Flexural response of FRP-strengthened lightweight RC beams: hybrid bond efficiency of L?shape ribbed bars and NSM technique

Abstract This paper presents the results of an experimental study on employing near surface mounted (NSM) fiber-reinforced polymer (FRP) reinforcement technique, and L?shape ribbed bars, for flexural strengthening lightweight reinforced concrete (RC) beams. 18 RC beams including 14 four normal-weight were designed. The strengthened with glass (GFRP) bars carbon (CFRP) laminate in bending tests. Test parameters included: (1) different FRP materials (glass sheets), (2) longitudinal steel ratio, (3) type technique used (NSM or hybrid). ultimate tensile strength, deflection, compressive strain concrete, failure mode examined under four-point test. Results showed that strength all increased between 33 105% compared to control beam. CFRP mid-span region was 10% higher than at both ends, although former exhibited 28% lower deflection. deflection combined reinforcing GFRP 108% higher, respectively, those only. Hybrid a considerably ductility (up 170% increase deflection) other comparison ACI440-2R guidelines indicated reasonable conservative prediction code expression.