i8o 



FRAMEWORK 



82, and is commonly used for simple mill buildings. Extensions can 

 be made with about equal ease in either case, and the choice of methods 

 will usually be determined by the local conditions of the problem and 



FIG. 82. A. T. & S. F. R. R. BLACKSMITH SHOP, TOPEKA, KAS. 



the fancy of the designer. In train sheds and similar structures the 

 end trussed bent (b), Fig. i, is used. Where the truss span is quite 

 long, as in train sheds, the end trusses are often designed for lighter 

 loads than are the intermediate trusses, thus saving considerable ma- 

 terial. In the case of simple mill buildings of moderate size all trusses 

 are, however, commonly made alike, the extra cost of detailing being 

 usually more than the amount saved in material. 



In train sheds, coliseums, and similar structures requiring a large 

 floor space, the three-hinged arch is very often used in place of the 

 typical transverse bent system. 



The various parts of the framework of mill buildings will be taken 

 up and discussed in order. 



TRUSSES. Types of Trusses. The proper type of roof truss 

 to use in any particular case will depend upon the span, clear headroom, 

 style of truss preferred, and other conditions. For spans up to about 

 100 feet, the Fink type of truss is commonly used. This type of truss 

 has the advantage of short struts, simplicity of details and economy. 

 The stresses that control the design are with but a very few exceptions 



