Section Loads on silos due to particulate materials

5.1 General

1) Loads due to particulate materials depend on:

— the range of particulate material properties;

— the variation in the surface friction conditions;

— the methods of filling and discharge.

2) The flow pattern (mass flow or funnel flow) should be determined from Figure 5.1.

3) For the determination of the flow pattern, the angle of wall friction may be obtained either by testing as described in 5.5.2 or by using the approximate values of coefficient of wall friction given in Table 7.1 and shall be calculated as follows:

4) Characteristic values for the filling and discharge loads are prescribed for the following types of silo:

— homogenizing silos and silos with a high filling velocity.

5) Any support given to the silo wall by the stiffness of the particulate material may be ignored in load calculations. This means that interaction of wall deformation and load from the stored material may be ignored.

5.2 Slender silos

1) Detailed rules for the calculation of filling loads are given in 5.2.1 and for discharge loads in 5.2.2. Simplified rules for filling and discharge are given in 5.2.3.

2)P General equations for the calculation of silo wall loads are given in 5.2.1. They shall be used as a basis for the calculation of the following design loads:

— filling loads on vertical walled sections (5.2.1);

— discharge loads on vertical walled sections (5.2.2);

— discharge loads on flat bottoms and hoppers (5.2.2).

Figure 5.1 — Limit between mass flow and funnel flow for conical and wedge-shaped hoppers

90 80 70 60 50 40 30 Angle of inclination of hopper wall a'

90 80 70 60 50 40 30 Angle of inclination of hopper wall a'

Figure 5.1 — Limit between mass flow and funnel flow for conical and wedge-shaped hoppers

5.2.1 Filling loads

1)P After filling, the values of wall frictional pressure pwf horizontal pressure p^f and vertical pressure pv at any depth shall be taken as:

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