고체역학 (Gere) — Stresses in Beams (Advanced Topics): Problem 6.2-14

6.2-14 A simply supported composite beam with a 3.6 m span supports a triangularly distributed load of peak intensity \(q_0\) at mid-span (see figure part a). The beam is constructed of two wood joists, each 50 mm \(\times\) 280 mm, fastened to two steel plates, one of dimensions 6 mm \(\times\) 80 mm and the lower plate of dimensions 6 mm \(\times\) 120 mm (see figure part b). The modulus of elasticity for the wood is 11 GPa and for the steel is 210 GPa. If the allowable stresses are 7 MPa for the wood and 120 MPa for the steel, find the allowable peak load intensity \(q_{0,max}\) when the beam is bent about the z axis. Neglect the weight of the beam.