As the temperature of an integral bridge changes, the length of the bridge increases and decreases, so that the abutments are pushed against the approach fill and then pulled away, causing lateral deflections at the tops of the piles that support the bridge. As a result, complex interactions take place among the abutment, the approach fill, the foundation soil, and the piles supporting integral bridges. Finite element analyses were performed to investigate these complex interactions. The results of this study indicate that these interactions have a beneficial effect on the stresses in the piles supporting the bridges. Because of these interactions, the foundation soil acts as if it were softer, resulting in reduced shear and moment in the piles at a given amount of deflection at the tops of the piles and therefore reduced stresses in the piles.