Improving the robustness of reinforced concrete framed structures under sudden column losses

Recent guidelines have addressed provisions to improve structure integrity to accommodate progressive collapse due to failure of an interior support. This article presents novel technique and numerical model to enhance and evaluate reinforced concrete frame robustness to progressive collapse triggered by an interior or edge column failure in any floor. The presented technique enhances the structure robustness to progressive collapse by providing sufficient ductility, continuity, and redundancy. The technique involves placing external unbounded steel cables attached to the continuous beam in each floor at anchorage and deviator locations to bridge over a damaged column of any floor of the frame. The cables transfer the loads above the failed column to the anchorages and deviators that are assumed to perform as rigid arms, which in turn redistribute the loads to adjacent columns. The numerical model computes the frame building progressive collapse robustness using push-down analysis to simulate a column elimination and estimate the effects of cable catenary action on the frame. Two-dimensional reinforced concrete frame of six stories and four bays was adopted in the study. The numerical results demonstrate the prospect of resisting progressive collapse of reinforced concrete structures by implementing the presented technique.