Rigid-Plastic Model for Progressive Collapse Assessment of Composite Beam-Column Connection Subassembly under Internal Column Removal

Abstract

This paper investigates the progressive collapse behavior of composite beam-column connection subassembly under column removal scenarios. An analytical model is proposed based on the rigid-plastic assumptions, in which the plastic hinges and inelastic rotations are assumed to develop concentratedly at only the connection interfaces, whereas the remaining parts are rigid except for the axial shortening/lengthening deformation when subjected to compressive/tensile forces. The component-based joint model proposed by Eurocodes is utilized to approximate the axial and plastic moment resistances of composite beam-column connections. The method to determine the force-displacement relationship of each connection component is presented in detail, particularly for the concrete slab and profiled steel decking where the actual nonuniform stress distributions along the slab thickness and width are carefully considered. By comparing with the published test results of composite joints under respective hogging and sagging moment, the proposed rigid-plastic model is capable of predicting the progressive collapse behavior of composite beam-column connection subassembly with reasonable accuracy. Based on the verified model, a parametric study is conducted with focus on the effect of lateral restraint stiffness on the collapse-resisting capacity of composite beam-column connection subassembly under column removal scenarios.