A horizontal beam AB is pin-supported at end A and carries a load Q at end B,

Question:

A horizontal beam AB is pin-supported at end A and carries a load Q at end B, as shown in the figure. The beam is supported at C by a pinned-end column of length L; the column is restrained laterally at 3.0L from the base at D. Assume the column can only buckle in the plane of the frame. The column is a solid steel bar (E = 200 GPa) of square cross section having length L = 2.4 m side dimensions b = 70 mm. Let dimensions d = L/2. Based upon the critical load of the column, determine the allowable moment M if the factor of safety with respect to buckling is n = 2.0.