Preliminary analysis of influence of soil models on seismic response of soil-structure interaction system

The soil is usually simplified as an elastic half space model and its influence is replaced by springs and dashpot elements, which is the most common method for soil-structure interaction(SSI) problem. The computation parameters of spring and dashpot elements are determined by soil impedance functions. But this is not the case in practical engineering because soil is not always a half space. Focusing on this problem, the aim of the paper is to study the influence of different soil modes on seismic response of soil-structure interaction system. Three kinds of soil models are considered, which are elastic half space model, stratum-over-rigid model and stratum-over- half-space model. The influence of different models on impedance functions are analyzed qualitatively firstly based on the formulas. Then the natural frequency, structure acceleration response and response spectra of structure acceleration are computed and analyzed by two specific cases. It is showed from the calculation results that the static stiffness impedance values from three models have some differences, but the dynamic stiffness impedance values are almost the same, and hence the influence of different soil models on system natural frequency and seismic response are not significant. The research results can provide references to the preliminary seismic design of soil-structure dynamic interaction system. ©, 2014, Academia Sinica. All right reserved.