8-8.  A steel angle has a cross-section area of . The smallest redius of gyration occurs about the u-u axis and is . The angle is 12-ft-long and is pin-connected in a system. Assume that the modulus of elasticity follows . Determine the distribution of the critical axial buckling load that can be applied through its centroid C.

Solution:

The critical stress is

,       where .

The critical axial buckling load is

Since , we have

Thus, the critical axial buckling load follows .                                       Ans.