基于新西兰实际震害资料的地震损失不确定性分析

Earthquake loss uncertainty based on detailed loss data in New Zealand

描述地震作用与工程破坏之间关系的易损性曲线及其概率分布对于地震灾害损失的可靠评估至关重要。以对数正态分布为主体的现行易损性概率分布模型无法很好地描述完好无损和完全破坏这2种边界条件。文中基于新西兰近40万栋房屋的历史震害信息,确认了这2种边界条件的存在,并对各种给定地震动水平下结构的损失分布进行了研究,提出了考虑上述2种边界条件的易损性混合概率分布模型,即首先单独考虑完好无损和完全破坏2种边界情况,然后再利用分布函数拟合其他的地震损失分布。通过对混合概率分布模型的损失分布与实际损失分布进行比较,验证了文中所提模型的有效性,可以用于未来分析地震损失的不确定性分布。

Earthquake vulnerability and its probability distribution in describing the relationship between earthquake excitation and engineering damage are important in reliable earthquake loss estimation.The current approach of mostly using lognormal distribution for the probability distribution cannot well explain the boundary conditions of no damage and total collapse.Based on the detailed loss data of close to 400000 buildings in many earthquakes of New Zealand,this paper verified the existence of the two boundary conditions and conducted extensive study on the loss distribution for various ground motion levels,and a mixed probability distribution model was proposed to better describe both the boundary conditions and the loss distribution between the two boundaries.Based on the loss data,the two boundary conditions were first estimated,then a distribution function was used to estimate the loss distribution between the two boundaries.The comparison of modeled loss distribution with the actual loss distribution validated the proposed model,thus better reliability of loss estimation should be expected when the new proposed model would be applied in the future.