方钢管柱-H形梁栓焊混合连接节点抗连续性倒塌性能试验研究

Experimental investigation on progressive collapse behavior of WUF-B connections between SHS column and H beam

以2个方钢管柱-H形梁内隔板式刚性连接节点试件为研究对象,采用双半跨单柱型梁柱子结构,通过静力加载试验研究梁柱节点在中柱失效的连续性倒塌条件下的力学性能。试件梁柱节点采用栓焊混合连接方式,2个试件的腹板分别采用不同的螺栓排列形式。结果表明,试件的破坏均出现在节点区,发生于梁弦转角达到0.06 rad之后。最不利梁截面破坏时,首先发生下翼缘断裂,采用螺栓单列布置的试件发生下排螺栓孔壁局部承压与冲剪顺序破坏,而采用螺栓双列布置的试件发生剪切板内列螺孔处净截面开裂。梁柱子结构在加载前期主要通过受弯机制提供竖向抗力,在加载后期逐渐转变为依靠悬索机制抵抗上部荷载,且悬索机制最终可提供的竖向抗力高于前期受弯机制提供的竖向抗力。与梁柱节点采用腹板螺栓中部集中布置形式相比,腹板螺栓沿梁高度分散布置更利于梁翼缘开裂后剩余截面发展轴向拉力,可提高悬索机制竖向抗力与节点鲁棒性。

After the middle column is removed in a frame structure, effective tie force between the column and the beams is a critical issue for the remaining structure bridging over the failed column and realizing the load redistribution. To investigate the behavior of moment connections under the column removal scenario simulating the progressive collapse, two square tubular column-to-H beam connections with the inner-diaphragm in a beam-to-column assembly, including a beam-to-column connection with two half-span beams, were statically tested. The welded unreinforced flange-bolted web （WUF-B） connection was applied to connect the column and beams, with two different bolts-layouts at the web in two specimens. The results indicate that the failures occur at connecting zone when the beam chord rotations are greater than 0.06 rad. The beam section failure mode is initiated by the fracture of the bottom flange near the column, followed by different failure phenomena in two specimens. The lowest bolt hole of web plate failed with severe compression followed by the bolt tear-out failure near the access hole in specimen with one row of bolts, while in specimen with two rows of bolts the shear tab cracks at the section across the bolt holes inside. At beginning, the beam-to-column assemblies resist the upper load through the flexural mechanism, and with the increasing deformation the dominant force transfer mechanism is shifted to the catenary mechanism, which provides higher resistance in the later stage than that provided by flexural mechanism before. The WUF-B connections with bolts arranged along the depth of web are more efficient than those with bolts arranged near the middle part of web, for the remaining section developing axial tension after the bottom flange facture, and improve the catenary mechanism resistance and connection robustness.