CHAPTER XVIIL 
COMPLETE DESIGN FOR A BRIDGE. 
卜％】 的 山 6 bridge to l>e designed be ft through bridge of one span for a single straight 
^an(l l e “h e l eil gth of span be 108 feet from centre to centre of end chord pins. 
Co Chapter VI. we find the live load to be 1150 pounds per lineal foot. 
2 . ing Table I. we see that there should be eight panels, making the panel length 
uia 6 ド’ that 山 6 depth of truss should be 25 feot, and that the probable dead load 
^ 6 ^ S8ume d as 1480 pounds per lineal foot.* 
toils U VII. we find tlie engine excess for one panel of one truss to be 1().7 
Chapter \丄 gi ves the clear roadway about 13.7 feet, aiul by consulting the 
be 2 Q amS 0U ^ a ^ es XXVI. and XXVII. we find the probable wicUli of choril plate to 
15 4 f 1UC h es or 】.7 feet, making the width of bridge between central planes of trusses 
e ^Df^ 10111 VII. we fiatl the wind pressures per lineal foot when the bridge is 
the ° a 】) ou t 180 pounds for tlie upper lateral system and say 310 pounds foi* 
low 0 『 ei hteral system ; also 240 -J- 200 = 440 pounds per lineal foot for the 
an “ ay 120poumls for the upper lateral system when the 
f 10n：l Chapter VIII. we find Uie approximate valae of to be 300 pounds, and 
认 at of 
'810 pou nt i s 
The ta «gent of the inclination 
rpi 一 
tlia j- 001 responding secant (vide Table II) is about 1.80 6, making tlie length 
^«gonal 25 x 1.300 = 82.05 feet. 
p ie tanReut ^ 0l * the lateral systems is — = 1.3G1. 
1X1 山 6 preceding data we can fill out the following list. 
of a diagonal to the vertical is 
0.84. 
of 
：8_ 
21 
w . 
n ' 
^ sec 6 : 
0.7548 
0.9858 
re asou f or n ^ ，ftVe h <leu better to fissume the dead load to be 1487 pounds per liueal foot. The 
The different ms <lone so is t)iat this chapter was written before Table I was quite finished, 
dng less than four ppr cent is of no importance. 
