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Title: Predictions of static and dynamic performance of multi-layered spiral strands under various loading conditions.
Author: Huang, Yu Ping.
Awarding Body: South Bank University
Current Institution: London South Bank University
Date of Award: 1993
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The upper bound to the frictional damping of axially preloaded single layer strands subjected to cyclic bending to a constant radius of curvature has been determined. The theoretical model includes a modified frictional approach which takes no-slip to full-slip friction transition over the individual interwire contact patches into account. Numerical results show that cable damping may be increased by increasing the number of wires and/or increasing the lay angle. Using the orthotropic sheet concept, and employing established results regarding the frictional contact of non-spherical bodies, an analytical model has been proposed for estimating the bending stiffness and hysteresis of axially preloaded multi-layered spiral strands undergoing uniform cyclic bending movements. Also investigated are the bending characteristics of axially preloaded sheathed spiral strands experiencing high external hydrostatic pressures such as those in deep water platfonn applications. Based on a series of theoretical parametric studies on a number of realistic multi-layered sheathed spiral strands, a series of straightforward formulations aimed at practicing engineers were developed. Numerical results are presented for a number of realistic spiral strands with diameters as large as 184 mm, covering the full range of practical wire diameters and lay angles, and experiencing a wide range of mean axial loads and imposed radii of curvature. A theoretical model for determining WIre stresses III helical strands undergoing bending to a constant radius of curvature has also been proposed. The individual wire bending stresses are shown to be composed of two components -i.e. those due to presence of interlayer friction and those due to wires bending about their own neutral axes. The final theoretical results show that the maximum wire axial stress components due to interlayer friction are much greater than the corresponding single wire bending stresses. Based on theoretical studies on bending hysteresis of axially preloaded multi-layered spiral strands and previously reported experimental observations, the structural damping factor in axially pre loaded spiral strands undergoing lateral vibrations under, say, vortex shedding conditions can now be predicted. Closed-form solutions for predicting the extensional-torsional wave speeds and displacements in axially pre loaded spiral strands experiencing specific forms of impact loading at one end with the other end fixed, have been developed. Finally, a theoretical model for estimating the recovery length of a fractured wire in parallel wire strands prestressed by external wrapping or clamping have been developed. In this model, the transition from the full-slip to no-slip interwire friction, as one moves away from the fractured end, is taken fully into account.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Structural engineering Structural engineering Civil engineering