Shear strengthening of RC beams with FRP composites

Shear strengthening is required when an RC beam is found deficient in shear, or when its shear capacity falls below its flexural capacity after flexural strengthening. A recent technique for the shear strengthening of RC beams is to provide additional FRP web reinforcement, commonly in the form of bonded external FRP strips/sheets. Over the last few years, a large amount of research has been conducted on this new strengthening technique, which has established its effectiveness and has led to a good understanding of the behaviuor and strength of such shear-strengthened beams. This paper presents a state-of-the-art review of existing research on this topic. The methods of strengthening are described first, followed by a summary of experimental observations of failure processes and modes. The accuracy of existing design provisions is examined next through comparisons with test results. Limitations of existing experimental and theoretical studies are also highlighted. While the paper is mainly concerned with externally bonded FRP for shear strengthening, the emergence of alternative FRP shear strengthening techniques, including near-surface-mounted FRP and prestressed CFRP straps, is also noted.