Example:

Design a combined footing to support the two columns $A($exterior$)$ and $B($interior$)$ spaced at distance $6\mathrm{.}0m$ center$-$to$-$center as shown in the figure. Column $A$ is $0\mathrm{.}4mx0\mathrm{.}4m$ and carries a dead load of $500kN$ and a live load of $300kN.$ Column B is also $0\mathrm{.}4m0\mathrm{.}4m$ in cross section but carries a dead load of $750kN$ and a live load of $450kN.$ Use $f_c^{\text{'}}=25$MPa,$f_y=420$MPa, and qall$(net)=150k\frac{N}{m^2}$