为了准确评估结构地震损伤,首先对能力谱法进行改进,考虑高阶模态及动力特性改变对结构地震反应的影响,采用基于能量准则的能力谱和弹塑性需求谱计算结构最大顶点位移。其次,推导多自由度体系(MDOF)与等效单自由度(ESDOF)体系的滞回耗能转化关系,利用多模态ESDOF体系的概念评估结构滞回耗能需求。在此基础上,同时引入结构地震变形与滞回耗能,改进模态往复pushover分析方法(MMCP),采用隐式双参数模型评估结构地震损伤。将该方法应用于两个三层钢筋混凝土框架,结果表明:MMCP分析在一定程度上模拟了地震作用,在精确的结构地震位移和滞洄耗能评估基础上,能够准确地预测结构整体和层间损伤。MMCP法还可以与设计反应谱相联系,使评估结果具有一定的普遍性和安全度。
In order to better assess the structural seismic damage,some improvements were made for the CSM(capacity spectrum method).The contributions of the high modals and the variable dynamic characteristics to the structural responses were considered,and an energy-based capacity spectrum and the inelastic demand spectrum were introduced to obtain the maximum roof deformation.The hysteresis energy relationship between the multi-DOF(MDOF) system and the equivalent single-DOF(ESDOF) system was deduced,and the multi-modal ESDOF method was incorporated to calculate the hysteretic energy demand of the structures.Based on the maximum deformation and the hysteretic energy,a modified modal cyclic pushover(MMCP) method was elaborated to evaluate the seismic damage with an implicit damage index.The method was applied for two three-storey reinforced concrete frames.The results indicate that,to some extent,the MMCP analysis may simulate the seismic action.Based on the accurate assessment of the deformation and the hysteretic energy of the structures,the real damage status of both the entire structure and the different stories may be determined.In addition,the MMCP method can also be associated with the design response spectrum,for the evaluation results to be reliable and safe.