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Guy Anchors on a flat concrete roof

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Subject: Guy Anchors on a flat concrete roof
From: (ken smith)
Date: Mon, 26 Aug 1996 22:40:09 -0400
At 08:30 PM 8/26/96 -0700, you wrote:

>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)
First, I'm not a Mechanical engineer, so this is a personal opinion on the
dynamics of what you are proposing. First, I don't think that sticking an
eye bolt up in the air with a bending moment is a good idea. Most of the
concrete anchors give a spec for holding a force strait out, with a sheer
strength for the bolt. But your proposal is like a yagi ten feet up the mast
as opposed to one foot up the mast.

How about looking at making a plate that has the required angle built in to
it for the guy attachment, and having concrete anchors hold the plate tight
to the roof. This would eliminate a bending moment on the bolts.

Ken Smith

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