Effect of soil–bridge interaction on the magnitude of internal forces in integral abutment bridge components due to live load effects

Abstract

In this study, the effect of soil–bridge interaction on the magnitude of the internal forces in integral abutment bridge (IAB) components due to live load effects is studied. For this purpose, structural models of typical IABs are built by including and excluding the effect of backfill and foundation soil. Analyses of the models are then conducted under an AASHTO live load. In the analyses, the effects of the backfill and foundation soil on the magnitude of the internal forces in IAB components are studied for various structural, geometric and geotechnical parameters such as bridge size, abutment height and thickness, pile size and orientation, number of spans and foundation soil stiffness. The analysis results revealed that soil–bridge interaction has a significant effect on the magnitude of the live load moments in the components of IABs. Including the effect of backfill behind the abutments in the structural model is generally found to result in larger superstructure support and abutment moments and smaller superstructure span and pile moments. The difference between the live load moments for the cases with and without soil–bridge interaction effects is found to be a function of the foundation soil stiffness. However, the soil–bridge interaction is found to have only a negligible effect on live load shear in the superstructure. Furthermore, the equivalent cantilever concept used for modeling of the abutment piles is found to inconsistently yield either conservative or unconservative estimates of the internal forces in the components of IABs except for the superstructure shear.