A FEM-based model to study the behaviour of corroded RC beams shear-repaired by NSM CFRP rods technique

This paper presents the main features of a finite element FE numerical model developed using the computer code FEMIX to predict the contribution of near-surface mounted (NSM) carbon-fibre-reinforced polymer (CFRP) rods to the shear repair of corroded reinforced concrete RC beams. In the RC beams repaired in shear with the NSM technique, the CFRP rods are placed inside grooves pre-cut into the concrete cover of the RC beam’s lateral faces and are bonded to the concrete with high performance epoxy adhesive. Experimental and 3D numerical modelling results are presented here in terms of load–deflection curves and failure modes for 4 short corroded beams: two corroded beams (A1CL3-B and A1CL3-SB) and two control beams (A1T-B and A1T-SB), the beams noted B were repaired in bending only with NSM CFRP rods while those noted SB were repaired in both bending and shear with the NSM technique. The corrosion of the tensile steel bars and its effect on the shear capacity of the RC beams is discussed. Results show that the FE model is able to capture the main aspects of the experimental load–deflection curves of the RC beams. They also present the experimental failure modes and FE numerical modelling crack patterns, both of which gave similar results for non-shear repaired beams, which showed a diagonal tension mode of failure, and for shear-repaired beams, which failed due to a large flexural crack in the middle of the beams, along with the concrete crushing. Three-dimensional crack patterns were produced for shear-repaired beams in order to investigate the splitting cracks occurring at the middle of the beams and near the support.