Abstract
To reduce the size of deviators in the external tendon systems, the bending radius of the external tendon at the deviators is normally designed to be smaller than that in the internal tendon systems. This practice raises concern about the fretting fatigue of tendons. In this study fretting test on S15.2 strands used as the external tendons in PC bridges were carried out. Rust due to fretting corrosion was observed at the starting point of the fatigue fracture on the strands surface. An S - N diagram for the strand in the deviator was derived from the fatigue tests, and it was confirmed that the fatigue life is shortened by fretting between strands.
