Simplified Modelling Strategy For Evaluating Failure Propagation In Reinforced Concrete Structures

[EN] The progressive collapse of reinforced concrete (RC) structures involves a series of complex loadresisting mechanisms, including flexural, arching and catenary actions, among others. A detailed model comprised of 3D-solid elements with refined mesh and complex material models is typically adopted to accurately simulate these phenomena in new or existing buildings. However, this approach is computationally expensive and unsuitable for practical applications, especially when dealing with large models of real buildings. This study proposes practical modelling strategies that balance the accuracy of an RC structural response to an initial failure with a practical method of preparing and analysing the models. The proposed modelling approaches include a) the PMM¿lumped hinge (based on the FEMA- 356 guideline), b) a modification to the FEMA hinge, and c) the fibre¿distributed hinge. Several progressive collapse tests from the literature were simulated on RC subassemblies with various boundary conditions and loading scenarios from the literature to systematically validate and compare the different approaches. The results revealed that the PMM-lumped approach cannot accurately simulate the structure¿s response under large deformation mode (catenary) where plastic hinges (yielding of reinforcement) are typically formed at a more extended region along the member. The present study suggests that the fibre-distributed hinge is the most suitable approach for simulating the progressive collapse of structures. This finding is pertinent (yet also alarming) as some new studies in the progressive collapse field still adopt the traditional PMM-hinge approach, which may eventually lead to invalid conclusions.