DISSIPATION OF HYSTERETIC ENERGY IN BASE-ISOLATED STRUCTURE

Dissipation of hysteretic energy in the isolator of the base isolated structure under seismic excitation is investigated. The hysteretic for ce-deformation characteristics of the base isolator is specified by no nlinear differential equation. The parameters of the equation can be a djusted to obtain various types of hysteretic models of the isolator i ncluding the elastoplastic type. The variation of hysteretic energy di ssipated in the isolators is obtained for both harmonic and El-Centro 1940 earthquake ground motion for a set of important parameters. They include time period of superstructure, ratio of superstructure mass to base mass, level of yield strength of the isolator, post- to preyield ing stiffness ratio, and the ratio of harmonic excitation frequency to base isolation frequency. It is shown that the dissipation of hystere tic energy in the isolator is significantly influenced by the above pa rameters. (C) 1996 John Wiley & Sons, Inc.