1. Footing

2. Failures
1.Bearing failure
2.Serviceability failure
3.Excessive total settlement

3. P M
Centroidal Axis
P/A
My/I

4. L/6
Kern L B

5. Pc=0
240 lb/ft2
300 lb/ft2
540 lb/ft2

6. Pc
240 lb/ft2
2 ft of lb/ft3
300 lb/ft2
2 ft of lb/ft3
540 lb/ft2
Gross soil pressure =
540+qn lb/ft3
qn=Pc/A

7. P M
Net soil pressure
qn=Pc/A

8. Only Dead load and Live load
Area of footing
Including Wind load also
Area of footing or

9. Isolated footing with axial load and moment
Design Input
Grade of concrete
Grade of steel
Allowable soil pressure
Column load
Moment
Condition about overburden of soil

10. Design procedure Checking the footing area Assume column size
Assume footing size
Total load=wt of footing+column load
Average soil pressure q= total load / footing area
Allowable soil pressure > Average soil pressure
then footing are is ok

11. Finding factored loads
Factored column load=1.4xdead load+1.7xlive load
Average factored soil pressure qnet=Factored column load/footing area
Average dv=total thick – cover - bar dia
Eccentricity e=Mu/Pu
Solving two equations to get q1 and q2
Service load equation
Vertical equilibrium

12. Check for One way shear Check for Two way shear
Take the critical section as ‘d’ distance from the
face of the column (as per ACI 318 )
1.find pressure at critical section
2.find Vu
3.find Vu
If Vu>Vu
Check for Two way shear
Take the critical section as ‘d/2’ distance all around
the face of the column (as per ACI 318 )
find pressure at critical section
Find the value of bo
2.find Vu
3.find Vu is smallest of these

13. Safe against two way shear
Otherwise increase the depth

14. Check for flexural reinforcement
Max moment occurs at the face of the column
Find average pressure
Find required moment Mn=Mu/
Find required Ast
Min Ast=0.0018bh
Max spacing=18 in
Development length

15. Thank You