现代有轨电车小半径曲线桥桥墩横向刚度研究

RESEARCH ON LATERAL RIGIDITY OF SHARPLY CURVED BRIDGE PIER IN MODERN TRAM LINE

现代有轨电车小半径曲线桥梁桥墩横向刚度对线路的平顺性有重要影响。基于有限元法,建立曲线桥梁-无缝线路空间耦合作用计算模型,以某35 m+40 m+40 m+35 m曲线钢-混组合桥为例,分析了多种因素对轨向不平顺的影响。结果表明:曲线桥上无缝线路会因纵、横向梁轨耦合作用引起中长波的轨向不平顺;轨向不平顺幅值与桥墩纵向刚度、轨温变化幅度、扣件纵向阻力极限荷载正相关,与桥墩横向刚度、曲线半径、扣件纵向阻力弹塑性临界位移负相关,其中曲线半径影响最为显著;曲线半径从150 m增加至600 m,中点弦测法、矢距差法所确定的轨向不平顺幅值降幅均超过60%;确定了有轨电车常用跨度连续梁桥在不同曲线半径条件下对应的桥墩横向刚度限值,其中钢-混组合桥对应桥墩横向刚度限值是同等条件钢筋混凝土桥的1.2倍~2.0倍。建议曲线桥上无缝线路设计中优化锁定轨温,或采用小阻力扣件,可有效降低因梁轨相互作用引起的轨向不平顺幅值和桥墩横向刚度限值。

The lateral rigidity of a sharply curved bridge(SCB)pier has an important impact on regularities of the track in modern tram lines.A spatial calculation model for SCB-CWR(continuous welded rail)interaction is established by the grounds of the finite element method.Taking the example of a curved steel-concrete composite bridge with spans of 35 m+40 m+40 m+35 m,the effects of different factors on TAI(track alignment irregularity)are analyzed.The results show that the coupling between longitudinal and lateral SCB-CWR interactions can cause middle and long wave TAI.The amplitude of TAI shows a positive correlation with longitudinal rigidity of a pier,with the variation range of rail temperature and,with the maximum force of fastener longitudina resistance,but a negative correlation with lateral rigidity of a pier,with curve radius and,with the yield displacement of fastener longitudinal resistance.The most significant factor is curve radius.When the radius increases from 150 m to 600 m,the amplitudes of TAI determined by the mid-chord offset method and by the differential offset method reduce by more than 60%.The lateral rigidity thresholds of piers for common curved continuous beam bridges in modern tram lines are ascertained respectively.The thresholds of steel-concrete composite bridges are 1.2~2.0 times greater than that of reinforced concrete bridges.Optimizing design stress-free rail temperature or using small resistance fastener which can effectively reduce the amplitude of TAI and the lateral rigidity thresholds of piers are recommended to be applied during the design of CWR on SCB.