A beam with a guided support and 10 ft span supports a distributed load of intensity q = 660 lb/ft over its first half (see figure part a) and a moment M0= 300 ft-lb at joint B. The beam consists of a wood member (nominal dimensions 6 in. ×12 in., actual dimensions 5.5 in. × 11.5 in. in cross section, as shown in the figure part b) that is reinforced by 0.25-in.-thick steel plates on top and bottom. The moduli of elasticity for the steel and wood are Es= 30 ×106 psi and Ew= 1.5 × 106 psi, respectively.
(a) Calculate the maximum bending stresses σs in the steel plates and #w in the wood member due to the applied loads.
(b) If the allowable bending stress in the steel plates is as 14,000 psi and that in the wood is σaw = 900 psi, find qmax. (Assume that the moment at B, M0, remains at 300 ft-lb.)
(c) If q = 660 lb/ft and allowable stress values in (b) apply, what is M0,max at B?
