Reliability-based damage performance of base-isolated structures

The seismic damage model of base-isolated structures was proposed. The stochastic characteristics of damage index of base-isolated structures were analyzed with the probability density evolution method. This study provided a basis for performance objective quantification of base-isolated structures. The damage index model of the isolation story was proposed considering the compression-shear correlation and tension-compression difference of isolators. The Park-Ang damage index was used to describe damage status of the superstructure, then the damage index model of base-isolated structures was established, and the simplified two-mass calculation model of base-isolated structures was established. Bouc-Wen model was used to simulate the isolation layer and Bouc-Wen model with stiffness degradation was used to simulate the superstructure, and the state equation of base-isolated structures was established. The displacement response and the hysteretically dissipated energy of base-isolated structures were iteratively solved with the fourth-order Runge-Kutta method. As a result, the damage index of base-isolated structures then was solved. The probability density evolution equation of base-isolated structures was established. The stochastic characteristics and probability density function of the damage index were solved. The reliabilities of the damage index not exceeding different performance levels were calculated with the extreme value distribution theory. The reliabilities of base-isolated structures affected by different yield force ratios and period ratios were also analyzed. This study provided a reference method for performance-based aseismic design of base-isolated structures on basis of the reliability theory.