Prediction of Demands on Non-Structural Components in Base-Isolated Structures

Abstract

This study examines seismic demands imposed on non-structural components within base isolated structures. Although several previous studies have focussed on the ability of base isolators to limit structural damage, very few have predicted their influence on the demands imposed on acceleration-sensitive non-structural components. Hence, the motivation of this study is to progress towards an improved design philosophy for non-structural components located within base-isolated structures. The dynamic response of base-isolated structures is studied using simple two-degree-of-freedom models that describe the motion of the isolator and the superstructure. Bilinear hysteretic models are used to represent the behaviour of flat slider and elastomeric bearing isolators, while the superstructure is assumed to remain elastic. The results of the numerical simulations are used to relate isolator, superstructure, and ground motion characteristics to the observed floor response spectra. Special consideration is given to higher mode responses, which can produce significant demands on non-structural elements. The results will inform a prediction approach that is in development that aims to be more accurate than current international non-structural design practices, without compromising on simplicity, thus facilitating its adoption in practical design applications.