Experimental Bond Performance of Fibre Reinforced Polymer Prestressed Concrete Elements

In pretensioned prestressed concrete elements, bond between reinforcement and concrete differs is fundamental for a safe design. The so-called Hoyer effect, produced by the lateral expansion of a material when subjected to load, increases the bond resistance, but it also increases the circumferential stresses and then, the risk of cracking due to the tendon expansion. The bond behaviour of FRP tendons has not been studied in depth. To study the bond performance of FRP tendons, and characterize the transfer and flexural development length, an experimental program was carried out. This program was based on a setup called ECADA developed for steel tendons by the Universidad Politécnica de Valencia. The test specimen represents the anchorage area of the tendon and the remaining part of the theoretical beam is substituted by an anchorage measurement access system that has the same rigidity of the replaced part. The test starts by prestressing from one side and after concreting, the prestressed force is released gradually, then the transfer length is measured. Afterwards, the tendon is pulled from the other side, and the total development length is determined iteratively by producing samples of different lengths. The results of the ECADA tests have indicated that the transfer lengths of the FRP tendons being studied lie within 100 and 300 mm.