主余震作用下典型六层RC框架结构易损性分析

Vulnerability analysis of typical six-story RC frame structure under mainshock-aftershock ground motions

摘要:

为研究RC框架结构在主余震作用下的易损性，以一典型六层RC框架结构为例，基于增量动力分析法和易损性分析，进行不同主余震作用下RC框架结构不同性能状态下超越概率的对比分析。选取10条满足场地条件的地震记录作为输入，分别以反应谱加速度为强度指标（IM）、最大层间位移角为损伤指标（DM）,对IDA曲线簇进行分位分析。依据地震强度指标建立概率地震需求模型，并根据已定义的结构性能水准对框架结构进行易损性分析。结果表明：双向地震和主余震作用相对于单向主震作用都会增加结构的易损性指数；结构在遭遇地震强度Sa(T1,5%)=0.5g时，余震造成易损性指数的上限值、平均值和下限值分别增幅6.3%、8.5%和11.5%；双向地震相对于单向地震造成易损性指数的上限值、平均值和下限值分别增幅15.5%、20.1%和32.5%。

Abstract:

In order to study the vulnerability of the RC frame structure under the action of mainshock-aftershocks, a typical six-story RC frame structure is taken as an example. Based on the incremental dynamic analysis and vulnerability analysis, the transcendental probability of the RC frame structure under different performance states under different mainshock-aftershocks effects is compared and analyzed. According to the site conditions, 10 seismic records have been selected as the seismic input, the response spectrum acceleration is used as the intensity measure (IM), and the maximum interlayer displacement angle is used as the damage measure (DM), respectively. The IDA curve cluster is analyzed by quantization. A probabilistic seismic demand model is established based on the seismic intensity measure, and the vulnerability analysis of the frame structure is performed according to the defined structural performance level. The results show that the bidirectional earthquake and the main-aftershocks will increase the vulnerability index of the structure compared with the one-way mainshocks. When the structure encounters an earthquake intensity Sa(T1,5%) =0.5g, the upper limit, average value, and lower limit of the vulnerability index caused by aftershocks increase by 6.3%, 8.5% and 11.5%, respectively. Compared with the one-way mainshocks, the increase of vulnerability index caused by two-way earthquake is 15.5%, 20.1% and 32.5%, respectively.