Fretting Fatigue in External Post-Tensioned Tendons

摘要

External post-tensioning tendons are frequently used in the construction ofmultiple-span box girder bridges. They occur particularly frequently in long bridges erected using span-by-span construction as in elevated urban freeways and over water viaducts. In addition, they have been successfully used in a number of bridge strengthening projects. The objectives of the study were to build and cyclically load tendons with concentrated angle changes representative of external tendons and typical deviator details. The specimens were to be examined for evidence of fretting fatigue. Recommendations for changes in design or construction techniques were to be made to reduce the potential for harmful fretting fatigue. No evidence of fretting fatigue worse than that found with internal post-tensioned tendons was found. A wide range of prestressed concrete fatigue applications was examined and a comprehensive design procedure for fatigue applications was suggested.