Effects of anchorage hardware on the cyclic tensile response of unbonded monostrands

This paper presents an investigation of the cyclic tensile response of monostrand-anchor systems, that is, unbonded monostrands including their anchorage hardware. Cyclic tensile testing was conducted for 0.5 in. (13 mm) and 0.6 in. (15 mm) diameter monostrand-anchor systems to fracture of all wires. All monostrands were Grade 270 (1860 MPa), cold-drawn, seven-wire, low-relaxation cables. Major findings of this experimental study include the following: premature failure of monostrand-anchor systems (for strains in the range of 1.5% to 4%) in the form of fracture of a single wire; successive fracture of monostrand wires (one at a time) with the applied extension, as opposed to the nearly simultaneous fracture of all wires in anchor-free monostrands; and differences between the loading and unloading/reloading stiffness of monostrand-anchor systems due to the seating and sliding of the wedges of the anchorage hardware. A numerical model was developed that is capable of capturing the basic characteristics of the observed experimental response. The numerical results are in good agreement with the experimental data.