SIMPLIFIED NONLINEAR DYNAMIC ANALYSIS OF BASE-ISOLATED BUILDINGS SUBJECTED TO GENERAL PLANE MOTION

Considers hysteretic non-linear models for modelling horizontal force- displacement characteristics of an isolation system subjected to gener al plane motion. Simple close form solution of the stiff differential equation of hysteretic model for forces mobilized in the non-linear el ements of the base isolation system are obtained. Simulates experiment al shear force-displacement loops obtained from the hi-axial tests by different investigators. Both the experimental and the simulated hyste resis loops are found to be in good agreement. Develops a unified solu tion algorithm for computation of response of different types of base isolated buildings, considering non-linear behaviour of the isolation systems, subjected to multidirectional motion. The solution algorithm is based on the implicit-implicit partitioned Newmark's method in pred ictor-corrector form. Response of the base isolated symmetrical buildi ng as obtained from the solution algorithm and the computer programs d eveloped are in good agreement with that obtained from the more comple x numerical studies reported in the literature. Response of a three st oreyed symmetrical building isolated by pure friction isolators and la minated rubber bearings has been obtained using this simple yet accura te solution algorithm.