Transfer and development lengths of FRP prestressing tendons

An experimental investigation was conducted to determine the transfer length, development length and flexural behavior of fiber reinforced polymer (FRP) tendons in prestressed concrete beams. Three types of tendons were included in the study: carbon leadline, aramid technora, and a carbon fiber reference material. In addition, 12 control beams were pretensioned with a 7 wire steel strand (ST). The transfer length for FRP tendons was reasonably well predicted by the ACI design equation, with the modification in AASHTO providing for a minimum transfer length. The ACI equation predicts the development length conservatively provided the tendon stress at nominal capacity. The article proposes the modification of the ACI equation to account for the larger bond stress developed by the FRP tendons