提出基于车桥耦合动力分析的钢桥疲劳评估方法,建立车桥动力系统模型进行列车过桥耦合振动分析,求解桥梁构件疲劳应力,在此基础上,采用S-N曲线法对关键构件的疲劳损伤和剩余使用寿命进行评估.以一座铁路下承式钢桁梁桥为例,利用实测应力数据对所提方法进行验证,与既有方法评估结果进行比较,并研究了车速和轨道不平顺对桥梁疲劳性能的影响.结果表明:本文方法所得构件疲劳应力与实测数据符合较好,能够对铁路钢桥疲劳损伤和使用寿命进行准确评估;列车速度对桥梁疲劳性能有显著的影响,构件疲劳损伤程度并不一定随着车速的提高而增大;轨道不平顺能够显著影响桥梁疲劳损伤累积,轨道平顺性越好,构件疲劳损伤程度越低,加强轨道维护、保持良好轨道状态能够有效延长铁路钢桥的疲劳使用寿命.%Based on the train-bridge coupling dynamic analysis,an approach for fatigue assessment of steel bridges was proposed.The train-bridge dynamic system model was established to perform vibration analyses of the coupled train-bridge system,and to solve fatigue stresses in the bridge members,based on which,fatigue damage and remaining service life of the critical member were evaluated,using the S-N curve approach.Taking a through steel truss bridge as an example,the proposed approach was validated by using the measured stress data,and a comparison was made between the assessment results and those from the existing methods.The influence of train speed and track irregularities on the bridge fatigue behavior was investigated.The results showed that the fatigue stresses obtained from the proposed approach were in good conformity with the measured data,showing that the proposed approach can accurately assess the fatigue damage and service life of railway steel bridges.Train speed had a significant influence on the bridge fatigue behavior,and the level of the fatigue damage in the components did not necessarily increase with the increase of the train speed.Track irregularity can significantly affect the fatigue damage accumulation in the bridge,and the better the track smoothness,the lower the level of fatigue damage of the component became.Enhancing track maintenance and keeping good track conditions can effectively extend the fatigue service life of railway steel bridges.
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