05-05ChapGere.0003

05-05ChapGere.0003 - F 5 250 lb per screw. Calculate the...

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Problem 5.11-4 A box beam of wood is constructed of two 260 mm 3 50 mm boards and two 260 mm 3 25 mm boards (see figure). The boards are nailed at a longitudinal spacing s 5 100 mm. If each nail has an allowable shear force F 5 1200 N, what is the maximum allowable shear force V max ? Solution 5.11-4 Wood box beam 352 CHAPTER 5 Stresses in Beams z y O 50 mm 25 mm 25 mm 50 mm 260 mm 260 mm All dimensions in millimeters. b 5 260 b 1 5 260 2 2(50) 5 160 h 5 310 h 1 5 260 s 5 nail spacing 5 100 mm F 5 allowable shear force for one nail 5 1200 N f 5 shear flow between one flange and both webs Q 5 Q flange 5 A f d f 5 (260)(25)(142.5) 5 926.25 3 10 3 mm 3 5 10.7 kN V max 5 f allow I Q 5 (24 kN / m)(411.125 3 10 6 mm 4 ) 926.25 3 10 3 mm 3 I 5 1 12 ( bh 3 2 b 1 h 3 1 ) 5 411.125 3 10 6 mm 4 f 5 VQ I Ê V max 5 f allow I Q f allow 5 2 F s 5 2(1200 N) 100 mm 5 24 kN / m Problem 5.11-5 A box beam constructed of four wood boards of size 6 in. 3 1 in. (actual dimensions) is shown in the figure. The boards are joined by screws for which the allowable load in shear is
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Unformatted text preview: F 5 250 lb per screw. Calculate the maximum permissible longitudinal spacing s max of the screws if the shear force V is 1200 lb. Solution 5.11-5 Wood box beam z y O 1 in. 1 in. 1 in. 1 in. 6 in. 6 in. All dimensions in inches. b 5 6.0 b 1 5 6.0 2 2(1.0) 5 4.0 h 5 8.0 h 1 5 6.0 F 5 allowable shear force for one screw 5 250 lb V 5 shear force 5 1200 lb s 5 longitudinal spacing of the screws f 5 shear flow between one flange and both webs Q 5 Q flange 5 A f d f 5 (6.0)(1.0)(3.5) 5 21 in. 3 5 3.65 in. s max 5 2 FI VQ 5 2(250 lb)(184 in. 4 ) (1200 lb)(21 in. 3 ) I 5 1 12 ( bh 3 2 b 1 h 1 3 ) 5 184 in. 4 s max 5 2 FI VQ f 5 VQ I 5 2 F s A-PDF Split DEMO : Purchase from www.A-PDF.com to remove the watermark...
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