考虑车-桥耦合的重载铁路钢桥局部疲劳分析

Local Fatigue Analysis of Heavy-haul Railway Steel Bridge Based on Train-bridge Coupled Vibration

研究目的:基于车-桥耦合振动理论,以64 m简支钢桁梁桥为实例,研究重载铁路钢桁梁桥局部疲劳可靠度问题。首先建立64 m简支钢桁梁桥的车-桥动力学模型,通过现场试验结果验证模型的准确性,并确定桥梁最不利疲劳部位;然后基于Monte Carlo方法,将车速和轨道不平顺作为随机变量,随机选取100个车速和轨道不平顺的组合样本;利用Miner线性疲劳累积准则和概率密度函数方法,得到钢桥最不利疲劳部位的等效应力范围和年疲劳损伤系数的概率分布,并给出桥梁局部疲劳损伤系数与列车编组的关系式;最后分析不同列车类型和行车速度条件对桥梁疲劳损伤的影响。研究结论:(1)在考虑参数随机概率分布的条件下,桥梁最不利疲劳部位的等效应力范围和年疲劳损伤系数均服从Lognormal分布;(2)当货运列车年运量一定时,列车轴重是桥梁局部损伤的主要影响因素,桥梁的疲劳损伤随轴重增加而增大;(3)在设计时速范围内,列车速度与桥梁疲劳损伤的相关性不强;(4)本研究成果可为重载铁路钢桁梁桥设计与疲劳性能评估提供参考。

Research purposes:Based on the theory of train-bridge coupled vibration,a 64 m simply supported steel truss bridge is taken as an example to study the local fatigue reliability of heavy-haul railway steel truss bridges.Firstly,the train-bridge dynamics model of 64 m simply supported steel truss bridge is established.The accuracy of the model is verified by field test result,and the most unfavorable fatigue parts of the bridge are determined;Then,based on the Monte Carlo method,the speed and the track irregularity are taken as random variables,and 100 combined samples of speed and track irregularity are randomly selected;The Miner linear fatigue accumulation criterion and the probability density function method are used to obtain the probability distribution of the equivalent stress range and the annual fatigue damage coefficient of the most unfavorable fatigue parts of the steel bridge,and the relationship between the local fatigue damage coefficient and the train formation;Finally,the effects of different train types and driving speed on bridge fatigue damage are analyzed.Research conclusions:(1)The equivalent stress range and the annual fatigue damage coefficient of the most unfavorable fatigue parts of the bridge are subject to the Lognormal distribution of the parameters.(2)When the annual freight volume of the train is constant,the axle load of the train is the main influencing factor.The fatigue damage of the bridge increases with the increase of the axle load.(3)In the design speed range,the correlation between train speed and bridge fatigue damage is not strong.(4)The research results can provide reference for the design and fatigue performance evaluation of heavy haul railway steel truss bridge.