桥墩地震易损性对地震波反应谱概率分布的敏感度

Sensitivity of seismic fragility of bridge columns on probability distributions of response spectra of earthquake ground motions

在基于性能的地震工程学理论(Performance-Based Earthquake Engineering,PBEE)中,正确选择输入地震波进行结构动力分析对计算结果的精确性具有显著影响。因此,合理选择一座钢筋混凝土单墩模型以及两组实际地震波,通过增量动力分析方法,获得桥墩结构地震易损性对于反应谱概率分布特性特别是离散度的敏感性,分析结果显示:地震波反应谱的离散度及其概率分布对于桥墩结构的地震需求预计、工程需求参数危险性曲线、地震易损性曲线等概率统计分析结果影响显著,具有密切相关性;但桥墩抗震能力的离散度同样对地震易损性曲线具有较大影响,甚至会削弱地震波反应谱离散度的影响。因此,对于以全概率理论为基础的PBEE,应尽量选择实际地震波进行结构动力分析,并尽可能使所选地震波的反应谱概率分布符合实际的地震环境,才能显著提高计算结果的精确性和计算效率。

The input ground motion selection for dynamic analysis of structures is very important to performance-based earthquake engineering（PBEE）and has significant effects on the precision of analytical results.A reinforced concrete bridge column and two bins of real earthquake ground motions are rationally selected for performing incremental dynamic analysis to analyze the sensitivity of seismic fragility of bridge columns on properties of probability distributions of response spectra of selected earthquake ground motions,especially dispersion.The analytical results show that the probabilistic seismic demand assessment,engineering demand parameter hazard curve and seismic fragility curve of bridge columns computed using probability and statistical analysis are closely related to the dispersion and probability distribution of response spectra of selected ground motions.The dispersion of seismic performance of bridge columns can remarkably affect seismic fragility curves and weaken the influence of dispersions of response spectra on seismic fragility curves.Real earthquake ground motions whose response spectra probabilistically match the target distribution at the bridge site are more applicable to dynamic analysis of structures for PBEE than simulated earthquake ground motions and can improve the precision and computation efficiency of analytical results.