Influence of the local bond stress distribution of FRP rebars on the anchorage in concrete

Poor durability of building structures leads to high repair costs. The durability of reinforced concrete structures is largely dependent on the corrosion resistance of the reinforcing steel. For applications which are highly endangered by corrosion, fibre-reinforced plastic (FRP) offer a solution. A basic prerequisite for the long-term functionality of a composite material is the bonding of the individual components. The lower modulus of elasticity and the different surface geometry of glass fibre- reinforced plastic (GFRP) reinforcement compared to steel reinforcement lead to a change in the bond stress distribution. This results in different bond splitting effects and load introduction lengths. In this paper, the bond stress distribution over the bond length of steel bars and FRP bars is compared. For this purpose, pull-out tests with short and long bond lengths are investigated. The force transmission from FRP to the concrete is measured by means of a fibre-optic measurement of pull-out tests with long bond lengths and compared with results from the literature.