Analysis of Multilayered Structural Strands

End fixity to spiral strands undergoing cyclic bending

“…The magnitude of at least the initial ðEIÞ eff of the spiral strand, on the other hand, is a function primarily of the longitudinal wire stresses around the extreme fibre position, where the onset of variations (reductions) in the interlayer shear stiffness associated with reductions in the imposed radii of curvature is expected to lag considerably behind those around the neutral axis. It must be emphasized that, in view of the helical nature of the individual wires, in axially preloaded spiral strands the radial contact forces are a minimum at the interface between the outer and second (penultimate) layers and tend to increase substantially inwards, towards the core (King) wire where radial pressures become a maximum [14]. It, then, follows that interlayer slippage initially starts between the outer and penultimate layers and gradually moves inwards, towards the centre of the strand, with the proviso that it is certainly not impossible for the innermost layers to experience some form of interlayer slippage in the vicinity of the so-called neutral axis prior to the occurrence of interlayer slippage between the two outermost layers around the so-called extreme fibre position [6].…”

Simple determination of the axial stiffness for largediameter independent wire rope core or fibre core wire ropes

“…The results from the orthotropic sheet concept were subsequently used by Raoof and Kraincanic [9,13] to develop two somewhat different theoretical models for analysing the various stiffness characteristics of wire ropes with either a ®bre or an independent wire rope core. As originally shown by Raoof and Hobbs [12], in repeated (cyclic) loading regimes, due to the presence of interwire friction, the effective axial stiffness of axially preloaded spiral strands (with their ends ®xed against rotation) varies (as a function of the externally applied axial load perturbations/mean axial load) between two limits. The axial stiffnesses for small axial load changes (cf.…”

“…Raoof and Hobbs [12] have developed the orthotropic sheet theoretical model: this concept is capable of Fig. 1 A typical six-stranded wire rope with: (a) an independent wire rope core (IWRC) (after Lee [8]) and (b) a ®bre core (after Velinsky [5]) predicting, with a good degree of accuracy, the mechanical characteristics of spiral strands under not just static monotonic loading (which, incidentally, is the type of loading the previously reported frictionless theoretical models have primarily been developed for) but also when the strands experience cyclic loading.…”

Helical Birods: An Elastic Model of Helically Wound Double-Stranded Rods

“…With this assumption equations (14)- (16) would need to altered, but equations (17)- (20), in conjunction with (4) and (6), can still be used to define the curvatures u ij of the individual rods. Additionally equations (31) and (32), (33) and (34) would still apply, so we can completely define the kinematic description of the rods in terms of the contact line R, the angles β i and α i , and the function ∆ s . However, the description could be heavily dependent on the potential deformation of the rod.…”

“…By individual elements we mean the smallest scale of structure for which there is no further macroscopic cross-sectional structure (i.e., in Figure 1(a) there are two such continua composing the rope structure, in Figure 1(b) there would be many more). This as opposed to treating the composite whole as a continuum [14,19,34], an approach that can greatly simplify the modelling but which would omit vital aspects of a rope's mechanical response. In particular, the finite volume of individual elements of the rope leads to geometric constraints relating the fact that individual elements will often be in contact with each other, and it must be ensured that they cannot overlap when deformed.…”