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对4个双折线隔板贯通式箱型中柱-H型钢梁节点和1个常规节点进行了低周往复循环加载试验,基于考虑焊接缺陷和焊接残余应力的结构钢椭球面断裂模型及偶联的椭球面屈服模型的断裂机理分析,对比研究了双折线扩大头构造对隔板贯通式箱型中柱-H型钢梁节点破坏模式、延性、承载力、刚度退化和耗能性能的影响,揭示了隔板贯通式箱型中柱-H型钢梁节点在强震时断裂和屈服的演化规律。结果显示,常规节点在几何不连续的梁翼缘对接焊缝侧边脆断,节点塑性转角约为0.02rad,达不到FEMA要求的0.03rad。双折线扩大头型节点在隔板折线段内形成塑性铰,节点塑性转角达到0.03rad,承载力和耗能性能较常规节点分别提高10.1%~27.7%和65.5%~123.6%。双折线扩大头构造和梁翼缘对接焊缝移至远离节点区的措施,减缓了节点区的几何突变和应力集中,规避了节点区焊缝过于密集和焊接热影响区的交叉影响,防止了节点过早脆断。该文给出了双折线扩大头节点的构造设计建议。
Low-cycle reciprocating cyclic loading tests were carried out on four box-column type mid-column-H type steel beam joints and one conventional joint with double-decker diaphragms. Based on the fracture model of the structural steel ellipsoidal fracture considering welding defects and welding residual stresses, The fracture mechanism of the ellipsoid yield model is analyzed. The effect of the double-fold expansion head structure on the failure mode, ductility, bearing capacity, stiffness degradation and energy dissipation of the box-type mid-column-H beam is compared. , The evolution of fracture and yielding of the box-type mid-column-H type steel beam under strong earthquake was revealed. The results show that the conventional joints are brittle on the side edges of the butt welds with discontinuous geometrical discontinuities. The plastic hinge angles are about 0.02 rad, which can not reach 0.03 rad required by FEMA. The double knuckle expansion head node forms a plastic hinge in the broken line segment of the partition. The plastic corner of the knot reaches 0.03rad, and its bearing capacity and energy dissipation performance are increased by 10.1% -27.7% and 65.5% -123.6% respectively. The action of the double-fold line expansion head structure and the butt weld of the beam flange moving away from the node area mitigates the geometric mutation and stress concentration in the node area and avoids the cross effect of the over-dense weld bead and heat affected zone in the node area and prevents the node from passing Broken early brittle. In this paper, the design proposal of double-polyline expansion head node is given.