CHAPTER III 

 Problems in Design of Beams 



THE two standard steel handbooks are the " Carnegie Pocket 

 Companion " and the " Cambria Steel Manual." The 

 designer should have one "or both of these books. The 

 Bethlehem Steel Company issues a handbook which the designer 

 should also possess, owing to the differences in shape and carrying 

 capacity of the Bethlehem and standard beams. 



The Cambria and Carnegie handbooks contain a great deal of 

 text book matter and are very useful to students and to men who 

 wish occasionally to refresh their memories on points of design. 

 They contain the usual tables indispensable to structural de- 

 signers. The handbook of the Lackawanna Steel Company and 

 that issued by Jones & Laughlin contain the indispensable tables 

 and some memory aiding text, but not as much as the first books 

 mentioned. 



For a uniformly distributed load the size of a beam is easily 

 obtained. Tables give the uniformly distributed loads in pounds 

 for all spans, varying by v single feet which the different beams can 

 carry. By reducing concentrated loads to their equivalents in 

 uniformly distributed, loads these tables may be used for any 

 system of loading without first ascertaining the bending moment. 



When concentrated loads are dealt with as such and the bend- 

 ing moments are found, the proper size beam may be found by 

 looking up the bending moment in foot pounds, opposite which, 

 on the same line, is found the size and weight of the beam. Beams 

 must be secured (stayed) laterally to prevent side bending ; other- 

 wise the carrying capacity is less than that given in the tables. 



The Carnegie book formerly gave a factor of strength, C, to 

 use when the bending moment was used. It is designated as C 

 in the Bethlehem book and as F in the Cambria book. In the 1913 

 edition of Carnegie this factor is not given, the bending moment 

 in foot pounds being shown on the page containing the other 

 properties of beams. 



