A structure ABC shown in Figure P$3\mathrm{.}1$ is subjected to a load P acting at A$.$ The column BC of rectangular section has a moment capacity of $160$ kNm and a squash load of $480$ kN$.$ Determine the maximum load P that the column BC can sup$-$ port by assuming failure by $($a$)$ pure bending and $($b$)$ axial$-$bend$-$ ing interaction.