Time-dependent behaviour of concrete beams pretensioned by carbon fibre-reinforced polymers (CFRP) tendons

Due to its non-corrosive and high tensile strength properties, carbon fibre-reinforced polymers (CFRP) has attracted researchers’ interests worldwide to investigate the feasibility and effectiveness of using CFRP as reinforcements or prestressing tendons in concrete structures. However until now these studies have been mainly in the form of experimental tests and there is lack of theoretical framework provided. This paper first proposes an analytical method to predict the time-dependent behaviour, including concrete strains, curvature and deflection as well as loss of prestress, of concrete beams prestressed by CFRP tendons, under sustained service load condition. The paper then presents three illustrative examples of how to use this analytical method to calculate the time-dependent concrete strains, curvature and deflection of concrete beams pretensioned by CFRP tendons. It is concluded that the proposed theoretical framework is suitable for analysis of the time-dependent performance of the concrete beams pretensioned by CFRP tendons and the behaviour of such beams are comparable to those with steel and therefore CFRP can be effectively used as prestressing tendons in concrete beams.