Simple Approach to Calculate Displacements and Rotations in Integral Abutment Bridges

This paper presents a simple approach to calculate the displacements and the rotations induced by thermal loading in integral abutment bridges (IABs). The approach was derived from the results of a parametric study that investigated the effect of substructure stiffness on the performance of short- and medium-length steel IABs built on clay and sand under thermal load effects. Various parameters, such as pile size and orientation, pile material, and foundation soil stiffness, were considered in the study. Detailed three-dimensional (3-D) finite element (FE) models using the software LUSAS were developed to capture the overall behavior of IABs. The developed 3-D FE model was calibrated with field measurements obtained from a previous study. A parametric study was carried out with the calibrated models to study the effects of the above parameters on the performance of IABs under thermal loading using the AASHTO load and resistance factor design temperature ranges. The study showed that most parameters have significant effects on the displacement and rotation of the abutment and the supporting piles. Also, for relatively wide IABs, there were significant variations in the displacement and rotations in the substructure elements between interior and exterior locations. This approach, which used simple equations and charts and included parameters such as the length of the bridge, the stiffness of the foundation soil, and the pile location, provided results that were comparable with those of a detailed FE analysis.