EN 1991-1-2:2024
(Main)Eurocode 1 - Actions on structures – Part 1-2: Actions on structures exposed to fire
Eurocode 1 - Actions on structures – Part 1-2: Actions on structures exposed to fire
1.1 Scope of EN 1991 1 2
(1) The methods given in this Eurocode are applicable to buildings and civil engineering works, with a fire load related to the building and its occupancy.
(2) EN 1991 1 2 deals with thermal and mechanical actions on structures exposed to fire. It is intended to be used in conjunction with the fire design Parts of EN 1992 to EN 1996 and EN 1999 which give rules for designing structures for fire resistance.
(3) EN 1991 1 2 contains thermal actions either nominal or physically based. More data and models for physically based thermal actions are given in annexes.
(4) EN 1991 1 2 does not cover the assessment of the damage of a structure after a fire.
(5) EN 1991 1 2 does not cover supplementary requirements concerning, for example:
- the possible installation and maintenance of sprinkler systems;
- conditions on occupancy of building or fire compartment;
- the use of approved insulation and coating materials, including their maintenance.
1.2 Assumptions
(1) In addition to the general assumptions of EN 1990 the following assumptions apply:
- any active and passive fire protection systems taken into account in the design will be adequately maintained;
- the choice of the relevant design fire scenario is made by appropriate qualified and experienced personnel, or is given by the relevant national regulation.
Eurocode 1 - Einwirkungen auf Tragwerke - Teil 1-2: Allgemeine Einwirkungen - Brandeinwirkungen auf Tragwerke
1.1 Anwendungsbereich von FprEN 1991 1 2
(1) Die in diesem Eurocode angegebenen Verfahren sind auf Hoch- und Ingenieurbauten mit Brandlasten entsprechend der Gebäudeart und nutzung anwendbar.
(2) FprEN 1991 1 2 behandelt die thermischen und mechanischen Einwirkungen auf Tragwerke unter Brandbeanspruchung. FprEN 1991 1 2 ist vorgesehen zur Anwendung in Zusammenhang mit den Brandschutzteilen von EN 1992 bis EN 1996 sowie EN 1999, welche die Regeln für die Bemessung von Tragwerken auf Feuerwiderstand enthalten.
(3) FprEN 1991 1 2 enthält thermische Einwirkungen, die entweder nominell oder physikalisch basiert sind. Weitere Daten und Modelle für physikalisch basierte thermische Einwirkungen sind in Anhängen angegeben.
(4) FprEN 1991 1 2 behandelt nicht die Schadensbewertung eines Tragwerks nach einem Brand.
(5) FprEN 1991 1 2 behandelt keine ergänzenden Anforderungen beispielsweise bezüglich:
— des möglichen Einbaus und der Instandhaltung von Sprinkleranlagen;
— der Bedingungen für die Bewohnbarkeit von Gebäude- oder Brandabschnitten;
— der Verwendung von zugelassenen Dämm- und Beschichtungsstoffen, einschließlich ihrer Instandhaltung.
1.2 Voraussetzungen
(1) Zusätzlich zu den allgemeinen Voraussetzungen in EN 1990 gelten die folgenden Voraussetzungen:
— die Wahl des maßgebenden Bemessungsbrandszenarios wird durch entsprechend qualifiziertes und erfahrenes Personal getroffen oder durch die maßgebende nationale Vorschrift vorgegeben;
— jede bei der Bemessung berücksichtigte Brandschutzmaßnahme wird ausreichend gewartet.
Eurocode 1 - Actions sur les structures - Partie 1-2: Actions sur les structures exposées au feu
1.1 Domaine d’application du prEN 1991 1 2
(1) Les méthodes indiquées dans le présent Eurocode sont applicables aux bâtiments et aux ouvrages de génie civil, en prenant en compte une charge calorifique liée au bâtiment et à son occupation.
(2) Le prEN 1991 1 2 traite des actions thermiques et mécaniques sur les structures exposées au feu. Il est destiné à être utilisé en association avec les parties relatives au calcul au feu des EN 1992 à EN 1996 et de l’EN 1999, qui fixent les règles de calcul de résistance au feu des structures.
(3) Le prEN 1991 1 2 comporte les actions thermiques qui sont soit nominales, soit physiquement fondées. Les annexes présentent des données supplémentaires et des modèles pour des actions thermiques physiquement fondées.
(4) Le prEN 1991 1 2 ne traite pas de l’évaluation des dommages subis par une structure après un incendie.
(5) Le prEN 1991 1 2 ne traite pas des exigences supplémentaires concernant par exemple :
- l’installation et la maintenance éventuelles de systèmes d’extinction ;
- les conditions d’occupation du bâtiment ou du compartiment ;
- l’utilisation de matériaux isolants et de revêtement agréés, y compris leur maintenance.
1.2 Hypothèses
(1) Outre les hypothèses générales du prEN 1990, les hypothèses suivantes s’appliquent :
- tout système de protection incendie actif ou passif pris en compte dans le calcul fait l’objet d’une maintenance adéquate ;
- le choix du scénario de feu de calcul pertinent est fait par un personnel possédant une qualification et une expérience appropriées, ou est indiqué par la réglementation nationale concernée.
Evrokod 1 - Vplivi na konstrukcije - 1-2. del: Vplivi požara na konstrukcije
1.1 Področje uporabe standarda EN 1991-1-2
(1) Metode v tem Evrokodu se uporabljajo za stavbe in gradbene inženirske objekte, pri čemer je požarna obremenitev povezana s stavbo in njeno zasedenostjo.
(2) Standard EN 1991-1-2 obravnava toplotne in mehanske vplive požara na konstrukcije. Uporablja se v povezavi z deli standardov EN 1992 do EN 1996, ki obravnavajo požarnoodporno projektiranje, in standardom EN 1999, ki podaja pravila za projektiranje ognjevzdržnih konstrukcij.
(3) Standard EN 1991-1-2 vsebuje nominalne in fizikalne toplotne vplive. Več podatkov in modelov za fizikalne toplotne vplive je podanih v dodatkih.
(4) Standard EN 1991-1-2 ne zajema ocene škode na konstrukciji po požaru.
(5) Standard EN 1991-1-2 ne zajema dodatnih zahtev, na primer v zvezi z naslednjim:
– morebitno namestitvijo in vzdrževanjem sprinklerskih sistemov;
– pogoji o zasedenosti stavbe ali požarnega oddelka;
– uporabo odobrenih izolacijskih in premaznih materialov, vključno z njihovim vzdrževanjem.
1.2 Predpostavke
(1) Poleg splošnih predpostavk iz standarda EN 1990 se uporabljajo tudi naslednje predpostavke:
– vse aktivne in pasivne požarnovarnostne sisteme, ki se upoštevajo pri projektiranju, je treba ustrezno vzdrževati;
– ustrezni projektirni požarni scenarij izbere ustrezno, kvalificirano in izkušeno osebje ali pa je določen v ustreznih nacionalnih predpisih.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 1991-1-2:2024
01-julij-2024
Nadomešča:
SIST EN 1991-1-2:2004
SIST EN 1991-1-2:2004/AC:2013
Evrokod 1 - Vplivi na konstrukcije - 1-2. del: Vplivi požara na konstrukcije
Eurocode 1 - Actions on structures – Part 1-2: Actions on structures exposed to fire
Eurocode 1 - Einwirkungen auf Tragwerke - Teil 1-2: Einwirkungen im Brandfall
Eurocode 1 - Actions sur les structures - Partie 1-2: Actions sur les structures exposées
au feu
Ta slovenski standard je istoveten z: EN 1991-1-2:2024
ICS:
13.220.50 Požarna odpornost Fire-resistance of building
gradbenih materialov in materials and elements
elementov
91.010.30 Tehnični vidiki Technical aspects
SIST EN 1991-1-2:2024 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
SIST EN 1991-1-2:2024
SIST EN 1991-1-2:2024
EN 1991-1-2
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2024
EUROPÄISCHE NORM
ICS 13.220.50; 91.010.30 Supersedes EN 1991-1-2:2002
English Version
Eurocode 1 - Actions on structures - Part 1-2: Actions on
structures exposed to fire
Eurocode 1 - Actions sur les structures - Partie 1-2: Eurocode 1 - Einwirkungen auf Tragwerke - Teil 1-2:
Actions sur les structures exposées au feu Allgemeine Einwirkungen - Brandeinwirkungen auf
Tragwerke
This European Standard was approved by CEN on 1 January 2024.
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
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 1991-1-2:2024 E
worldwide for CEN national Members.
SIST EN 1991-1-2:2024
Contents
European foreword . 5
Introduction . 6
1 Scope . 10
1.1 Scope of EN 1991-1-2 . 10
1.2 Assumptions . 10
2 Normative references . 10
3 Terms, definitions and symbols . 11
3.1 Terms and definitions . 11
3.1.1 Common terms used in Eurocode Fire parts . 11
3.1.2 Special terms relating to design in general . 13
3.1.3 Terms relating to thermal actions . 13
3.1.4 Terms relating to heat transfer analysis . 15
3.2 Symbols and abbreviations . 16
3.2.1 Latin upper case letters . 16
3.2.2 Latin lower case letters . 18
3.2.3 Greek upper case letters . 19
3.2.4 Greek lower case letters . 20
4 Structural fire design procedure . 21
4.1 General. 21
4.2 Design fire scenario . 21
4.3 Design fire . 21
4.4 Temperature analysis of members . 21
4.5 Mechanical analysis of members . 22
5 Thermal actions for temperature analysis . 23
5.1 Heat flux . 23
5.2 Nominal fire curves . 24
5.2.1 Standard fire curve . 24
5.2.2 External fire curve . 24
5.2.3 Hydrocarbon fire curve . 24
5.3 Physically based fire models . 25
5.3.1 Simplified fire models . 25
5.3.2 Advanced fire models . 25
6 Mechanical actions for structural analysis . 26
6.1 General. 26
6.2 Simultaneity of actions . 26
6.2.1 Actions from normal temperature design . 26
6.2.2 Additional actions . 27
6.3 Combination rules for actions . 27
6.3.1 General rule . 27
6.3.2 Simplified rules. 27
6.3.3 Load level . 29
Annex A (informative) Parametric fire curves . 30
A.1 Use of this annex . 30
A.2 Scope and field of application . 30
A.3 Fire curves in the heating phase . 30
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A.4 Fire curves in the cooling phase . 32
Annex B (informative) Thermal actions for external members — Simplified calculation
method . 33
B.1 Use of this annex . 33
B.2 Scope and field of application . 33
B.3 Conditions of use . 33
B.4 Effects of wind . 34
B.4.1 Mode of ventilation . 34
B.4.2 Flame deflection by wind . 34
B.5 Characteristics of fire and flames . 35
B.5.1 No forced draught . 35
B.5.2 Forced draught . 38
B.6 Overall configuration factors . 41
Annex C (informative) Localized fires . 42
C.1 Use of this annex . 42
C.2 Scope and field of application . 42
C.3 Virtual solid flame . 42
C.3.1 Shape of the virtual solid flame . 42
C.3.2 Temperature of the virtual solid flame . 43
C.3.3 Virtual solid flame position and extension . 44
C.3.4 Net heat flux . 48
Annex D (informative) Advanced fire models . 49
D.1 Use of this annex . 49
D.2 Scope and field of application . 49
D.3 One-zone models. 49
D.4 Two-zone models . 50
D.5 Computational fluid dynamics models . 50
Annex E (informative) Fire load densities, fire growth rates and rate of heat releases . 51
E.1 Use of this annex . 51
E.2 Scope and field of application . 51
E.3 Design value of fire load density . 51
E.4 Determination of fire load densities . 54
E.4.1 General . 54
E.4.2 Definitions . 54
E.4.3 Protected fire loads . 55
E.4.4 Net calorific values . 55
E.4.5 Fire load classification of occupancies . 57
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E.4.6 Individual assessment of fire load densities . 58
E.5 Combustion behaviour . 58
E.6 Rate of heat release Q . 58
Annex F (informative) Equivalent time of fire exposure . 61
F.1 Use of this annex . 61
F.2 Scope and field of application . 61
F.3 Equivalent time of standard fire exposure . 61
Annex G (informative) Configuration factor . 63
G.1 Use of this annex . 63
G.2 Scope and field of application . 63
G.3 General. 63
G.4 Shadow effects . 64
G.5 External members . 64
G.6 Virtual solid flame . 67
Annex H (informative) Thermal actions for structural fire loads of timber structures . 71
H.1 Use of this annex . 71
H.2 Scope and field of application . 71
H.3 General. 71
H.4 Structural fire load by the timber members . 72
Bibliography . 75
SIST EN 1991-1-2:2024
European foreword
This document (EN 1991-1-2:2024) has been prepared by Technical Committee CEN/TC 250 “Structural
Eurocodes”, the secretariat of which is held by BSI. CEN/TC 250 is responsible for all Structural
Eurocodes and has been assigned responsibility for structural and geotechnical design matters by CEN.
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 September 2027, and conflicting national standards shall
be withdrawn at the latest by March 2028.
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 1991-1-2:2002.
The first generation of EN Eurocodes was published between 2002 and 2007. This document forms part
of the second generation of the Eurocodes, which have been prepared under Mandate M/515 issued to
CEN by the European Commission and the European Free Trade Association.
The Eurocodes have been drafted to be used in conjunction with relevant execution, material, product
and test standards, and to identify requirements for execution, materials, products and testing that are
relied upon by the Eurocodes.
The Eurocodes recognize the responsibility of each Member State and have safeguarded their right to
determine values related to regulatory safety matters at national level through the use of National
Annexes.
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 organisations 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.
SIST EN 1991-1-2:2024
Introduction
0.1 Introduction to the Eurocodes
The structural Eurocodes comprise the following standards generally consisting of a number of Parts:
— EN 1990, Eurocode — Basis of structural and Geotechnical design
— EN 1991, Eurocode 1 — 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 structure
— 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 structures for earthquake resistance
— EN 1999, Eurocode 9 — Design of aluminium structures
— New Eurocodes under development, e.g. Eurocode for design of structural glass
The Eurocodes are intended for use by designers, clients, manufacturers, constructors, relevant
authorities (in exercising their duties in accordance with national or international regulations),
educators, software developers, and committees drafting standards for related product, testing and
execution standards.
NOTE Some aspects of design are most appropriately specified by relevant authorities or, where not specified,
can be agreed on a project-specific basis between relevant parties such as designers and clients. The Eurocodes
identify such aspects making explicit reference to relevant authorities and relevant parties.
0.2 Introduction to EN 1991
EN 1991 (all parts) specifies actions for the structural design of buildings, bridges and other civil
engineering works, or parts thereof, including temporary structures, in conjunction with EN 1990 and
the other Eurocodes.
EN 1991 does not cover the specific requirements of actions for seismic design. Provisions related to such
requirements are given in EN 1998 (all parts), which complement and are consistent with EN 1991.
EN 1991 is also applicable to existing structures for their:
— structural assessment,
— strengthening or repair,
— change of use.
NOTE 1 In these cases, additional or amended provisions can be necessary.
EN 1991 is also applicable for the design of structures where materials or actions outside the scope of the
other Eurocodes are involved.
SIST EN 1991-1-2:2024
NOTE 2 In this case, additional or amended provisions can be necessary.
EN 1991 is subdivided in various parts:
EN 1991-1-1, Eurocode 1 — Actions on structures — Part 1-1: Specific weight of materials, self-weight of
construction works and imposed loads for buildings
EN 1991-1-2, Eurocode 1 — Actions on structures — Part 1-2: Actions on structures exposed to fire
EN 1991-1-3, Eurocode 1 — Actions on structures — Part 1-3: Snow Loads
EN 1991-1-4, Eurocode 1 — Actions on structures — Part 1-4: Wind Actions
EN 1991-1-5, Eurocode 1 — Actions on structures — Part 1-5: Thermal Actions
EN 1991-1-6, Eurocode 1 — Actions on structures — Part 1-6: Actions during execution
EN 1991-1-7, Eurocode 1 — Actions on structures — Part 1-7: Accidental actions
EN 1991-1-8, Eurocode 1 — Actions on structures — Part 1-8: Actions from waves and currents on coastal
structures
EN 1991-1-9, Eurocode 1 — Actions on structures — Part 1-9: Atmospheric icing
EN 1991-2, Eurocode 1 — Actions on structures — Part 2: Traffic loads on bridges and other civil
engineering works
EN 1991-3, Eurocode 1 — Actions on structures — Part 3: Actions induced by cranes and machines
EN 1991-4, Eurocode 1 — Actions on structures — Part 4: Silos and tanks
0.3 Introduction to EN 1991-1-2
EN 1991-1-2 describes the thermal and mechanical actions for the structural design of buildings exposed
to fire, including the following safety requirements and design procedures.
EN 1991-1-2 is intended to be used with EN 1990, the other Parts of EN 1991 and EN 1992 to EN 1999
for the design of structures.
0.3.1 Safety requirements
The general objectives are to limit risks with respect to the individual and society, neighbouring property,
and where required, environment or directly exposed property, in the case of fire.
Construction Products Regulation (EU) No 305/2011 gives the following requirement for the limitation
of the consequence in case of fire:
“The construction works must be designed and built in such a way, that in the event of an outbreak of fire
— the load bearing capacity of the construction can be assumed for a specified period of time,
— the generation and spread of fire and smoke within the works are limited,
— the spread of fire to neighbouring construction works is limited,
— the occupants can leave the works or can be rescued by other means,
— the safety of rescue teams is taken into consideration”.
1)
According to the Interpretative Document N°2 “Safety in Case of Fire” the essential requirement may be
observed by following various possibilities for fire safety strategies prevailing in the Member States like
1) See 2.2, 3.2(4) and 4.2.3.3 of ID N°2.
SIST EN 1991-1-2:2024
conventional fire scenarios (nominal fires) or “natural” (physically based) fire scenarios, including
passive and/or active fire protection measures.
Required functions and levels of performance can be specified either in terms of nominal (standard) fire
resistance rating, generally given in national fire regulations or, where allowed by national fire
regulations, by referring to fire safety engineering for assessing passive and active measures.
The fire parts of Structural Eurocodes deal with specific aspects of passive fire protection in terms of
designing structures and parts thereof for adequate load bearing resistance and for limiting fire spread
as relevant.
Numerical values for partial factors and other reliability elements are given to provide an acceptable level
of reliability. They have been selected assuming that an appropriate level of workmanship and of quality
management applies.
0.3.2 Design procedures
A full analytical procedure for structural fire design would take into account the behaviour of the
structural system at elevated temperatures, the potential heat exposure and the beneficial effects of
active and passive fire protection systems, together with the uncertainties associated with these three
features and the importance of the structure (consequences of failure).
At the present time, it is possible to undertake a procedure for determining adequate performance which
incorporates some, if not all, of the above parameters and to demonstrate that the structure, or its
components, will give adequate performance in a real building fire. However, where the procedure is
based on a nominal (standard) fire, the classification system, which calls for specific periods of fire
resistance, takes into account (though not explicitly) the features and uncertainties described above.
Figure 1 illustrates the two design procedures provided by EN 1991-1-2, i.e. the prescriptive approach
and the performance-based approach. The prescriptive approach uses nominal (standard) fires to
generate thermal actions. The performance-based approach, using fire safety engineering, refers to
thermal actions based on physical and chemical parameters.
Figure 1 — Alternative design procedures
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0.4 Verbal forms used in the Eurocodes
The verb “shall” expresses a requirement strictly to be followed and from which no deviation is permitted
in order to comply with the Eurocodes.
The verb “should” expresses a highly recommended choice or course of action. Subject to national
regulation and/or any relevant contractual provisions, alternative approaches could be used/adopted
where technically justified.
The verb “may” expresses a course of action permissible within the limits of the Eurocodes.
The verb “can” expresses possibility and capability; it is used for statements of fact and clarification of
concepts.
0.5 National Annex for EN 1991-1-2
National choice is allowed in this document where explicitly stated within notes. National choice includes
the selection of values for Nationally Determined Parameters (NDPs).
The national standard implementing EN 1991-1-2 can have a National Annex containing all national
choices to be used for the design of buildings and civil engineering works to be constructed in the relevant
country.
When no national choice is given, the default choice given in this document is to be used.
When no national choice is made and no default is given in this document, the choice can be specified by
a relevant authority or, where not specified, agreed for a specific project by appropriate parties.
National choice is allowed in EN 1991-1-2 through notes to the following clauses:
4.4(4) NOTE 6.2.2(2) 6.3.1(2) H.3(4)
National choice is allowed in EN 1991-1-2 on the application of the following informative annexes:
Annex A Annex B Annex C Annex D
Annex E Annex F Annex G Annex H
The National Annex can contain, directly or by reference, non-contradictory complementary information
for ease of implementation, provided it does not alter any provisions of the Eurocodes.
SIST EN 1991-1-2:2024
1 Scope
1.1 Scope of EN 1991-1-2
(1) The methods given in this Eurocode are applicable to buildings and civil engineering works, with a
fire load related to the building and its occupancy.
(2) EN 1991-1-2 deals with thermal and mechanical actions on structures exposed to fire. It is intended
to be used in conjunction with the fire design Parts of EN 1992 to EN 1996 and EN 1999 which give rules
for designing structures for fire resistance.
(3) EN 1991-1-2 contains thermal actions either nominal or physically based. More data and models
for physically based thermal actions are given in annexes.
(4) EN 1991-1-2 does not cover the assessment of the damage of a structure after a fire.
(5) EN 1991-1-2 does not cover supplementary requirements concerning, for example:
— the possible installation and maintenance of sprinkler systems;
— conditions on occupancy of building or fire compartment;
— the use of approved insulation and coating materials, including their maintenance.
1.2 Assumptions
(1) In addition to the general assumptions of EN 1990 the following assumptions apply:
— the choice of the relevant design fire scenario is made by appropriate qualified and experienced
personnel, or is given by the relevant national regulation;
— any fire protection measure taken into account in the design will be adequately maintained.
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.
NOTE See the Bibliography for a list of other documents cited that are not normative references, including
those referenced as recommendations (i.e. in ‘should’ clauses), permissions (‘may’ clauses), possibilities ('can'
clauses), and in notes.
EN 1990:2023, Eurocode — Basis of structural and Geotechnical design
EN 1992 (all parts), Eurocode 2 — Design of concrete structures
EN 1996 (all parts), Eurocode 6 — Design of masonry structures
EN 1999 (all parts), Eurocode 9 — Design of aluminium structures
EN 1993-1-2:2024, Eurocode 3 — Design of steel structures — Part 1-2: Structural fire design
EN 13501-2, Fire classification of construction products and building elements — Part 2: Classification
using data from fire resistance tests, excluding ventilation services
SIST EN 1991-1-2:2024
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 1990 and the following apply.
3.1.1 Common terms used in Eurocode Fire parts
3.1.1.1
equivalent time of fire exposure
time of exposure to the standard fire curve supposed to have the same heating effect as a real fire in the
compartment
3.1.1.2
external member
structural member located outside the building that can be exposed to fire through openings in the
building enclosure
3.1.1.3
compartment, fire compartment
space within a building, extending over one or several floors, which is enclosed by separating elements
such that fire spread beyond the compartment is prevented during the relevant fire exposure
3.1.1.4
fire resistance
ability of a structure, a part of a structure or a member to fulfil its required functions (load bearing
function and/or fire separating function) for a specified load level, for a specified fire exposure and for a
specified period of time
3.1.1.5
fully developed fire
state of full involvement of all combustible surfaces in a fire within a specified space
3.1.1.6
global structural analysis (for fire)
structural analysis of the entire structure, when either the entire structure, or only a part of it, are exposed
to fire
Note 1 to entry: Indirect fire actions are considered throughout the structure.
3.1.1.7
indirect fire actions
internal forces and moments caused by thermal expansion
3.1.1.8
integrity
E
ability of a separating element of building construction, when exposed to fire on one side, to prevent the
passage through it of flames and hot gases and to prevent the occurrence of flames on the unexposed side
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3.1.1.9
insulation
I
ability of a separating element of building construction when exposed to fire on one side, to restrict the
temperature rise of the unexposed face below specified levels
3.1.1.10
load bearing function
R
ability of a structure or a member to sustain specified actions during the relevant fire, according to
defined criteria
3.1.1.11
member
basic part of a structure (such as beam, column, but also assembly such as stud wall, truss) considered as
isolated with appropriate boundary and support conditions
3.1.1.12
member analysis (for fire)
thermal and mechanical analysis of a structural member exposed to fire in which the member is assumed
as isolated, with appropriate support and boundary conditions
Note 1 to entry: Indirect fire actions are not considered, except those resulting from thermal gradients.
3.1.1.13
normal temperature design
ultimate limit state design for ambient temperatures according to Part 1-1 of EN 1992 to EN 1996 or
EN 1999
3.1.1.14
separating function
ability of a separating element to prevent fire spread (e.g. by passage of flames or hot gases — cf.
integrity) or ignition beyond the exposed surface (cf. insulation) during the relevant fire
3.1.1.15
separating element
load bearing or non-load bearing element (e.g. wall) forming part of the enclosure of a fire compartment
3.1.1.16
standard fire resistance
ability of a structure or part of it (usually only members) to fulfil required functions (load-bearing
function and/or separating function), for the exposure to heating according to the standard fire curve for
a specified load combination and for a stated period of time
3.1.1.17
structural members
physically distinguishable part of a structure, e.g. column, beam, plate, foundation
3.1.1.18
temperature analysis
procedure of determining the temperature development in members based on the thermal actions (net
heat flux) and the thermal material properties of the members and of protective surfaces, where relevant
SIST EN 1991-1-2:2024
3.1.1.19
thermal actions
actions on the structure described by the net heat flux to the members
3.1.2 Special terms relating to design in general
3.1.2.1
advanced fire model
design fire based on mass conservation and energy conservation aspects
3.1.2.2
computational fluid dynamics model
fire model able to solve numerically the partial differential equations giving, in all points of the
compartment, the thermo-dynamical and aero-dynamical variables
3.1.2.3
fire wall
separating element that is a wall separating two spaces (e.g. two buildings) that is designed for fire
resistance and structural stability, and may include resistance to horizontal loading such that, in case of
fire and failure of the structure on one side of the wall, fire spread beyond the wall is avoided
3.1.2.4
one-zone model
fire model where homogeneous temperatures of the gas are assumed in the compartment
3.1.2.5
simplified fire model
design fire based on a limited application field of specific physical parameters
3.1.2.6
two-zone model
fire model where different zones are defined in a compartment: the upper layer, the lower layer, the fire
and its plume, the external gas and walls
Note 1 to entry: In the upper and lower layers, uniform temperature of the gas is assumed.
3.1.3 Terms relating to thermal actions
3.1.3.1
combustion factor
factor representing the efficiency of combustion, varying between 1 for complete combustion to 0 for
combustion fully inhibited
3.1.3.2
design fire
quantitative description of assumed fire characteristics within a design fire scenario specified
3.1.3.3
design fire load density
fire load density considered for determining thermal actions in fire design
3.1.3.4
design fire scenario
specific fire scenario on which an analysis will be conducted
SIST EN 1991-1-2:2024
3.1.3.5
external fire curve
nominal fire curve intended for the outside of separating (EI) external walls and parapets which can be
exposed to fire from a compartment situated below or adjacent to the respective external wall
3.1.3.6
fire activation risk
parameter taking into account the probability of ignition, function of the compartment area and the
occupancy
3.1.3.7
fire load density
fire load per unit area related to the floor area q , or related to the surface area of the total enclosure,
f
including openings, q
t
3.1.3.8
fire load
quantity of energy which is released by complete combustion of all combustible materials in a
compartment or a localised fire area
Note 1 to entry: It is composed of the building contents (i.e. the compartment fire load) and of combustible
structural elements (i.e. the structural fire load).
3.1.3.9
fire scenario
qualitative description of the course of a fire with time identifying key events that characterize the fire
and differentiate it from other possible fires
Note 1 to entry: It typically defines the ignition and fire growth process, the fully developed stage and decay
stage together as well as systems that impact the course of the fire and the nature of local environment.
3.1.3.10
flash-over
simultaneous ignition of all the fire loads in a compartment
3.1.3.11
hydrocarbon fire curve
nominal fire curve for representing effects of a hydrocarbon type fire
3.1.3.12
localised fire
fire involving only a limited area of the compartment
3.1.3.13
opening factor
factor representing the amount of ventilation depending on the area of openings in the compartment
walls, on the height of these openings and on the total area of the enclosure surfaces
3.1.3.14
rate of heat release
heat (energy) released by a combustible product as a function of time
SIST EN 1991-1-2:2024
3.1.3.15
standard fire curve
nominal curve defined in EN 13501-2 for representing a model of a fully developed fire in a compartment
3.1.3.16
fire curve
gas temperature in the environment of member surfaces as a function of time
Note 1 to entry: These can be:
— nominal: conventional curves, adopted for classification or verification of fire resistance, e.g. the
standard fire curve, external fire curve, hydrocarbon fire curve;
— physically based: determined on the basis of fire models and the specific physical parameters defining
the conditions in the fire compartment.
3.1.4 Terms relating to heat transfer analysis
3.1.4.1
configuration factor
for radiative heat transfer from surface A to surface B, fraction of diffusely radiated energy leaving
surface A that is incident on surface B
3.1.4.2
convective heat transfer coefficient
convective heat flux to the member related to the difference between the bulk temperature of gas
bordering the relevant surface of the member and the temperature of that surface
3.1.4.3
emissivity
equal to absorptivity of a surface, i.e. the ratio between the radiative heat absorbed by a given surface
and that of a black body surface
3.1.4.4
net heat flux
energy, per unit time and surface area, definitely absorbed by members
SIST EN 1991-1-2:2024
3.2 Symbols and abbreviations
For the purposes of this document, the following symbols apply.
3.2.1 Latin upper case letters
A area of the fire compartment
A design value of indirect action due to fire
ind,d
A floor area of the fire compartment
f
A fire area
fi
A area of horizontal openings in roof of compartment
h
A
h,v
total area of openings in enclosure A A+A
( )
h,v h v
A area of enclosure surface j, openings not included
j
A total area of enclosure (walls, ceiling and floor, including openings)
t
A charring area of timber members
st
A
v
total area of vertical openings on all walls (AA= )
v ∑ v,i
i
A area of vertical opening i
v,i
C protection coefficient of member face i
i
D depth of the fire compartment, diameter of the fire
E design value of the relevant effects of actions from the fundamental combination according
d
to EN 1990
E constant design value of the relevant effects of actions in the fire situation
d,fi
E design value of the relevant effects of actions in the fire situation at time t
d,fi,t
E internal energy of gas
g
H distance between the fire source and the ceiling
H net calorific value including moisture
u
H net calorific value of dry material
u0
H net calorific value of material i
ui
L length of the core
c
L flame length along axis
f
L horizontal projection of the flame (from the facade)
H
L horizontal flame length
h
L flame height (from the upper part of the window)
L
L axis length from window to the point where the calculation is made
x
M amount of combustible material i
k,i
O
opening factor of the fire compartment
O= Ah / A
( )
v eq t
O reduced opening factor in case of fuel controlled fire
lim
=
SIST EN 1991-1-2:2024
P the internal pressure
int
Q rate of heat release of the fire
Q convective part of the rate of heat release Q
c
Q characteristic fire load
k,fi
Q characteristic fire load of material i
k,fi,i
*
heat release coefficient related to the diameter D of the local fire
Q
D
*
heat release coefficient related to the height H of the compartment
Q
H
Q characteristic value of the leading variable action
k,1
Q maximum rate of heat release
max
Q rate of heat release entering through openings by gas flow
in
Q rate of heat release lost through openings by gas flow
out
Q rate of heat release lost by radiation through openings
rad
Q rate of heat release lost by radiation and convection to the surfaces of the compartment
wall
R design value of the resistance of the member at normal temperature
d
R design value of the resistance of the member in the fire situation at time t
d,fi,t
RHR maximum rate of heat release per square meter
f
RHR rate of heat release per square meter of charring area of timber members
st
T temperature [K]
T ambient temperature [K]
amb
T initial temperature [K]
T temperature of the fire compartment
...
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