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Ce 479 Fall 06

Steel Floor Deck

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Types of Floor Deck on Steel Joists/Girders

• Cast in Place Concrete on Steel Deck• Basics- Page 19 of Vulcraft Catalog• Non-Composite- Pages 20-31 (Also referred to a

conform decks)– SDI Specs and Commentary- Pages 32-39

• Composite- Pages 42-49– SDI Specs and Commentary- Pages 50-59

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Non-Composite Steel Floor Decks• A form deck (conform) must safely support self weight, the weight of

the wet concrete, and construction activity (rarely shored).

• Steel form deck for floors is manufactured from sheet metal and available in three finishes: painted, galvanized and unfinished (black). Form deck which is permanent (painted and galvanized) carries its own weight, the weight of the concrete during construction (wet) and after it has hardened.

• Some manufacturers consider the painted deck not a permanent form. Unfinished (black) deck is not considered as a permanent form. In both of these instances, the concrete slab must be designed to carry its own weight.

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Non-Composite Form Decks

• 1.5 VLI

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Design Criteria for Steel Deck

• Design: SDI Specs and Commentary-Pages 32-36– Material Properties

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Design Criteria for Steel Deck

• Allowable stress and deflection criteria

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Catalog Tables• This table lists the maximum construction clear spans

based on the SDI criteria

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Design Criteria for Concrete Slab

• LRFD 318-05

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Reinforced Concrete Slab Allowable Loads Table

• It shows the load carrying capacity of the concrete slab reinforced with welded wire fabric

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Design Procedure

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Slab Reinforcement

• The slabs are reinforced with welded wire mesh. It must be noted that the reinforcement shown not always meets temperature and shrinkage requirements in the ACI code. However, based on past experience of performance this deviation is allowed

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Example Non-Composite Design

Determine the capacity of a 4.3” normal weight concrete slab on a 1.3C steel deck. The clab is reinforced with 4x4- W2.9xW2.9 grade 60 WWF, f’c = 3000 psi. The WWF is to be undraped. The steel deck is continuous over 3 equal 4 foot (clear) spans.

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Check• From Table “Maximum Construction Clear Spans (SDI

Criteria)” with L = 4 ft, note that all gages would meet criteria for a 4.3” slab. Use 1.3 C26 to use minimum weight (45 psf).

• Table “Reinforced Concrete Slab Allowable Loads” for 1.3C26 with L = 4 ft, for a three span condition with D = 4.3” using W4x4- 2.9x2.9 gives an allowable superimposed uniform load of 322 psf (not in bold, undraped mesh). Assuming a painted or galvanized steel deck, the slab does not have to be designed to carry its own weight.

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Draped Mesh Condition

• Take same 1.3C deck with W4x4- 2.9x2.9 mesh, with a D = 4.3” slab (t = 3”) on a three-span condition, L = 7’ – 0”. Assuming painted or galvanized deck, the table superimposed allowable load on page 24 of the Vulcraft catalog is 158 psf. Note that it appears in bold type. Note 5 indicates that it will require that the mesh be draped. Check it! Also, notes that a 1.3C20 deck is needed to satisfy the construction SDI criteria.

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d and beff for M-

• Section is symmetric• d = ?• b = ?

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Reinforced Concrete Slab Allowable Loads Table

• It shows the load carrying capacity of the concrete slab reinforced with welded wire fabric