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通过6个足尺模型节点的平面外弯曲加载试验,对上海光源工程屋盖结构中X型圆钢管节点的破坏形态、刚度、承载力及应力分布等进行了系统研究。试验和有限元分析结果表明,节点平面外弯曲失效主要表现为显著的主管塑性变形和焊缝断裂;主、支管弯曲方向对节点初始刚度影响不大,但对极限承载力有一定影响;节点刚度与支管线刚度的比值是判断节点刚性程度的关键指标;节点相贯线区域的不均匀刚度分布导致与其相邻的支管根部截面出现显著的边缘应力放大现象。基于极限变形限值确定的节点实测承载力与各国规范公式计算值的比较表明,API推荐的公式对X型钢管节点平面外抗弯强度提供了较准确的预测。
The failure modes, the stiffness, the bearing capacity and the stress distribution of the X-shaped steel pipe joints in the roof structure of Shanghai Light Source Project were systematically studied through the out-of-plane bending test of six full-scale model joints. The results of the test and the finite element analysis show that the out-of-plane bending failures of the joints mainly show significant plastic deformation and weld fracture. The bending direction of the main and branch pipes has little effect on the initial stiffness of the joints, but has some influence on the ultimate bearing capacity. And the ratio of branch line stiffness is the key index to determine the degree of node stiffness. The non-uniform stiffness distribution in the intersection of nodes leads to significant edge stress amplification in the root section of the adjacent branch. The comparison between the measured bearing capacity of the node and the calculated value of the national standard formula based on the limit deformation limit shows that the formulas recommended by the API provide a more accurate prediction of the out-of-plane flexural strength of the X-type steel pipe joints.