고체역학 (Gere) — Stresses in Beams (Basic Topics): Problem 5.8-5

5.8-5 Two wood beams, each of rectangular cross section (100 mm × 90 mm, actual dimensions), are glued together to form a solid beam with dimensions 200 mm × 90 mm (see figure). The beam is simply supported with a span of 2.5 m. (a) What is the maximum moment \(M_{\text{max}}\) that may be applied at the left support if the allowable shear stress in the glued joint is 1.4 MPa? (Include the effects of the beam’s own weight, assuming that the wood weighs 5.4 kN/m\(^3\).) (b) Repeat part (a) if \(M_{\text{max}}\) is based on allowable bending stress of 17.25 MPa.