(1)P ENV 1991 provides general principles and actions for the structural design of buildings and civil engineering works including some geotechnical aspects and shall be used in conjunction with ENV 1992-1999.
(2) It may also be used as a basis for the design of structures not covered in ENV 1992-1999 and where other materials or other structural design actions are involved.
(3) ENV 1991 also covers structural design during execution and structural design for temporary structures. It relates to all circumstances in which a structure is required to give adequate performance.
(4) ENV 1991 is not directly intended for the structural appraisal of existing construction, in developing the design of repairs and alterations or, for assessing changes of use.
(5) ENV 1991 does not completely cover special design situations which require unusual reliability considerations such as nuclear structures for which specified design procedures should be used.
1.1.2 Scope of ENV 1991-4 Actions on silos and tanks
(1 )P This part provides general principles and actions for the structural design of tanks and silos including some geotechnical aspects and shall be used in conjunction with ENV 1991-1:Basis of Design, other parts of ENV 1991 and ENV 1992-1999.
(2) This part may also be used as a basis for the design of structures not covered in ENV 1992-1999 and where other materials or other structural design actions are involved.
(3) The following limitations apply to the design rules for silos:
- The silo cross section shapes are limited to those shown in figure 1.2;
- Filling involves only negligible inertia effects and impact loads;
- The maximum particle diameter of the stored material is not greater than 0,3dc.
Note: When particles are large compared to the silo wall thickness the load shall be applied as single forces.
- The stored material is free-flowing;
- The eccentricity e, of the stored material due to filling is less than 0,25dc (figure 1.2);
- The eccentricity e0 of the centre of the outlet is less than 0,250dc;
and no part of the outlet is at a distance greater than 0,3dc from the centre plane of silos with plane flow or the centre line of other silos (figure 1.2).
- Where discharge devices are used (for example, feeders or internal flow tubes), material flow is smooth and central within the eccentricity limits given above.
- The transition is on a single horizontal plane.
- The following geometrical limitations apply:
h/dc < 10 h< 100 m dc < 50 m
- Each silo is designed for a defined range of particulate material properties.
(4) The design rules from tanks apply only to tanks storing liquids at normal atmospheric pressure.
(5) ENV 1991-4 shall be used in conjunction with ENV 1991-1 and other parts of ENV 1991.