斜拉-悬索体系转换中缆索共存状态结构力学研究

针对超大跨度自锚式悬索桥跨越通航流域时不能采用常规支架法施工主跨钢箱梁的问题，提出“先斜拉，后悬索”的总体施工方案，即利用钢塔和斜拉索辅助安装钢箱加劲梁，形成斜拉桥，然后再安装主缆、张拉吊索，进行斜拉桥-悬索桥的体系转换。完整的体系转换数值分析模型需要考虑斜拉桥和自锚式悬索桥两种独立缆索支撑体系共存，采用无应力状态控制法将两种模型全部缆索单元以无应力长度为基础重新建模迭代计算，获得耦合状态分析模型。推荐方案计算结果表明斜拉桥成桥后可充分利用斜拉索的材料强度进行补张拉工作后再进行体系转换工作，可使主梁线形大幅度提高，降低吊索张拉的接长杆长度和张拉次数，优化体系转换过程。通过数值模拟计算，分析得出两种缆索支撑体系共存状态下，体系转换过程中吊索和斜拉索的变化规律，研究了张拉吊索对相邻吊索、非相邻吊索索力的影响，以及成桥后吊索索力的来源比例。

Structural mechanics analysis on coexistent cable support system during system transformation from cable-stayed to suspension

 For the very long-span self-anchored suspension bridge crossing the navigable river basin, the conventional scaffolding construction method can’t be used to install the steel box girder of main span. Towards the above problem, the overall construction plan of “first cable-stayed, second suspension” was proposed. That is, the stiffening steel box girder was installed by making use of steel tower and stay cable to form the cable-stayed bridge. The main cable was installed and sling  was tensioned. Furthermore, the system transformation from cable-stayed bridge to self-anchored suspension bridge was carried out. In numerical analysis model of the complete system transformation, the coexistence of two independent cable support systems shall be considered. Using the unstressed state control method, all the cable units of the two models based on their unstressed length were used to rebuild the model for iterative calculation, so that the coupling state analysis model could be attained. The calculated results based on the recommended plan showed that after supplemental tensioning of the cable followed by the system transformation, the linear shape of main girder was significantly improved, the length of the extension bar of sling and the tensioning times were reduced, and the system transformation process was optimized. Based on numerical simulation and calculation, the changing rules of the sling and stay cable during system transformation were analyzed in the coexistent state of two cable support systems, the influences of tensioning siling on cable forces of adjacent and other nonadjacent silings were analyzed and the proportion of sources of cable forces after the completion of the bridge was also studied.