不锈钢工字形柱弱轴端板连接节点受力性能试验研究

Experimental Study of the Structural Behavior of the Stainless Steel End-Plate Minor-Axis Joint of an I-Section Column

为探究不锈钢工字形柱弱轴端板连接节点的静力性能和抗震性能,开展了4个不锈钢弱轴边柱节点的单调静力加载和低周反复加载试验研究,其中奥氏体型和双相型不锈钢节点各2个.分别得到了节点试件在单调静力和低周反复荷载作用下的失效破坏形态、荷载-位移曲线以及螺栓力发展变化.结果表明:不锈钢弱轴边柱节点试件的静力试验曲线与骨架曲线较为接近,但随着循环次数和位移幅度的增加,出现损伤累积,骨架曲线的强度和延性出现下降.双相型不锈钢节点的初始刚度约为奥氏体型不锈钢节点的1.1倍,承载力约为后者的1.6~2.0倍,且累积耗能约为奥氏体型节点的2倍.静力荷载作用下,奥氏体型和双相型不锈钢节点试件的柱腹板受拉区域出现显著的塑性变形,且双相型不锈钢节点试件的螺栓头角部穿出柱腹板螺栓孔.低周反复荷载作用下,奥氏体型和双相型不锈钢节点试件的柱腹板横向加劲肋外侧焊趾处出现断裂破坏,滞回曲线存在明显捏拢现象以及不同程度的强度退化和刚度退化.此外,测得的节点转角满足现有规范限值,表明试验节点具有良好的变形性能.基于试验结果对现有普通钢梁柱弱轴节点计算公式的适用性进行了评估,结果表明现有普通钢弱轴节点计算公式低估了试验节点的初始转动刚度和受弯承载力.

The monotonic behavior and seismic performance of the stainless steel end-plate minor-axis joint of an I-section column were studied by performing static and cyclic loading tests on four stainless steel beam-to-exterior column minor-axis joints,including two austenitic stainless steel joint specimens and two duplex stainless steel counter-parts.Failure modes,load-displacement curves,and the bole force development of tested joints under static and cyclic loading conditions were determined.The obtained static test curves were in close agreement with skeleton curves,which exhibited degradation in strength and ductility due to damage accumulation associated with an increasing number of cycles and displacement amplitudes.The initial stiffness of the duplex stainless steel joint specimens was 1.1 times that of the austenitic specimens,and the ultimate resistance of the duplex joints was 1.6—2.0 times that of the latter.The cumulative dissipated energy of the duplex stainless steel joints was approximately twice that of the austenitic stainless steel counterparts.Significant plastic deformation in the tension zone of the column webs for both austenitic and duplex stainless steel joints under static loading was observed,and the pullout of bolt head corner was observed for the duplex stainless steel joint.The exterior weld toes of the transverse stiffeners of the column webs for joints under cyclic loading experienced fracture failure.The obtained hysteresis curve demonstrated apparent pinching phenomena and different levels of strength and stiffness degradation.In addition,the measured joint rotation capacity values of the tested joints met the existing specified limits,indicating that the tested joints displayed good deforma-tion property.Based on these experimental results,the applicability of existing formulae for carbon steel minor-axis joints was evaluated,which showed an underestimation of the initial rotational stiffness and moment resistance of the tested joints.