钢管混凝土系杆拱桥关键节点的受力行为

为研究钢管混凝土系杆拱桥关键节点的受力行为,以某钢管混凝土系杆拱桥为工程背景,采用有限元方法对其全过程非线性受力行为进行深入分析。首先,建立钢管混凝土拱桥整体模型,对其整体受力行为进行分析,提取系杆拱桥关键节点在设计荷载工况下的最不利内力情况;然后以力边界条件形式施加给节点三维精细有限元模型,对拱脚节点和拱肋吊装节点在设计荷载工况下进行应力分析,探讨2种节点在设计荷载工况下的受力行为;最后,考虑材料非线性行为,采用弧长法对2类节点极限承载力进行分析,探讨其承载非线性行为及安全储备。研究结果表明:这2种节点构造形式在设计荷载工况下均安全可靠,且具有较大的安全储备;拱脚节点区拱肋钢管与系梁上翼缘板相交处存在明显的应力集中现象,该处构造复杂,焊缝多,设计时应重点关注;吊装节点区下弦钢管径向刚度小,采用环向加劲肋加强后,对钢管刚度及承载力均有显著改善。

Mechanical Behaviors of Key Joints of Concrete-Filled Steel Tube Tied Arch Bridge

In order to study the mechanical behaviors of key joints of concrete-filled steel tube(CFST) tied arch bridge,the whole process of nonlinear mechanical behaviors of the key joints was analyzed by finite element method.First,the FEM model of the CFST arch bridge was established to analysis the global mechanical behaviors,and the most unfavorable internal forces of key joints of the tied arch bridge under design loads were extracted.Second,the extracted internal forces were applied to the spatial fine finite element model of joints,and the mechanical behaviors of arch foot joint and arch rib hoisting joint under design loads were analysed to discuss the mechanical behaviors of both kinds of joints under design loads.Finally,considered the nonlinear performance of material,the ultimate bearing capacities of two kinds of joint were calculated by using arc-length method to discuss the nonlinear bearing behaviors and security reserves.The results show that(1) Both kinds of joints are safe and reliable under design loads and have a great security reserves.(2) There existed obvious stress concentration in intersect between arch rib steel tube and tied beam’s top flange in arch foot joint.This field was complex constructed,contains more welds,and should be paid more attention in the design process.(3) The radial stiffness of bottom chord is weak in hoisting joint.After the bottom steel tube stiffened by circumferential stiffening ribs,both radial stiffness and bearing capacity were greatly advanced.