杭绍台铁路大跨斜拉桥相关设计问题探讨

Discussion on Related Design Issues of Long-span Cable-stayed Bridges on Hangzhou-Shaoxing-Taizhou Railway

铁路大跨度斜拉桥设计目前还缺少相应的技术标准及设计规范。结合杭绍台铁路椒江特大桥(84+156+480+156+84)m四线连续钢桁斜拉桥施工图审核,在进行结构验算的同时,提出相关设计问题探讨:(1)对于大跨度斜拉桥竖向刚度限值,现行规范中未明确规定,本桥计算结果在已建成同类桥梁的指标范围内;(2)大跨度斜拉桥梁体横向变形控制应结合车桥耦合动力仿真分析评估行车的安全舒适性;(3)温度荷载参数取值标准在无准确实际气象资料时,建议保守取值;(4)大节段整体吊装分段的接缝设置,应兼顾节点构造和杆件受力最小位置综合确定;(5)压重措施应考虑钢箱梁刚度平缓过渡,避免刚度突变而产生应力集中;(6)梁体成桥线型应综合考虑预拱度和纵断面竖曲线的影响;(7)现行规范对超长桩承载力计算公式、有效桩长等问题未明确要求,有必要进行深入研究;(8)索塔与钢桁梁交错多层作业,施工组织存在交叉干扰问题,存在一定安全隐患,应采取必要的安全防范措施。

For the design of railway long-span cable-stayed bridges,there has been a shortage of corresponding technical standards and design specifications.Combined with the review of the construction drawing of the Jiaojiang Bridge on Hangzhou-Shaoxing-Taizhou railway,a cable-stayed bridge of four-line railway continuous steel truss girder with a span arrangement of(84+156+480+156+84)m,structural check and calculation are conducted and following relevant design issues are proposed for discussion:(1)For long-span cable-stayed bridges,the vertical stiffness limit values are not clearly stipulated in the current specifications,and the calculation results of this bridge are within the index range of the similar bridges built;(2)The lateral deformation requirements of beam body of long-span cable-stayed bridges shall be combined with simulation analysis on train-bridge coupling vibration force to evaluate traffic safety and comfortableness;(3)It is suggested that the values of temperature load parameters shall be conservative in the absence of accurate actual meteorological data;(4)The joint setting of the large segment integral hoisting section shall be comprehensively determined by taking into account the node construction and the position where the bar has the least stress;(5)In order to avoid stress concentration for structural stiffness mutation,the weight measures shall consider the smooth transition of the stiffness of the steel box girder;(6)The linear of beams into bridge shall comprehensively consider the influence of the pre-camber and the perpendicular curve on vertical section;(7)There has been no specific requirement in the current specifications for issues such as calculation formula of bearing capacity for overlength piles and effective length of foundation pile,and further in-depth researcher are necessary;(8)There are some security risks due to staggered multi-layer operation of cable pylon and steel truss girder,and cross-interference problems in construction organization should be addressed.