METHODS FOR ANALYZING LARGE SPIRAL STRANDS

Simplified routines are presented for obtaining useful information on the macroscopic level as regards the magnitude of interwire/interlayer deformations. Axial hysteresis is shown to vary considerably with the type of strand construction: parametric studies on various constructions covering a wide range of cable (and wire) diameters and lay angle have been used to obtain a simple method of estimating maximum hysteresis and the associated load range/mean ratio at which it occurs. A method has also been presented for obtaining the full-slip stiffness matrix as regards coupled extensional-torsional characteristics. In particular, it is found that unlike certain previously available theories, the present model predicts a (very nearly) symmetrical stiffness matrix which is in agreement with published experimental observations. Numerical examples are presented to facilitate the use of the present paper to forecast various aspects of the behaviour of other spiral strands. Practical implications of including the no-slip modulus as regards coupled extensional-torsional wave propagation in pre-tensioned straight cables have been briefly discussed.