Bond Behavior of GFRP Rebars in Reinforced Concrete Members under Flexure

A proper bond between reinforcement and concrete is key for an appropriate composite action of both materials in reinforced concrete structures. However, to-date limited studies exist on bond of fiber reinforced polymer (FRP) bars in concrete members under flexure. In this paper, the bond strength developed by FRP and steel rebars is evaluated and compared, by testing reinforced concrete beams under three point bending load. The investigation included 4 beams that were 183 cm long × 15 cm wide × 36 cm deep: two of them were reinforced with sand coated GFRP rebars, while steel was used to reinforce the other two. For each of the reinforcing systems, two different embedded lengths were tested: 30 db (380 mm) and 40 db (510 mm). The beams were tested under a 3-point-bending setup and they were monitored using several measuring devices: LVDTS, potentiometers and strain gauges. Preliminary results show that the GFRP rebars have lower bond capacity than the ones made of steel. Moreover, it was inferred that the embedded lengths suggested by actual code provisions for GFRP rebars are too conservative