Experimental and numerical investigation on flexural behavior of concrete beams strengthened by different NSM tendons

Abstract

To comprehensively study the flexural behavior of RC beams strengthened by means of near-surface mounted (NSM) technology, 142 simply supported concrete beams strengthened in flexure with a wide variety of NSM materials, including fiber reinforced polymers (FRPs) and metallic materials were collected from previous experimental studies. The effects of the material properties and number of NSM reinforcements on the failure modes of beams strengthened with the NSM system were analyzed. The enhancements in the load-bearing capacity, ductility, and energy consumption capacity of beams were discussed. By classifying the NSM strengthening materials into brittle reinforcement and ductile reinforcement, the results demonstrated that beams strengthened with brittle NSM reinforcement were prone to premature brittle failure modes, as beams strengthened with only one FRP tendon easily failed through rupture of FRP, and those with more than one tendon were prone to debonding failure. Whereas beams using ductile materials were more likely to fail in a ductile manner. A numerical analysis was performed to predict the maximum strength of beams strengthened with different materials and prestress levels. Conservative prediction was observed for beams that failed by concrete crushing, and overestimated prediction was observed for beams governed by debonding failure or rupture of NSM tendons.