Behavior of externally draped CFRP tendons in prestressed concrete bridges

Successful use of carbon fiber reinforced polymer (CFRP) tendons in prestressed concrete bridges can be achieved by combining bonded internal tendons with unbonded externally draped tendons. To examine this theory, four bridge models were tested under static, repeated (7 million cycles), and ultimate loads. Also, the combined effects of factors such as: (a) draping angle; (b) deviator diameter; (c) number of attached die-casts used to anchor the tendons; (d) presence of cushioning material between the deviator and the tendon; and (e) twist angle on the strength of the tendons were examined. It was concluded that the use of externally draped CFRP tendons in bridge construction improves ductility and forces the concrete to undergo inelastic deformation resulting in compression failure. It is also noted that increasing the deviator diameter and using cushioning material at the deviators minimize the reduction in the breaking force of the draped tendon.