中国RC框架结构地震易损性曲线的可信性分析

CREDIBILITY ANALYSIS OF SEISMIC FRAGILITY CURVES FOR REINFORCED CONCRETE FRAME STRUCTURES IN CHINA

  • 摘要: 钢筋混凝土框架作为中国建筑抗震体系的核心载体,其易损性模型可信性直接影响地震风险评估精度。中国学者已研究获得大量RC框架易损性模型,但这些成果大多基于数值模拟方法,比较分散、孤立,缺乏系统梳理和检验。该研究提出一种基于机器学习的地震易损性数据清洗方法。构建中文文献易损性曲线数据库,采用机器学习模型建立结构参数与易损性曲线50%超越概率对应的谱加速度Sam(T1)的映射关系,采用最优选择策略通过敏感性分析识别离群样本和合群样本,分析其在样本空间中的分布特征并结合SHAP与实际工程经验对模型进行验证;并以HAZUS中的典型RC框架结构为例,讨论了该文模型拟合易损性曲线与灾害评估模型提供的易损性曲线的差异。结果表明:中国现有中文文献中RC框架原型结构的特征取值具有不均匀性的特点;中国现行中文文献计算的RC框架结构易损性曲线大部分是可信的;相较传统灾害评估模型,该文机器学习给出的易损性曲线在参数维度与样本覆盖度上具有更准确的描述能力,更适用于单体结构及区域化的精细评估。基于该文研究内容,开发了可判断给定曲线可信性及快速生成给定RC框架结构易损性曲线的可视化程序。

     

    Abstract: Reinforced concrete (RC) frame is predominant of China’s seismic-resistant building systems. The credibility of its fragility model directly affects the accuracy of earthquake risk assessment. Although significant advances have been made in seismic fragility modeling of RC frames, the results are mostly based on numerical simulations, lacking systematic integration and validation. This study developed a machine learning-driven cleaning method. Based on a database comprising fragility curves from Chinese literature, the mapping relationship between structural parameters and spectral acceleration Sam(T1) was firstly established by machine learning models, which corresponds to a 50% exceedance probability in the fragility curve. A sensitivity simulation was performed to identify disqualified samples and qualified samples within the fragility curve database with greedy algorithm. An analysis of distribution characteristics in the sample space was performed combined with SHAP (Shapley Additive Explanations) and engineering experience. The differences between the fragility curves fitted by this paper's model and the curves provided by disaster assessment software were discussed with the examples of classical RC frame structures in HAZUS. The results indicate that the engineering parameters of the RC frame prototype structure in available Chinese literature are non-uniform. Fragility curves given in current Chinese literature for RC frame structures are mostly credible. The comparison with HAZUS benchmarks demonstrates that the machine learning models show advantages in parametric dimensions and material coverage with more applicablity to single structure. A visualization platform based on research has been developed for evaluating the credibility of existing fragility curves and automatically generating structure-specific fragility curves for RC frame systems rapidly.

     

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