UNITED STATES DEPARTMENT OF AGRICULTURE 



M BULLETIN No. 789 



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Contribation from the Bureau of Markets, 

 GEORGE LTVINGSTON, Acting Chief. 



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Washington, D. C. 



PROFESSIONAL PAPER 



October 6, 1919 



NOTES ON GRAIN PRESSURES IN STORAGE BINS. 



By W. J. Larkin, Jr., Consultant in Bulh Grain Handling. 



CONTENTS. 



Page. 



Introductton 1 



Janssen's formula 1 



Pressure factors for •vrheat in round or other 



regular concrete bins 2 



Explanation of Plate 1 3 



Determination of unit pressures in rectangular 



or ottier irregular bins 5 



Determination of unit pressures for various 



grains in bins of different materials 5 



Horizontal reinforcing for cylindrical con- 

 crete bins 6 



Horizontal reinforcing for straight walls of 

 concrete bins 7 



Determination of vertical and lateral pres- 

 sures in grain bins vrith horizontal reinforc- 

 ing for cylindrical concrete tanks by means 

 of Platen 10 



Appendix 14 



Selected list of publications on the pressure of 

 stored grain 15 



INTRODUCTION. 



The formula derived by Janssen for the determination of the 

 vertical and lateral pressures of grain in bins is one commonly used 

 by grain, elevator engineers. Most engineers, in their calculations, 

 have also made use of a table of values similar to the one here given, 

 by means of which the unit pressures are more quickly and easily 

 determined (see Table 1). In this bulletin are given rules for the 

 more advantageous application of this table, together with addi- 

 tional tables and graphical charts which should further facilitate the 

 designing of grain bins. 



JANSSEN'S FORMULA.! 



In Janssen's formula the following nomenclature is used: 

 A = area of bin in square feet. 

 P = perimeter of bin in feet. 



jB = hydraulic radius of bin= p 



Note. — This bulletin is of interest to engineers, particularly those having occasion to design grain storage 

 bins. 



1 For the derivation of Janssen's formula together with descriptions and results of diflerent experiments 

 to determine values for th« coefficient of friction of grain on bin walls and the ratio of the lateral to the 

 vertical pressure at any point, see Ketchum, Milo S., The design of walls, bins, and grain elevators, 2d ed,, 

 New York, 1911. 



108882°— 19 



