Effect of Substructure Stiffness on Performance of Steel Integral Abutment Bridges under Thermal Loads

This paper presents a study that investigated the effect of substructure stiffness on the performance of short- and medium-length steel integral abutment bridges (IABs) built on clay under thermal load effects. Various parameters, such as pile size and orientation, pile type, and foundation soil stiffness, were considered in the study. Detailed, three-dimensional (3-D), finite element (FE) models were developed to capture the behavior of IABs. Field measurements from a IAB were used to validate the 3-D FE model developed with LUSAS software. With the use of validated models, a parametric study was carried out to study the effect of these parameters on the performance of IABs under thermal loading with AASHTO load and resistance factor design temperature ranges. The study showed that the substructure stiffness had a significant effect on the stress level induced by thermal loads in various components of the substructure and superstructure. The results also showed significant variations in displacement and stress between interior and exterior locations in relatively wide IABs. The study showed that prestressed concrete piles could form a viable alternative to steel H-piles for short-span bridges. The stress level from thermal loading in the various components of the bridge could be reduced significantly if the top part of the pile were placed in an enclosure filled with crushed stone or loose sand.