Influence of Site Class on the Dynamic Response of Regular Buildings Considering Soil-Structure Interaction

Abstract

Throughout history, many buildings have suffered significant damage during major earthquakes. Traditionally, such damage has been extensively analyzed from a structural perspective, assuming a fixed-base condition as a valid approach for lightweight structures built on relatively stiff soil. Under these assumptions, various failure patterns have been identified. However, earthquake damage indicates that a structure’s seismic performance is not only influenced by the superstructure’s response but also by the behavior of the foundation and the underlying soil. This highlights the importance of considering soil–structure interaction (SSI), as the overall performance of a structure can be affected by the earthquake’s characteristics, its propagation path, and the nonlinear behavior of the soil. The soil–structure interaction (SSI) phenomenon is inherently complex; it involves a modification of the incident ground motion due to the dynamic response of the structure. As a result, the motion at the soil–structure interface differs from the free ground motion. This study aims to demonstrate the influence of soil–structure interaction on the behavior of regular mixed structures (frames with shear walls). The response of the structure studied is first evaluated by considering the hypothesis of perfect base fixity (classical model). In the second model (soil–structure interaction model), the soil–structure coupling is taken into account by modeling the soil reaction using springs. Numerical simulations were performed using four types of response spectra corresponding to different site classes, as defined by the Algerian seismic code (RPA 2003).