— 101 — 
^leased weight iv 4 upon the windward truss aiul an increased weight of the same 
amount upon the leeward truss, which will give the equation 
2) Ji = w 4 b 
or n\ = ~ 
An approximate value for the overturning moment can be found by calling p 1 the 
piessure per lineal foot of span concentrated upon the upper lateral systeiu, then 
J) f d =r ?r 4 b 
and ir 4 =~y 
■fhe latter value of is not so exact as. the former, but is much more easily 
calculated. 
The transferred panel load ib^of course equal to tr 4 /, and the reduced panel 
oad Tr 6 = TF! — 了 F 4 = % - «. 4 /• 
The following table gives approximate values for tc 4 for tlie single track through 
biulgcs of this treatise 
Span 
W\ 
Span 
«.4 
Span 
W4 
7 び 
160 
16c/ 
290 
220f 
440 
8 〇， 
180 
i 7 c f S. I. 
300 
230 ， 
460 
gc f 
210 
170, D. I. 
340 
240 ， 
480 
ioo f 
<230 
18c/ S. T 
520 
2 $C f 
500 
IIO' 
240 
1 8c' D.I. 
560 
26o f 
520 
I20 f 
250 
19 。， S. I. 
340 
TJC ， 
540 
1 3 ヴ 
260 
19c ， D.I. 
580 
2 さ 。' 
560 
】 4 。， 
270 
200^ 
400 
29 。， 
580 
i go ， 
a8o 
210' 
420 . 
30 o' 
600 
Tlie value of tr 5 , the transferred load per lineal foot of span, may be calculated 
a s follows. 
• Tlie wind pressure of 240 pounds per lineal foot acts with a leverage of about 
feet, producing an overturniug moment of 9 x 210 = 1920 foot pounds. If in 
the equation 
U，4 
p f d 
ぐ 'e substitute ir 5 for w 4 and (tlio pressure per lineal foot of spau upon the upper 
a era l s y ß tem, when tlie wind pressure is thirty pounds per square foot) for 〆， and 
ac W 1920 foot pounds to the moment, we will have 
n ' 6 : 
p"d + 1920 
From this equation lias been prepared the following table. 
