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Re: [TowerTalk] US Tower MA 550 Windloading - 90MPH?

To: <>
Subject: Re: [TowerTalk] US Tower MA 550 Windloading - 90MPH?
From: "W7CE" <>
Date: Tue, 12 Sep 2006 07:53:02 -0700
List-post: <>
>>  The City is  asking to see wind loading calculations for 90 MPH as well 
>> as
> calculations  for radial ice.  I am trying to convince them that I will 
> have
> it
> nested most of the time (which I will).  The info I got from US Tower  has 
> a
> lot
> of detail but it only goes up to 70 mph.  Has anyone run  these 
> calculations
> on
> this tower for 90 mph both fully extended and  nested?
> For neighborhood aesthetics, I really want to stay with the tubular  look.
>    I think someone has already mentioned that it  won't make that 
> windspeed
> fully extended. The last one I got a PE stamp for (I  think it was a
> 72-footer) was for 85 MPH and it was rated for a 25 pound load.  The 
> rating goes to
> zero and below at higher windspeeds.
>    You better get the lattice one or go with a  non-crank-up 
> self-supporter
> or a guyed tower to get what you need.

Washington State has adopted the International Building Code (IBC) and it 
appears that many other states are doing likewise.  I looked at the 
windspeed charts that accompany the new code and, if I'm reading it 
correctly, the minimum design speed is 85 MPH no matter where you live and 
obviously higher is some locations.  Here in Lacey (near Olympia), they've 
adopted 90 MPH.

Tower manufactures like US Tower seem to be behind the times.  I've talked 
to them several times and their 130' crankup, which isn't even in the 
catalog, is the only tower they would spec at 80MPH.  This towers lists for 
over $40K and they still won't give adequate IBC specs.  For their 106' and 
89' models, the highest windspeed that they would spec is 70 MPH.  I don't 
mind paying for engineering, but I would like to go into it knowing that the 
manufacturer already believes that the tower is adequate.  Those of us who 
live in IBC states need to start pressing the tower manufacturers for specs 
that comply with current laws.  I'd like to put up a 100'+ free-standing 
tower that can handle 30 sq ft at 90 MPH, and have just about decided to 
give up on the ham-oriented manufacturers and start talking to the 
commercial manufacturers.  At least they understand windspeeds over 70 MPH.

Clay  W7CE


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