A PROPOSED DESIGN EQUATION FOR THE DEVELOPMENT LENGTH OF FRP REBARS IN CONCRETE

摘要

Fibre reinforced polymer (FRP) rebars have been used as reinforcement in concrete structures in lieu of steel rebars due to their non-corrosive nature and high tensile strength. In order for the FRP rebars to develop their design strength, they should be anchored long enough in the concrete. The anchorage length depends primarily on the bond between the FRP and the concrete. This paper re-evaluates the factors that affect the FRP rebar-concrete bond namely: the type, surface texture and the embedment length of the of FRP rebars, the concrete cover, the concrete compressive strength and the confinement provided by the transverse reinforcement. The analysis showed that the type of fibre and the surface texture of the FRP rebars has no effect on the bond strength. On the other hand, increasing the concrete cover, concrete compressive strength and the confinement level would increase the bond strength. Based on the analysis an equation to calculate the development length was proposed. The equation is expected to result in 10% - 30% shorter development length for FRP rebars compared with the current ACI and CSA design requirements.