고체역학 (Gere) — Stresses in Beams (Basic Topics): Problem 5.6-10

5.6-10 The wood joists supporting a plank floor (see figure) are 38 mm x 220 mm in cross section (actual dimensions) and have a span length of L = 4.0 m. The floor load is 5.0 kPa, which includes the weight of the joists and the floor. (a) Calculate the maximum permissible spacing s of the joists if the allowable bending stress is 14 MPa. (Assume that each joist may be represented as a simple beam carrying a uniform load.) (b) If spacing s = 406 mm, what is the required depth h of the joist? Assume all other variables remain unchanged.