358 QUESTIONS AND PROBLEMS. CHAPTER XIV. 



1. If a tension chord stress due to vertical loads is 240,000 

 Ibs., and the wind stress in the same chord member is 72,000 

 Ibs., what unit stress must be used in determining the cross 

 section according to the Specifications for Steel Railroad Bridges 

 of the Am. Ry. Engineering Assoc. (4th Edition, see Sees. 

 15 and 25) . 



2. The bridge shown in Fig. 204 has a span of 120 ft., 

 height 25 ft., distance cent, to cent, of trusses, 16 ft. The end 

 post stresses are, Dead Load =94,000 Ibs., Live Load = 196, 000 

 Ibs. ^ = 14 inches. & 2 = 15 inches. The end posts are alike. 

 7=8 ft. Wind Load = 150 Ibs. per lin. ft. of top chord. Are 

 the end posts fixed at either end? Find the stresses in the 

 portal bracing if it is of the type shown in Fig. 217. 



Find the maximum stress per sq. in. in the End Posts if 

 7=1,790, and the maximum width of the member is 21 inches. 



3. Find the percentages of the load which will go to the 

 stringers of the second panel of Fig. 226. 



4. Find the percentages of load which will go to the hip 

 verticals of Fig. 226. 



5. Show why the maximum bottom chord stresses of the 

 two trusses of a through bridge on a curve will not be equal, 

 when the track is so placed that the maximum stresses in the 

 top chords are equal. 



