| The past earthquakes have shown that the their occurrence is often along with the mainshock,aftershock,and earthquake sequence.The engineering structures are damaged during the main-shock,while they can be further damaged by following aftershock,which may lead to the whole collapse of structure,inducing severe casualty and economic loss.The consideration of seismic performance assessment of structure during two successive earthquakes is not only the basis for seismic performance assessment of structure during main-shock and aftershock,but also the basis for assessment of cumulative damage of structure.How to select appropriate seismic performance measure is the focus and challenge for damage assessment of structure during two successive earthquake.For reinforced concrete frame structure considered in the paper,the new damage measure is used for damage analysis,and the economic loss,casualty,and unsafe placard are assessed during earthquakes.The main study is as follows:(1)The Ebrahimian damage measure model and modified Park-Ang damage measure model are introduced first,in which important parameters are determined in order to compare the damage assessment of structure during two successive earthquakes by using those two damage models,thus the analysis and assessment of seismic performance of structure are conducted.The new generation seismic performance assessment of building methodology,FEMA P-58,is introduced to evaluate the economic loss,casualty and unsafe placard of structure using Performance Assessment Calculation Tool(PACT)proposed in FEMA P-58,and thus the seismic performance assessment of structure is also conducted.(2)The six-storey reinforced concrete frame structure is designed based on structure design software the PKPM according to the current design standard of building structures.The structure is modeled by the finite element analysis software the Open Sees and nonlinear dynamic time history analysis of structure is conducted.The six different work conditions are considered,in which single earthquakes consist of moderate earthquake and severe earthquake,and two successive earthquakes are composed of moderate-moderate earthquake,moderate-severe earthquake,severemoderate earthquake severe-severe earthquake.The two damage models considered above are applied to evaluate damage condition of structure under those work conditions.The results show that there are several advantages such as the fewer parameters needed to identify and easy calculation in Ebrahimian damage measure model.The change trend of the whole damage level of structure calculated by this model is consistent with that of the modified Park-Ang damage measure model,which indicates the whole damage level of structure can be described by the Ebrahimian damage model.Compared to single earthquake,the cumulative damage of reinforce concrete during two successive earthquakes is obvious with increasing damage level.(3)The seismic performance of reinforced concrete frame structure is conducted during single and two successive earthquakes based on earthquake loss assessment theory of buildings of the PEER.The seven different work conditions are considered,in which single earthquakes consist of moderate earthquake and severe earthquake,and two successive earthquakes are composed of moderate-small earthquake,moderatemoderate earthquake,moderate-severe earthquake,severe-small earthquake,severemoderate earthquake and severe-severe earthquake.The performance measures,including repair time,repair cost,casualty,and unsafe placard of structure during earthquakes,are evaluated using the PACT proposed in the FEMA P-58.The results show that cumulative damage level of structure is obvious during two successive earthquakes,particularly in the severe-severe earthquake work condition,the unsafe placard probability of structure increases by 99.851%. |
