摘要
一次强震过后通常伴有多次余震发生,由于主震和其后续余震之间的间隔时间较短,使得主震损伤结构未能得到及时修复而进一步遭受余震作用,产生“二次损伤”。山地结构的受力性能与普通结构有显著差别。参考我国现行规范设计了具有代表性的3个不同掉层数与掉跨数的山地掉层框架结构及1个普通平地框架结构,采用增量动力分析方法,以Park-Ang损伤指数作为结构响应参数DM,以PGA作为地震动强度参数IM,给出了掉层结构以及平地结构在主余震作用下的易损性曲线,对比分析了掉层结构与平地结构的易损性,研究了余震对各结构易损性的附加影响。基于抗倒塌储备系数(CMR)评价了结构的抗倒塌能力,比较了各结构的抗震倒塌安全储备。结果表明:余震会提高结构的超越概率,且随着余震强度的提高,超越概率越大;掉层结构的超越概率更高,且掉层数与掉跨数对结构地震易损性的影响较大;与平地结构相比,山地掉层结构抗倒塌储备系数较小,抗倒塌安全储备较低。对于掉层结构,掉跨数与掉层数的增加均会降低结构的抗倒塌安全储备,且掉层数对CMR的影响更大。
A strong earthquake commonly triggers the occurrence of multiple aftershocks.Three structures with different layers and crosses and an ordinary flat frame structure were designed with reference to the current codes of China.Based on the incremental dynamic analysis method,the Park-Ang damage index was adopted as the parameter of structural response,and the peak ground acceleration was used as the parameter of the ground motion intensity.Then,the vulnerability curves of the step-terrace structures and the ordinary flat frame structure under a mainshock and aftershocks were obtained.The vulnerabilities of the step-terrace structure and the ordinary flat frame structure were compared and analyzed,and the influence of aftershocks on the vulnerability of each structure was studied.The anti-collapse abilities of the structures were evaluated based on the collapse margin ratio(CMR),and the safety reserves of the structures were compared.The results show that the aftershocks increased the exceedance probability of the structure,and with the increase of the aftershock intensity,the exceedance probability was bigger.Compared with the ground structure,the exceedance probability of the step-terrace structure was higher,and the influence of the number of layers and the number of falling spans on the vulnerability of the structure was significant.Compared with the ordinary flat frame structure,the anti-collapse reserve coefficient of the step-terrace structure was small,and the anti-collapse safety reserve was lower.For the step-terrace structure,the increase in the number of layers will reduce the collapse of the security reserves,and the number of layers has a great impact on the CMR.
作者
杨佑发
肖淳
谭曦
YANG Youfa;XIAO Chun;TAN Xi(Key Laboratory of New Technology for Construction of Cities in Mountain Area of the Ministry of Education, Chongqing 400045, China;College of Civil Engineering, Chongqing University, Chongqing 400045, China)
出处
《地震工程学报》
CSCD
北大核心
2020年第2期290-298,共9页
China Earthquake Engineering Journal
基金
重庆市建设科技计划项目(2016-07)。
