Innovative compound-type anchorage system for a large-diameter pultruded carbon/glass hybrid rod for bridge cable

Fiber reinforced polymer (FRP) composite rods are gradually applied in the bridge structures as the stay cable to replace the steel cables. The orthotropic properties of FRPs parallel and perpendicular to the fiber direction lead to a huge challenge in anchoring. In the present paper, a hybrid fiber reinforced polymer (HFRP) composite rod was developed as the bridge stay cable through the pultrusion technology with the diameter of 19 mm, including carbon fiber reinforced polymer core (CFC) and glass fiber reinforced polymer shell (GFS). The simplified mechanical model based on equilibrium, geometric and physical equations and finite element analysis were conducted to analyze the potential failure modes of anchoring HFRP rods. It can be observed that the shear failure of CFC/GFS interface of HFRP anchorage system resulted in a low anchorage bearing capacity. An innovative compound-type anchorage system through the mechanical extrusion and chemical bonding was proposed to provide the reliable anchorage bearing capacity for HFRP rods. It can be found that the stress distribution of compound-type anchorage system was uniform along the anchoring length. The tensile load was effectively transferred to the steel anchor by the extrusion and bonding between HFRP rods and steel wedge. The fatigue life of HFRP rods with the compound-type anchorage system increased 5.88-7.44 times relative to the mechanical anchorage system, and 42.4 times relative to the bonding-type anchorage system.