钢框架结构某根柱失效后，与失效柱相连的双跨梁对剩余结构的内力重分布和实现再平衡起到关键作用，而此时相邻双跨梁的线刚度对结构抗倒塌性能具有显著影响。以栓焊连接节点组合梁柱子结构拟静力试验结果作为校验，验证有限元建模方法的正确性。并建立了不同梁线刚度情形下的组合梁柱子结构足尺模型，重点分析了不同梁线刚度对组合梁柱子结构的内力发展和抗倒塌性能的影响。对目前基于变形的结构失效判定准则进行修正，基于该修正准则定量分析了双跨梁的梁机制抗力和悬链线机制抗力贡献水平，可为结构抗倒塌设计提供依据，对实际工程应用提供参考。分析结果表明：双跨梁的线刚度决定了梁机制抗力水平；而双跨梁的跨度决定了悬链线机制抗力水平，梁高对其影响较小，过大的梁线刚度不利于结构的位移发展。

When a column of a steel frame structure fails, the two-bay beams connected with the failed column play a key role in the internal force redistribution and re-equilibrium of the remaining structure, at that time, the beam line stiffness has a significant impact on the collapse resistance of the structure.The quasi-static test results of a composite beam-column substructure with rigid connections were used to verify the finite element modeling method.The full-scale model of the composite beam-column substructure with different beam line stiffness was established and the influence of beam line stiffness on the internal force development and collapse resistance of the composite beam-column substructure were emphatically analyzed.The current structural failure criterion based on deformation was modified, and on this basis, the contribution of the flexural mechanism and catenary mechanism resistances was quantitatively analysed, providing a basis for structural collapse resistance design and a reference for practical engineering application.The analysis results show that the linear stiffness of the two-bay beams determines the resistance level of the flexural mechanism, while the span of the two-bay beams determines the resistance level of the catenary mechanism.The beam height has little influence on it, and the excessive beam line stiffness is not conducive to the displacement development of the structure.