Progressive collapse is a standard failure pattern of steel frames, which researchers expect to analyze quantitatively. However, the existing resist progressive collapse analysis methods based on empirical or reliability theories make it challenging to give quantitative results. Based on the stressing state theory, this work attempts to reveal the phase transition loads during the progressive collapse process from a thermodynamic perspective. Firstly, a 1/3-scale 4-bay steel frame with CFST columns is selected as a case study and equated to a thermodynamic/complex system, and its deformation distribution is transformed into state variables. Matrices (Modes) and Hamiltonians (Characteristic parameters) are constructed to describe the steel frame's stressing state in part or overall. The approximate phase transition loads can be detected by applying the clustering analysis criterion. Further, the phase transition loads can be verified from the renormalization perspective by comparing the Test-based and FEM-based phase transition loads. The EPB points can be directly used as a design reference. In summary, this work reveals the stable phase transition loads of steel frames from the thermodynamic perspective for a case study. Also, it enriches the theory and methodology of thermodynamic-based structural failure studies.

中文翻译：

---

从热力学角度揭示钢管混凝土柱钢框架在连续倒塌过程中的相变


渐进式倒塌是钢框架的标准失效模式，研究人员希望对其进行定量分析。然而，现有的基于经验或可靠性理论的抗连续倒塌分析方法使得给出定量结果具有挑战性。该工作基于应力状态理论，试图从热力学角度揭示渐进塌陷过程中的相变载荷。首先，选择1/3比例的钢管混凝土柱四开间钢框架作为案例研究，将其等效为热力学/复杂系统，并将其变形分布转化为状态变量。构造矩阵（模态）和哈密顿量（特征参数）来描述钢框架部分或整体的受力状态。可以通过应用聚类分析标准来检测近似的相变载荷。此外，通过比较基于测试和基于 FEM 的相变载荷，可以从重整化的角度验证相变载荷。 EPB点可直接作为设计参考。总之，这项工作从热力学角度揭示了钢框架的稳定相变载荷的案例研究。此外，它还丰富了基于热力学的结构失效研究的理论和方法。