ABSTRACT

This paper presents a Bayesian-estimation-based seismic fragility assessment method that can significantly reduce the computational burden. The likelihood function and prior distribution used in the Bayesian estimation were enhanced. A probability density function of the seismic capacity was adopted as the likelihood function, although previous studies have generally used the fragility curve. Further, the prior distribution was assumed based on the seismic capacity obtained by incremental dynamic analysis. A sophisticated parametric study was additionally conducted, and we obtained information on the unknown parameters of the prior distribution to establish the initial values. Preliminary investigations show that these enhancements reduced the required number of seismic simulations to approximately 1/5 of that of the conventional Bayesian method. Then, the method was applied to a reinforced-concrete water intake system, which is a critical component of the core-cooling system in nuclear power plants (NPPs). The results revealed that the fragility curves determined using the proposed method with 12 repetitions of the simulations were comparable to those using a detailed method developed by the Atomic Energy Society of Japan with 500 repeated simulations. Therefore, we concluded that the proposed method could be applied to high-fidelity structures to substantially reduce the computational burden.

摘要

本文提出了一种基于贝叶斯估计的地震易损性评估方法，可以显着减少计算负担。贝叶斯估计中使用的似然函数和先验分布得到了增强。地震能力的概率密度函数被用作似然函数，尽管以前的研究通常使用脆性曲线。此外，先验分布是基于增量动力分析获得的抗震能力假设的。此外还进行了一项复杂的参数研究，我们获得了关于先验分布的未知参数的信息以建立初始值。初步调查表明，这些改进将所需的地震模拟次数减少到传统贝叶斯方法的大约 1/5。然后，将该方法应用于钢筋混凝土取水系统，该系统是核电厂 (NPP) 堆芯冷却系统的关键部件。结果表明，使用 12 次重复模拟的建议方法确定的脆性曲线与使用日本原子能学会开发的详细方法 500 次重复模拟的脆性曲线相当。因此，我们得出结论，所提出的方法可以应用于高保真结构，以大大减少计算负担。结果表明，使用 12 次重复模拟的建议方法确定的脆性曲线与使用日本原子能学会开发的详细方法 500 次重复模拟的脆性曲线相当。因此，我们得出结论，所提出的方法可以应用于高保真结构，以大大减少计算负担。结果表明，使用 12 次重复模拟的建议方法确定的脆性曲线与使用日本原子能学会开发的详细方法 500 次重复模拟的脆性曲线相当。因此，我们得出结论，所提出的方法可以应用于高保真结构，以大大减少计算负担。