220 STEEL RAILWAY BRIDGES. CHAP. IV. 



(8) Where distance between adjacent surfaces is f in. or more, filler rings shall be provided 

 to prevent lateral motion, but the aggregate length of such filler rings shall be , in. less than the 

 neat length required, after making necessary allowances for packing. 



(9) The neat grip of pins shall be the distance out to out of outside surfaces after making 

 allowances for clearance. 



(10) The ordered length of pins between shoulders shall exceed the neat grip by the following 



allowances: 



For pins of 3^ in. diam. or less, allow j in. 



For pins of 3! in. diam. to 6 in. diam., allow | iiv 



For pins of 6| in. diam. to 91 in. diam., allow f in. 



GIRDER WEBS. Width of Web Plates. On deck girders the web must usually project 

 f in. above the back of the top flange angles, to receive the notches in the track ties, except for 

 concrete deck floors where the slabs rest on a top cover plate. In other cases, where no cover 

 plates are required, the web must be flush with the top flange angles. At the bottom flange in 

 all cases, and at the top flange where cover plates are required, the web may be set back i in. 



Web plates shall not be ordered in widths having a fraction of an inch less than in. 



Thickness. Web plates should have a minimum thickness of ^ in. At web splices \ in. 

 clearance between ends of web plates shall be allowed. 



Web Splices Location. Web splices for girders, when required, should preferably be placed 

 near the third or quarter points, and never when avoidable at the point of maximum moment. 



Size. Web splices should be of sufficient width to take two lines of rivets through each 

 section of the web spliced. When not under floorbeam connection angles, f in. clearance may be 

 allowed top and bottom. 



Moment Splices. In addition there should be splice plates on the vertical legs of the flange 

 angles, designed to splice the portion of the web covered by the flange and where thus spliced, the 

 resisting moment on the web may be taken as equivalent to that of | of its gross area considered 

 as flange section. 



Where the splice plates on the flange angles are omitted, the rivets in the flange angles for a 

 distance of one foot either side of the splice may be considered as part of the group of splicing rivets, 

 and account shall be taken of the longitudinal shearing stress on these rivets as well as the stress 

 due to the splice. 



Riveting. The riveting shall, where practicable, be such as to develop the full strength of 

 the web, and shall always be such as to develop the actual moment carried by the web at any point; 

 this being determined by multiplying the total moment on the section by the ratio of | of the gross 

 web section to the total flange area, including this web equivalent. Splices shall also be designed 

 to carry the total shear on the section due to the assumed loading. 



GIRDER FLANGES. i. Composition. At least of the area of the flange section should 

 consist of angles, or else the maximum size of the latter be used, and in no case should the center 

 of gravity of the flange come above the flange angles. For location of center of gravity for various 

 types of flange and sizes of material, see Table 88, Part II. 



2. Composition of flanges shall preferably be as follows: 



(1) 6" X 6" angles without cover plates. 



(2) 6" X 6" angles with 14 in. or 16 in. cover plates. 



(3) 8" X 8" angles with 17 in. or 18 in. cover plates. 



(4) 8" X 8" angles with 2 or 4-6" X 4" angles, without cover plates. (Type A4.) 

 Thickness of flanges without cover plates shall not be less than T V the width of the outstanding 



leg of the angle. 



3. Net Section. The riveting in the tension flanges shall be computed according to method 

 shown in Tables 109 to 113, Part II. Where the spacing of flange rivets is not known in advance, 

 about the following allowances shall be made. In detailing flange riveting, where there is not a 

 considerable excess of flange section, endeavor to keep within these allowances: 



(1) Flange angles without cover plates and without lateral bracing connections, each angle 

 one hole out. 



(2) Flange angles without cover plates, but with lateral connections, each angle if holes 

 out. 



(3) Flange angles with cover plates, each angle two holes out. 



(4) Cover plates two holes out. 



4. Cover Plates. Cover plates shall have the same thickness or shall diminish in thickness 

 from the flange angle out. In determining length of cover plates, the curve of maximum moments 

 shall be established and plates shall be made I ft. longer at each end than the theoretical require- 

 ment. 



5. Flange Splices. Flanges shall never be spliced unless it is impossible to get material of 

 the required length. Where flange splices occur the following requirements shall be observed: 



