$4\mathrm{.}7-10$ The rigid frame shown in Figure P$4\mathrm{.}7-10$ is unbraced. The members are ori$-$

ented so that bending is about the strong axis. Support conditions in the dir$-$

ection perpendicular to the plane of the frame are such that $K_y=1\mathrm{.}0.$ The

beams are W$1850,$ and the columns are W$1272.$ A$992$ steel is used. The

axial compressive dead load is $50$kips, and the axial compressive live load is

$150$ kips.

a$.$ Determine the axial compressive design strength of column $AB.$ Use the

stiffness reduction factor if applicable.

b$.$ Determine the allowable axial compressive strength of column $AB.$ Use$-$

the stiffness reduction factor if applicable.