Performance-based Direct Economic Loss Estimation For Buildings In High Seismic Hazard Areas Of China

The post-earthquake investigations and analyses of several large earthquakes have pointed out that the direct economic loss induced by structural damage are very large. The second generation of performance-based earthquake engineering ("second PBEE") using probability method has been developed by Pacific Earthquake Engineering Research Center (PEER) for the sake of guiding earthquake risk decision and reducing further earthquake loss. This paper estimated the expected direct economic losses of reinforced concrete frames in 0.3g seismic zone and 0.4g seismic zone and tested the economic loss rationality of buildings designed according to Chinese building codes in high earthquake hazard areas with performance-based economic loss assessment methodology. The research work below has been conducted in this paper. Peak ground accelerationâ‘ Peak Ground Acceleration (PGA) are selected as the earthquake Intensity Mesure IM. Earthquake hazard, that is, annual mean exceeding probability of peak ground acceleration, of Baotou (0.3g) and Kunming (0.4g) has been provided by Mengtan Gao.â‘¡Reinforced concrete office buildings in 0.3g seismic zone and 0.4g seismic zone have been designed in accordance with the lowest line of Code for Seismic Design of Buildings (GB50010-2002) and Code for Design of Concrete Structures (GB50011-2001). The acceleration records of earthquake ground motion have been selected by double-frequency-ranges method. The variation of Engineering Demand Parameter EDP when IM changes, that is, P(EDP│IM) has been obtained by using OpenSees simulation platform and Incremental Dynanmic Analysis (IDA) method. P(EDP│IM) is assumed to fit to lognormal distribution. The medians and logarithmic standard deviations of EDPs as IM changes have been estimated by the modified maximum likelihood method.â‘¢The probabilities that components'damage states are i conditioned on EDPs has been computed by using existed fragility functions of components.â‘£Component costs are computed from the Chinese current material and labor costs. Through multiplying the normalized expected loss of component j conditioned on a damage state i when the collapse has not occurred and the probability that DS is equal to dsi conditioned on EDP when the building has not collapsed, the expected normalized loss of component j conditioned on EDP when the building has not collapsed has been obtained. Then, the expected normalized loss of component j conditioned on IM when the building has not collapsed has been gained by multiplying expected loss of component j conditioned on EDP when the building has not collapsed and the probability that EDP_j is larger than edpj conditioned on IM when the collapse has not occurred. The expected loss of a building which has not collapsed conditioned on IM has been estimated by suming the expected losses of components conditioned on IM. The collapse probability conditioned on IM has been estimated. The expected economic loss of a building conditioned on IM has also been obtained. Finally, annual expected losses of buildings are computed by intergrating expected economic loss of a building conditioned on IM and annual mean exceeding probability of IM. The economic loss rationality of buildings designed according to Chinese building codes in high earthquake hazard areas has been assessed preliminarily.Through the foregoing analyses, the following conclusions have been gained.â‘ Generally, the median of EDP increases as IM accretes. However, IDR4 of 0.3g seismic zone declines when IM is larger than 35 m/s₂, IDR4 and IDR6 of 0.4g seismic zone decline when IMs are larger than 80 m/s₂ and 60 m/s₂ respectively. It is demonstrated that the value of EDP will no longer increases when IM reaches a certain value. The increasement of logarithmic standard deviations of EDP is small when IM accrecets.â‘¡The variation of percentage of chord rotation of column to interstorey drift ratio is apparent as storey changes. The percentage of chord rotation of column to interstorey drift ratio at bottom storey is comparably small; the percentage of chord rotation of column to interstorey drift ratio at top storey is comparably large. The percentage of chord rotation of column to interstorey drift ratio increases as earthquake ground motion intensity rises.â‘¢Non-structural components weight more than structural components in building costs. The loss of non-structural components is also larger than that of structural components. For structural components, when building in 0.3g seismic zone has not collapsed, the expected losses of structural components at 1^st, 2^nd and 3^rd storey conditioned on IM are comparably large, especially that of the 3^rd one; the expected losses of structural components at 4^th, 5^th and 6^th storey conditioned on IM are comparably small. For structural components, when building in 0.4g seismic zone has not collapsed, the expected losses of structural components at 1^st, 2^nd and 6^th storey conditioned on IM are comparably large, especially that of the 6^th one; the expected losses of structural components at 3^rd, 4^th, and 5^th storey conditioned on IM are comparably small. For non-structural components, the expected losses of components at 2^nd, 3^rd and 4^th under major earthquake intensity are larger than that of the other three storeys. The components with exorbitant loss can be strengthened when the building is re-designed.â‘£The structures reach the condition of collapse when the largest interstorey drift ratio of all storeys is equal to 0.1.⑤The economic losses ratio of reinforced concrete frame buildings in 0.3g seismic zone and 0.4g seismic zone, designed strictly according to Chinese building codes, when IMs are minor earthquake level, moderate earthquake level and major earthquake level, are similar. At minor earthquake level, the percent is about 1.5%; at moderate earthquake level, the percent is around 10%; at major earthquake level, the percent is approximately 20%. The loss situations of the buildings at the two cities are generally tolerable.â‘¥Annual economic loss of the building at Baotao is half of that of the building at Kunming (Dongchuan). The main reason is probaly that the annual mean exceeding probability of peak ground acceleration of Kunming (Dongchuan) is larger than that of Baotou in most earthquake intensity. The annual loss results can be used to compare with the annual profits of the buildings or annual earthquake insurances. The expected annual losses of the two buildings are relatively small. Under normal operation, the losses are greatly smaller than annual profits, which proof the validity of building design on the performance index of direct economic loss.