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Guy Anchors on a flat concrete roof

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Subject: Guy Anchors on a flat concrete roof
From: (John Brosnahan)
Date: Tue, 27 Aug 1996 06:42:12 -0600
At 08:30 PM 8/26/96 -0700, you wrote:
>Since guy wires seems to be the topic today let me put this situation 
>in front of the forum.
>If you have been following my notes you know I'm going to put my tower
>on top of our office roof which is concrete.  Luckily my tower and guy
>points all fall on top of the main support structures.  I wonder if the
>architect was a ham?
>Anyways, I found a local supplier of Ramset concrete fastners that will
>hold the base plate and guy anchors.
>Heres my question.  Rohn specifies that the normal guy anchor should
>be in line with the guy wires.  My problems is that I can only drill 
>straight down into the concrete.  
>        / <----- guy wire 
>       / 
>     O/ <------------ guy anchor (probably a forged eyebolt)
>_____|_______ Roof
>     |
>     | <-------- Eyebolt surrounded by epoxy made for the job 
>As you can see, the guy wire is going to want to bend the guy anchor.
>But I can't see anyway around it.  The dealer did not suggest drilling
>the hole at a 45 degree angle.
>I am estimating that the eye bolt will only extend a few inches above
>the roof so as to leave just enough room to install an equalizer plate.
>Does anybody have any suggestions or do you think this will work fine?
>(p.s.  need to get this done before the October contest season, HI)

Couple of possibilities come to mind.

1)  There are two kinds of forged eye bolts.  The plain kind and 
the kind with a forged ring around the bottom of the eye--which are
designed to have a load not in line with the bolt section.  This second
kind is the only one to use in this application and I would error on
the very heavy side if at all possible.  This forged ring foundation
around the base of the eye MUST be in contact with a solid surface.

2)  But the way I would do it is to use a Ramset rod that provides
a threaded stud sticking out of the concrete.  I would then
take a piece of steel bar stock and drill a hole in each end--one end
for the Threaded Stud coming out of the concrete and the other end
to accomodate a clevis that the equalizer plate attaches to.  I would
put a bend in the bar stock at the threaded rod end that allows it to bend
up to a line that is appoximately midway between the direction of the
various guy wires.  The length of this bar stock rod should be long 
enough so that the equalizer plate is a convenient height above 
the roof.  I would galvanize the bar stock if possible or use a few
coats of the cold spray galvanizing.  The bar stock should be right
at the point where the threaded stud sticks out of the concrete roof.

BTW It doesn't cost much extra to use a much larger stud than specified
for some extra peace of mind.



John Brosnahan  W0UN
24115 WCR 40
La Salle, CO 80645

"Radio Contesting IS a Contact Sport"

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