基于灰色关联理论的下承式外倾钢管拱桥稳定性分析

Stability Analysis of Through Steel Tube Arch Bridge with Extraversive Rib based on Grey Correlation Analysis

为分析结构参数对下承式外倾钢管拱桥稳定性的影响,以沙颍河桥为工程背景,利用Midas/Civil有限元软件建立计算模型,分析拱肋厚度、矢跨比、横撑形式、拱肋外倾角度等参数变化对其稳定性的影响,并用灰色关联理论揭示各参数变化对结构稳定性影响的关联程度。结果表明,结构失稳一般表现为面外失稳,矢跨比、拱肋厚度对全桥的稳定性影响较大;当矢跨比处于1/3.5~1/4时,结构的稳定性最高;拱肋厚度超过25 mm后,通过增加拱肋厚度的方式并不能明显提高结构的稳定性;与其他横撑形式相比,“X”形横撑提高结构稳定性效果最佳;增大拱肋外倾角度能在一定程度上提高结构的稳定性,但当拱肋外倾角度超过15°时结构的稳定性开始降低;为提高下承式外倾拱桥的稳定性,可优先选择对拱肋厚度进行优化。本文的研究可为外倾钢管拱桥的设计优化提供参考。

In order to analyze the influence of structural parameters on the stability of through steel tube arch bridge with extraversive rib,a finite element model is established using Midas/Civil with the Shaying River Bridge as the engineering background.The effect of varying parameters such as arch rib thickness,rise-span ratio,cross bracing form and arch rib camber angle on the stability is analyzed,and the extent to which these varying parameters are related to the stability of structure is assessed via a grey correlation analysis.The results show that structural instability is generally manifested as out-of-plane instability,the rise-span ratio and arch rib thickness have a greater influence on the stability of the whole bridge.When the rise-span ratio is at 1/3.5 to 1/4,the stability of the whole bridge is the highest,after the arch rib thickness exceeds 25 mm,the stability of the structure cannot be improved significantly by increasing the arch rib thickness.Compared with other cross bracing forms,"X"shaped cross bracing has the best effect in improving the stability of the structure,and increasing the camber angle of the arch rib can improve the stability of the structure to a certain extent,but when the camber angle of the arch rib exceeds 15,the stability of the structure starts to decrease.To improve the stability of the structure,the optimization of the arch rib thickness can be preferred.The study can provide some reference for the design optimization of cambered steel tube arch bridge.