ACI 318-14. Minimum reinforcement in cantilever walls

[darkjmf1]

Hi all,

ACI 318-14, cl.11.7.2.3, says:
"For walls with h greater than 10 in., except basement walls and cantilever retaining walls, distributed reinforcement for each direction shall be placed in two layers parallel with wall faces in accordance with (a) and (b):
(a) One layer consisting of at least one-half and not exceeding two-thirds of total reinforcement required for each direction shall be placed at least 2 in., but not exceeding h/3, from the exterior surface.
(b) The other layer consisting of the balance of required reinforcement in that direction, shall be placed at least 3/4 in., but not greater than h/3, from the interior surface."

Does it mean that in a cantilever retaining wall, all minimum reinforcement defined in "Table 11.6.1 Minimum reinforcement for walls with in-plane Vu ≤ 0.5ϕVc" cannot be divided between both faces and has to be deployed entirely in each face?
E.g., if minimum horizontal reinforcement required is 0.0020, we are not allowed to use 0.0010 on each face, but have to use 0.0020 on each instead. Seems a lot to me. Why such big amount in this type of walls?

Thank you in advance.

 

[rapt]

If the reinforcement is required for strength, as it is on the tension face of a cantilever retaining wall, the full minimum is required on the face requiring the strength.

Splitting between faces is only allowed in the secondary unloaded direction for shrinkage and temperature and really only then if it is unrestrained and not too long.

 

[darkjmf1]

Thanks for your quick answer, rapt!

According to that, wouldn't be necessary any minimum reinforcement at all in the compression face?
But in the case of a basement wall (with slab at top) where both faces at tensioned (inside face at middle height and soil side at the base of the wall), we are supposed to deploy the complete minimum reinforcement at each face, aren't we?

You also speak about the "secondary unloaded direction" -which makes total sense to me- but why ACI clause refers all the time to "each direction" without distinction of main or secondary directions?