[TowerTalk] Adjustments to Tower Base Pier J-Bolts
K7LXC at aol.com
K7LXC at aol.com
Sat Jul 22 11:49:10 EDT 2017
> Got a nasty situation here that needs some brain power to resolve.
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
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
bolts, thinking the template would keep them perfectly straight.
> Each 6 ft. bolt is exactly 1-7/8" in diameter. Each protrudes 12"
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
minimize shift of the type that occurred anyway. The tower base section
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
tower base will absolutely go on without trouble.
> Some options:
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
heating will do to the strength of the J-bolt.
2) Use a telescoping hydraulic cylinder (a.k.a. hydraulic ram jack) to
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
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
Heating the bolts should be okay. I don't think it'll appreciably
cause a problem - but I'm not an engineer, just a tower builder. Use a 6' or so
piece of pipe as a lever to help move them.
The other thing you could do would be to enlarge the leg holes to
accommodate the slight off-set. That'd be what I'd do.
Cheers & GL,
TOWER TECH -
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