Bracing of 

 Stringers 



Gusset Plates 

 in Through 

 Girders 



Rocker 

 Bents 



Depth of 

 Girders 



Girder 

 Connections 

 and Bracing 



Bottom 

 Struts 



Shoe and 

 Bed Plates 

 Anchorage 

 for Towers 



Packing of 

 Eye Bars 



Pin Plates 



11 



89. Where two lines of stringers are used under each track, in panels more than 15 

 feet in length, they shall be subdivided into two or more panels and braced diagonally, 

 and shall have a brace frame at each panel point. 



90. In through plate girder spans, the top flanges shall be braced by means of gus- 

 set plates or knee braces with solid webs connected to the floor beams and extending 

 usually to the clearance line. If the unsupported length of the inclined edge of the 

 gusset plate exceeds 60 times its thickness, the gusset plate shall have one or two stiffen- 

 ing angles riveted along its edge. The gusset plate shall be riveted to a stiffener angle 

 on the girder. Preferably it shall form no part of the floor beam web. 



91. In through plate girder spans with solid floors, there shall be knee braces with 

 Y* inch webs, extending usually to the clearance line at intervals of about 12 feet. Each 

 knee brace shall be well riveted to the floor and the girder, especially at the top, and 

 shall have its edge reinforced by one or two angles. 



PROPORTIONING OF PARTS (VIADUCTS) 



92. Where long spans are supported on short single bents, such bents shall have 

 hinged ends, or else have their columns and anchorages proportioned to resist the bend- 

 ing stresses produced by changes in temperature. 



93. Preferably all the girders in any one viaduct shall be of the same depth. 



94. In double track viaducts the inner lines of girders shall be supported by trans- 

 verse girders framed between and riveted to the posts. 



95. Girders of tower spans shall be fastened at each end to the tops of the posts or 

 transverse girders. Girders between towers shall have one end riveted, and shall be 

 provided with an effective expansion joint at the other end. No bracing or brace frame 

 shall be common to abutting spans. 



96. If either of the girders under a track does not rest directly over a tower post 

 bracing shall be provided to carry the longitudinal force into the tower bracing without 

 producing lateral bending stress in the transverse girders or the posts. 



97. The bottom struts of viaduct towers shall be proportioned for the calculated 

 stresses, but in no case for less than one-fourth of the dead load reaction on one pedestal, 

 considered as compressive stress. Provision shall be made in the column bearings for 

 expansion of the tower bracing. 



98. Shoe and bed plates shall be not less than 1J^ inches thick. 



99. Anchor bolts for viaduct towers and similar structures shall be not less than 

 2 inches in diameter. They shall be designed to engage a mass of masonry the weight 

 of which is at least one and one-half times the uplift. 



DETAILS OF DESIGN 



100. The eye bars of a set shall be packed symmetrically about the plane of the 

 truss as closely and as nearly parallel as practicable, and in no case shall the inclination 

 of any bar to the plane of the truss exceed 1/16 inch per foot. They shall be held against 

 lateral movement and arranged so that adjacent bars in the same panel will not be in 

 contact. 



101. Pin plates shall be of sufficient thickness to provide the required bearing area 

 upon the pin; they shall be as wide as the dimensions of the member will allow; and 

 their length measured from pin centre to end, shall be at least equal to their width. 

 Pin plates shall contain sufficient rivets to distribute their due proportion of the pin- 

 pressure to the full cross section of the member; and only the rivets located in front of 

 two lines drawn from the centre of the pin towards the body of the member and inclined 

 at 45 degrees to the axis of the member shall be considered effective for this purpose. 

 In the case of members composed of web plates and flange angles (with or without a 

 cover plate) there shall be at least one outside pin plate covering the vertical legs of the 

 flange angles. 



