The Fragility And Economic Loss Estimation Of RC Frame Structure Subjected To Mainshock-aftershock Sequences

According to historical statistics,there will be different levels of aftershocks after the happening of mainshock.A lot of researchers have done much work on the structural reaction and fragility analysis of mainshock.In fact,structures have been caused some damage after suffering the mainshock.While experiencing aftershocks,the damage will be more severe.Looking back at the strong earthquakes,they caused considerable economic and casualties.Up to now,a series of achievements have been obtained in economic losses,but there is still less research on the estimation of casualties.Therefore,it is very important to consider mainshock-aftershock sequences and the casualties on the estimation of earthquake risks and economic losses.This paper focuses on the reaction analysis and fragility analysis of RC frame structure subjected to mainshock-aftershock sequences,and then eatimating the economic losses.Specific contents are as follows:(1)294 mainshock-aftershock sequences are selected.A finite element model of a typical six-story RC fame structure has been established by Open Sees.Then the maximum roof drift,residual roof drift,maximum interstory drift ratio,residual interstory drift ratio and the improved Park-Ang damage index have been studied under the mainshock-aftershock sequences.It is found that interstory drift ratio and the improved Park-Ang damage index are increased under aftershock..(2)The maximum interstory drift ratio and the improved Park-Ang damage index are selected as the structural damage index.After the incremental dynamic analysis,fragility curves of structure subjected to mainshock-aftershock sequences can be obtained.When the intensity of aftershock is 0.5-1.0 times of the mainshock,it is found that aftershock will increase the fragility of structure in the levels of 5%-40%.(3)Structural economic losses subjected to mainshock-aftershock sequences are analyzed.The direct economic losses,indirect economic losses and casualty losses are calculated respectly,then the total economic losses can be derived.The differences between mainshock-aftershock sequences and long-duration ground motions are evaluated.It is found that aftershocks can increase economic losses by10%-50%,and as the intensity of earthquake increases,casualty losses become lager than structural economic losses.