中承式钢管混凝土拱桥动力特性分析

Dynamic characteristics of half-through concrete-filled steel tubular arch bridges

中承式钢管混凝土拱桥结构的振动问题较为突出,因此,其结构动力特性引起广泛关注。基于收集到的158座国内已建成的中承式钢管混凝土拱桥的设计资料,统计分析该桥型的主要结构设计参数和构造特征,进行基准桥梁试设计。采用Midas Civil空间有限元分析软件,建立了有推力和无推力中承式钢管混凝土拱桥动力计算的基准有限元分析模型,分析比较其动力特性;并进一步探讨了无推力中承式钢管混凝土拱桥在矢跨比、宽跨比、主拱肋刚度、横撑布置方式、吊杆失效以及支座布置等参数变化时桥梁结构动力特性的改变。结果表明:大跨径中承式钢管混凝土拱桥具有密集高阶模态的特点,且桥面板、拱肋的耦合振动明显;对无推力中承式钢管混凝土拱桥,在常用取值范围内,主要设计参数对结构动力特性的影响较小,合理布置横撑及增大桥面宽度,可明显改善结构的横向稳定性。

The dynamic characteristics of half-through concrete-filled steel tubular( CFST) arch bridges attract broad attention due to its serious vibration problems. Statistical analysis of main design parameters and structural features of this type bridges was carried out based on design information of 158 half-through CFST arch bridges built in China,then two reference bridges were designed. The reference finite element( FE) models for half-through CFST arch bridges with thrust and those without thrust were built using Midas Civil software,then the dynamic characteristics of the two models were compared. A comprehensive parametric analysis for the dynamic characteristics of half-through CFST arch bridges without thrust was performed considering variation of rise-span ratio,aspect ratio,stiffness of arch-rib,transverse brace style,failure modes of suspenders and restriction conditions of supports. The results showed that a long-span half-through CFST arch bridge has features of dense high-order modes and obvious coupled vibration between arch rib and deck; for half-through CFST arch bridges without thrust,the main design parameters within the range of commonly used values have little influence on its dynamic characteristics; reasonable arrangement of transverse bracing and increase in width of bridge deck can significantly improve the lateral stability of structures.