고체역학 (Beer) — Analysis and Design of Beams for Bending: Problem 5.144

5.144 Two cover plates, each 7.5 mm thick, are welded to a W460 × 74 beam as shown. Knowing that \( l = 5\text{ m} \) and \( b = 200\text{ mm} \), determine the maximum normal stress on a transverse section (a) through the center of the beam, (b) just to the left of D.