05-03ChapGere.0012 - and is simply supported with span...

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Solution 5.8-7 Laminated wood beam on simple supports 332 CHAPTER 5 Stresses in Beams (Basic Topics) L 5 6 ft 5 72 in. t allow 5 65 psi s allow 5 1800 psi A LLOWABLE LOAD BASED UPON SHEAR STRESS IN THE GLUED JOINTS P 1 5 36 t allow 5 36 (65 psi) 5 2340 lb t 5 ( P / 2)(16 in. 3 ) (72 in. 4 )(4 in.) 5 P 36 Ê ( P 5 lb; t 5 psi) V 5 P 2 Ê I 5 bh 3 12 5 1 12 (4 in.)(6 in.) 3 5 72 in. 4 t 5 VQ Ib Ê Q 5 (4 in.)(2 in.)(2 in.) 5 16 in. 3 A LLOWABLE LOAD BASED UPON BENDING STRESS A LLOWABLE LOAD Shear stress in the glued joints governs. P allow 5 2340 lb P 2 5 4 3 s allow 5 4 3 (1800 psi) 5 2400 lb s 5 (18 P lb-in.) 24 in. 3 5 3 P 4 Ê ( P 5 lb; s 5 psi) S 5 bh 2 6 5 1 6 (4 in.)(6 in.) 2 5 24 in. 3 s 5 M S Ê M 5 PL 4 5 P ¢ 72 in. 4 5 18 P (lb-in.) 2 in . 2 in . 2 in . 2 in . 4 in . N.A. Problem 5.8-8 A laminated plastic beam of square cross section is built up by gluing together three strips, each 10 mm 3 30 mm in cross section (see figure). The beam has a total weight of 3.2 N
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Unformatted text preview: and is simply supported with span length L 5 320 mm. Considering the weight of the beam, calculate the maximum permissible load P that may be placed at the midpoint if (a) the allowable shear stress in the glued joints is 0.3 MPa, and (b) the allowable bending stress in the plastic is 8 MPa. Solution 5.8-8 Laminated plastic beam P 30 mm 30 mm 10 mm 10 mm 10 mm q L P h = 30 mm b = 30 mm 10 mm 10 mm 10 mm 10 mm q L /2 L /2 N.A. L 5 320 mm W 5 3.2 N q 5 W L 5 3.2 N 320 mm 5 10 N / m S 5 bh 2 6 5 1 6 (30 mm)(30 mm) 2 5 4500 mm 3 I 5 bh 3 12 5 1 12 (30 mm)(30 mm) 3 5 67,500 mm 4 A-PDF Split DEMO : Purchase from www.A-PDF.com to remove the watermark...
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This note was uploaded on 09/20/2009 for the course COE 3001 taught by Professor Armanios during the Spring '08 term at Georgia Institute of Technology.

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