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为获得活载作用下三塔两跨悬索桥变形解析公式,首先通过微分与变分方法推导了均布荷载作用下单跨主缆挠度的解析计算公式,通过综合研究塔顶位移及主缆弹性伸长引起的主缆变形,推导了用于计算三塔两跨悬索桥中塔塔顶位移及加劲梁挠度的解析计算公式。研究发现,对单跨主缆施加均布荷载时,恒载大小对于主缆变形影响不大,主缆变形主要由缆的弹性伸长所引起,取决于主缆的轴向刚度及垂跨比;三塔两跨悬索桥的变形主要取决于中塔的变形以及主缆的伸长。建立三塔两跨悬索桥模型对本文公式进行验证,结果表明,公式能有效对塔顶位移及加劲梁挠度进行估算,可用于初步设计时对三塔悬索桥进行简化分析。
In order to obtain the deformation analysis formula of a three-span two-span suspension bridge under live load, the analytic formula of single-span main cable deflection under uniform load is deduced firstly by means of differential and variational methods. Long deformation of the main cable, the analytical formula for calculating the tower top displacement and stiffening girder deflection in three-tower and two-span suspension bridge is deduced. It is found that when a uniform load is applied to a single span main cable, the size of the dead load has little effect on the deformation of the main cable, and the deformation of the main cable is mainly caused by the elastic elongation of the cable, depending on the axial rigidity of the main cable and the vertical ratio Three-tower two-span suspension bridge deformation depends mainly on the tower deformation and the main cable elongation. The model of three-tower and two-span suspension bridge is established. The results show that the formula can effectively estimate the displacement of the tower and the deflection of the stiffening girder. It can be used to simplify the analysis of the three-tower suspension bridge during the preliminary design.