主管灌混凝土平面X形圆钢管节点受压承载力试验研究

Experimental research on compressive capacity of concrete filled chord circular section X-joints

对6个不同截面几何参数主管中灌混凝土的平面X形圆钢管节点在支管轴向压力作用下的承载性能进行单调加载试验研究。描述了X形圆钢管混凝土节点破坏现象,给出了支管轴力-整体位移曲线、支管轴力-主管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对节点承载力和抗压刚度的影响进行分析。结果表明:节点初始抗压刚度随着β、γ的增大而提高,而τ对初始抗压刚度影响很小;所有节点试件主管测点都未进入塑性,均为支管根部冠点首先进入塑性,且直到破坏时折算应变一直保持最大;主管灌混凝土使钢管节点承载力明显提高。有限元计算结果与试验结果吻合较好。

To research the compressive capacity of concrete filled chord circular section X-joints under axial compression, six joint specimens with different geometry parameters were tested under axial compression in brace. The test procedure, joint failure phenomenon, axial compression in brace-global displacement curves, axial compression in brace-deformation of chord tube and strain distribution curves were presented in the paper. The effects of β, γ and τ on compressive capacity and stiffness of the concrete filled chord X-joints were also studied. Results of these tests show that as the values of β and γ increase, the compressive stiffness of joints increase accordingly. The value of τ has little effect on stiffness. The crown spot of brace first yields and its strain strength will stay at the maximum till failure. Spot of chord still keeps elastic, concrete of chord obviously improves the capacity of joints. The calculated capacity values of joints based on the full yielding of brace section are unsafe. There is a good agreement between the experimental and the finite element analysis results in terms of failure modes, capacity and stress contour plot.