论文部分内容阅读
对梁端轴向约束作用下平端板螺栓连接组合节点的抗火性能进行了试验研究。试验共设计制作四个试件,一个为梁端无轴向约束的组合节点抗火试验试件、两个为梁端受框架约束的组合节点抗火试验试件,另一个梁端无轴向约束的组合节点试件作为对比试件,进行常温下受力性能试验,以研究梁端轴向约束对组合节点耐火性能的影响。试验结果表明,常温下组合节点因柱腹板受压屈曲而破坏。火灾作用下组合节点温度场分布不均匀,组合节点均出现梁下翼缘屈曲,但二者在梁下翼缘屈曲后的受力行为不同。梁端无轴向约束组合节点在梁下翼缘屈曲后承载力迅速降低;而梁端有框架约束的组合节点在梁下翼缘屈曲后由于钢梁出现悬链线效应(在梁大挠度情况下,梁内轴力由压力转为拉力来承受竖向荷载),节点由压弯受力转为拉弯受力,表现出较好的承载能力和变形能力。试验反映了组合节点在结构中与梁的相互影响和共同作用,为理解火灾下组合节点在梁轴力影响下的结构反应、承载机理和破坏模式提供了依据。
The fire resistance of flat end-plate bolted joints under axial restraint on the beam end was studied. A total of four specimens were designed and manufactured. One was a joint fire test specimen with no axial restraint on the beam end. Two specimens were tested for the fire resistance of the combined joints restrained by the frame ends and the other beam end was free of axial Constrained composite node specimen as a comparative specimen, the stress performance test at room temperature was carried out to study the influence of the axial constraint on the fire resistance of the composite joints. The experimental results show that the joint at normal temperature is damaged by buckling of the column web. The distribution of temperature field in the composite joints under fire is not uniform, and the buckling of the lower flanges of the composite joints occurs under the action of fire, but the stress behavior of the two flanges after buckling is different. The bearing capacity of the beam without axial restraint joint buckling decreases rapidly after the buckling of the lower flange of the beam. However, the joint with restraint at the beam end has a catenary effect after bending under the beam flange , The axial force in the beam is converted from tension to tension to bear the vertical load), and the node turns from bending to bending, which shows better bearing capacity and deformation capacity. The experiment reflects the mutual effect and joint action of the composite joints with the beams in the structure, which provides a basis for understanding the structural response, bearing mechanism and failure modes of the composite joints under the influence of the beam axial force.