Study on rocking response of base-isolated structure considering the tensile effect of isolators

Abstract

This paper carries out the parametric study of the rocking response of base-isolated structures by considering the tensile effect of isolation bearings. Experimental investigations are conducted to analyze the compression-shear and tension-shear behavior of lead rubber bearings (LRBs).The results reveal significant differences between the tension-shear and compression-shear behavior of LRBs. Building upon the experimental findings, the equations of motion for the base-isolated structure are established using the two-spring extension model proposed by Ryan and Chopra, with particular emphasis on incorporating the tensile effect of LRBs. Important parameters are selected based on practical engineering considerations within the governing equations. Nonlinear time-history analysis is performed to obtain numerical results, leading to the conclusion that the tensile effect of the isolation bearings should not be overlooked, especially for base-isolated structures with a slenderness ratio greater than 2. Furthermore, the number of isolation bearings also has a greater impact on the rocking response of base-isolated structures compared to the mechanical behavior of bearings. Finally, the paper analyzes the impact of variations in selected parameters and proposes the limiting values of slenderness ratios for base-isolated structures based on the requirements of the Chinese Standard for seismic isolation design of buildings (GB/T51408-2021).