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. x 12 in., actual dimensions 5.5 in. x 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 x 106 psi and Ew = 1.5 x 106 psi, respectively.
(a) Calculate the maximum bending stresses σs in the steel plates and σw in the wood member due to the applied loads.
(b) If the allowable bending stress in the steel plates is σas = 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?

Transcribed Image Text:

0.25 in 11.5 in ILI 0.25 in. 5.5 in.