A Novel Technique for Strengthening Reinforced Concrete Shear-Deficient Members Using Fiber-Reinforced Polymer Rope as Near Surface Mounted Reinforcement

Reinforced Concrete (RC) structures subjected to earthquakes can suffer from shear failure, which is often characterized by the formation of critical diagonal cracks and abrupt partial or total collapse. Externally Bonded Fiber-Reinforced Polymer (EB-FRP) sheets and laminates have been a popular method for strengthening shear-vulnerable RC structures. However, typical frame RC structures with non-rectangular cross-sectional shapes prevent the complete wrapping of EB-FRPs around them and in the transverse direction as shear reinforcement. Thus, most RC beams with L- or T-shaped cross-sections are retrofitted using EB-FRPs on three sides of the beam’s web, where brittle debonding failures predominate. This paper addresses these challenges by investigating the effectiveness of using Near Surface Mounted (NSM) carbon FRP ropes as a shear-strengthening technique in various RC structural members with shear problems. The experimental program presented includes three large-scale T-shaped beams and two full-scale external beam-column joints. The carbon FRP ropes were installed in the shear span of the T-beams and in the beam-column joints. The experimental results showed that the proposed FRP-strengthening technique improved the RC member’s structural performance and even altered the beam’s failure mode from shear and brittle to flexural and ductile.