Soil-structure interaction effects on the seismic response of multistory frame structure

In this paper, soil-structure interaction effects on the seismic response of multistory frame structure on raft foundation are numerically analyzed. The foundation soil profile is assumed to consists of a clay layer of variable thickness resting on bedrock. A modified plane-strain numerical model is formed in the software Plaxis, and both free vibration analysis, and earthquake analysis for a selected ground motion accelerogram are performed. The behavior of the structure is assumed to be linear elastic with Rayleigh viscous damping included. The behavior of the clay layer is modeled with a Hardening soil model with small strain stiffness. The computed results in terms of fundamental period and structural horizontal displacements for the case of fixed base and for different thicknesses of clay layer are presented, compared, and discussed.