The effect of continuity reinforcement on the progression of collapse in reinforced concrete buildings

Research performed on the progressive collapse of reinforced concrete buildings has led to the development of several design approaches relying on sufficient continuity reinforcement to provide alternative load paths that can prevent collapse after the failure of single columns. However, there are very few works examining the possible contribution that continuity reinforcement could have in pulling down parts of a structure that would otherwise be unaffected after large initial failures. This article presents the findings of a study based on validated simulations of a prototype building using the Applied Element Method (AEM). The results reveal that a large amount of continuity reinforcement can indeed contribute to more failure propagation after very large initial failures by transmitting more unbalanced forces to columns. It is also demonstrated that localised reductions in continuity reinforcement can prevent failure propagation after large initial failures. In addition, it is shown that this can be achieved while still allowing alternative load paths to develop after single-column failure as required by current codes and guidelines.