Recovery Length in Multilayered Spiral Strands

An insight is given into the recovery length phenomenon in axially preloaded multilayered spiral strands. Recovery length is defined as the length measured from the fractured end of the wire, in which the wire will be able to carry its appropriate share of the axial load. Numerical results on realistic spiral strand constructions suggest that the recovery length in various layers is a weak function of the mean axial load on the cable. The lay angle has been found to be the primary parameter determining the magnitude of the recovery length of various layers in multilayered spiral strands and, hence, a straightforward method for determining variations of recovery length with lay angle in any layer of any spiral strand construction aimed at practicing engineers has been proposed. Using such estimates of recovery length, a minimum length of test specimens (for axial fatigue loading) equal to about 10 lay lengths is recommended for spiral strands.