Coupled soil-pile-structure interaction analysis under seismic excitation

Seismic soil-pile-structure interaction has been an area of limited research, and most of the existing work adopts the conventional approach of soil-structure interaction analyses in which the problem is solved by superposition of kinematic and inertial interaction. This multistep approach is often time consuming. The present study focuses on a coupled finite element-boundary element type approach, where the entire problem domain is solved in a single pass. The problem is cast in the frequency domain and a substructured method of analysis is adopted by interfacing the superstructure and the foundation at the foundation cap level. The free-field seismic response is calculated by an equivalent-linear method that is widely used. The formulation allows for multiple supports with varying excitations. Coupling of the problem allows one to construct transfer functions for various degrees of freedom in the structure including the effects of interaction. A number of examples presented in this paper demonstrate the utility of the method in solving problems involving bridge piers and building frames.