Transfer bond stresses generated between FRP tendons and concrete

There is a growing interest in the use of new materials in construction. Materials such as fibre-reinforced plastics (FRPs) are lightweight, strong, and, for the most part, non-corrodible. Hence, the use of FRPs as prestressing tendons for concrete represents a viable, durable alternative to conventional practice using prestressing steel. This paper addresses the nature of the bond between an FRP tendon and concrete in the transfer zone of a pretensions concrete beam. In particular, two different types of aramid fibre-reinforced plastics (AFRPs) are considers. In the experimental investigation, the tendon pull-in behaviour during detensioning of a number of small-scale (100 X 200 X 2800 mm) pretensions concrete beams was monitored. These results were then used to make inferences about the bond stress distribution through the transfer zone. Both a constant and a non-linear relationship between the bond shear stress and the tendon slip were considers and the transfer behaviour of the two types of AFRP and steel were compared. It was found that by assuming a non-uniform bond stress distribution some interesting results about the distinctly different natures of the bond behaviour of the three materials were obtained.