Art. 123. 



MODERN BRIDGE TRUSSES. 



225 



In either case the sub-trussing may be of the style shown in 

 Fig. 163 or in Fig. 164, and other members may be introduced 

 cimply to hold the compression members at the middle. 



The two panels at each end are sometimes made as in Fig. 162 

 in order that the end posts may not have such a flat inclination; 

 this makes a combination of Pratt and Baltimore web bracing. 



For short-span highway bridges, the Pratt truss is often 

 modified as shown in Fig. 165. This truss is frequently made 

 with end posts having an inclination of 45 degrees ; when the end 

 panels of the top chord are half as long as the intermediate pan- 

 els, it is called a half-hip truss. 



5 panels @ p=L - 



HALF H/P PRATT 



Fig. 165. 



TRUSS 



Fig. 165 shows a triangular or Warren truss. The use of this 

 style of triangular truss is now confined mostly to small highway 



WARREN OR TRIANGULAR TRUSS 

 Fig. 166. 



bridges with floor beams attached below the bottom chord. For 

 longer spans, the sub-divided Warren truss, as shown in Fig. 167, 

 ia used, and the floor beams are attached to the vertical members 

 above the bottom chord. The suspender evidently carries a single 

 panel load. The other vertical members carry no stress above the 

 floor-beams except that part of the dead load which acts at the 

 upper joints. 



