WEIGHTS OF STEEL HIGHWAY BRIDGES. 112a 



2. Steel Low Truss Spans, with Stringers. For low truss highway bridges with spans of 

 ft. to s.s ft., not including the weight of the fence or the steel stringers, the weight of structural 



T liiir.il foot of span for a i6-ft. roadway is 



W = 235 + 2.35^- (8) 



ami tor .in l8-ft. roadway is 



W = 240 -f 2.40!,. (9) 



3. Steel Low Truss Spans, without Stringers. For low truss highway bridges with spans of 

 35 ft. to 100 ft., not including the weight of the fence or steel floorbeams, the weight of the struc- 

 tural steel per lineal foot of span for a i6-ft. roadway is 



W = 200 -f 4,L. (10) 



for an i8-ft. roadway is 



W = 225 + 4.25 L. (u) 



4. Steel High Truss Spans, with Stringers. For high through truss highway bridges with 

 ins of from 90 ft. to 150 ft., not including the weight of fence or the steel stringers, the weight of 



structural steel per lineal foot of span for a i6-ft. roadway is 



W = 245 + 2.45!,. (12) 



for an i8-ft. roadway is 



W = 270 + 2.7 L. (13) 



WISCONSIN HIGHWAY COMMISSION. Steel highway bridges with reinforced con- 

 te floor. Reinforced concrete floor slabs 6 in. thick for all spans. Live loads for the floor and 

 supports a 1 5-ton road roller with two-thirds of the load on the rear axle, axles 10 ft. centers, 

 rolls 4 ft. 10 in. centers, rear rolls 20 in. wide. The trusses designed for the loads given in 

 Table I. No allowance is made for impact. Let W = weight of structural steel in Ib. per lineal 

 : of span, L = length of span in feet; b = width of roadway in feet (without sidewalks). 



1. Steel Beam Spans. Weight of steel beam spans from 10 ft. to 38 ft. and for i6-ft., l8-ft. 

 2o-ft. roadway are given in Table X. 



2. Steel Through Plate Girders. The weight of the structural steel in through plate girder 

 iway bridges from 35 ft. span to 80 ft. span including floorbeams spaced 3 to 2\ ft. apart, is 

 sn approximately by the following formula. For a i6-ft. roadway 



W = 300 + ZL. (14) 



an i8-ft. roadway 



W = 300 + 3-25- (15) 



for a 2O-ft. roadway 



W = 320 + *L. (16) 



3. Steel Low Truss Spans, with Stringers. The weight of the structural steel in low truss 

 el highway bridges with spans of 35 ft. to 85 ft. span, not including 1 the weight of the fence or 

 : steel stringers, is given approximately by the formula. For a i6-ft. roadway 



W = 80+3.5!,. (17) 



and for an l8-ft. roadway 



W = 80 + *L. (18) 



4. Steel High Truss Spans, with Stringers. For high through truss steel highway bridges 

 with spans of from 90 ft. to 150 ft., not including the weight of the fence or the steel joists, the 

 weight of structural steel per lineal foot of span is given approximately by the formula. For a 

 i6-ft. roadway 



W = 180 + 2L. (i g ) 



and for an i8-ft. roadway 



W = 240 + 2L. ( 20 ) 





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