Let me just state that you and every other tower owner has a legal
responsiblity not to overload their tower beyound the code minimum. In the
event that a tower falls due to neglience by the designer, installer or the
owner, they can be held civilly and criminally responsible for property
damages, injuries and deaths resulting from the tower falling.
ROHN towers are designed using a computer program to meet the requirements of
ANSI/TIA/EIA-222-F and the factors of safety incorporated therein. This means
that the antenna loads stated in the catalogs are the maximum for the stated
wind speed that can be used for the given arragement and still meet the
requirements of EIA-222. The EIA also contains the minimum wind speed for
each county and some locality have increased these wind speeds.
As far at the "break away" antennas go, the EIA-222 states the following:
2.3.2 The horizontal force (F) applied to each section of the structure
shall be calculated from the equation:
F = qz GH [CF AE + Sum (CA AA}] (lb) (N)
Not to exceed 2 qz GH AG
when AG = Gross area of one tower face (ft2) [sq m]
(Note: All appurtenances, including antennas, mounts and lines, shall
be assumed to remain intact and attached to the structure regardless of
their wind load capacities.)
Quite honestly you have me at a disadvantage in this formum because I cannot
reveal my identity for professional reasons. So let me end with:
Overloading towers is a bad idea and if you do, let your next tower be a ROHN.
tower2sell@aol.com
In a message dated 10/8/1999 10:09:58 AM Central Daylight Time,
K4LM@worldnet.att.net writes:
> I really didn't want to get into this but let's get real. If you took a
> survey
> of what is really out there you would see a lot of tower systems overloaded
> according to Rohn. And as for the "wire" effect, it won't have the whole
> antenna
> attached. Booms break, elements break and masts bend.
>
> Everyone has to assess their own situation. I am in a 110 mph zone and I
> have PE
> certification for 14.8 sq.ft. of antenna on Rohn 25G, guyed at 30 - 60 -
90
> ft
> with 1/4" EHS. However, I will never see 110 mph winds until a strong
> hurricane
> hits West Palm Beach directly. The highest winds we see are 50 - 60 mph
> bursts
> during rain storms. Do I spend 1000's of dollars to plan for a wind storm
> that
> hits every 25 years, or do I put up what I know will survive 99.9% of the
> winds I
> have now. As someone else said, you have insurance to pay for the other
.1%
> of
> the time. Those of you that live in 70 mph zones also get tornados more
> often
> than I get hurricanes. Do you or can you design for a tornado. I don't
> think
> so.
>
> I know many big name DXers and Contesters with antenna systems that would
> make
> Rohn have nightmares. For example, I helped a well known DXer in Atlanta
> put a 3
> element Telrex 40 meter beam at the top of 130' of 25G. I won't go into
a
> long
> list, but I have put up and taken down 100's of towers in the past 30
years
> and
> 25G is strong stuff. Just don't go more than 30 ft. between guy points
and
> only
> use Rohn hardware.
>
> Rohn has to meet building codes, but they also have to worry about
liability
> of
> their product. Their numbers are VERY conservative.
>
> Before you guys start flaming me, take a look at what is out there and ask
> how
> well it survives the wind. And please don't waist time telling me about
> all the
> towers that meet the specs. They are there too and if I had the money I
> would
> only put up 55G.
>
> Furthermore, how many of you put up used tower against Rohn advice??
--
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