On Sun, 12 Dec 2004 18:27:33 -0700, Mark & Juanita
wrote:

|On 11 Dec 2004 21:20:47 -0800, wrote:
|
|... snip
|Background:
|A friend of mine is working for the Army who is doing a construction
|project for the Border Patrol in southern California. This project
|mainly involves building box culverts, runoff slabs and road beds.
|According to my buddy, these structures are built to interstate highway
|specifications, even though a 5/4 ton pickup is the heaviest vehicle
|these roads will probably ever see.

They ought to be building a 50' high wall from San Ysidro to
Brownsville.
|
|
|... our tax dollars at work.
|
|The Plot Thickens:
|A Chief Warrant Officer (a surveyor by trade) told this crew, who was
|putting in a steel rebar mat, that only every third joint be tied
|together. This raised some discussion among members of the crew, one
|of which swore that OSHA required that every joint be tied. This, to
|me, sounds like a dumb-ass thing to say. ANSI maybe, but not OSHA.
|Further, he swore that the joints could not be welded, as the welding
|process weakens the steel.

The Navy ought to know.
|
| That particular statement alone should have been enough for the crew to
|have told the CWO to go pound sand. The strength of weld joints is
|actually stronger the the steel itself.

Oh, please.

The discussion concerns REBAR, not steel plate. ANSI/AWS D1.4 is one
applicable standard. It is quite expensive to buy.

I am not a welder, structural engineer or metallurgist, however, I've
worked with all three and know that welding rebar is not a trivial
exercise.

One reference I have at hand, "Placing Reinforcing Bars", Concrete
Reinforcing Steel Institute, Chicago IL, 1970, states in part," The
field welding of crossing bars should be avoided.... Tests have shown
that this can reduce the strength of a bar to 35 to 40 percent of its
capacity."

For example, one of my metallurgist co-workers investigated the
results of some missile warhead testing against steel-reinforced
concrete bunker targets.

The Navy built the bunkers to be used for warhead proof of
performance. When the destruction exceeded the calculated results, it
was determined that instead of tying the rebar in a one-foot grid; the
Navy had welded the joints.

My friend showed me a one foot length of #10 rebar that looked like
the ends had been cut on a shear. The whole target area was covered
in one-foot long pieces of rebar and the sand that you wanted that CWO
to pound.

You tax dollars funded a retest at about $1M per missile.

Thank you very much.

Here's a quick reference from a PE:

http://www.k1ttt.net/technote/welding.html