CHAPTER XL 
proportioning of main members of trusses, 
lateral systems, and sway bracing. 
TT . 
tli 】 aVU 】g f ouu( l 心 tlie stresses in the main members of the truss ami in those of 
a era l systems and sway bracing, and haying written them alongside the res- 
幻扣 1 ' ぶ . mem bers iu tlie diagrams, the next step is to calculate the sections required. 
la o l，a ^s for the lateral systems and sway bracing may bo roughly drawn in 
。 二 1 ’ foi they need not be preserved, as the sizes cf the members are to be written 
0U the truss diagram. 
^ Foi the ten 81011 members cf tho trusses, tlie sections required can be found by 
lc the stresses on Ihc diagram by the proper intensities of working-stress, as 
^ f U 111 ^ ia ptor VI, remembering that the intensities for main diagonals are to 
11 eipolated. When found, the required areas for the sections should bo written 
} e diagram， after the stresses, prefixing them with the letters S. E. ( section 
そ U : e d)， as sliown on plate XV. It must not bo forgotten that the sections i e- 
わ 1 山 6 ^°^ om e h or d s must be calculated for live and dead load a tresses 
s い aU : u t en8 ity of five tons aud for combined live load, dead load rm ( し wind 
tabl SSGS, au iu tensity of seven and a lialf tons. Then, by using the proper 
. es 111 Clmpfcei’ II， there Cfiu be found the sizes of tension members which will 
ive at leaM the section required. 
e . 8 lesses in tlie counters are to bo increased for initial tension by the amounts 
^ GU . m Chapter YI ， oi. wliat amounts to the same thing, the size require 1 can be 
Sti；: L f 10lu fahle VI. by looking dowii the column heatlotl 4< Iuteusifcy of Working 
jss — i tons ’’ until a stress is readied which is equal to or greater than one-lialf 
e 、 v l 10 】 e of tlie stress on the diagram, according to wliotlier double or siiiglo 
^uuteis be employed ； then, by following the horizontal line which contains this 
ess ’ either to right or left, will be found the size of the counters or counter 
required. 
fhe sizes of lap verticals can be fouucl without calculation from Table YII. 
. 11 P 0n y trusses having less than five panels it is necessary to make them stiffened, 
^sing either trussed bars or two channels laced or latticed. 
. stated iu Chapter YI, if the former be employed tlio intensity of working stress 
. be l educed to three tons, and, if the latter, tlie effective area of the webs alone 
ls o be relied upon to resist tension. 
