ACI 318-19 Min. Shear Steel for one way slabs

[Sam123456LA]

Hi All,

Apologies if this thread has already been started. I searched around the forum but could not find a similar link.

Under Clause 7.6.3.1, ACI-318-19 indicates that Av,min is required for all regions where Vu>phi*Vc. It then says in the commentary that "the basis for minimum shear reinforcement for one way slabs is the same as that for beams".

It then refers you R9.6.3. for additional information.

The question I have is; When does one have to apply minimum shear steel for one way slabs? Is it the same equation for beams i.e. when Vu>phi*f'c^0.5*b*d?

I find the commentary confusing as in one sentence it indicates that solid slabs and footings have less stringent shear requirements but then it goes onto say that deep, lightly reinforced one-way slabs may fail at shears less than Vc.

Thanks in advance.

 

[rapt]

When Vu > phi * Vc for one way slabs
when Vu > .5 phi * Vc for beams.

 

[ProgrammingPE]

Slabs do have less stringent minimum shear requirements than beams. Beams require minimum shear reinforcing when Vu > 0.5*ΦVc and slabs require it when Vu > ΦVc. (See Section 9.6.3.1 for beam minimum shear reinforcing.)

I see where your confusion is coming from, though. Back in ACI 318-11, the minimum shear reinforcement for beams and slabs were addressed in the same section (11.4.6). The commentary was a little clearer then since it was more obvious what the differences were between the beam and slab minimum shear reinforcement.

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