Shear Strengthening of RC Beams Using NSM GFRP Bars or CFRP U-Wrap Sheets

Fiber-reinforced polymers (FRPs) have been in view for the past three decades due to their high strength-to-weight ratio and resistance to corrosion. They are widely used as sheets, externally adhered to re-inforced concrete (RC) beams to be strengthened in shear. Although this technique is common, FRP sheets are exposed during their service life to environmental factors. As such, near-surface mounted (NSM) FRP bars may be more favored in shear strengthening of RC beams. Thus, this work experimentally investigates the performance of RC beams strengthened in shear using NSM FRP bars. The experimental results are com-pared to provisions of ACI 440.2-08 for FRP laminates and to design procedures proposed by De Lorenzis and Nanni (2001) and Dias and Barros (2010) for NSM bars. The current investigation reveals that ACI 440.2-08 overestimate the shear capacity of strengthened beams for widely spaced FRP laminate; thus, an up-per limit on the spacing between the sheets should be included in the current provisions. On the other hand, De Lorenzis and Nanni model correctly predicts the capacity of beams strengthened in shear using NSM bar; however, this model still needs a limit on the minimum spacing between the NSM bars.