Behavior of Precast Segmental Concrete Beams Prestressed with External Steel and CFRP Tendons

Precast segmental concrete beams (PSBs) prestressed with external tendons have become increasingly popular. This type of structure takes advantage of both the segmental construction method and the external prestressing technique. However, corrosion of steel tendons is still a great concern, which might increase the lifecycle costs of the structure. This study presents an experimental investigation into the use of carbon fiber–reinforced polymer (CFRP) tendons as an alternative to steel tendons for segmental concrete beams to mitigate the corrosion problems. To the best of the authors' knowledge, this is the first study using CFRP tendons to externally prestress segmental concrete beams. Four large-scale, T-shaped segmental concrete beams with different types of joints and tendon materials (steel/CFRP tendons) were built and cyclically tested under four-point loading. The test results show that CFRP tendons can replace steel tendons in segmental concrete beams as an external prestressing material. All the tested beams exhibited excellent performance regarding load-carrying capacity and ductility. The type of joint had an insignificant effect on the overall flexural behavior of the beams. After the joints opened, the beams with epoxy-coated joints behaved similarly to the beams with dry joints. The beams with CFRP tendons exhibited nonlinear behavior after the opening of joints; however, the level of nonlinearity was much less than that of the beams with steel tendons. Steel tendons achieved very high stresses at the ultimate stage, which were approximately 94% of their ultimate tensile strength. However, CFRP tendons ruptured at quite low stresses, which were approximately 78% of their nominal breaking strength on average. Finally, all the existing models examined in this study predict the tendon stress and the ultimate load of the beams with steel tendons well, but they encounter large scatter for the prediction of the tendons' stress and strength of the beams with CFRP tendons.