Field Behavior of Integral Abutment Bridges under Thermal Loading

Integral abutment bridges (IABs) have become popular with departments of transportation throughout the United States due to their lower maintenance and construction costs and longer service life. Nevertheless, IAB design and construction vary widely across the country, and not all aspects of IAB behavior are fully understood. Research has previously been conducted on IABs, but primarily with a focus on substructure behavior. However, recent studies have shown that IAB superstructures may develop significant stresses, which warrant consideration in their design. The work reported herein addresses the need to better understand not only IAB substructure behavior but also superstructure behavior, with a goal of improving design and construction provisions for IABs. Two bridges were instrumented, with primary focus on superstructure behavior and more limited instrumentation of the substructure. Corresponding finite-element models were developed based on modeling techniques and findings from prior parametric studies. It was found that the IAB decks and girders (in the superstructure) and abutments and piles (in the substructure) generally show seasonal and even daily trends with respect to changes in temperature, with the exception of bottom-flange girder stresses that have wider variability not directly related to temperature change. Prior modeling assumptions regarding the rigidity of various IAB connections were also validated through the field monitoring data.