The purpose of this study is to investigate the efficiency of various structural modeling schemes for evaluating seismic performances and fragility of the reactor containment building (RCB) structure in the advanced power reactor 1400 (APR1400) nuclear power plant (NPP). Four structural modeling schemes, i.e. lumped-mass stick model (LMSM), solid-based finite element model (Solid FEM), multi-layer shell model (MLSM), and beam-truss model (BTM), are developed to simulate the seismic behaviors of the containment structure. A full three-dimensional finite element model (full 3D FEM) is additionally constructed to verify the previous numerical models. A set of input ground motions with response spectra matching to the US NRC 1.60 design spectrum is generated to perform linear and nonlinear time-history analyses. Floor response spectra (FRS) and floor displacements are obtained at the different elevations of the structure since they are critical outputs for evaluating the seismic vulnerability of RCB and secondary components. The results show that the difference in seismic responses between linear and nonlinear analyses gets larger as an earthquake intensity increases. It is observed that the linear analysis underestimates floor displacements while it overestimates floor accelerations. Moreover, a systematic assessment of the capability and efficiency of each structural model is presented thoroughly. MLSM can be an alternative approach to a full 3D FEM, which is complicated in modeling and extremely time-consuming in dynamic analyses. Specifically, BTM is recommended as the optimal model for evaluating the nonlinear seismic performance of NPP structures. Thereafter, linear and nonlinear BTM are employed in a series of time-history analyses to develop fragility curves of RCB for different damage states. It is shown that the linear analysis underestimates the probability of damage of RCB at a given earthquake intensity when compared to the nonlinear analysis. The nonlinear analysis approach is highly suggested for assessing the vulnerability of NPP structures.

本研究的目的是研究用于评估先进动力堆 1400 (APR1400) 核电厂 (NPP) 中反应堆安全壳建筑 (RCB) 结构的抗震性能和脆弱性的各种结构建模方案的效率。开发了四种结构建模方案，即集中质量棒模型（LMSM）、固体有限元模型（Solid FEM）、多层壳模型（MLSM）和梁桁架模型（BTM），用于模拟地震。收容结构的行为。另外构建了一个完整的三维有限元模型（完整的 3D FEM）以验证先前的数值模型。生成一组响应谱与美国 NRC 1.60 设计谱匹配的输入地面运动，以执行线性和非线性时程分析。楼板响应谱 (FRS) 和楼板位移是在结构的不同高度处获得的，因为它们是评估 RCB 和次要组件地震易损性的关键输出。结果表明，随着地震烈度的增加，线性分析和非线性分析之间的地震响应差异变大。可以看出，线性分析低估了地板位移，而高估了地板加速度。此外，还对每个结构模型的能力和效率进行了系统的评估。MLSM 可以作为完整 3D FEM 的替代方法，后者建模复杂，动态分析极其耗时。具体而言，BTM 被推荐为评价核电厂结构非线性抗震性能的最佳模型。此后，线性和非线性 BTM 用于一系列时程分析，以开发不同损伤状态下 RCB 的脆性曲线。结果表明，与非线性分析相比，线性分析低估了给定地震强度下RCB的损坏概率。强烈建议使用非线性分析方法来评估核电厂结构的脆弱性。