武汉天兴洲公铁两用大桥疲劳四线系数的研究

四线铁路桥梁疲劳检算系数与各线列车在桥上的相遇次数及构件的荷载分配系数有关。根据列车过桥的随机性特点,运用概率理论分析四线列车在桥上的相遇概率和次数以及四线铁路桥在各种相遇情况下的损伤度,推导出四线铁路桥梁疲劳检算中四线系数的计算公式。运用该公式,以过桥长度1 092 m,横梁端剪力的荷载分配数据为依据,计算得武汉天兴洲大桥中间主桁疲劳检算四线系数为1.96。根据天兴洲大桥的结构及受力特点,综合分析所有情况的计算结果,建议天兴洲大桥疲劳四线系数取2.20。

Research on the Fatigue Quadruple Line Coefficient of Tianxingzhou Railway-Highway Combined Bridge in Wuhan

The fatigue quadruple line coefficient is related to the probability of encounter on the bridge and the load-distributed coefficient of each bridge member.Since the train passing the bridge is random,we use the probability theory to analyze the probability of the train encounter on the bridge and the fatigue damage,and then bring forward the calculation formula of fatigue quadruple line coefficient.In this paper,based on the fact that Tianxingzhou Bridge is 1 092 m long and the shearing force distribution of the crossbeam,we deduce that the fatigue quadruple line coefficient calculated is 1.96.According to structure and the mechanical characteristics of this bridge,the calculated results under all circumstances are synthetically analyzed.Finally it is suggested that the fatigue quadruple line coefficient of Tianxingzhou Bridge should be 2.20.