某钢框架栓-焊节点施工缺陷影响分析及处理

ANALYSIS AND REINFORCEMENT OF CONSTRUCTION DEFECTS OF BOLTED-WELDED JOINTS IN A STEEL FRAME STRUCTURE

对某钢框架结构的栓-焊节点焊接缺陷进行了调查,发现翼缘焊缝存在明显错台和未熔透现象。计算分析表明,焊缝错台高度低于板厚的20%时,对节点承载力影响不明显;超过板厚的20%后,翼缘的弹性拉压承载力会逐渐降低,错台达到板厚的70%时,承载力降低约20%。但是考虑地震时结构塑性变形,翼缘的受拉弹塑性承载力会显著降低,错台超过板厚1/3,受拉承载力降幅可达50%以上;翼缘的受压弹塑性承载力也有降低,但相对弹性承载力降低不显著。如果焊缝熔透深度不足,则翼缘的弹性和弹塑性拉压承载力都将显著降低。采用加劲肋对栓-焊节点进行补强,计算结果表明,采用该措施可以满足节点承载力要求。

The defects of bolt-welded joints of a steel frame structure were investigated.It was found that there were obvious staggered platforms and incomplete penetration in flange welds.The numerical analysis results showed that the bearing capacity of joints was not significantly influenced if the weld staggered platform was less than 20%of plate thickness.If the staggered platform exceeded 20%of plate thickness,the elastic tension and compression bearing capacity of flange decreased gradually,and the bearing capacity decreased about 20%when staggered platform was 70%of plate thickness.However,considering the plastic deformation of the structure during earthquake,the tensile elasto-plastic bearing capacity of flange was significantly reduced,and the decrease was over 50%when staggered platform exceeded 1/3 of plate thickness.The compressive plastic bearing capacity of flange also decreased,but not significant in comparison with elastic bearing capacity.If the penetration depth of the weld was insufficient,the elastic and elasto-plastic tension-compression bearing capacity of the flange would be all significantly decreased.It was suggested the bolt-welded joints should be strengthened by stiffening ribs.The analysis validated that such reinforcement could meet the bearing capacity requirements of the joints.