上海光源工程屋盖钢管节点平面外受弯性能试验研究

Experimental study on out-of-plane bending performance of tubular joints in steel roof for the Shanghai Synchrotron Radiation Facility

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。

Based on tests of six full-scale model joints under out-of-plane bending （OPB） loading, the failure modes, rigidity, ultimate capacity and stress distribution of CHS X-joints in steel roof for the Shanghai Synchrotron Radiation Facility were systematically investigated. Both the test results and the finite element analysis results indicate that the joints primarily failed by excessive plastic deformation of the chord and weld cracking under OPB moment. Deflection patterns of the chord and the brace have some effects on the ultimate capacity but not on the initial joint rigidity. It is found that the stiffness ratio of the connection to the brace member is a critical factor to classify this joint to be rigid or semi-rigid. Uneven stiffness distribution along the intersection field leads to a significant stress magnification at the top and bottom edge of the brace section close to the joint zone. Comparison of the measured joint resistance with strength predictions from design codes shows API formulae provide the best estimation on the OPB capacity of CHS X- joints.