Fatigue Behavior of UHPC Beams Prestressed with External CFRP Tendons

This paper presents an experimental investigation of the fatigue behavior of ultrahigh-performance concrete (UHPC) beams prestressed with external carbon fiber-reinforced polymer (CFRP) tendons. Seven T-shaped beams were tested, and the effects of the effective prestressing stress, partial prestressing ratio, and fatigue load level on the flexural behavior and stiffness were analyzed and presented. Overall, the CFRP tendon-anchor assembly exhibited excellent fatigue performance. All tested fully prestressed beams survived 2 million cycles in fatigue tests, and the variation in their flexural capacity was limited. The partially prestressed beam failed after approximately 97,200 cycles due to fatigue fracture of the internal reinforcement. After fracture of the tensile steel bars, the partially prestressed beam behaved similarly to the fully prestressed beam and sustained more than half of the flexural capacity after 2 million cycles. A higher effective prestressing stress was favorable for maintaining the stiffness of CFRP prestressed UHPC beams.