Progressive Collapse Assessment of the Steel Moment-frame with Composite Floor Slabs Based on Membrane Action and Energy Equilibrium

Background and Objective: Progressive collapse resistance of the steel moment-frame with composite floor slabs can be assessed by sudden column loss scenarios. In order to investigate the progressive collapse-resistant capacity of the steel moment-frame with composite floor slabs, a simplified approach based on the theory of membrane action and energy equilibrium principle is presented, which assessed the behaviour of progressive collapse resistance of this frame subjected to the removal of a penultimate column via the static and dynamic analysis. Mateial and Method: The residual vertical bearing capacity model considering of the membrane action and tie force (TF) method of composite floor slabs is developed to evaluate the force mechanism of the composite floor slabs. An energy-based theoretical framework is proposed for calculating the maximum allowable dynamic demands based on the nonlinear static Pulldown analysis, which is used to explore the relationship between of dynamic and static response in the progressive collapse process. Furthermore, the finite element software SAP2000 is used to calculate the numerical example to verify the reliability of this simplified approach. Results: The results show that the composite floor slabs significantly improve the structural progressive collapse-resistant ability and this simplified approach evaluates the progressive collapse resistance of the whole structure effectively. Conclusion: The existence of the floor can increase the ductility of the structure, and increase the progressive collapse-resistant ability. The appropriate value of the DIF depends on the ductility and amount of inelastic action the structure would experience during the column removal scenario.