One thing I do NOT see often in these collapse discussions, is
discussion of the merits of self supporting towers in these tight
situations.
A guyed tower is made of the same stuff at 0-10 feet as it is at the
top. The guys keep it up. If the top wants to come over, suddenly
missing a guy or two, there is hardly any stiffness to keep it in the
vertical.
A self-supporting tower is made of much stronger stuff at the bottom
than at the top, and apparently has a VERY different failure mode. I
have heard only one failure story on a Trylon self-supporter. (LXC,
any tales or stats on self-supporting?)
That was 50 mph winds after 2 inches radial ice. It twisted the top 30
feet which bent over on itself. So far as I know, the bottom half of
the tower was reused after the bent stuff was removed.
If the nature of the ordinance or setback rules or size of lots are
going to keep one down below 100 feet anyway, why not get some mileage
out of self-supporting towers in the local rules? So many feet setback
for guyed towers, some significant amount less for self-supporting.
And with self-supporters you can do things like run a safety wire to
the top to latch onto when climbing. (There are many advantages to no
guy wires, other than causing that skinny Rohn 25 to fall.)
And there is a new company (besides Trylon and the very expensive Rohn
self-supporting) doing self-supporting towers that looks quite
interesting.
73, y'all.
Guy
----- Original Message -----
From: <KD4OL@aol.com>
To: <Towertalk@contesting.com>
Cc: <rfb@geocities.com>; <nc4jd@summit.net>; <crow@summit.net>;
<JefferyLDavis@aol.com>; <malgray@fls.infi.net>; <w4ima@erols.com>
Sent: Tuesday, April 09, 2002 4:12 AM
Subject: [Towertalk] Inquiry - Tower Collapse/Fall/Radius Zone
> Good Morning,
>
> This is a follow-up to my previous posting several days ago.
>
> We are working with our local municipal, public officials regarding
Tower
> Ordinances. We appreciate the thoughts and advice to our previous
inquiry.
>
> However, this time we would like to be even more specific in our
request. We
> are trying to identify and obtain copies of any studies that
identify what is
> a typical Collapse Zone, Fall Zone, Fall Radius of a tower subject
to
> collapse or failure.
>
> Our municipality has informally suggested a tower height setback
from
> property lines that may be considered excessive. We are trying to
provide
> information to them that would elevate their Safety concerns.
>
> We feel that we might be able to accomplish this through competent
research
> into this area. Empirical results would be very helpful to us.
>
> Can anyone help?
>
> Thank you,
> Hank Smith, KD4OL
> Virginia
>
>
> --- StripMime Report -- processed MIME parts ---
> multipart/alternative
> text/plain (text body -- kept)
> text/html
> ---
> _______________________________________________
> Towertalk mailing list
> Towertalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
|