基于概率密度演化理论的地震概率安全评估

Seismic Probabilistic Safety Assessment Based on Probability Density Evolution Method

基于概率密度演化理论,通过引入随机地震动模型,可以获得某一场地在一定时期内遭遇不同地震动强度的超越概率,并且有望解决地震易损性分析中如何选择地震动的关键问题.在此基础上,通过调幅随机地震动模型的基底幅值参数,并与地震易损性研究中的增量调幅思想相结合,可以获得工程结构在遭遇不同超越概率的地震作用时,结构性能达到各极限状态的超越概率.这一将地震易损性曲线的地震动强度度量指标赋予概率意义的工作,可以避免以往采用不同地震动强度度量指标时,由于计算方法的不同,生成的地震易损性曲线具有较大不同的缺点.这一工作,进一步与基于性能的地震工程全概率决策框架相结合,可为工程结构的地震概率安全评估提供坚实的理论基础.

By introducing the stochastic ground motion model based on the probability density evolution method,the exceedance probability of engineering structures at different peak ground acceleration in a certain site and period can be assessed and presented,and the key problem of selecting the ground motion in seismic fragility assessment can be solved.Furthermore,when the structures encounter the earthquake ground motion in a different exceedance probability,the basal amplitude parameter of the stochastic ground motion model will be increased to calculate the failure probability of engineering structures at each limit state,which is consistent to the increment dynamic analysis of the seismic fragility analysis.The research that assigns the probability to the measurement of the ground motion intensity for the seismic fragility curves avoids the difference between the different methodologies used in the seismic fragility analysis. The proposed methodology should integrate with the total probability decision framework of performance-based earthquake engineering to provide a solid theoretical foundation for the seismic probabilistic safety assessment of engineering structures.