Near-Surface-Mounted CFRP for Strengthening Concavely Curved Soffit RC Beams: Experimental and Analytical Investigation

Near-surface-mounted (NSM) carbon fiber-reinforced polymers (CFRPs) have emerged as a promising strengthening technique to improve the flexural performance of reinforced-concrete (RC) structures. Although these systems have been investigated extensively for flat soffit RC beams, their performance when applied to concavely curved soffit members requires investigation. This paper presents the results of an experimental program conducted to investigate the behavior of concavely curved soffit RC beams strengthened in flexure with NSM CFRP rods. Twenty RC beams were designed, fabricated, and statically tested, including 15 beams that contained curved soffits with varying degrees of curvature ranging between 5 to 20 mm/m. The remaining five beams were flat soffit and were used as control beams. The ultimate capacity, failure mode, flexural stiffness, ductility, and level of FRP strain prior to debonding of these beams are analyzed and discussed. This study identifies gaps in existing design guidelines and codes and presents recommendations for designers on NSM technology.