[TowerTalk] wind load
noddy1211 at sbcglobal.net
Thu Feb 18 20:29:25 PST 2010
WIND LOADING: Engineering analysis indicates the tower will support 23
square feet of projected area at 85 MPH 3 second gust wind speed per
ANSI/TIA EIA RS
222 Rev. G.
Does not matter what you think or feel, all that matters to the local city
these days is the example above.
Hi Rex et al
Yeah, but for how long?
I've always wondered if that is a sustained 70 mph wind for 5 hours or a
gust or 2 at that speed. 73
I believe it's saying that at 70MPH, the tower will support 15 sqft of
antenna/mast/whatever is put on it. Most antennas will specify effective
"wind load" in square feet of "projected area."
I've been looking at various tower specifications, and often see
something like this
Maximum Wind Load
70 MPH 15 sq. ft.
I don't really understand how to interpret this. I think a wind load
is a (static) force, and therefore should be measured in either
newtons or pounds. IIUC, it should be proportional to the square of
the wind speed and that the constant of proportionality should itself
be proportional to the cross-sectional area to the wind. So 15 sq ft
is an area, and 70 MPH is a wind speed, but I'm still missing some
factors in order to calculate a force.
Can anyone shed some light?
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