【作者】 毕银博；

【导师】 梅葵花；

【作者基本信息】 长安大学 ， 桥梁与隧道工程， 2010， 硕士

【摘要】 在新世纪,超大跨径悬索桥的研究越来越受到桥梁设计者的重视,尤其是新材料在超大跨悬索桥中的应用研究。由于超大跨径悬索桥结构柔性大、几何非线性效应突出,使成桥状态的力学性能与抗风稳定性问题变得复杂,因此,开展有关这一领域的研究十分必要。本文就CFRP缆索悬索桥与钢缆索悬索桥的力学性能及抗风稳定性做基本的研究分析。首先,系统地阐述了悬索桥的计算理论,包括弹性理论和挠度理论,以及现阶段采用的有限位移理论和解析计算理论,并对比分析了后两个理论的优缺点,为悬索桥的力学性能分析提供了理论基础。其次,采用有限元法对比分析了主跨2000m、3000m级CFRP缆索悬索桥与钢缆索悬索桥及5000m级CFRP缆索悬索桥的静力性能,包括恒荷载、车辆荷载、温度荷载作用下的静力性能。CFRP缆索悬索桥在恒荷载作用下主缆张力、吊索索力均小于钢缆索悬索桥,但加劲梁弯矩略大；在汽车荷载作用下竖向位移和扭转角均大于钢缆索悬索桥,但变形量都不大,满足实际使用需求；温度作用对钢缆索悬索桥影响较大,对CFRP缆索悬索桥影响甚小,这是由两种材料线膨胀系数不同产生的结果。再次,采用有限元法对比分析了主跨2000m、3000m级CFRP缆索悬索桥与钢缆索悬索桥及5000m级CFRP缆索悬索桥的动力性能,包括结构的自振特性与自振频率。CFRP缆索悬索桥与钢缆索悬索桥的各阶振型形状相似,CFRP缆索悬索桥侧向振动基频略小于钢缆索悬索桥,竖向振动基频略大,扭转基频有明显提高,扭弯频率比明显占优,抗风稳定性较好。最后,本文还对提高超大跨径CFRP缆索悬索桥抗风稳定性的结构措施进行了初步研究,为进一步的风致振动、抗震等研究提供分析依据。通过建立不同缆索形式的结构模型,包括交叉吊索模型、空间主缆模型和索桁桥模型,对比分析了几种主要方案的抗风稳定性,得出一些具有一定参考价值的结论。更多还原

【Abstract】 In the new century, the study of super-span suspension bridge, in particular, the application of new materials in super-span suspension bridge, is attached the growing importance to designer. As super-span brige structure is flexible, its effects of geometric noulinear are become more obvious. The mechanics performance and wind stability are become more complex in the form of bridge, therefore it becomes essential to carry out the research in this field.The calculation theories of suspension bridges, including elastic theory and deflection theory, finite displacement theory and analytic calculation theory used presently are introduced systematically. Moreover, the merits and faults of the latter two methods are compared and analyzed, which provides theoretical basis for the analysis of static and dynamic characteristic of suspension bridges.The static performances of the 2000m-span,3000m-span suspension bridges with CFRP cables and steel cables and 5000m-span suspension bridge with CFRP cables are analyzed making use of the finite-element method, including under the action of dead load, vehicle load and temperature. The main cable tension and suspender force of CFRP cable suspension bridges are less than those of the steel cable suspension bridges, but the stiffening girder moment of the former is slightly larger than that of the later, when they are under the action of dead load. In the vertical load effect, the vertical displacement and torsion angle are greater than those of the steel cable suspension bridge, but the deformations are small, which can meet the actual demand. Temperature effect on steel cable suspension bridge is great, but it is very small on the CFRP cable suspension bridge, which is because that the linear expansion coefficients of two materials are different.The dynamic performances, including the natural vibration frequency and vibration modes of the 2000m-span,3000m-span suspension bridges with CFRP cables and steel cables and 5000m-span suspension bridge with CFRP cables are analyzed making use of the finite-element method. The fundamental vibration mode shapes of CFRP cable suspension bridges are similar to those of the steel cable suspension bridges. The lateral vibration frequencies of CFRP cable suspension bridges are slightly less than those of steel cable suspension bridges, but the vertical vibration fundamental frequencies of the former are slightly larger than those of the later. The torsional vibration fundamental frequencies of the former are significantly higher than those of the later, so the wind stability of the former is better.The preliminary study on structural measures of improving wind stability of super-span CFRP cable suspension bridge is carried out, which provides basis for further research such as wind-induced vibrations and seismic analysis. Different forms of structural models, including cross-cable model, spatial main cable model and cable truss bridge model are established. The wind stabilities of several major programs are compared and some conclusions which has a certain reference value are coincided.更多还原