Finite element analysis of pile-soil-structure dynamic interaction in liquefiable site

Based on Biot’s dynamic coupled theory for two-phase porous media, the earthquake response analysis for pile foundations was dealt with by a three-dimensional effective stress finite element method. Liquefiable saturated sand was simulated by a cyclic elasto-plastic constitutive model, which was mainly composed of overconsolidation boundary surface, Armstrong-Frederick type nonlinear kinematic hardening rule and non-associated flow rule, to describe the response features under seismic loading, such as cyclic mobility, liquefaction strength and so on. For the dynamic behaviour of piles, a beam-column element was used for considering the axial force-dependency as well as the volume effect. Subsequently, with the proposed method, an actual urban elevated highway bridge was illustrated involving a group-pile foundation subjected to seismic excitation in the saturated liquefiable deposits. From the simulated result, some fundamental aspects of pile-soil-structure dynamic interaction in liquefiable site were investigated to yield useful results for design.