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Old 12-12-2007, 06:12 PM
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Default Rebar for concrete pillars - weld or tie..

so i get an order for 25 concrete pillars poured inside 2' dia. Sona Tubes...

the guy wants the rebar cages inside the tubes to be welded...

is that OK or do they need to be tied w/ wire

I've seen it both ways but not sure what to tell him...
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Old 12-12-2007, 06:33 PM
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The code where I live is tied,......... Had a buddy doing his own foundation last summer, tack weld the rebar in the forms, and failed inspection. The building inspector wouldn't let him reuse any of it because it had welded spots, so he had to replace ALL the rebar, and redo the job.

Why,...... I don't know
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Old 12-12-2007, 07:19 PM
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Quote:
so he had to replace ALL the rebar, and redo the job.

Why,...... I don't know
Because he could while acting within his power and the fact that he's most probably a prick as well.
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Old 12-12-2007, 07:31 PM
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Generally speaking almost all rebar is tied. Most rebar does not weld well (the chemistry limits on rebar allow for lots of stuff that "normal" steel doesn't allow). I believe there is a grade of weldable rebar but it is fairly expensive and not that common. Almost all of the concrete work I've seen done (including some massie bridge piers) all use tied bar. It's faster and probably cheaper

That being said, check your local building code, and go from there.
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Old 12-12-2007, 07:57 PM
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NOW the next stupid question. Was the guy notified of proper procedure when the permits were pulled.In town where business is located you pull permits and if not regular trade you receive a sheet with expectations.i.e electrical ,wire size , conduit size ,clearance requirements .Same setup on carpenter and concrete .Structural steel they want the engineer plans and stamp.Though they will allow site built trusses .
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Old 12-12-2007, 08:11 PM
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I have got several rebar cages to quote on within the last year. All were for the City of Chicago, all the prints had the rebar welded with 7018 rod and tied with 316 stainless wire (11ga IIRC)...

I believe it is whatever they want, and depending on which union pays off the Bldg Dept and the inspectors the most... :evil:
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Old 12-12-2007, 08:18 PM
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I looked thru the Inter. Building Codes 2003 and didn't see a spec. on tied or welded on first look thru
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Old 12-12-2007, 08:33 PM
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Quote:
Originally Posted by Tanstaafl View Post
Generally speaking almost all rebar is tied. Most rebar does not weld well (the chemistry limits on rebar allow for lots of stuff that "normal" steel doesn't allow). I believe there is a grade of weldable rebar but it is fairly expensive and not that common. Almost all of the concrete work I've seen done (including some massie bridge piers) all use tied bar. It's faster and probably cheaper

That being said, check your local building code, and go from there.
I've seen the illegals (guest workers, excuse me) on big road projects tie the steel and then overlap two pieces by 2 feet or so and then weld those together..

I haven't talked to the guy about permits yet, we're at the back of the envelope stage
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Old 12-12-2007, 09:13 PM
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i have taken a re-bar welding test for welding precast beams in the field
1 1/4 inch rebar laid flat on 3/8 plate....one pass down each side...5/32 7018 must have 3/8 fillet...no undercut and then if you pass that..they cut the re-bar in half and your two welds can be no more than 1/2 inch apart..the rebar was just pulled from the rack outside before the test..so if needs to be special or not to weld i don't really know but i do know a lot of this stuff does get welded
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Old 12-12-2007, 09:24 PM
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Matt Shade wrote in another thread here on SFT
--------------------------------------------------------------------------------

Quote:
Rebar welds up just fine with whatever you've got handy. I've welded it with 6011 or 6013 rod, and ER70 wire. Its easy to find free and comes in handy for all sorts of stuff.

When you hear that you aren't supposed to weld rebar for structural projects, they're talking about welding rebar that is meant to be used for concrete reinforcement. Concrete structures are designed specifically to meet certain load criteria and the amount and placement of steel reinforcement is determined by a lot of math. One of the main rules followed is that structures are to be designed so that the steel reinforcment will yield before the concrete does. This is because steel tends to yield slowly, bending or sagging, while concrete pretty much turns into a pile of dust the instant it gives way.
Rebar comes in specific numbered sizes (which tell how many eighths of an inch its nominal diameter is) and grades, which have to do with its ultimate tensile strength. When you start welding, or flame cutting rebar you basically heat treat it and change its properties. Sometimes it will be stronger and sometimes it will be weaker depending on what you do....but either way the structural engineers get very pissed off when you start throwing random changes into their structure. Pissing off the structural engineers tends to make them hold you liable for stuff and or make you do it over again, so welding rebar instead of tieing is avoided
The same holds true for any structural steel. A36 welds great, but you'd better not get caught welding on a building frame anywhere it isn't called for in the specs.

There are actually marks on rebar denoting what it was melted from. The large majority of it is recycled railroad car axles. This is actually pretty good stuff and makes great cold chisels and punches after being heat treated properly. Thats exactly what they use for the punch and chisel projects in the fabricating classes taught at Ohio State University for their construction management program. They started using it shortly after I took that class, and I got to see some fo the chisels they made. They work really well.
From what I recall from the astm spec (it's been several years since I use the astm spec) Matt Shade is correct. Welding rebar is fine for non structural component. I've welded rebar several times over the years making from making frames for crab traps to making standoffs for guide rails on a home made well drilling rig. -- CEC
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