[TowerTalk] Tower base "challenge"

[Dan Cisson]

"GETTING SERIOUS",, A LAG SCREW IN A DEAD,DECAYING  STUMP IS USELESS....
----- Original Message ----- 
From: "Pete Smith N4ZR" <n4zr at contesting.com>
To: <towertalk at contesting.com>
Sent: Friday, March 14, 2014 4:32 PM
Subject: Re: [TowerTalk] Tower base "challenge"


> 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 at comcast.net
>>
>>
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>>
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