Funding information European Comission, Horizon 2020 program, Grant/Award Number: 691213; Presidenza del Consiglio dei Ministri – Dipartimento della Protezione Civile, ReLUIS program Summary In seismic risk assessment of structures, fragility functions are the probabilistic characterization of vulnerability at the component and/or structural level, expressing the probability of failure as a function of a ground motion intensity measure (IM). Fragility curves, in general, are structureand site-specific, thus a comparison of fragility curves, then of vulnerability, is not straightforward across multiple structures. Also, it could be the case that hazard at a site of interest is not available for the IM originally considered in the fragility assessment. These situations require to convert fragility curves from an original IM to a target one. The present study addresses a hazard-consistent probabilistic framework for converting spectral acceleration-based IMs from an original IM to a target IM at a given site. In particular, three conversion cases, under different assumptions on the explanatory power of the involved IMs with respect to structural failure, are discussed: (a) a vector-valued IM consisting of the original and target IMs, magnitude, and source-to-site distance; (b) a vector-valued IM consisting of the original and target IMs; and (c) the original (scalar) IM only, assuming that structural response, given the IM, is statistically independent of the other ground motion variables. In this framework, the original fragility functions are characterized using the state-of-the-art methods in performance-based earthquake engineering, then the fragility curves as a function of the target IM are evaluated through applications of the probability calculus rules, ensuring consistency with the seismic hazard at the site of interest. The conversion strategy is illustrated through the applications to three-, six-, and nine-story Italian code-conforming reinforced concrete buildings designed for a high-hazard site in Italy. The study shows that, in most of the cases, the converted fragility curves have agreement with the reference curves directly developed in terms of the target IM. Cases in which least agreement was found are likely due to the models used to obtain the terms required by the conversion equations.

中文翻译：

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脆性曲线的强度测量转换

资金信息欧洲委员会，地平线 2020 计划，赠款/奖励编号：691213；Presidenza del Consiglio dei Ministri – Dipartimento della Protezione Civile，ReLUIS 计划摘要在结构的地震风险评估中，脆弱性函数是部件和/或结构级别脆弱性的概率特征，将失效概率表示为地面运动的函数强度测量（IM）。一般而言，脆性曲线是结构和地点特定的，因此在多个结构之间比较脆性曲线和脆弱性并不简单。此外，也可能是在脆弱性评估中​​最初考虑的 IM 无法获得感兴趣地点的危害。这些情况需要将脆性曲线从原始 IM 转换为目标曲线。本研究解决了一个危险一致的概率框架，用于将基于谱加速度的 IM 从原始 IM 转换为给定站点的目标 IM。特别地，讨论了三种转换情况，在不同假设下涉及的 IM 对结构故障的解释能力：（a）向量值 IM 由原始和目标 IM、幅度和源到 -场地距离；(b) 由原始和目标 IM 组成的向量值 IM；(c) 仅原始（标量）IM，假设给定 IM 的结构响应在统计上独立于其他地面运动变量。在这个框架中，使用基于性能的地震工程中最先进的方法来表征原始脆弱性函数，然后通过应用概率演算规则评估作为目标 IM 函数的脆性曲线，确保与感兴趣地​​点的地震危险性一致。通过对为意大利高危场所设计的符合意大利规范的三层、六层和九层钢筋混凝土建筑的应用来说明转换策略。研究表明，在大多数情况下，转换的脆性曲线与根据目标 IM 直接开发的参考曲线一致。发现最不一致性的情况可能是由于用于获得转换方程所需项的模型。通过对为意大利高危场所设计的符合意大利规范的三层、六层和九层钢筋混凝土建筑的应用来说明转换策略。研究表明，在大多数情况下，转换的脆性曲线与根据目标 IM 直接开发的参考曲线一致。发现最不一致性的情况可能是由于用于获得转换方程所需项的模型。通过对为意大利高危场所设计的符合意大利规范的三层、六层和九层钢筋混凝土建筑的应用来说明转换策略。研究表明，在大多数情况下，转换的脆性曲线与根据目标 IM 直接开发的参考曲线一致。发现最不一致性的情况可能是由于用于获得转换方程所需项的模型。