Silo walls

A horizontal load shall be applied to the silo walls. The load is equivalent to the mass of the particulate material multiplied by the value of the earthquake acceleration. The horizontal distribution of the pressure due to seismic actions for circular and rectangular silos is shown in Figure C3. The horizontal pressure is constant over the height of the silo except near the top of the silo where the resultant of the seismic pressure and the filling or discharge pressure shall not be less than...

Committees responsible for this Draft for Development

The preparation of this Draft for Development was entrusted by Technical Committee B 525, Building and civil engineering structures, to Subcommittee B 525 1, Actions (loadings) and basis of design, upon which the following bodies were represented British Constructional Steelwork Association British Iron and Steel Producers' Association British Masonry Society Concrete Society Department of the Environment (Building Research Establishment) Department of the Environment (Property and Buildings...

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Maximum load magnifier

1) P The load magnifier C accounts for a number of phenomena occurring during discharge of the silo. The magnitude of the load magnifier increases with increasing material strength. 2) An appropriate laboratory test method for the parameter C has not yet been developed. The load magnifiers are based on experience and apply to silos with conventional filling and discharge systems and built to standard engineering tolerances. 3) For materials not listed in Table 7.1, the maximum wall load...

National foreword

This Draft for Development has been prepared by Subcommittee B 525 1 and is the English language version of ENV 1991-4 1995 Eurocode 1 Basis of design and actions on structures Part 4 Actions in silos and tanks published by the European Committee for Standardization (CEN). This document does not have a parallel British Standard and, therefore, it has been published for use in the United Kingdom (UK) without any National Application Document. ENV 1991-4 1995 results from a programme of work...

Or to your national standards organization National Application Documents NADs

13) In view of the responsibilities of authorities in member countries for safety, health and other matters covered by the essential requirements of the Construction Products Directive (CPD), certain safety elements in this ENV have been assigned indicative values which are identified by (boxed values). The authorities in each member country are expected to review the boxed values and may substitute alternative definitive values for these safety elements for use in national application. 14)...

Revisions

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Section Design situations

1)P The general format given in ENV 1991-1 for design procedures is applicable. NOTE This does not mean that clauses and values specified for buildings in ENV 1991-1 may be applied to silos and tanks. 2)P Selected design situations shall be considered and critical load cases identified. For each critical load case the design values of the effects of actions in combination shall be determined. 3)P The combination rules depend on the verification under consideration and shall be identified in...

Section Representation of actions

1)P The structural form of the silo shall be selected to give low sensitivity to load deviations. 2)P Loads due to particulate materials shall be calculated for filing and for discharge. The magnitude and distribution of the design loads depend on the silo structure, the stored material properties and the flow patterns which arise during the process of emptying. 3) The inherent variability of stored materials and simplifications in the load models lead to differences between actual silo loads...

Table B Recommended tests

The stored material strength parameters c, jc and j are calculated as follows jc arctan (t - tf2) 0,5sr) (B3) 4) The strength of cohesionless materials, (c 0), is described by one parameter, the angle of internal friction j, (then is equal to jc). NOTE A standard triaxial test may be used in preference to the test described above. Figure B4 Test method for determining the angles of internal friction j and jc and the cohesion c at the preconsolidation level sr Figure B4 Test method for...

Testing particulate materials

1)P Testing shall be carried out on representative samples of the particulate material. The mean value for each material property shall be determined making proper allowance for variations in secondary parameters such as composition, grading, moisture content, temperature, age, electrical charge due to handling and production method. 2)P The mean test values shall be adjusted by conversion factors to derive extreme values. The conversion factors shall be selected to allow for variability of the...

This publication is not to be regarded as a British Standard

An ENV or European Prestandard is made available for provisional application, but it does not have the status of a European Standard. The aim is to use the experience gained to modify the ENV so that it can be adopted as a European Standard (EN). For consideration of transformation of an ENV into an EN, it is important to get as much feedback as possible from practising engineers. Such feedback is therefore strongly encouraged and the users of this document are invited to comment on its...

Vertical walled section

1)P The discharge loads are composed of a fixed load and a free load, called a patch load. 2) The fixed loads pwe, Phe are obtained as follows Cw and Ch are load magnifiers according to expressions (5.22) and (5.23). For silos unloaded from the top (no flow) In other slender silos the wall pressure magnifier and the horizontal load magnifier are Cw 1,1 and Ch C0 (see 7.1) (5.23) 3) The magnitude of the discharge patch pressure Pp is Phe is calculated from expression (5.21). b depends on the...

Simplified method for filling and discharge

Bulk Material Density Method

1 For silos, where dc is less than 5m a simplified method for considering filling and discharge processes may be applied. In this procedure, the patch loads according to 5.2.1 and 5.2.2 may be adjusted by increasing the horizontal pressures. 2 For concrete silos, silos with stiffeners and silos with non circular cross-sections shapes the increased horizontal pressures for filling Phf,s and discharge Phe,s are Phf is calculated from expression 5.3 Phe is calculated from expression 5.21 b is...

Coefficient of wall friction pm for the determination of pressures

Coefficient Friction Test Method

A sample of the particulate material is sheared along a surface representing the silo wall a sample with corrugation in the case of corrugated steel silos and the friction force at the sheared surface is measured. The test apparatus is shown in Figure B1. The diameter of the box shall be at least 40 times the maximum particle size and the compacted height H of the sample shall be between 0,15D and 0,20D. In the case of wall samples with irregularities such as corrugations the box size shall be...

Normative references

This European Prestandard incorporates by dated or undated reference, provisions from other standards. These normative references are cited in the appropriate places in the text and publications listed hereafter. ISO 3898 1987, Basis of design for structures Notations. General symbols. NOTE The following European Prestandards which are published or in preparation are cited at the appropriate places in the text and publications listed hereafter. ENV 1991-1, Eurocode 1 Basis of design and actions...

Flat bottoms

Concrete Silo Design

1 Vertical loads acting on fiat or shallow silo bottoms inclinations a lt 20 shall be calculated as follows pvt Cb pv 5.13 pv is calculated using expression 5.4 Cb is a bottom load magnifier to account for the uneven load distribution calculated using expression 5.14 Figure 5.2 Side elevation and plan view of the patch load Figure 5.2 Side elevation and plan view of the patch load 1 P When a gt 20 see Figure 5.3 the pressure normal to the inclined hopper wall pn is calculated as follows x is a...

Eurocode programme

7 Work is in hand on the following Structural Eurocodes, each generally consisting of a number of parts EN 1991 Eurocode 1 Basis of design and actions on structures EN 1992 Eurocode 2 Design of concrete structures EN 1993 Eurocode 3 Design of steel structures EN 1994 Eurocode 4 Design of composite steel and concrete structures EN 1995 Eurocode 5 Design of timber structures EN 1996 Eurocode 6 Design of masonry structures EN 1997 Eurocode 7 Geotechnical design EN 1998 Eurocode 8 Design of...