IDENTIFICATION OF DYNAMIC PROPERTIES OF ISOLATED STRUCTURES

This paper develops an identification scheme to investigate the dynami c behaviour of isolated structures in which laminated rubber bearings are used, A linear model is used for the superstructure while a biline ar hysteretic model is chosen for the isolation system, The modal para meters of the superstructure are estimated on the basis of an iterativ e identification algorithm and are employed to identify the parameter values of the isolation system, The essence of this study is the appli cation of the Masing criterion by which hysteretic loops of bearings m ay be characterized through the skeleton curve, The multivalue restori ng force is then transformed into a single-value function so that the ordinary identification process can be carried out with only minimal c omputational effort beyond that required for the identification of a l inear system, Numerical examples include the four-storey Foothill Comm unities Law and Justice Center in California and show the feasibility of the proposed technique for identifying the hysteretic isolation sys tem.