Capacity of reinforced concrete beams with minimum shear reinforcement strengthened with NSM CFRP rods

Abstract

The concept behind Fiber Reinforced Polymers (FRP) bars is to provide for structural engineers an efficient retrofitting and strengthening system, considering the benefit-cost valuation. Orthodox rehabilitation methods presented numerous weaknesses such as difficulty in application, time consuming and lack of durability. FRP bars can be used to strength in both flexural and shear, though extensive research investigated the flexural capacity of FRP bars in structures rehabilitation, research around its shear capacity is still limited and requires more investigation particularly that it’s showing promising results in terms of structural performance. Implementing FRP bars to retrofit in flexural or shear requires an adequate technique, the externally bonded reinforcement (EBR), Near-surface method (NSM) and Embedded through section (ETS) are of the most practical strengthening techniques. Suggested as the most efficient system for shear strengthening, NSM is adopted in our experimental program. The aim of this research is to study the shear behavior of reinforced concrete beams strengthened with NSM CFRP rods. Therefore, three full-scale rectangular RC beams were casted, which consists of a control beam containing no shear reinforcement and two others containing minimum ACI shear reinforcement requirement. Third beam strengthened in shear with FRP using the NSM method. The overall results showed that the dual action between transversal steel and CFRP rods did not increase CFRP contribution to shear resistance of the specimen, hence the NSM FRP shear contribution is not significant with the presence of transversal shear reinforcement.