Special Corner Reinforcement

[SuperTall]

Hi all,

I need help understanding something in ACI 318-08 R11.1.3.1. I have a suspended slab hanging on all four sides from structural walls. It looks exactly like Figure R11.1.3.1(e). The last paragraph of R11.1.3.1 indicates that for this hanging condition, "Shear within the connection should also be investigated and special corner reinforcement should be provided."

So my question is, what does "special corner reinforcement" mean here? Does it mean to make sure the wall's vertical bars extend into the slab and are properly anchored (hooked) to the slab's horizontal reinforcing? Does it mean to provide vertical or horizontal shear reinforcement in the connection's space?

To greatly simplify construction, I am detailing the slab to be poured first, and the supporting walls to be poured on top of the slab. My slab also requires shear reinforcing (it's a heavily loaded industrial slab, and we can't go any thicker). I am planning on extending the slab's shear reinforcing through the portion of the slab below the wall connection (I know I have congestion issues to worry about here).

I appreciate any input on this. If possible, please also provide an explanation and any supporting references to your interpretation on this.

Thanks much!

 

[asixth]

Personally I hate hanging conditions with rc slabs. I have always provided an embedded plate with threaded reinforcement and nuts to anchor the slab and mechanical splices in the hanging element. For the shear, I think that would be that you don't get any compression zone at the face of the support because it hangs and it doesn't bear.

 

[BAretired]

Special corner reinforcement might refer to the fact that you will develop "corner-levers" in all corners which tend to push up in the corner and down away from the corner. Additional reinforcement is also required in the slab in the corner regions to prevent cracking due to corner-levers.

BA