Transfer and flexural bond performance of aramid and carbon FRP tendons

The use of non-corrosive fiber reinforced polymer (FRP) composite materials as reinforcement for concrete structures has been growing in recent years. This study, conducted at the Federal Highway Administration Laboratories, compared the transfer length and flexural bond behavior of five commercially available FRP tendons. Three of the tendons had aramid as the main reinforcement, and the other two included carbon fibers. Sixteen specimens, including a control specimen reinforced with a high strength steel tendon, were tested. It is shown that the transfer length for FRP tendons is generally shorter than that for steel. For the aramid tendons, the ACI equations result in a conservative estimation of the development length; however, this is not true for the carbon tendons examined. The efficiency of the various grips and the loss of prestress for each of the tendons is also discussed.