476_Mechanics SolutionInstructors_Sol.Manual-Mechanics_Materials_7e.book_Gere_light.1

476_Mechanics SolutionInstructors_Sol.Manual-Mechanics_Materials_7e.book_Gere_light.1

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470 CHAPTER 5 Stresses in Beams (Basic Topics) Solution 5.11-6 Two wood box beams Cross-sectional dimensions are the same. All dimensions in millimeters. allowable load per nail shear force longitudinal spacing of the nails shear flow between one flange and both webs f ± 2 F s ± VQ I s max ± 2 FI VQ f ± s ± I ± 1 12 ( bh 3 ² b 1 h 1 3 ) ± 340.69 * 10 6 mm 4 ± 3.2 kN V ± ± 250 N F ± t ± 20 h ± 360 h 1 ± 360 ² 2(20) ± 320 b ± 200 b 1 ± 200 ² 2(20) ± 160 (a) B EAM A (b) B EAM B (c) B EAM B IS MORE EFFICIENT because the shear flow on the contact surfaces is smaller and therefore fewer nails are needed. ; ± 97.9 mm ; s B ± 2 FI VQ ± (2)(250 N )(340.7 * 10 6 mm 4 ) (3.2 kN)(544 * 10 3 mm 3 ) ± 544 * 10 3 mm 3 ± (160)(20) 1 2 (340) Q ± A f d f ± ( b ² 2 t )( t ) a h ² t 2 b ± 78.3 mm ; s A ± 2 FI VQ ± (2)(250 N)(340.7 * 10 6 mm 4 ) (3.2 kN)(680 *
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Unformatted text preview: 10 3 mm 3 ) ± 680 * 10 3 mm 3 Q ± A f d f ± ( bt ) a h ² t 2 b ± (200)(20) a 1 2 b (340) Problem 5.11-7 A hollow wood beam with plywood webs has the cross-sectional dimensions shown in the figure. The plywood is attached to the flanges by means of small nails. Each nail has an allowable load in shear of 30 lb. Find the maximum allowable spacing of the nails at cross sections where the shear force is equal to (a) 200 lb and (b) 300 lb. V s z y O 3 in. — in. 3 16 — in. 3 16 8 in. in. 3 4 in. 3 4 05Ch05.qxd 9/25/08 2:29 PM Page 470...
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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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