大岩洞特大桥拱圈脱架时背索和扣索索力优化计算

Optimal Computation on Cable Force in Arch Ring Support Dismantling for Dayandong Super Bridge

建立了大岩洞特大桥拱圈平转施工状态的三维有限元模型,交界墩和上转盘采用实体单元,扣索和背索采用索单元,拱圈劲性骨架底板采用壳单元,其余采用梁单元,支架则采用只压单元模拟;将最优化计算理论和有限元计算分析相结合,利用MIDAS有限元软件,以支架不受轴压或受压轴力很小为目标函数,对扣索力和背索力进行优化,使拱圈"脱离"支架实现转体,从而获得了扣索力和背索力的最优组合与拱圈最优内力分布.结果表明,拱圈骨架拱脚底板为控制截面,本文计算方法和结论为同类桥梁的建设具有参考价值.

Three-dimensional model of Dayandong super bridge arch ring in swiveling construction situation is created. The solid element is adopted to the boundary pier and top turntable, the cable element to the tension of cable and back cable,the shell element to the bottom slab of filled steel tube of arch ring and the beam to the others, while the compression-only element to the supporting frame. By combining optimum calculate theory and FEM analysis together and making use of M1DAS FEM software, the tension of cable and back cable are optimized by use supporting frame without or with little axial compression as object function. Consquently, the arch rib is kept from supporting frame to swiveling construction, and the optimum combination of the cable force and optimum stress distribution in arch ring is acquired. The results show that the base plate of arch ring is the control section, and the calculate method and conclusion have reference value to bridge construction of the same type.