GRAIN PRESSURES IN" STORAGE BINS. H 



EXAMPLE 2. 



Required: The area of steel in square inches per foot in height for 

 horizontal reinforcing for a cylindrical concrete tank 25 feet in 

 diameter and 100 feet in height at four levels, (1) at bottom, (2) at 

 height of 25 feet, (3) at height of 50 feet, (4) at height of 75 feet. 

 C/b= 18000). 



Frcm Table 2: 



E im . A 



At bottom^— or — ^ 

 At 25' 0-^=11 = 3 

 At50'0-g=| = 2 

 At 75' 0"^= 11=1 



■^-2 = 0.000818 ^ = 0.511 sq. in. 



-^2 = 0.000792. A = 0.495 sq. in. 



A 



-p = 0.000720 A = 0.450 sq. in. 



2^2 = 0.000527 A = 0.329 sq. in. 



From Plate II: As before, follow the vertical line at the right- 

 hand side for diameter 25 feet upward to its intersection with the 

 obhque line representing 100 feet for the height of the grain. From 

 this intersection project horizontally to curve 2 for /s = 18000, then 

 vertically to the line for diameter 25 feet of the set of radial lines for 

 steel. This last intersection will be found to be horizontally opposite 

 a point on the scale for steel areas a little above 0.5 or about 0.51 

 square inch, which equals area of steel per foot in height at the 

 bottom. 



In the same manner by starting in turn with the intersections of 

 the vertical line for 25-foot diameter with the oblique lines for 75 

 feet^ height of gi'ain, 50 feet height of grain, 25 feet height of grain, 

 the steel areas may be determined for these levels. 



The left-hand section of the plate provides a means of determining 

 the spacing of any size bar there listed to give a required area of 

 steel per foot in height. 



Any horizontal line through a required steel area will intersect the 

 obhque line for any chosen size bar on the vertical line giving its 

 required spacing. 



For the present example, by reading on the horizontal line through 

 0.51, it will be found that any of the following combinations of bars 

 and spacings wiU give the required area of steel at the bottom of 

 the tanks: 



f" rounds at . 7" on center. 



2h"hjl" or V by 1^'' flats at 7'' on center. 



2" by T^'' or IJ" by i'' or 1'' by f " flats at 9'' on center. 



f" squares at 9'' on center. 



2i " by T^'' flats at 1 0'' on center. 



2i"by-53g" or H" by A'' or IJ" by f" flats at.-_ir' on center. 



1 Height of grain equals distance from level of reinforcement to top of grain. 



