PART IV 



PLATE GIRDERS 



153. General Requirements. (See Pars. 49-58 and 105-108.) 



154. Loading. The loading upon plate girders shall be 

 taken, when used in 



Buildings, from Pars. 1, 2 and 8-11; 

 Highway bridges, from Pars. 59-64; and 

 Railroad bridges, from Pars. 109-116. 



155. Unit Stresses. All parts of plate girders, or plate-girder 

 bridges, shall be so proportioned that the sum of the maximum 

 stresses shall not exceed for structural steel and rivet steel the 

 following values in pounds per square inch, except as modified 

 in Par. 124. 



(a) Axial tension, net section 16,000 Ibs. 



<6) Bending, net section of tension flange (Par. 163) . . . 16,000 " 



Pins, on extreme fibers 24,000 " 



(c) Axial compression, gross section, 



S = 16,000 -70-, 



where S= allowable unit stress, 



Z=unsupported length of member in inches (Par. 167), 



r least radius of gyration of member in inches. (Pars. 



39, 96 and 143.) 

 (d) Shear on: Turned bolts and field rivets, when hand 



driven 9,000 Ibs. 



Field rivets, when power driven 11,000 " 



Shop-driven rivets and pins 12,000 " 



Webs of girder, gross section 10,000 " 



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