. Practical structural design; a text and reference work for engineers, architects, builders, draftsmen and technical schools;. int of the endbrace, where it is set into the chord, and there is consequently aprojection, 26 - = ins. beyond the center of the sup-porting wall or column. This may be concealed by corbelling outthe brickwork of the wall, but very often such a projection isobjectionable. Designers who do not think clearly will often placethe support under the very end of the projecting piece, and thissets up bending moments which will cause the chord to break. Assume, for
. Practical structural design; a text and reference work for engineers, architects, builders, draftsmen and technical schools;. int of the endbrace, where it is set into the chord, and there is consequently aprojection, 26 - = ins. beyond the center of the sup-porting wall or column. This may be concealed by corbelling outthe brickwork of the wall, but very often such a projection isobjectionable. Designers who do not think clearly will often placethe support under the very end of the projecting piece, and thissets up bending moments which will cause the chord to break. Assume, for example, in the present instance that the centerline of the support is 6 ins. from the end of the projecting leaves 20 ins. to the deepest cut and ins. to the verticalline from the center of the face of the brace. The bending moment= X 25,000 = 464,500 in. lbs. The vertical moment armbetween the compression and tension area is 4 ins. and the area ofthe tension side below the cut = 8 X = sq. ins. JOINTS AND CONNECTIONS 169 The tensile stress = 464,500 = 2807 lbs. per sq. in., and the 34000. 4 X allowable stress is 1600 lbs. per sq. in., therefore the center lineof the support cannotbe so far from theend of the brace. Theproper position, in or-der to keep all forcesin equilibrium, is left of the bottompoint of the end tension caused bymoving the supportfarther to the leftmust be added to thetension in the chord;so the actual stress, if ^ig. 99-Desigii for Joint Lo the support is away at the end, = ( X 2807) + 25,000 =141,098 lbs. In Fig. 99 is shown another method of forming the joint, thetoe cut not being perpendicular (normal) to the line of angle at the toe is 75 degrees and the angle of the slopingbottom of the cut is 16 degrees; for the angle between the sur-faces may vary, it not being necessary to have the lower pointa right angle. Computations will be made to obtain the area ofthe pressed surface a
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