Experimental Study on the Static and Fatigue Behaviour of a New Mechanical Wedge-Barrel Anchor

Post-tensioned steel strands have been traditionally used in different prestressed structures such as concrete girders, post-tensioned concrete slabs, cable-stayed bridges, post-tensioned walls, etc. for a long time. However, due to the vulnerability of steel to the fatigue and corrosion, application of carbon fiber reinforced polymer (CFRP) rods, because of their higher strength-to-weight ratio, corrosion and fatigue resistance, is a good substitution for prestressed steel strands. Nevertheless, it is a major challenge to develop a purely mechanical anchorage for CFRP rods. In this study, a new mechanical anchorage for prestressed CFRP rods is introduced. The proposed anchor consists of a steel barrel with a conical hole and three separate aluminum wedges being in direct contact with the CFRP rod. The anchor system transfers the load through friction, without any adhesive required. The static and fatigue behavior of the anchor were experimentally investigated, following the Guideline for European Technical Approval of Post-Tensioning Systems (ETAG 013). The effect of various parameters such as friction between the wedges and the barrel and between the wedges and the CFRP rod and the level of the presetting force on the static and fatigue performance of the anchors were experimentally studied. In the static tests, the load carrying capacity of the post-tensioned system was much higher than the guaranteed strength of the CFRP rods. The fatigue tests indicate that no slippage occurs between different components of the anchor system during the cyclic loadings, and, no damage is accumulated in the system after 2 million cycles. In addition, it was observed that the high frequency of cyclic loadings does not affect the cyclic performance of the system; i.e. under high loading frequencies, no heat was generated in the anchor, since the components did not have any relative movements.