GRAIN PRESSURES IN STORAGE BINS. 7 
TaBLEe 2.—Steel factors for horizontal reinforcing in cylindrical concrete tanks. 
[Areas of steel per foot in height per diameter squared.] 
a a 
H D2 H D2 
D D 
fs=16000 | f,=18000 | f,=20000 fs=16000 | fs=18000 | /,=20000 
0.1 | 0.000089 | 0.000079 | 0.000072 2.3 | 0.000843 | 0.000749 | 0.000675 
2 170 151 136 2.4 853 758 682 
3 243 216 194 2.5 860 765 688 
4 309 274 247 2.6 868 771 694 
5 369 328 295 2.7 874 717 700 
6 423 376 338 2.8 881 783 705 
=i 472 419 378 2.9 886 787 709 
8 516 459 413 3.0} .000891 | .000792 |} .000713 
eo 556 494 445 3.1 895 795 716 
1.0} .000593 | .000527 | .000474 3.2 899 799 719 
iat 625 556 500 3.3 903 802 722 
1.2 655 582 524 3.4 906 805 725 
1.3 682 606 546 3.5 909 808 727 
1.4 706 628 565 3.6 912 810 729 
1.5 728 647 583 3.7 914 813 731 
1.6 748 665 599 3.8 917 815 733 
Med 760 675 608 3.9 918 816 735 
1.8 783 695 626 4.0} .000920 | .000818 } .000736 
1g 797 708 638 5.0 931 827 745 
2.0} .000811 |} .000720} .000649 6.0 935 831 748 
2.1 823 731 658 ||. 7.0 936 832 749 
2.2 833 741 667 10.0 | .000937 | .000833 | .000750 
[For use of this table, see Example 2, page 11. 
HORIZONTAL REINFORCING FOR STRAIGHT WALLS OF CONCRETE 
BINS. 
In all bins other than cylindrical tanks the walls are designed as 
slabs supporting at any given level a uniform load equal to the 
lateral grain pressure at that point. 
Tables 3a, 3b, and 3c, for different allowable stresses in steel and 
concrete, give the maximum resisting moments and the steel areas 
required for different effective thicknesses of walls. Also, for dif- 
ferent conditions of continuity, constants are listed for determining 
the heights at which the size or spacing of the bars may be changed. 
In the following, the standard nomenclature for reinforced con- 
crete is used also: Let— 
L=lateral pressure of the grain in pounds per square foot. 
l=span of wall in feet. 
¢=thickness of wall in inches. 
ec =thickness of concrete outside of steel in inches. 
d=t—e=effective depth to steel in inches. 
a=area of steel per foot in height in square inches. 
M=bending moment or resisting moment in inch pounds. 
m= coefficient of continuity for figuring bending moment. 
2 
= 8 for simple spans ee ees 
2 
=10 for end spans—partial continuity oe 
= 12 for intermediate spans—full continuity = 19 
