大跨度蝴蝶拱空间受力性能参数分析

Analysis of Space Mechanical Performance Parameters of Long-Span Butterfly Arch

以某蝴蝶拱桥为研究对象,采用有限元方法开展蝴蝶拱的空间受力性能研究,对比分析斜拱肋、直拱肋、有无副拱等不同结构体系对拱肋内力、挠度以及稳定性的影响,讨论拱肋倾角、主拱刚度、副拱刚度等关键参数对蝴蝶拱受力性能的影响程度与影响规律。结果表明:恒载和活载作用下,外倾式拱肋的主副拱拱脚面外弯矩和挠度均显著增大;去除副拱肋会显著增大主拱肋的轴力和拱肋挠度;拱肋倾斜与否对拱肋稳定性影响较小,副拱肋可一定程度提高拱肋稳定性。主副拱肋的内力和挠度均随着拱肋倾角的增大而增大,拱肋稳定性随着拱肋倾角的增大而减小,建议设计时拱肋倾角小于12°;主副拱刚度从0.50EI增大到1.25EI时,有利于结构受力,而从1.25EI增大至2.00EI时,对结构受力优化效果不明显。对于背景桥梁建议主拱和副拱的倾角为12°,主拱和副拱的刚度提高至原结构刚度的1.25倍,优化后主副拱肋挠度降幅约36%,效果良好。

There are significant differences between the structural form of butterfly arch bridges and general arch beam combination bridges,and there are currently no design standards for parameters of this type of bridge structure in existing design specifications.Therefore by taking a butterfly arch bridge project as an example,this work analyzes the difference between the static performance and stability between the butterfly arch bridge and the common arch beam combination system is also analyzed by finite element method for overall structural analysis.It also examines the impact and the influence degree and law of the change of different design parameters on the static performance and stability of the structure is analyzed as well.The results indicate that the lateral stability of the structure significantly decreases when the arch rib dip Angle is greater than 12°.The recommended arch rib dip angle should be set between 6°and 12°.When the stiffness of the main arch is increased from 0.5 times to 1.25 times the original stiffness,it is advantageous to optimize the stress of the structure.It is suggested that the stiffness of the main arch to 1.25 times its original stiffness.The influence of the secondary arch's stiffness change on the mechanical characteristics and stability of the structure is similar to that of the main arch,but the influence is less than that of the rib stiffness change of the main arch.It is suggested that the stiffness of the secondary arch should be increased to 1.25 times that of the original secondary arch.