. Practical structural design; a text and reference work for engineers, architects, builders, draftsmen and technical schools;. ace of the normal cut. Theunit stress on the fibers of thechord, is found as shown inthe design of the cut for theend brace. The depth of thecut is then found. At theupper end the normal (rightangle) cut is on the lowerside of the strut and at the lower end it is on the upper lines through the centers of these normal areas, parallelwith the top and bottom of the strut. The eccentricity is thedistance between these center lines. Multiply the thrust by the ecc
. Practical structural design; a text and reference work for engineers, architects, builders, draftsmen and technical schools;. ace of the normal cut. Theunit stress on the fibers of thechord, is found as shown inthe design of the cut for theend brace. The depth of thecut is then found. At theupper end the normal (rightangle) cut is on the lowerside of the strut and at the lower end it is on the upper lines through the centers of these normal areas, parallelwith the top and bottom of the strut. The eccentricity is thedistance between these center lines. Multiply the thrust by the eccentricity in inches and get thebending moment in inch pounds. This has a tendency to makethe end of the strut move on the face of the normal cut andjump out. It must be resisted by the friction of the wood onthe face of the cut. Divide the eccentric moment by the lengthof the strut in inches and this gives the force to be developed byfriction. Assuming the coefficient of wood against wood, forshding friction, to be , multiply the direct thrust by andobtain the resistance the wood will offer against being forced out. Fig. 108—Intermediate Joints withNormal Cuts JOINTS AND CONNECTIONS 183 of the cut by the bending moment. Nails and spikes offer resist-ance against being pulled out, so if the ends of the strut are Hoenailed this additional resistance will be good. It seldom happensthat the eccentric moment divided by the length of the strut willgive an amount exceeding the direct thrust multiphed by the co-efficient of friction, but if it does then spikes or bolts must be. used to hold the toe in place. Carelessness in keeping all jointstight reduces the effect of friction, and decay in the joint alsoseriously affects it. In the joints illustrated there is often aserious loss in the efficiency of the upper and lower chords becauseof the depth of the indent. Details tending to reduce cuttinginto chords should be favored. It has been said that all forces should act through
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