考虑非结构构件损伤的钢筋混凝土框架建筑多维地震易损性分析

基于单一指标的传统地震易损性分析忽略了非结构构件损伤对建筑抗震性能的影响。首先基于多维性能极限状态理论建立了三维性能极限状态方程,并对几种特殊情况下的三维阈值曲面进行了讨论。进而以最大层间位移角作为整体结构与位移敏感型非结构构件的性能指标,以峰值楼面加速度作为加速度敏感型非结构构件的性能指标,对建筑的结构损伤和非结构损伤进行描述。考虑各性能指标之间的相关性和各性能指标所对应的极限状态阈值的不确定性,建立了建筑在地震作用下的三维性能极限状态的超越概率函数。最后,采用Open Sees有限元软件对一7层钢筋混凝土框架填充墙建筑进行增量动力分析,得到其各性能水平下的地震易损性曲线。分析结果表明,当忽略非结构构件损伤时,各性能极限状态的超越概率均降低,从而高估了建筑剩余功能水平,进而导致低估建筑的损失。在考虑各性能指标的极限状态阈值的不确定性时,对任一性能极限状态,不同变异系数取值下的易损性曲线会出现交点,在交点之前超越概率随着变异系数的增大而增大,交点之后则随着变异系数的增大而减小。在考虑性能指标间的相关性时,对任一性能极限状态,超越概率随着相关系数的减小而增大。另外,性能指标阈值的不确定性与性能指标间的相关性对地震易损性的影响随着性能水平的提高而逐渐降低,且对低性能水平下建筑地震易损性有明显影响。

Multi-dimensional seismic fragility analysis of reinforced concrete framed building considering damage of non-structural components

The traditional seismic fragility analysis based on single index ignores the influence of damage of nonstructural components on building performance. First,the three-dimensional performance limit state equation was established based on the multi-dimensional performance limit state theory,and several different threshold surface shapes were discussed. Then,maximum interstory drift ratio was taken as the performance index for the overall structure and the displacement-sensitive non-structural components,and the peak floor acceleration was taken as the performance index for the acceleration-sensitive non-structural components to describe both the structural and non-structural damage of buildings. The correlation between various performance indices and the uncertainty of the limit state threshold corresponding to each performance index were further considered to derive the exceedance probability function of the three-dimensional performance limit state of the building under ground motion. Finally,a 7-storey reinforced concrete framed building was modelled numerically via OpenSees software to perform incremental dynamic analysis( IDA). And the seismic fragility curves of the building corresponding to various performance levels were obtained. The analytical results show that when the damage of non-structural components is neglected,the exceeding probability corresponding to each performance level decreases thus the residual function level of the building would be overestimated and the loss would be underestimated. When the uncertainty of the limit state threshold of performance index is considered,the fragility curves with different coefficients of variation will intersect for any performance limit state. The exceedance probability increases with the increase of coefficient of variation before the intersection point,and decreases with the increase of coefficient of variation after the intersection point.When the correlation between performance indicators is considered,for any performance limit state,the seismic fragility curve of buildings shifts to the left with the decrease of correlation coefficient,which increases the probability of building exceedance. In addition,the influence of uncertainty of the threshold of the performance index and the correlation between performance indicators on seismic fragility decreases with the increase of performance level,and this kind of influence is more obvious for low performance level.