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Re: monopole antenae retrofit

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I seriously doubt you can increase the height of the tower alone, without
*major* structural modifications.

Assuming uniform wind (and we design for wind increasing with height), the
wind moment would vary with the square of the height.  Simply increasing
the height from 80 to 130 feet would increase the moment at the base by a
factor more than of 2.6.  After all, the reason for increasing the height
is to relocate the transmitters to a higher elevation.  By raising the
"sail" to a higher elevation, this factor would be much larger.

If the original tower base were designed for a stability of 1.5, the
structure would cartwheel across the landscape.

Since neither the tower structure, nor the foundation is adequate for the
increased height, it would seem to be a reasonable requirement from the
municipality to require that the tower be camouflaged.

Regarding "modification" of the tower...  I'm sure the owner isn't
interested in spending any more money than he must.  But, he's simply lying
that the camouflage is the reason it "can't be accomplished".  It "can't be
accomplished", because the laws of physics can't be revoked.

'Sounds like a fun project.

Fountain E. Conner, P.E.
Gulf Breeze, Fl. 32561




----------
> From: JGPE1(--nospam--at)aol.com
> To: seaint(--nospam--at)seaint.org
> Subject: Re: monopole antenae retrofit
> Date: Tuesday, January 11, 2000 9:50 PM
> 
> 
> 
> I have a question about monopoles used for cellular antenna carriers. Has

> anyone ever had to take an existing monoplole structure and camouflage it

> with "branches" to make it look like a tree? Can such a retrofit be 
> accomplished when the existing monopole was originally designed without
these 
> "branches"?  A cell carrier has been asked by a municipality to do this
if 
> they wish to increase the height of the existing monopole from 80 to 130
feet 
> however the cellular company has come back with "Structurally, it cannot
be 
> accomplished". Is it a structural problem or more of an economical one?
Is 
> anyone familiar with these monopole structures and can't they be modified
to 
> support the additional loads? If so, how?
> 
> John G., PE
> Garrison, NY