大跨径自锚式悬索桥几何非线性行为分析

Analysis of Geometric Nonlinear Behavior of Self-Anchored Suspension Bridge of Large Span

针对大跨径自锚式悬索桥的几何非线性问题,基于非线性分析的基本原理,采用了分次加载分析自锚式悬索桥几何非线性特征的方法,在借助全桥模型试验的基础上,研究了大跨径自锚式悬索桥在施工阶段和成桥阶段主缆位移的几何非线性行为,揭示了主缆位移的几何非线性特征以及结构体系转换对主缆位移几何非线性的影响规律。结果表明:施工阶段主缆位移的几何非线性行为变化显著,主要经历了线性化特征显著、非线性特征逐渐增强、非线性特征逐渐弱化的三个阶段,且已张拉吊索对应索夹点位置和未张拉吊索对应索夹点位置的几何非线性行为变化规律不相同,其中主缆位移影响线零点具有比其它主缆位置更为明显的几何非线性特征;成桥阶段主缆位移线性化特征显著,荷载效应符合叠加原理。

Considering with geometric nonlinear problem of self-anchored suspension bridge of large span, based on the basic principles of nonlinear analysis, a geometric nonlinear behavior of main cable＇ s displacement of large span suspension bridge in construction phase and at final stage was studied, by the method of analyzing the bridge＇ s geometric nonlinearity by loading fractionally. Besides, based on the comparison between theoretical calculation and measured experimental total bridge model test, the geometric nonlinearity characters of the main cable were clarified. The results show that the geometric nonlinearity character of the main cable＇ s displacement is obvious, and it mainly experiences three segments ： linearity character is obvious, nonlinearity character enhances gradually and nonlinearity character reduces gradually. Further analysis shows that the changing rules of the nonlinearity character of a cable band spot under tensioned or not are different ： the geometric nonlinearity character in the zero-crossing points of displacement influence line of the main cable is much more obvious than the other parts of the main cable. Under complete bridge stage, the linearity character of the main cable＇ s displacement is obvious and the load effect fits the superposition principle.