204 FRAMEWORK 



Columns made of two channels laced, or two channels and two 

 plates, are used where moderately heavy loads are to be carried. Chan- 

 nel column (a), with channels turned back to back and laced, is the form 

 most commonly used; column (b), with the backs of the channels 

 turned out and laced, gives a better chance to make connections and can 

 be made to enter an opening without chipping the legs of the channel ; 

 column (c) is a closed section and is seldom used on that account. The 

 cost of the shop work on column (b) was formerly considerably more 

 than for column (a), for the reason that it was impossible to use a 

 power riveter for driving all the rivets. A pneumatic riveter is now 

 made, however, that will drive all the rivets in column (b), and the 

 shop cost for columns (a) and (b) are practically the same. 



Where very heavy loads are to be carried, columns (d) or (e) are 

 often used. Column (d), composed of two channels and one I beam, 

 is a very economical column and is quite often used as a substitute for 

 the Z-bar column shown in (e), for the reason that it can be built up 

 out of the material that is in stock or that can be easily obtained. Con- 

 nections for beams are easily and effectively made with either columns 

 (d) or (e). The special I beam column (j), with flanges equal to the 

 depth of the beam, is now being rolled in Germany by the use of a 

 process patented by an American, Mr. Henry Grey. This column makes 

 an almost ideal column for heavy loads, since it has all the advantages 

 of the Z-bar column with a very much smaller shop cost. The Larimer 

 column (k) is a patented column manufactured by Jones & Laughlins, 

 and is used by their patrons quite extensively. The Gray column (1) 

 is a patented column and is but little used. Columns made of four 

 angles box-laced, are used where extremely light loads are carried by 

 very long columns. The shop cost of column (m) is somewhat less 

 than that of column (n), although with small angles there is no dif- 

 ficulty in riveting (n) with a machine riveter. Column (o) is a very 

 poorly designed column, for the reason that the radius of gyration is 

 very small for the area of a cross-section of the column. Columns 

 made of two angles "starred" and fastened at intervals of two or three 



