Many earthquake disaster experiences show that aftershocks may cause secondary damage to structures,which cannot be ignored.However,at present,the relevant codes at home and abroad have not clearly stipulated that the effects of aftershocks should be considered in the seismic design of structures.Therefore,in this paper,fragility is used as the structural seismic performance evaluation method,and aftershocks are included in the fragility analysis framework.The 40 real mainshock-aftershock sequences are selected as the seismic input of the structure,and the modified Park-Ang damage index is used to assess the seismic damage of the structure.Then,this paper evaluates the effect of aftershocks on structural fragility from two perspectives:1)The mainshock-aftershock sequence is regarded as an extended ground motion,which is directly used as the ground motion input of the structure,considering the intensity ratio of four mainshock-aftershocks(IMA/IMM,IM i.e.intensity measure),and seismic fragility analysis is performed by developing the probabilistic seismic demand model of the structure.2)Four mainshock damage states are defined.First,the mainshock are used as input to develop the mainshock damage structures,and then the aftershock fragility of the four states of mainshock damage structures was evaluated.The results show that aftershocks increase the fragility of the structure,when IMA/IMM=0.5～1.2,the median IMM of the structural fragility curve decreases by 2.6%～26.7%on average.When the damage index of the structure after the mainshock is 0.1～0.7,the ability to resist the subsequent aftershock collapse is reduced by 0.63%～22.6%.
关键词
主余震序列/地震易损性/修正的Park-Ang指数/主余震强度比/主震损伤状态
Key words
mainshock-aftershock sequences/collapse fragility/modified Park-Ang damage index/mainshock-aftershock strength ratios/mainshock damage states
维普
万方数据