SIST EN 13084-2:2026

• Abstract:

  This document specifies particular requirements and performance criteria for the design and construction of cast-in situ concrete chimneys as well as prefabricated concrete chimneys. It identifies requirements to ensure the mechanical resistance and stability of concrete chimneys in accordance with the general requirements given in EN 13084-1:2025.; As for chimneys attached to buildings the criteria given in Clause 1 of EN 13084-1:2025 apply.; Unless otherwise stated in the following clauses the basic standard for the design of concrete structures, EN 1992-1-1:2023 applies.

• Status: Published
• Public Enquiry End Date: 22-Oct-2025
• Publication Date: 27-Oct-2026
• ICS: 91.060.40 - Chimneys, shafts, ducts
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 26-Oct-2026
• Due Date: 31-Dec-2026
• Completion Date: 28-Oct-2026
• Directive: 305/2011 - Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
• Mandate: M/105 - Mandate to CEN/CENELEC concerning the execution of standardization work for harmonized standards on chimneys, flues and specific products
• Ref Project: EN 13084-2:2026 - Free-standing chimneys - Part 2: Concrete chimneys

• Refers: SIST EN 1520:2026 - Precast lightweight concrete products with an open structure
• Effective Date: 28-Oct-2026
• Referred By: SIST EN 1998-6:2005 - Eurocode 8: Design of structures for earthquake resistance - Part 6: Towers, masts and chimneys
• Effective Date: 21-Oct-2026
• Referred By: SIST EN 1366-13:2019 - Fire resistance tests for service installations - Part 13: Chimneys
• Effective Date: 21-Oct-2026
• Referred By: SIST EN 15287-1:2008+A1:2010 - Chimneys - Design, installation and commissioning of chimneys - Part 1: Chimneys for non-roomsealed heating appliances
• Effective Date: 21-Oct-2026
• Referred By: SIST EN 13084-1:2007 - Free-standing chimneys - Part 1: General requirements
• Effective Date: 21-Oct-2026
• Revises: SIST EN 13084-2:2007 - Free-standing chimneys - Part 2: Concrete chimneys
• Effective Date: 08-May-2024

SIST EN 13084-2:2026 is the Slovene standard for free-standing chimneys - Part 2: Concrete chimneys, published by SIST. It specifies particular requirements and performance criteria for the design and construction of cast-in situ concrete chimneys and prefabricated concrete chimneys, with mechanical resistance and stability as the main focus. The document is used by engineers, manufacturers, contractors and specifiers who need a concrete chimney designed and built to the EN 13084 framework.

What does SIST EN 13084-2:2026 specify?

SIST EN 13084-2:2026 covers concrete chimneys only, including cast-in situ chimneys and prefabricated concrete chimneys. It works with EN 13084-1:2025 for the general chimney requirements, and it uses EN 1992-1-1:2023 as the basic design standard for concrete structures unless the document states something different.

For chimneys attached to buildings, the criteria in Clause 1 of EN 13084-1:2025 apply. The document is organized into clauses on scope, normative references, terms and definitions, materials, material properties, structural design, detailing provisions, workmanship and quality control, followed by two normative annexes.

Annex	What it covers
Annex A	Analysis of stresses due to thermal and other actions
Annex B	Limitations of crack widths

What are the key requirements of SIST EN 13084-2:2026?

SIST EN 13084-2:2026 sets the material rules, design checks and detailing rules that make a concrete chimney structurally reliable in service. The practical emphasis is on choosing suitable concrete and reinforcement, checking second-order effects, controlling cracking, and detailing openings and joints so the shell can carry load and remain durable.

Materials and design basis

Clause 4 links the document to concrete, mortar and steel standards. Cast-in situ chimneys use concrete strength classes from prEN 206-1:2024, but not below C25/30, while prefabricated chimneys may use normal-weight or lightweight aggregate concrete under the stated limits. In practice, the material choice affects strength, density, exposure resistance and how the chimney wall is detailed.

Clause 4 also requires bedding mortar for prefabricated elements to match the strength class of the element concrete. That keeps the joint from becoming the weak link between stacked elements.

Clause 5 takes concrete and steel properties from EN 1992-1-1:2023 or EN 1520:2011, with a special expression for the mean tensile strength of concrete, and elevated-temperature properties from EN 1992-1-2. This matters when the designer checks both normal operation and thermal effects from hot flue gases.

Structural design and verification

Clause 6 requires the designer to consider the actions given in EN 13084-1:2025 and the action combinations in EN 1990. The document also requires second-order effects in horizontal and vertical sections. For slender chimneys, thin walls or large openings, shell theory may be needed instead of only beam theory. In practice, this means the chimney cannot be checked only as a simple cantilever if geometry makes deformation effects important.

Clause 6.2.2 and 6.3.2 use partial safety factors for actions and materials, with country-specific values taken from the National Annex of the Eurocodes. The document gives recommended values for permanent, wind, thermal and seismic actions, and for concrete and reinforcement in the ultimate limit state. This is the basis for the load combinations and resistance checks that a designer documents.

Clause 6.2.4 and Annex A address thermal effects together with other actions. Thermal stresses are handled with a specific calculation method, while sun exposure need not be included. For prefabricated chimneys, thermal stress calculation is not needed if the flue gas temperature and insulation conditions in the clause are met. That can simplify design for some prefabricated solutions.

Clause 6.3.2.3 covers openings in the windshield. The document allows an approximate “virtual openings” method only within stated geometric limits, but it also warns that local reinforcement may still be needed. This is important because openings can govern local stress flow even when the global shell check is satisfactory.

Detailing, cracking and serviceability

Clause 6.3.3 and Annex B limit crack widths at serviceability level. The document assesses vertical cracks in the circumferential direction, and the maximum design crack width depends on exposure class. For severe classes XA2, XA3, XD3 and XS1 the limit is 0.2 mm, and for the other classes it is 0.3 mm. This directly affects reinforcement ratio, bar diameter and cover.

Clause 7 gives detailing rules for both cast-in situ and prefabricated chimneys. It sets minimum vertical and horizontal reinforcement, bar spacing, concrete cover, minimum wall thickness, splice allowances and special reinforcement around openings. For prefabricated chimneys, it also covers transport reinforcement, continuous vertical bar bundles, connections and opening layout. These rules matter because many chimney problems start as detailing or joint problems rather than global strength problems.

Workmanship and quality control

Clause 8 covers erection, bedding joints and reinforcement ducts. The document requires staged filling and compaction of duct concrete, and it controls bedding joint thickness and alignment of prefabricated elements. Clause 9 then sets sampling and testing frequencies for cast-in situ and prefabricated chimneys. In practice, the builder and QA team need a defined sampling plan, specimen preparation and strength reporting routine.

What terms does SIST EN 13084-2:2026 define?

SIST EN 13084-2:2026 uses the terms from EN 13084-1:2025 and adds its own definitions in Clause 3. The most useful ones are:

• Prefabricated element - a precast normal-weight or lightweight concrete member, reinforced or not, that completely encloses the flues of chimney stacks.
• Reinforcement ducts - the route used for continuous vertical reinforcement in prefabricated parts.
• Ultimate limit state (ULS) - the condition used for checking load-bearing capacity against the design effects of actions.
• Serviceability limit state (SLS) - the condition used for checking cracking and deflection in normal use.
• Design crack width, w_k - the calculated crack opening used to verify serviceability limits for the chimney wall.
• Mean tensile strength of concrete, f_ctm - the concrete tensile strength value used in the thermal and crack calculations.

Who uses SIST EN 13084-2:2026?

SIST EN 13084-2:2026 is used by structural engineers who design chimney shafts and verify load, stability and cracking. It is also used by concrete and precast manufacturers that choose concrete classes, reinforcement layouts and joint materials.

Contractors and erection teams use it for bedding joints, reinforcement ducts and staged construction. Quality control personnel and testing laboratories use it for sampling, specimen testing and acceptance of concrete and joint materials. Buyers, project managers and specifiers use it to align concrete chimney requirements with EN 13084-1 and the concrete design Eurocodes.

What changed in SIST EN 13084-2:2026 from the previous edition?

SIST EN 13084-2:2026 supersedes EN 13084-2:2007. The foreword states these significant technical changes:

• normative cross-references were adapted
• requirements and areas of application were revised
• textual formulations were clarified
• Formula (9) was corrected

Which standards are used with SIST EN 13084-2:2026?

SIST EN 13084-2:2026 relies on several other standards for design inputs and product requirements:

• EN 13084-1:2025 - gives the general chimney requirements and the attached-chimney criteria referenced in the scope.
• EN 1992-1-1:2023 - provides the basic concrete design rules used for materials, resistance, joints and detailing unless this document says otherwise.
• EN 1992-1-2 - gives the elevated-temperature material properties used in thermal assessment.
• EN 1990 - provides design values of actions and combinations of actions.
• prEN 206-1:2024 - supplies concrete performance, production, conformity and exposure-condition rules.
• EN 1520:2011 - applies to open-structure lightweight aggregate concrete and its relevant checks.
• EN 12446 - covers concrete outer wall elements used in prefabricated chimney construction.
• EN 1993-3-2 - is listed in the foreword as additionally applicable for chimney-related steel design.
• EN 13084-4 - is part of the same chimney series and is referenced for dynamic response due to wind actions.

What does the SIST EN 13084-2:2026 document contain?

SIST EN 13084-2:2026 contains material rules, structural calculation methods, detailing limits, workmanship rules and quality control requirements for concrete chimneys. It includes figures for openings and reinforcement layouts, Table 1 for crack-width limits, and formulas for material properties, second-order moments, thermal effects and crack assessment. Annex A provides the calculation method for stresses from temperature differences and other actions, while Annex B gives the crack-width verification method used at serviceability level.

SLOVENSKI STANDARD
01-december-2026
Prostostoječi dimniki - 2. del: Betonski dimniki
Free-standing chimneys - Part 2: Concrete chimneys
Freistehende Schornsteine - Teil 2: Betonschornsteine
Cheminées autoportantes - Partie 2 : Cheminées en béton
Ta slovenski standard je istoveten z: EN 13084-2:2026
ICS:
91.060.40 Dimniki, jaški, kanali Chimneys, shafts, ducts
91.100.30 Beton in betonski izdelki Concrete and concrete
products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 13084-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2026
EUROPÄISCHE NORM
ICS 91.060.40 Supersedes EN 13084-2:2007
English Version
Free-standing chimneys - Part 2: Concrete chimneys
Cheminées autoportantes - Partie 2 : Cheminées en Freistehende Schornsteine - Teil 2: Betonschornsteine
béton
This European Standard was approved by CEN on 7 September 2026.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 13084-2:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Materials . 7
4.1 Concrete . 7
4.1.1 Normal-weight concrete for cast-in situ chimneys . 7
4.1.2 Concrete for prefabricated chimneys . 7
4.2 Mortar for bedding of prefabricated elements . 7
4.3 Reinforcing steel . 7
5 Material properties . 7
6 Structural design . 9
6.1 Actions . 9
6.2 Effect of actions . 9
6.2.1 General. 9
6.2.2 Partial safety factors . 9
6.2.3 Moments of 2nd order . 9
6.2.4 Superposition of effects from thermal and other actions . 11
6.3 Verification . 12
6.3.1 General. 12
6.3.2 Ultimate limit state . 12
6.3.3 Serviceability limit state . 15
7 Detailing provisions . 15
7.1 Cast-in situ chimneys . 15
7.1.1 Minimum vertical reinforcement . 15
7.1.2 Minimum horizontal reinforcement . 16
7.1.3 Minimum reinforcement around openings . 16
7.1.4 Distance between bars . 16
7.1.5 Minimum concrete cover . 17
7.1.6 Minimum wall thickness . 17
7.1.7 Splices . 17
7.2 Prefabricated concrete chimneys . 17
7.2.1 Minimum reinforcement for transportation of prefabricated elements . 17
7.2.2 Minimum horizontal reinforcement . 17
7.2.3 Minimum concrete cover . 17
7.2.4 Minimum wall thickness . 17
7.2.5 Vertical continuous bundles of bars . 18
7.2.6 Openings . 18
8 Workmanship . 19
8.1 General. 19
8.2 Bedding joints . 19
8.3 Reinforcement ducts . 19
9 Quality control . 20
9.1 Cast-in situ chimneys . 20
9.2 Prefabricated chimneys . 20
Annex A (informative) Analysis of stresses due to thermal and other actions . 21
Annex B (normative) Limitations of crack widths . 25
Bibliography . 26

European foreword
This document (EN 13084-2:2026) has been prepared by Technical Committee CEN/TC 297 “Free-
standing industrial chimneys”, the secretariat of which is held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2027 and conflicting national standards shall be
withdrawn at the latest by April 2027.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 13084-2:2007.
— the cross-references were adapted,
— requirements and scope have been revised,
— textual formulations and editorial changes for clarification were made, and
— Formula (9) was corrected.
This document is part 2 of a series of standards as listed below:
— EN 13084-1, Free-standing chimneys — Part 1: General requirements
— EN 13084-2, Free-standing chimneys — Part 2: Concrete chimneys
— EN 13084-4, Free-standing chimneys — Part 4: Brick liners — Design and execution
— EN 13084-5, Free-standing chimneys — Part 5: Material for brick liners — Product specifications
— EN 13084-6, Free-standing chimneys — Part 6: Steel liners — Design and execution
— EN 13084-7, Free-standing chimneys — Part 7: Product specifications of cylindrical steel fabrications
for use in single wall steel chimneys and steel liners
— EN 13084-8, Free-standing chimneys — Part 8: Design and execution of mast construction with satellite
components
— EN 13084-9, Free-standing chimneys — Part 9: Lifetime management — Monitoring, inspection,
maintenance, remedial and reporting; Operations and actions required
Additionally applies:
— EN 1993-3-2, Eurocode 3: Design of steel structures — Part 3-2: Towers, masts and chimneys —
Chimneys
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United
Kingdom.
1 Scope
This document specifies particular requirements and performance criteria for the design and
construction of cast-in situ concrete chimneys as well as prefabricated concrete chimneys. It identifies
requirements to ensure the mechanical resistance and stability of concrete chimneys in accordance with
the general requirements given in EN 13084-1:2025.
As for chimneys attached to buildings, the criteria given in Clause 1 of EN 13084-1:2025 apply.
Unless otherwise stated in the following clauses, the basic standard for the design of concrete structures,
EN 1992-1-1:2023, applies.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 206-1:2026, Concrete — Specification, performance, production and conformity — Part 1: Performance,
requirements, factory production control and assessment criteria for individual values
EN 1520:2026, Precast lightweight concrete products with an open structure
EN 1992-1-1:2023, Eurocode 2: Design of concrete structures — Part 1-1: General rules and rules for
buildings, bridges and civil engineering structures
EN 1992-1-2, Eurocode 2 — Design of concrete structures — Part 1-2: Structural fire design
EN 12446, Chimneys — Components — Concrete outer wall elements
EN 13084-1:2025, Free-standing chimneys — Part 1: General requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 13084-1:2025 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
prefabricated element
precast member of normal-weight or light-weight concrete, reinforced or not, which completely encloses
the flues of chimney stacks
3.2
reinforcement duct
route for the continuous vertical reinforcement in prefabricated parts
4 Materials
4.1 Concrete
4.1.1 Normal-weight concrete for cast-in situ chimneys
The concrete strength classes given in EN 206-1:2026 but not less than C25/30 can be used for cast-in
situ chimneys. For environmental conditions, EN 206-1:2026 applies.
4.1.2 Concrete for prefabricated chimneys
4.1.2.1 Normal-weight concrete
See 4.1.1.
4.1.2.2 Light-weight aggregate concrete
The light-weight aggregate concrete for prefabricated elements shall correspond to the density-
class D1,2 or higher in accordance with Table 12 of EN 206-1:2026.
The light-weight aggregate concrete with closed structure for prefabricated elements shall correspond
to the strength classes given in EN 206-1:2026. For environmental conditions, EN 206-1:2026 applies.
The light-weight aggregate concrete with open structure for prefabricated elements shall correspond to
the strength classes given in EN 1520:2026, but strength classes less than LAC 8 shall not be used. For
environmental conditions, see EN 206-1:2026.
4.1.2.3 Reinforcement duct infill concrete
The reinforcement duct infill concrete shall have at least the same strength class as the prefabricated
elements, but not more than the next higher strength class. The flow class for consistence shall not be less
than F3 in accordance with Table 3 of EN 206-1:2026 and the maximum size of aggregate shall not
be greater than 8 mm.
4.1.2.4 Outer wall elements
Prefabricated outer wall elements shall be in accordance with EN 12446.
4.2 Mortar for bedding of prefabricated elements
The mortar of bedding joints between prefabricated elements shall have the same strength class as the
concrete of the prefabricated elements.
4.3 Reinforcing steel
For reinforcing steel, the specifications given in EN 1992-1-1:2023 apply.
5 Material properties
The material properties of concrete and reinforcing steel for normal temperature design shall be taken
from EN 1992-1-1:2023 or EN 1520:2026 with the exception of the mean tensile strength of concrete,
f , which shall be calculated in accordance with Formula (1). The influence of elevated temperatures on
ctm
the mechanical and thermal properties of concrete and reinforcing steel shall be determined from
EN 1992-1-2.
0,67
f = c × c × c × c f (1)
ctm c β v η cm
where
c is the concrete density factor:
c
ρ
c = 0,4 + 0,6
c
2 200
where
ρ is the density of concrete:
— for normal-weight concrete:
ρ = 2 200 kg/m
— for light-weight concrete:
ρ is the design value of the density of concrete corresponding to the density class in
accordance with Table M.1 of EN 1992-1-1:2023.
c is the concrete strength factor:
β
c = 0,45
β
c is the predamage factor:
v
c = 0,85 - 0,2 x t
v
c is the eccentricity factor:
η
06, +×6 c ×η
t
c =
η
1,0+×40 t
where
c is the wall thickness factor:
t
2,6+×24 t
c =
t
1,0+×40 t
η is the eccentricity:
M
η=
Nt×
M is the design value of the bending moment in the cross-section concerned, in newton
metres;
N is the design value of the axial force in the cross-section concerned, in newtons;
t is the wall thickness of the cross-section concerned, in metres.
f is the mean compressive strength of concrete, in newtons per square millimetres (N/mm ):
cm
fcm = fck + 8
where f is the characteristic compressive strength (cylinders) of concrete, in newtons per
ck
square millimetres.
For lightweight-aggregate concrete, the symbols f , f and f shall be replaced by f , f and f
ctm cm ck lctm lcm lck
respectively.
6 Structural design
6.1 Actions
Actions to be considered are given in EN 13084-1:2025. For design values of actions and combination of
actions, see EN 1990-1.
6.2 Effect of actions
6.2.1 General
The effect of actions in both horizontal and vertical cross-sections shall be calculated taking into account
moments of 2nd order.
The windshield should usually be treated in accordance with the beam theory being subjected to axial
forces, bending moments and thermal effects. For chimneys with very low slenderness and/or small wall
thickness and/or for areas with large openings additional calculations with shell theory shall be executed.
If effects on the stability are expected, the influences from creep, shrinkage and cracking shall be taken
into account.
6.2.2 Partial safety factors
Partial safety factors for actions shall be applied.
The recommended partial safety factors for actions are:
a) permanent actions
— unfavourable effect γ = 1,35
G
— favourable effect γ = 1,0
G
b) wind actions γ = 1,5
W
c) thermal effects γ = 1,5
T
d) seismic actions γ = 1,0
E
NOTE The values of the partial safety factors for actions in the ultimate limit state for use in a country can be
found in its National Annex of the Eurocodes.
6.2.3 Moments of 2nd order
6.2.3.1 General
For the determination of moments of 2nd order the mean values of the material properties can be used.
In the concrete compression zone, the following linear material law shall be used:
σε = ×
E
cm
(2)
where
σ is the stress;
E is the modulus of elasticity of concrete;
cm
ɛ is the strain.
The stiffening effect of the concrete in the tension zone can be taken into account in chimneys with
continuous vertical reinforcement.
6.2.3.2 Approximate method
The approximation is based on the following assumptions:
— full utilization of the cross-sections with respect to the local load carrying capacity;
— consideration of the tension stiffening effects of the concrete;
— no consideration of deflection effects due to imperfections and rotation of the foundation;
— constant diameter and wall thickness or nearly linear reduction of one or both of them over the
chimney height.
The design value of the 2nd order moment may be calculated as follows:
— for windshields with continuous vertical reinforcement:
2,4
  
(85 - 0, 14 ×× h) z z
II I I α
(3)
(z) = (z) + (0) × × 1 + 2, 4 × × 1 -
M MM   
100 h h
  
— for windshields without continuous vertical reinforcement with the value of α according to
Formula (5) not exceeding 0,6:
II 2 I
(z) = (1 + κ × ) × (z)
MMα
(4)
where
II
M (z) is the design value of the 2nd order bending moment at height z;
I
M (0) is the design value of the 1st order bending moment at the chimney base;
I
M (z) is the design value of the 1st order bending moment at height z;
z is the height at the considered cross-section above the top level of the foundation;
h is the height of chimney above the top level of the foundation;
κ = 0,5, if the horizontal joints do not open deeper than the centre of gravity;
κ = 0,75, if the horizontal joints open deeper than the centre of gravity;
N
α = h ×
× I
E
cm
(5)
where
N is the design value of the axial force at the chimney base;
E is the modulus of elasticity of concrete;
cm
I is the 2nd moment of area at the chimney base of the uncracked cross-section ignoring
reinforcement.
t
Id=π××
m
where
d is the mean windshield diameter at the chimney base;
m
t is the wall thickness at the chimney base.
6.2.3.3 Rotation of foundation
Rotation of the foundation causes moments of 2nd order in the windshield.
For the determination of the angle of rotation θ, Formulae (6) or (7) apply:
— for a circular raft foundation if there is no uplift
1− v
( )
II
θ M× 0,54 (6)
ER×
( )
soil
— for a foundation on end bearing piles
II
M
θ= (7)
β xk×
∑
p p p
where
II
M is the design value of the 2nd order bending moment acting on the foundation referred to
underside of the foundation;
R is the radius of the circular raft foundation;
E is the modulus of elasticity of the soil;
soil
ν is the Poisson's ratio; ν = 0,5;
x is the distance of a pile to the axis of rotation;
p
k is the spring constant of an end bearing pile;
p
β is the factor for pile interference in a grid:
p
β =
p
 
d
p
 
1+×6
 
s
p
 
where
d is the pile diameter;
p
s is the minimum spacing between the piles.
p
6.2.4 Superposition of effects from thermal and other actions
The superposition of thermal stresses and stresses from other actions is particularly difficult due to the
highly nonlinear behaviour of the material. A calcula
...