—— 102 — 
Span 
Span 
w 5 
70 r 
240 
160' 
300 
So r 
250 
1 70 f S. I. 
3.0 
9 ヴ 
260 
170 ' D. I. 
350 
ioo f 
270 
180^ S. I. 
3-20 
IIC^ 
275 
180» D. I. 
340 
!2C f 
*280 
1 90^ S. I. 
330 
リヴ 
285 
19^ B. I. 
350 
I4C/ 
290 
370 
I50 ， 
295 
2IC f 
390 
It limy bo noticed that these values of do not agree exactly iu all cases with 
those used in preparing the diagrams of stresses which accompany this treatise. 
Both values are merely approximate, but those in the table are preferable. 
Tlie teason for the disagreement is that the area per lineal foot of span opposed 
to tlic wind lind fiisfc to bo n/ssiuiiotl (inti fiftor weirds cliGckcd. As tliG clisftgi'CGiiiciit 
varies from zero to only seven per cent of the transferred load, aiid as the latter is 
but it small poi tioii of tlie to till lon.fl, it is not \\^>rtli wliilc to correct the dingrcims of 
stresses. 
Tlie formulae for the stresses due to 1V 5 and W ß are identical with those for 
Jl ’!： they can either bo obtained from the previous part of this chapter, or from one 
of Tables III and IV. 
To calculate the values of ]V 1 and 
let v = maximum velocity of train iu feet per second 
g = acceleration of gravity 
r = radius of tlie curve 
W 
W=1 1 
, W 7 
and ?r 7 = 了 : 
: live load per foot of span 
centrifugal force per lineal foot due to car load 
then u 、 
w ? ,2 
ff’ r 
For sixty miles per hour v 
iv (88) 2 
マ t，7 : 
3 2. 2 r 
88 ; and 〇 = 32.2, therefore 
240 ~ . 
from wliicli it is evident that, in order to make tlie centrifugal force Lave the same 
effect as the live load, the radius of tlie curve must be 210 feet. Generally it is not 
much less tliaii 1 ，〇 00 feet, consequently the ceiitrifugal force seldom produces stres- 
se& one fourth as great as those clue to the live load. In ci similar maimer we cau 
establish the equation 
= 240 — 
The formulae for the stresses due to JV 7 are identical with those clue to W n and 
TF 3 . . 
The formula for the concave side chord stresses due to E v w)icn tlic panel length 
is not less than eighteen feet is 
5 000005050 
w 14780 I?) 46 
4 4 4 4 5 5 5 5 5 
SI 
CCOOGOOC — 
2 2 J 4 56 700 9 c 
220* 2 22 2 23 
