内隐藏焊缝对N形方圆钢管节点受力性能影响

为研究N形方圆钢管搭接节点中被搭接管内隐藏部分和主管间焊接与否对节点受力性能的影响，设计制作了4个N形方主管圆支管搭接节点足尺试件进行极限承载力试验.试验结果表明：被搭接管受拉时，其内隐藏部分和主管间不焊将降低节点承载力，且搭接率越大，降低幅度越大.此外，内隐藏部分未焊接的节点均发生了焊缝断裂破坏.以试验为基础，建立了非线性有限元分析模型，对324个不同几何参数、支管不同轴力性质下内隐藏部分焊接与不焊接的N形方圆钢管搭接节点进行了有限元分析，研究表明：内隐藏部分未焊接对被搭接管受压的节点承载力影响较小，但对被搭接管受拉的节点极限承载力影响较大.针对实际工程中钢管桁架均为先组装再焊接导致内隐藏部分难以施焊的情况，给出了设计建议.
To study the influence of hidden weld between the overlapped brace and chord on mechanical properties of overlapped CHS-to-SHS N-joints, two partially overlapped specimens with hidden seam weld and two without hidden weld were tested under monotonic loading. The test results showed that when the overlapped brace was in tension, the absence of hidden weld reduced the bearing capacity of joints, and the increased overlapped ratio decreased the joint bearing capacity obviously. Furthermore, weld crack appeared for all specimens without the hidden weld. Based on the experimental results, a finite element model was generated and validated. Using this model, the effects of loading hierarchy reversal of the braces and the hidden seam weld were studied on the response of totally 324 overlapped CHS-to-SHS N-joints with different geometric parameters. It revealed that the absence of hidden weld had less influence on the bearing capacity of the through-brace-in-compression joints than that of through-brace-in-tension joint. In view of the fact that the steel hollow section truss was assembled first and then welded, design suggestions were given.