302 



STEEL BINS. 



CHAP. VIII. 



Case 6. Wall Sloping Outward. 6 > 90 + <'. Surface Level. Fig. 6. 

 P = w/f 2 -tan 2 (45 - 



+ tan 4 (45 

 tan 9 



(18) 



(19) 



() = .E-cos z 

 r = sin 2 



FIG. 6. 



For a wall sloping outwards, and sloping surface the use of formulas is cumbersome and the 

 calculations can be more easily made by graphic methods as explained on succeeding pages. 



Tables of Pressure on Vertical Bin Walls. The normal pressure on vertical bin walls as 

 calculated by the preceding formulas for bituminous coal, anthracite coal, sand, and ashes are 

 given in Table IV, Table V, Table VI, and Table VII, respectively. 4 In the tables column I gives 

 the normal pressure for a smooth vertical wall and horizontal surcharge, while column 4 gives 

 the normal pressure on a rough wall with an angle of friction = <'. Column 2 gives the normal 

 pressure for a smooth vertical wall and a surcharge = tf>, while column 5 gives the normal pressure 

 on a rough wall with an angle of friction = </>'. Column 3 gives the normal pressure for a smooth 

 vertical wall and a negative surcharge = <, while column 6 gives the normal pressure on a 

 rough wall with an angle of friction = <f>'. It will be seen that the pressures in columns 2 and 5 

 are identical. For a vertical wall with 8 = <j>, the normal pressures as given by Rankine's and 

 Cain's formulas are identical. 



These tables have been taken from the author's "The Design of Walls, Bins and Grain 

 Elevators." The tables of pressures and the formulas were first published in a modified form 

 by Mr. R. W. Dull, in Engineering News. 



