考虑设计标准差异及耐久性的老旧建筑结构地震易损性评估

SEISMIC VULNERABILITY ASSESSMENTS FOR OLD BUILDINGS BY DIFFERENT VERSIONS OF SEISMIC DESIGN CRITERIA AND DURABILITY

在目前的老旧钢筋混凝土框架结构的地震易损性研究中,没有同时考虑不同抗震设计标准差异和耐久性两个因素对结构抗震性能的影响,且表征结构易损性的损伤指数在阈值范围和动力分析中存在局限。有鉴于此,针对不同抗震设计标准造成的结构性能差异,同时考虑混凝土碳化和钢筋锈蚀对结构性能的影响,并根据结构已服役时间对老旧建筑结构的地震作用取值进行调整,构建了3个典型5层钢混框架结构建筑,建立相应的有限元模型并进行增量动力时程分析,采用弹塑性耗能差率和最大层间位移角表征结构损伤并进行地震易损性分析和对比。结果表明:随着抗震设计标准的提升,结构的设计抗震能力有较显著提高而易损性有一定的下降;同一结构的地震易损性因混凝土碳化作用先降低后增加。采用弹塑性耗能差率表征既有建筑结构的地震易损性效果优于最大层间位移角。

In the current study of seismic vulnerability of old reinforced concrete-frame structure,the influence of different seismic design criteria and durability on the a seismic performance of structure is not considered together,and the damage indicator which characterizes the structural vulnerability has limitations in the threshold range and dynamic analysis.Hence,considering differences of structural performances caused by concrete carbonization and rebar corrosion,based on different versions of seismic design criteria,the seismic action value according to structures service time was adjusted,three typical five-story steel-concrete frame structures were built.The corresponding finite element models were constructed and the incremental dynamic time-history analysis was conducted.The differential ratio of elastic plastic dissipated energy and the maximum interstory drift were used to characterize the structural damage,then the seismic vulnerability was analyzed and compared.The results showed that the a seismic capacity of the designed structure had been significantly improved and the vulnerability had decreased to a certain extent conducted by the updated seismic criteria.The seismic vulnerability of the same structure first decreased and then increased due to concrete carbonation.The differential ratio of elastic plastic dissipated energy was better than the maximum interstory drift to characterize the seismic vulnerability of existing structures.