钢管混凝土T形相贯节点应力集中系数研究

通过对钢管混凝土T形相贯节点的试验和有限元分析，研究了在轴向荷载和平面内弯矩作用下节点的应力集中系数。结果表明：轴向荷载作用下钢管相贯节点的应力集中系数分布不均匀，而钢管混凝土相贯节点分布较均匀，主管内填混凝土有效降低了相贯节点的应力集中系数，同时也将热点的位置由鞍点变为冠点；平面内弯矩作用下钢管相贯节点主管的应力集中系数分布不均匀，而钢管混凝土相贯节点主管分布较均匀，主管内填混凝土有效降低了主管的应力集中系数，两者支管相差不大；主管轴力对节点的应力集中系数影响较大，进行轴向压力和平面内弯矩作用下节点的应力集中系数计算时，应考虑到主管轴压比的影响；现行规范对于钢管相贯节点应力集中系数的计算公式并不适用于钢管混凝土相贯节点。基于强度等效的原则，提出了改进的应力集中系数计算公式，计算结果和试验结果吻合较好。

Study on stress concentration factor of concrete-filled steel tubular T-joints

The stress concentration factors (SCF) of concrete-filled steel tubular (CFST) T-joints subjected to axial loading and in-plane bending were studied by using test method and finite element analysis. The results show that, the SCF distribution along the weld toe of steel tubular joint is uneven when subjected to axial loading，while that of the CFST one is even, indicating that the SCF of CFST joint is reduced effectively by filling the chord with concrete. The position of hot spot is also changed from saddle point to crown point. The SCF distribution along the weld toe of chord of tubular joint is uneven when subjected to in-plane loading，while that of chord of CFST one is even, indicating that the SCF of the chord of CFST joint is reduced effectively by filling the chord with concrete. However the difference between the brace of steel tubular joint and CFST joint is not significant. The stress concentration factor of the joints could be affected by the chord axial force, so the chord axial compression ratio should be considered when considering the fatigue strength of the joints subjected to axial compression and in-plane bending. The SCF calculation formulas of the design standard for the tubular joints are not suitable for CFST joints. Finally, improved SCF formulas based on the principle of strength equivalence were proposed, and the calculated results agreed well with the test results.