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> Today's Topics:
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> 1. More on Rebar Cages (Gary E. Jones, Ph.D.)
> 2. Re: Re-Bar Cage Advise (K4SAV)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 22 Jan 2006 07:53:03 -0600
> From: "Gary E. Jones, Ph.D." <garyejones@cmaaccess.com>
> Subject: [TowerTalk] More on Rebar Cages
> To: <towertalk@contesting.com>
> Message-ID: <018d01c61f5b$2f6019b0$0302a8c0@dell4400>
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> I want to thank the many replies to my question about fabricating the
> rebar cage for this HDX-589 MDPL crank up. I have had many good
> suggestions. This particular cage specs call for pairs of #13 rebar (1
> 5/8" each ) for each of the four outer legs, each 8' long. The
> horizontal braces call for #4 rebar bent in a square shape (3' 6" in a
> side) and each of those goes around the outside of the vertical pairs of
> big rebar. To do this to spec, you can't build it in sides or pieces and
> put it together. And the pairs of #13 rebar are damn heavy (8 of them
> total) so the wire ties have a lot of work to hold the cage together in
> any position other than vertical (where the weight is on the ground and
> the big "legs" are standing upright)
>
> It appears that the four side big rebar pairs have to be held in place
> horizontally to build it, and the small rebar fitted over the big legs
> vertically (assemble it on its side), and then tilt it into place with
> the excavator or whatever digs the hole. I have had a suggestion to
> build a jig out of plywood to hold the sides together during assembly
> and then cut it off after the fact, and that might work. I might also
> try to figure out some way I could suspend two of the side rebar pairs
> horizontally ~4 feet off the ground so I can assemble it all as it hangs
> from these sides, and then tilt it vertically to go in the hole. .
>
> Several suggested building it in the hole. A complication is that these
> towers are going into packed sand on a mountaintop (a million years ago
> the geologists tell me that it was a river-bed before the land had an
> upheaval). Although it will hold the base just fine because it is very
> hard packed, I have been advised not to get into the hole for any reason
> due to the heightened possibility of a wall collapse. So, building it in
> the hole will not work.
>
> I have an arc welder so I could spot-weld critical pieces to help hold
> it in place. Does anyone know what distinguishes "weldable" re-bar from
> "non-weldable" rebar, and what the result of welding re-bar that is not
> "weldable".. ( I assume it weakens the rebar below spec.)
>
> This is one of those projects that, looking back over it all, I think
> that this is one that I should have paid a specialty fabrication shop to
> fabricate for me and let them do the work !! I may yet decide that
> discretion is the better part of valor, and take these pieces to the
> pros to see if they can put it together for me reasonably.
>
>
> Thanks all for the help.
>
> Gary W5FI
Gary
We used to do this all the time on the job.
Two ladders lashed into a A frame and a simple rope pulley.
Roughly wire tie the four corner rebars to the side rebars.
Using the rope pulley lift the now wobbly set upright
start at bottom to wire tie the bottom horizontal side rebars.
keep moving up the cage
lower the assembly into the hole as you need.
No heavy lifting.
HINT: We always ran the lowering rope through the ladder rungs so that the
vectored force
was in line with the ladders and gave a easy tie off.
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