三塔自锚式悬索桥力学性能分析.doc

摘要 三塔自锚式悬索桥是一种新结构形式，不仅省去了庞大的锚锭，相对降低了造价，外形也比较美观，因此应该会越来越受到人们的青睐，对中小跨径的桥梁设计来说，三塔自锚式悬索桥是一个适合的且有竞争力的桥型。本文在总结国内外相关文献的基础上，以螺洲大桥为工程实例，对三塔自锚式悬索桥的力学特性以及各设计参数变化对内力的影响规律进行了仔细的研究， 根据螺洲大桥三塔自锚式悬索桥的结构特点，采用桥梁有限元计算程序midas/civil对桥梁进行离散，建立了三塔自锚式悬索桥的空间有限元计算模型那个，对该桥进行了静、动力分析，对各种控制因素进行研究和比较，主要结论如下: (1)以螺洲大桥大桥为背景，研究了混凝土自锚式悬索桥的静力性能，分析比较了三塔自锚式悬索桥与地锚式悬索桥的差别，自锚式悬索桥的跨中弯矩和挠度均比地锚式悬索桥的要大一些，这主要是因为自锚式悬索桥主梁中存在着巨大的轴向压力，从而降低了主梁的刚度。弹性理论和非线性有限元模型计算结果比较接近，对于中小跨径的自锚式悬索桥，弹性理论完全可以进行设计计算和分析。 （2）系统地研究了三塔自锚式矢跨比、桥塔塔高差异、桥面纵坡、加劲梁刚度、主塔刚度、主缆刚度、吊索刚度等结构参数变化对三塔自锚式悬索桥静力及动力特性的影响规律。主梁的跨中挠度和弯矩均与主塔刚度、主缆和吊索的弹性模量成反比；与桥塔塔高差异、桥面纵坡成正比；增大加劲梁的抗弯惯性矩能有效减少主梁的跨中挠度，但同时也使主梁跨中的弯矩大大增加。 (3)基于有限元原理，建立了螺州大桥的动力计算模型，给出了螺洲大桥的前10阶频率和相应的振型。从结果来看，该桥的自振周期较长体现了悬索桥的柔性结构的特性。与同一跨径和结构参数的地锚式悬索桥相比混凝土自锚式悬索桥的自振周期长很多，说明自锚式体系要比同样结构参数的地锚式体系的刚度要小一些。 关键词:自锚式悬索桥；三塔；有限元；力学性能； Abstract The three-tower self-anchored suspension bridge is a kind of new structural style. With no large anchor and its lower cost ,three-tower self-anchored suspension bridge is now catching more attention by its elegant shape. It has become a competitive design scheme in middle and small-span bridge .Base on the documents at home and abroad,regarding Luozhou three-tower self-anchored suspension bridge as project example ,the static force performance and dynamic behavior of three-tower self-anchored suspension bridge are systematically investigated in this paper . According to Louzhou three-tower self-anchored bridge’s structure characteristic,we use midas/civil finite element program,a space finite element calculated model was established. We anslysed its static、dynamical characteristic and compared various control parameter.The main conclusion covers the follwing aspects: (1) Based on Luozhou Bridge ,the static force performace of the three-tower slef-anchored suspension birdge is analyzed.The difference of between the three-tower eathe-anchored suspension bridge is revealed in this paper.Bending momnet and deflection at the span midpoint of the three-tower self-anchored are greater than