斜拉桥施工阶段主梁截面温差效应计算研究  

Research on calculation of temperature variation effects of beam sections under construction of cable-stayed bridges

作　　者：付春雨 严鹏 唐波 FU Chunyu;YAN Peng;TANG Bo(School of Civil and Transportation Engineering,Hohai University,Nanjing 210098,China;China SWJTU Railway Development Co.,Ltd.,Chengdu 610073,China;China Railway Guangzhou Group Co.,Ltd.,Guangzhou 510080,China)

机构地区：[1]河海大学土木与交通工程学院,江苏南京210098 [2]四川西南交大铁路发展股份有限公司,四川成都610073 [3]中国铁路广州局集团有限公司,广东广州510080

出　　处：《铁道科学与工程学报》2022年第9期2654-2661,共8页Journal of Railway Science and Engineering

基　　金：国家铁路集团有限公司科技研究开发计划课题(N2019G059)。

摘　　要：为揭示主梁竖向截面温差作用对施工阶段斜拉桥的影响机理,准确预测斜拉桥结构的截面温差效应,将斜拉桥主梁视为一根连续弹性支承的地基梁,其支承刚度取决于斜拉索的竖向抗拉刚度。对主梁微段进行内力分析,建立微段的内力平衡微分方程;结合温差变形和支承边界条件,对方程进行求解,获得结构应力和变形,由此提出一种斜拉桥结构主梁截面温差效应的解析方法。通过与实桥算例的有限元数值分析结果对比,发现所提出的方法能够准确预测竖向截面温差作用下斜拉桥主梁的结构应力与变形,并进一步分析结构响应在斜拉桥施工过程中的变化规律,以及斜拉索刚度变化对该效应的影响。研究结果表明:截面温差作用只会在主梁悬臂端引起较大结构变形;而主梁其他部位受到拉索和桥塔的约束作用,变形量很小,但由于约束作用的存在,其温差应力较大,尤其在塔梁连接处应力值达到最大;而且温差应力随着施工悬臂长度的增加而增大,当桥梁施工至大悬臂状态下,主梁的底板与腹板均会出现较大的拉应力,应通过增加预应力等措施抵消或减小这部分拉应力;但温差效应受斜拉索支承刚度的影响较小,因此采用中间索的平均支承刚度作为计算模型的支承刚度,能够满足工程需求,也减少了计算量,便于工程设计。In order to investigate the mechanism of temperature variation effects of beam sections on cable-stayed bridges under construction and predict these effects exactly,the bridge beam was viewed as a foundation beam with continuous elastically supports,and the support stiffness depended on the vertical tensile stiffness of cables.The internal forces of beam segments were analyzed,and the differential equilibrium equations of internal forces were built.Then based on the thermal deformations and support boundaries,the equations were solved and the structural stresses and deformations were obtained.Thus,an analytic method for temperature stresses and deformations was put forward.The effectiveness of the method in predicting the bridge responses caused by the temperature load was validated by using finite element numerical results of a real bridge.Then the change of the structural responses in the construction process and the effects of cable stiffness on the responses were further studied.The results show that the temperature variation only can produce a large deformation at the cantilever end.Meanwhile,due to the supports of the cables and tower,the deformation of other parts is small,but the temperature stresses are big,especially at the beam and tower connection the stress is biggest.Besides,the stress increases with the cantilever length of the beam under construction,and large tensile stresses appear at the bottom and web of the beam under the large cantilever construction stages,so the tensile stresses should be eliminated or minished by adding the beam prestress.However,the temperature effects are less influenced by the support stiffness of cables.When the average stiffness of the middle cable is taken as the support stiffness of the proposed method,the results can meet the engineering requirement,also reduce the computation and make the engineering design convenient.

关 键 词：斜拉桥 主梁截面温差 施工阶段 弹性地基梁 温度应力 悬臂长度 

分 类 号：U441.5[建筑科学—桥梁与隧道工程]