Eurocode EN 1991-4. Silos and tanks

(1)This 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; (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 (5) The following limitations on the filling and discharge arrangements apply to the design rules for silos: − filling involves only negligible inertia effects and impact loads; − where discharge devices are used (for example feeders or internal flow tubes) solids flow is smooth and central. (6) Only hoppers that are conical (i.e. axisymmetric), square pyramidal or wedge-shaped (i.e. with vertical end walls) are covered by this standard. Other hopper shapes and hoppers with internals require special considerations. (7) Some silos with a systematically non-symmetric geometry are not specifically covered by this standard. These cases include a chisel hopper (i.e. a wedge hopper beneath a circular cylinder) and a diamond-back hopper. (8) The design rules for tanks apply only to tanks storing liquids at normal atmospheric pressure. (9) Actions on the roofs of silos and tanks are given in EN 1991-1-1, EN 1991-1-3 to EN 1991-1-7 and EN 1991-3 as appropriate. (10) The design of silos for reliable solids discharge is outside the scope of this standard. (11) The design of silos against silo quaking, shocks, honking, pounding and silo music is outside the scope of this standard.