大跨径多塔斜拉桥恒载索力优化方法

Optimization Method of Cable Force for Large-Span Multi-Towerer Cable-Stayed Bridges under Dead Load

基于斜拉桥传统索力优化理论,提出3阶段优化算法。该算法以既定的合理成桥状态准则为目标,运用刚性支承连续梁法获得初始成桥状态,利用零位移法实现结构线形目标,以弯曲能量最小为目标,指定各种约束条件,利用ANSYS优化模块中的1阶优化方法实施索力优化,获得目标成桥状态,求解过程中考虑几何非线性的影响。建立3~6塔主跨为1 400 m斜拉桥的有限元模型,利用参数化设计语言(APDL)编制计算程序,进行算例分析。结果表明:微调索力,结构变形改变量较小,而结构内力变化显著;索力优化前后,塔、梁恒载弯矩明显减小,结构内力和变形均能满足既定目标;运用该算法进行3~6塔斜拉桥成桥状态计算,结构内力和变形均能满足既定目标。

Based on optimization method of cable force for traditional cable-stayed bridge, three-stage optimization algorithm is proposed. In order to realize the target according to the criterion of reasonable completed status, the algorithm using rigid supported continuous beam method to calculate the initial cable force of these bridges. Then, using zero displacement method, the algorithm makes structural displacement be close to zero. Finally, taking the minimum bending energy as the optimization object and setting constraint conditions according to the reasonable finished dead state, the models are solved by the first order optimization method of ANSYS to obtain reasonable dead state, with geometric nonlinearity being considered. Four finite element models of three-tower to six-tower cable-stayed bridge with the span of 1400m are established and are used to establish mathematic optimization model for cable force with the algorithm realized by using ANSYS parametric design language （APDL）. Calculated results show that： fine-tuning cable force, structure displacement slightly changes, yet the internal force remarkably changes. After the optimization, the bending moment of girder and pylon significantly decrease, and meet desired goal. Using the algorithm to analysis, internal force and deflection of all structures can meet desired goal.