Three-dimensional finite element modelling for seismic response analysis of pile-supported bridges

Soil-structure interaction (SSI) is involved in the pile-supported structures. Such effect is mainly accounted for soil-pile interaction (SPI) driven by the deformation of pile and surrounding soil, and thus it can become significantly obvious due to large soil deformation during a severe earthquake. To capture this characteristic of simply supported bridge structure with pile foundations, a three-dimensional (3D) finite element (FE) model is developed using the computational platform OpenSees considering SPI. A two-span reinforced concrete bridge with a single pier located in multi-layered clay is employed as a test-bed. A variety of seismic responses of this coupled soil-pile-bridge system are systematically investigated. Furthermore, a parametric study is performed to explore the influences of SPI, multidirectional excitation and earthquake characteristic on the seismic responses of soil and structure. The results show that: (1) the seismic response of the bridge structure is significantly affected by its longitudinal and transversal different configuration; (2) the fixed-base support type noticeably influences the seismic response of bridge structure and (3) the direction and characteristic of base input earthquake motion greatly influence the seismic response of the bridge-soil system.