40 STANDARD SPECIFICATIONS 



163. Compression Flange. The gross section of the compres- 

 sion flange shall not be less than the gross section of the tension 

 flange. The unsupported length of the flange shall generally 

 not exceed 16 times its width in buildings, or 12 times its width 

 in bridges. 



Where the unsupported length exceeds these ratios the flange 

 shall be considered as a column between the points of sup- 

 port. 



The compression flanges of girders without cover plates shall, 

 in buildings, have a minimum thickness of one-sixteenth (^) 

 of the width of the outstanding leg, and in bridges a minimum 

 thickness of one-twelfth (^). 



In bridges, where cover plates are used, one plate of the 

 top flange shall extend the whole length of the girder. 

 In through bridges this plate, or a plate of the same width, 

 shall be extended over the rounded corners and be continued 

 down, either below the corners of the adjacent girders, or 

 at the extreme ends of the bridges down to the bottom of the 

 girder. (Par. 157.) 



164. Flange Rivets. The flanges of plate girders shall be 

 connected to the web with a sufficient number of rivets to trans- 

 fer the calculated shear at any point, in a distance equal to the 

 distance between centers of gravity of rivet lines at that point, 

 combined with any load that is applied directly on the 

 flange. 



The wheel loads, where rails rest directly on the flange, shall 

 be assumed to be distributed over 30 in.; where the ties rest on 

 the flanges the wheel loads shall be assumed to be distributed over 

 three ties. (Pars. 171, 283.) 



165. Design of Web. The web shall be designed for the^otal 

 maximum shear, assuming this to be uniformly distributed over 

 its gross area. 



The thickness of web plates shall not be less than one one- 

 hundred and sixtieth ( T |-0-) of the unsupported distance between 

 flange angles. 



1 66. Web Splices. When necessary to splice, the web the 

 splice plates and the number of rivets shall be sufficient to resist 

 the maximum stresses resulting from a combination of bending 

 and shear at that point. (Par. 171.) 



167. Web Stiffeners. Web stiffeners shall be located in pairs 



