【作者】 翁丽花；

【导师】 杨炳成；

【作者基本信息】 长安大学 ， 桥梁与隧道工程， 2008， 硕士

【摘要】 随着我国公路和城市道路的迅速发展,高架道路及立体交叉工程愈来愈多,弯梁桥的运用越来越广泛。与直线梁桥相比,弯梁桥存在着弯矩和扭矩互相耦合的独特力学性质。弯梁桥不同的支承形式将直接影响到全桥的内力分布,支承形式的改变,会使弯梁桥的弯扭耦合程度也发生改变。在弯梁桥的设计中,通过选择合适的支承形式可以调整截面的受力状态,有利于弯梁桥的优化设计,可获得显著的经济效益。本文总结了弯梁桥的四种计算理论,并在符拉索夫方程的基础上,给出了简支超静定弯梁桥的闭合解以及有限差分法数值解;详细地研究了梁格法等效模拟箱梁的基本理论,从梁格网格划分、截面特性计算及输出结果处理等方面进行了系统分析,探讨采用梁格法分析弯箱梁时较为合理的网格划分方法,以及合理的梁格刚度等效原则和计算结果的处理方法。基于梁格法原理,运用MIDAS/Civil有限元软件建立梁格模型,分析了不同的支承形式对弯梁桥结构的影响,得出支承形式的改变对弯梁桥扭矩的影响很大,而对剪力和弯矩的影响微小的结论;提出了通过预设支座偏心、减小扭转跨径和拉大端支座间距的方法,以增强弯梁桥的抗扭能力;对具有不同中支座偏心距的弯梁桥进行分析计算,得出适当选取支座预偏心,可以使得梁端支承点不脱空、内侧支座不出现负反力,可以使得弯梁桥的扭矩满足最大值与最小值接近相等;最后总结了弯梁桥应当如何布置支承体系,以保证支承约束既能适应弯梁桥的受力和变形,又能保证结构的安全稳定;提出了施工温度不同时对支座进行偏心调整的措施,为弯梁桥的设计和同类工程的处理提供参考和借鉴。更多还原

【Abstract】 Due to the rapid development of highways and city roads of our country, more and more elevated roads and city overhead crossings are built, which lead to the wider application of curved girder bridges. Compared to the straight beam bridges, curved girder bridges have the particular mechanical characteristic of bending moment-torsion coupling. Different supporting forms will directly affect the whole internal force distribution in curved girder bridges. The variation of the supporting form will change the degree of bending moment-torsion coupling. In the design of curved girder bridges, the force state of the section can be adjusted by selecting suitable supporting forms. It is beneficial to the optimal design of curved girder bridges and can obtain significant economic benefit.This thesis summarized four kinds of calculation theories of curved girder bridges, in which the closed solution and finite difference method numerical solution of simple supported statically indeterminate curved girder bridges are given based on Vlasov Equation, and the basic theory of grillage analogy method to equivalently simulate box girder is studied in detail. The principles that how to divide the grillage, how to calculate the constants for longitudinal beams and transverse beams, and how to deal with the results gotten by grillage analogy in box girder bridges are analyzed systematically, and the reasonable principles are proposed.Based on the principle of grillage analogy method, the grillage finite models with different supporting forms are built to analyze their effects to curved girder bridges by MIDAS/Civil finite element software, which come to the conclusion that the change of supporting form has great impact on the torsion and has little influence on the longitudinal shear force and bending moment. This thesis puts forward three methods to reinforce the ability of anti-torsion of curved girder bridges, which are presetting support eccentricity, reducing torsional span length and increasing the distance of beam-end supportings. By the calculation of the curved girder bridges with different internal support eccentricities, this thesis also draws the conclusions that if the support eccentricity is suitable, the beam will not disengage from supportings, the inside supportings will not appear negative counterforce and the maximum and the minimum torsion can be approximately equale. At length, the thesis provides means of arranging the supportings to ensure that they can not only adapt to the force and deformation of curved girder bridges, but also guarantee for security and stability of the structures. The thesis also provides measures to adjust supportings under different construction temperatures in hope of giving some reference for the design of curved girder bridges as well as some similar practical projects.更多还原