Load transfer mechanisms in CFRP ground anchors with multi-strap ends

An investigation of the load-transfer mechanism in carbon fiber-reinforced polymer (CFRP) ground anchors with multi-strap ends was conducted based on experimental and numerical studies of one- and two-strap anchors. Differences in the strap geometry, i.e. different curvature distributions and transitions from the rod to the strap cross section, and different strap numbers only influenced the local load transfer from the straps to the grout, but not the global pull-out behavior. At higher loads, frictional load transfer along the straps occurred only in the outer strap; the friction was not sensitive to confinement variations provided by different rock types. The load transfer at the strap division, however, was proportional to the confinement level. An empirical model was derived to predict the load transfer in multi-strap anchors and applied to design a new three-strap anchor with a targeted capacity of 2500 kN.