Derivation of the Governing Equation for Integral Abutment Bridges Considering Surrounding Soil-Structure Interaction Under Temperature Differential Thermal Stresses

In this study, retaining wall displacement is investigated using advanced lateral earth pressure coefficient formulations by deriving the governing equations for integral bridges, incorporating surrounding soil-structure interaction (SSI) under thermal stresses induced by temperature differentials. In integral bridges, displacements caused by secondary stresses—such as temperature variations, concrete shrinkage, and creep—are accommodated through soil-structure interaction; hence, this effect must be explicitly considered in the design of various bridge components. Daily and seasonal temperature fluctuations cause expansion and contraction of the bridge deck, inevitably exerting significant forces on abutments and piles. One viable approach to prevent thermal-induced structural damage and mitigate displacements in continuous concrete bridges is the numerical modeling of surrounding soil-structure interaction, an aspect that has received limited attention in recent years. By employing this approach, many of these design challenges can be overcome, particularly in continuous single-pier concrete bridges where rigid connections require more optimized/slender superstructure cross-sections. Therefore, the primary objective of this research is to develop an effective governing formulation capable of predicting soil behavior implemented in MATLAB. This formulation accounts for the lateral displacement of the retaining wall toward the surrounding foundation soil as well as the thermal cyclic response of the wall driven by temperature fluctuations over time. Consequently, particular focus is placed on the accurate calculation of the lateral earth pressure coefficient governing soil behavior. The direct contribution of this research is the derivation of the governing equation for integral abutment bridges with retaining walls, fully incorporating surrounding soil interaction against temperature-differential thermal stresses.