Nickel Steel 



Net Section 

 at Rivet Holes 



Net Section 

 at Pin Holes 



Limiting 

 Lengths of 

 Members 



Open 

 Sections 



Water 

 Pockets 



Symmetrical 

 Sections 



Minimum 

 Material 



Outstanding 

 Flanges 



Douglas fir and Southern long-leaf pine Perpendicular to grain . 



Across grain 



White and red pine and Spruce Perpendicular to grain 



Across grain 



Granite masonry 



Concrete 



Limestone masonry 



Sandstone masonry 



1000 

 300 

 700 

 170 

 800 

 600 

 400 

 400 



51. The above mentioned values for shear and bearing shall be reduced 25 per cent, 

 for countersunk and floor connection rivets. 



52. The diagonal tension in webs of girders or rolled beams at sections where shear 

 and bending occur simultaneously, shall not exceed 16 000 pounds per square inch. 



53. When "Structural Nickel Steel" is used, the Unit Stresses for this material 

 may be 40 per cent, in excess of those given above for "Structural Steel for Bridges." 



PROPORTIONING OF PARTS 



54. In proportioning riveted tension members, the diameter of the rivet holes shall 

 be taken 1/8 inch larger than the nominal diameter of the rivet; and allowance shall be 

 made in each component part of the member for as many rivet holes as it contains gauge 

 lines, unless the distance centre to centre of rivet holes, measured on the diagonal, is at 

 least 40 per cent, greater than the distance between the gauge lines. 



55. In pin connected riveted tension members, the net section, both through the 

 pin hole and at the back of same, shall exceed the net section of the body of the member 

 by at least 25 per cent. 



56. The ratio of length to least radius of gyration shall not exceed 100 for main 

 compression members nor 120 for wind and sway bracing, but for built up I sections the 

 radius of gyration may be computed for the flange materials alone, neglecting the web 

 plate, in which case the latter shall not be counted on as effective section for axial com- 

 pression. 



57. The lengths of riveted tension members shall not exceed 200 times their least 

 radius of gyration. 



58. Structures shall be so designed that all parts will be accessible for inspection, 

 cleaning and painting. 



59. Pockets or depressions shall be avoided as far as possible, and those which are 

 unavoidable shall either be provided with effective drain holes, or they shall be filled 

 with waterproof material, as directed by the Engineer. 



60A. Main members shall be so designed that their neutral axes will be as nearly 

 as practicable in the centres of their sections, and the neutral axes of all intersecting mem- 

 bers shall meet in a common point. 



61. Metal shall not be less than 3/8 inch thick, except for fillers. Metal subject 

 to marked corrosive influences shall be increased in thickness or protected against 

 such influences, as specified by the Engineer. 



62. No material used in compression shall have an unsupported width of more than 

 40 times its thickness. 



63. The thickness of the outstanding leg of angles in compression, except when rein- 

 forced by plates, shall not be less than the following: 



(a) For girder flange angles, or for main members carrying axial stress, 1/12 



the unsupported length of the outstanding leg. 



(b) For bracing, stiffeners, and other secondary members, 1/16 the unsupported 

 length of the outstanding leg. 



