[TowerTalk] Tower base dimensions - why?

[Bill Austin]

Alan makes a good point.  The first thing you should do is find out 
what's required, and then explore your options.  It doesn't matter much 
what you calculate or think is best, it's what the engineer who designs 
the foundation comes up with that really matters.

I live in the same area as Alan, but in a different jurisdiction.  His 
building department required a design that met calculations for 90mph, 
mine required 150mph.  His foundation was a little smaller (like 
4x4x7deep) and used something like 4 yards of concrete, where mine was 
10x10x5deep and required 13 yards of 4500psi concrete.  His tower is a 
40ft Heights, mine is a 60ft Trylon.

Things are going to be a little different for every tower.  It's very 
important to follow the design engineers plan, along with your building 
department's requirements.

73,
Bill



> One thing to consider is what your Bldg Dept requires before they will 
> issue a Bldg Permit. In my case they required 90 MPH Wind Calcs to 
> IBC-2000 specs. I was going to order a tower from U.S. Towers but all 
> they could provide were 70 MPH wind calcs to UBC-97 specs. These were 
> not acceptable to my Bldg Dept. U.S. Towers does not have a full time 
> PE on staff to do the wind calcs and told me they could get them from 
> an outside P.E. for $250.00. I gave them the OK to contact the outside 
> P.E. but he was not able to provide them.
> Guess what I'm trying to say is rather than seeing what all the 
> options are find out first what will be accepted.
> 73 & GL
>
> Jim Miller wrote:
>
>Your answer is exactly why I think the deeper base would be the most stable.
>Guess I didn't specify why in the original message.  Waiting to see what the
>engineers have to say.  Good luck with Ivan.  Looks like you will get real
>wet if nothing else.
>
>
>     73, Jim
>
>     ----- Original Message ----- From: <Cqtestk4xs at aol.com>
>     To: <TOWERTALK at contesting.com>
>     Sent: Thursday, September 09, 2004 9:04 PM
>     Subject: Re: [TowerTalk] Tower base dimensions - why?
>
>
>
>         One more thing to consider.....the push on the tower from the
>         wind trying 
>
>
>     to
>
>         overturn the tower, trying to put it on its side. The higher
>         the tower 
>
>
>     the
>
>         more leverage on the base from the wind. The bigger and deeper
>         the tower 
>
>
>     the
>
>         more resistance to the overturning momentum from the wind.
>         This, of 
>
>
>     course,
>
>is probably not very important if the tower is guyed, since the Rohn
>catalogue only specifies a four foot hole for Rohn 55 at 200 feet.
>
>
>         I'm not an engineer, so the above is in layman's terms. I'll
>         let you know 
>
>
>     if
>
>         a big base is important next week if Ivan hits the West coast
>         of FL.
>
>Bill K4XS
>_______________________________________________
>      
>
>
> --
> __________________________________________________________________________ 
>
>
>Alan Zack
>Amateur Radio Station K7ACZ
>Las Vegas, Nevada, USA
>Quality Engineer, The Boeing Company, Retired
>Aviation Chief Warrant Officer, U.S. Coast Guard, Retired
>U.S. Coast Guard, Always Ready, Always There
>Every hour, Every day, Around the Clock and Around the World
>SEMPER PARATUS
>http://gocoastguard.com
>
>
>
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>
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