The application of externally bonded fiber-reinforced polymer (EB-FRP) as shear transverse reinforcement applied in vulnerable reinforced concrete (RC) beams has been proved to be a promising strengthening technique. However, past studies revealed that the effectiveness of this method depends on how well the reinforcement is bonded to the concrete surface. Thus, although the application of EB-FRP wrapping around the perimeter of rectangular cross-sections leads to outstanding results, U-jacketing in shear-critical T-beams seems to undergo premature debonding failures resulting in significant reductions of the predictable strength. In this work, five shear-critical RC beams with T-shaped cross-section were constructed, strengthened and tested in four-point bending. Epoxy bonded carbon FRP (C-FRP) sheets were applied on the three sides and along the entire length of the shear-strengthened T-beams as external transverse reinforcement. Furthermore, the potential enhancement of the C-FRP sheets anchorage using bolted steel laminates has been examined. Test results indicated that although the C-FRP strengthened beams exhibited increased shear capacity, the brittle failure mode was not prevented due to the debonding of the FRP from the concrete surface. Nevertheless, the applied mechanical anchor of the C-FRP sheets delayed the debonding. Moreover, the design provisions of three different code standards (Greek Code of Interventions, Eurocode 8 and ACI Committee 440) concerning the shear capacity of T-shaped RC beams retrofitted with EB-FRP jackets or strips in U-jacketing configuration are investigated. The ability of these code standards to predict safe design estimations is checked against 165 test data from the current experimental project and data available in the literature.Strengthening of existing low-capacity RC structures using externally bonded fiber-reinforced polymers (EB-FRP) has become very popular because of the advantages of these materials such as their superior strength-to-weight ratio, their easy-to-apply character, their durability and their chemical and corrosion resistance [6][7][8]. For shear-critical RC elements with rectangular cross-sections in particular, full jacketing application of EB-FRP sheets wrapping around the cross-section and along their entire length provides increased strength and enhanced structural performance since it alters the shear brittle response to a ductile one [9][10][11][12]. However, common constructional limitations, such as the existence of a slab, usually prevent the wrapping of EB-FRP sheets around the cross-section. Thus, most RC beams with a T-shaped cross-section are shear strengthened using EB-FRP sheets (jackets or strips) on the three sides of the web of the beam (U-shaped retrofitting). A significant deficiency of this technique is the premature failure of the strengthened member due to the debonding of the EB-FRP at the adhesive composite and concrete interface [13][14][15][16][17][18][19][20].Several experimental studies have demonstrated the effectiveness...
