RELAXATION, CREEP, AND FATIGUE BEHAVIOR OF CARBON FIBER REINFORCED PLASTIC TENDONS

Corrosion of steel tendons is a major problem in prestressed and posttensioned concrete structures. Fiber reinforced plastics (FRPs) are a promising alternative to steel because of their high tensile strength, light weight, and resistance to electrochemical corrosion. This paper presents the results of a preliminary study on the relaxation, creep, and fatigue behavior of two carbon fiber reinforced plastic tendons, namely, Leadline PC-D8 8-mm-(5/16 in)-diameter tendon and 1-by-7.75-mm (5/16-in) carbon fiber composite cable (CFCC) in air and in simulated aggressive environments. The loss of tensile force for the 3,000 hour test duration at stress ratios of 0.4 and 0.6 was generally less than 10%, and it depended primarily on the initial stress level and the type and temperature of the environment. Creep behavior of both tendons was good; however, the creep strains were higher in solutions than in air. Fatigue strength was generally good and depended on the stress range and initial stress level.