箱形节点域不锈钢端板连接梁柱弱轴节点受力性能

为了探究不锈钢弱轴节点的静力性能和抗震性能,设计并加工了4个端板连接不锈钢梁柱弱轴节点试件,包括奥氏体型和双相型两种不锈钢牌号试件各2个,且均设置了箱形节点域进行加强。对节点试件分别开展单调静力和低周反复加载试验,得到了节点的整体受力性能和局部受力特征,包括节点在单调静力和低周反复荷载作用下的失效破坏形态、荷载–位移曲线和螺栓力发展过程,以及节点在低周反复荷载作用下的刚度、强度退化和耗能能力。结果表明：在静力和循环荷载作用下,节点的最终破坏形态为柱子蒙皮板与柱翼缘的对接焊缝均出现断裂,奥氏体型不锈钢节点的初始刚度约为双相型不锈钢节点的90%,塑性承载力约为后者的60%~70%。节点在循环荷载作用下,滞回曲线较为饱满无明显捏拢现象,出现了刚度和强度退化,奥氏体型不锈钢节点的累积耗能约为双相型不锈钢节点的3倍。设置箱形节点域之后,弱轴端板连接节点受力性能对焊缝质量要求更高,焊缝的提前断裂导致不锈钢材的优良延性未能充分发挥。采用有限元软件ABAQUS建立了精细数值模型对试验节点的受力性能进行模拟,并基于试验结果验证了所建立模型的准确性。得到的试验结果和建立的有限元模型可以为后续箱形节点域不锈钢弱轴节点受力性能研究提供参考。

Structural Behavior of Stainless Steel End-plate Beam-to-column Minor-axis Joints with Box Panel Zone

In order to explore the static and seismic performances of stainless steel beam-to-column minor-axis joints, a total of four stainless steel end-plate beam-to-column minor-axis joints were designed and fabricated, involving two austenitic stainless steel joint specimens and two duplex stainless steel counterparts, wherein which were reinforced with the box panel zone. Both monotonic and cyclic loading tests were conducted, and the structural behavior of joints and the characteristic of the local zone were obtained, including failure modes, load-displacement curves and bolt force development of joints under both static and cyclic loadings, as well as the stiffness and strength deterioration and energy dissipation capacity of joints under cyclic loading. The test results indicated that the butt welds between the skin plate and the column flange of the tested joints subject to both static and cyclic loading experienced fracture failure. The initial stiffness of austenitic stainless steel joint specimens was close to 90% of that of duplex ones, and the plastic resistance of austenitic joints was about 60%-70% of that of the latter. Hysteresis curves of joints under cyclic loading were relatively plump without noticeable pinching phenomenon, and the degradation of stiffness and strength was observed. The energy dissipation capacity of austenitic stainless steel joint was about three times that of duplex stainless steel counterpart. It was clear that the structural behavior of the beam-to-column minor-axis joints with box panel zone called for higher quality control of the welds, and it was the premature fracture of welds that undermined the full development of the excellent ductility of stainless steels. Meanwhile, elaborate finite element (FE) models were generated by means of the ABAQUS software package to simulate the structural behavior of the tested joints. The developed FE models were validated against the obtained test results. The obtained test results and developed FE models can be used for further studies on the structural behavior of stainless steel beam-to-column minor-axis joints with box panel zone.