大跨径钢桁架拱桥极限承载力影响因素分析

Analysis of Influencing Factors of Ultimate Carrying Capacity of Long Span Steel Truss Arch Bridge

钢桁架拱桥的跨越能力强、造型美观且表现力丰富,在地质条件良好的条件下,其是理想的大跨度桥梁选择方案。以主跨240m的某大桥为工程背景,运用有限元方法计算其极限承载力,根据结构的边界条件、活载布置方式、初始缺陷及横向风荷载等因素发生变化,探究这些因素变化对桥梁极限承载力的影响。分析结果表明:拱脚位置活载最不利布载工况时,桥梁的极限承载力下降明显达14.3%,设计时需要着重验算分析此工况;横向风速的变化与桥梁极限承载能力大小之间呈现非线性关系。

Due to the steel truss arch bridge has a better performance in crossing ability,shapings and expression,it become an ideal choice for the long-span bridge type under a good geological condition. In this study,a bridge with 240 meters main span is considered as the engineering background. The finite element method is conducted for the calcula-tion of ultimate strength in this bridge. Based on the changes of the boundary condition,live load arrangement,initial defect,and transverse wind-load on the structure,this study indicates the influences in bridge ultimate strength. The an-alyzed results show that, the ultimate strength of bridge shows a dramatic decrease and it reaches 14.5%,when the worst live-load contributes on the arch springing. For this reason,this working condition need to be carefully checked in the design process. Moreover, there is a nonlinear relationship can be observed between the velocity change of transverse wind and the value of the ultimate live-load.