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

Todd Coulter N4JRZ at arrl.net
Tue Sep 12 11:07:40 EDT 2006


When I was looking for a tower, I contacted US Tower with the
requirements that I had to meet here in south Florida and they had no
interest in helping me at all. I then contacted Karl Tashjian of
Tashjian Towers (www.TashTowers.com ) and explained to him what I was
looking for and he was the only tower company that would help with the
requirements that I had to go by. Here in Broward county, Florida we
have to have it engineered to the South Florida Building Code which is
140 mph @ 3 second gust. Karl went out of his way to get me what I
needed, and I would recommend talking to him for any tower needs. Good
luck with the tower projects.

                              73's
                              Todd
                              N4JRZ


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of W7CE
Sent: Tuesday, September 12, 2006 10:53 AM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] US Tower MA 550 Windloading - 90MPH?

>>  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.

73,
Clay  W7CE



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