斜靠式拱桥侧倾失稳临界荷载解析解

Analytical solution of lateral buckling critical load for leaning-type arch bridges

以新型空间拱桥——斜靠式拱桥为研究对象,提出斜靠式拱桥发生侧倾失稳时主拱肋与稳定拱肋间横撑切向和径向受力模型,基于Ritz法,构造桥梁各主要构件的变形能、外力势能以及吊杆非保向力势,首次推导出斜靠式拱桥侧倾失稳临界荷载的解析解,并通过与有限元计算结果比较,验证该解析解计算公式的正确性。进一步分析稳定拱肋、吊杆非保向力、以及主拱肋与稳定拱肋间横撑对斜靠式拱桥侧倾失稳临界荷载的影响。研究结果表明:①增设稳定拱肋可使桥梁侧倾失稳临界荷载提高1.6～1.8倍左右,同时随着稳定拱肋倾角的增加,临界荷载呈增大趋势;②受吊杆非保向力以及桥面系的影响,桥梁侧倾失稳临界荷载可提高约3.5倍左右;③横撑的径向抗弯刚度对斜靠式拱桥侧向失稳临界荷载影响较大。

A new leaning-type arch bridge was studied. Both lateral and radial mechanical models of the transverse brace between the main arch rib and the stable arch rib were proposed, when lateral buckling occurs. Based on Ritz method, numerical model of the main members of leaning-type arch bridge for calculation of the deformation energy, external loading potential energy and non-directional load potential energy of the hangers were constructed, and an analytical solution of the lateral buckling critical load was derived. Comparing results with those obtained from FEM calculations, it was verified that the analytical solution presented in this paper is sufficiently accurate. The study indicate that ： 1 ） the lateral buckling critical load can be increased about 1.6 - 1.8 times by setting the stable arch ribs, and the critical load would increase with the increase of the inclination angle of the stable arch rib; 2） the critical load can be increased by 3.5 times due to the influence of the non-directional load of the hangers and bridge deck ; 3 ） the radial bending stiffness of transverse braces has great impact on the critical load.