[TowerTalk] Adjustments to Tower Base Pier J-Bolts
jim.thom at telus.net
Sat Jul 22 11:18:23 EDT 2017
Date: Sat, 22 Jul 2017 09:47:49 -0400
From: "Paul Christensen" <w9ac at arrl.net>
To: <TOWERTALK at contesting.com>
Subject: [TowerTalk] Adjustments to Tower Base Pier J-Bolts
<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.
## How many 1.875 J bolts are on each corner ? What is the template made from ?
Is it like a steel cue rack ? Since the holes in the template are 1.875 and the holes in the
tower base section are exactly 2.0 inch.... why not just cut the template, perhaps in the center
of each face of the template. Then the template should come off easily. You may have just
enough wiggle room to get the tower base section onto the J bolts..on all 3 x corners.
## With 12 inchs of those massive 1.875 inch rods above the concrete, and I assume that most or
all of the 12 inches is threaded.... 2 x templates should have been used, stacked above each other,
with a space between them. Then the 6 ft long J bolts would not have shifted at all, they would not
have budged. Moot point now... but of significance to others, including Pirod.
## A 1.875 threaded rod, sticking 12 inches above the concrete, imo, is not about to budge.
I would not apply heat, you may well ruin or degrade the yield strength of the bolts.... and or
damage the galvanizing..since I think zinc melts at c 850 F. Then you could end up with zinc
into the troughs of the threads.... and then have a helluva time getting the giant nuts on. Im guessing
the nuts are aprx 3.0 inch....flat to flat ?
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