自锚式悬索桥体系转换实用计算分析

Practical calculation analysis of system transformation of self⁃anchored suspension bridge

为设计阶段更简洁方便地计算自锚式悬索桥在其体系转换过程中各吊索的张拉力,提出一种基于主缆内力状态计算吊索力的实用计算方法,根据吊索张拉完成的程度将主缆划分为张拉完成段与自由悬挂段两部分,借鉴结构力学中位移法的求解思路,首先在主缆相应吊点处添加约束使主缆张拉完成段内力与目标状态内力一致,然后释放约束使各主缆节段自由变形达到平衡得到该工况下的主缆状态.综合考虑约束释放前后各主缆节段能量守恒以及主缆的变形协调条件,建立主缆平衡方程求解得到体系转换完成后各主缆节段内力状态.再根据自锚式悬索桥各主缆节段间的竖向不平衡分力,求得该工况下各吊索力.通过与工程实例中的试验结果对比,结果表明:此方法计算方便简洁,无需依赖于上一阶段的效应状态,且计算精度满足要求,可用于一般跨径自锚式悬索桥的体系转换分析以及结构设计分析,对结构设计、优化具有一定的指导作用.

To conveniently calculate the tension force of each suspension cable of self⁃anchored suspension bridge during system transformation in design phase,a practical calculation method was proposed based on the internal force state of main cable.The main cable was divided into tension section and free suspension section according to the tension degree of the suspension cable.Based on the idea of displacement method in structural mechanics,the internal force of main cable tension section was made consistent with that of target state by adding restraints at the corresponding suspension points of main cable.Then the free deformation of each main cable segment was balanced by releasing the restraints to obtain the main cable state under this condition.Considering the energy conservation of each main cable segment before and after restraint release as well as the deformation compatibility conditions of the main cable,the equilibrium equation of the main cable was established and solved to obtain the internal forces of each main cable segment after system transformation.Next,according to the vertical unbalanced force between the main cable segments of the self⁃anchored suspension bridge,the cable forces under this condition were calculated.By comparing with the test results in engineering examples,it shows that the proposed method is convenient and concise,which is independent of the effect state of the former stage.The calculation results of the proposed method met the accuracy requirements,which can be applied in the system transformation analysis and structural design analysis of general self⁃anchored suspension bridges and might be the guidance for structural design and optimization.