结构抗倒塌易损性分析中地震动输入不确定性影响研究  

THE IMPACT OF GROUND MOTION INPUTS ON THE UNCERTAINTY OF STRUCTURAL COLLAPSE FRAGILITY

作　　者：任叶飞[1] 尹建华 温瑞智[1] 冀昆[1] REN Ye-fei;YIN Jian-hua;WEN Rui-zhi;JI Kun(Institute of Engineering Mechanics,China Earthquake Administration,Key Laboratory of Earthquake Engineering and Engineering Vibration,China Earthquake Administration,Harbin 150080,China)

机构地区：[1]中国地震局工程力学研究所中国地震局地震工程与工程振动重点实验室

出　　处：《工程力学》2020年第1期115-125,共11页Engineering Mechanics

基　　金：国家重点研发计划项目(2017YFC1500801);国家自然科学基金项目(51778589,51878632);黑龙江省自然科学基金项目(E2017065);山东省高校土木结构防灾减灾协同创新中心基金项目(XTZ201901)

摘　　要：在结构抗倒塌易损性分析中地震动输入的选取只是众多环节之一,其不确定性影响往往被忽视。该文基于 PEER 强震动记录数据库,按震级、距离和场地参数(M、R、VS30)进行单变量控制将强震动记录分成 9 组,新定义指数 ISa 用以比较不同分组地震动的相对能量差异;对 3 层、8 层以及 15 层三种不同自振周期的混凝土框架结构采用 IDA 方法进行抗倒塌易损性分析,比较不同 M、R、VS30工况地震动输入下的易损性结果,同时与 ATC63推荐记录作为地震动输入的易损性结果进行了对比,结果表明:3 种结构的倒塌性态点 Sa(T1)均随着 M 增大、R增大以及 VS30 变小而减小;三种结构都体现了在大震、远场及软土场地的地震动作用下更加易损倒塌,与 ISa 指数体现的地震动蕴含能量的分布相一致;通过 SI 和 SImax 两个参数在不同工况下的对比,表明中长周期结构受距离的影响更为显著,以及震级对结构抗倒塌影响更敏感;以 ATC63 推荐的强震动记录随意用作地震输入被证实可引起结构抗倒塌易损性曲线较大的不确定性。为降低不确定性影响,建议在进行结构抗倒塌易损性分析时采用考虑场址危险一致性与结构自振特性的地震动输入选取方法。The selection of ground motion input is one of the key procedures in the analysis of structural collapse fragility,but its impact on the uncertainty is usually ignored.The strong motion records from PEER database are divided into 9 groups by constraining the range of a single variable,which is one of the earthquake magnitude,distance and site parameters(M,R,VS30).A new index Sa I is proposed to evaluate the difference of the relative energy of different groups of strong motion records.Incremental dynamic analysis(IDA)is conducted to analyze the collapse fragilities of three concrete frame structures,which are 3-floor,8-floor and 15-floor with different natural periods,respectively.The fragilities derived from each group of the ground motion inputs are compared.They are also compared with the fragilities when the 22 records recommended by ATC63 are used as the ground motion inputs.The results show that the ground motion intensity representing the occurrence of collapse performance Sa(T1)decreases with the increase of earthquake magnitude,increase of epicentral distance and decrease of VS30,irrespective of the structures of concern.All three structures are more vulnerable to collapse if the strong-motion records at a far-field soft site in a large earthquake are selected as the seismic inputs, which isapproximately consistent with the distribution of the relative energy of the ground motions represented by Sa I .The comparisons of the two parameters SI and SImax among the different groups indicate that there is a relativelyhigh sensitivity of epicentral distance for long-period structures, and the structural collapse fragility is moresensitive to the earthquake magnitude than to either the distance or the site condition. It is confirmed that a largeuncertainty of the structural collapse fragility will be produced if the 22 records recommended by ATC63 are usedas the ground motion inputs. For the sake of decreasing the uncertainty, it is suggested to use a method which canconsider the seismic hazard of the site and

关 键 词：强震动记录 地震动输入 结构抗倒塌易损性 不确定性 增量动力分析方法 

分 类 号：P315.9[天文地球—地震学]