千米级主跨公铁两用桥上特殊梁-轨相互作用关系研究

Study on Peculiar Beam-rail Interaction on Road-cum-rail Bridges with Thousand-meter-scale Main Span

为研究复杂环境下因千米级主跨公铁两用桥梁结构特殊性引起的梁-轨相互作用问题,建立可考虑桥塔及索缆影响的无缝线路-悬索桥空间耦合模型,分析了公路车辆、横向风、主梁温差作用下的梁-轨相互作用变化规律。研究结果表明:对于千米级主跨公铁两用桥上无缝线路,公路车辆及横向风荷载虽然对线路的平顺性影响较小,但对钢轨纵向附加力及梁-轨相对位移的影响不容忽视;梁体整体降温15℃计算出的伸缩力比考虑板桁温差效应的结果偏大54.5%;上、下游主桁温差导致线路全线存在梁-轨相对位移,是千米级主跨桥上无缝线路不存在传统意义上的“固定区”的重要原因之一。因此,在千米级主跨公铁两用桥上无缝线路设计及运维过程中,建议考虑上述特殊梁-轨相互作用带来的影响。

To improve the understanding of the beam-rail interaction caused by the structural particularity of road-cum-rail bridges with thousand-meter-scale main span,a spatial coupling FEM of a suspension bridge and the CWR above it was established to analyze the influence of the beam-rail interaction under highway vehicles load,lateral wind,and temperature difference of the main beam,with fully considering of the impact of towers and cables of the bridge.The results show that in terms of the CWR on the road-cum-rail bridges with thousand-meter-scale main span,the influence of the highway vehicle load and lateral wind load on the regularity of the track is slight,while that on the longitudinal additional force of rails and the beam-rail relative displacements should not be ignored.The calculation result of the additional force of rail expansion is about 54.5[WTB4]%greater if the effect of the temperature difference between the plate and truss is taken into account and both of them are cooled by 15℃.The temperature difference between the upstream and downstream main trusses leads to the relative displacement of beam and rail along the whole line,which is one of the important reasons why"fixed zone"of CWR does not exist on kilometer level bridges.It is recommended to consider the impact of the beam-rail interaction during the design,operation and maintenance of the CWR on the road-cum-rail bridges with thousand-meter-scale main span.