[TowerTalk] wind load

[Mike]

http://www.mei1inc.com/NAB-2003presentation.pdf

Well, Google comes up with this.  Better make sure that the company that
sells you the tower has the calcs correct for this. My friend across town
put up a US towers 55 foot tower and the calcs were wrong, US Towers would
not do a re-do and it cost him 450 bucks for a independent Structural
Engineer.

My Calcs were wrong for my LM-470, but at least Tashijian put them right for
Gratis.  I would ask your City/County how they want the calcs presented to
them, and then tell the tower manufacture what they have to do.  Usually the
base Tension/Compression calcs are wrong as well, this will defiantly be a
show stopper for a few weeks until it is put right.

For some reason Tashijian shows his calcs to be in Florida, as my City
Engineer said, "this is not bloody Florida".

Mike

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of yetiguy at earthlink.net
Sent: Saturday, February 20, 2010 11:49 AM
To: Tower and HF antenna construction topics.; 'Tower and HF antenna
construction topics.'
Subject: Re: [TowerTalk] wind load


Where can one order a copy of EIA RS-222-G?  The Electronic Industries
Association seems to have evaporated.  Then, I checked the ANSI site eStore
for this spec with no joy. Not even a reference. 

Dennis, K6IFB

-----Original Message-----
>From: Mike <noddy1211 at sbcglobal.net>
>Sent: Feb 18, 2010 11:29 PM
>To: "'Tower and HF antenna construction topics.'"
<towertalk at contesting.com>
>Subject: Re: [TowerTalk] wind load
>
>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.
>
>Mike
>
>-----Original Message-----
>
>
>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
>Tom W7WHY
>
>
>
>
>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."
>
>      -Rex-
>
>     K1HI
>Rex Lint
>  Merrimack, NH
>
>
>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?
>
>73s
>
>
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