Concrete on Steel Deck 1

[NewbieStruct]

We are looking to change the loading on an existing building. The existing building has a 3.5" thick floor deck (0.6C conform deck and rest is concrete). There is no reinforcing in concrete. According to the deck catalog with welded wire reinforcing, the capacity is 400 psf. However, there is a separate table that shows capacity with deflections. In that table, the loads are lower than the reinforced slab loads. We are able to achieve the new capacity according to that. My guess, the welded wire fabric is for temperature and shrinkage in this case? What it be okay to add the additional loading?

 

[slickdeals]

Not only for temperature and shrinkage but also to provide capacity for negative moment in the concrete over the support beams.

 

[wannabeSE]

I would not use the reinforced concrete table for unreinforced concrete. Vulcraft's Conform deck is a non-composite form deck. The Vulcraft catalog says:

"This table shows the load carrying capacity the concrete
slab will develop when it is reinforced with welded wire
fabric (mesh). For the loads shown in light print, the live
loads were calculated with the mesh halfway between the
top of the slab and the top of the deck. This is considered
'undraped'. The loads shown in bold print were calculated
using the mesh near the top of the slab as negative
reinforcement at the supports and near the bottom of the
slab as positive reinforcement between supports. This is
called 'draped'."

Also, more information is available in the Steel Deck Institute Standard for Non-Composite Steel Floor Deck that can be downloaded at

http://www.sdi.org/sdiansi.htm.

 

[NewbieStruct]

The deck capacity that we require works with the undraped condition. However, there is no WWF in the concrete. Is the slab good for the new capacity without the WWF?

 

[JAE]

0.6C deck is a Vulcraft product that is a non-composite deck system - a form deck.

The deck itself does not serve as reinforcement for the deck-slab system like composite decks do.

The concrete-deck tables Vulcraft provides uses the WWF as traditional reinforcement for the slab capacities - both for positive and negative bending moments.

The table across the page is the deck-only capacity table and would typically have no bearing on your design with a reinforced concrete slab on top of it.

However, if your slab truly has NO reinforcement (WWF or otherwise) the non-concrete load tables are what you would use.

If your slab has WWF in it, and it is positioned properly in the slab, then the non-concrete load tables are not applicable and you can use the reinforced concrete tables
that Vulcraft provides based on the size of WWF in the slab.

 

[NewbieStruct]

Thanks, JAE.

That clears my doubt. I can use the deck only capacity. The concrete and other dead load plus live load is just the super imposed total load on the deck.

 

[dik]

Is the concrete floor (deck and conc) 3-1/2" thick? or 5" thick (assuming the deck is 1-1/2"? What is the span? I don't have a Vulcraft catalogue.

Dik

 

[NewbieStruct]

The total thickness is 3.5". The span is 2'-6".