复式钢管混凝土装配式连接节点抗震性能试验研究

Experimental Study on Seismic Behaviors of Prefabricated Connections for Composite Concrete-filled Steel Tubes

为研究复式钢管混凝土装配式连接节点的抗震性能,设计了5个复式钢管混凝土单边螺栓节点试件及1个穿心螺栓对比节点试件,进行了柱端固定轴压下水平往复加载试验,分析了T型件加肋、T型件翼缘厚度、梁柱线刚度比等对节点破坏形态、荷载-位移曲线、承载力、延性、耗能、刚度退化等抗震性能的影响。结果表明:复式钢管混凝土单边螺栓T型件连接节点滞回曲线饱满,变形耗能能力较强;相比T型件未加肋试件,加单肋的节点极限承载力提高39%,加双肋节点极限承载力提高44%;T型件翼缘厚度20 mm的节点比14 mm的极限承载力提高13%,且极限位移也相应提高;当梁柱线刚度比增大时,节点试件极限承载力和耗能能力均明显提高;单边螺栓可发挥复式钢管混凝土柱内层钢管单边锁紧优势,内钢管应变值较大但节点域无明显变形,节点传力可靠且结构整体性较好;对比穿心螺栓节点,单边螺栓节点初始刚度略小,极限承载力略有提高,二者等效黏滞阻尼系数基本相当,而节点变形能力及延性显著提高,说明单边螺栓装配式连接能较好地保证节点的稳定性和抗震性。

In order to study the seismic behaviors of prefabricated connections for composite concrete-filled steel tubes(CFST), five blind bolted joint specimens and one through-bolted joint specimen for composite CFST columns were designed. The horizontal cyclic loading test with end-column fixed was carried out to analyze the influences of ribs and flange thickness of T-plates, beam-to-column stiffness ratio on seismic behaviors including failure modes, load-displacement curves, bearing capacity, ductility, energy dissipation ability, and stiffness degradation etc. The results show that hysteresis loops are full and the energy dissipation ability is strong for blind bolted T-plate joints. Comparing with the joint without ribs on T-plates, the bearing capacity of the joint with single rib on each T-plate increases 39%, and that of the joint with double ribs on each T-plate increases 44%. The joint with 20 mm T-plate flange thickness can improve its bearing capacity by 13% than that with 14 mm T-plate flange thickness, and the ultimate displacement can also be improved. The bearing capacity and energy dissipation ability of the specimen with a large beam-to-column stiffness ratio are improved significantly. The blind bolted joints utilize the advantages of unilateral locking in an inner steel tube, and the inner steel tubes have large strain values, but there is no obvious deformation in the joint core. The joint’s force transmission is reliable and the structural integrity is good. Comparing with the through-bolted joint, the initial stiffness of blind bolted joint is slightly lower, and the ultimate bearing capacity is slightly increased. The equivalent viscous damping coefficients of the blind bolted joint and the through-bolted joint are basically the same, while the deformation ability and ductility of the blind bolted joint are significantly increased, indicating that prefabricated blind bolted joints can better guarantee the stability and seismic resistance.