Concrete Silos 55 



pounds per square inch for the steel. This shows in a 

 concise form the cross-sectional area of steel required 

 in silos from 10 to 25 feet in diameter for the top foot 

 and each successive foot until a depth of 50 feet is 

 reached. The chart should be held in a vertical posi- 

 tion. Then, if the point is noted where one of the 

 heavy diagonal lines representing a silo diameter inter- 

 sects a horizontal line representing the depth of the 

 silo, the area of the steel required to resist the bursting 

 pressure on a section of the silo wall one foot wide 

 will be found on the scale directly below. The corre- 

 sponding area in common styles of reinforcement is 

 found directly above on the upper scales. 



