
            EndBearingCapacity = EndBearingCapacityEval(HammerEnergy, DrivingResistance, 
Smax, Lbg) 
            ScrFriction = CritScourPlunging_Friction(HammerEnergy, DrivingResistance, 
PMaxPlunge, Lbg) 
            FrictionCapacity = FrictionCapacityEval(HammerEnergy, DrivingResistance, 
Smax, Lbg) 
 
            'Output results back to form 
            EndBear4.Text = EndBearingCapacity.ToString("###0.00") 
            BearCritScour4.Text = ScrEndBearing.ToString("###0.00") 
            FrictionCapacity4.Text = FrictionCapacity.ToString("###0.00") 
            FrictionCritScour4.Text = ScrFriction.ToString("###0.00") 
 
            'Format for safe/unsafe checks 
            'End bearing failure checks 
            If ScrEndBearing < 0 Then 
                MsgBox("Projected critical scour value is negative, therefore maximum 
applied load is greater than pile capacity.") 
                BearingSafety4.ForeColor = Color.Red 
                BearingSafety4.Text = "UNSAFE" 
            End If 
 
            If ScrEndBearing >= Smax Then 
                BearingSafety4.ForeColor = Color.Blue 
                BearingSafety4.Text = "SAFE" 
            Else 
                BearingSafety4.ForeColor = Color.Red 
                BearingSafety4.Text = "UNSAFE" 
            End If 
 
            'Friction failure checks 
            If ScrFriction < 0 Then 
                MsgBox("Projected critical scour value is negative, therefore maximum 
applied load is greater than pile capacity.") 
                FrictionSafety4.ForeColor = Color.Red 
                FrictionSafety4.Text = "UNSAFE" 
            End If 
 
            If ScrFriction >= Smax Then 
                FrictionSafety4.ForeColor = Color.Blue 
                FrictionSafety4.Text = "SAFE" 
            Else 
                FrictionSafety4.ForeColor = Color.Red 
                FrictionSafety4.Text = "UNSAFE" 
            End If 
 
            'Kickout failure check (input recieved, checked later) 
309
            Las4 = Val(Lbg4.Text) - Val(Scour4.Text) 
            If Las4 < 2.5 Then 
                MsgBox("Pile in Column 4 unsafe for kick-out.  Take preventative measures 
such as riprap.") 
            ElseIf 2.5 <= Las4 And Las4 < 5 Then 
                MsgBox("Pile in Column 4 in danger of being unsafe for kick-out after 
future scour events.  Take preventative measures such as riprap.") 
            Else 
            End If 
 
        End If 
 
        'Repeat for bent column 5 
        If Val(BentNo5.Text) <> 0 Then 
            'Gather input from user 
            Lbg = Val(Lbg5.Text) 'ft 
            Smax = Val(Scour5.Text) 'ft 
            DrivingResistance = Val(DrivingResist5.Text) 'bpi 
            HammerEnergy = Val(HammerEnergy5.Text) 'ft-lbs 
            If HammerType = "Single Acting Air/Steam (Assumed 67% Efficient)" Then 
                HammerEnergy = 0.67 * HammerEnergy 
            ElseIf HammerType = "Double Acting Air/Steam (Assumed 50% Efficient)" Then 
                HammerEnergy = 0.5 * HammerEnergy 
            ElseIf HammerType = "Diesel (Assumed 80% Efficient)" Then 
                HammerEnergy = 0.8 * HammerEnergy 
            Else 
                HammerEnergy = 0.5 * HammerEnergy 
            End If 
 
            'Send input to Plunging Functions module 
            ScrEndBearing = CritScourPlunging_EndBearing(HammerEnergy, DrivingResistance, 
PMaxPlunge, Lbg) 
            EndBearingCapacity = EndBearingCapacityEval(HammerEnergy, DrivingResistance, 
Smax, Lbg) 
            ScrFriction = CritScourPlunging_Friction(HammerEnergy, DrivingResistance, 
PMaxPlunge, Lbg) 
            FrictionCapacity = FrictionCapacityEval(HammerEnergy, DrivingResistance, 
Smax, Lbg) 
 
            'Output results back to form 
            EndBear5.Text = EndBearingCapacity.ToString("###0.00") 
            BearCritScour5.Text = ScrEndBearing.ToString("###0.00") 
            FrictionCapacity5.Text = FrictionCapacity.ToString("###0.00") 
            FrictionCritScour5.Text = ScrFriction.ToString("###0.00") 
 
            'Format for safe/unsafe checks 
            'End bearing failure checks 
            If ScrEndBearing < 0 Then 
                MsgBox("Projected critical scour value is negative, therefore maximum 
applied load is greater than pile capacity.") 
                BearingSafety5.ForeColor = Color.Red 
                BearingSafety5.Text = "UNSAFE" 
            End If 
 
            If ScrEndBearing >= Smax Then 
                BearingSafety5.ForeColor = Color.Blue 
                BearingSafety5.Text = "SAFE" 
            Else 
310
                BearingSafety5.ForeColor = Color.Red 
                BearingSafety5.Text = "UNSAFE" 
            End If 
 
            'Friction failure checks 
            If ScrFriction < 0 Then 
                MsgBox("Projected critical scour value is negative, therefore maximum 
applied load is greater than pile capacity.") 
                FrictionSafety5.ForeColor = Color.Red 
                FrictionSafety5.Text = "UNSAFE" 
            End If 
 
            If ScrFriction >= Smax Then 
                FrictionSafety5.ForeColor = Color.Blue 
                FrictionSafety5.Text = "SAFE" 
            Else 
                FrictionSafety5.ForeColor = Color.Red 
                FrictionSafety5.Text = "UNSAFE" 
            End If 
 
            'Kickout failure check (input recieved, checked later) 
            Las5 = Val(Lbg5.Text) - Val(Scour5.Text) 
            If Las5 < 2.5 Then 
                MsgBox("Pile in Column 5 unsafe for kick-out.  Take preventative measures 
such as riprap.") 
            ElseIf 2.5 <= Las5 And Las5 < 5 Then 
                MsgBox("Pile in Column 5 in danger of being unsafe for kick-out after 
future scour events.  Take preventative measures such as riprap.") 
            Else 
            End If 
 
        End If 
 
        'Kickout failure check to send to conclusion module 
        If (Val(BentNo1.Text) <> 0 And Las1 < 2.5) Or (Val(BentNo2.Text) <> 0 And Las2 < 
2.5) Or (Val(BentNo3.Text) <> 0 And Las3 < 2.5) Or (Val(BentNo4.Text) <> 0 And Las4 < 
2.5) Or (Val(BentNo5.Text) <> 0 And Las5 < 2.5) Then 
            KickOut = "Unsafe!" 
        ElseIf (Val(BentNo1.Text) <> 0 And 2.5 <= Las1 And Las1 < 5) Or 
(Val(BentNo2.Text) <> 0 And 2.5 <= Las2 And Las2 < 5) Or (Val(BentNo3.Text) <> 0 And 2.5 
<= Las3 And Las3 < 5) Or (Val(BentNo4.Text) <> 0 And 2.5 <= Las4 And Las4 < 5) Or 
(Val(BentNo5.Text) <> 0 And 2.5 <= Las5 And Las5 < 5) Then 
            KickOut = "Possibly unsafe for future scour events!" 
        Else : KickOut = "Safe!" 
            MsgBox("Piles are safe from kick-out failure.") 
 
        End If 
 
        'Send evaluation to Master Plunging Failure variable 
        If BearingSafety1.Text = "UNSAFE" Or BearingSafety2.Text = "UNSAFE" Or 
BearingSafety3.Text = "UNSAFE" Or BearingSafety4.Text = "UNSAFE" Or BearingSafety5.Text = 
"UNSAFE" Then 
            BearingSafe = "False" 
        End If 
 
        If FrictionSafety1.Text = "UNSAFE" Or FrictionSafety2.Text = "UNSAFE" Or 
FrictionSafety3.Text = "UNSAFE" Or FrictionSafety4.Text = "UNSAFE" Or 
FrictionSafety5.Text = "UNSAFE" Then 
311
            FrictionSafe = "False" 
        End If 
 
        If BearingSafe = "False" Then 
            If FrictionSafe = "False" Then 
                Plunging = "Unsafe in both Bearing and Friction!" 
            Else : Plunging = "Unsafe in Bearing!" 
            End If 
        Else 
            If FrictionSafe = "False" Then 
                Plunging = "Unsafe in Friction!" 
            Else 
                Plunging = "Safe!" 
 
            End If 
        End If 
 
        PictureBox2.Visible = True 
        EnterArrow.Visible = False 
        Label2.Visible = True 
    End Sub 
 
 
    Private Sub ClrButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ClrButton.Click 
        'Clear all inputs 
        BentNo1.Text = "" 
        DrivingResist1.Text = "" 
        HammerEnergy1.Text = "" 
        Scour1.Text = "" 
        Lbg1.Text = "" 
        EndBear1.Text = "" 
        BearCritScour1.Text = "" 
        BearingSafety1.Text = "" 
        FrictionCapacity1.Text = "" 
        FrictionCritScour1.Text = "" 
        FrictionSafety1.Text = "" 
 
        BentNo2.Text = "" 
        DrivingResist2.Text = "" 
        HammerEnergy2.Text = "" 
        Scour2.Text = "" 
        Lbg2.Text = "" 
        EndBear2.Text = "" 
        BearCritScour2.Text = "" 
        BearingSafety2.Text = "" 
        FrictionCapacity2.Text = "" 
        FrictionCritScour2.Text = "" 
        FrictionSafety2.Text = "" 
 
        BentNo3.Text = "" 
        DrivingResist3.Text = "" 
        HammerEnergy3.Text = "" 
        Scour3.Text = "" 
        Lbg3.Text = "" 
        EndBear3.Text = "" 
        BearCritScour3.Text = "" 
        BearingSafety3.Text = "" 
312
        FrictionCapacity3.Text = "" 
        FrictionCritScour3.Text = "" 
        FrictionSafety3.Text = "" 
 
        BentNo4.Text = "" 
        DrivingResist4.Text = "" 
        HammerEnergy4.Text = "" 
        Scour4.Text = "" 
        Lbg4.Text = "" 
        EndBear4.Text = "" 
        BearCritScour4.Text = "" 
        BearingSafety4.Text = "" 
        FrictionCapacity4.Text = "" 
        FrictionCritScour4.Text = "" 
        FrictionSafety4.Text = "" 
 
        BentNo5.Text = "" 
        DrivingResist5.Text = "" 
        HammerEnergy5.Text = "" 
        Scour5.Text = "" 
        Lbg5.Text = "" 
        EndBear5.Text = "" 
        BearCritScour5.Text = "" 
        BearingSafety5.Text = "" 
        FrictionCapacity5.Text = "" 
        FrictionCritScour5.Text = "" 
        FrictionSafety5.Text = "" 
 
        EnterArrow.Visible = True 
        Label2.Visible = False 
        PictureBox2.Visible = False 
 
    End Sub 
 
    Private Sub Cont_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Cont.Click 
 
 
        vBentNo1 = BentNo1.Text 
        vBentNo2 = BentNo2.Text 
        vBentNo3 = BentNo3.Text 
        vBentNo4 = BentNo4.Text 
        vBentNo5 = BentNo5.Text 
 
        vHammerEnergy1 = HammerEnergy1.Text 
        vHammerEnergy2 = HammerEnergy2.Text 
        vHammerEnergy3 = HammerEnergy3.Text 
        vHammerEnergy4 = HammerEnergy4.Text 
        vHammerEnergy5 = HammerEnergy5.Text 
 
 
        vDrivingResistance1 = DrivingResist1.Text 
        vDrivingResistance2 = DrivingResist2.Text 
        vDrivingResistance3 = DrivingResist3.Text 
        vDrivingResistance4 = DrivingResist4.Text 
        vDrivingResistance5 = DrivingResist5.Text 
 
        If Las1 <> 0 Then 
313
            vLas1 = Las1 
        End If 
        If Las2 <> 0 Then 
            vLas2 = Las2 
        End If 
        If Las3 <> 0 Then 
            vLas3 = Las3 
        End If 
        If Las4 <> 0 Then 
            vLas4 = Las4 
        End If 
        If Las5 <> 0 Then 
            vLas5 = Las5 
        End If 
 
        vFrictionCapacity1 = FrictionCapacity1.Text 
        vFrictionCapacity2 = FrictionCapacity2.Text 
        vFrictionCapacity3 = FrictionCapacity3.Text 
        vFrictionCapacity4 = FrictionCapacity4.Text 
        vFrictionCapacity5 = FrictionCapacity5.Text 
 
        vFrictionCritScour1 = FrictionCritScour1.Text 
        vFrictionCritScour2 = FrictionCritScour2.Text 
        vFrictionCritScour3 = FrictionCritScour3.Text 
        vFrictionCritScour4 = FrictionCritScour4.Text 
        vFrictionCritScour5 = FrictionCritScour5.Text 
 
        vFrictionSafety1 = FrictionSafety1.Text 
        vFrictionSafety2 = FrictionSafety2.Text 
        vFrictionSafety3 = FrictionSafety3.Text 
        vFrictionSafety4 = FrictionSafety4.Text 
        vFrictionSafety5 = FrictionSafety5.Text 
 
        vEndBear1 = EndBear1.Text 
        vEndBear2 = EndBear2.Text 
        vEndBear3 = EndBear3.Text 
        vEndBear4 = EndBear4.Text 
        vEndBear5 = EndBear5.Text 
 
 
        vBearCritScour1 = BearCritScour1.Text 
        vBearCritScour2 = BearCritScour2.Text 
        vBearCritScour3 = BearCritScour3.Text 
        vBearCritScour4 = BearCritScour4.Text 
        vBearCritScour5 = BearCritScour5.Text 
 
        vBearingSafety1 = BearingSafety1.Text 
        vBearingSafety2 = BearingSafety2.Text 
        vBearingSafety3 = BearingSafety3.Text 
        vBearingSafety4 = BearingSafety4.Text 
        vBearingSafety5 = BearingSafety5.Text 
        'Show next form 
        My.Forms.BucklingEval.Show() 
        WindowState = FormWindowState.Minimized 
 
 
    End Sub 
 
314
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Button2.Click 
        'Exit routine 
        End 
    End Sub 
 
    Private Sub HelpToolStripButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles HelpToolStripButton.Click 
        My.Forms.PlungingHelp.ShowDialog() 
    End Sub 
End Class 
 
Public Class PlungingHelp 
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Button1.Click 
        Me.DialogResult = DialogResult.OK 
    End Sub 
 
End Class 
 
 
315
 
 
 
Appendix D.5 Buckling Evaluation and Related Modules 
Public Class BucklingEval 
 
    Public LCritNonSidesway, LCritSideswayBraced, LCritSideswayUnbraced As Single 
    Public SCritNonSidesway, SCritSideswayBraced, SCritSideswayUnbraced As Single 
 
    Private Sub ContinueButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ContinueButton.Click 
        'Show next form 
        My.Forms.PushoverEvaluation.Show() 
        WindowState = FormWindowState.Minimized 
    End Sub 
 
    Private Sub ExitButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ExitButton.Click 
        'Exit routine 
        End 
    End Sub 
 
    Private Sub BucklingEval_Load(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Load 
 
        'Show previous inputs in form 
        XBracedText.Text = Bracing 
        DiameterText.Text = Dia.ToString("###0") 
        HeightText.Text = BentHeight.ToString("###0.0") 
        ScourText.Text = Smax.ToString("###0.0") 
        LasText.Text = Las.ToString("###0.0") 
        PmaxAppliedText.Text = PileAppliedMax.ToString("###0.0") 
 
        'Determine Effective Diameter of Pile for longitudinal and unbraced assuming 
taper of 0.12in/ft 
        Lag = BentHeight + Smax - 1.25 'ft 
        DiaEff = Dia - (((2 / 3) * Lag) * 0.12) 'in 
 
        'Determine Effective Diameter for Transverse below x-bracing calcs 
        LagBelowBrace = Smax + 1.25 
        DiaEffBelowBrace = Dia - ((((2 / 3) * LagBelowBrace) + (BentHeight - 2.5)) * 
0.12) 'in 
 
        'Determine Effective Moments of Inertia 
        Pi = 3.14159265 
        IEff = (Pi * (DiaEff ^ 4)) / 64 
        IEffBelowBrace = (Pi * (DiaEffBelowBrace ^ 4)) / 64 
        ModulusE = 1800 'ksi 
 
        'Determine C1 based off embedment after scour 
        If Las >= 8 Then 
            C1 = 2 'fixed 
316
        ElseIf Las >= 4 And Las < 8 Then 
            C1 = 1.5 'partially fixed 
        Else 
            C1 = 1 'pinned 
        End If 
 
        C2 = 0.5 
        C3 = 1 / 6 
 
        'X-Braced Buckling Evaluation 
        If Bracing = "X-braced" Then 
            If WaterDepth = 0 Then 'bents out of water  
                LCritNonSidesway = LCrit_NonSidesway(PileAppliedMax, IEff, C1) 
                SCritNonSidesway = SCrit_NonSidesway(LCritNonSidesway, BentHeight) 
 
                LCritSideswayBraced = LCrit_SideswayBraced(PileAppliedMax, 
IEffBelowBrace, C2) 
                SCritSideswayBraced = SCrit_SideswayBraced(LCritSideswayBraced, 
BentHeight) 
 
                If SCritNonSidesway < SCritSideswayBraced Then 'Non-Sidesway is 
controlling mode 
                    FailureModeText.Text = "Nonsidesway buckling in the longitudinal 
direction" 
                    LcrText.Text = LCritNonSidesway.ToString("###0.0") 
                    ScourCritText.Text = SCritNonSidesway.ToString("###0.0") 
                    IeffText.Text = IEff.ToString("###0.00") 
 
                    'Compare to max predicted scour 
                    If Smax > SCritNonSidesway Then 
                        BucklingSafetyText.ForeColor = Color.Red 
                        BucklingSafetyText.Text = "Unsafe!" 
                        Buckling = "Unsafe!" 
                    Else 
                        BucklingSafetyText.ForeColor = Color.Blue 
                        BucklingSafetyText.Text = "Safe!" 
                        Buckling = "Safe!" 
                    End If 
 
                Else 
                    FailureModeText.Text = "Transverse sidesway buckling below the X-
bracing" 
                    'need to convert Lcrit to be from pile cap i.e. add in H - 2.5' 
                    LCritSideswayBraced = LCritSideswayBraced + BentHeight - 2.5 ' 
                    LcrText.Text = LCritSideswayBraced.ToString("###0.0") 
                    ScourCritText.Text = SCritSideswayBraced.ToString("###0.0") 
                    IeffText.Text = IEffBelowBrace.ToString("###0.00") 
 
                    'Compare to max predicted scour 
                    If Smax > SCritSideswayBraced Then 
                        BucklingSafetyText.ForeColor = Color.Red 
                        BucklingSafetyText.Text = "Unsafe!" 
                        Buckling = "Unsafe!" 
                    Else 
                        BucklingSafetyText.ForeColor = Color.Blue 
                        BucklingSafetyText.Text = "Safe!" 
                        Buckling = "Safe!" 
                    End If 
317
                End If 
            Else 'bents over water (repeated calcs, but transverse direction uses diff 
function 
                LCritNonSidesway = LCrit_NonSidesway(PileAppliedMax, IEff, C1) 
                SCritNonSidesway = SCrit_NonSidesway(LCritNonSidesway, BentHeight) 
 
                LCritSideswayBraced = LCrit_SideswayBraced(PileAppliedMax, 
IEffBelowBrace, C2) 
                SCritSideswayBraced = SCrit_SideswayBracedOverWater(LCritSideswayBraced, 
BentHeight) 
 
                If SCritNonSidesway < SCritSideswayBraced Then 'Non-Sidesway is 
controlling mode 
                    FailureModeText.Text = "Nonsidesway buckling in the longitudinal 
direction" 
                    LcrText.Text = LCritNonSidesway.ToString("###0.0") 
                    ScourCritText.Text = SCritNonSidesway.ToString("###0.0") 
                    IeffText.Text = IEff.ToString("###0.00") 
 
                    'Compare to max predicted scour 
                    If Smax > SCritNonSidesway Then 
                        BucklingSafetyText.ForeColor = Color.Red 
                        BucklingSafetyText.Text = "Unsafe!" 
                        Buckling = "Unsafe!" 
                    Else 
                        BucklingSafetyText.ForeColor = Color.Blue 
                        BucklingSafetyText.Text = "Safe!" 
                        Buckling = "Safe!" 
                    End If 
 
                Else 
                    FailureModeText.Text = "Transverse sidesway buckling below the X-
bracing" 
                    'need to convert Lcrit to be from pile cap i.e. add in H - 2.5' 
                    LCritSideswayBraced = LCritSideswayBraced + BentHeight - 2.5 ' 
                    LcrText.Text = LCritSideswayBraced.ToString("###0.0") 
                    ScourCritText.Text = SCritSideswayBraced.ToString("###0.0") 
                    IeffText.Text = IEffBelowBrace.ToString("###0.00") 
 
                    'Compare to max predicted scour 
                    If Smax > SCritSideswayBraced Then 
                        BucklingSafetyText.ForeColor = Color.Red 
                        BucklingSafetyText.Text = "Unsafe!" 
                        Buckling = "Unsafe!" 
                    Else 
                        BucklingSafetyText.ForeColor = Color.Blue 
                        BucklingSafetyText.Text = "Safe!" 
                        Buckling = "Safe!" 
                    End If 
                End If 
            End If 
            'Unbraced Buckling Evaluation 
        Else 
            LCritSideswayUnbraced = LCrit_SideswayUnBraced(PileAppliedMax, IEff, C3) 
            SCritSideswayUnbraced = SCrit_SideswayUnBraced(LCritSideswayUnbraced, 
BentHeight) 
 
            FailureModeText.Text = "Transverse sidesway buckling from pile cap to NGL" 
318
            LcrText.Text = LCritSideswayUnbraced.ToString("###0.0") 
            ScourCritText.Text = SCritSideswayUnbraced.ToString("###0.0") 
            IeffText.Text = IEff.ToString("###0.00") 
            'Compare to max predicted scour 
            If Smax > SCritSideswayUnbraced Then 
                BucklingSafetyText.ForeColor = Color.Red 
                BucklingSafetyText.Text = "Unsafe!" 
                Buckling = "Unsafe!" 
            Else 
                BucklingSafetyText.ForeColor = Color.Blue 
                BucklingSafetyText.Text = "Safe!" 
                Buckling = "Safe!" 
            End If 
 
        End If 
 
        'put text output into new variables for output report 
        IEffTextVal = Val(IeffText.Text) 
        FailureModeTextVal = FailureModeText.Text 
        LcrTextVal = Val(LcrText.Text) 
        ScourCritTextVal = Val(ScourCritText.Text) 
 
    End Sub 
 
End Class 
 
Module BucklingFunctions 
 
    Public E As Single 
 
    'Buckling Functions include FS 1.33 
    'Assumed brace located 1.25' above OGL for all except bent over water calc 
 
    'Buckling NonSidesway  
    Function LCrit_NonSidesway(ByVal PApplied As Single, ByVal EffInertia As Single, 
ByVal C As Single) 
        LCrit_NonSidesway = (((C * (Pi ^ 2) * ModulusE * EffInertia) / (1.33 * PApplied)) 
^ (0.5)) / 12 'ft 
    End Function 
 
    Function SCrit_NonSidesway(ByVal LCrit As Single, ByVal Ht As Single) 
        SCrit_NonSidesway = LCrit + 1.25 - Ht 'ft 
    End Function 
 
    'Buckling Sidesway below X-Brace 
    Function LCrit_SideswayBraced(ByVal PApplied As Single, ByVal EffInertia As Single, 
ByVal C As Single) 
        LCrit_SideswayBraced = (((C * (Pi ^ 2) * ModulusE * EffInertia) / (1.33 * 
PApplied)) ^ (0.5)) / 12 'ft 
    End Function 
 
    Function SCrit_SideswayBraced(ByVal LCrit As Single, ByVal Ht As Single) 
        SCrit_SideswayBraced = LCrit - 1.25 'ft 
    End Function 
 
    'BucklingSidesway below X-brace and bent over water 
    Function SCrit_SideswayBracedOverWater(ByVal LCrit As Single, ByVal Ht As Single) 
        SCrit_SideswayBracedOverWater = LCrit - (1.25 + WaterDepth) 
319
    End Function 
 
    'Unbraced Buckling Sidesway 
    Function LCrit_SideswayUnBraced(ByVal PApplied As Single, ByVal EffInertia As Single, 
ByVal C As Single) 
        LCrit_SideswayUnBraced = (((C * (Pi ^ 2) * ModulusE * EffInertia) / (1.33 * 
PApplied)) ^ (0.5)) / 12 'ft 
    End Function 
 
    Function SCrit_SideswayUnBraced(ByVal LCrit As Single, ByVal Ht As Single) 
        SCrit_SideswayUnBraced = LCrit + 1.25 - Ht 'ft 
    End Function 
 
End Module 
 
 
320
 
 
 
Appendix D.6 Bent Pushover Evaluation Module 
Public Class PushoverEvaluation 
 
    Private Sub ContinueButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ContinueButton.Click 
        'Shows next form 
        My.Forms.BeamColumnEval.Show() 
        WindowState = FormWindowState.Minimized 
    End Sub 
 
    Private Sub PushoverEval_Load(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Load 
        'Display previous inputs 
        SpanText.Text = Span.ToString("###0.0") 
        BentMaxLoadText.Text = BentAppliedMax.ToString("###0.0") 
        DebrisRaftText.Text = DebrisRaft 
 
        'Determine raft force based on bridge span length 
        If DebrisRaft = "Yes" Then 
            If Span <= 25 Then 
                RaftForce = 8.62 'kips 'smaller raft 
            Else 
                RaftForce = 12.93 'kips 'larger raft 
            End If 
        Else 
            'Minimum assumed force if no raft present 
            RaftForce = 1.5 'kips 
        End If 
 
        RaftForceText.Text = RaftForce 
        PLoadMax = BentAppliedMax / NoPiles 
        PLoadText.Text = PLoadMax.ToString("###0.0") 
 
        'only unsafe bent is unbraced 3-pile, 12 dia, 16ft high, P load 60, large raft,   
  & and maximum scour     
 
        If Smax > 20 Then 'out of range cases 
            PushoverSafetyText.ForeColor = Color.Red 
            PushoverSafetyText.Text = "Out of Range" 
            PushoverCritScourText.Text = "Out of Range" 
            Pushover = "Out of Range" 
            MsgBox("Screening tool cannot evaluate bent pushover for scour values greater 
  & than 20 feet.") 
        Else 
            If Bracing = "X-braced" Then 
                If BentHeight > 20 Then 'out of range cases 
                    PushoverSafetyText.ForeColor = Color.Red 
                    PushoverSafetyText.Text = "Out of Range" 
                    PushoverCritScourText.Text = "Out of Range" 
321
                    Pushover = "Out of Range" 
                    MsgBox("Screening tool cannot evaluate bent pushover for braced bent  
   & heights greater than 20 feet.") 
                Else 
                    PushoverSafetyText.ForeColor = Color.Blue 
                    PushoverSafetyText.Text = "Safe!" 
                    PushoverCritScourText.Text = "Greater than 20ft" 
                    Pushover = "Safe!" 
                End If 
            Else 'unbraced cases 
                If BentHeight > 16 Then 'out of range cases 
                    PushoverSafetyText.ForeColor = Color.Red 
                    PushoverSafetyText.Text = "Out of Range" 
                    PushoverCritScourText.Text = "Out of Range" 
                    Pushover = "Out of Range" 
                    MsgBox("Screening tool cannot evaluate bent pushover for unbraced  
   & bent heights greater than 16 feet.") 
                Else 
                    If Dia = 14 Then 
                        PushoverSafetyText.ForeColor = Color.Blue 
                        PushoverSafetyText.Text = "Safe!" 
                        PushoverCritScourText.Text = "Greater than 20ft" 
                        Pushover = "Safe!" 
                    Else '12in cases 
                        If NoPiles = 3 Then 
                            If BentHeight > 12 Then 'ft 
                                If PLoadMax <= 40 Then 'smaller gravity load cases 
                                    PushoverSafetyText.ForeColor = Color.Blue 
                                    PushoverSafetyText.Text = "Safe!" 
                                    PushoverCritScourText.Text = "Greater than 20ft" 
                                    Pushover = "Safe!" 
                                Else 
                                    If Span >= 25 Then 'large raft cases 
                                        If Smax > 15 Then 
                                            PushoverSafetyText.ForeColor = Color.Red 
                                            PushoverSafetyText.Text = "Unsafe!" 
                                            PushoverCritScourText.Text = "Greater than  
       & 15ft" 
                                            Pushover = "Unsafe!" 
                                        Else 'smaller scour cases 
                                            PushoverSafetyText.ForeColor = Color.Blue 
                                            PushoverSafetyText.Text = "Safe!" 
                                            PushoverCritScourText.Text = "Greater than  
       & 20ft" 
                                            Pushover = "Safe!" 
                                        End If 
                                    Else 'smaller raft force cases 
                                        PushoverSafetyText.ForeColor = Color.Blue 
                                        PushoverSafetyText.Text = "Safe!" 
                                        PushoverCritScourText.Text = "Greater than 20ft" 
                                        Pushover = "Safe!" 
                                    End If 
 
                                End If 
                            Else 'smaller bent height cases 
                                PushoverSafetyText.ForeColor = Color.Blue 
                                PushoverSafetyText.Text = "Safe!" 
                                PushoverCritScourText.Text = "Greater than 20ft" 
322
                                Pushover = "Safe!" 
                            End If 
 
                        Else 'other number of pile cases 
                            PushoverSafetyText.ForeColor = Color.Blue 
                            PushoverSafetyText.Text = "Safe!" 
                            PushoverCritScourText.Text = "Greater than 20ft" 
                            Pushover = "Safe!" 
                        End If 
                    End If 
                End If 
            End If 
            'send to printing module 
            PushoverCritScourTextVal = PushoverCritScourText.Text 
        End If 
 
    End Sub 
 
    Private Sub ExitButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ExitButton.Click 
        'Exit routine 
        End 
    End Sub 
End Class 
 
323
 
 
 
Appendix D.7 Beam-Column Evaluation Module 
Public Class BeamColumnEval 
 
    Private Sub BeamColumnEval_Load(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Load 
        'Show all inputs in form 
        DebrisRaftText.Text = DebrisRaft 
        DiameterText.Text = Dia.ToString("###0") 
        XBracedText.Text = Bracing 
        HeightText.Text = BentHeight.ToString("###0.0") 
        ScourText.Text = Smax.ToString("###0.0") 
        SpanText.Text = Span.ToString("###0.0") 
 
        'Beam-Column Evaulations 
        If DebrisRaft = "No" Then 
            BeamColSafetyText.ForeColor = Color.Blue 
            BeamColSafetyText.Text = "Safe!" 
            BeamColumn = "Safe!" 
 
        Else 
            If Bracing = "X-braced" Then 
                BeamColSafetyText.ForeColor = Color.Blue 
                BeamColSafetyText.Text = "Safe!" 
                BeamColumn = "Safe!" 
                CritScourBeamCol = "Greater than 20ft" 
                CritScourBeamText.Text = CritScourBeamCol 
 
            Else 'Unbraced cases 
                If BentHeight > 12 Then 'ft  
                    BeamColSafetyText.ForeColor = Color.Red 
                    BeamColSafetyText.Text = "Out of Range" 
                    BeamColumn = "Out of Tool's Range" 
                    CritScourBeamCol = "UNKNOWN" 
                    CritScourBeamText.Text = CritScourBeamCol 
                Else 
                    If BentHeight > 8 Then 
                        If Dia = 14 Then '14in cases; 12 to 8ft bents 
                            If RaftForce <= 8.62 Then 'kips 
                                If PLoad <= 44 Then 'kips  
                                    CritScourBeamCol = "10" 
                                    CritScourBeamText.Text = CritScourBeamCol 
                                    If Smax <= 10 Then 'ft 
                                        BeamColSafetyText.ForeColor = Color.Blue 
                                        BeamColSafetyText.Text = "Safe!" 
                                        BeamColumn = "Safe!" 
                                    Else 
                                        BeamColSafetyText.ForeColor = Color.Red 
                                        BeamColSafetyText.Text = "Unsafe!" 
                                        BeamColumn = "Unsafe!" 
324
                                    End If 
                                Else 'larger p-load cases 
                                    CritScourBeamCol = "5" 
                                    CritScourBeamText.Text = CritScourBeamCol 
                                    If Smax <= 5 Then 'ft  
                                        BeamColSafetyText.ForeColor = Color.Blue 
                                        BeamColSafetyText.Text = "Safe!" 
                                        BeamColumn = "Safe!" 
                                    Else 
                                        BeamColSafetyText.ForeColor = Color.Red 
                                        BeamColSafetyText.Text = "Unsafe!" 
                                        BeamColumn = "Unsafe!" 
                                    End If 
                                End If 
                            Else 'Larger debris raft 
                                CritScourBeamCol = "10" 
                                CritScourBeamText.Text = CritScourBeamCol 
                                If PLoad <= 36 Then 'kips  
                                    If Smax <= 10 Then 'ft 
                                        BeamColSafetyText.ForeColor = Color.Blue 
                                        BeamColSafetyText.Text = "Safe!" 
                                        BeamColumn = "Safe!" 
                                    Else 
                                        BeamColSafetyText.ForeColor = Color.Red 
                                        BeamColSafetyText.Text = "Unsafe!" 
                                        BeamColumn = "Unsafe!" 
                                    End If 
                                Else 'larger p-load cases 
                                    CritScourBeamCol = "5" 
                                    CritScourBeamText.Text = CritScourBeamCol 
                                    If Smax <= 5 Then 'ft  
                                        BeamColSafetyText.ForeColor = Color.Blue 
                                        BeamColSafetyText.Text = "Safe!" 
                                        BeamColumn = "Safe!" 
                                    Else 
                                        BeamColSafetyText.ForeColor = Color.Red 
                                        BeamColSafetyText.Text = "Unsafe!" 
                                        BeamColumn = "Unsafe!" 
                                    End If 
                                End If 
                            End If 
                        Else '12in diameter cases 
                            If RaftForce <= 8.62 Then 'small raft cases 
                                If PLoad <= 32 Then 'kips 
                                    CritScourBeamCol = "5" 
                                    CritScourBeamText.Text = CritScourBeamCol 
                                    If Smax <= 5 Then 'ft 
                                        BeamColSafetyText.ForeColor = Color.Blue 
                                        BeamColSafetyText.Text = "Safe!" 
                                        BeamColumn = "Safe!" 
                                    Else 
                                        BeamColSafetyText.ForeColor = Color.Red 
                                        BeamColSafetyText.Text = "Unsafe!" 
                                        BeamColumn = "Unsafe!" 
                                    End If 
                                Else 'larger pload cases 
                                    CritScourBeamCol = "0" 
                                    CritScourBeamText.Text = CritScourBeamCol 
325
                                    BeamColSafetyText.ForeColor = Color.Red 
                                    BeamColSafetyText.Text = "Unsafe!" 
                                    BeamColumn = "Unsafe!" 
                                End If 
                            Else 'larger raft cases 
                                If PLoad <= 20 Then 'kips 
                                    CritScourBeamCol = "5" 
                                    CritScourBeamText.Text = CritScourBeamCol 
                                    If Smax <= 5 Then 'ft 
                                        BeamColSafetyText.ForeColor = Color.Blue 
                                        BeamColSafetyText.Text = "Safe!" 
                                        BeamColumn = "Safe!" 
                                    Else 
                                        BeamColSafetyText.ForeColor = Color.Red 
                                        BeamColSafetyText.Text = "Unsafe!" 
                                        BeamColumn = "Unsafe!" 
                                    End If 
                                Else 'larger pload cases 
                                    CritScourBeamCol = "0" 
                                    CritScourBeamText.Text = CritScourBeamCol 
                                    BeamColSafetyText.ForeColor = Color.Red 
                                    BeamColSafetyText.Text = "Unsafe!" 
                                    BeamColumn = "Unsafe!" 
                                End If 
                            End If 
                        End If 
 
                    ElseIf BentHeight <= 8 Then 'ft 
                        If Dia = 12 Then '12in cases; less or equal to 8ft bents 
                            If RaftForce <= 8.62 Then 'kips 
                                If PLoad <= 26 Then 'kips  
                                    CritScourBeamCol = "10" 
                                    CritScourBeamText.Text = CritScourBeamCol 
                                    If Smax <= 10 Then 'ft 
                                        BeamColSafetyText.ForeColor = Color.Blue 
                                        BeamColSafetyText.Text = "Safe!" 
                                        BeamColumn = "Safe!" 
                                    Else 
                                        BeamColSafetyText.ForeColor = Color.Red 
                                        BeamColSafetyText.Text = "Unsafe!" 
                                        BeamColumn = "Unsafe!" 
                                    End If 
                                Else 
                                    CritScourBeamCol = "5" 
                                    CritScourBeamText.Text = CritScourBeamCol 
                                    If Smax <= 5 Then 'ft  
                                        BeamColSafetyText.ForeColor = Color.Blue 
                                        BeamColSafetyText.Text = "Safe!" 
                                        BeamColumn = "Safe!" 
                                    Else 
                                        BeamColSafetyText.ForeColor = Color.Red 
                                        BeamColSafetyText.Text = "Unsafe!" 
                                        BeamColumn = "Unsafe!" 
                                    End If 
                                End If 
                            Else 'Larger debris raft 
                                CritScourBeamCol = "5" 
                                CritScourBeamText.Text = CritScourBeamCol 
326
                                If Smax <= 5 Then 'ft 
                                    BeamColSafetyText.ForeColor = Color.Blue 
                                    BeamColSafetyText.Text = "Safe!" 
                                    BeamColumn = "Safe!" 
                                Else 
                                    BeamColSafetyText.ForeColor = Color.Red 
                                    BeamColSafetyText.Text = "Unsafe!" 
                                    BeamColumn = "Unsafe!" 
                                End If 
                            End If 
                        Else '14in diameter cases 
                            CritScourBeamCol = "10" 
                            CritScourBeamText.Text = CritScourBeamCol 
                            If Smax <= 10 Then 'ft 
                                BeamColSafetyText.ForeColor = Color.Blue 
                                BeamColSafetyText.Text = "Safe!" 
                                BeamColumn = "Safe!" 
                            Else 
                                BeamColSafetyText.ForeColor = Color.Red 
                                BeamColSafetyText.Text = "Unsafe!" 
                                BeamColumn = "Unsafe!" 
                            End If 
                        End If 
                    End If 
                End If 
            End If 
        End If 
    End Sub 
 
 
 
    Private Sub ExitButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ExitButton.Click 
        'Exit Routine 
        End 
    End Sub 
 
    Private Sub ContinueButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ContinueButton.Click 
        'Show next form 
        If BeamColSafetyText.Text = "UNKNOWN" Then 
            MsgBox("Screening tool cannot check beam column adequacy of unbraced bent 
heights greater than 12 feet.") 
        Else 
        End If 
        My.Forms.Conclusions.Show() 
        WindowState = FormWindowState.Minimized 
    End Sub 
End Class 
 
327
 
 
 
Appendix D.8 Conclusions and Related Modules 
Public Class Conclusions 
 
    Private Sub ExitButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ExitButton.Click 
        End 
    End Sub 
 
    Private Sub Conclusions_Load(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Load 
        'Output scour evaluations to form 
        'Eval 1: Kickout 
        If KickOut = "Unsafe!" Then 
            KickOutSafety.ForeColor = Color.Red 
            KickOutSafety.Text = KickOut 
        Else 
            KickOutSafety.ForeColor = Color.Blue 
            KickOutSafety.Text = KickOut 
        End If 
 
        'Eval 2: Plunging 
        If Plunging = "Safe!" Then 
            PlungingSafety.ForeColor = Color.Blue 
            PlungingSafety.Text = Plunging 
        Else 
            PlungingSafety.ForeColor = Color.Red 
            PlungingSafety.Text = Plunging 
        End If 
 
        'Eval 3: Buckling 
        If Buckling = "Safe!" Then 
            BucklingSafety.ForeColor = Color.Blue 
            BucklingSafety.Text = Buckling 
        Else 
            BucklingSafety.ForeColor = Color.Red 
            BucklingSafety.Text = Buckling 
        End If 
 
        'Eval4: Pushover 
        If Pushover = "Safe!" Then 
            PushoverSafety.ForeColor = Color.Blue 
            PushoverSafety.Text = Pushover 
        Else 
            PushoverSafety.ForeColor = Color.Red 
            PushoverSafety.Text = Pushover 
        End If 
 
        'Eval5: Beam-Column 
        If BeamColumn = "Safe!" Then 
328
            BeamColumnSafety.ForeColor = Color.Blue 
            BeamColumnSafety.Text = BeamColumn 
        Else 
            BeamColumnSafety.ForeColor = Color.Red 
            BeamColumnSafety.Text = BeamColumn 
        End If 
 
 
    End Sub 
 
    Private Sub PrintToolStripButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles PrintToolStripButton.Click 
        'Show printing form 
        My.Forms.Printing.Show() 
    End Sub 
 
    Private Sub HelpToolStripButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles HelpToolStripButton.Click 
        My.Forms.ConclusionsHelpFile.ShowDialog() 
    End Sub 
End Class 
 
Public Class ConclusionsHelpFile 
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) 
Handles Button1.Click 
        Me.DialogResult = DialogResult.OK 
    End Sub 
End Class 
 
329
 
 
 
Appendix D.9 Printing Output Report Module 
Imports TimberScour.PrintingObjects 
 
 
Public Class Printing 
 
 
    Private Sub PrintButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles PrintButton.Click 
        'gather info for header of printed form 
        Engineer = EngineerText.Text 
        BIN = BINText.Text 
        CheckDate = DateText.Text 
        City = CityText.Text 
        County = CountyText.Text 
        Notes = CommmentText.Text 
 
        Dim header As New PrintingCategory("ALDOT TIMBER STABILITY SCREENING TOOL") 
        header.Items.Add(New PrintingItem("Date", Date.Now.ToString("MM/dd/yyyy"))) 
        header.Items.Add(New PrintingItem("BIN", BIN)) 
        header.Items.Add(New PrintingItem("Checked By", Engineer)) 
        header.Items.Add(New PrintingItem("", City & ", " & County & " County, Alabama")) 
 
        Dim AllSections As New ArrayList() 
 
 
 
        Dim EmptySection As New PrintingSection("Input Parameters") 
        Dim BentPropertiesCat As New PrintingCategory("Bent Properties") 
        BentPropertiesCat.Items.Add(New PrintingItem("Span (ft)", Span)) 
        BentPropertiesCat.Items.Add(New PrintingItem("Bent Height (ft)", BentHeight)) 
        BentPropertiesCat.Items.Add(New PrintingItem("Depth of water under bent (ft)", 
WaterDepth)) 
        BentPropertiesCat.Items.Add(New PrintingItem("Number Of Piles", NoPiles)) 
        BentPropertiesCat.Items.Add(New PrintingItem("Bracing Scheme", Bracing)) 
        BentPropertiesCat.Items.Add(New PrintingItem("Pile Butt Diameter (in.)", Dia)) 
        EmptySection.Categories.Add(BentPropertiesCat) 
 
        Dim PileDInfo As New PrintingCategory("Pile Driving Information") 
        PileDInfo.Items.Add(New PrintingItem("Hammer Type", HammerType)) 
        PileDInfo.Items.Add(New PrintingItem("Efficiency", Efficiency)) 
        EmptySection.Categories.Add(PileDInfo) 
 
        Dim EstimatedScour As New PrintingCategory("Estimated Scour") 
        EstimatedScour.Items.Add(New PrintingItem("Maximum Estimated Scour (ft)", Smax)) 
        EstimatedScour.Items.Add(New PrintingItem("Pile Embedment BEFORE scour (ft)", 
Lbg)) 
        EmptySection.Categories.Add(EstimatedScour) 
 
330
        Dim AppliedLoads As New PrintingCategory("Applied Loads") 
        AppliedLoads.Items.Add(New PrintingItem("Maximum pile applied load (unfactored) 
(kips)", PileAppliedMax)) 
        AppliedLoads.Items.Add(New PrintingItem("Maximum bent applied load (unfactored) 
(kips)", BentAppliedMax)) 
        EmptySection.Categories.Add(AppliedLoads) 
 
        AllSections.Add(EmptySection) 
 
        Dim StabilityEvalSection As New PrintingSection("Stability Evaluation") 
        Dim KickOutCat As New PrintingCategory("Kick-out") 
        KickOutCat.Items.Add(New PrintingItem("Pile Embedment AFTER scour of most 
critical pile (ft)", Las)) 
        KickOutCat.Items.Add(New PrintingItem("Safety", KickOut)) 
        StabilityEvalSection.Categories.Add(KickOutCat) 
 
        Dim BucklingCat As New PrintingCategory("Buckling") 
        BucklingCat.Items.Add(New PrintingItem("Effective Moment of Inertia (in)", 
IEffTextVal)) 
        BucklingCat.Items.Add(New PrintingItem("Buckling Mode", FailureModeTextVal)) 
        BucklingCat.Items.Add(New PrintingItem("Critical Buckling Length(ft)", LcrTextVal 
& " (measured from the bent cap connection to the new ground line)")) 
        BucklingCat.Items.Add(New PrintingItem("Critical Scour (ft)", ScourCritTextVal)) 
        BucklingCat.Items.Add(New PrintingItem("Safety", Buckling)) 
        StabilityEvalSection.Categories.Add(BucklingCat) 
 
        Dim PushoverCat As New PrintingCategory("Pushover") 
        PushoverCat.Items.Add(New PrintingItem("Raft Force (kips)", RaftForce)) 
        PushoverCat.Items.Add(New PrintingItem("Gravity Load (kips)", PloadMax)) 
        PushoverCat.Items.Add(New PrintingItem("Critical Scour (ft)", 
PushoverCritScourTextVal)) 
        PushoverCat.Items.Add(New PrintingItem("Safety", Pushover)) 
        StabilityEvalSection.Categories.Add(PushoverCat) 
 
        Dim BeamColCat As New PrintingCategory("Beam-Column") 
        BeamColCat.Items.Add(New PrintingItem("Safety", BeamColumn)) 
        BeamColCat.Items.Add(New PrintingItem("Critical Scour (ft)", CritScourBeamCol)) 
        StabilityEvalSection.Categories.Add(BeamColCat) 
 
        AllSections.Add(StabilityEvalSection) 
 
        Dim PlungingSection As New PrintingSection(" ") 
        Dim pEmptyCat As New PrintingCategory("Plunging") 
        Dim PileItem As New PrintingItem("Pile") 
        PileItem.Values.Add(vBentNo1) 
        PileItem.Values.Add(vBentNo2) 
        PileItem.Values.Add(vBentNo3) 
        PileItem.Values.Add(vBentNo4) 
        PileItem.Values.Add(vBentNo5) 
        pEmptyCat.Items.Add(PileItem) 
 
        Dim HammerEnergyItem As New PrintingItem("Hammer Rated Energy (lb-ft)") 
        HammerEnergyItem.Values.Add(vHammerEnergy1) 
        HammerEnergyItem.Values.Add(vHammerEnergy2) 
        HammerEnergyItem.Values.Add(vHammerEnergy3) 
        HammerEnergyItem.Values.Add(vHammerEnergy4) 
        HammerEnergyItem.Values.Add(vHammerEnergy5) 
        pEmptyCat.Items.Add(HammerEnergyItem) 
331
 
        Dim DrivingResItem As New PrintingItem("Driving Resistance (bpi)") 
        DrivingResItem.Values.Add(vDrivingResistance1) 
        DrivingResItem.Values.Add(vDrivingResistance2) 
        DrivingResItem.Values.Add(vDrivingResistance3) 
        DrivingResItem.Values.Add(vDrivingResistance4) 
        DrivingResItem.Values.Add(vDrivingResistance5) 
        pEmptyCat.Items.Add(DrivingResItem) 
 
        Dim EmbedmentItem As New PrintingItem("Embedment AFTER Scour (ft)") 
        EmbedmentItem.Values.Add(vLas1) 
        EmbedmentItem.Values.Add(vLas2) 
        EmbedmentItem.Values.Add(vLas3) 
        EmbedmentItem.Values.Add(vLas4) 
        EmbedmentItem.Values.Add(vLas5) 
        pEmptyCat.Items.Add(EmbedmentItem) 
 
        PlungingSection.Categories.Add(pEmptyCat) 
 
        Dim FrictionCat As New PrintingCategory("Friction") 
        Dim CapacityItem As New PrintingItem("Capacity (tons)") 
        CapacityItem.Values.Add(vFrictionCapacity1) 
        CapacityItem.Values.Add(vFrictionCapacity2) 
        CapacityItem.Values.Add(vFrictionCapacity3) 
        CapacityItem.Values.Add(vFrictionCapacity4) 
        CapacityItem.Values.Add(vFrictionCapacity5) 
        FrictionCat.Items.Add(CapacityItem) 
 
        Dim CritScourItem As New PrintingItem("Critical Scour (ft)") 
        CritScourItem.Values.Add(vFrictionCritScour1) 
        CritScourItem.Values.Add(vFrictionCritScour2) 
        CritScourItem.Values.Add(vFrictionCritScour3) 
        CritScourItem.Values.Add(vFrictionCritScour4) 
        CritScourItem.Values.Add(vFrictionCritScour5) 
        FrictionCat.Items.Add(CritScourItem) 
 
        Dim SafetyItem As New PrintingItem("Safety") 
        SafetyItem.Values.Add(vFrictionSafety1) 
        SafetyItem.Values.Add(vFrictionSafety2) 
        SafetyItem.Values.Add(vFrictionSafety3) 
        SafetyItem.Values.Add(vFrictionSafety4) 
        SafetyItem.Values.Add(vFrictionSafety5) 
        FrictionCat.Items.Add(SafetyItem) 
 
        PlungingSection.Categories.Add(FrictionCat) 
 
        Dim EndBearingCat As New PrintingCategory("End-Bearing") 
        Dim ebCapacityItem As New PrintingItem("Capacity (tons)") 
        ebCapacityItem.Values.Add(vEndBear1) 
        ebCapacityItem.Values.Add(vEndBear2) 
        ebCapacityItem.Values.Add(vEndBear3) 
        ebCapacityItem.Values.Add(vEndBear4) 
        ebCapacityItem.Values.Add(vEndBear5) 
        EndBearingCat.Items.Add(ebCapacityItem) 
 
        Dim ebCritScour As New PrintingItem("Critical Scour (ft)") 
        ebCritScour.Values.Add(vBearCritScour1) 
        ebCritScour.Values.Add(vBearCritScour2) 
332
        ebCritScour.Values.Add(vBearCritScour3) 
        ebCritScour.Values.Add(vBearCritScour4) 
        ebCritScour.Values.Add(vBearCritScour5) 
        EndBearingCat.Items.Add(ebCritScour) 
 
        Dim ebSafety As New PrintingItem("Safety") 
        ebSafety.Values.Add(vBearingSafety1) 
        ebSafety.Values.Add(vBearingSafety2) 
        ebSafety.Values.Add(vBearingSafety3) 
        ebSafety.Values.Add(vBearingSafety4) 
        ebSafety.Values.Add(vBearingSafety5) 
        EndBearingCat.Items.Add(ebSafety) 
 
        PlungingSection.Categories.Add(EndBearingCat) 
 
        Dim notesCat As New PrintingCategory("") 
        Dim adNotes As New PrintingItem("Additional Notes:", Notes) 
        notesCat.Items.Add(adNotes) 
 
        PlungingSection.Categories.Add(notesCat) 
 
        AllSections.Add(PlungingSection) 
 
        TimberPrinter.PrintSections(AllSections, header) 
 
    End Sub 
 
    Private Sub ExitButton_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles ExitButton.Click 
        End 
    End Sub 
End Class 
 
333