Optimal Design Method and Experiment for Improved Wedge-Type Anchors of Large-Diameter Smooth CFRP Tendons

CFRP tendons with smooth surface conditions have good applicability in prestressed structures and structural reinforcement because of their high load-carrying capacity and simple production. However, they are difficult to anchor reliably. This paper developed an improved wedge-type anchor for large-diameter CFRP tendons. The mechanical behavior analysis theories of wedge-type anchors, including the load-carrying capacity evaluation model, were presented. The friction behavior of the sand-coated sleeve-tendon, which was used to evaluate the load-carrying capacity of the anchor, was experimentally investigated. The influence laws of the main wedge-type anchor parameters on the mechanical behavior of the anchor were obtained through theoretical analysis. Then, the optimal anchorage system design method was proposed, and the optimal anchor designs for smooth CFRP tendons with various diameters were presented. The anchor performance was experimentally evaluated, and the sleeve-tendon interface friction coefficient was approximately doubled after optimization, reaching 0.475. The wedge and barrel cone angles, preset load and anchor length had significant effects on the mechanical behavior of the anchor. The optimal design anchors for smooth CFRP tendons with diameters of 10 mm and 12.7 mm and spiral-wrapped CFRP tendons with diameters of 10 mm reached failure loads up to 93.8, 91.2 and 95.4% of the tensile capacity of the tendons, respectively.