SIMPLIFIED METHODS FOR ANALYSING STEEL STRANDS

The paper presents some design-office-type methods for large diameter and multilayered spiral strands with a minimum of equations and formulae. The proposed design methods are based on previously reported orthotropic sheet theory which, unlike previously published models, concentrates on the influence of interwire/interlayer contact phenomena as regards strand overall axial, torsional and free bending characteristics. For the present purposes, simple methods are proposed for predicting various spiral characteristics, covering: wire kinematics and strand lateral contraction under axial load; axial stiffness and hysteresis; and free bending stiffness and hysteresis of axially preloaded strands. Results are presented for strands up to 184 mm diameter and for a wide range of wire diameters and lay angles. (A)