Gere & Goodno — Stresses in Beams (Basic Topics): Problem 5.8-10

5.8-10 A laminated plastic beam of square cross section is built up by gluing together three strips, each 10 mm $\times$ 30 mm in cross section (see figure). The beam has a total weight of 3.6 N and is simply supported with span length $L = 360$ mm. Considering the weight of the beam ($q$), calculate the maximum permissible CCW moment $M$ that may be placed at the right support. (a) The allowable shear stress in the glued joints is 0.3 MPa. (b) The allowable bending stress in the plastic is 8 MPa.