EVALUATION OF EQUIVALENT LINEAR-ANALYSIS METHODS OF BRIDGE ISOLATION

Various equivalent linear analysis methods for base-isolated regular b ridges are compared and evaluated in this paper. The equivalent linear analysis models encompassed in the paper are those specified by Assoc iation of State Highway and Transportation Officials (AASHTO) and the Japanese Public the American Works Research Institute (JPWRI). In addi tion, an internally used model by the California Department of Transpo rtation (CALTRANS) and a recently proposed model are also included, Th e comparison and evaluation are conducted to investigate the fidelity of various equivalent linear models in simulating the bilinear hystere tic bearings and the accuracy of the models in predicting the maximum seismic responses of the bearings. To perform the evaluation, a single degree of freedom (SDOF) system composed of a rigid block isolated by bilinear hysteretic bearings iis subjected to 55 earthquake ground mo tions. The discrepancies of maximum seismic responses predicted by equ ivalent linear;analysis methods and by inelastic analysis method are m easured using root mean square (RMS) errors. The average bf RMS errors over the 55 earthquake ground motions are compared and used to evalua te the formulations of equivalent linear analysis methods.