Structural Behavior of RC Beam-Column Subassemblages under a Middle Column Removal Scenario

AbstractSix RC beam-column subassemblages, consisting of two single-bay beams, one middle joint, and two end column stubs, were quasi-statically tested under a middle column removal scenario. The tests were aimed at investigating whether there are alternate load paths that can mitigate progressive collapse. With adequate axial restraints, both compressive arch action (CAA) and catenary action could be mobilized, significantly increasing the structural resistance beyond the beam flexural capacity. The effects of the top and bottom reinforcement ratios at the joint interfaces and beam span-to-depth ratio on structural behavior were studied. The results show that CAA is more beneficial to subassemblages with a short span-to-depth ratio and a low reinforcement ratio, whereas catenary action is more favorable to subassemblages with a large span-to-depth ratio and a high reinforcement ratio, particularly the top reinforcement ratio. As the last defense mechanism to prevent structural collapse, the development o...