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BS EN 1993-4-1:2026 Eurocode 3. Design of steel structures - Silos, 2026
- undefined
- European foreword
- 0 Introduction
- 1 Scope [Go to Page]
- 1.1 Scope of EN 1993-4-1
- 1.2 Assumptions
- Figure 1.1 — Terminology used in silo structures
- 2 Normative references
- 3 Terms, definitions, symbols, sign conventions and units [Go to Page]
- 3.1 Terms and definitions
- 3.2 Symbols used in this document [Go to Page]
- 3.2.1 Latin upper-case letters
- 3.2.2 Latin lower-case letters
- 3.2.3 Greek letters
- 3.2.4 Subscripts
- 3.3 Sign conventions [Go to Page]
- 3.3.1 Conventions for global silo structure axis system for circular silos
- Figure 3.1 — Global coordinate system and loadings on a circular silo [Go to Page]
- 3.3.2 Conventions for global silo structure axis system for rectangular silos
- Figure 3.2 — Global coordinate system and loadings on a rectangular silo [Go to Page]
- 3.3.3 Conventions for structural element axes in both circular and rectangular silos
- Figure 3.3 — Local coordinate systems for walls and meridional stiffeners on a shell
- Figure 3.4 — Local coordinate systems for walls and meridional stiffeners on a box
- Figure 3.5 — Local coordinate system for circumferential ring stiffeners on a shell for directions of bending [Go to Page]
- 3.3.4 Conventions for stress resultants for circular silos and rectangular silos
- Figure 3.6 — Stress resultants in the shell silo wall
- 4 Basis of design [Go to Page]
- 4.1 Basic requirements
- 4.2 Units
- 4.3 Silo classifications [Go to Page]
- 4.3.1 Consequence Classification for silos
- 4.3.2 Structural Complexity Classification for silos
- Figure 4.1 — Dimensions used to define Structural Complexity Classes
- Table 4.1 (NDP) — Descriptions and quantified limits for parameter w for Structural Complexity Classes for silos [Go to Page]
- 4.3.3 Silo Group Categorization
- Table 4.2 (NDP) — Silo Group (SG) defined by the Structural Complexity Class (SCC), and Consequence Class (CC) [Go to Page]
- 4.4 Verification by the partial factor method [Go to Page]
- 4.4.1 Partial factors for actions on silos
- 4.4.2 Partial factors for resistances
- Table 4.3 — Partial factors for resistance
- Table 4.4 (NDP) — Numerical values for partial factors for resistance for silo structures [Go to Page]
- 4.5 Actions and environmental effects [Go to Page]
- 4.5.1 General
- 4.5.2 Wind action
- 4.5.3 Combination of particulate solids pressures with other actions
- 4.6 Geometrical data
- 4.7 Modelling of the silo for determining action effects
- 4.8 Design assisted by testing
- 4.9 Action effects for limit state verifications
- 4.10 Durability
- 4.11 Fire resistance
- 5 Properties of materials [Go to Page]
- 5.1 General
- Table 5.1 — Temperature dependent reduction factor kT
- Table 5.2 — Temperature dependent reduction factor kT,E [Go to Page]
- 5.2 Structural steels
- 5.3 Stainless steels
- 5.4 Special alloy steels
- 5.5 Toughness requirements
- 6 Basis for structural analysis [Go to Page]
- 6.1 Ultimate limit states [Go to Page]
- 6.1.1 Basis
- 6.1.2 Required checks
- 6.1.3 High cycle fatigue and cyclic plasticity (low cycle fatigue)
- 6.1.4 Allowance for corrosion and abrasion
- 6.1.5 Allowance for temperature effects
- 6.2 Serviceability limit states
- 6.3 Analysis of the structure of a shell silo [Go to Page]
- 6.3.1 Modelling of the structural shell
- 6.3.2 Methods of analysis [Go to Page]
- 6.3.2.1 General
- 6.3.2.2 Silo Group 3
- 6.3.2.3 Silo Group 2
- Figure 6.1 — Vertical deformation compatibility between ring girder and shell [Go to Page]
- 6.3.2.4 Silo Group 1
- 6.3.2.5 Silo Group 0
- 6.3.3 Geometric imperfections
- 6.4 Analysis of the box structure of a plate assembly silo [Go to Page]
- 6.4.1 Modelling of the structural box formed by an assembly of plates
- 6.4.2 Geometric imperfections
- 6.4.3 Methods of analysis
- 6.5 Analysis treatment of corrugated sheeting
- Figure 6.2 — Corrugation profile and geometric parameters
- Figure 6.3 — Corrugated sheeting and silo wall orientations
- 7 Ultimate limit state design of cylindrical shell walls [Go to Page]
- 7.1 Basis [Go to Page]
- 7.1.1 General
- 7.1.2 Silo wall design
- 7.2 Distinctions between cylindrical shell forms
- Figure 7.1 — Illustrations of cylindrical shell forms [Go to Page]
- 7.3 Resistance of isotropic welded or bolted cylindrical walls [Go to Page]
- 7.3.1 General
- 7.3.2 Evaluation of design stress resultants
- 7.3.3 Plastic limit state
- 7.4 Resistance of isotropic cylindrical walls under axial compression [Go to Page]
- 7.4.1 Elastic buckling under uniform axial compression
- Table 7.1 — Fabrication tolerance quality classes [Go to Page]
- 7.4.2 Elastic buckling under non-uniform axial compression
- Figure 7.2 — Representation of local distribution of axial membrane stress resultant around the circumference [Go to Page]
- 7.4.3 Elastic axial compression buckling above a horizontal lap joint
- 7.4.4 Simple treatment of buckling resistance above a discrete support
- 7.4.5 Buckling resistance under axial compression evaluation
- 7.5 Resistance of isotropic cylindrical walls under external pressure, internal partial vacuum and wind [Go to Page]
- 7.5.1 Buckling of the cylindrical wall
- Figure 7.3 — Notation for stepped wall with different heights of strakes
- Table 7.2 — Values of external pressure buckling parameter Cb [Go to Page]
- 7.5.2 Upper edge restraint by an eaves ring
- 7.5.3 Secondary ring stiffeners
- 7.5.4 Resistance of isotropic cylindrical walls under membrane shear
- 7.6 Interactions between axial compression, circumferential compression and membrane shear in isotropic walls
- 7.7 Isotropic walls under cyclic loads [Go to Page]
- 7.7.1 Fatigue, LS4
- 7.7.2 Cyclic plasticity, LS2
- 7.8 Resistance of isotropic walls with vertical stiffeners [Go to Page]
- 7.8.1 General
- 7.8.2 Plastic limit state
- 7.8.3 Buckling under axial compression
- 7.8.4 Buckling under external pressure, partial vacuum or wind
- 7.8.5 Buckling under membrane shear
- 7.9 Resistance of horizontally corrugated cylindrical walls [Go to Page]
- 7.9.1 General
- Figure 7.4 — Common arrangements for cold-formed vertical stiffeners on horizontally corrugated shells [Go to Page]
- 7.9.2 Tolerance requirements
- 7.9.3 Plastic limit state
- Figure 7.5 — Typical bolt arrangement for a panel of a corrugated silo [Go to Page]
- 7.9.4 Buckling under axial compression [Go to Page]
- 7.9.4.1 General
- 7.9.4.2 Unstiffened corrugated wall
- 7.9.4.3 Stiffened corrugated cylindrical walls treated as carrying axial compression only in the stiffeners
- Figure 7.6 — Evaluation of restraint stiffness against stiffener column buckling using a curved wall treatment
- Figure 7.7 — Cold-formed stiffeners with edge stiffened flanges: buckling curve b (as in EN 1993-1-3)
- Figure 7.8 —Stiffeners with unstiffened flanges: buckling curve c (as in EN 1993-1-1) [Go to Page]
- 7.9.4.4 Stiffened corrugated cylindrical wall treated as an orthotropic shell
- 7.9.4.5 Local, distortional and flexural torsional buckling of stiffeners
- 7.9.5 Buckling of corrugated cylindrical shells under external pressure, partial vacuum or wind
- 7.9.6 Buckling of corrugated cylindrical shells under membrane shear
- 7.10 Vertically corrugated cylindrical walls with ring stiffeners [Go to Page]
- 7.10.1 General
- 7.10.2 Plastic limit state
- 7.10.3 Buckling under axial compression
- 7.10.4 Buckling under external pressure, partial vacuum or wind
- 7.10.5 Membrane shear
- 7.11 Detailing for openings in cylindrical walls [Go to Page]
- 7.11.1 General
- 7.11.2 Rectangular openings
- Figure 7.9 — Typical stiffening arrangements for openings in silo walls
- 8 Support conditions for cylindrical walls [Go to Page]
- 8.1 Shell with its base fully supported
- 8.2 Isotropic shell supported by a skirt
- 8.3 Isotropic cylindrical shell wall with engaged columns
- Figure 8.1 — Different arrangements for support of silo with hopper [Go to Page]
- 8.4 Framework support beneath an isotropic walled silo
- Figure 8.2 — Simple tour support framework
- Figure 8.3 — Standard eight support framework
- Figure 8.4 — Alternative eight support framework [Go to Page]
- 8.5 Discretely supported isotropic cylindrical shell without a ring girder
- 8.6 Discretely supported isotropic cylindrical shell with a ring girder
- 8.7 Discretely supported isotropic cylindrical shell with an intermediate ring [Go to Page]
- 8.7.1 Intermediate ring at the ideal height
- Figure 8.5 — Discretely supported silo with intermediate ring [Go to Page]
- 8.7.2 Intermediate ring placed below the ideal height
- 8.8 Discretely supported isotropic silo with columns beneath the hopper
- 8.9 Local support details and ribs for load introduction in isotropic cylindrical walls [Go to Page]
- 8.9.1 Local supports beneath the wall of an isotropic cylinder
- Figure 8.6 — Typical details of supports [Go to Page]
- 8.9.2 Local ribs for load introduction into isotropic cylindrical walls
- Figure 8.7 — Typical details of loading rib attachments [Go to Page]
- 8.10 Anchorage at the base of an isotropic walled silo
- 8.11 Isotropic walled cylindrical shells with vertical stiffeners with the base fully supported
- 8.12 Corrugated stiffened cylindrical shells with the base fully supported
- 9 Ultimate limit state design of isotropic conical hoppers [Go to Page]
- 9.1 Basis [Go to Page]
- 9.1.1 General
- 9.1.2 Distinctions between hopper shell forms
- 9.2 Isotropic hopper wall design
- 9.3 Resistance of isotropic conical hoppers [Go to Page]
- 9.3.1 General
- Figure 9.1 — Hopper shell segment [Go to Page]
- 9.3.2 Isotropic unstiffened welded or bolted hoppers [Go to Page]
- 9.3.2.1 General
- 9.3.2.2 Plastic mechanism or rupture in the hopper body
- 9.3.2.3 Rupture at the transition junction
- Figure 9.2 — Hopper transition joint: potential for rupture [Go to Page]
- 9.3.2.4 Plastic mechanism at thickness changes or at the transition
- Figure 9.3 — Plastic collapse of conical hopper [Go to Page]
- 9.3.2.5 Local flexure in the hopper below the transition
- Figure 9.4 — Notation for the top of a conical hopper [Go to Page]
- 9.3.2.6 Hoppers that are part of a silo resting on discrete supports beneath the cylindrical wall
- 9.3.2.7 Buckling in shell hoppers
- 9.4 Considerations for special hopper structures [Go to Page]
- 9.4.1 Supporting structures
- 9.4.2 Hoppers supported on a structural framework
- 9.4.3 Column supported hopper
- 9.4.4 Unsymmetrical hopper
- Figure 9.5 — Unsymmetrical hopper with engaged columns in cylinder [Go to Page]
- 9.4.5 Stiffened conical hoppers
- 9.4.6 Multi-segment conical hoppers
- 10 Ultimate limit state design of transition junctions and base rings in circular silos [Go to Page]
- 10.1 Basis [Go to Page]
- 10.1.1 General
- 10.1.2 Transition ring and ring girder design
- 10.1.3 Distinctions between transition junction forms
- 10.1.4 Modelling of isotropic transition junctions
- Figure 10.1 — Example ring forms [Go to Page]
- 10.1.5 Limitations on ring placement
- 10.2 Analysis of the transition junction [Go to Page]
- 10.2.1 General
- Figure 10.2 — Example showing membrane stresses developed in an annular plate ring and adjacent shell when the ring is eccentric [Go to Page]
- 10.2.2 Uniformly supported isotropic transition junctions
- Figure 10.3 — Effective section of the cylinder / hopper / ring transition
- Figure 10.4 — Notation for simple annular plate transition junction
- Figure 10.5 — Transition junction without added ring
- Figure 10.6 — Local pressures and membrane stress resultant loadings on the transition ring [Go to Page]
- 10.2.3 Isotropic transition junction ring girder above discrete supports
- Figure 10.7 — Eccentricities of vertical loads at a ring girder [Go to Page]
- 10.3 Structural resistances for isotropic junctions [Go to Page]
- 10.3.1 General
- 10.3.2 Resistance to plastic limit state [Go to Page]
- 10.3.2.1 General
- 10.3.2.2 Plastic resistance based on elastic evaluation
- 10.3.2.3 Plastic resistance based on plastic evaluation
- 10.3.3 Resistance to in-plane buckling
- 10.3.4 Resistance to out-of-plane buckling and local shell buckling near the junction [Go to Page]
- 10.3.4.1 General
- 10.3.4.2 Local shell buckling near the junction
- 10.3.4.3 Annular plate transition junction
- 10.3.4.4 T section transition junction
- 10.4 Limit state verifications for isotropic transition junctions [Go to Page]
- 10.4.1 Uniformly supported transition junctions
- 10.4.2 Transition junction ring girder
- 10.5 Considerations concerning support arrangements for the junction [Go to Page]
- 10.5.1 Skirt supported junctions
- 10.5.2 Column supported junctions and ring girders
- 10.5.3 Base ring
- 11 Ultimate limit state design of circular conical roof structures [Go to Page]
- 11.1 Basis
- 11.2 Distinctions between roof structural forms [Go to Page]
- 11.2.1 Descriptors for roofs
- 11.3 Resistance of circular conical isotropic roofs on silos [Go to Page]
- 11.3.1 Shell or unsupported roofs
- 11.3.2 Framed or supported roofs
- 11.3.3 Profiled sheeting roofs
- 11.3.4 Eaves junction (roof to shell junction)
- 12 Ultimate limit state design of rectangular and polygonal silos [Go to Page]
- 12.1 Basis
- 12.2 Classification of polygonal structural forms [Go to Page]
- 12.2.1 Unstiffened silos
- 12.2.2 Stiffened silo
- 12.2.3 Silos with ties
- Figure 12.1 — Plan view of tied rectangular box and multiple cells
- Figure 12.2 — Typical details of wall panel and tie connections [Go to Page]
- 12.3 Resistance of unstiffened vertical walls
- 12.4 Resistance of silo walls composed of stiffened or corrugated plates [Go to Page]
- 12.4.1 General
- Figure 12.3 — Typical vertical section through a corrugated rectangular silo wall
- Figure 12.4 — Shear response of corrugated wall [Go to Page]
- 12.4.2 General bending from direct action of the stored material
- Figure 12.5 — Bending neutral axis under combined horizontal pressure and frictional traction (vertical section) [Go to Page]
- 12.4.3 Membrane stresses from diaphragm action
- Figure 12.6 — Membrane forces induced in walls by particulate solids pressures or wind loading [Go to Page]
- 12.4.4 Local bending action from the stored material and/or equipment
- Figure 12.7 — Possible causes of local bending in corrugated plates [Go to Page]
- 12.5 Silos with internal ties [Go to Page]
- 12.5.1 Forces in internal ties due to particulate solids pressure on them
- Figure 12.8 — Evaluation of factor β for internal ties
- Figure 12.9 — Corner ties for which β = 0,7 [Go to Page]
- 12.5.2 Modelling and principles of calculation of ties
- Figure 12.10 — Sections through a silo with internal ties
- Figure 12.11 — Forces and deformation in a flexible tie fixed on horizontal elastic supports
- Figure 12.12 — Tie tension forces acting on the structural walls [Go to Page]
- 12.5.3 Load cases for silos with internal ties
- 12.5.4 Vertical stiffeners on silos with internal ties
- 12.6 Strength of pyramidal hoppers
- Figure 12.13 — Unsymmetrical hopper with inclined ribs [Go to Page]
- 12.7 Vertical stiffeners on box walls
- 12.8 Support requirements for plate assemblies
- 13 Serviceability requirements [Go to Page]
- 13.1 General
- 13.2 Deflections of stiffened and unstiffened isotropic cylindrical shell walls
- 13.3 Deflections of stiffened and unstiffened corrugated cylindrical shell walls
- 13.4 Conical hoppers [Go to Page]
- 13.4.1 Basis
- 13.4.2 Vibration
- 13.5 Rectangular and polygonal silos [Go to Page]
- 13.5.1 Basis
- 13.5.2 Deflections
- Annex A (informative) Simplified rules for isotropic walled circular silos in Silo Group 1
- A.1 Use of this Annex
- A.2 Scope and field of application
- A.3 Action combinations for Silo Group 1
- A.4 Action effect assessment
- A.5 Ultimate limit state assessment
- A.5.1 General
- A.5.2 Isotropic welded or bolted cylindrical walls
- A.5.2.1 Plastic limit state
- A.5.2.2 Axial compression
- A.5.2.3 External pressure, internal partial vacuum and wind
- A.5.3 Conical welded or bolted hoppers
- Figure A.1 — Hopper global equilibrium
- A.5.4 Transition junction
- Figure A.2 — Notation for a simple transition junction
- Annex B (informative) Simplified rules for transition junction ring girders in circular silos with horizontally corrugated wall and vertical stiffeners
- B.1 Use of this annex
- B.2 Scope and field of application
- Figure B.1 — Illustration of fully supported vertical stiffeners
- B.3 Evaluation of the circumferential force in the transition ring
- Figure B.2 — Vertical forces acting at the level of the transition
- B.4 Evaluation of the circumferential force in the transition ring
- B.4.1 Geometry of the transition ring
- Figure B.3 — Examples of transition ring sections
- B.4.2 Determination of the circumferential force in the ring
- Figure B.4 — Forces acting on the transition ring
- B.5 Determination of the buckling resistance of the transition ring
- Annex C (informative) Formulae for membrane stress resultants in conical hoppers
- C.1 Use of this annex
- C.2 Scope and field of application
- C.3 General hopper theory pressures (as per EN 1991-4)
- C.4 Uniform normal pressure po with frictional traction μpo
- C.5 Linearly varying normal pressure from p1 at apex to p2 at transition with frictional traction μp
- C.6 “Radial stress field” normal pressure pattern with triangular switch stress below the transition
- Bibliography [Go to Page]