Transactions . s a solid one, as shown in thecases of beams Nos. 28 and 29 A. The keys should be so located that the faces receiving a 736 THE EFFICIENCY OF BUILT-UP WOODEN BEAMS. thrust are perpendicular to the joint between the sticks. Wheninclined keys are used, as in Rankines and Bruneis beams, thecomponent pieces slide up the inclined faces of the keys, pryapart the joint, and the benefit of friction between the faces ofthe sticks is lost. Neither great strength nor stiffness can besecured by any form of key not provided with wedges whichcan be firmly driven up. Any other construction, re
Transactions . s a solid one, as shown in thecases of beams Nos. 28 and 29 A. The keys should be so located that the faces receiving a 736 THE EFFICIENCY OF BUILT-UP WOODEN BEAMS. thrust are perpendicular to the joint between the sticks. Wheninclined keys are used, as in Rankines and Bruneis beams, thecomponent pieces slide up the inclined faces of the keys, pryapart the joint, and the benefit of friction between the faces ofthe sticks is lost. Neither great strength nor stiffness can besecured by any form of key not provided with wedges whichcan be firmly driven up. Any other construction, regardless ofthe care used in fitting keys to their slots, leaves more or lessslack, which is taken up as the load is applied, so that the com-ponent parts of the beam slip. The wide range of efficiencies, even in beams of preciselythe same design, shows the impossibility of getting equally closework in every case. In view of the fact that the writer per-sonally built every beam with great care, and that the same. Joist
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
