Fragility Analysis And Economic Loss Estimation Of RC Frame Structure Suffering Damage From Earthquake And Subsequent Tsunami

Tsunami hazard tends to occur near the southeast coastal seismic belt at a small probability in China.Many of the most economically developed cities are located in coastal regions,which are highly likely to experience substantial ground shaking from an offshore earthquake that precedes a tsunami and then experience the tsunami forces themselves,resulting in fatalities and catastrophic damage to communities.The design codes of China do not consider the impact of subsequent disasters.According to post-earthquake investigations,structures suffered damage from earthquake can be severely destroyed or even collapsed under tsunami loading.Therefore,setting up a basic approach to numerically consider the successive seismic and tsunami risk to buildings,as well as to further assess the total loss of buildings,is of great significance.This paper focuses on the response,fragility analysis as well as economic losses estimation of RC frame subjected to sequential earthquake and tsunamis.Specific contents are as follows:(1)Building up the methodology of nonlinear structural analysis of RC buildings suffering from earthquake and subsequent tsunami.In the case of earthquake,dynamic structural response analysis is performed to predict damage of RC buildings,which are subjected to earthquake ground motions.Sequentially,static structural analysis is performed to predict more damage to RC buildings,which are subject to hydrodynamic force from tsunami.Typical RC fame structures have been established by Open Sees as case study for the investigation.The structural response affected by earthquake intensity,flow inundation depth,flow velocity and structure opening rate are analyzed.(2)Based on the incremental dynamic analysis,the joint fragility analysis of the structure under earthquake and subsequent tsunami is done.It takes flow depth and flow velocity as tsunami intensity measures and spectrum acceleration as earthquake intensity measures.The maximum interstory drift ratio is selected as engineering demand parameters.The results show that as the flow velocity or flow depth increases,the collapse probability increases.When the 4-story structure is subjected to 2m tsunami,it’s found that the collapse probability increased by 11.7%.Besides,the lower portion of the fragility curve is the earthquake sensitive section.(3)Structural losses subjected to earthquake and tsunami in sequence are analyzed via PACT under the guidance of FEMA P-58.It offers a probability-based loss assessment method,which takes the uncertainty of structural members and nonstructural members into consideration.The loss assessment is investigated for structure subjected to earthquake only and sequential earthquake and tsunami,which shows great difference in repair costs,repair time,and casualty losses.