Experimental Study on the Working Mechanism of Bond-Type Anchorages for CFRP Tendons with Surface and Metallic Ribs

Abstract

Bond-type anchorages with plain carbon fiber–reinforced polymer (CFRP) tendon, ribbed CFRP tendon, and CFRP tendon with metallic ribs were fabricated and tested. The contributions of chemical adhesion force, friction force, and bearing force of the surface ribs to the maximum pullout load of a bond-type anchorage with ribbed CFRP tendon were discussed. The influences of the metallic rib type, metallic rib number, and preloading force on the anchoring performance of a bond-type anchorage with CFRP tendon were also investigated. Finite-element simulation was also conducted to help study the working mechanism of wedge plug type ribs. Results show that bilinear and trilinear bond-slip models can characterize the bond performance of a bond-type anchorage with plain and ribbed CFRP tendon, respectively. In addition, bearing forces of surface ribs are limited due to the low shear strength of the CFRP material. However, metallic ribs can address this problem and promote the anchoring performance if the connection between the CFRP tendon and the metallic rib is reliable. A wedge plug type rib exerts a larger contact pressure on the surface of the CFRP tendon during the plugging and loading procedure compared with chip-type rib, making it more reliable than the chip-type rib. Moreover, preloading the wedge plug type rib after plugging eliminates the initial slip between the CFRP tendon and the metallic rib. This allows the wedge plug type rib to function sensitively under pullout load. Consequently, the bond between the CFRP tendon and the grout can work together with the friction between the CFRP tendon and the wedge plug type rib, and thus can avoid the “snap back” phenomenon in the pullout test.