Analysis of Bridge Response Considering Water-Soil-Pile-Structure Interaction under a Scoured Condition

Scour removes soil and reduces the capacity of a pile foundation, and thus may cause instability of a bridge. An analysis of bridge response under scoured conditions requires consideration of water-soil-pile-structure interaction. However, limited research has been done to integrate the analysis of water-soil-pile-structure interaction for a bridge due to scour. In this study, an attempt was made to consider such integration. A pile group was treated as an equivalent single pile, and the nonlinear response between soil and the equivalent single pile was modeled usingp-y The curve. influence of water flow was considered by applying stream pressure to the bridge piers and the pile foundation at different scour depths. Interaction between the piles and superstructure was analyzed by performing iterative calculations of their respective stiffness matrices until convergence was obtained. Kansas Bridge 45 was selected as a case study for evaluation of a typical scour-susceptible bridge under scoured conditions. The results show that scour significantly increased lateral deflection of the pile head. Considering pile cap had positive effects on the decrease of the lateral deflection of the pile groups. The investigation was also made into the influence of boundary conditions of bridge abutment on the lateral bridge responses.