270 



STRESSES IN A CAMEL-BACK TRUSS. Art. 137. 



1000 



=0.3. 



Live load = 1600 Ibs. per foot of bridge, 



Dead load panel load =i X 1000 X20 = 10,000 Ibs. 



Live load panel load =J X 1600 X20 = 16,000 Ibs. 



The chords receive their maximum stresses under full load 

 (128). 



Center of moments at 8, 



18L!=20fli=3PX20. 



LI =L 2 =3 X 10,000 Xff =33,330 Ibs. (-) D. L. 

 =3 X 16,000 X ft =53,330 Ibs. (-) L. L. 



86,660 Ibs. (-) Total. 

 Center of moments at 9. 



24L 3 =40# 1 -20P=3PX40-PX20 = 

 100X10,000 



L,= 



24 



= 41,600 Ibs. (-) D.L. 



100X16,000 .. ___ lu , ^ T T 

 - = 66,670 Ibs. (-) L. L. 



108,330 Ibs. (-) Total. 

 Center of moments at 10, 



28L 4 =60#! - (20 +40)P = 120P. 

 j _ 120X10, OOP 

 4 ~ 28 

 ^120X16,000 

 28 



= 68,570 Ibs. (-)L.L. 



111,430 Ibs. (-) Total. 



For the top chords the lever arms must be calculated 

 This may be done by similar triangles, thus, 

 Center of moments at 5> 



Arm of f/ 2 24 



-. Arm of U 2 =23.0 ft. 

 20 Length of U 2 



23t/ 2 =40#i-20P = 100P. 

 U 2 = _ ! = 43,480 Ibs. (+) D.L. 



23 



= iooxw)oo = 69;560 Jbs (+) L>L _ 



23 



113,040 Ibs. (+) Total. 



