507_Mechanics SolutionInstructors_Sol.Manual-Mechanics_Materials_7e.book_Gere_light.1

# 507_Mechanics SolutionInstructors_Sol.Manual-Mechanics_Materials_7e.book_Gere_light.1

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SECTION 6.2 Composite Beams 501 Problem 6.2-5 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 M 0 ± 300 ft-lb at joint B . The beam consists of a wood member (nominal dimensions 6 in. ² 12 in., actual dimensions 5.5 in. ² 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 E s ± 30 ² 10 6 psi and E w ± 1.5 ² 10 6 psi, respectively. (a) Calculate the maximum bending stresses s s in the steel plates and s w in the wood member due to the applied loads. (b) If the allowable bending stress in the steel plates is s as ± 14,000 psi and that in the wood is s aw ± 900 psi, find q max . (Assume that the moment at B, M 0 , remains at 300 ft-lb.) (c) If q ± 660 lb/ft and allowable stress values in (b) apply, what is M 0,max at B ? 11.5 in. (a) (b) M 0 5 ft 5 ft q AC B 0.25 in. 5.5 in. 0.25 in. z y C Solution 6.2-5 (a) M AXIMUM BENDING STRESSES Wood (1): b ± 5.5 in.
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## This note was uploaded on 12/22/2011 for the course MEEG 310 taught by Professor Staff during the Fall '11 term at University of Delaware.

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