钢管混凝土拱桥拱肋模拟方法探讨与分析

Discussion and Analysis on Simulation Method of Arch Rib of Concrete-filled Steel Tube Arch Bridge

摘要:

为研究不同模拟方法对钢管混凝土拱桥拱肋的刚度取值和结构力学行为的影响，结合统一理论法与刚度叠加法的优点，按照统一理论双单元法的思路建模分析，根据GB 50923—2013和JTG/T D65-06—2015两本规范针对拱肋轴向刚度和抗弯刚度的差异，建立误差分析模型进行比较。并以净跨径390m中承式钢管混凝土拱桥为研究对象，分别基于统一理论法、统一理论双单元法和刚度叠加法建立有限元模型，探讨分析在恒载作用下不同模拟方法对钢管混凝土拱桥主拱轴力、位移和稳定性的影响。结果表明：通过统一理论法和刚度叠加法计算的刚度误差比较可检验钢管与混凝土的强度等级的匹配性，对于外径1.2 m的钢管混凝土，C60混凝土与Q345钢材的匹配性更优，且钢管壁厚为20~32 mm时最佳；主拱关键截面采用统一理论法、统一理论双单元法的轴力计算结果与刚度叠加法相比，相对差值均不超过5%；统一理论法模拟拱肋的整体刚度和稳定系数均大于刚度叠加法，是分析大跨钢管混凝土拱桥稳定的一种可靠、经济的方法。

Abstract:

In order to study the effects of different simulation methods on the stiffness value and structural mechanical behavior of CFST arch bridges, combined with the advantages of the unified theory method and the stiffness superposition method, according to the unified theory two-element method, a model is established for analysis. Based on two specifications of GB 50923—2013 and JTG/T D65-06—2015, aiming at the differences in the axial stiffness and bending stiffness of arch rib, an error analysis model is established for comparison. Taking the net span 390 m half-through CFST arch bridge as the research object, based on the unified theory method, the unified theory double-element method and the stiffness superposition method, the finite element model is established to discuss and analyze the influences of different simulation methods on the axial force, displacement and stability of the main arch of the CFST arch bridge. The results show that the comparison of the stiffness error calculated by the unified theory method and the stiffness superposition method can check the matching of the strength grades of the steel pipe and the concrete. For the CFST with an outer diameter of 1.2 m, the matching between the C60 concrete and the Q345 steel is better, and the wall thickness of the steel pipe is the best when 20~32 mm. Compared with the stiffness superposition method, the relative difference value of the axial force calculation results of the key section of the main arch using the unified theory method and the unified theory dual element method is not more than 5%. The overall stiffness and stability coefficient of the arch rib simulated by the unified theory method are larger than those by the stiffness superposition method, which is a reliable and economic method to analyze the stability of long-span CFST arch bridges.