层间隔震结构的随机地震反应与失效概率分析

Stochastic Seismic Response and Failure Probability of Story Isolation Structure

建立了层间隔震结构的动力分析模型,采用低频模拟和高频模拟方法相结合的综合功率谱模型模拟地震地面运动功率谱,运用虚拟激励法进行层间隔震结构的随机地震反应进行了分析,得到了隔震层及其他各层层间响应峰值的统计量。以隔震层和其他各层最大层间位移作为控制指标,建立极限状态方程,采用一次二阶矩方法,用MATLAB编程计算其失效概率,并用串联模式计算体系的整体失效概率。以江苏省高烈度区宿迁市的某20层的框剪结构为例,利用上述方法计算了层间隔震结构的位移随机响应和整体失效概率,并与非隔震结构进行了比较。结果表明,层间隔震结构上部各层失效概率较非隔震结构大大减小,且各层失效概率分布比较稳定。隔震结构整体的失效概率要远小于非隔震结构,层间隔震结构的动力可靠度显著增加。

The dynamic analytic model of story isolation structure is established.The seismic ground motion is assumed to be a hybrid model combining low frequency simulation and high frequency simulation,in order to reflect the frequency spectrum characteristics of seismic ground motion.Pseudo excitation method is used to calculate the stochastic seismic response of story isolation structure.The statistical quantity of the maximum story displacement of each layer is also obtained.The maximum story displacements of isolation layer and other layers are adopted as the performance index to establish the performance equation.The failure probability is calculated using first-order reliability method by MATLAB. The total reliability of structure is derived by regarding the stories to be of series relation.A 20-story frame shear-wall structure in high intensity zone in Suqian city is taken as an example.Stochastic seismic displacement responses and failure probabilities of isolated and non-isolated structure are compared.The results show that the superstructure＇s failure probability of the isolated structure is much smaller,and each layer＇s failure probability is well distributed.The failure probability of story isolation structure is much smaller than nonisolated structure.So the dynamic reliability of story isolation structure is increased rapidly.