Two $500mm$ by $500mm$ reinforced concrete columns $($columns $1$ and $2)$ are located at $3\mathrm{.}9$ m centre$-$to$-$centre sparing, as shown in the figure below, Due to its proximity to the property line, the column $2$ footing can be extended by al maximum of $0\mathrm{.}6m$ beyond the column vertical axis on the left side. It is therefore required to design a combined footing to support both columns. The column loads are shown on the slefch below $($note that the column $1$ loads are the same as discussed in Exampleha. $3$ in relation to a spread footing design$).$ Use a $6m$ long by $3m$ wide combined footing for this design and $25M$ bars for fexural reinforcement. Maximum aggregate size is $20mm.$ Ignore the effect of pattern loading in the deslgn.

Design the combined fooling acconding to the CSA A$23\mathrm{.}3$ requirements.

Given:

$f_c^{\text{'}}=25$MPa $(normal-$densily concreme$)$

$f_y=400$MPa

${}_c=0\mathrm{.}65$

${}_r=0\mathrm{.}85$