Wire Recovery Length in Suspension Bridge Cable

Abstract

A differential equation capable of describing the full-slip to no-slip friction transition along a fractured wire in a parallel-wire strand experiencing external hydrostatic pressure, by prestressed wrapping or intermittent cable bands, has been developed. The model is based on a modified version of a previously reported theoretical work in conjunction with well-established results in the field of contact-stress theory. With some reasonable simplifying assumptions, closed-form solutions to the differential equation have been obtained that provide simple means of estimating the wire-recovery (or development) length. Recovery length is defined as the length measured from the fractured end of the wire, in which the wire will be able to carry its appropriate share of the axial load. The theory has been developed for an idealized cable, and possible practical limitations of the model have been critically addressed. The present findings should prove useful as a first step toward the development of appropriate discard criteria for parallel wire cables used in, for example, suspension bridges.