Investigating the effects of inelastic soil–foundation interface response on the seismic demand of soil–structure systems

Abstract

The effect of inelastic response of the soil–foundation interface is explored on the seismic demand of structures attached on top of shallow foundations. An ensemble of 20 strong ground motions recorded on National Earthquake Hazards Reduction Program site class D was employed for analyzing soil–structure systems with the Winkler foundation model and an equivalent single-degree-of-freedom system as the superstructure. Results show that there are key parameters that control the amount of difference between the elastic and inelastic modeling of the soil at the soil–foundation interface. Depending on the structural aspect ratio, the elastic modeling leads to an overestimated result for the total lateral displacement demands. Also, more than 50% reduction in the superstructure demands is desired when nonlinear soil modeling is considered and foundation sliding is allowed. The benefits from the “shrinking-dominated rocking motion” can be acquired with inelastic soil material that limits the transferred inertial force into the superstructure.