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对箱型柱-H型钢梁常规节点进行了低周往复循环加载试验和基于椭球面断裂模型及耦联的椭球面屈服模型的数值模拟和断裂分析。结果显示:箱型柱对梁的强约束,使梁翼缘对接焊缝应力集中严重,裂纹起始于几何突变剧烈的对接焊缝侧边。箱型柱-H型钢梁常规节点呈脆性断裂,节点塑性转角达不到临时指南FEMA要求的0.03rad。以考虑焊接缺陷和焊接残余应力的结构钢椭球面断裂模型为判据,提出了梁翼缘扩大头和长槽孔箱型柱-H型钢梁节点构造,进行了低周往复循环加载试验和数值分析。结果表明:扩大头构造显著减缓了对接焊缝侧边的应力集中程度,长槽孔促使箱型柱-H型钢梁节点在梁削弱截面形成塑性铰。当对接焊缝扩大头和梁翼缘长槽孔构造参数适当时,箱型柱-H型钢梁节点的塑性转角可达到FEMA要求的0.03rad,承载力和常规节点相当。
The low-cycle cyclic loading test and the numerical simulation and fracture analysis based on the ellipsoid fracture model and the coupled ellipsoidal yield model were carried out for the conventional joints of box-type H beam. The results show that the strong constraint of the box-column to the beam causes serious stress concentration in the butt weld, and the crack starts from the side of the butt weld whose geometry mutation is severe. Box column-H beam regular node brittle fracture, the node plastic corner less than the provisional guideline FEMA required 0.03rad. Based on the fracture model of the structural steel ellipsoidal fracture considering the welding defects and the welding residual stresses, the node structure of the box-column beam with H-beam flange and the long groove box are proposed, and cyclic loading test and numerical analysis . The results show that the enlarged head structure significantly reduces the stress concentration on the side of the butt weld, and the long slot facilitates the formation of plastic hinges in the weakening section of the box-H beam. The plastic corner of the box-type H-beam can reach the required FEMrad of 0.03rad, and its bearing capacity is comparable to that of the conventional joints when the structural parameters of the widened head and the flanged long slot of the butt weld are proper.