34 STANDARD SPECIFICATIONS 



Forked ends on compression members will be permitted only 

 where unavoidable; where used a sufficient number of pin plates 

 shall be provided to make the jaws of twice the sectional area 

 of the main member. At least one of these plates shall extend 

 to the far edge of the farthest tie-plate and the remainder not 

 less than 6 in. beyond the near edge of the same plate. 



144. Tie-plates. The open sides of compression members 

 shall be stayed by diagonal lattice having tie-plates as near 

 each end as practicable and at intermediate points where the 

 lattice is interrupted. In main members the end tie-plates 

 shall have a length not less than the distance between the lines 

 of rivets connecting them to the flanges, and intermediate tie- 

 plates not less than one-half (J) this distance. Their thickness 

 shall not be less than one-forty-eighth (fa) of the same distance. 



145. Lattice Bars. Single lattice bars shall have an inclina- 

 tion of approximately 60 degrees with the axis of the main mem- 

 ber and shall have minimum thickness of one-fortieth (fa) of 

 the distance between the rivets connecting them to the member. 

 Single lattice bars may be connected with one rivet, except in 

 flanges more than 5 in. wide, where two rivets shall be used. 



Double lattice bars shall be used where the distance between 

 rivet lines in the flanges exceeds 15 in. They shall have a 

 minimum thickness of one-sixtieth (^) of the distance between 

 the rivets connecting them to the member, shall have an inclina- 

 tion of approximately 45 degrees, and shall be riveted at their 

 intersection. 



Lattice bars shall be so spaced that the portion of the flange 

 included between their connection shall be as strong as the 

 member as a whole. 



Instead of lattice bars shapes of equivalent strength may be 

 used and where angles are used they shall be connected by at 

 least two rivets. 



The minimum width of lattice shall be: 2J in. for |-in. rivets, 

 2J in. for f-in. rivets and 2 in. for J-in. rivets 



The latticing of compression members shall be proportioned 

 to resist the shearing stresses corresponding to the allowance for 

 flexure for uniform loading provided in the column formula (Par. 

 1.17c) by the term 70 l/r. 



146. Pins. The minimum diameter of pins shall be eight- 

 tenths ( T \) of the width of the widest eye-bar attached thereto. 



