Experimental and theoretical study on the flexural behaviour of RC beams strengthened with externally bonded reinforcement on grooves CFRP laminates

This paper presents a study on the flexural capacity of Reinforced Concrete (RC) beams strengthened with Externally Bonded Reinforcement on Grooves (EBROG) Carbon Fibre Reinforced Polymer (CFRP) laminates. Thirteen single-shear tests and seven RC beams strengthened with CFRP are examined, comparing Externally Bonded Reinforcement (EBR) and EBROG techniques with different groove distributions. The results showed that EBROG improved the bond and flexural performance. Comparison with existing prediction models reveals that while the literature models accurately predict EBR results, they underestimated the bending capacity for EBROG due to calibration based on EBR bond parameters. Consequently, a numerical model is developed to simulate Intermediate Crack Debonding (ICD) for various bond-slip laws, applicable to the different strengthening techniques. The proposed model is validated using experimental flexural tests and calibrated bond-slip laws obtained from single-shear tests, demonstrating accurate prediction of ICD failure for both EBR and EBROG.