Design of One way Slab | Design of RCC Slab |



Step No. 01: Sizes

Step No. 01: Sizes

h = l/24 × (0.4+fy/100000) = 4″ (Minimum by ACI for end span

y h = l/28 × (0.4+fy/100000) = 3″ (Minimum by ACI for interior span)

End span governs. Finally take assumed h = 6″

Effective depth (d) = hf – 0.75 – (3/8)/2 = 5″ (for #3 main bar)

 Step No. 02: Loads

Step No. 03: Analysis

Bending moment diagram for slab

Step No. 04: Design
Calculate moment capacity provided by minimum reinforcement in slab:

Asmin = 0.002bhf = 0.002 × 12 × 6 = 0.144 in2/ft

ΦMn = ΦAsminfy (d-a/2) = 0.9 × 0.144 × 40 × (5-0.188/2) = 25.4 in-k/ft



Φ Mn calculated from Asmin is > all moments calculated in Step No 3.

Therefore As = Asmin = 0.144 in2/ft (#3 @ 9.166″ c/c)

This will work for both positive and negative steel as Asmin governs.

Main reinforcement spacing:

Maximum spacing for main steel reinforcement in one way slab according to ACI 7.6.5 is minimum of:

3hf = 3 × 6 =18″

18″ z Finally use, #3 @ 9″ c/c.




Shrinkage steel or temperature steel (Ast):

Ast = 0.002bhf Ast = 0.002 × 12 × 6 =0.144 in2/ft

Shrinkage reinforcement is same as main reinforcement, because:

Ast = Asmin = 0.144 in2

Maximum spacing for temperature steel reinforcement in one way slab according to ACI 7.12.2.2 is minimum of:

5hf =5 × 6 =30″ OR 18″ z Therefore 9″ spacing is O.K.

Step No. 05: Drafting

Main reinforcement = #3 @ 9″ c/c (positive & negative)

Shrinkage reinforcement = #3 @ 9″ c/c

Supporting bars = #3 @ 18″ c/c

 

Designed by: Dr. Qaisar ali

Engr Sami Ullah Author

Founder & Admin of civilstudents.com I am Civil Engineer working as a Site Engineer. With a good subject knowledge in civil Engineering. And I have started the blog to share my valuable information with civil engineer students. Civil Global is the Civil Engineering learning Home around all over the world.

Comments

    sentayehu begashaw

    (January 22, 2018 - 3:13 pm)

    Tnx, its gd information .

    A Ramamoorthy

    (March 11, 2018 - 6:52 am)

    How to top Crank length calculate with example & L/4

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