Effect of Nonlinear SSI on Seismic Response of Low-Rise SMRF Buildings

Abstract

Nonlinear behavior of soil-foundation system may alter the seismic response of a structure by providing additional flexibility to the system and dissipating hysteretic energy at the soil-foundation interface. However, the current design practice is still reluctant to consider the nonlinearity of the soil-foundation system, primarily due to lack of reliable modeling techniques. This study is motivated toward evaluating the effect of nonlinear soil-structure interaction (SSI) on the seismic responses of low-rise steel moment-resisting frame (SMRF) structures. In order to achieve this, a Winkler-based approach is adopted, where the soil beneath the foundation is assumed to be a system of closely spaced, independent, nonlinear spring elements. Static pushover analysis and nonlinear dynamic analyses are performed on a 3-story SMRF building, and the performance of the structure is evaluated through a variety of force and displacement demand parameters. It is observed that incorporation of nonlinear SSI leads to increase in story displacement demand and reduction in base moment, base shear, and inter-story drift demands significantly, indicating the importance of its consideration toward achieving an economic yet safe seismic design procedure.