|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
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.
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.