Effective Length Problem

The rigid frame shown below is unbraced. The members are oriented so that bending is about the strong axis. Support conditions in the direction perpendicular to the plane of the frame are such that $Ky=1\mathrm{.}0.$ The beams are W$18\backslash$times $50,$ and the columns are W$12\backslash$times $72.$ A$992$ steel is used. The axial compressive dead load is $50$kips, and the axial compressive live load is $150$kips. Determine the axial compressive design strength of column AB$.$ Use the stiffness reduction factor if applicable.