Self-centring capacity of seismic isolation systems

The ability of seismic isolators to develop restoring forces, also referred as self-centring capacity, is commonly associated with the system ability to prevent excessively large unit deformations and possible isolator failure. This concept is emphasized in some of the current standards or guide specifications for the design of seismic isolated structures that usually impose minimum values of the isolator restoring force capacity. In this paper a numerical study is performed to investigate the influence of the parameters that characterize the model of a structure-isolator system on its self-centring capacity. The system is idealized as a rigid mass mounted on a single isolator in which a bilinear force-displacement relation, which approximates the nearly bilinear behaviour exhibited by most of the currently available devices, characterizes the isolator response. Results from this study provide insights on the merit of current guide specifications and on the overall isolation behaviour of the models. Copyright (C) 2006 John Wiley & Sons, Ltd.