钢管加劲焊接空心球节点的受压承载力分析

采用钢管加劲焊接空心球节点可以使拉索方便地穿过下弦节点，但加劲钢管的存在会影响节点不同方向的受压承载力，现行网架规程尚没有这类节点的受压承载力计算公式。为此，采用三节点及四节点壳单元并考虑钢材的多线性等向强化准则，对节点进行了大变形弹塑性有限元分析，跟踪了节点在轴向压力作用下的荷载位移曲线。通过4组节点的受压破坏试验，发现节点均为弹塑性压曲破坏；将试验值与数值解进行了比较，两者吻合得很好。在此基础上，提出了钢管加劲焊接空心球节点两个方向的受压承载力计算公式。

Compressive Load Capacity of the Welded Hollow Spherical Joint with Pipe Stiffener Under Axial Compressive Force

A new type of welded hollow spherical joint with pipe stiffener called WHS-PS was used in the pre-stressed steel-concrete grid structures and it could be passed easily by the cables in the bottom chord plane. The compressive load capacity was influenced by the pipe stiffener, but there was no listed formula to calculate the load capacity for the joint of WHS-PS. With 3-node and 4-node shell elements and in the consideration of the multi-linear isotropic hardening model, the elasto-plastic finite element analysis with large deformation was carried out. The equilibrium path under axial compre-ssive force was traced by the cylindrical arc length method. Through 4 model tests, it can be found that the collapse is elasto-plastic buckling failure under axial compre-ssive load and the capacity is related to the design strength of the material. The results of the experiments are well agreed with the numerical data. The formula is put forward to calculate the compressive load capacity in two directions and it is more reasonable than that listed in the national design specification.