Detection of Damage in RC Beams Strengthened with NSM CFRP Rectangular Rod by Finite Element Modeling

The Near-Surface Mounted (NSM) reinforcement method has been shown to be one of the most important technique for the rehabilitation of damaged concrete structures or ones that are not adequate to support expected loads. However, despite decades of scientific research centered on the optimization of construction details, on models for bond behaviour and on design methods for flexural and shear strengthening, the effects of damage on FRP reinforcements have yet to be adequately investigated. In this work, the influence of different typology of damage such as loss of adhesion in the reinforcement-concrete interface, concrete’s cracking, and, finally, damages in FRP due to notches have been analysed by Finite Element Modeling (FEM). An incremental non linear analysis is developed using 3D Finite Element (FE) in the ANSYS code, considering both the static and dynamic behaviour of RC beams strengthened with one CFRP rectangular rod inserted into a groove according to NSM technique in relation to the different types of damage. Both progressive local failure and nonlinear stress–strain relationship of concrete are taken into account. For the CFRP, a model that takes into account the debonding phenomena at the interface between concrete-adhesive has been adopted. Finally, the developed theoretical model is calibrated and validated by comparison with results from experimentation and interesting aspects are remarked and discussed.