RESPONSE OF AXIALLY PRELOADED SPIRAL STRANDS TO IMPACT LOADING

Coupled extensional-torsional behaviour of axially preloaded multi-layered spiral strands under specific forms of impact loading is considered. By employing coupled extensional-torsional constitutive equations for steel cables, a pair of wave equations, describing extensional-torsional displacements at any location along the spiral strand with one end fixed against movement, are obtained. Due to the presence of significant levels of interwire friction, it is argued that for sufficiently small levels of externally applied impact loads on axially preloaded and fully bedded-in spiral strands, one must use the no-slip (i.e. rigid rod) version of the constitutive relations in preference to the traditional full-slip versions which are the ones often quoted by cable manufacturers based on their shop measurements. Comparison of numerical results for the wave propagation data based on the no-slip and full-slip constitutive relations suggest substantial differences which may have significant practical implications for non-destructive wire fracture detection devices which are currently under development.