Assessment of current guideline formulations for flexural strengthening of reinforced concrete beams using NSM reinforcement

Near surface mounted (NSM) fiber reinforced polymer (FRP) reinforcement represents a valid alternative to externally bonded (EB) FRP reinforcement for strengthening existing reinforced concrete (RC) elements. When the NSM technique is employed for flexural strengthening, FRP composites are embedded into grooves cut into the concrete cover and filled with an inorganic or organic binding agent. Although many studies on the bond behavior of NSM FRP composites can be found in the literature, limited work is available regarding analytical models for designing NSM strengthening of RC members. In this paper, a database of experimental tests of 155 RC beams strengthened in flexure using NSM reinforcement is collected from the literature. The experimental results are employed to assess the accuracy of the analytical provisions obtained following the American, English, Canadian, and Italian guidelines