【摘要】 假定地震为平稳过滤高斯白噪声过程,基于隔震支座的等效动刚度和等效黏滞阻尼比建立了基础隔震结构的动力方程.针对动力方程中非经典阻尼的情况,采用状态空间理论和复模态叠加法对振动方程进行了解耦,推导了基础隔震体系上部结构和隔震层在随机地震动激励下的方差反应解析式.采用变形准则分别定义了上部结构和隔震层的极限状态,根据首次超越机制,并基于串联可靠度模型建立了隔震结构在给定地震动下的条件动力可靠度计算方法.通过一个基础隔震框架计算实例,说明了该方法的运用.在此基础上,分析了隔震支座等效动刚度和等效黏滞阻尼比对隔震结构随机反应和可靠度的影响,并以失效概率为优化目标,对隔震参数进行优化.该方法可以从整体上对隔震结构可靠性进行评估,为基于可靠度的隔震参数优化提供基础.更多还原

【Abstract】 The earthquake-induced ground motion is assumed to be zero mean valued stationary filtered Gaussian white noise process.The equation of motion of multi-degree of freedom structure with base isolation is represented by the state equation in state space according to the special situation that the damping matrix is not classical.In the state space,the complex mode superposition method is used to deduce the covariance responses of superstructure and isolation layer of base isolation system under excitation of random seismic ground motion.According to the deformation failure criterion,the limit states of superstructure and isolation layer are defined,respectively.The reliability model of the multi-story structure is considered as series connection model,the dynamic conditional failure probability of superstructure,isolation layer and base isolation structure are evaluated,respectively at given ground acceleration on the basis of the first passage mechanism.Then,a frame structure with base isolation is given as numerical example and the effect of equivalent dynamic stiffness and viscous damping ratio of isolation layer on the random response and dynamic reliability are analyzed,respectively.Considering the failure reliability as optimization objective,the parameters of isolation layer are optimized.This method can be applied to evaluate the overall performance of the base-isolation structure and can be a basis of reliability-based optimization for the seismic isolation structures.更多还原