Abstract
The wind-induced vibration of cables is the
source of numerous fatigue failures in strands
of electric transmission - line cables. At
present, the emphasis in the field is directed
at reducing or eliminating the amount of vibration
by adding dampers and vibration
absorbers rather than at reducing the induced
stress in the cable by rational design of the
suspension system. This paper reports the
experimental measurement of actual strains
in a vibrating cable.
An experimental test span was constructed
to observe the actual conditions of stress
under wind-induced vibration and the conditions
for the onset of vibration, and to evaluate
the suspension clamp effects. Actual
strains were measured at a number of points
along the cable at intervals over a three"'
lOnth period. The maximum strains due to
.... eolian vibration were observed in the flow
Reynolds number range from 2000 to 5000 for
winds normal to the line. Above this range
there appears to be a definite deterioration of
the vortex street causing the vibration of the
cable.
Through the experimental information that
has been gathered, it will be possible to reduce
the magnitude of stress induced by the
suspension clamp through improved clamp design. It would also be possible to take advantage
of such reduction by increasing cable
tension. This would permit longer spans and
shorter transmission towers, reducing the
over-all cost of transmission lines.
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