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Welding Rebar

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It hasn't been 20 degrees below zero around here since the last time Hell 
froze over, but a number of years ago, our city fathers thought that it would 
be nice to have a jet fighter mounted on a pedestal in one of our larger 
parks, which was located on a main thoroughfare.  The pedestal was to be one 
of those slender, soaring pedestals that are frequently seen on desks holding 
models of planes.  Getting a jet fighter wasn't a problem either as 
Davis-Monthan Air Base is a storage facility for aircraft taken out of 
service.  The reinforcing (A 615, Grade 60) was specified to be welded 
together.

Everything proceeded well; the plane was trucked from storage; a crane 
hoisted the plane on top of the pedestal and was securely bolted to it.  The 
crane slacked off; the plane nose-dived into the ground.  The plane was taken 
back to the storage/dismantling facility, the pedestal was removed, nobody 
talks about it any more!

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Ed Fasula wrote:

>>I understand that AWS allows welding A615 rebar with low hydrogen rods, and 
it seems to be an accepted procedure. However, I have seen A706 rebar noted 
for use where weldability is important. I can't see when weldability wouldn't 
be important when used in a welded application, unless it were a 
non-structural
connection.  (In our area of rural construction, specifying A706 would
probably be a first.)  

Chief Industries shows tie-rod welding details for A615 Gr. 40 with E70XX low
hydrogen rods.  Does it matter that it's grade 40?  I don't find a reference
telling if A615 is a carbon, high-carbon, or low-allow steel.  I would think
Gr. 60 would be sort of a higher carbon mild steel, but I have no idea how
it's made stronger than Gr. 40.  What if it's welded on a 20 below zero day
like we have in MN (well, rare this year), couldn't it get brittle?

Thanks for any information and/or advice.<<