Seismic response of base-isolated buildings under near-field and far-field earthquakes considering SSI

Abstract

A numerical analysis is conducted to study the seismic response of a base-isolated building frame considering soil-structure interaction (SSI) under the influence of far-field and near-field earthquakes. A twenty-story building frame with lead rubber bearing as the base isolation (BI) system and a set of seven earthquake records was chosen for the study. The effect of SSI is incorporated by taking into account four distinct soil types: very soft, soft, medium, and dense. Further, four different combinations of bases (i.e., fixed base with/without SSI and BI with/without SSI) are considered to study, and the seismic responses of the building with these combinations are compared. The study focuses on roof acceleration and base-isolation layer displacement as the key response parameters. The numerical results indicate that the seismic responses of base-isolated buildings considering SSI are considerably higher under the effect of near-field earthquakes. In addition, the inclusion of SSI in base-isolated building reduces its effectiveness in terms of roof acceleration reduction in softer soil conditions under both near-field and far-field ground motions; however, the BI system works efficiently in building in terms of isolator displacement, especially in softer soil conditions under near-field earthquakes.