Hello Doug,
Is this a commercial project or an amateur radio project?
How much experience do you have installing and climbing towers and antennas
of this magnitude?
Are the 80ft towers new? If so, then the manufacturer must be able to
provide you with PE dry-stamped plans (not neccesarily stamped by a PE in
your state). It would be ideal that the PE study be done under TIA-G. If
the towers were bought used then a tower PE needs to be hired to inspect the
condition of the towers and to do a PE study under TIA-G. It is not safe to
proceed with the project without having stamped structural design
information on the towers. Something like you are describing cannot safetly
be built by the seat of the pants.
If I understand your description then it sounds like the two 80ft towers are
spaced very close and side by side, to brace another rotating mast between
the two guyed towers. Are the 80ft towers actually pre-designed to do this,
or is this an after-market design? Has a PE studied, approved, and stamped
the design?
It is very important to follow ALL manufacturer directions. If they say to
use a crane then use the crane. Never deviate from manufacturer directions.
Finally, the installer and the installation process should be properly
insured. Such insurances are a major investment, but a necessary investment.
A project like you are describing is a very serious structural endevour.
Safety is ALWAYS first!
73, Scott W3TX
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Doug Ronald
Sent: Tuesday, January 17, 2012 6:07 PM
To: TowerTalk@contesting.com
Subject: [TowerTalk] Safety of unguyed tower
Importance: Low
I am in the process of constructing a commercial antenna for HF. The antenna
itself is held in place by two 80' towers side-by-side with the antenna
support going vertically between the two towers. The rotator is at ground
level. These towers are designed to be guyed with four guys at the top of
the 80 foot elevation. Since I am on my own putting this system together, I
need to erect the towers in 20' sections. I have the two bottom 20' sections
in, and I feel safe climbing up the middle of each tower. My reason for
sending this info to this reflector is to try and get a seat-of-the-pants
opinion on the safety of climbing the remainder of the towers as I continue
adding the 20' sections to get the thing up without the guys installed.
The manufacturer has off-the-record said if I must erect it piecemeal, only
put in the lower 20' and then crane the remaining 60' in one operation where
I would attach the guys with the crane still supporting the top sections.
Getting a crane to the remote site where this antenna is located is
problematic which is why I am doing it in sections. They officially sanction
only using a 70 ton crane to erect both 80' towers fully constructed at
ground level up to their final positions.
I am not familiar with any other free-standing towers, so I have no
structural reference to compare mine with; thus my invitation for opinions
on this reflector. I have no structural design information on the towers,
but they are triangular with 26" between the legs - no taper. Each 20'
section weighs about 800 pounds (estimated). They are held in the concrete
base with 1" bolts. Like I said, I'm comfortable with the stability of the
first 20' section, but as I work up to the last section, I'm kind 'a
concerned. Any thoughts? Am I worried about nothing here?
Thanks,
-Doug Ronald
AE6SY
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