Rebar in a suspended slab #60 vs. #40 3

[skibum2b]

Hello out there - I have an interesting question based on reality.
Suppose a home was built, with a suspended concrete slab. The architect/engineer specified #60 rebar on 12" centers, two layers offset 6" (not technically correct, but you get the picture).
Suppose the guy pouring the slab used #40 rebar (40ksi).
What are the possible failures, etc?

It is the garage floor of a home.

Thanks.

 

[JAE]

I said "unless it goes plastic"

which I guess it does

 

[hokie66]

It makes a big difference in the effort to bend bars. In Australia, our standard grade is 500 MPa, but they make 250 MPa bars for the swimming pool builders, who bend 12 mm bars onsite.

 

[BAretired]

It does if you want to bend it through an angle theta. The work done is Mp*theta where Mp is the plastic moment of the bar.

BA

 

[BAretired]

hokie,

Many of the housebuilders around here prefer small diameter bars (10M usually) so that they can bend the bars on site. I have no problem with that, but the fact remains that the effort required to bend a bar is directly proportional to the yield strength of the material.

BA

 

[skibum2b]

No - rebar is already totally enclosed in the concrete.

 

[BAretired]

skibum2b,

No - rebar is already totally enclosed in the concrete.

No to what? I don't understand your comment. Please elucidate.

BA

 

[hokie66]

BA,
He was answering dik's query 21/10/09, 1408.

 

[apsix]

"The concrete guy replied that he used #40 instead of #60 'cause the #40 was easier to bend."

Did he also use 6" of concrete instead of 8" because it was easier to pay for?

As already said, contact the original designer. The only way to determine the effect is to have specific knowledge of this particular slab.
If you want generic advice it would be; slab strength is inadequate unless shown otherwise.