自锚式悬索桥与上承式拱桥组合体系桥梁稳定性研究

自锚式悬索桥与上承式拱桥组合体系桥梁具有结构体系新颖、造型美观等特点,但由于这种结构形式尚未修建过,对其结构稳定性能进行研究具有重要的工程意义。在详细阐述结构恒载状态分析和活载传递机理的基础上,采用通用有限元软件ANSYS,分6种荷载工况对某座主跨406 m的组合体系方案作线弹性稳定、几何非线性稳定及考虑几何材料双重非线性极限承载力的分析,并探讨了初始缺陷对极限承载力的影响。通过与同等跨度的上承式拱桥作对比分析,得出两种桥型在稳定性方面的异同。分析表明:两种结构体系的一阶线弹性屈曲失稳模态均表现为中跨拱梁结合段的横向侧弯;不同加载模式对结构整体稳定性和破坏模式有一定影响;准确分析极限承载力需同时考虑几何、材料双重非线性的影响;面外初始缺陷对组合体系的极限承载力不会产生较大影响。

Stability Study of Self-Anchored and Arch-Suspension Combination Bridge

The self-anchored arch-suspension bridge is characterized by innovative structure and beautiful shape.It has great engineering significance to research on the stability of this structure that has never been built.Firstly,the dead load state and the transfer mechanism of live load were introduced in detail.Secondly,based on a self-anchored arch-suspension bridge scheme with a main span of 406 m,the universal finite element software ANSYS was adopted to study the linear elastic stability,geometrically nonlinear stability and double-nonlinear ultimate load-bearing capacity under six load cases.Also,the influence of the initial imperfection on the structure was discussed.Finally,for comparison,the deck arch bridge with the same span was studied to find out the differences of the stability between these two structures.The results show that the first-order linear elastic instability modes are both lateral flexure of the junction at mid-span for these two structures.And the load applied on the structure has a certain influence on the overall stability and failure mode.In order to analyze the ultimate load-bearing capacity accurately,the geometric and material nonlinearities need to be taken into account.At the same time,the out-of-plane initial imperfection has little influence on the ultimate load-bearing capacity for the self-anchored arch-suspension bridge.