Seismic Performance of Building Frames Considering Soil–Structure Interaction

Abstract

It is a fact that response of the soil influences the motion of the structure and the motion of the structure in turn influences the response of the soil which is known as soil–structure interaction (SSI). The present study aims to evaluate the seismic performance of building frames considering SSI effect on scale-down steel building frame model prepared corresponding to RC prototype building frames of various height which are designated with reference to H/B ratio (H and B being height and width of building, respectively) as low-rise building for H/B less than 3.5, mid-rise building for H/B in between 3.5 and 5.25, and high-rise building for H/B higher than 5.25. The building frames considered are square in plan with single bay in both directions resting on GW soil. The experimental setup for fixed and flexible base condition is developed in the laboratory. The scaled-down models are subjected to El Centro time history using uniaxial servo hydraulic shake table. The effect of SSI on various dynamic parameters, i.e. acceleration, velocity, and displacement are studied. The study reveals that SSI effect is not significant in the low-rise building frame. However, with the increasing H/B ratio, SSI effect goes on becoming significant and predominant with nonlinear response. The study further reveals that mid-rise building frames is severely affected than high-rise building frame. In high-rise building frame, lower 30% portion is not affected by SSI. The middle 30% portion is producing almost same results for both the base condition. However, upper 40% portion of the building is significantly affected by SSI. Therefore, it is inferred that, not all, but certain building frames get affected by SSI depending upon their configuration such as H/D ratio and plan geometry apart from ground input motion (El Centro) supported on soil (GW) soil. Hence, it is recommended to incorporate SSI in the analysis of mid-rise and high-rise building frames to identify its vulnerability against safety and stability.