That's horrifying. I think I would have released the guys on one side and
pulled it over, rather than risk the climb. Even with everything tight, didn't
the rust give you pause?
K7NV's Yagistress web site has an interesting discussion of pier pin versus
embedded section bases, including finite element analysis of the effects of a
pier pin base on distribution of stress in a guyed tower. In correspondence,
Kurt commented, IIRC, that the basic Rohn "pier pin" base probably behaves
somewhere between a real pier pin and a fixed base, because it uses a large,
flat plate with a hole in it through which a small diameter pier pin protrudes.
The result is significant friction between the base and the concrete below,
which of course increases when wind forces put additional downward force on the
tower.
My Rohn pier pin base on 97 feet of R25 shows essentially no signs of having
moved at all in the 11 years the tower has been up.
73, Pete N4ZR (not an engineer)
At 10:05 AM 4/17/2006, Terry Gerdes wrote:
>All,
>
>This weekend I took down a 150 foot of R25 tower with elevated guy posts. All
>three elevated guy post were leaning. The northern guy post was leaning very
>bad and in addition there were a couple of lower support braces that had been
>added to stiffen it up. The tower was lightly loaded with a DB224 on top.
>
>I have never seen a tower with so slack of guys. Considerable effort was done
>just to get the guys tensioned up so the tower could be taken down. The tower
>was constructed on a pier pin and it obviously moved around a lot in the wind.
>
>Pic of leaning elevated guy post: http://www.ab5k.net/images/R25ElGuyPost.jpg
>
>Pic of slack guys: http://www.ab5k.net/images/R25SlackGuys.jpg
>
>
>73 Terry - AB5K
>
>
>
>
>
>
>
>
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