Transactions . rties who had used forms of key not included in thetests. The writer, therefore, pursued the investigation further,with results that will now be given. Diagram 13 shows deflection of beams Kos. 41 to 50, inclu- THE EFFICIENCY OF BUILT-UP WOODEN BEAMS. 785 sive. The writer believes that Nos. 39 to 47 could be mademuch stifter by the simple expedient of providing the keys witha taper of about one-eighth of an inch, then driving them firmlyinto place after the component sticks had been tightly boltedup. In such cases the larger end of the keys should*be pro-vided with an ear or lug
Transactions . rties who had used forms of key not included in thetests. The writer, therefore, pursued the investigation further,with results that will now be given. Diagram 13 shows deflection of beams Kos. 41 to 50, inclu- THE EFFICIENCY OF BUILT-UP WOODEN BEAMS. 785 sive. The writer believes that Nos. 39 to 47 could be mademuch stifter by the simple expedient of providing the keys witha taper of about one-eighth of an inch, then driving them firmlyinto place after the component sticks had been tightly boltedup. In such cases the larger end of the keys should*be pro-vided with an ear or lug, arranged so that an ordinary wood-screw can pass through a hole or slot in the lug, screw intothe beam, and thereby prevent the key from shaking out of itsslot under heavy vibrations, etc. Beams with T-shaped Keys of 39. Two pieces of white pine, inches thick and 4 5inches wide, secured as in Fig. 35. Keys of cast-iron as inFig. 36. Span, 90 inches. Weight of beam, 44 pounds. Broke Fig. Clear span 90 inches Beams with Keys Cut from Carnegie T-Sections, No. 21 and 95. *1 at 5700 pounds. Check-pieces: B weighed 17 pounds, brokeat 2360 pounds: C weighed 17 pounds, broke at 2300 of beam, per cent. No. 40. Same as No. 39. Weight of beam, 40 pounds. Brokeat 7400 pounds. Check-pieces same as preceding two. Ef-ficiency of beam, Average for the two beams, percent. Deflection of these two beams was not noted. Beams with T-shaped Keys of Steel. No. 41. Two pieces of white pine, inches thick and 4 5 inches wide, secured by bolts and keys made by sawing off pieces of Carnegie T-section, No. 21.* These keys were ground ft^rbmrs^mi^ end, the slots carefully cut to size for a * See Pocket Companion. Carnegie, Phipps & Co. Edition of 1892. 786 THE EFFICIENCY OF BUILT-UP WOODEN BEAMS. driving lit, and keys were then driven home after the beam wasbolted up. (See Fig. 37.) Dimensions of key are shown inFig. 38. Span of beam, 90 inche
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
