A design approach for semi-active and smart base-isolated buildings

Abstract

Hybrid isolation systems consisting of mainly a base isolation system and either active controllers or semi-active dampers or smart dampers or combination thereof for protecting buildings from seismic damage can make further improvements on isolation performance. The control forces in active controllers of hybrid isolation systems are analyzed and the damping characteristics of control forces in active controllers are then observed. Two indices are defined to quantify the damping characteristics of control force in active controllers. Based on the observation of damping characteristics of control forces in active controllers, a design approach for semi-active, smart and even passive dampers in a hybrid isolation system is presented. For comparative design purposes, the average value of maximum control forces in active controllers and control devices to be designed for several excitation records are assumed to be the same, i.e. the control design is normalization. A five-storey building and the smart base-isolated benchmark building are employed as numerical studies. The simulation results demonstrate that smart base isolation systems designed by using the proposed design approach can achieve almost the same performance as an active base isolation system in protecting the safety of buildings against strong earthquakes. Additionally, active controllers or semi-active controllers in hybrid base isolation system present the behavior of passive devices. And thus passive devices in base isolation systems can be instead of active controllers or semi-active controllers with the performance of the base isolation system remaining. Copyright © 2005 John Wiley & Sons, Ltd.