SIST EN 13084-4:2005
(Main)Free-standing chimneys - Part 4: Brick liners - Design and execution
Free-standing chimneys - Part 4: Brick liners - Design and execution
This European Standard specifies special requirements and performance criteria for the design and construction of lining systems made of brickwork for free-standing industrial chimneys. Current European practice favours sectional liners and the statements of the standard are mainly devoted to such solutions but are also largely applicable to base supported independent and stayed liners. The differences in the design and construction of the two last types are covered by Annex A. This European Standard identifies requirements to ensure mechanical resistance and stability of liners in accordance with the general requirements given in EN 13084-1.
Lining systems comprise some or all of the following:
chimney liner including duct entry;
insulation;
liner support;
space between liner and concrete windshield.
Gas flow calculations to determine liner sizes are covered by EN 13084-1.
Freistehende Schornsteine - Teil 4: Innenrohre aus Mauerwerk - Entwurf, Bemessung und Ausführung
Diese Europäische Norm behandelt die besonderen Anforderungen und die Leistungskriterien für Entwurf, Bemessung und Ausführung von Innenrohrkonstruktionen aus Mauerwerk für freistehende Industrieschornsteine. In der gängigen europäischen Praxis werden aus einzelnen Abschnitten bestehende Innenrohre (Etagen-Innenrohre) bevorzugt, und die Festlegungen der Norm beziehen sich hauptsächlich auf diese Lösungen, gelten aber auch weitestgehend für unten abgestützte freistehende und horizontal abgestützte Innenrohre. Diese Europäische Norm beschreibt die Anforderungen an die mechanische Festigkeit und Stabilität von Innenrohren entsprechend den allgemeinen Anforderungen nach EN 13084-1.
Innenrohrkonstruktionen bestehen vollständig oder teilweise aus folgenden Teilen:
- Schornsteininnenrohr einschließlich Abgaskanal-Einführung;
- Wärmedämmung;
- Innenrohrabstützung;
- Raum zwischen Innenrohr und Beton-Tragrohr.
Strömungstechnische Berechnungen zur Bestimmung der Innenrohrmaße sind in EN 13084-1 angegeben.
Cheminées indépendantes - Partie 4: Parois intérieurs en terre cuite - Planification et exécution
La présente Norme européenne spécifie les exigences et critères de performance particuliers applicables à la conception et à la construction des systèmes de conduit intérieur en briques de terre cuite pour les cheminées industrielles autoportantes. La pratique courante en Europe favorise les conduits en sections ; les exigences de la présente norme concernent principalement ces solutions, mais elles sont aussi largement applicables aux conduits portés par la base indépendants et étayés. La présente Norme européenne définit les exigences permettant de garantir la résistance mécanique et la stabilité des conduits intérieurs, conformément aux exigences générales données dans l'EN 13084-1.
Les systèmes de conduit intérieur sont constitués de tout ou partie des éléments suivants :
- le conduit intérieur de cheminée avec une arrivée de gaine ;
- l'isolation ;
- le support du conduit intérieur ;
- l'espace entre le conduit intérieur et le brise-vent en béton.
Les calculs de débit de gaz visant à déterminer la taille des conduits intérieurs sont expliqués dans l'EN 13084-1.
Prostostoječi dimniki - 4. del: Notranje zidane cevi - Projektiranje in izvedba
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2005
1DGRPHãþD
SIST EN 13084-4:2004
3URVWRVWRMHþLGLPQLNLGHO 1RWUDQMH]LGDQHFHYL3URMHNWLUDQMHLQL]YHGED
Free-standing chimneys - Part 4: Brick liners - Design and execution
Freistehende Schornsteine - Teil 4: Innenrohre aus Mauerwerk - Entwurf, Bemessung
und Ausführung
Cheminées indépendantes - Partie 4: Parois intérieurs en terre cuite - Planification et
exécution
Ta slovenski standard je istoveten z: EN 13084-4:2005
ICS:
91.060.40 Dimniki, jaški, kanali Chimneys, shafts, ducts
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN 13084-4
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2005
ICS 91.060.40 Supersedes EN 13084-4:2002
English Version
Free-standing chimneys - Part 4: Brick liners - Design and
execution
Cheminées indépendantes - Partie 4: Conduits intérieurs Freistehende Schornsteine - Teil 4: Innenrohre aus
en briques de terre cuite - Conception et mise en oeuvre Mauerwerk - Entwurf, Bemessung und Ausführung
This European Standard was approved by CEN on 29 April 2005.
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 Central Secretariat 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 13084-4:2005: E
worldwide for CEN national Members.
Contents
Page
Foreword .5
1 Scope .6
2 Normative references .6
3 Terms, definitions and symbols .6
3.1 Terms and definitions.6
3.2 Symbols.8
4 Material .8
4.1 General .8
4.2 Brickwork.8
4.2.1 General .8
4.2.2 Thermal effects .9
4.2.3 Classification and chemical attack.9
4.3 Insulation.10
5 General design requirements.11
5.1 General .11
5.2 Minimum wall thickness .11
5.3 Liner supports.11
5.4 Openings .12
5.5 Ventilation.12
5.6 Protective coatings.12
5.7 Accessories.12
5.7.1 Joints .12
5.7.2 Compensators.13
5.7.3 Ducts and fans .13
6 Structural design.13
6.1 Actions.13
6.1.1 General .13
6.1.2 Wind actions.13
6.1.3 Seismic actions.13
6.1.4 Thermal effects .13
6.1.5 Internal pressure and explosions .14
6.2 Resistances.14
6.3 Verification .14
6.3.1 Ultimate limit state .14
6.3.2 Serviceability limit state .17
6.3.3 Stress calculations in the ultimate limit state.17
6.3.4 Elastic stability.18
7 Execution.18
7.1 Imperfections .18
7.2 Tolerances.18
8 Inspection and maintenance.19
8.1 General .19
8.2 Inspection aspects.19
8.2.1 Brick liner .19
8.2.2 Insulation.20
8.3 Frequency.20
8.4 Performance .20
Annex A (informative) Structural design of base supported liners .22
A.1 General .22
A.2 Elastic stability.22
A.2.1 General .22
A.2.2 Elastic stability of the uncracked tube.22
A.2.3 Elastic stability of free standing vertical columns .24
A.2.4 Elastic stability of a half tube.25
A.2.5 Comparison of the three calculation methods and conclusions .26
Annex B (normative) Openings .29
Annex C (informative) Compensators.30
Annex D (informative) Dynamic effects .32
Annex E (informative) Strengthening – reinforced brickwork.35
E.1 Steel bands, fitted outside the liner.35
E.1.1 Stresses in the liner.35
E.1.2 Plain steel bands.36
E.1.3 Steel bands fitted with springs .36
E.2 Reinforced brickwork .39
E.2.1 General .39
E.2.2 Dimensioning .39
E.2.3.1 Bricks .39
E.2.3.2 Mortar .39
E.2.3.3 Reinforcing steel .39
E.2.4 Corrosion protection .39
E.2.5 Execution.40
Annex F (informative) Thermal effects.41
Thermal stresses .41
Annex G (informative) Drying and start up.43
G.1 New Liners.43
G.1.1 General .43
G.1.2 Externally insulated liners.43
G.1.3 Uninsulated liners.43
G.2 Old brick liners.44
Figures
Figure A.A1 — The critical height of a free standing uncracked brick liner . 24
Figure A.A2 — The critical height of cracked and uncracked brick liners. 27
Figure C.C1 — Example of a liner joint with compensator . 31
Figure D.D1 — Lowest relevant mode shape of liner. 34
Figure D.D2 — Relationship between h/r and γ . 34
Figure E.E1 — Steel bands fitted with springs . 38
Figure E.E2 — Integral reinforcement section with shaped bricks . 40
TablesTable 1 — Main symbols . 8
Table 2 — Minimum wall thickness for brickwork liners . 11
Table 4 — Characteristic values of mechanical properties of brickwork. 14
a
Table 5 — Combination of actions for persistent design situations . 16
Table 5 N – Partial safety factors γG and γQi for actions. 16
Table 6 N — Partial Safety factors γM for brickwork . 17
Table A.1 — Critical height as a function of wall thickness . 25
Table A.2 — Calculation results with given tube dimensions . 26
Table A.3 — Maximum liner height and minimum wall thickness as a function of diameter . 28
Foreword
This document (EN 13084-4:2005) has been prepared by Technical Committee CEN/TC 297 “Free-standing
industrial chimneys”, the secretariat of which is held by DIN.
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 February 2006, and conflicting national standards shall be withdrawn
at the latest by February 2006.
This document is part 4 of a package of standards as listed below:
EN 13084-1, Free-standing industrial chimneys - Part 1: General requirements.
EN 13084-2, Free-standing chimneys - Part 2: Concrete chimneys.
prEN 13084-4, Free-standing chimneys - Part 4: Brick liners – Design and execution.
EN 13084-5, Free-standing chimneys - Part 5: Materials 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 chimneys and steel liners.
EN 13084-8, Free-standing chimneys – Part 8: Design and execution of mast construction with satellite
components.
Additionally applies:
EN 1993-3-2, Eurocode 3: Design of steel structures – Part 3-2: Towers, masts and chimneys –
Chimneys
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
and United Kingdom.
1 Scope
This European Standard specifies special requirements and performance criteria for the design and
construction of lining systems made of brickwork for free-standing industrial chimneys. Current European
practice favours sectional liners and the statements of the standard are mainly devoted to such solutions but
are also largely applicable to base supported independent and stayed liners. This European Standard
identifies requirements to ensure mechanical resistance and stability of liners in accordance with the general
requirements given in EN 13084-1.
Lining systems comprise some or all of the following:
chimney liner including duct entry;
insulation;
liner support;
space between liner and concrete windshield.
Gas flow calculations to determine liner sizes are covered by EN 13084-1.
2 Normative references
The following referenced documents are indispensable for the application 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 1052-1, Methods of test for masonry Part 1: Determination of compressive strength.
EN 1052-2, Methods of test for masonry Part 2: Determination of flexural strength.
EN 13084-1:2000, Free-standing industrial chimneys — Part 1: General requirements.
EN 13084-5:2005, Free-standing chimneys — Part 5: Materials for brick liners — Product specifications.
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this European Standard, the terms and definitions given in EN 13084-1:2000 together with
the following apply.
3.1.1
base supported liner
liner which is supported vertically only at the liner base
3.1.2
independent liner
base supported liner which has no other horizontal support or restraint
3.1.3
stayed liner
base supported liner which has horizontal restraints
3.1.4
sectional liner
liner which is supported vertically at a number of elevations
3.1.5
liner support
load bearing component which supports the liner
3.1.6
duct entry
part of the liner which introduces the flue gases into the liner
3.1.7
thermal gradient
temperature difference between outer and inner wall surface related to the thickness of the wall
3.1.8
thermal shock
effect on the liner of rapid changes in flue gas temperature, giving stresses. This can typically occur due to
uncontrolled shutdowns, a fire or sudden by-pass of an energy conservation or flue gas desulphurisation unit
3.1.9
compensator
any systems which allows the movement of the joint in any direction maintaining its gas tightness
3.2 Symbols
The main symbols used in this document are given in Table 1.
Table 1 — Main symbols
Symbol Denomination Unit
Safety factor:
partial safety factor -
γ
Material properties:
f strength N/mm
E
modulus of elasticity N/mm
σ stress
N/mm
-1
α coefficient of thermal expansion
T K
Actions:
T thermal effects -
G permanent actions -
W wind actions -
a acceleration m/s
Dimensions:
d diameter m
h height m
t wall thickness m
Subscripts:
c compression -
t tensile -
y yield -
k characteristic -
M material -
4 Material
4.1 General
The choice of material will depend upon the service required.
4.2 Brickwork
4.2.1 General
The type of brickwork used is largely determined by the resistance to chemical attack of the bricks and
mortars. In addition, when thermal shocks are expected, brick types will be selected on the basis of their
resistance to spalling and other mechanical damage caused by the same.
Brickwork covered by this document consists of brick types in accordance with
EN 13084-5:2005, 5.1 and mortar types in accordance with EN 13084-5:2005, 5.2
4.2.2 Thermal effects
According to the requirements as specified in EN 13084-1:2000, 5.2.3.4 the temperature effect on brickwork
shall be considered particularly with regard to:
limit temperature of the various components;
thermal gradients through the brickwork components in steady and transient conditions;
uniform temperature;
expansion;
thermal shock.
Calculations based on the maximum temperature of flue gas and the maximum expected ambient temperature
shall show that all the materials are operating below their allowable temperatures.
Thermal gradients, if not limited, could cause cracks in liners especially in those made of bricks type BT1, BT2
and BT3.
Thermal shock can cause spalling and cracks on bricks type BT1, BT2 and BT3. It normally causes only
shallow cracks but the thermal gradient may cause these to grow.
4.2.3 Classification and chemical attack
4.2.3.1 General
Depending on the degree of chemical attack given in EN 13084-1:2000, Table 3 the following brickwork
classes may be used for the construction of chimney liners:
brickwork class A: resistant to "very high chemical attack";
brickwork class B: resistant to "high chemical attack";
brickwork class C: resistant to "medium chemical attack";
brickwork class D: resistant to "low chemical attack";
brickwork class E: not subject to "chemical attack".
Mortar type MT3 based on Portland cement may be used only for brickwork classes D and E.
NOTE For all brickwork classes in the presence of alkalis with temperatures above 680 °C, bricks with a low true
porosity (10 % maximum) are recommended.
4.2.3.2 Brickwork class A: resistant to "very high chemical attack"
This will normally consist of:
bricks type BT1;
mortar type MT1 (in the case of very high chemical attack due only to acids: mortar type MT2).
If abnormal temperature deviations are expected the limit in service temperature of mortars type MT1 shall be
taken into account.
Brickwork class A using mortar type MT1 can also withstand alkaline condensates.
4.2.3.3 Brickwork class B: resistant to "high chemical attack"
This will normally consist of:
bricks type BT2;
mortar type MT2.
The use of mortar type MT2 allows its use up to 1000 °C; if thermal shocks are expected the resistance to
thermal cycling of the bricks will be a factor of major importance.
Brickwork class B is not resistant to alkaline condensates.
4.2.3.4 Brickwork class C: resistant to "medium chemical attack"
This will normally consist of:
bricks type BT3;
mortar type MT2.
The use of mortar type MT2 allows its use up to 1000 °C; if thermal shocks are expected the resistance to
thermal cycling of the bricks will be a factor of major importance.
Brickwork class C is not resistant to alkaline condensates.
4.2.3.5 Brickwork class D: resistant to "low chemical attack"
This will normally consist of:
bricks type BT4;
mortar type MT3.
4.2.3.6 Brickwork class E: not subjected to chemical attack
This will normally consist of:
bricks type BT4 or BT5;
mortar type MT3.
Brickwork class E may be used in liners that are always operating safely above the dew point.
Bricks type B5 may only be used provided that mechanical actions such as erosion or abrasion are not
expected.
4.3 Insulation
Insulation may be used to reduce the thermal gradient in the liner as well as in the windshield and to reduce
the heat loss of the flue gases.
The following types of insulating materials are widely available for the purpose:
insulating bricks;
mineral wool blankets;
cellular glass blocks;
vermiculite/perlite preformed blocks;
calcium silicate blocks;
glass wool blankets;
ceramic fibre lancets.
Stability of insulation shall be ensured even in the case of vibrations due to possible pulsation of flue gas
pressure.
5 General design requirements
5.1 General
A gas tight floor shall be provided no more than 1,0 m from the bottom of the lowest duct entry.
Adequate means shall be provided to drain acid condensate to a safe location.
5.2 Minimum wall thickness
For the determination of the minimum wall thickness of the liner see Table 2.
Table 2 — Minimum wall thickness for brick liners
1 2 3 4
Internal diameter, d, of
Minimum wall thickness, in mm, for
liner
shaped bricks with lateral shaped bricks with
bricks without tongue and
in m
tongue and groove continuous tongue
groove
and groove
1 0 < d ≤ 4,0 115 100 64
2 115 100 80
4,0 < d ≤ 6,0
3 115 100 100
6,0 < d ≤ 8,0
4 8,0 < d ≤ 10,0 — 120 120
5 — 140 140
10,0 < d ≤ 12,0
5.3 Liner supports
Brick liner supports shall be designed with adequate rigidity to avoid imposing unacceptable non-uniform
support reactions on the liner. In addition, in the case of multiflue chimneys, the deformation of the supporting
platforms shall be such that the required clearance between the top of the liner and the upper platform is
respected. Supports comprising segmental beams, supported by discrete corbels projecting from the
windshield, shall be provided with torsional continuity by in-situ reinforced concrete joints or other means.
5.4 Openings
In order to limit the effects of differential temperatures around the circumference of the liner, openings
introducing gases at different temperatures should be so arranged that a good mixing of the separate gas
streams is ensured. They should be positioned at elevations as near to each other as possible in order to
increase mixing between gas streams and reduce temperature differences which can otherwise cause
additional stresses in the brickwork.
5.5 Ventilation
Brick liners are normally used when flue gas pressure is lower than the ambient pressure outside the
brickwork at the same elevation. Positive pressure excursions of limited duration are permitted, but these
should be taken into account in assessing the chemical load.
If the gas flow calculations show that significant operating periods are expected with flue gas pressure higher
than the pressure in the space between liner and windshield, pressurisation of the space – by the use of fans
– and the provision of compensators are required.
Where access is required into the space between liner and windshield during operation of a liner, ventilation
shall be sufficient to ensure that no flue gas leaks through the liner. The ventilation system shall comply with
the requirements of EN 13084-1:2000, 4.5.
Air ventilation can also be used to cool and avoid significant thermal stresses within the liner supports.
5.6 Protective coatings
Concrete surfaces inside the windshield may be protected by a suitable chemical resistant coating or
membrane, whose viability and long term integrity has been demonstrated in wet and dry conditions of
exposure to flue gas at the anticipated operating temperatures.
An acid resistant coating shall be applied to all parts of the support system that are not easily accessible for
regular inspection and maintenance. In addition, an acid resistant membrane shall be provided between the
support and the supported brickwork. This membrane may be of lead or a chemical resistant coating.
In the case of an accessible space the interior surface of the windshield requires protection particularly if
significant periods of operation characterised by flue gas positive pressure are expected.
Horizontal surfaces of structures for inspection or support (slabs, beams etc.) shall be provided with a
condensates draining system when the formation of aggressive condensate is expected.
5.7 Accessories
5.7.1 Joints
At joints between liner sections, the liner shall have at least 30 mm clearance under operating conditions in
every direction between it and the other liner or its support.
NOTE In the cases of "very high" and "high" chemical attack the brickwork tends in time to show an irreversible
expansion due to a chemical reaction between the brickwork and the acid condensate. This irreversible expansion
can be as much as 0,15 %.
The joints cause a loss of gas tightness of the liner and, to prevent collection of debris and condensates, joints
can be filled by blankets, ropes and similar materials whose properties will be chosen according to the
operating gas conditions.
5.7.2 Compensators
A compensator should be a suitable system for sealing the structural joints between brick liner sections to
improve the gas tightness of the liner (see Annex C).
5.7.3 Ducts and fans
The vibrations of ducts or fans outside the chimney can cause vibrations of the liner. Provisions shall be made
to prevent transmission of such vibrations.
6 Structural design
6.1 Actions
6.1.1 General
Actions to be considered are given in EN 13084-1. In addition the following specifications apply.
6.1.2 Wind actions
As the liner is protected from the wind by the windshield, the only effect of wind in the case of sectional liners
is that induced by the dynamic response of the concrete windshield, i.e. the stress in the liner sections is
assumed to be caused only by the acceleration of the windshield at the liner support elevation.
NOTE 1 The concrete windshield responds dynamically only to that part of the fluctuating wind gusts which
represents their dynamic effect (as opposed to that part representing background turbulence). Also, higher modes of
the concrete windshield's response to these gusts are unimportant. Thus only the loads induced by the windshield's
fundamental response need to be considered. Similar considerations apply to those discussed in Annex D, i.e. there
is no magnification due to resonance, when these loads are considered. For typical chimneys, the resulting peak
acceleration in the liner amounts to less than 0,05 g and is negligible.
In case of sectional liners whose height is much smaller than the height of the windshield, no resonance due
to wind excitation will occur and therefore wind loading may be neglected except for the top protruding section
above the windshield, if any.
NOTE 2 It is recommended that the protruding section be protected by a separate concentric concrete or brickwork
windshield.
6.1.3 Seismic actions
Seismic actions cause stresses in the liner sections due to the acceleration of the windshield at the liner
support elevation. The determination of the dynamic effects is given in Annex D.
6.1.4 Thermal effects
Thermal effects in the brick liner shall be considered in the following cases of heat flow causing thermal
gradients across the liner:
steady heat flow;
transient heat flow.
Thermal stresses for both the steady heatflow and the transient heat flow can be calculated according to
Annex F.
The maximum thermal effect for steady heat flow is caused by the maximum expected operating temperature
and the minimum ambient design temperature.
The maximum thermal effect for transient heat flow shall be calculated by assuming an increased temperature
of 1,1 T or (T + 30 K) whichever is the highest, where T is the maximum temperature under the expected
0 0 0
operating conditions.When a single brick liner carries flue gases from two or more ducts at different
temperatures, an additional thermal effect is caused in the bottom section(s). In such cases baffle walls should
not be used as they interfere with the mixing of the flue gases.
NOTE Generally speaking turbulence at duct entries, although causing local pressure losses, is beneficial as it
increases mixing between gas streams and thus reduces the temperature differences which would otherwise cause
increased stresses in the brickwork.
6.1.5 Internal pressure and explosions
An occasional positive pressure during normal operation will not normally cause tensile stresses of any
importance in the liner. Nevertheless, if positive pressure is anticipated (see EN 13084-1:2000, 5.2.3.3 and
5.2.4.2), the pressure should be estimated and brickwork stresses checked.
If pulsation of flue gas pressure is expected the possibility of resonance should be investigated.
6.2 Resistances
With reference to the brickwork composition defined in 4.2.3, the characteristic values of mechanical
properties shall be assumed according to Table 3 unless panel tests in accordance with EN 1052-1 and
EN 1052-2 are available.
Table 3 — Characteristic values of mechanical properties of brickwork
Brickwork class Compressive Flexural Modulus of Poisson's Coefficient of
tensile
strength f elasticity E thermal
ratio υυυυ
k
a
strength f
x1k
expansion αααα
T
in N/mm in N/mm
-1
in N/mm
in K
b
c
b, c
A 25 (15) 3 (2)
c
1,5 x 10
B 15 2
-6
c
0,23
C 15 2
6 x 10
D 10 0,4
E 6,5 0,4
a
Parallel to the bed joints
b
If mortar type MT2 in used.
c
May also be applied to the tensile strength f perpendicular to the bed joints if bricks with continuous tongue and grove are
x2k
used.
6.3 Verification
6.3.1 Ultimate limit state
6.3.1.1 General
The stability of a brick liner has to be verified if the section height h exceeds 20 m, or the thickness of the liner
wall is less than 100 mm or the slenderness, h /d, is greater than 10, where slenderness is the ratio of height
ℓ
to the smallest outside diameter.
The ultimate load bearing capacity of the liner shall be compared with the calculated effects of the actions at
ultimate limit state. These actions include: earthquake or wind (including the effects of vibrations of the
windshield, in each case, if significant), permanent actions, thermal effects and internal pressure.
For the design criteria in presence of openings see Annex B.
6.3.1.2 Combination of actions and partial safety factors for actions
6.3.1.2.1 Verification in horizontal sections
The design value of the effects of actions in the horizontal sections of the liner have to be calculated from the
following combinations of actions as given in equations (1) and (2) and Table 4.
For persistent design situations:
E = γ × G + γ × Q + γ ×ψ × Q (1)
d G k Q1 k1 ∑ Qi 0i ki
if1
For accidental design situations (seismic actions):
(2)
E = G + A
dE k Ed
where
E is the design value of the effect of actions (basic combination);
d
E is the design value of the effect of actions from earthquake combination (seismic actions);
dE
γ is the partial safety factor for permanent actions;
G
γ is the partial safety factor for variable actions;
Q
A is the design value of seismic actions;
Ed
G is the characteristic value of permanent actions;
k
Q is the characteristic value of the leading variable action 1;
k1
Q is the characteristic value of the accompanying variable action i;
ki
ψ is the combination factor.
0i
a
Table 4 — Combination of actions for persistent design situations
G
Combination Q Q
k1 k2
k
1 G W T
st
2 G T —
st
3 G T —
tr
a
G Permanent action;
W Wind action;
T Thermal effects due to the maximum possible thermal gradient
st
at steady conditions;
T Thermal effects due to the maximum possible thermal gradient
tr
at transient conditions.
NOTE The values of γ , γ and ψ in the ultimate limit state for use in a Country may be found in its National Annex.
G Qi 0i
The recommended values for γ and γ are given in Table 5N. The recommended value for ψ = ψ is 0,6.
G Qi 0i 02
Table 5 N – Partial safety factors γγG and γγQi for actions
γγ γγ
Action G W T T
st tr
a
γ = 1,0 γ = 1,5 γ = 1,3 γ = 1,3
G Qi Qi Qi
a
For sections outside windshield γ = 1,6
Qi
6.3.1.2.2 Verification in vertical sections
For the determination of the effects of actions in the vertical sections of the liner, the only action to be
considered is the internal pressure, applying a partial safety factor γ .
Q1
NOTE The value of γ in the ultimate limit state for use in a Country may be found in its National Annex. The
Q1
recommended value for γ is 1,3.
Q1
In the cases of internal explosion or significant positive pressure deviation, the brickwork shall be assumed to
be cracked and steel banding or prestressing are required (see Annex E).
In circular cross sections internal pressure causes only axial forces whereas in non-circular sections bending
moments have also to be considered.
If the negative pressure in the flue gas is very high, the bending moments due to deviation of the liner from a
true circle can cause cracks and even collapse. A check on the safety should be performed on a non-circular
liner or a circular liner whose shape falls outside the tolerances listed in 7.2.
6.3.1.3 Partial safety factors for materials
Partial safety factors γ for brickwork shall be applied in the ultimate limit state.
M
NOTE The values of γ in the ultimate limit state for use in a Country may be found in its National Annex. The
M
recommended values for γ are given in Table 6N.
M
Table 6 N — Partial safety factors γγM for brickwork
γγ
Characteristic γγ
γγM
compression 3,0
tension 1,3
6.3.2 Serviceability limit state
6.3.2.1 Deformation
Deformation due to thermal effects shall be taken into account by specifying clearances at maximum
operating temperature. Deformation due to chemical effects cannot be exactly predicted and shall be avoided
by careful choice of materials.
Deformations due to mechanical loading and deflection of permanent support structures need to be
considered under serviceability loading conditions.
The calculation of deflections of the support structure shall take account of the possibility of cracking.
6.3.2.2 Cracking
Vertical cracking of the brickwork can be caused by thermal gradient across the wall thickness, thermal
shocks, positive pressure deviations and bending of non-circular liners under internal pressure.
To limit the crack width it has to be verified that the flexural tensile stresses do not exceed the flexural tensile
strength of the brickwork given in Table 3.
The following actions shall be considered independently for the check of flexural tensile stresses under
serviceability conditions:
P maximum positive pressure deviation;
T maximum thermal gradient;
M bending due to internal pressure in case of non-circular liners.
6.3.2.3 Partial safety factors
Partial safety factors for actions, γ , as well as for material, γ , shall be applied in the serviceability limit state.
F M
NOTE The values of γ and γ in the serviceability limit state for use in a Country may be found in its National
F M
Annex. The recommended value for γ as well as for γ is 1,0.
F M
6.3.3 Stress calculations in the ultimate limit state
6.3.3.1 General
Compressive and tensile stresses shall be computed for the actions or combinations of actions given in
6.3.1.2.
The design values of the resulting stresses shall not exceed the design values of the resistances derived by
dividing the characteristic strengths given in 6.2 by the appropriate partial safety factor γ .
M
Thermal stresses may be determined according to Annex F.
6.3.3.2 Stresses in horizontal sections
For brickwork classes A, B and C using bricks with continuous tongue and groove stresses shall be calculated
assuming that horizontal joints are capable of transmitting tensile stresses not exceeding the design values
specified in 6.3.3.1. If the resulting tensile stresses exceed the above limits, the stresses shall be recalculated,
assuming the joints incapable of transmitting tensile stresses (i. e. they open under tension). In this case the
length of open joints shall not exceed half of the circumference.
For brickwork classes A, B and C using bricks without continuous tongue and groove as well as for classes D
and E stresses shall be calculated assuming that horizontal joints are incapable of transmitting tensile
stresses (i.e. they open under tension). The length of open joints shall not exceed half of the circumference.
Local stresses from thermal effects shall be added to the global stresses acting on the whole section. Special
consideration shall be given to the stresses in the horizontal joints near the top of the liner, where thermal
stresses are increased by end effects and mortar adhesion is reduced.
For the determination of thermal stresses, the modulus of elasticity may be taken from Table 3 unless values,
obtained from the test in accordance with EN 1052-2 are available.
6.3.3.3 Stresses in vertical sections
Stresses shall be calculated for the actions given in 6.3.1.2.2 assuming that vertical sections are capable of
transmitting tensile stresses not exceeding the design values specified in 6.3.3.1.
If the resulting tensile stresses exceed the above limits, the stresses shall be recalculated, assuming the joints
incapable of transmitting tensile stresses (i. e. they open under tension). In this case the length of open joints
shall not exceed half of the wall thickness.
6.3.4 Elastic stability
Instability of a liner can be caused by overall buckling or by local buckling due to self
...
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