大跨斜拉桥上无缝线路纵向力的变化规律研究

Study on Variation Rules of Longitudinal Force of Continuous Welded Rails on Long-span Cable-stayed Bridge

研究目的:大跨度斜拉桥结构复杂,为"塔-索-梁"空间组合结构,铺设无缝线路后,在荷载作用下,会形成"塔-索-梁-轨"耦合作用体系,其无缝线路力学传递机理极为复杂。以安庆长江大桥为例,通过建立大跨度钢桁梁斜拉桥上无缝线路"塔-索-梁-轨"空间耦合计算模型,分析不同体系温差、斜拉索修正弹性模量、纵向阻力模型及小阻力扣件的影响,为大跨度斜拉桥上无缝线路设计提供理论依据。研究结论:研究结果表明,随着斜拉桥体系温差变化幅度增大,钢轨伸缩附加力明显增加;斜拉索弹性模量修正与否对伸缩力和制动力影响较小,而对挠曲力影响较大;采用不同纵向阻力模型,伸缩力计算结果相差不大,挠曲力和制动力计算结果有较大差别;采用小阻力扣件可降低无缝线路纵向附加力,且应结合工程造价优先考虑在斜拉桥边跨和两侧引桥上铺设小阻力扣件方案。

Research purposes： The structure of cable - stayed bridge is a complicated spacial composite structure of ＂tower - cable - beam＂. After the laying continuous welded rails, a ＂tower - cable - beam - track＂ coupling system is formed under the load effect , with the complicated mechanical transmission mechanism of continuous welded rails. Taking the Anqing Yangtze River Bridge as an example, a ＂ tower - cable - beam - track＂ spatial coupling model is established for calculating the longitudinal force of continuous welded rails on long - span cable - stayed bridge to analyze the influences of the different system temperature, the modified elastic modulus of the cable, longitudinal resistance model and the fastening with small resistance for providing the theoretical basis for the design of CWR on long - span cable- stayed bridge. Research conclusions： The research result shows with the increase of the variation range of the system temperature of the cable - stayed bridge, the expansion - constriction force increases obviously. The modified elastic modulus of cable has less effect on the additional expansion - constriction force and braking force, but has big effect on the additional flexural force. The additional expansion- constriction force calculated by using two different longitudinal resistance models are almost the same, but there is distinct discrepancy in the calculation results of the flexural force and braking force. Application of the fastenings with small resistance can decrease the additional longitudinal force in CWR, so it should be used for the CWR on the side span of the cable - stayed bridge and on the approach bridges on consideration of the engineering cost.