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Guy Wire Tension

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Subject: Guy Wire Tension
From: (John Brosnahan)
Date: Tue, 17 Dec 1996 21:10:48 -0600
At 05:37 PM 12/17/96 -0800, you wrote:
>Here I am again with more questions and not very good answers.  Asking
>questions seems to be my strong point.
>I don't recall seeing anywhere in an article of authority where it says the
>horizontal components of steep guys must (or should) equal the horizontal
>components of shallow guys on a tower.  So before you go to all the trouble
>to figure out how much more tension you have to put on steep guys than on
>shallow guys to make them horizonally equal, maybe we should determine
>whether or not we really ought to do that . . . huh?


It isn't an ought question--it happens by its very nature!  Take a TV slip up
mast --it is flexible enough to move around until the horizontal components
are in equilibrium.  Same thing applies to a tower--at least until the tower
is pulled off vertical enough so that its own rigidity adds to the equation.

Say you have 30 ft of Rohn 25 sticking up and you put a rope on one
side only.  It only takes a few pounds of pull to deflect it an inch or so--and
if this pull is from the ground then the actual horizontal component is even

For a guyed tower, the tower will move around until the horizontal forces are 
equal-- ie, if the first section is vertical then the (horizontal) guy
forces will be 
equal when the guyed tower is vertical even if the guy angles are not equal and
the guy tensions are not the same.  Physics and mother nature conspire
to make this true.


The rest of the issues you raise are issues that if you don't understand
ALL of the engineering required then you shouldn't be doing anything
other than what Rohn has indicated.  You can certainly use 1/2 inch guy wire
on a Rohn 25 tower if you don't exceed the compressive load on the
legs but the guys will sag a lot when tensioned properly and this sag 
can allow the tower to torque more when torsionally loaded than a properly
installed 1/4 inch guy which will have less sag.  So overcompensating in
one area may create an unsafe situation in another area.

Based on your questions I would suggest that you stick with the Rohn specs.
Not meant as a put down--just meant that until you understand all of the issues
(which you are trying to do with your questions) then you will be safe if
you stay with Rohn and you may not be safe if you don't.

73  John  W0UN

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