Soil–structure Interaction and Vertical-horizontal Coupling Effects in Buildings Isolated by Friction Bearings

Abstract

Prior studies, which have been limited to horizontal ground shaking, have generally concluded that soil–structure interaction (SSI) has a negligible influence on the seismic response of isolated buildings. In this study, the effect of SSI on the response of a computational model of an isolated building using triple friction pendulum bearings is investigated. The analysis shows that SSI can amplify story drifts and accelerations when the model is subjected to 3-D shaking including a vertical component. Amplification occurs due to a vertical-horizontal coupling effect that is explained using the modal properties of the numerical model. Based on a parametric study using the key parameters of foundation system, it is concluded that amplification occurs when the effective shear wave velocity of the soil falls into a specific range. In this case, the response of the computational model is very sensitive to the hysteretic damping ratio of the soil, Poisson’s ratio of the soil and the footing size.