SEISMIC RESPONSE OF TORSIONALLY COUPLED STRUCTURE WITH ELASTOPLASTIC BASE-ISOLATION

An analysis of a one-storey model of a torsionally coupled base isolat ed building for two-component random ground motion is presented. The b ase isolator consists of an array of elastomeric bearings between the base of the building and its foundation. The hysteretic behaviour of i ndividual bearings is assumed to be elastoplastic. The response analys is considers the effect of the interaction between the restoring force s in the two principal directions on the yielding of the individual be arings. The response of the system is obtained under different paramet ric variations in order to investigate the effectiveness of base isola tion and the effect of force interaction during yielding of the bearin gs on the response. The effectiveness of base isolation is quantified with the help of the response ratio between the mean peak responses of the torsionally coupled system with and without base isolation. It wa s observed that the biaxial force-interaction during the yielding of t he bearings has considerable influence on the response.