Numerical and analytical studies on load-carrying mechanism of reinforced concrete beam-column structures against progressive collapse

From previous studies, catenary action was experimentally and numerically confirmed to provide beneficial effects on structures during load redistribution after a targeted column is notionally removed under an alternate load path procedure for progressive collapse mitigation. With the purpose to study the behaviour of reinforced concrete beam-column structures against progressive collapse, as well as to provide a simplified analytical model for predicting the development of catenary action, validated numerical models for quasi-static behaviour of sub-assemblages are employed in this paper. Extensive parametric studies are conducted to investigate the effects of important geometrical and material properties on catenary mechanism. The study shows that catenary action is less influenced by concrete strength and rotational stiffness of the boundaries. To provide a practical and yet accurate solution to predict the overall response of reinforced concrete sub-structures, a simplified model based on analysis results are proposed and validated by published test data. The model is shown to be able to reasonably capture the development of catenary action under different restraint stiffnesses and span-depth ratios.