Validation of a discrete crack model for lightweight aggregate concrete beams

Abstract

The development of crack models capable of simulating the discrete nature of fracture is of interest to many different areas of research. For example, the structural analysis innovative designs now made possible by new ultra-high performance concrete mixtures would certainly benefit from such improved predictive capabilities. Currently, there are numerous numerical approaches available in the literature, for instance based on nodal or element enrichment techniques, or even on remeshing strategies. Typically, the validation of such approaches was achieved using benchmark tests that contained few cracks and where the overall displacements were compared until failure. Having this into account, this paper describes a detailed validation of a discrete crack model based on embedded discontinuities for predicting the behaviour of lightweight aggregate concrete. The model itself includes the rigid body movements associated with the opening of cracks and relies on a robust noniterative algorithm to overcome convergence difficulties typically found with numerous cracks and material non-linearities. Validation was achieved using experimental data from tests performed on lightweight concrete beams (LWAC) under flexural load, where displacements, curvatures and cracks width were properly monitored. This data include, not only overall displacements, but also the complex crack patterns produced during the tests. The model was shown to predict well the overall crack patterns and openings, and was used to perform extrapolations on crack widths for different reinforcement ratios.