DYNAMIC RESPONSE OF INELASTIC BUILDING- FOUNDATION SYSTEMS

This paper examines the importance of two-dimensional soil-structure interaction (SSI) on the dynamic response of inelastic building-foundation systems located on sites where SSI effects can be significant. The building is modeled as an elastic-plastic one-story structure, meant to represent the first translational modal response of actual buildings, resting on an embedded foundation. A parametric study is conducted to assess the effects of the various SSI parameters on the steady state seismic response. The focus of the study is on the ductility demands, inter-story drifts, inelastic dissipated energy, and total lateral displacements. The results show that SSI leads to significant changes in the dynamic response of SSI systems as compared to the associated fixed-base systems. Moreover, for inelastic systems it is observed that the peak value of the response, including SSI effects, can be greater than that for the corresponding fixed-base systems. Thus, contrary to current seismic provisions, neglecting SSI effects can lead to non-conservative results. This finding points to the need of incorporating SSI in the dynamic analysis to avoid inaccurate evaluation of the seismic response. Special attention should be paid to properly estimating the SSI parameters including factors such as layering, proximity to other structures, stiffness of the foundation members, and embedment