. The railroad engineer's practice . re, we have^u = .72,and cost of one-half truss =$ If, in the last case, how-ever, we make A = 12 and A = 20, we have m =.73 and costof one-half truss = $,which shows the result of using 139 pieces of large diameter in the compression parts. Itwould seem, then, that when only small scantlings can beobtained, it would be better to make a large number ofpanels, and when large scantlings arc procurable, to in-crease the length of the panels. It should be observed,however, that the load is supposed to be applied to thetruss only at the panel points.
. The railroad engineer's practice . re, we have^u = .72,and cost of one-half truss =$ If, in the last case, how-ever, we make A = 12 and A = 20, we have m =.73 and costof one-half truss = $,which shows the result of using 139 pieces of large diameter in the compression parts. Itwould seem, then, that when only small scantlings can beobtained, it would be better to make a large number ofpanels, and when large scantlings arc procurable, to in-crease the length of the panels. It should be observed,however, that the load is supposed to be applied to thetruss only at the panel points. As a matter of fact, it isusually applied on a chord, and the additional materialrequired in the chord on this account would be propor-tionately greater in a long panel than in a shorter is better, however, to use separate i)ieces to support theload between the panel points, and so confine the chordsto their legitimate duty of resisting the stresses in thedirection of their lengths due to the structure acting as atruss
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