Transactions . AM CO., Beams with Oak Driving Keys. Each horizontal space = ^2 Inch deflection. THE EFFICIENCY OF BUILT-UP WOODEN BEAMS. 769 inches wide, secured by eight bolts and eight oakkeys 1 by 2 inches. Span, 66 inches. (See Fig. 25.) Weightof beam, 40 pounds. Broke at 10,600 pounds. Check-pieces-B weighed 17 pounds, broke at 2730 pounds; C weighed 17pounds, broke at 3100 pounds. Efficiency of beam, percent. * No 21. Everything exactly as in No. 20, except that beamweighed 39 pounds. Broke at 6800 pounds. Check-pieces-A weighed 15 pounds, broke at 1920 pounds;
Transactions . AM CO., Beams with Oak Driving Keys. Each horizontal space = ^2 Inch deflection. THE EFFICIENCY OF BUILT-UP WOODEN BEAMS. 769 inches wide, secured by eight bolts and eight oakkeys 1 by 2 inches. Span, 66 inches. (See Fig. 25.) Weightof beam, 40 pounds. Broke at 10,600 pounds. Check-pieces-B weighed 17 pounds, broke at 2730 pounds; C weighed 17pounds, broke at 3100 pounds. Efficiency of beam, percent. * No 21. Everything exactly as in No. 20, except that beamweighed 39 pounds. Broke at 6800 pounds. Check-pieces-A weighed 15 pounds, broke at 1920 pounds; D weighed 16pounds, broke at 2190 pounds. Efficiency of beam, percent. l No. 22. Everything exactly as in No. 20, except that beamweighed 37 pounds. Broke at 8400 pounds. Check-pieces-A weighed 14 pounds, broke at 2100 pounds; D weighed 16 Fig. 25. Oak Keys. I. Joggled Beam with Oak Keys. f-3^ pounds, broke at 2330 pounds. Efficiency of beam, 94 7 percent. l No 23 Everything exactly asin No. 20, except that beamweighed 36 pounds. Broke at 5260 pounds. Check-pieces-A weighed 16 pounds, broke at 2270 pounds; D weighed 14pounds, broke at 2150 pounds. & ^ This beam failed in a previously known flaw on the tension-side before there was any appreciable stress brought to bear onthe keys. The friction of the pieces caused by the pressuredue to bolts took up most of the stress. The failure of thebeam is due to the flaw alone, hence the breaking-strengthin tins case affords no basis for computing efficiency of thejoint. The test is reported merely for sake of the deflection-curves. No 24 Everything exactly as in No. 20, except that beamweighed 36 pounds. Broke at 8660 pounds. Check-pieces: 770 THE EFFICIENCY OF BUILT-UP WOODEN BEAMS. B weighed 16 pounds, broke at 1780 pounds; C weighed 18pounds, broke at 2200 pounds. Efficiency of beam, per
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
