变截面方钢管轻骨料混凝土柱-H钢梁隔板贯通节点抗震性能试验研究

通过对变截面方钢管轻骨料混凝土柱-H钢梁圆弧扩大头隔板贯通节点和基本型节点进行低周往复加载试验，分析了该类节点的破坏形态、滞回性能、延性、承载力、刚度退化与耗能能力等。结果表明：隔板圆弧扩大头节点先在隔板圆弧扩大区形成塑性铰，随后梁腹板焊接孔开裂，梁翼缘对接焊缝延性拉断；基本型节点在梁翼缘对接焊缝侧边开裂，裂纹扩展迅速至脆断；隔板圆弧扩大头构造明显提高了节点延性和耗能能力，有效降低了节点区焊缝过于密集和焊接热影响区的交叉影响，避免了梁翼缘对接焊缝处的应力集中和过早脆断；隔板圆弧扩大头节点的承载力、塑性转角和耗能能力较基本型节点分别提高16.09%~22.25%、17.34%~63.94%和24.97%~44.32%；加载到节点破坏时，节点域和柱内轻骨料混凝土未发生压碎、剥离、拉裂或滑移破坏，说明该类节点的抗震性能主要受钢梁与隔板间焊缝影响。

Experimental study on diaphragm-through joints of lightweight aggregate concrete-filled square steel tubular columns with variable cross section and H-section steel beams

Low-cycle reversed loading tests were performed on diaphragm-through joints with enlarged arc junctures of lightweight aggregate concrete-filled square steel tubular columns with variable cross sections and H-section steel beam and conventional joints. The failure modes, hysteretic behavior, ductility, bearing capacity, stiffness degradation and energy dissipation capacity of the joint were analyzed. The test results show that, for joints with enlarged arc junctures, plastic hinges form at the arc enlarged section of through diaphragms, and then cracks initiate at the edges of welding holes of beam webs, and butt weld of beam flanges ductile fracture at ultimate condition. The sharp changes in geometry and therefore stress concentration at butt weld of beam flanges in conventional joint can be eliminated by using the enlarged arc junctures. Butt weld of beam flanges are moved far away from panel zone and welding residual stress are mitigated in joints with enlarged arc junctures, and premature fracture of butt weld in conventional joint is avoided. The bearing capacity, plastic rotation and energy dissipation of joints with enlarged arc junctures increase by 16.09%~22.25%, 17.34%~63.94% and 24.97%~44.32% compared with those of conventional joint, respectively. The lightweight aggregate concrete filled in panel zone and square steel tubular columns is not crushed, peeling, cracking or slippage when joints are loaded at failure, which indicates that the seismic behavior of the tested joints is mainly dominated by butt weld of beam flanges.