Composites fiber reinforced polymer rebar for concrete structures

Fiber reinforced polymer (FRP) rebar is nonmetallic, non-corrosive, high-strength-and stiffness-to-weight ratios. Carbon FRP (CFRP) and hybrid FRP (HFRP) rebars are used in this research. The surface of FRP rebars is helically wound with fiber strands to improve the bond behavior between FRP rebar and concrete. The pull-out bond specimens consist of FRP rebar embedded in 100mm X 100mm X 200mm and 100mm X 100mm X 300mm concrete blocks. The pull-out test program involves two types of FRP rebars, two types of diameters, three types of concrete strengths and five types of bond lengths. The modes of failure of bond test consist of rib shearing off without any damage to the concrete and FRP rebar rupture. The bond strength decreases with the bond length and the diameter of FRP rebar. Concrete strength has no effect on the bond strength of FRP rebar. The FRP reinforced concrete beams are simply supported under third point static loading until failure. The load-deflection relationship is recorded during the test. The calculating model is presented for predicting the midspan deflection. Test results reveal that there is a good agreement between the prediction and recorded results, the bond behavior of HFRP rebar is superior to that of CFRP rebar.