Numerically Modeling Structural Behavior of Precast Three-Sided Arch Bridges for Analysis and Design

Abstract

Foley Products contracted with Auburn University to perform laboratory testing and design validation of three-sided bottomless precast concrete structures being produced. Tests performed included a field test on an active construction project, a laboratory test of a 20 ft clear span structure, and a laboratory test of a 36 ft clear span structure. The field test was performed in Midland, North Carolina on a 42 ft clear span arch structure. The field test was a service load level test performed by backfilling around the structure and driving a truck with a known weight over the bridge and stopping at various locations. The 20 ft clear span and 36 ft clear span laboratory tests were performed in the Auburn University Structural Research Laboratory. Gauges were installed in these structures prior to casting so data could be collected during testing. In both laboratory tests the structures were loaded to failure using hydraulic loading actuators. Following testing, the computer program SAP2000 was used to develop two structural models. SAP2000 structural models of the 20 ft clear span structure as well as the 36 ft clear span structure was developed to correlate results between the structural analysis performed in SAP2000 and the data and results found during laboratory testing. Nonlinear behavior was accounted for in analysis. Moment hinges were incorporated in the structural model to correlate deflection magnitude in analysis to deflection measurements in the laboratory testing. iii Once the SAP2000 structural models were developed and correlated well with the laboratory test results, an evaluation of the design methodology in use by the designers of the Foley Arch was carried out. A structural computer model was developed in RISA 3-D by the designers and used in design of the structure to predict the point of maximum moment. The RISA 3-D model used in design of the Foley Arch was compared to the model developed in SAP2000 to evaluate how well the structure corresponded to the behavior the designers expected. It was found that the strength of the structures was adequate and that the design methodology being used was reasonable and safe.