Experimental investigation of a bond-type anchorage system for multiple FRP tendons

This paper presents a bond-type anchorage system for multi-rod CFRP (Carbon Fiber-Reinforced Polymer) tendons with a bonding medium of ultra-high performance RPC (Reactive Powder Concrete). A full-scale specimen of the CFRP tendon-anchorage assembly GA12-9 for nine 12.6-mm-diameter CFRP rods was made, and its behavior was studied extensively through tensile tests. During the tests, the load distribution among the rods in tendon was monitored until the bonds of the multi-rod system failed. The test results showed that the capacity reduction resulting from inherent non-uniformities in multi-rod anchoring systems should be considered, and the corresponding capacity reduction factor has been provided. Furthermore, the equations for evaluating the bond strength and critical bond length of either single or multiple CFRP rods embedded in RPC grout were established and shown to be in good accordance with the test results. For a CFRP rod with a wrapped surface and tensile strength of 2300 MPa, a bond length of 25 times the rod diameter ensures that a tendon of 9 rods with clear spaces among rods of not less than a rod diameter can be anchored in a RPC medium of 130 MPa.