A simply supported wooden I-beam with a 12 ft span supports a distributed load of intensity q = 90 lb/ft over its length (see figure part a). The beam is constructed with a web of Douglas-fir plywood and flanges of pine glued to the web as shown in the figure part b. The plywood is 3/8 in. thick; the flanges are 2 in. x 2 in. (actual size). The modulus of elasticity for the plywood is 1,600,000 psi and for the pine is 1,200,000 psi.
(a) Calculate the maximum bending stresses in the pine flanges and in the plywood web.
(b) What is qmax if allowable stresses are 1600 psi in the flanges and 1200 psi in the web?

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12 ft 2 in. X 2 in. pine flange NK in. 2 in 8 in in. plywood Douglas fir) 8 in. -2 In