Test of friction loss for curved prestressed tendons

Prestressing design is more and more widely used in bridge structures, in which one of the very important issues is how to determine the prestressing loss. In comparison with the straight prestressed tendons, the friction loss between curved tendons and ducts accounts for a large proportion of all losses. The friction loss of varied curved configurations is tested and studied in this paper. The principle and procedure is introduced and the experimental results are analyzed. The loss value of tendons under each load level is obtained. Based on least square principle, the curvature friction coefficient and wobble friction coefficient are worked out according to the test data. The measured results are compared with theoretical values recommended in some Chinese and foreign codes. The conclusions would serve as a reference for similar engineering structures.