Earthquake Loss Evaluation Of A Critical Building For Disaster Prevention Seismically Retrofitted By Different Seismic Damage Control Methods

The direct economic loss of buildings under seismic effect not only comes from the damage to structural components,but also comes from the damage to nonstructural components and building contents.For buildings which conform to the seismic design code,the direct economic loss is mainly caused by the damage to nonstructural components and building contents.Using the FEMA P-58 seismic performance assessment methodology,a critical building for disaster prevention,with insufficient seismic performance,is evaluated in this study.Three seismic retrofitting structures: base isolation,buckling restrained bracing and pin-supported wall are designed and building performance model is established to evaluate the impact of seismic response of different structural systems on the direct economic loss of buildings.The main research works are summarized as follows:1.Several seismic retrofitting design of a critical building for disaster prevention.The basic structural information of the building is introduced,the three-dimensional nonlinear finite element model of the structure is established,and the seismic performance of the structure is evaluated using the capacity spectrum method;Three seismic retrofitting structures: base isolation,buckling restrained bracing and pin-supported wall are designed.The seismic performance of buckling restrained bracing frame and pin-supported wall frame are evaluated by the capacity spectrum method,and the seismic performance of the isolation frame is evaluated by time history analysis.The reinforcement structure can meet the seismic fortification of 7 degree(0.15g).2.Building performance model of a critical building for disaster prevention is established.The building performance model includes basic building data,occupancy,fragility and performance groups,the amount,fragility parameters and consequence functions of building components.Fragility and performance groups are important parameters of the model.The fragility parameters of the structural components,nonstructural components and building contents(medical equipment,storage and file cabinet)mostly referred to fragility database of FEMA P-58,some referred to domestic research works.3.Analyzing seismic response and assessing the economic loss of the building.Considering the effect of infill wall,26 near field and 26 far field ground motion records are selected.Seismic response of the original structure and the reinforced structure is obtained by time history analysis.The result shows that the maximum story drift of the three seismically retrofitted structures can be effectively reduced comparing to the original structure,and the peak floor acceleration of isolation frame can be effectively reduced,while under the influence of near field ground motion records,the peak floor velocity of the upper structure of isolation frame may be larger than the original structure.4.The FEMA P-58 seismic performance assessment methodology is used to compare the economic loss of each structure under different ground motion intensities(Frequent,Fortification,Rare)of the 7 degree(0.15g)and Rare ground motion intensities of the 8 degree(0.20 g and 0.30g).The result shows that the loss of velocity sensitive components of base isolation structure takes most of the total loss,while acceleration sensitive components of other structures accounts for most of the total loss,and the loss of drift sensitive components of the three seismic retrofitting structure is less than the original one.The peak floor acceleration of the upper structure of isolation frame is smaller,thus the loss of the acceleration sensitive components is lower.As a result,the total loss of isolation frame is less than that of the other structure under different ground motion intensities.