Design of Sloped Square footing
Ref
Step
Calculations
1.0 Initial Input data
Unfactored Axial load of Column:
Column Width:
Column Depth:
Concrete Grade:
Steel Grade:
Soil Bearing Capacity:
Output
409.04
304.800
304.800
20.000
500.000
120
kN
mm
mm
N/mm2
2
N/mm
2
kN/m
409.040
10.000
449.944
1.936
1.981
kN
2.0 Size of the Footing
Net Weight
Assumed footing weight % ,
Gross Footing weight,
Footing width
Adopted width/length
IS 456
Cl.34.2.2
Providing a square ledge
609.570 mm
around the coulmns.
3.0 Ultimate loads from column
Factored load:
Upward pressure:
SP 16
kN
m
m
4.0 Depth from moment consideration
Taking moment about face of the column
For a conservative estimate of (d)
Mxx= P/8L*(B-d)2
B:
b:
Mxx:
Breadth Resisting Moment:
For Fe 415, Mu=0.138fckbd2
613.560 kN
0.156 N/mm2
1981.200
304.800
1.088E+08 N/mm2
609.570 mm
For Fe 500, Mu=0.133fckbd2
0.133
d:
Provided effective depth at column face
Provide depth at edge of footing
Provided cover for steel
259.027
350.000
200.000
50.000
mm
mm
mm
mm
5.0 Check depth from one way shear
IS 456
Take section at effective depth from the face of the column
Cl 34.2.4.1 a
minimum dimension of column
304.800
Distance of section from edge of
footing equals to( Along minimum
dimension of column:
488.200 mm
o
Breadth of column face at this section with 45 diagonal
b1
1004.800 mm
V1
113.935 kN
effective depth of section d1
289.787 mm
Size of Footing
Length: 6 '- 6.0'' ft
Breadth: 6 '- 6.0'' ft.
2.00
ft
Design of Sloped Square footing
Ref
Step
Calculations
Output
IS 456
c(required)
2
0.391 N/mm
For Grade 20 with nominal steel
Concrete design shear strength
2.800 N/mm2
Cl 34.2.4.1 b
From IS 456
Table 20
Safe in one way shear
6.0 Check for Two way shear
Section at d/2 from face of column
IS 456
Cl 34.2.4.1(b)
d/2:
Distance of section from edge of footing:
b2:
d2
V2
p:
IS 456
Cl 31.6.3.2
175.000
663.200
654.800
321.972
546537.9
mm
mm
mm
mm
N
2
0.648 N/mm
Shear Capacity of concrete
c=0.25fck
1.118 N/mm
Safe in Two way shear
7.0 Area of steel required
For a economical solution is to take moments of the pressures
inside the diagonals
Mx=P/24LB(2L+a)(B-b)2
Mx:
M/(fck b d2)
From Table
78.11 kN-m
0.052 mm2
Lever Arm factor
As=Mu/0.87fydLa
0.92
Area of steel required:
557.6 mm2
Assume bar dia meter
#of bars
Area of total bars
12.0 mm
10.0 nos.
1131.0 mm2
8.0 Distribution of steel-Check for Spacing
Distribute total steel uniformly as per IS.
Provide cover to effective depth of
Hence, Spacing
spacing less than 300
50.000 mm
209.022 mm
spacing less than 3d
9.0 Check for development Length
Required Ld:
684.000 mm
Available Length:
685.815 mm
sufficient development length
no. bars sufficient
2
Steel provided1130.97 mm
50 mm side cover
Spacing = 209.02
Design of Sloped Square footing
Ref
Step
Calculations
10.0 Overall Dimension of the footing
L=B=
at edge of footing to
at face of column
Output
1981.200 mm
250.000 mm
400.000 mm
depth of footing at the edge
250.00 mm
depth of footing at the face
of column
400.00 mm
Modifying Area of steel on full breadth and mean depth
Mean depth considering the whole width:
298.076 mm
2
SP 16 Table 1
M/bd :
p:
As:
Assume bar diameter:
# of bars
Provided Area of total bars
Hence, Spacing is
0.444
0.106 %
625.981 mm2
12.0
10.0
1131.0
209.022
mm
nos.
mm2
mm
no. bars sufficient
Spacing = 8.23
inch
