The recent discussions about whether wire "rope" is suitable for guying
towers seem to me to have mostly missed the primary issue, which I
believe is this:
In many guyed tower configurations, a major component of stress on
certain tower sections during periods of high winds is a *bending*
stress (in contrast to, say, a purely compressive force). This bending
stress originates in the *elongation* of the guy wires under increased
tension from the wind loading on the tower and antennas. Flexibility of
the guying material is of little import here -- only its tendency to
stretch under the applied loads. If you are trying to obtain maximum
utilization of a guyed tower (i.e., "more stacked beams!!!"), relative
elongation for a given length and a given wind loading is the
specification you should be concerned with.
K7NV has some good modeling studies on his web site; it's been a while
since I've gone through them, and as I recall his thrust was primarily
to analyze the relative impact on tower loading from low beams versus
high beams, but the message is clear -- low stretch guy wires allow you
to do much more with a given tower.
Bud, W2RU
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