考虑余震丛集特征的RC框架结构震后时变风险分析OA

Major earthquakes are often followed by numerous aftershocks.Aftershocks typically occur in clusters within a short interval,forming"aftershock clusters".Due to the short interval between the mainshock and aftershock clusters,the mainshock-damaged structures have little time to be repaired.As a result,their seismic performance exhibits significant time-varying characteristics during the aftershock period.To assess post-earthquake risk of mainshock-damaged structures,a time-dependent post-earthquake risk analysis method considering aftershock cluster characteristics was proposed.The time-dependent post-earthquake risk analysis was decomposed into two components:aftershock seismicity analysis and damage-state-dependent aftershock fragility analysis,and the time-dependent post-earthquake risk probability was derived by incorporating the Markov process.To validate the proposed method,the Long Men Mountain Fault region within the China Seismic Experimental Site was selected as the target region.A typical four-story reinforced concrete frame structure was used as the case-study structure.The daily variation in seismic risk under the effect of aftershock clusters was computed considering a one-year aftershock period following an M8.0 mainshock.Furthermore,the time-dependent risk was relative to the time-invariant risk obtained by considering only one maximum-magnitude aftershock.The results demonstrate that the proposed method could demonstrate the impact of aftershock clusters on post-earthquake risk and the impact is most significant within the first month after the mainshock.The exceedance probability of the time-dependent post-earthquake risk considering aftershock clusters increases over time,reaching up to 3.6 times that of the seismic risk considering only the maximum-magnitude aftershock,demonstrating that aftershock clusters substantially amplify on post-earthquake risk.It is necessary to consider aftershock cluster characteristics in post-earthquake risk analysis of structures.