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[TowerTalk] Re-bar Cage - welding ??

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Subject: [TowerTalk] Re-bar Cage - welding ??
From: "Jim Thomson" <jim.thom@telus.net>
Date: Thu, 23 Sep 2010 07:36:02 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Date: Wed, 22 Sep 2010 17:01:50 -0400
From: Roger <roger@rogerhalstead.com>
Subject: Re: [TowerTalk] Re-bar Cage - welding ??


If you look at the construction of most rebar cages it appears the cage 
does little. It's the individual sections of rebar, their shape, and 
overlap. IOW the cage is there to keep the concrete from losing 
structural integrity.

## Concrete has loads of compression strength, but very little tensile strength.
[stretching].  Wood has more tensile strength than concrete, so does plastic. 
The re-bar is to improve the tensile strength.  Pour some concrete, and 
form it into a 12" square, x 5/8"  thick.  Wait a month, then smack it with a 
hammer,
and watch it explode.  The stuff has no strength.  If they didn't put re-bar in 
floors
in high rise buildings/condo's, the floors would collapse under their own 
weight.

##  Line  a tower base with concrete on all 4 x sides,  +  the top,  and it's
now one homogenous  block of cement.   


I've welded quite a bit of rebar, but it was in uses where strength was 
not paramount. "so far" I've never run into a problem with the welding, 
but as has been stated the content of all but given specifications is 
uncontrolled. It could be easy to come up with some alloys that would 
end up with crystalline welds containing very little strength.

##  if u used 60 ksi weldable re-bar, you won't have a problem.  The stuff
is relatively cheap. 

Jim  VE7RF 



73

Roger (K8RI)
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