All posts of i 



deck bridges />== 9,000 40 for live load, 

 and trestles. 



,000 80 for dead load. 



End posts are not to be considered chord segments. 



Lateral struts ^ 



and rigid P= 13,000 60 

 bracing. 



for lateral forces ( 24, 25); 

 for live load strains use two-thirds of the 

 above ( 27, 29, 109). 



/ > =the allowed strain in compression per square inch of 

 cross-section, in pounds. 



/=the length of compression member, in inches, c. to c., 

 of connections. 



r=the least radius of gyration of the section, in inches. 



No compression member, however, shall have a length Limitation of 

 exceeding 100 times its least radius of gyration for main wJ! 

 members, or 120 times for laterals. The least width of posts Mem^s" 01 

 will be 10 inches. 



For swing bridges and other movable structures, the 

 dead load unit strains during motion must not exceed J of 

 the above allowed unit strains for dead load on stationary 

 structures. 



36. Low Steel ( 144) may be used in compression with Lowsti. 

 unit strains ten per cent, less than those allowed for Medium 

 Steel. (138.) 



37. For long span bridges, when the ratio of the length 

 and width of span is such that it makes the top chords, act- 

 ing as a whole, a longer column than the segments of the 

 chord, the chord will be proportioned for this greater 

 length. 



38. All members and their connections subject to alter- AU 



St rai-tx 



nate strains of tension and compression shall be proper- 



