고체역학 (Beer) — Pure Bending: Problem 4.202

4.202 A short length of a W8 × 31 rolled-steel shape supports a rigid plate on which two loads P and Q are applied as shown. The strains at two points A and B on the centerline of the outer faces of the flanges have been measured and found to be \(\epsilon_A = -550 \times 10^{-6}\) in./in., \(\epsilon_B = -680 \times 10^{-6}\) in./in. Knowing that \(E = 29 \times 10^6\) psi, determine the magnitude of each load.