MODELING OF ISOLATION BEARINGS FOR THEIR NONLINEAR BEHAVIOUR

Abstract

In this thesis, the isolators are modeled for their nonlinear behaviour. The force-displacement relationship of typical elastomeric bearings is nonlinear as a result of their inherent damping properties. Therefore, the accurate prediction of the seismic behaviour of base isolated structures depends on the accuracy of the mathematical model of the non-linear mechanical properties of the isolation bearings. Consequently there are many models that have been used to model the isolation bearings in order to evaluate the seismic response of the base isolated buildings. But the simplest and the convenient model is the bilinear model. This model has been adopted in this study and the seismic response of the base isolated building with various isolation systems have been evaluated for harmonic excitations and for Northridge N-S earthquake component. To check for the accuracy of the equivalent linearisation procedure the results obtained from the bilinear model, i.e., effective stiffness and effective damping have been used in the linear model. The results of the equivalent linearisation procedure show the accuracy in predicting the various quantities of interest. The results of the bilinear model show the capability of this model in predicting the response of the base isolated building. The performances of the isolation systems have been discussed