Evaluation of aramid and carbon fibre reinforced polymer composite tendons for prestressed ground anchors

Abstract

This paper presents the tension and bond properties of commercially available Aramid fibre reinforced polymer (AFRP) and carbon fibre reinforced polymer (CFRP) rods and their uplift and sustained loading behaviour as ground anchor tendons. Variables for the tests were tendon type and constituent, grout type, and bond or fixed anchor length. Test results indicated that the tension properties of fibre reinforced polymer (FRP) rods were close to the reported data. The surface geometry of FRP rods and the properties of filling grouts influenced the pullout behaviour and bond strength of grouted FRP rods. CFRP Carbon Fiber Composite Cable and Leadline anchors had a higher uplift capacity but lower creep displacement than AFRP Arapree and Technora anchors. The tested CFRP monorod and FRP multirod anchors with a 1000 mm fixed anchor length exhibited an acceptable uplift behaviour according to existing codes. Creep behaviour appeared to control the long-term uplift capacity of prestressed FRP ground anchors. The recommended working load for post-tensioned FRP ground anchors is 0.40 fpu for AFRP rods and 0.50fpu for CFRP rods, where fpu is the ultimate load or strength of the anchor tendon.Key words: FRP, tendon, bond stress, anchorage, grouted anchor, fixed anchor length, free anchor length, slip, creep.