CHAPTEE XX 



SILOS OF REINFORCED CONCRETE 



Reinforced concrete forms an excellent material for the construction of 

 silos. As an example of its use for this purpose, drawings are reproduced 

 for a circular silo, 15 feet internal diameter by 30 feet high. The capacity 

 of this silo is 5299 cubic feet (see p. 281). Taking the average density 

 of the silage as 39*6 lbs. per cubic foot, which is the value given by King 

 for a silo 30 feet in height, the silo will hold 



5299 x 39-6 = 209,840 lbs. = 104 short tons fully. 



The wall of the silo is 5 inches thick. The reinforcement is in the 

 form of round iron bars which are, for the most part, f-inch diameter, 

 except in the floor where £-inch bars are used, and around the emptying 

 door-ways which are strengthened by 1-inch bars. 



The bars in the wall are arranged in horizontal and vertical sets, 

 the bars (in the form of hoops) composing the former set being spaced 

 6 inches apart in the lower two-thirds of the silo, and 9 inches apart in 

 the upper third. The vertical bars are forty in number, spaced at equal 

 distances apart circumferentially. The bars of the two systems are 

 bound together with wire where they cross each other. 



The floor of the silo is 4 inches thick, reinforced with £-inch diameter 

 bars " d" (Fig. 167) laid crosswise so as to form a mesh-work, each mesh 

 being a square of 12-inch side, the bars being tied together with wire 

 where they cross each other. The ends of these ^-inch bars are bent 

 around the lowest horizontal bar of the wall reinforcement. 



The footirjg, immediately below the wall of the silo, is 12 inches thick, 

 and, besides being strengthened by the above-described reinforcement of 

 the floor, is further armoured by two g-inch hoops connected by fifty 

 |-inch radial bars " c " (Fig. 167), the ends of which are bent around 

 the hoops. 



Both floor and footing rest upon 6 inches of hard-core. 



