Re-entrant Corner Reinforcing - Code Reference

[FoglesongEng]

I am aware from experience to always add diagonal reinforcing in a re-entrant corner in a slab on grade. I normally require (2)-#5 x 4', with 1" clear from the top of the slab.

However, I am now in the position where I have a slab with a textbook 45 degree crack from multiple re-entrant corners within 20 (+/-) days of placement. The situation is though that as an owner's representative, I need to provide proof to the owner that these bars were "required by code." I have looked in ACI 315 (Detailing of Reinforcing), ACI 224.3R (control of Cracking), ACI 224.1R (Causes, evaluation, and repair of cracks) and none of these "require" diagonal reinforcing at re-entrant corners. ACI 360R (Design of Slabs on Ground) has Figure A7.3.3 which shows the diagonal bars, but it is considered "typical conceptual details that have been used sucessfully on projects."

Has anyone ever seen a reference that states these bars are "required?" Thanks in advance.

 

[JAE]

I don't think it is a code requirement as this is not a public safety issue. I think it is essentially only a serviceability issue in regards to crack control.

 

[dik]

No code requirement that I'm aware of... are the multiple re-entrant corners restrained. What is the sawcut spacing, concrete slump, and time of sawcutting?

Dik

 

[jike]

No code requirement that I am aware of, but it is good practice to include in construction documents.

 

[hokie66]

Agree that there is no code requirement. You can't depend on a code for everything, and you need to educate the owner in that regard.

 

[rowingengineer]

If you were in Australia; AS2870; there is a requirement for re-entrant corner reinforcing.

http://www.nceng.com.au/

"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning."

 

[Huong83]

Entrance corner often a place of high local concentration load. Shrinkage cracks can pass through there.
If you use a finite element program to model a slab, you often see that a very high local negative moment at the entrance corners.
Usually 2 bars of 12mm diameter is enough. Sometimes, I put more if very high local moment happen there.

 

[Ron]

Standard of Care

 

[kylesito]

No US code that I know of. It's a serviceability crack control detail.

PE, SE
Eastern United States

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