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Joints in concrete floor slab on bar joists

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....  The contractor, without notifying anyone, substituted 0.6" x 28 ga
slabform. =
 No reinforcement was provided.  No joints were provided in the floor.
As I started looking into the problem, I realized that I could not find
=
a specific reference recommending  the use or nonuse of joints in such a
=
floor system.  I would appreciate some help on this.
=20
Since there is essentially no theoretical floor strength, it appears =
that the entire floor may have to be removed and replaced with =
reinforcing.  There are occupied offices directly under this floor.
=20
Any comments?
=20
Thanks,
Dave Smith


I have three:

1.  28 gauge?  They wrap baked potatoes in stuff like that, don't they?

2.  This will end up costing the Contractor a lot of money.  Industrial
darwinism at work.

3.  Load tests.  Lots of load tests.  I believe the standard is proof
testing to at least 125 percent of the required strength.  Configure the
test apparatus to conservatively mimic the racking feet or whatever else
is intended to be used.

Frankly, I don't think much of trying to calculate capacities of thin
unreinforced slabs, especially in a situation such as yours where it
sounds like the concrete may not be that great, and it's already all
cracked up.  We don't know as much as we think we do about stuff like
that.

Oh, in answer to your first question, we don't joint floors on
structure.  As was pointed out, the underlying structure pretty much
renders them useless.  But we have composite deck and some mesh in the
floors.  In your case, I doubt joints would have accomplished anything
except to provide neat shear lines.

HTH,
Mike Hemstad, P.E.
TKDA
St. Paul, Minnesota

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