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R I ' UAL ENGINEERING. 



1M) 



Etoads with Oil, by T. IT. MacDonald ; and Standard Sizes of Crushed St. me 

 from the Standpoint of the Producer, by R. W. Scherer. A special report on 

 Reinforced Concrete Slab Bridge Design Based on Full-Sized Tests, by A. T. 

 Goldbeck, is noted below. 



Reinforced concrete slab bridge design based on full-sized tests, A. T. 

 Goxdbecx if. S. Dept. Agr., PubUo Roads, 1 (IMS), No. 5, pp. 3-7, figs. 7).— 

 This paper summarizes the results of experimental work on the design of rein- 

 forced concrete slab bridges as conducted by the Bureau of Public Roads, 

 dealing especially with effective width. 



It is shown that when the load is placed in the center of the slab and the 

 width of the slab is more than about twice the span length the effective width 

 may be considered as equal to seven-tenths of the span length of the slab. 

 With reference to slabs having widths less than twice their span, the following 

 table shows effective widths which may be used for spans up to 16 ft. at least 

 and probably for longer spans: 



Effective widths of concrete slabs. 



With reference to slabs having two loads, it is pointed out that the effective 

 widths may, in general, be assumed as equal to the effective width due to a 

 single load plus 4 ft. 



With reference to eccentric loads, the effective width to be used in design may 

 be calculated as follows: (1) When the distance of the load from the nearest 

 side is more than half of the effective width of the centrally loaded slab, use tin- 

 effective width for central loads, and (2) when the distance of the load from 

 the side of the slab is less than half the effective width under central loads, the 



effective width is to be taken equal to -~-° + D, in which b c = the effective width 



of the slab under central loads and Z)=the distance of the load to the nearest 

 .side of the slab. In order to make a slab bridge eccentrically loaded equal in 

 strength to one centrally loaded, it is necessary to supply extra strength at the 

 sides by means of a parapet wall. The following procedure for the design is 

 given: (1) Use the formulas for narrow rectangular beams, substituting for 

 the breadth ft the value obtained from the above table, (2) determine the loss 

 in effective width due to the assumed eccentricity of the load, and (3) supply 

 the deficiency by designing the curb of the parapet to provide a resisting moment 

 equal to that of the slab width lost due to eccentricity. Allowance will have to 

 be made for the stiffness of the section under the parapet. An unfinished test 

 thus far indicates that this method of design is safe at least. 



Earm machinery problems under war conditions, E. A. White (Gas Engine, 

 20 (1918), No. 8, pp. 151-155). — This paper gives extracts from an address 

 presented at the W T ar Conference at the University of Illinois, on January 30, 

 1918. A general review of the situation at that time is given. 



Earm tractor engineering charts, J. Jandesek (Gas Engine, 20 (1918), No. 

 8, pp. 113-118, figs. 4). — Engineering charts showing graphs of data are given, 



