考虑主余震序列的高墩刚构桥地震易损性分析

Seismic Vulnerability Analysis of Continual Rigid-bridge with High Piers Considering Mainshock-aftershock Earthquake Sequences

基于主震和余震的统计关系以及多性能极限状态的相关性理论,提出了考虑主余震序列的桥梁系统地震易损性评估方法。该方法可以较全面地考虑余震对桥梁地震易损性分析的影响,同时又可避免用桥墩局部易损性代替系统易损性产生的较大误差。以一座典型双肢薄壁高墩高构桥为例,建立了其考虑余震作用的系统地震易损性曲线,并将结果与仅考虑主震作用的易损性曲线对比。结果表明:评估高墩刚构桥地震易损性时,宜考虑主余震序列,否则将高估其在各级地震下的抗震性能,此现象对严重损伤、完全破坏情形尤为明显;主震震级越大,余震对高墩刚构桥地震易损性影响越强烈;即使高墩刚构桥在主震中仅发生轻微损伤,但在余震中倒塌的可能性仍然很高。

Based on the statistical relationship of mainshocks and aftershocks and the multi-dimensional performance limit states theory,a new seismic vulnerability assessment methodology for whole bridge considering the influence of mainshock-aftershock earthquake sequences is proposed. The most striking feature of this method is that it can consider the influence of the aftershocks comprehensively in seismic fragility assessment and can eliminate the error resulting from substituting the pier vulnerability for system vulnerability.Compared with the curves only considering mainshocks sequence,the earthquake vulnerability curves considering mainshock-aftershock sequences are built for a rigid bridge with double-leg thin-walled high piers. The results show that the influences of mainshockaftershock earthquake sequences should be considered when assessing the seismic vulnerability of the bridge,otherwise the seismic performance could be overestimated. The above phenomenon for heavy or destroyed damage is more obvious. The greater the magnitude of a mainshock is,the stronger the influence of the aftershock becomes. The possibility that the rigid bridge collapsed in aftershock is still high even if it is damaged slightly in the mainshock.