Design of Shallow Foundation (Isolated Footings)
Back calculation in excel file-
Shear force in the two-way shaded area= [(3.6X3.6)-(0.85X0.85)] X 154.321 = 1888.503 ~ 1889 KN
Design shear stress at two way cut face τv= (1889X1000)/(3400X450) = 1.234 N/mm^2
Shear stress capacity of section as per IS-456:2000 Clause 31.6.3.1
Design shear stress is less than shear capacity.
Hence okay.
Result:-
Sloped isolated footing for a square column has been designed with the given specification
Calculation of stepped footing
Critical distance of One-way shear from column face = 450mm
Critical distance of Two-way shear from column face = 225mm
We have to provide 500mm footing thickness at least 450mm from column face, rounding it off to 500mm uniform around the column, as shown below.
Schematic Representation of Footing step and reinforcement:
Conclusion:-
Thus the required spread footing is designed and detailed as per given inputs. All the required limit state criteria are verified and found to OK.