支管灌混凝土平面X形圆钢管节点轴压性能试验研究

为研究支管灌混凝土X形圆钢管节点的轴压性能，对6个不同截面几何参数的支管灌混凝土X形圆钢管节点进行了单调加载试验。介绍了节点试验方案，揭示了节点破坏模式，给出了加载点荷载 端位移曲线、支管轴力-主管壁变形曲线以及节点区域折算应变分布曲线，并将支主管外径比β、主管径厚比γ和支主管壁厚比τ对节点轴压承载力和弹性轴压刚度的影响进行了分析。试验研究结果表明：节点试件均表现出较好延性；所有试件的主管壁最大竖向变形位移都大于0.03倍主管直径，在判定该类圆钢管节点轴压承载力时应该采用极限变形准则；节点轴压承载力与弹性轴压刚度都随着β和τ的增加以及γ的减小而提高；所有试件的支管根部测点都未进入塑性且主管都是鞍点和冠点之间的中间测点首先进入塑性；在试验参数条件下，支管灌混凝土对X形圆钢管节点轴压承载力提高不明显，甚至会降低其轴压承载力。目前GB 50017-2003《钢结构设计规范》公式不能较好地计算支管灌混凝土X形圆钢管节点轴压承载力。

Experimental research on compressive behavior of circular section X-joints with concrete filled braces

To research the compressive behavior of circular section X-joints with concrete filled brace,six joint specimens with different geometric parameters were tested under axial compression in brace.The test procedure,joint failure modes,jack load versus global displacement curves,axial compression in brace versus deformation of chord tube and strain distribution curves were presented in the paper.The effects of β,γ and τ on compressive capacity and elastic compressive stiffness of circular section X-joints with concrete filled braces were also studied.Results of these tests show that the joints all show good ductility.The ultimate deformation of joints is all larger than multiply diameter of chord by 0.03.The ultimate deformation criterion can be adopted to evaluate the compressive capacity of the joints.As values of β and τ increase,value of γ decreases,accordingly capacity and elastic compressive stiffness of joints increase.Spots of brace still keep elastic while spots between crown and saddle of chord yield first.The concrete of brace not significantly improves the capacity of joints,even reduce the capacity of joints in certain geometric parameters.Equation of code for design of steel structure can’t calculate the compressive capacity of circular section X-joints with concrete filled braces.