震损钢筋混凝土框架结构余震韧性分析

Aftershock resilience evaluation of mainshock-damaged reinforced concrete frame structures

针对震损结构的余震安全评估问题,提出一种与主震损伤状态相关的震损结构余震韧性评估方法,该方法将余震韧性评估划分为主余震序列选取、震损结构余震易损性分析、震损结构修复时间计算和恢复函数确定4个主要部分,其中选取主余震序列时同时考虑主、余震条件均值谱匹配;采用Logistic回归方法构建状态相关余震易损性函数;基于结构主余震累积损伤结果并参考GB/T 38591—2020《建筑抗震韧性评价标准》计算震损结构修复时间;根据灾后救援力量和社会应急能力,确定震损结构的恢复函数。为验证提出方法的合理性,对一栋钢筋混凝土框架结构进行算例分析,结果表明:随着主震损伤程度的加深,震损结构的余震经济损失显著提高、余震韧性水平明显下降;当主震损伤达到严重破坏状态时,震损结构的余震经济损失比完好结构增加10倍,震损结构的抗震韧性水平比完好结构下降41%;产生主震损伤后,结构抗余震能力呈现出非线性衰减特性,因此,对结构进行抗震韧性评估时有必要考虑当前的震损状态。

In order to evaluate the seismic resilience of a damaged structure for aftershock excitations,a framework of seismic resilience assessment for damaged structures,which was dependent on the mainshock damage states,was developed in this study.The framework was divided into four parts,namely,the selection of mainshock-aftershock sequences,aftershock fragility analysis,the computation of repair time and the determination of the recovery function.For the above-mentioned four parts,the conditional mean spectrum of mainshock and aftershock,the damage-dependent aftershock fragility function based on Logistic regression method,GB/T 38591—2020‘Standard for seismic resilience assessment of buildings’and the characteristic of social resources and rescue capacity were employed to solve the four issues.In order to verify the proposed framework,a seismic-designed RC frame was selected as the case example for the resilience evaluation.The results show that with the increasing of structural damage,the aftershock economic loss of the structure is obviously increasing,and the resilience of the damaged structure is significantly decreased.When the mainshock-induced damage reaches the severe damage state,the decrease rate of structural resilience can be up to 41%,and the increment of economic loss can be as much as 10 times of that of the undamaged structure.There is a nonlinear reduction for the seismic performance when the mainshock damage occurs.Therefore,it is necessary to account for the influence of the current structural damage state in the resilience assessment of a structure.