[TowerTalk] Adjustments to Tower Base Pier J-Bolts
john at kk9a.com
john at kk9a.com
Sat Jul 22 11:48:10 EDT 2017
Instead of compromising the bolt or concrete, can you elongate the tower
holes? You may also be able to shorten the bolts to minimize the portion
that is out of location.
To: <TOWERTALK at contesting.com>
Subject: [TowerTalk] Adjustments to Tower Base Pier J-Bolts
From: "Paul Christensen" <w9ac at arrl.net>
Date: Sat, 22 Jul 2017 09:47:49 -0400
Got a nasty situation here that needs some brain power to resolve. Earlier
this year, I poured two base piers for a pair of Pirod self-supporting
towers. The 140 ft. tower base has the problem. Unfortunately, the base
J-bolts on two of the three equilateral triangle points are bent inward,
toward the base center by 1/8". That 1/8" may not seem like much, but it
is. In fact, the template used during the pour cannot be removed. During
the pour, the J-bolts were double-nutted, one on top and the other below the
template. Still, the force of the concrete pour managed to push out the 6
ft. J-bolts. As that was settling, I quickly moved the crew to the other
tower as sunset was minutes away. I did not go back and take a level to the
bolts, thinking the template would keep them perfectly straight.
Each 6 ft. bolt is exactly 1-7/8" in diameter. Each protrudes 12" above the
concrete surface. Moving these huge bolts even 1/8" will take a Herculean
effort. The template holes are the exact same diameter and made that way to
minimize shift of the type that occurred anyway. The tower base section has
mounting holes that are exactly 2.0" in diameter. So, there's just a small
amount of wiggle room. If we can get the template off, then I know that the
tower base will absolutely go on without trouble.
1) Use an oxy-acetylene torch and apply heat at the point where the J-bolts
exit the base, then pound with a sledge hammer. Trying it now without heat
is futile; we've tried and the bolts are going nowhere. I have no idea what
heating will do to the strength of the J-bolt.
2) Use a telescoping hydraulic cylinder (a.k.a. hydraulic ram jack) to push
the two J-bolts against each other since they are both leaning in by the
same amount. What I don't know is how much adjusting precision I'll have
when expanding the cylinder. Do these things move in very small increments?
What cannot occur is the cylinder "jerking" the bolts to anything beyond
1/8". These cylinders are capable of pushing 30,000 lbs. and are typically
used on large earth-moving front loaders.
I'm open to any other ideas.
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