Slab and types of slab

                      "SLAB"

SLAB are classified in two types-
(i) One way slab
(ii) Two way slab
           
          ly = Longer span,
          lx=Shorter span

(i) One way slab:
If
   Longer span/Shorter span > 2

ly/lx  > 2

       ratio greater than 2

(ii) Two way slab

longer span/Shorter span < 2
ly/lx < 2
 ratio less than equal 2.0

In One way slab main reinforcement are provided in shorter direction
Two way slab main reinforcement are provided in both directions

Watch video:-
Difference between one way slab and two way slab

Minimum Area of Reinforcement in Slab

For mild steel (Fy-250, Plain bar):- Not less than 0.15% of the gross area of the
slab.
 (gross cross-section Area of the slab):-.15% bD
          (.15/100)×bD  = 0.0015bD

 For HYSD bar (HYSD-415, HYSD-500) :- 0.12% of the gross cross-section are of
the slab

          =.12% bD =( .12/100)×bD= 0.0012bD

Must watch Segregation in concrete

     Maximum Area of Reinforcement

For Fy-250, Fy-415, Fy-500 :- 4% of the cross cross-section area of the slab
         = 4% bD   = (4/100)bD

         =0.04bD
In a slab the center to center maximum horizontal spacing between main
reinforcement should not more than 3d OR 300mm
    Whichever is lesser
Where,
d = effective depth of slab.
Maximum spacing between distribution bar should not exceed 5d OR 450mm
   Whichever is lesser
Where, d = effective depth of slab


Important point every civil engineer should know

       Minimum Nominal cover in slab

(i) Diameter of bar if equal bar used, not less than 

(ii) diameter of longer bar if unequal bar are used 

(iii) 15mm

       Whichever is greater

ONE : TWO WAY SLAB
Max diameter of bar In slab =
(1/8 )x over all thickness of slab
Example :- For same loading & Moment condition
No. of Bar =
total steel used/ crossectional area of one bar
10 mm = 1000/78.5 = 12.75 ~ 13 bar
12 mm = 1000/113 = 8.84 ~ 9 bar