TRANSVERSE BENTS. 



'95 



usually control the spacing of the trusses so that it is not necessary that 

 we know the economic spacing very definitely. 



For long spans the economic spacing can be increased by using 

 rafters supported on heavy purlins, placed at greater distances than 

 would be required if the roof were carried directly by the purlins. This 

 method is frequently used in the design of train sheds and roofs of 

 buildings where plank sheathing is used to support slate or tile cover- 

 ings, or where the tiles are supported by angle sub-purlins spaced close 

 together as shown in Fig. 87. 



TRANSVERSE BENTS. The proper cross-section for a mill 

 building will depend upon the use to which the finished structure is to 



Gravel Roof- 



Skylight 



- 73-0" 



_-* $ 9 '-9 



i 



Q> "TYusses Spaced 18 0* 



/ V-'Concrete'V \ 



rFF tftr? 



4iw 



I * 



If 



.t.i.r 



'50-0' 



400' Long 

 Locomotive Shop- Oregon Short [line 



FIG. 89. 



be put. A number of the common types of transverse bents are shown 

 in Fig. 88. Transverse bents (a), (b), (d) and (h) are commonly 

 used for boiler houses, shops and small train sheds. Where a travel- 

 ing crane is desired, the crane girders are commonly suspended from the 

 trusses in the bents referred to, although the crane may be made to 

 span the entire building as in (h). Transverse bent (d) was used 

 for a round house with excellent results. Transverse bents (f) and (g) 

 are quite commonly used where it is desired that the main part of the 

 building be open and be provided with a traveling crane that will sweep 



