Problem $4$

The composite compression member whose cross section is shown in the figure below has a

column length $Lx=15ft$ for bending$/$buckling about the $x-x$ axis. For the bending about $y-y$

axis, the column has full lateral support along the column height i$.$e$.,Ly=0ft.$ The column has

pin supports at top and bottom and at lateral support locations $($i$.$e$.Kx=Ky=1\mathrm{.}0).$ The steel

yield strength is Fy $=50$ksi for W $14$ x $53$ and fy $=60$ksi for the $4-$#$9$ longitudinal bars. The

concrete has a compressive strength is f $\text{'}c=5$ksi and $Ec=3900$ksi

Determine $$ Pn for the column

Determine $Mn$ for this column as a flexural member $($i$.$e$.P=0)$ using the three methods

permitted in Section I$3.$