I use four 10 foot 4.5 inch OD 1/4 inch wall steel pipe for a 62 foot Rohn
25 Fold Over tower with a 2 element quad. The vertical anchors are buried
in the ground 5 1/2 feet with a 16 inch diameter hole 65 inches deep filled
with cement. The end of the pipe is drilled and bolted to two 32 foot # 6
copper ground wires that are buried for ground radials for each guy-wire
anchor. I had the design analyzed in San Diego county when I had to get a
permit (even for a rural area on 6 acres). The soil is San Diego County is
Decomposed Granite, where your soil condition is probably different. An I
beam is a nice solution as there is a nice wide flange to directly bolt the
turnbuckles, where on the pipe, welding is necessary to get a suitable flat
surface.
I would not use anything buried only 3 feet deep and sticking out of the
ground 7 feet for a 60 foot tower with reasonable amateur radio antennas.
The overturning moments are very high for a vertical guy anchor. You can do
a lot better letting the guy anchor be in line with the guy wires and using
a large concrete piece at the bottom of the hole. The normal design
criteria is for the concrete to weigh as much as the guy wire tension under
full rated wind loads, which assumes that the ground is totally saturated
and the weight of the anchor cement base is the primary resisting force.
This is inexpensive, listed is most Rohn catalog details, and can use much
smaller metal guy anchors since the only force is tension.
Since the anchors will be in your neighbors yard (which I wouldn't do in a
million years), you should pay a Professional Engineer to analyze (and
probably run a soils test) and stamp the calculations for the guy anchors.
This should ensure that you have a safe solution and it will not yield a 3
foot depth that could give you serious problems.
You might look carefully at the four point guying system that Rohn used to
use on their Fold Over Towers. For a 62 foot Rohn 45 tower, it used 8 guy
wires and the whole thing fits in approximately a 25 foot radius, which fits
most small city lots and keeps all the anchors on your property.
Subject: [TowerTalk] I-beams used as guy-wire anchors!
I have been on this reflector for several months.
Aside from the occasional sidetrack, it is pretty darn knowledgeable.
Having said that...I was wondering if anyone has had experience with using
I-beams to anchor their guy-wires? I have a Rohn 25 G up 60 feet. It has
the two, called for guy positions, one at 28 feet and the other at 55 feet.
Would a 10 foot , W-6 X12 X10 foot handle the load? I would cement it in
the ground 3 or 4 feet. The company says that this I - beam would weigh 120
pounds. Twelve pounds per 1 foot of I-beam. I have never dealt with this
before as I usually run my guy-wires to the ground. This is an unusual
situation because I have been graciously permitted by a neighbor to place
two on his property. An attempt at using 10 foot schedule 80 galvanized
water pipe got me no where, I now seek help using the I-beams so I can get
6 or 7 feet above ground to allow grass mowing. I'd appreciate your
considerations.
Regards
73
Conrad
WB3DQD
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