主余震作用下防屈曲支撑框架结构联合易损性分析

Joint vulnerability analysis of buckling-restrained braced frame under mainshock-aftershock sequences

针对防屈曲支撑在主余震作用下可能发生疲劳破坏,引起其所在楼层刚度发生突变,导致结构倒塌的问题,对考虑支撑疲劳性能的防屈曲支撑框架,采用峰值层间位移角和残余峰值层间位移角作为联合指标,进行增量动力分析和地震易损性分析。结果表明,主余震作用下防屈曲支撑框架的抗倒塌能力明显降低,且随着地震作用的增加,结构易损性概率显著加大。此外,通过分段积分的方式确定了2种指标对结构易损性概率的影响,结果表明,结构性能受结构残余变形影响较大。因此,在进行防屈曲支撑框架设计时有必要考虑主余震组合作用对防屈曲支撑疲劳和变形的影响,对其性能提出更高要求。

The buckling-restrained braces may undergo fatigue failure under the action of the mainshock-aftershock sequences,which can lead to a sudden change of the stiffness and structural collapse.In this study,for a buckling-restrained braced frame with the consideration of its fatigue characteristics,the peak interstory drift and the residual peak interstory drift were jointed to perform incremental dynamic analysis and vulnerability analysis.The results showed that the collapse capacity of the structure was significantly reduced under the action of the mainshock-aftershock.With the increase of the earthquake action,the probability of structural failure was significantly increased.In addition,the influence of the two jointed indexes on the vulnerability of the structural structure was determined by means of segmented integration.It was found that the structural performance was mainly affected by the residual drift.Therefore,it was necessary to consider the influence of the mainshock-aftershock on the fatigue and deformation of the brace in the design process,and to have higher demands on its performance.