On Thu, 23 May 2002, "Ford Peterson" wrote
> My county's wind speed is 80
> MPH. I've been here 6 years now and I've seen that in gusts at least
twice.
> In the first event....
For anyone analyzing their own designs, the sobering point of Ford's and
others TowerTalkians' experiences should be to underscore that gusts of
80 MPH and higher are absolutely to be expected in an 80 MPH wind zone.
The 80 MPH designation in the spec refers to an average, sustained wind
speed; in this case its an average speed of 80 MPH averaged over 45
seconds. The instantaneous wind speed in a gust can be signifcantly
higher than the wind zone designation.
Even then there's a 1 in 10 chance that the 80 MPH average itself is
exceeded within a 5 year period.
Having a design which includes a resaonable margin of safety is very
prudent when dealing with stochastic loading like wind.
73,
Mike K1MK
Michael Keane K1MK
k1mk@alum.mit.edu
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