208 



TYPES OF ROOF TKt'SSKS. 



Art. 118. 



the same type and pitch by simply multiplying them by the 

 panel load. Such tables will be found in many structural 

 handbooks. 



FINK TRUSS 



fa) 



TRIANGULAR TRUSS 



(b) 



FAN TRUSS 

 (O 



HOWE TRUSS 



PRATT TRUSS 



(dj 



FINK TRUSS 



(fj 



FAN TRUSS 



(9J 



QUADRANGULAR TRUSS 



TRIANGULAR TRUSS 

 (U 



Fig. 149. 



A few of the more unusual types of roof trusses are shown 

 in Fig. 150. Three-hinged arches are frequently used for expo- 

 sition buildings, auditoriums, drill halls, etc., where it is de- 

 sirable to have a large floor space unobstructed by columns. 

 The scissors truss is used for buildings with steep roofs where 

 the trusses are exposed on the interior, such as churches. Here 

 the trusses are usually made of timber except the vertical rod 

 in the middle. The cantilever trusses arc used for grand stand 

 roofs and sometimes for freight houses where the cantilever 

 portion covers the loading platform. 



The saw-tooth roof was invented especially .for the weaving 



