[TowerTalk] tower specs/not wind loads

[Pat Barthelow]

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 at hotmail.com

>From: "A.J. Farmer (AJ3U)" <farmer.aj at gmail.com>
>To: Steve Shelton <Steve at bnjcomp.com>
>CC: towertalk at 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 at 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