6 BULLETIlSr •789, U. S. DEPARTMENT OE AGRICULTURE. 



If 4X^Xai'=N, not equal to 1, 



Let -yy.=D', then the formula becomes, 



V=D'X F 1- 



V 



L = IV 

 For values of Tf other than 50 pounds V and L may be determmed 

 by du-ect proportion. (See Example 4, page 14.) 



HORIZONTAL REINFORCING FOR CYLINDRICAL CONCRETE BINS. 



In a cylindrical tank the total pressure on any diameter for 1 foot 

 in height is equal to the lateral pressure per square foot at that level 

 times the diameter in feet, or LxD. This pressure, tending to burst 

 the tank, produces tension in the walls, and, smce two cross sections 

 of the wall are cut by each diameter, the total tensile stress on each 



LxD 



cross section of the wall for 1 foot in height is equal to — ^ As- 



suming that all of the tensile stress is taken by the steel reinforciag, 

 and mdicating the allowable unit stress in the steel by Js, the cross- 

 sectional area of steel required in square inches per foot in height at 

 that level is given by the formula : 



LxD 

 ^-2xfs 

 This formula may be written, 



a L 1 



D'-D^2xj, 



L H 



SiQce the pressure .factor jj is determined by jj, we can tabulate 



values for the steel factors -r^for different values of j^. (See Table 2.) 



