Design recommendations for the strengthening of reinforced concrete beams with externally bonded composite plates

A design approach for strengthening reinforced concrete beams with externally bonded fibre reinforced polymer (FRP) laminates is proposed. The use of staggered FRP laminate bonding to the tension face of the beam is suggested as an economical design. The FRP development length suggested in the guidelines is adopted. It is recommended that the FRP U-shaped strips be mechanically anchored so as to increase the longitudinal FRP bond strength and enhance the beam’s shear strength. With this design method failure due to debonding of the FRP laminate to the beam soffit can be avoided by the incorporation of FRP U-side strips. Recommendations based on the idea of modified shear friction are also given.