朔准黄河桥极限承载力分析

研究目的:大跨度钢管混凝土拱桥以其特有的自重轻、强度大、抗变形能力强、施工方便和外形美观等优点,被大量地的用于桥梁结构中。本文以一座在建360 m钢管混凝土拱桥为例,采用通用程序ANSYS建立该桥的空间有限元计算模型,分别对该桥进行裸拱状态和考虑拱上建筑共同作用状态下的特征值屈曲稳定性分析、考虑几何和材料双重非线性的极限承载力分析,并对计算结果进行比较分析,给出拱桥极限桥承载力计算的一般性方法。研究结论:(1)考虑拱上结构的特征值屈曲分析结果最小值为13.477,裸拱的特征值屈曲分析结果最小值为6.673,均大于规范要求的4～5,拱肋截面满足面内和面外的稳定性要求;(2)拱桥极限承载力计算结果最小值为2.252,表明在双重非线性及结构初始缺陷的影响下,主力工况下,全桥结构的安全系数为2.252,满足考虑结构的非线性影响弹塑性稳定安全系数不得小于2的要求,结构设计合理;(3)拱上墩柱等拱上结构对全桥的计算刚度有较大的贡献,但对全桥的极限承载力影响较小;(4)特征值屈曲分析结果是非保守的计算结果,在实际结构设计过程中,必须考虑双重非线性及初始缺陷等对结构极限承载力的影响。

Analysis of Ultimate Bearing Capacity of Yellow River Bridge of Suozhou-Zhungeer Railway

Research purposes: The long span concrete filled steel tubular arch bridge is widely used because of its unique characters of light dead weight,big bearing capacity,good anti-deformation capacity,easy construction and nice appearance.In this paper,taking a concrete filled steel tubular arch bridge with a span of 360 meters as an example,a spacial finite element model was established with ANSYS to separately analyze the eigenvalue buckling stability of the bridge under joint effects of the bare arch and the architectures on it,and the ultimate bearing capacity on consideration of the nonlinearity of the geometry and material.The calculation result was compared and analyzed.The general method was presented for calculation of the ultimate bearing capacity of the arch bridge. Research conclusions:(1) On consideration of the structure on the arch,the minimum eigenvalue buckling in the analysis result was 13.477,and the eigenvalue buckling of the bare arch in the analysis result was 6.663.Both of them were bigger than 4 and 5 stipulated in the specification.The arch rib met the requirements of the stability inside and outside of the cross-section.(2) The minimum ultimate bearing capacity of the arch bridge in the analysis result was 2.252,and it showed that under the influences of the double nonlinearities and the initial defects of the structure,the safety factor of the bridge under main working conditions was 2.252,meeting the requirements of no less than 2 for the elastic-plastic stability safety factor on consideration of the nonlinear effects of the structure,and the structural design was reasonable.(3) The structures on the arch like the pier columns had the big effect on the stiffness of the bridge,while they had small impact on the ultimate bearing capacity of the arch.(4) The eigenvalue buckling in the analysis result was of a nonconservative calculation result.In the actual process of designing an arch bridge,the influences of the double nonlinearity and initial defects of the structure on the ultimate bearing capacity had to be considered.And the methods introduced in this paper could be as the reference to the similar works.