公路斜交梁桥地震易损性模型研究

RESEARCH OF SEISMIC VULNERABILITY MODEL FOR SKEW HIGHWAY GIRDER BRIDGE

采用增量动力分析方法建立公路斜交梁桥地震易损性模型并开展易损性简化计算方法研究。依据不同的墩柱形式、支承形式及新旧规范将公路斜交梁桥分成8种桥型,统计桥梁结构参数并采用随机抽样方法确定其相应取值,依此装配生成240个基准桥梁样本,同时进行斜交角度变换建构新的桥梁样本。基于增量动力分析方法对相同斜交角下桥梁样本进行分析并建立易损性模型,重点研究斜交角与易损性参数之间的关系。研究发现:易损性模型中位值大致随斜交角的增加而减小,对数标准差则呈相反趋势。以计算得到的易损性模型参数为样本,拟合提出适用我国斜交梁桥的中位值修正系数公式,同时给出对数标准差的建议值,进一步总结公路斜交梁桥地震易损性简化计算方法,结果可为后续斜交梁桥地震风险评估及加固规范修订提供参考依据。

Seismic vulnerability models of skew highway girder bridges were developed using the incremental dynamic analysis approach, and simplified calculation methods of vulnerability were discussed. According to the different pier types, supporting types and design of old and present specifications, the skew highway girder bridges were categorized into eight groups. The samples of 240 benchmark bridges were constructed with different values of the bridge structural parameters, which were determined and summarized by using the random sampling method. On the basis of the benchmark samples, a series of new bridge samples were created with varying values of the skew angles. By using the incremental dynamic analysis method, the seismic vulnerability of the bridge samples with the same skew angles was analyzed. The relationship between the skew angles and the seismic fragility parameters was analyzed. The results showed that the median value of the seismic fragility decreases when the skew angle is increased while the logarithmic standard deviation of the seismic fragility changes in the opposite trend. A new correction formula of the median value was fitted and proposed for the existing skew highway bridges in China. Values of logarithmic standard deviation were also recommended. A simplified calculation method for seismic vulnerability of skew highway bridges was derived. The relevant result could be beneficial to the seismic risk assessment and the retrofitting codes of skew bridges.