BETHLEHEM STEEL COMPANY. 



EXPLANATORY NOTES. 



Large additional mill capacity for the manufacture of wide 

 flange structural shapes has made the production of new sec- 

 tions practical where it had been found desirable for the 

 improvement of the previously established line of Bethlehem 

 Structural Shapes. Several new I beam and column sections 

 were recently added, information concerning which has been 

 published. A further desirable improvement has now been 

 made in modifying Bethlehem Girder Beam sections to 

 provide more than one weight of a section. All additional 

 and modified sections to date are shown in this catalogue, 

 together with all previous sections that have not been super- 

 seded. 



Bethlehem Girder Beams. In general three weights are 

 provided for each section, the middleweights corresponding 

 to the previous sections of Bethlehem Girder Beams from G8 

 to G24 a, inclusive. The lighter and heavier weights of each 

 section provide opportunity for greater economy in the selec- 

 tion of sizes for any required purpose. To accomplish this, 

 slight modifications in profile have been made in all girder 

 sections from G8 to G34 a, inclusive. Simplification in the 

 production of the larger girder sections, G26, G28 and G30, 

 has been obtained by changing the profiles to an extent per- 

 mitting all variations in weights of each girder to be pro- 

 cured from the same set of rolls. 



Attention is called to the manner in which the variation in 

 weight of the new girders is obtained by increasing or de- 

 creasing the thickness of the flange as well as that of the web, 

 shown in Fig. 3, instead of obtaining the entire variation in 

 weight bv increasing or decreasing the thickness of the web 

 only. This method was first successfully applied to the three 

 new I beam sections B18 a, B22 and B24 b, and has now been 

 extended to all the girder beams. 



This method of rolling, on which patents are pending, 

 permits obtaining a variation in Section Modulus practically 

 proportional to the variation in weight. Thus G12, 61 Ibs., 

 compared with G12, 55.5 Ibs., has an increase of 7.2 in Section 

 Modulus, or about 10 per cent increase in modulus, due to 

 the increase of 5.5 Ibs. in weight, which is about 10 per cent 

 increase in weight also. The increase or decrease in flange 

 thickness is made at the outside of the flange, thereby slightly 

 varying the depth of the beam; but the total variation in 

 depth from minimum to maximum is not more than the 

 usual allowable tolerance in depth necessary in any method 

 of rolling beams. 



The flanges of all girder beams have a bevel of 8f per 

 cent, or a slope of 1 in 12. 



