If anyone wants to be serious about this, the formula for the pull-out
resistance of lag screws is on page 8-10 of this document
<http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_08.pdf>.
Compare whatever numbers you get to the ultimate strength of 3/16 EHS
guy wire, factor in an appropriate safety factor, and I bet you'll
abandon the idea. We have an old sugar maple that has 7 cables holding
its canopy together, and the cable anchors use long through bolts, big
nuts, and bigger washers on the back side of each. I certainly would
not climb anything guyed that way that has been subjected to severe stress.
73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
On 3/12/2014 4:45 PM, Steve Oksala wrote:
I have a problem, and hopefully the experts on this forum will be able to
help.
My tower is 50 feet of Rohn 25, with a Force 12 C-3 on top. The tower has
been up for around 30 years. It has been guyed at 25 and 45 feet with
standard steel cable. The guys were anchored as follows: Guys A were into a
pine tree at about six feet; some years ago the tree died, and the stump was
left to hold the anchors. Guys B were also into a pine tree at about six
feet, and like Guy A the tree died and the stump was left with the anchors.
Guys C were about six feet into a large maple tree.
At the end of fall, I disconnect the lower guys as I planned to replace
them. However time was limited, and the tower was guyed only at the 45 foot
level. Earlier this winter, we in the Philly area had a severe ice storm.
The result was that - I think - that the ice load on the guys was very high.
The result was that the screw-in for Guy A pulled completely out of the
stump; the stump which contained Guy B pulled completely out of the ground,
with the screw-in still attached; and Guy C was still connected. However the
tower now has a distinct tilt. Just recently I was able to examine it, and
the cement base in which the tower was set has actually tipped somewhat, so
one side is about an inch up above the ground and the other side is a little
bit below. The base is tilted toward the maple tree where Guy C remained
intact, and I can only assume that the weight of the ice on the guy wire
pulled it into this new position. (The antenna held up fine.)
The question I have now is what to do next. I do need to climb the tower to
replace the rotor cable (unrelated issue) and install an inverted V around
40 feet. But I don't know if I should simple reguy it as is, or fix it - and
if I fix it, what does that mean? Do I need to dig up all around the base,
straighten it out (by pulling on the top guy wire, which is still attached
to the tower), and then filling in around it with new concrete? Demolish
all that concrete and replace (a huge job, I would think)? What other
options exist? I should also note that when I put it up I did not use any
rebar, just the hole and concrete I mixed and poured.
Any advice would be appreciated. If there is a consensus that this should be
left to an expert (I am 70 years old and used my brain for a living; no
construction skills)? If so, any recommendations?
Thanks in advance for your expertise.
Steve Oksala
NI3P
Ni3p@comcast.net
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