SPECIFICATIONS. 143 



2\ in. for |-in. rivets, and 2 in. for |-in. rivets. The maximum pitch in the line of stress for 

 iiienilHTs composed of plates and shapes shall be 16 times the thickness of the thinnest outside 

 pl.ite or 6 in. Fur angles with two gage lines and rivets staggered, the maximum shall be twice 

 the above iii each line. Where two or more plates are used in contact, rivets not more than 12 in. 

 ap.nt in either direction shall be used to hold the plates well together. In tension members com- 

 pnM-d of two angles in contact, a pitch of 12 in. will be allowed for riveting the angles together. 



<>.V Edge Distance. The minimum distance from the center of any rivet hole to a sheared 

 edge shall be I J in. for |-in. rivets, I J in. for j-in. rivets, and i{ in. for f-in. rivets, and to a rolled 

 edge i}, ij and i in., respectively. The maximum distance from any edge shall be eight times 

 the thickness of the plate, but shall not exceed 6 in. 



64. Maximum Diameter. The diameter of the rivets in any angle carrying calculated stress 

 shall not exceed one-quarter the width of the leg in which they are driven. In minor parts j-in. 

 rivets may be used in 3-in. angles, J-in. rivets in 2j-in. angles, and |-in. rivets in 2-in. angles. 



65. Long Rivets. Rivets carrying calculated stress and whose grip exceeds four diameters 

 shall be increased in number at least one per cent for each additional -fa-in. of grip. 



66. Pitch at Ends. The pitch of rivets at the ends of built compression members shall not 

 exceed four diameters of the rivets, for a length equal to one and one-half times the maximum 

 width of member. 



67. Compression Members. In compression members the metal shall be concentrated as 

 much as possible in webs and flanges. The thickness of each web shall be not less than one- 

 thirtieth of the distance between its connections to the flanges. Cover plates shall have a thickness 

 not less than one-fortieth of the distance between rivet lines. 



68. Minimum Angles. Flanges of girders and built members without cover plates shall 

 have a minimum thickness of one-twelfth of the width of the outstanding leg. 



69. Batten Plates. The open sides of all compression members shall be stayed by batten 

 plates at the ends and diagonal lattice-work at intermediate points. The batten plates must be 

 placed as near the ends as practicable, and shall have a length not less than the greatest width of 

 the member or I $ times its least width. 



70. Lattice Bars. The latticing of compression members shall be proportioned to resist 

 the shearing stresses corresponding to the allowance for flexure for uniform load provided in the 

 column formula in paragraph 38 by the term 70 l/r. They must not be less in width than I J in. 

 for members 6 in. in width, ij in. for members 9 in. in width, 2 in. for members 12 in. in width, 

 2j in. for members 15 in. in width, nor 2\ in. for members 18 in. and over in width. Single lattice 

 bars shall have a thickness not less than one-fortieth, or double lattice bars connected by a rivet 

 at the intersection, not less than one-sixtieth of the distance between the rivets connecting them 

 to the members. They shall be inclined at an angle not less than 60 to the axis of the member for 

 single latticing, nor less than 45 for double latticing with riveted intersections. 



71. Spacing of Lattice Bars. 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. The pitch of 

 tlu; lattice bars must not exceed the width of the channel plus nine inches. 



72. Rivets in Flanges. Five-eighths-inch rivets shall be used for latticing flanges less than 

 in. wide; f-in. for flanges from 2^ to 35 in. wide; J-in. rivets shall be used in flanges 3$ in. and 



er, and lattice bars with two rivets shall be used f9r flanges over 5 in. wide. 



73. Splices. In compression members joints with abutting faces planed shall be placed as 

 iear the panel points as possible, and must be spliced on all sides with at least two rows of rivets 



ireach side of the joint. Joints with abutting faces not planed shall be fully spliced. Joints in 

 ;nsion members shall be fully spliced. 



74. Pin Plates. Where necessary, pin-holes shall be reinforced by plates, some of which 

 lust be of the full width of the member, so the allowed pressure on the pins shall not be exceeded, 

 nd so the stresses shall be properly distributed over the full cross-section of the members. These 

 einforcing plates must contain enough rivets to transfer their proportion of the bearing pressure, 



md at least one plate on each side shall extend not less than 6 in. beyond the edge of the nearest 

 itten plate. 



75. Riveted Tension Members. Riveted tension members shall have an effective section 

 through the pin-holes 25 per cent in excess of the net section of the member, and back of the pin 

 at least 75 per cent of the net section through the pin-hole. 



76. Pins. Pins shall be long enough to insure a full bearing of all the parts connected upon 

 the turned body of the pin. The diameter of the pin shall not be less than J of the depth of any 

 eye-bar attached to it.* They shall be secured by chambered Lomas nuts or be provided with 

 washers if solid nuts are used. The screw ends shall be long enough to admit of burring the 

 threads. 



77. Filling Rings. Members packed on pins shall be held against lateral movement. 



78. Bolts. Where members are connected by bolts, the turned body of these bolts shall be 

 long enough to extend through the metal. A washer at least J in. thick shall be used under the 



* The allowable bearing stress = | allowable tensile stress. 





