고체역학 (Gere) — Stresses in Beams (Advanced Topics): Problem 6.10-3

6.10-3 A propped cantilever beam of length $L = 1.5\text{ m}$ with a sliding support supports a uniform load of intensity $q$ (see figure). The beam is made of steel ($\sigma_Y = 250\text{ MPa}$) and has a rectangular cross section of width $b = 100\text{ mm}$ and height $h = 150\text{ mm}$. What load intensity $q$ will produce a fully plastic condition in the beam?