Folks:
Been there, done that, on a Rohn 25, 50 footer free standing, of a ham
friend, donating some tower work....The tower was professionally installed,
with what looked like a 5' by 5' square concrete base. I did not know how
deep the concrete was. I assumed the engineering was right because the
tower was installed by a well known local 2 way radio business...
I worked on it from time to time, on my friend's TA 33 beam, and was
DEFINITELY uncomfortable with the sway and 'exposure' I felt 50 ft up,
unguyed. Kept telling myself quietly...Well this WAS installed by a 2 way
contractor.. must be right.....I later was told that there was no official
Rohn specs for any unguyed 25 tower, but that it was not uncommon to have
done on a case by case basis (with case by case engineering) to heights of
40 ft. Gave me the Willies......haven't been up that tower since.
73, DX, de Pat Barthelow AA6EG aa6eg@hotmail.com
>From: "A.J. Farmer (AJ3U)" <farmer.aj@gmail.com>
>To: Steve Shelton <Steve@bnjcomp.com>
>CC: towertalk@contesting.com
>Subject: Re: [TowerTalk] tower specs/not wind loads
>Date: Tue, 24 Jan 2006 16:00:04 -0500
>On 1/23/06, Steve Shelton <Steve@bnjcomp.com> wrote:
> > Hi, I am fairly new to towers and I have tried to research information
> > on rohn's 25, 45 and 55 towers. I have found quite a bit of information
> > on these towers but not the exact answers that I am looking. One of my
> > questions is what is the maximum safe height on these three towers
> > without guying? How much weight can they handle guyed or unguyed? The
> > reason I ask is that I do a lot of tower climbing and often run into a
> > rohn 25 that is not guyed. Most are only 40' but some as high as 80'
> > and without guy wires these towers do a lot of swaying. I would feel
> > more comfortable on these particular towers if I knew for sure that an
> > extra 200lbs harnessed to the side of this tower is not going to be the
> > stick that broke that camels back. Thank you for any information that
> > you have.
>
>C'mon fellas - none of you answered this guy's question but instead
>hijacked the thread and started on about other things not even related
>to his question...
>
>Steve, my understanding is that the maximum freestanding height of
>Rohn 25G is 30 to 40 feet. I would assume that this limit allows for
>an average (200lb?) climber doing maintenance, but I have always
>wondered the same thing. I don't know about 45G and 55G, but I do
>know that they were designed as guyed towers, not freestanding.
>Everyone talks about wind load, but what about the load of somebody is
>hanging off the side near the top? How does that compare? I don't
>have the engineering experience to do this calculation. Perhaps
>someone on this list knows how to do this? If so, then that load can
>be compared "apples to apples" with a wind load, right? Some hard
>numbers sure would make me feel better about being up there... I have
>a 30 foot freestanding 25G tower and it makes me nervous when it sways
>when I'm on top. I can't imagine being up 80 feet unguyed... You are
>a brave man, indeed!
>
>--
>A.J. Farmer, AJ3U
>http://www.aj3u.com
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|