108 



STEEL HIGHWAY BRIDGES. 



CHAP. III. 



angles to the center line the bridge is called a "skew" bridge. Short span highway and railway 

 bridges have low trusses and no top lateral system nor portals, as in Fig. 2. In a railway bridge 

 the loads are carried to the panel points by stringers resting on or riveted to the floorbeams. 



V 



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Plate Beam Hang*r End View 



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 4*6 felloe Guard 

 II I U I I I I I I I | I ' ' 

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Quarter lop Plan 



Quarter Bottom Plan. 



*-- -Floor beam 

 Cross Section 

 FIG. 2. PLAN OF A Low OR "PONY" TRUSS HIGHWAY BRIDGE. 



The simplest type of bridge is the beam bridge, (a) Fig. 3. Beam bridges commonly consist 

 of I beams which span the opening, and are placed near enough together to carry the floor of the 



(a) B>eam Bridge. 



(a/) L ow Warren Truss. 



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I 



(b) Beam L eg Bridge, (e) Low Pratt Truss. Half Hip. 



(c) Truss L eg Bridge. (f) L ow Pratt Truss. Full 5 I ope. 



FIG. 3. TYPES OF SHORT SPAN HIGHWAY BRIDGES. 



bridge. Where foundations are relatively expensive the beams may be carried on posts as in 

 (b), Fig. 3. A truss leg-bridge is shown in (c), Fig. 3. Types (b) and (c) unless constructed with 

 great care make inferior structures and are not to be recommended. A Warren truss is a combi- 



