how to check the number of studs welded to a beam in a composite slab

[struct6]

Hi All,
We want to verify if the contractor has installed the correct number of studs on a beam in a composite slab system. They poured this particular area before we inspected and now the owner want us to make sure that the contractor installed the studs as per our drawings. Anybody has got any ideas to determine the number of studs on the beam beneath the concrete?

 

[msquared48]

Might be able to do this with an electronic rebar finder. As the stud head is probably 1" or so below the top of the slab, the beam would not be detected, metal deck could be if it is ribbed, and any top rebar would be.

You would be looking for a point strike as opposed to a linear one as for rebar. Might have to verify the reading with selective concrete chipping to the head of the studs, and patching.

Other than that, X-ray, or just tell him to remove the slab and pour again, only this time, pour AFTER I inspect. He'll love that.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Einsteim]

2 words - jack & hammer

 

[msquared48]

Point here:

If you don't do what needs to be done, the only A** you'll save will be the contractor's, and you will put yours in his place.

The interests of your client come first after public safety. Don't be Mr. Nice Guy here as you will lose in the long run.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ron]

Mike is right. A magnetic rebar detector will find them. Moving the detector along the expected path, it will peak over every stud. Use a James R-meter, a pachometer, a Hilti PS20 or a Profometer....either of them will work for this.

 

[struct6]

Thanks all for your suggestions. I will use the rebar finder to determine the number of studs. I am pretty sure these guys messed up because they had a dozen studs missing in the bay adjacent to the bay in question. We are determined about making these guys fix it if they screwed up.

 

[steellion]

If it was in your spec to require inspection of steel studs prior to concrete placement, you can probably make them pay for the testing as well.

 

[FinnB]

I have been using a company specialised in impulse radar testing to find rebar in old building that are being refurbished. It's a non destructive test and it can be done quickly without much trouble.

You could probably hire the equipment yourself but I use a company to do the testing as it lessens my responsibility.

You should not be billed for more than a half days working by the testing company for checking a beam or two. In terms of cost it should be less than $1000 to get done.

As others have said the engineer should not have to take responsibility for a contractor going off and doing his own thing. I would write to the client and advise him that the contractor is the person who needs to demonstrate there are studs on the beam. If the contractor is not willing to spend the money to have tests done that show the studs are on the beam then my advice to the client would be that the beam/slab should be demolished and rebuilt. This forces the contractor to deal with the problem.

The link below is to a document that shows some impulse radar images including showing rebar in a slab.

http://www.asnt.org/publications/materialseval/basics/augustbasics/augustbasics.htm