고체역학 (Beer) — Pure Bending: Problem 4.103

4.103 As many as three axial loads, each of magnitude \( P = 50 \text{ kN} \), can be applied to the end of a W200 \(\times\) 31.1 rolled-steel shape. Determine the stress at point \( A \), (a) for the loading shown, (b) if loads are applied at points 1 and 2 only.