Research on reliability-based damage performance of base isolated structure

The seismic damage model of base isolated structure is proposed. The stochastic characteristics of damage index of base isolated structure are analyzed by the probability density evolution method. This work provides the basis for performance objective quantification of base isolated structure. The damage index model of the isolation story is proposed by considering the compression-shear correlation and tension-compression difference of isolators. The Park-Ang damage index is used to describe damage status of superstructure. The damage index model of base isolated structure is established. The simplified two masses calculating model of base isolated structure is established. The Bouc-Wen model is used to simulate the isolation layer and the stiffness degradation of Bouc-Wen model is used to simulate the superstructure. The state equation of base isolated structure is established. The displacement response and the hysteresis energy of base isolated structure are iterative solved by four-order Runge-Kutta method. As a result, the damage index of base isolated structure can be got. The probability density evolution equation of base isolated structure is established. The stochastic characteristics and probability density function of damage index are obtained. The reliabilities of damage index not exceed different performance levels are calculated by extreme value distribution theory. The reliabilities of base isolated structure impacted by different yield force ratios and period ratios are also analyzed. This study provides a reference method for performance based seismic design of base isolated structure on basis of reliability theory.