When to use: Evaluate the compressive capacity of an axially loaded steel column against flexural buckling. Computes the classic Euler critical load Pcr, the slenderness ratio KL/r, and the AISC 360 Chapter E (E3) design strength φPn. The transition limit 4.71√(E/Fy) determines whether the member buckles in the inelastic or elastic range. Use the effective length factor K to capture end conditions.