Quantification of the critical collapse displacement is important to establish the collapse-resistant design method for the steel frame under a column-removal scenario. In this paper, the critical collapse displacement of steel frames due to an interior column loss is studied. The Bai-Wierzbicki fracture model of steel is incorporated into ABAQUS via user subroutine, in which the effects of both stress triaxiality and Lode angle on the fracture strain of steel are considered. The effects of the depth, span, axial restraint and rotational restraint of the beam on its critical collapse displacement are studied. The relationships of the critical collapse displacement with the depth, span and boundary conditions of the beam are established. The reliability of the proposed method is validated against the test results. It is found that the ratio of the critical collapse displacement to the depth of the beam can be expressed as a linear function of the span-to-depth ratio of the beam. The rotational restraint of the beam mainly affects the transition stage of the resistance-displacement curve of the beam and it has limited effect on the critical collapse displacement of the beam. The axial restraint mainly affects the catenary stage of the resistance-displacement curve of the beam and when the axial stiffness ratio exceeds 0.01, the effect of the rotational restraint on the critical collapse displacement of the beam can be neglected.

临界倒塌位移的量化对于建立拆除柱情景下钢框架的抗倒塌设计方法具有重要意义。在本文中，研究了由于内部柱损失引起的钢框架的临界倒塌位移。通过用户子程序将Bai-Wierzbicki钢的断裂模型引入ABAQUS，其中考虑了应力三轴性和洛德角对钢断裂应变的影响。研究了梁的深度、跨度、轴向约束和转动约束对其临界倒塌位移的影响。建立了临界倒塌位移与梁的深度、跨度和边界条件的关系。根据测试结果验证了所提出方法的可靠性。发现临界倒塌位移与梁的深度之比可以表示为梁跨深比的线性函数。梁的转动约束主要影响梁的阻力-位移曲线的过渡阶段，对梁的临界倒塌位移影响有限。轴向约束主要影响梁的阻力-位移曲线的悬链线阶段，当轴向刚度比超过0.01时，旋转约束对梁临界倒塌位移的影响可以忽略不计。梁的转动约束主要影响梁的阻力-位移曲线的过渡阶段，对梁的临界倒塌位移影响有限。轴向约束主要影响梁的阻力-位移曲线的悬链线阶段，当轴向刚度比超过0.01时，旋转约束对梁临界倒塌位移的影响可以忽略不计。梁的转动约束主要影响梁的阻力-位移曲线的过渡阶段，对梁的临界倒塌位移影响有限。轴向约束主要影响梁的阻力-位移曲线的悬链线阶段，当轴向刚度比超过0.01时，旋转约束对梁临界倒塌位移的影响可以忽略不计。