Numerical modelling of concrete beams reinforced with pre-stressed CFRP

In this paper, a numerical simulation is presented on the behaviour of concrete beams, reinforced with pre-stressed CFRP. The numerical results are compared to experimental results. Nonlinear material behaviour is considered, namely: the inelastic compressive concrete behaviour, the elasto-plastic behaviour of steel reinforced bars, the bond-slip relationship between the concrete and the internal steel reinforced bars, the mode-II fracture interface between the concrete and the pre-stressed CFRP and concrete cracking. Cracking in concrete is modelled according to a discrete crack approach: micro-cracking is assumed to localize at fictitious cracks with initial zero width. Two different approximations are adopted: (i) the fictitious cracks are embedded within the finite elements, giving rise to a discrete strong discontinuity formulation and (ii) main cracks, similar to the experimentally observed, are introduced, using interface elements, along the element boundaries, since the beginning of the analysis. A non-iterative sequentially-linear approach is adopted in order to avoid convergence problems. The aim of the present analysis is to try to better understand the failure mechanisms found in the experimental tests. Despite the complexity of the multiple nonlinear aspects of the behaviour of the structure, it is concluded that the numerical results are similar and are close to those observed experimentally.