Effect of soil-structure interaction on the seismic performance of structures designed by ASCE7-16
Performance-seismic design of structures aims to control earthquake damage through energy dissipation and the inelastic behavior of some structural elements based on the type of the structure. The current seismic design codes generally design for seismic effects by applying lateral static forces distributed over the height of the structure. The effect of soil structure interaction (SSI) is neglected in these codes. While not required, ASCE 7-16 does provide guidance on optional SSI as applied to equivalent lateral force, linear dynamic, and nonlinear dynamic procedures. Therefore, the current study investigated the seismic performance of a mid-rise multistory moment resisting frame (MRF) structure designed according ASCE 7-16. The effects of SSI have been examined where the structures designed with the classical way of fixed base for site condition class D and seismic hazard building risk category D. The models were analysed with a shallow foundation resting on soil with a shear wave velocity of Vs =250 m/sec and subjected to different seismic excitation. Fully nonlinear analysis was conducted using FLAC2D software with two different cases of ﬁxed-base and flexible base. SSI effect were investigated in terms of the elastic displacements which were observed to increase in general compared to the fixed base but that increase does not affect the life safety and does not lead to the collapse in terms of drift.