Week 12 Challenge
Q1) ISOLATED FOOTING
Isolated footing for a column 300 mm x 450 mm, carrying axial load of 1500 kN and Mu = 150 kNm ( Reversible) . The safe bearing capacity of the soil is 200 kN/m2 at a depth of 1 metre from ground level.
Grade of concrete - M 25 and
Grade of steel - Fe 415.
Open stadd foundation, general mode.
Add first column coordinates in the origin (0,0,0)
Create column position from foundation plan.
Add load cases to the footing column.
Assign the loads.
Create load combinations.
Create new job for Isolated footing and assign design parameters
Stadd file attached for reference.
Dimension of footing:
1) 4.35 mx 4.35 m
2) Over all depth of footing D =560 mm
3) Depth of footing is checked for BM, Single shear & Double shear and found safe
4) No tension steel is needed as there is no negative pressure.
5) Development length = 648 mm
VALIDATION OF DESIGN THROUGH HAND CALCULATION
Q2) COMBINED FOOTING
Given data :
Combined footing is required to be designed for-
1. two columns C1 and C2 having size 400 mmx 400 mm & 300 mmx 500 mm respectively.
2. Service load on C1 is 800 KN & on C2 is 1200 KN
3. Column C1 is flushed with property line
4. c/c distance between columns = 3.0 m
5. SBC of soil = 200 KN/m^2 at a depth of 1.5 m
6. Grade of Concrete : M20
7. Steel grade : Fe 415
Set up coordinates and units by opening general mode in Stadd foundation.
Column C1 & C2 are placed at a distance of 3 m and their dimensions are 400 mmx 400 mm & 300 mm x 500 mm.
Adding and assigns loads and load combinations 
Create combined strip footing in edit job option 
Footing thus designed
Stadd file attached for reference
Design is successful with footing dimension as 7m x 4.5 m and thickness 0.5 m. Both columns left and right over hang is 2m each side.
main steel top 12mm dia bar @ 165 mm c/c
main steel bottom 12 mm dia bar @ 80 mm c/c
secondory steel bottom 12 mm dia 85 mm c/c and top 12 mm dia 170 mm c/c
Design is safe against sliding , single shear , punching shear, soil pressure, overturning