Soil-Structure Interaction Effects on Seismic Response of Multi-storey Buildings

The effect of soil-structure interaction (SSI) on the seismic responses of multi-storey buildings is investigated. The execution of SSI effects is conducted in two ways viz. Winkler approach and soil continuum approach. Time-history analysis methods are used for the seismic evaluation of parameters like time period, modal mass participation, base shear, lateral displacement, storey drift and inter-storey drift ratio. The present study consists of two parts; one is fixed base analysis i.e. without SSI, and the other is flexible base analysis i.e. with SSI. The buildings are modelled using finite element-based software SAP2000, where the equilibrium equations are solved by Hilber-Hughes-Taylor (HHT) method. A parametric study is performed with existing ground motion and varying numbers of stories to inherit the above parameters' responses. The results obtained from flexible base conditions are compared to those corresponding to fixed base conditions. The study shows that the behaviour of the structure changes under the SSI conditions and it may become vital in some cases; however, ambiguity also subsists with SSI.