MAXIMUM SIZE OF CONCRETE SLAB, BEAM & COLUMN  CALCULATION
In This Article, We Will Explain About Maximum Size
Of Concrete Slab, Beam & Column Calculation
MAXIMUM SPAN/LENGTH OF THE BEAM
MAXIMUM DEPTH OF THE BEAM
The maximum span & depth of a beam (cantilever / simply
supported / continuous) are decided by deflection limits
These deflection limits are defined in terms of L/d ratio,
where ‘L’ is the effective span & ‘d’ is
the effective depth of the beam member.
According To Is
Code On Clause 23.2.1 of IS: 456 (2000)
pg. no. 37 The same provisions are stipulated for beam spans of up to 10 m.
Cantilever; Span/d <= 7
Simply supported; Span/d <= 20
Continuous; Span/d <=26
Greater than 10m
Simply supported < = 20x10/span
Continuous < = 26x10/span
Thus, depending on the length
provided, the minimum allowable
depth of the beam member can be calculated, and likewise the maximum allowable span can be
calculated using the L/d ratio for a
given depth of the beam member.
Note:
Effective Span: Usually the c/c
span of the beam member is taken into account for further reference. See clause 22.2 of IS:456 (2000) pg. 34
Effective depth: d = D  (cover)
(dia of bottom bar/2)
D = effective depth
D = overall depth
ALSO
READ: Minimum
Size Of Concrete Slab, Beam & Column
MAXIMUM THICKNESS OF THE SLAB
Standards such as ACI 318 specify the minimum thickness
of the slab based on the length of the slab.
·
Simply
Supported Slab = L / 20
·
One
End Continuous Slab = L / 24
·
Both
End Continuous Slab = L / 28
·
Cantiliver
= L / 10
However,
in other criteria, they do not directly specify the minimum slab thickness.
MINIMUM
THICKNESS OF THE SLAB AS PER IS 456:2000 

Simply supports slabs spanning in one direction 
L/30 
Simply supports slabs spanning in Two directions (Twoway slab) 
L/35 
Continuous slabs spanning in one direction 
L/35 
Continuous slabs spanning in Two direction 
L/40 
Cantilever slabs 
L/12 
ALSO
READ: Minimum
And Maximum Spacing Of Beam, Column, Stirrups, Slab & Footing
MAXIMUM
ALLOWABLE HEIGHT OF A COLUMN WITHOUT ANY BRACE OR TIE
Columns can build as long column fails by
buckling.
So if the slenderness ratio of the column is greater than 12, that the column is classified as a long column.
Slenderness ratio=L(eff)/R(min)
L (efff) has to be determined as per IS
456:2000
R (min) = ( I(min) /Area of crosssection
)^{1/2}
But simply it can be understood as if column size is of 250X 250
mm then as per slenderness ratio limit if 12
Therefore,
Slenderness
ratio = Length /shorter dimension
i.e., 12= length/250
i.e., Length= 12 x 250=3000 mm
So if you make a column of size 250mm x 250mm it should
not exceeds the height of 3m. if you need to build beyond it. It needs tie beams
MAXIMUM COLUMN SIZES FOR DIFFERENT
STORIES
S.NO 
NO. OF STORY 
SIZE 
1 
12 
230mm x 230mm 9” x 9” 
2 
13 
300mm x 300mm 12”x12” 
3 
110 
750mm x 750mm 30” x 30” 
4 
120 

17 
800mm x 800mm 32” x 32” 

815 
600mm x 600mm 24” x 24” 

1620 
450mm x450mm 18” x 18” 

5 
130 

110 
850mm x 850mm 34” x 34” 

1120 
650mm x 650mm 26” x 26” 

2030 
475mm x475mm 19” x 19” 
NOTE:
These are the standard RCC column sizes, but it will increase or decrease with
respect to the load.
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