concrete roof on metal deck shear

[civil_4343]

I need to calc shear on a 4" concrete roof slab on 1.5" metal deck. The reinforcement is #4 @ 8" O.C. both ways. The metal decking is non-composite.

In ACI 318-19 Table 22.5.5.1 for Vc, what is my bw and d. The reinforcement is not called out to a depth, so I was using d = 2"? What do I use for bw for (a) Vc = 2λ[(f'c^1/2)+nu/6Ag]bwd ?

 

[KootK]

There are a few different ways to look at this depending on your particular situation.

Here's an excellent reference to start with that deals with some of this: NEHRP Deck Diaphragm Design Guide. This is the source for the clip below.

You may ultimately also benefit from getting your hands on SDI's Deck Diaphragm Design Manual. As you likely know, a critical design aspect is often how you get the shear into, and out of, the deck.