A local metal fab shop a few miles away told me they prefer tack welding rebar
cages because wire-tied cages don't hold shape well in transit. Not sure I buy
into that, particularly if diagonal bracing is used, but that's what they told
me.
The discussion did raise some questions for this novice tower installer. Hoping
to put in a base this spring for a UST TX-472 (4x4x7 cage ...probably weighs
about 250 - 300 lbs).
1. If the cage is constructed near (not in) the hole, what's the best way to
rig it for lowering it in with a backhoe? Seems to me that just tying some lift
straps to the top horizontals at the four corners might pull the cage out of
shape or pull the horizontals off, particularly if wire-tied vs welded.
2. There's another rebar cage fabricator further north that has automated
machinery for cutting and bending. Would it be feasible to have them just cut
and bend the pieces, toss them in my pickup truck and construct the cage
on-site? Reason I ask is I'm not sure if building a cage requires measuring and
cutting as you go to deal with tolerances. I would guess the fabricator's
automated machinery would hold better tolerances on bend radius and bend
location than manual tools in the hands of a novice builder.
3. What's the proper way to electrically bond the tower anchor bolts to the
cage to get a good Ufer ground? The anchor bolts are galvanized.
4. Not really a question, but it's annoying that UST requires a 7 ft deep cage.
From what I understand, rebar stock typically comes in 20 ft lengths. If the
depth was 6 ft 8 inch, you could get 3 vertical pieces out of that 20 ft stock.
Perhaps a practical reason for asking about required rebar lap splice overlap
if you have to extend a length.
Thanks & 73
Shawn - N3AE
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