Displacement Prediction for Sloped Rolling-type Isolation Bearings under Different Seismic Demands

Displacement Prediction for Sloped Rolling-type Isolation Bearings under Different Seismic Demands

A sloped rolling-type isolation bearing features the constant transmitted horizontal acceleration performance owing to its sloped rolling surface design. In engineering practice, the constant acceleration level can be simply designed and predicted by the equation of motion. Nevertheless, for the bearings that possess zero post-elastic stiffness, the equivalent linear assumption might not be feasible for simply and conservatively designing and predicting the maximum isolation displacement. This study aims to statistically obtain some empirical equations for displacement prediction of the bearing. First, the derived analytical model is experimentally verified by using three bearings designed with different sloping angles. Then, a large amount of numerical analyses is performed to gather statistics of maximum isolation displacements of sloped rolling-type isolation bearings designed with different sloping angles and damping forces under varied seismic demands. For conservative purposes, the average value plus two-fold standard deviation is taken into consideration. The adopted seismic excitations are compatible to the design spectra specified in Taiwan Seismic Design Code for Buildings. Finally, some empirical displacement design equations are regressed and obtained, which will be very helpful for engineering practice.