Preventing the Progressive Collapse of Reinforced Concrete Buildings
In this paper, a new mitigation scheme is presented to prevent the progressive collapse of reinforced concrete buildings resulting from the potential failure of a column. The new scheme comprises of installing vertical cables along the columns and hanging at the top of the building to a hat braced steel frame to provide an alternate load path above the potential failed columns. This scheme has been initially proposed by [1,2]. The authors conducted two dimensional finite elements analysis to investigate the viability of the proposed new scheme in which they considered embedding the cables in the columns for the new buildings and connecting the cables at the ends of the beams for the existing buildings. In this paper, a three-dimensional finite element analysis is conducted to investigate the viability of the new mitigation scheme in which the effect of the out of plane (transverse) beams and the hat braced frame members as well as their imposed loadings are considered.
The investigations are conducted in conjunction with the alternate path method recommended in  in which different scenarios of the first floor columns failure are adopted and used for checking the performance of old buildings and in designing new buildings. In this study, a numerical investigation is undertaken for a ten-storey reinforced concrete building considering the progressive collapse performance of the building with and without applying the mitigation scheme. The commercial general purpose finite element software ANSYS 11.0  is used in the numerical investigation. In this study, the failure of the corner column is considered. The results of the investigation of the building model show that the new approach of using cables and a steel braced frame is efficient in absorbing the loss of a first floor column and resisting the progressive collapse of the building.