Evidence of Combined Site Effects and Foundatıon-Soil-Structure Interaction Effects on Seismic Response of Rc Buildings

Abstract

The seismic excitation experienced by structures is a function of earthquake source effects, travel path effects, local site effects, and soil-structure interaction (SSI) effects. SSI effects related to variation of the structural behavior recently became a common practice in structural seismic design. Building seismic codes usually consider site effects through site factors, which reflect amplification of seismic waves due to the change in the geological contrast. For seismic structural analysis purposes, however, they consider the assumption of a fixed base, where, the input motion at the base of the structure is taken as equal to the free field ground motion. This paper investigates, in a rational way, the influence of kinematic and inertial SSI effects combined to local soil conditions effects on RC multistory buildings, resting on different design sites, through a global explicit transfer function for lateral component of the response. It comes from the combination of the transfer functions of structure, foundation and soil. It was found that the approach allows capturing the realistic physical fluctuations of the rock input motion before it excites the superstructure.