Investigation of critical diagonal crack debonding in plated RC beams

Retrofitting of RC structures by adhesive bonding plates to their surfaces has been found through application, and experience in industry to be highly effective, inexpensive, unobstructive and efficient form of strengthening, stiffening and upgrading the structures. The paper presents fourteen (14) test results on reinforced concrete (RC) beams bonded with tension face plates, inclined plates and side plates to determine the critical diagonal crack (CDC) debonding strength using different types of plates, i.e., carbon FRP, glass FRP and steel plate in the presence or otherwise absence of the internal shear stirrups. The elastic modulus and ultimate tensile strength of the plates of different materials vary between 28–300 GPa and 300–2800 MPa, respectively. Tests show that the critical diagonal crack debonding may not occur at the formation of the critical diagonal crack in the beams that are provided with large amount of longitudinal reinforcement and transverse reinforcement, as it does with beams with less reinforcement. The analytical procedures adopted in this study are capable of predicting the CDC debonding strength of the plated beams with very good accuracy, and are validated with large number of test results taken from the published literature.