Seismic Response of Structures with Underground Stories Considering Non-Linear Soil-Structure Interaction

Most of the research conducted for soil-structure interaction analysis of structures are assuming the linear behavior of soil. It is well known that during strong ground excitations the soil adjacent to the structure behaves highly non-linear. The nonlinear soil behavior affects the soil-structure interaction in a complex way especially because of the inadequacy in modeling the unbounded soil medium. In the case where an elastic soil behavior is assumed, the surface motion will be amplified proportionally to the input motion. However, in reality the amplitude and frequency content of the response are modified due to the soil’s stiffness degradation and higher energy dissipation. The present work deals with the influence of soil non-linearity, introduced by hysteretic behavior of near-field soil, on the soil-foundation-structure interaction phenomena. The objective is to reveal the beneficial or detrimental effects of the non-linear SSI concerning both the drift and settlement of structures with underground stories. To examine the effect of non-linear soil-structure interaction a realistic non-linear soil model is incorporated into the finite difference FLAC software. To better understanding the non-linear dynamic SSI, interface elements are also used between the near-field soil and basement walls. For a practical structure throughout a parametric study, some non-linear seismic analyses are performed to demonstrate the effectiveness of the affecting parameters in response of the structure. The results showed much difference on seismic response of structure such as drift, settlement and developing pressure around the basement walls when the non-linear soil-structure interaction is considered