EN 1991-4:2006

(1)PThis part provides general principles and actions for the structural design of silos for the storage of particulate solids and tanks for the storage of fluids and shall be used in conjunction with EN 1990, other parts of EN 1991 and EN 1992 to EN 1999.



(2)This part includes some provisions for actions on silo and tank structures that are not only associated with the stored solids or liquids (e.g. the effects of thermal differentials, aspects of the differential settlements of batteries of silos)



(3)The following geometrical limitations apply to the design rules for silos:

-the silo cross-section shapes are limited to those shown in Figure 1.1d, though minor variations may be accepted provided the structural consequences of the resulting changes in pressure are considered;

-the following dimensional limitations apply:



hb/dc < 10

hb < l00 m

dc < 60 m



-the transition lies in a single horizontal plane (see Figure 1.1a);

-the silo does not contain an internal structure such as a cone or pyramid with its apex uppermost, cross-beams, etc. However, a rectangular silo may contain internal ties.



(4)The following limitations on the stored solids apply to the design rules for silos:

-each silo is designed for a defined range of particulate solids properties;

-the stored solid is free-flowing, or the stored solid can be guaranteed to flow freely within the silo container as designed (see 1.5.12 and Annex C);

-the maximum particle diameter of the stored solid is not greater than 0,03dc (see Figure 1.1d).



NOTE:When particles are large compared to the silo wall thickness, account should be taken of the effects of single particles applying local forces on the wall.