【作者】 刘伟长；

【导师】 赵跃宇；

【作者基本信息】 湖南大学 ， 桥梁与隧道工程， 2006， 硕士

【摘要】 斜拉拱桥作为近年来出现的一种新型组合桥梁,其理论研究目前还处于起步阶段。斜拉拱桥作为拱桥和斜拉桥的组合体系,其稳定性是设计、施工中的一个重点环节,本文结合湘潭湘江四大桥主桥模型实验,对斜拉拱桥的稳定性作了一些具体研究。在总结前人对圆弧拱的面内,面外屈曲临界荷载计算方法的基础上,利用能量法,推导了斜拉拱桥的侧倾临界荷载计算公式。在此基础上,以在建的湘潭湘江四大桥为工程背景,利用大型有限元软件ANSYS,考虑几何非线性和材料非线性,建立了该桥空间三维有限元模型,并分析了该桥在三种不同荷载工况下的稳定性。计算结果表明,在不同的加载工况下,几何非线性对结构的临界荷载影响程度不同,几何非线性对全桥均布活荷载作用下的临界荷载影响较小,考虑几何非线性后,临界荷载仅下降了10%,而在半桥均布活荷载和集中荷载作用下,几何非线性对其临界荷载影响很大,考虑后其临界荷载分别下降了35.38%和74.08%。在三种加载工况作用下,考虑双重非线性的临界荷载远小于线弹性和仅考虑几何非线性临界荷载。因此,采用线弹性和仅考虑几何非线性方法均会过高地估计结构的极限承载力,要准确评估出结构的极限承载力必须考虑双重非线性。本文还通过改变横撑的布置形式、刚度及斜拉索的索力,分析了横撑和斜拉索对斜拉拱桥稳定性的影响。结果表明,横撑的布置形式对其稳定性影响很大,而其刚度相对要小些;斜拉索的存在能明显提高其稳定性,斜拉索索力的大小对其稳定性有一定的影响,索力越大,稳定安全系数越高。最后,为了研究湘潭湘江四大桥的实际受力性能及稳定性,对该桥进行了模型试验研究。从试验结果可以看出,该桥在恒载加四倍设计活载作用下,结构受力状态良好,没有出现面内、面外的整体失稳,也没有出现桁架的局部失稳。更多还原

【Abstract】 Cable stayed arch bridge is a kind of new combination bridge appeared in recent years, its theories studies to still be placed in a beginning stage so far. Cable stayed arch bridge as arched bridge with cable stayed bridge of combination system, its stability is an important link of design and construction.This paper studies the stability of cable stayed arch bridge, combined the main bridge model experiment of the fourth bridge of Xiangtan Xiangjiang river.In summarizes the predecessor to the segmental arch surface and outside in flexure critical load computational method foundation,with the principle of the minimum potential energy, an analytical solution for the lateral critical bucking load of cable stayed arch bridge is studied. In this foundation,taking the Xiangtan Xiangjiang River four bridges which constructs as the project background, the 3-D finite element model was built and the stability of three load cases is studied using the common finite element method software-ANSYS, considering geometric nonlinearity and material nonlinearity. The result indicate that the influences of geometrical nonlinearity is different to the structure critical load under different load cases.Under the live uniform load, the structure critical load decreases 10% after considering the geometric nonlinearity; and under the live uniform load or concentrated load act on half bridge, the structure critical load decreases 35.38% or 74.08% after considering the geometric nonlinearity. And under the three load cases, the critical load of the cable-stayed arch bridge taking into account double nonlinearity is much smaller than taking into account linear elasticity or geometrical nonlinearity.Therefore if we want to estimate the limit bearing capacity exactly, the double nonlinearity must be considered. In this paper, the influence of lateral connections and stayed cables to the stability of cable-stayed bridge is studied. The result indicates that the layout of lateral connections influence to the stability more greatly than the rigidity of lateral connection; The stayed cables can help much on increasing the stability of cable-stayed bridge; The force of stayed cables have something to do with the stability of cable-stayed bridge, higher the force, higher the stability coefficient.At last, in order to study the practical stability performance of the Xiangtan Xiangjiang River four bridges, a total bridge model test was carried through. From the test results we can know that under the dead load and quadruple designing live load,更多还原