UNIFORM LIVE LOADS. 



(d) The effective width for shear in beams carrying concentrated loads shall be taken the same 

 as for bending moment as calculated by formula (37) or formula (38), with a minimum effective 

 width of 3 ft. and a maximum effective width of 6 ft. 



Tin- total shear for an effective width of 3 ft. shall be considered as punching (pure) shear. 

 Tin- total slu-ar for an effective width of 4.5 ft. and over shall be considered as beam shear (a 

 measure of diagonal tension), for effective widths between 3 ft. and 4.5 ft. the total shear shall be 

 divided proportionally between punching shear and beam shear. Beam shear shall be used in 

 calculating bond stress and as a measure of diagonal tension. 



(e) In the design of longitudinal joists or stringers with concrete floors, the fraction of the 

 concentrated load carried by one stringer for spacings 6 ft. or less will be taken equal to the stringer 

 spacing in feet divided by 6 ft.; with plank floors the fraction of the concentrated load carried by 

 one stringer for spacings 4 ft. or less will be taken equal to the stringer spacing in feet divided 

 by 4 ft., the maximum in each case being the full load. Outside stringers are to be designed for 

 the same load as intermediate stringers. 



(/) In the design of transverse stringers or floorbeams with concrete floors, the fraction of the 

 concentrated load carried by one floorbeam for floorbeams spaced 6 ft. or less, will be taken equal 

 to the floorbeam spacing divided by 6 ft. For floorbeams spaced 6 ft. or over the entire reactions 

 are assumed as carried by one floorbeam. Axle loads are assumed as distributed on a line 12 ft. 

 long. 



UNIFORM LIVE LOADS FOR TRUSSES. The uniform live loads for trusses of steel high- 

 way bridges as specified by the highway commissions of Illinois, Iowa and Wisconsin, the American 

 Concrete Institute, 1916, and the uniform loads as specified by the author for classes DI and D z 

 are given in Table I. The DI and D 2 loadings are to be taken as proportional for intermediate 

 spans, and are to be increased for impact. 



It will be seen that the DI loadings with impact added are practically the same as the Illinois 

 idings; while the D2 loadings with impact added are practically the same as the Iowa and Wis- 

 consin loadings. 



TABLE I. 



UNIFORM LIVE LOADS FOR HIGHWAY BRIDGES. 



UNIFORM LIVE LOADS FOR FLOORS. The Illinois Highway Commission specifies that 

 stringers and floorbeams for spans of 50 ft. and less shall be designed for a uniform live load of 125 

 Ib. per sq. ft., and of spans over 50 ft. in length for a uniform live load of 100 Ib. per sq. ft., or a 

 15-ton concentrated load for all spans. No allowance is made for impatt. 



The Iowa Highway Commission specifies a live load of 100 Ib. per sq. ft. or a 15-ton traction 

 engine for class "A" floors, and a live load of 100 Ib. per sq. -ft., or a lo-ton traction engine for class 

 " B " floors (plank floors). No allowance is made for impact. 



The Wisconsin Highway Commission specifies that floor systems and spans under 40 ft. be 

 designed for a 1 5-ton road roller. No allowance is made for impact. 



