A simple beam that is 18 ft long supports a uniform load of intensity q. The beam is constructed of two C 8 x 11.5 sections (channel sections or C shapes) on either side of a 4 x 8 (actual dimensions) wood beam (see the cross section shown in the figure part a). The modulus of elasticity of the steel (Es = 30,000 ksi) is 20 times that of the wood (Ew).
(a) If the allowable stresses in the steel and wood are 12,000 psi and 900 psi, respectively, what is the allowable load qallow?
(b) If the beam is rotated 90° to bend about its y axis (see figure part b), and uniform load q = 250 lb/ft is applied, find the maximum stresses σs and σw in the steel and wood, respectively. Include the weight of the beam. (Assume weight densities of 35 lb/ft3 and 490 lb/ft3 for the wood and steel, respectively.)

Transcribed Image Text:

C8 x 11.5 z C 8 x 11.5 1 Wood beam Wood beanm