TOWARD AN ECONOMIC DESIGN OF REINFORCED CONCRETE STRUCTURES AGAINST PROGRESSIVE COLLAPSE

A three-dimensional discrete crack model based on the Applied Element Method is used to perform economic design for reinforced concrete structures against progressive collapse. The model adopts fully nonlinear path-dependant constitutive models for concrete and reinforcing bars. The model applies a dynamic solver in which post-failure behavior, elements separation, falling and collision is predicted. First, the model is used to study the behavior of multi-storey reinforced concrete buildings designed in a traditional manner according to the ACI 318-08 and subjected to accidental removal of one or two central columns at the ground level. In an iterative way, the model is then used to investigate a safe design against progressive collapse for such extreme loading case. Based on the analytical results of the AEM, it can be concluded that the collapse of only one column would not lead to any progressive collapse of the studied reinforced concrete structure. However, the collapse of more than one column may lead to a progressive collapse of a considerable part of it. It is concluded also that the AEM could be successfully used as an analytical tool to suggest economical designs that are safe against progressive collapse of reinforced concrete structures.