下承式系杆拱桥结构体系内力分布优化分析

Analysis of Optimizing Internal Force Distribution of Structural System of Through Tied-arch Bridge

为改善下承式系杆拱桥结构体系受力性能,提高设计效率,采用有限元法对下承式系杆拱桥进行力学数值分析,在不改变结构构造参数的前提下,通过研究吊杆、系杆张力和拱轴线形状对下承式系杆拱桥内力分布的影响,构建下承式系杆拱桥内力分布优化分析方法。研究结果表明:以拱肋、吊杆和系杆组成的结构体系应变能最小为目标,采用无约束优化算法可对吊杆和系杆张力进行优化;以拱肋截面偏心距最小为目标,采用三次样条插值函数进行拱轴线拟合,能快速得到与吊杆和系杆张力优化值对应的拱轴线;合适的吊杆、系杆张力和拱轴线形状,可以优化下承式系杆拱桥结构体系内力分布,提升下承式系杆拱桥结构体系安全性。

In order to improve the mechanical behavior and design efficiency of structural system of through tied-arch bridge,the mechanical numerical analysis of the bridge is performed with finite element method. On the premise of not changing the structural parameters,the internal force distribution optimizing method of through tied-arch bridge is formed after studying the influence of the tension force of hangers and tied bars,the lineshape of arch axis on the internal force distribution of the bridge. The result indicates that（ 1） focusing on the minimum strain energy of structural system which contains of arch rib,hangers and tied bar,the unconstrained optimization algorithm is used to optimize the tension forces of hangers and tied bar;（ 2） aiming at the minimum section eccentricity of the arch rib,the lineshape of arch axis corresponding to the tension forces of hangers and tied bars is attained rapidly by fitting the lineshape of arch axis with cubic spline interpolation function;（ 3） reasonable tension forces of hangers and tied bar and lineshape of arch axis can lead to an optimized the internal force distribution and improve the safety of through tied-arch bridge.