When vertical load-bearing members of building structures are subjected to accidental loadings, such as an earthquake, fire or explosion, the remaining structure chiefly relies on the beam mechanism and catenary mechanism of the steel beam as the main resistance capacity, to prevent local or large-scale progressive collapse. This paper presents a three-dimensional finite element model of concrete-filled square steel tubular (CFST) column to steel beam joint with bolted–welded hybrid connection in a middle-column-removal scenario using ABAQUS software. The multi-scale modeling method was employed to calculate the collapse resistance and mechanism under vertical load. The vertical displacement and bearing capacity curve of the middle failure column was calculated and analyzed. The collapse mechanism and bearing capacity contribution of the steel beam tying in different directions are also discussed. Results indicate that the failure mechanism of the process includes the beam mechanism, the translation mechanism, the catenary mechanism and the failure stage. After the short-span steel beam had been destroyed, the long-span steel beam continued to provide collapse resistance capacity. To improve progressive collapse resistance, the CFST column to steel beam joint with welded haunch is proposed in this paper. Comparing the anti-collapse bearing capacity and failure characteristics of the joint with the welded haunch and common joint indicates that the anti-collapse capacity of the joint with welded haunch can be improved, and the research results can be referenced for engineering progressive collapse design.

当建筑结构的垂直承重构件承受地震，火灾或爆炸等意外载荷时，其余结构主要依靠钢梁的梁机构和悬链线作为主要抵抗力，以防止局部或局部受力。大规模逐步崩溃。本文介绍了使用ABAQUS软件在中柱拆除方案中用螺栓-焊接混合连接的方钢管混凝土（CFST）柱到钢梁节点的三维有限元模型。采用多尺度建模方法计算了竖向荷载作用下的抗倒塌能力和破坏机理。计算并分析了中间破坏柱的竖向位移和承载力曲线。还讨论了不同方向上钢梁绑扎的倒塌机理和承载力贡献。结果表明，该过程的失效机理包括梁机理，平移机理，悬链机理和失效阶段。短跨度钢梁被破坏后，大跨度钢梁继续提供抗倒塌能力。为了提高抗连续塌陷性，本文提出了CFST柱到具有焊接直角的钢梁节点。比较焊接节和普通接头的抗倒塌承载力和破坏特性，可以提高焊接节理的抗倒塌能力，其研究成果可为工程渐进倒塌设计提供参考。