Steel Deck Load Distribution

[CloudSan1]

Steel deck/metal deck are used for one way slab because of the direction of its corrugation. When used in a one-way slab, say for example a 6m x 2m slab, the steel deck corrugation shall be placed parallel to the shorter direction and it will produce a one-way slab load distribution right?

But what if the steel deck/metal deck must be placed on a 6m x 4m slab? Will it still produce a one-way load distribution even if the dimension of the slab is considered as a two-way slab? Or will it have a two-way load distribution?

If it's the latter, is there a way to have the steel deck distribute its load in a one-way direction on a 6m x 4m slab? Thanks.

 

[BAretired]

There could be some two way action, but the slab is thinner in the direction normal to the flutes of the deck. Normal practice is to consider it a one way slab. Usually, deformed deck is used, which provides additional steel reinforcement at the bottom of the slab.

BA

 

[milkshakelake]

If it's a composite deck, the concrete will bond strongly to the direction of the flutes and it will be much stiffer than the weak direction due to composite action, so it would definitely be a one way slab. If it's a thin form deck (form decks can be considered sacrificial though they still have some stiffness contribution) and there is a large concrete topping and there is bottom rebar in both directions, it could be considered a two way slab. You can calculate the load contribution in each direction similarly to a two way slab (either by hand or with an FEM model), with different stiffness in each direction. But you'd really have to design it that way on purpose to get that two way load distribution.

It does depend on what kind of deck and reinforcement you're using. For small concrete topping, the moment of inertia in the strong direction would be much greater than the weak direction.