EN 1994-1-2:2005

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Eurocode 4 - Design of composite steel and concrete structures - Part 1-2: General rules - Structural fire designEvrokod 4: Projektiranje sovprežnih konstrukcij iz jekla in betona – 1-2. del: Splošna pravila – Požarnoodporno projektiranjeEurocode 4 - Calcul des structures mixtes acier-béton - Partie 1-2: Regles générales - Calcul du comportement au feuEurocode 4: Bemessung und Konstruktion von Verbundtragwerken aus Stahl und Beton - Teil 1-2: Allgemeine Regeln Tragwerksbemessung für den BrandfallTa slovenski standard je istoveten z:EN 1994-1-2:2005SIST EN 1994-1-2:2006en91.080.10Kovinske konstrukcijeMetal structures91.080.40Betonske konstrukcijeConcrete structures13.220.50Požarna odpornost gradbenih materialov in elementovFire-resistance of building materials and elements91.010.30Technical aspectsICS:SIST ENV 1994-1-2:2004/AC:2004SIST ENV 1994-1-2:20041DGRPHãþDSLOVENSKI
STANDARDSIST EN 1994-1-2:200601-februar-2006

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 1994-1-2August 2005ICS 13.220.50; 91.010.30; 91.080.10; 91.080.40Supersedes ENV 1994-1-2:1994
English VersionEurocode 4 - Design of composite steel and concrete structures- Part 1-2: General rules - Structural fire designEurocode 4 - Calcul des structures mixtes acier-béton -Partie 1-2: Règles générales - Calcul du comportement aufeuEurocode 4 - Bemessung und Konstruktion vonVerbundtragwerken aus Stahl und Beton - Teil 1-2:Allgemeine Regeln Tragwerksbemessung im BrandfallThis European Standard was approved by CEN on 4 November 2004.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards 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 translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.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 STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2005 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 1994-1-2:2005: E

2 Contents
Page
Foreword .5
Background of the Eurocode programme.5 Status and field of application of Eurocodes.6 National Standards implementing Eurocodes.6 Links between Eurocodes and harmonised technical specifications (ENs and ETAs) for products.7 Additional information specific for EN 1994-1-2.7 National annex for EN 1994-1-2.10
Section 1 General.11
1.1 Scope.11 1.2 Normative references.13 1.3
Assumptions.15 1.4
Distinction between Principles and Application Rules.15 1.5
Definitions.15 1.5.1
Special terms relating to design in general…………………….…………………….15 1.5.2
Terms relating to material and products properties.16 1.5.3
Terms relating to heat transfer analysis.16 1.5.4
Terms relating to mechanical behaviour analysis.16 1.6 Symbols.16
Section 2 Basis of design.26
2.1
Requirements.26 2.1.1
Basic requirements.26 2.1.2
Nominal fire exposure.26 2.1.3
Parametric fire exposure.27 2.2 Actions.27 2.3 Design values of material properties.27 2.4 Verification methods.28 2.4.1
General.28 2.4.2
Member analysis.29 2.4.3
Analysis of part of the structure.30 2.4.4
Global structural analysis.31
Section 3 Material properties.31
3.1
General.31 3.2
Mechanical properties.31 3.2.1
Strength and deformation properties of structural steel.31 3.2.2
Strength and deformation properties of concrete.33 3.2.3
Reinforcing steels.35 3.3 Thermal properties.36 3.3.1
Structural and reinforcing steels.36 3.3.2
Normal weight concrete.39 3.3.3
Light weight concrete.41 3.3.4
Fire protection materials.42 3.4 Density.42

3Section 4 Design procedures ………………………………………………………………….43
4.1 Introduction.43 4.2 Tabulated data.44 4.2.1
Scope of application.44 4.2.2
Composite beam comprising steel beam with partial concrete encasement.45 4.2.3
Composite columns.47 4.3 Simple Calculation Models.51 4.3.1
General rules for composite slabs and composite beams.51 4.3.2
Unprotected composite slabs.51 4.3.3
Protected composite slabs.52 4.3.4
Composite beams.53 4.3.5
Composite columns.61 4.4 Advanced calculation models.64 4.4.1
Basis of analysis.64 4.4.2
Thermal response.65 4.4.3
Mechanical response.65 4.4.4
Validation of advanced calculation models.65
Section 5 Constructional details.66
5.1 Introduction.66 5.2 Composite beams.66 5.3 Composite columns.67 5.3.1
Composite columns with partially encased steel sections.67 5.3.2
Composite columns with concrete filled hollow sections.67 5.4 Connections between composite beams and columns.68 5.4.1
General.68 5.4.2 Connections between composite beams and composite columns with steel sections encased in concrete.69 5.4.3 Connections between composite beams and composite columns with partially encased steel sections.70 5.4.4 Connections between composite beams and composite columns with concrete filled hollow sections.70 Annex A (INFORMATIVE)
Stress-strain relationships at elevated temperatures for
structural steels
Annex B (INFORMATIVE)
Stress-strain relationships at elevated temperatures for
concrete with siliceous aggregate
Annex C (INFORMATIVE) Concrete stress-strain relationships adapted to natural fires
with a decreasing heating branch for use in advanced
calculation models
Annex D (INFORMATIVE)
Model for the calculation of the fire resistance of unprotected composite slabs exposed to fire beneath the slab according to the standard temperature-time curve
D.1 Fire resistance according to thermal insulation 79 D.2 Calculation of the sagging moment resistance Mfi,Rd+ 80 D.3 Calculation of the hogging moment resistance Mfi,Rd- 82 D.4 Effective thickness of a composite slab 84 D.5 Field of application
4 Annex E (INFORMATIVE) Model for the calculation of the sagging and hogging moment resistances of a steel beam connected to a concrete slab and exposed to fire beneath the concrete slab.
E.1 Calculation of the sagging moment resistance Mfi,Rd+ 86 E.2 Calculation of the hogging moment resistance Mfi,Rd- at an intermediate support
(or at a restraining support) 87 E.3 Local resistance at supports 88 E.4 Vertical shear resistance 89
Annex F (INFORMATIVE)
Model for the calculation of the sagging and hogging moment resistances of a partially encased steel beam connected to a concrete slab and exposed to fire beneath the concrete slab according to the standard temperature-time curve. 90
F.1 Reduced cross-section for sagging moment resistance Mfi,Rd+ 90 F.2 Reduced cross-section for hogging moment resistance Mfi,Rd- 94 F.3 Field of application
Annex G (INFORMATIVE)
Balanced summation model for the calculation of the fire resistance of composite columns with partially encased
steel sections, for bending around the weak axis, exposed
to fire all around the column according to the standard temperature-time curve.
96 G.1 Introduction 96 G.2 Flanges of the steel profile 97 G.3
Web of the steel profile 97 G.4
Concrete 98 G.5 Reinforcing bars 99 G.6 Calculation of the axial buckling load at elevated temperatures 100 G.7 Eccentricity of loading 101 G.8 Field of application 101
Annex H (INFORMATIVE)
Simple calculation model for concrete filled hollow sections exposed to fire all around the column according to the standard temperature-time curve. 104
H.1 Introduction 104 H.2
Temperature distribution 104 H.3 Design axial buckling load at elevated temperature 104 H.4 Eccentricity of loading 105 H.5 Field of application
Annex I (INFORMATIVE)
Planning and evaluation of experimental models 109
I.1 Introduction 109 I.2 Test for global assessment 109 I.3
Test for partial information 109

5Foreword This European Standard EN 1994-1-2: 2005, Eurocode 4: Design of composite steel and concrete structures: Part 1-2 : General rules – Structural fire design, has been prepared by Technical Committee CEN/TC250 « Structural Eurocodes », the Secretariat of which is held by BSI.
CEN/TC250 is responsible for all Structural Eurocodes.
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 latest by March 2010.
This Eurocode supersedes ENV 1994-1-2: 1994.
According to the CEN-CENELEC Internal Regulations, the National Standard 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.
Background of the Eurocode programme In 1975, the Commission of the European Community decided on an action programme in the field of construction, based on article 95 of the Treaty. The objective of the programme was the elimination of technical obstacles to trade and the harmonisation of technical specifications. Within this action programme, the Commission took the initiative to establish a set of harmonised technical rules for the design of construction works which, in a first stage, would serve as an alternative to the national rules in force in the Member States and, ultimately, would replace them.
For fifteen years, the Commission, with the help of a Steering Committee with Representatives of Member States, conducted the development of the Eurocodes programme, which led to the first generation of European codes in the 1980’s.
In 1989, the Commission and the Member States of the EU and EFTA decided, on the basis of an agreement1 between the Commission and CEN, to transfer the preparation and the publication of the Eurocodes to the CEN through a series of Mandates, in order to provide them with a future status of European Standard (EN). This links de facto the Eurocodes with the provisions of all the Council’s Directives and/or Commission’s Decisions dealing with European standards (e.g. the Council Directive 89/106/EEC on construction products – CPD - and Council Directives 93/37/EEC, 92/50/EEC and 89/440/EEC on public works and services and equivalent EFTA Directives initiated in pursuit of setting up the internal market). The Structural Eurocode programme comprises the following standards generally consisting of a number of Parts: EN1990, Eurocode : Basis of structural design EN1991, Eurocode 1: Actions on structures EN1992, Eurocode 2: Design of concrete structures EN1993, Eurocode 3: Design of steel structures
1 Agreement between the Commission of the European Communities and the European Committee for Standardisation (CEN) concerning the work on EUROCODES for the design of building and civil engineering works (BC/CEN/03/89).

6 EN1994, Eurocode 4: Design of composite steel and concrete structures EN1995, Eurocode 5: Design of timber structures EN1996, Eurocode 6: Design of masonry structures EN1997, Eurocode 7: Geotechnical design EN1998, Eurocode 8: Design of structures for earthquake resistance EN1999, Eurocode 9: Design of aluminium structures Eurocode standards recognise the responsibility of regulatory authorities in each Member State and have safeguarded their right to determine values related to regulatory safety matters at national level where these continue to vary from State to State. Status and field of application of Eurocodes The Member States of the EU and EFTA recognise that EUROCODES serve as reference documents for the following purposes : – as a means to prove compliance of building and civil engineering works with the essential requirements of Council Directive 89/106/EEC, particularly Essential Requirement N°1 – Mechanical resistance and stability – and Essential Requirement N°2 – Safety in case of fire;
–
as a basis for specifying contracts for construction works and related engineering services ; – as a framework for drawing up harmonised technical specifications for construction products (ENs and ETAs). The Eurocodes, as far as they concern the construction works themselves, have a direct relationship with the Interpretative Documents2 referred to in Article 12 of the CPD, although they are of a different nature from harmonised product standards3. Therefore, technical aspects arising from the Eurocodes work need to be adequately considered by CEN Technical Committees and/or EOTA Working Groups working on product standards with a view to achieving full compatibility of these technical specifications with the Eurocodes. The Eurocode standards provide common structural design rules for everyday use for the design of whole structures and component products of both a traditional and an innovative nature. Unusual forms of construction or design conditions are not specifically covered and additional expert consideration will be required by the designer in such cases. National Standards implementing Eurocodes The National Standards implementing Eurocodes will comprise the full text of the Eurocode (including any annexes), as published by CEN, which may be preceded by a National title page and National foreword, and may be followed by a National annex.
2 According to Art. 3.3 of the CPD, the essential requirements (ERs) shall be given concrete form in interpretative documents for the creation of the necessary links between the essential requirements and the mandates for hENs and ETAGs/ETAs. 3 According to Art. 12 of the CPD the interpretative documents shall : a) give concrete form to the essential requirements by harmonising the terminology and the technical bases and indicating classes or levels for each requirement where necessary ; b) indicate methods of correlating these classes or levels of requirement with the technical specifications, e.g. methods of calculation and of proof, technical rules for project design, etc. ; c) serve as a reference for the establishment of harmonised standards and guidelines for European technical approvals. The Eurocodes, de facto, play a similar role in the field of the ER 1 and a part of ER 2.

7The National Annex may only contain information on those parameters which are left open in the Eurocode for national choice, known as Nationally Determined Parameters, to be used for the design of buildings and civil engineering works to be constructed in the country concerned, i.e. : –
values and/or classes where alternatives are given in the Eurocode; –
values to be used where a symbol only is given in the Eurocode; –
country specific data (geographical, climatic, etc), e.g. snow map; –
the procedure to be used where alternative procedures are given in the Eurocode; it may also contain: – decisions on the application of informative annexes, and –
references to non-contradictory complementary information to assist the user to apply the Eurocode. Links between Eurocodes and harmonised technical specifications (ENs and ETAs) for products. There is a need for consistency between the harmonised technical specifications for construction products and the technical rules for works4. Furthermore, all the information accompanying the
CE Marking of the construction products which refer to Eurocodes shall clearly mention which Nationally Determined Parameters have been taken into account. Additional information specific for EN 1994-1-2 EN 1994-1-2 describes the Principles, requirements and rules for the structural design of buildings exposed to fire, including the following aspects: Safety requirements EN 1994-1-2 is intended for clients (e.g. for the formulation of their specific requirements), designers, contractors and public authorities. The general objectives of fire protection 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 Directive 89/106/EEC gives the following essential requirement for the limitation of fire risks: "The construction works must be designed and built in such a way, that in the event of an outbreak of fire -
the load bearing resistance 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".
4 see Art.3.3 and Art.12 of the CPD, as well as clauses 4.2, 4.3.1, 4.3.2 and 5.2 of ID N°1. 5 see clauses 2.2, 3.2(4) and 4.2.3.3 of ID N°2

8 According to the Interpretative Document N°2 "Safety in Case of Fire5" the essential requirement may be observed by following various possibilities for fire safety strategies prevailing in the Member States like conventional fire scenarios (nominal fires) or “natural” (parametric) fire scenarios, including passive and/or active fire protection 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. Required functions and levels of performance can be specified either in terms of nominal (standard) fire resistance rating, generally given in national regulations or, where allowed by national fire regulations,
by referring to fire safety engineering for assessing passive and active measures. 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. are not given in this document, because they are subject to specification by the competent authority. Numerical values for partial factors and other reliability elements are given as recommended values that provide an acceptable level of reliability. They have been selected assuming that an appropriate level of workmanship and of quality management applies. 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 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 these 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. Application of this Part 1-2 is illustrated below. The prescriptive approach and the performance-based approach are identified. The prescriptive approach uses nominal fires to generate thermal actions. The performance-based approach, using fire safety engineering, refers to thermal actions based on physical and chemical parameters. For design according to this part, EN 1991-1-2 is required for the determination of thermal and mechanical actions to the structure.

9Prescriptive Rules(Thermal Actions given by Nominal Fire)TabulatedDataPerformance-Based Code(Physically based Thermal Actions)Selection of Simple orAdvanced Fire DevelopmentModelsAnalysis ofa MemberDetermination ofMechanical Actionsand BoundaryconditionsSelection ofMechanicalActionsAnalysis of Partof the StructureAnalysis ofEntire StructureSimple CalculationModelsSimple CalculationModels(if available)AdvancedCalculationModelsDesign ProceduresAdvancedCalculationModelsAdvancedCalculationModelsDetermination ofMechanical Actionsand BoundaryconditionsAnalysis ofa MemberAnalysis of Partof the StructureAnalysis ofEntire StructureDetermination ofMechanical Actionsand BoundaryconditionsDetermination ofMechanical Actionsand BoundaryconditionsSelection ofMechanicalActionsSimple CalculationModels(if available)AdvancedCalculationModelsAdvancedCalculationModelsAdvancedCalculationModels
Figure 0.1: Alternative design procedures
Design aids Apart from simple calculation models, EN 1994-1-2 gives design solutions in terms of tabulated data (based on tests or advanced calculation models) which may be used within the specified limits of validity. It is expected, that design aids based on the calculation models given in EN 1994-1-2, will be prepared by interested external organizations. The main text of EN 1994-1-2 together with informative Annexes A to I includes most of the principal concepts and rules necessary for structural fire design of composite steel and concrete structures.

10 National annex for EN 1994-1-2 This standard gives alternative procedures, values and recommendations for classes with notes
indicating where national choices may have to be made. Therefore the National Standard implementing EN 1994-1-2 should have a National annex containing all Nationally Determined Parameters to be used for the design of buildings to be constructed in the relevant country.
National choice is allowed in EN 1994-1-2 through clauses: – 1.1(16) – 2.1.3(2) – 2.3(1)P – 2.3(2)P – 2.4.2(3) – 3.3.2(9) – 4.1(1)P – 4.3.5.1(10)

11Section 1 General 1.1 Scope (1) This Part 1-2 of EN 1994 deals with the design of composite steel and concrete structures for the accidental situation of fire exposure and is intended to be used in conjunction with EN 1994-1-1 and EN 1991-1-2. This Part 1-2 only identifies differences from, or supplements to, normal temperature design. (2) This Part 1-2 of EN 1994 deals only with passive methods of fire protection. Active methods are not covered. (3) This Part 1-2 of EN 1994 applies to composite steel and concrete structures that are required to fulfil certain functions when exposed to fire, in terms of: - avoiding premature collapse of the structure (load bearing function); - limiting fire spread (flame, hot gases, excessive heat) beyond designated areas
(separating function). (4) This Part 1-2 of EN 1994 gives principles and application rules (see EN 1991-1-2) for designing structures for specified requirements in respect of the aforementioned functions and the levels of performance. (5) This Part 1-2 of EN 1994 applies to structures, or parts of structures, that are within the scope of EN 1994-1-1 and are designed accordingly. However, no rules are given for composite elements which include prestressed concrete parts. (6) For all composite cross-sections longitudinal shear connection between steel and concrete should be in accordance with EN 1994-1-1 or be verified by tests (see also 4.3.4.1.5 and Annex I). (7) Typical examples of concrete slabs with profiled steel sheets with or without reinforcing bars are given in Figure 1.1.
Trapezoidal profile
Re-entrant profile
Flat profile
Figure 1.1 Typical examples of concrete slabs with profiled steel sheets with or without reinforcing bars

12 (8) Typical examples of composite beams are given in Figures 1.2 to 1.5. The corresponding constructional detailing is covered in section 5. 123 Key 1 – Shear connectors 2 – Flat concrete slab or composite slab with profiled steel sheeting 3 – Profiles with or without protection Figure 1.2: Composite beam comprising steel beam with no concrete encasement 123 Key 1 – Optional 2 – Stirrups welded to web of profile 3 – Reinforcing bar
Figure 1.3: Steel beam with partial concrete encasement 1 Key 1 – Reinforcing bar 12 Key 1 – Reinforcing bar 2 – Shear connectors Figure 1.4: Steel beam partially encased in slabFigure 1.5: Composite beam comprising steel beam with partial concrete encasement
(9) Typical examples of composite columns are given in Figures 1.6 to 1.8. The corresponding constructional detailing is covered in section 5.

13 1 Key 1 – Shear connectors welded to
web of profile
Figure 1.6: Concrete encased profiles Figure 1.7: Partially encased profiles Figure 1.8: Concrete filled profiles
(10) Different shapes, like circular or octagonal cross-sections may also be used for columns. Where appropriate, reinforcing bars may be replaced by steel sections.
(11) The fire resistance of these types of constructions may be increased by applying fire protection materials. NOTE:
The design principles and rules given in 4.2, 4.3 and 5 refer to steel surfaces directly exposed to the fire, which are free of any fire protection material, unless explicitly specified otherwise. (12)P The methods given in this Part 1-2 of EN 1994 are applicable to structural steel grades S235, S275, S355, S420 and S460 of EN 10025, EN 10210-1 and EN 10219-1. (13) For profiled steel sheeting, reference is made to section 3.5 of EN 1994-1-1. (14) Reinforcing bars should be in accordance with EN 10080. (15) Normal weight concrete, as defined in EN 1994-1-1, is applicable to the fire design of composite structures. The use of lightweight concrete is permitted for composite slabs.
(16) This part of EN 1994 does not cover the design of composite structures with concrete strength classes lower than C20/25 and LC20/22 and higher than C50/60 and LC50/55. NOTE :
Information on Concrete Strength Classes higher than C50/60 is given in section 6 of EN 1992-1-2. The use of these concrete strength classes may be specified in the National Annex. (17) For materials not included herein, reference should be made to relevant CEN product standards or European Technical Approval (ETA). 1.2 Normative references (1)P This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). EN 1365 -1 Fire resistance tests for loadbearing elements – Part 1: Walls EN 1365 -2 Fire resistance tests for loadbearing elements – Part 2: Floors and roofs EN 1365 -3 Fire resistance tests for loadbearing elements – Part 3: Beams

14 EN 1365 -4 Fire resistance tests for loadbearing elements – Part 4: Columns EN 10025-1 Hot-rolled products of structural steels - Part 1: General technical delivery conditions EN 10025-2
Hot-rolled products of structural steels - Part 2: Technical delivery conditions for non-alloy structural steels EN 10025-3
Hot-rolled products of structural steels - Part 3: Technical delivery conditions for normalized/normalized rolled weldable fine grain structural steels EN 10025-4 Hot-rolled products of structural steels - Part 4:
Technical delivery conditions for thermomechanical rolled weldable fine grain structural steels EN 10025-5
Hot-rolled products of structural steels - Part 5:
Technical delivery conditions for structural steels with improved atmospheric corrosion resistance EN 10025-6
Hot-rolled products of structural steels - Part 6:
Technical delivery conditions for flat products of high yield strength structural steels in the quenched and tempered condition EN 10080 Steel for the reinforcement of concrete - Weldable reinforcing steel General EN 10210-1 Hot finished structural hollow sections of non-alloy and fine grain structural steels – Part 1 : Technical delivery conditions EN 10219-1 Cold formed welded structural hollow sections of non-alloy and fine grain structural steels – Part 1: Technical delivery conditions ENV 13381-1 Test methods for determining the contribution to the fire resistance of structural members – Part 1: Horizontal protective membranes ENV 13381-2 Test methods for determining the contribution to the fire resistance of structural members – Part 2: Vertical protective membranes
ENV 13381-3 Test methods for determining the contribution to the fire resistance of structural members – Part 3: Applied protection to concrete members
ENV 13381-4 Test methods for determining the contribution to the fire resistance of structural members – Part 4: Applied protection to steel members ENV 13381-5 Test methods for determining the contribution to the fire resistance of structural members – Part 5: Applied protection to concrete/profiled sheet composite members ENV 13381-6 Test methods for determining the contribution to the fire resistance of structural members – Part 6: Applied protection to concrete filled hollow sheet columns EN 1990
Eurocode: Basis of structural design EN 1991 -1-1 Eurocode 1 : Actions on Structures – Part 1.1: General Actions - Densities, self-weight and imposed loads EN 1991 -1-2 Eurocode 1 : Actions on Structures – Part 1.2: General Actions - Actions on structures exposed to fire

15EN 1991 -1-3 Eurocode 1 : Actions on Structures – Part 1.3: General Actions - Actions on structures - Snow loads EN 1991 -1-4 Eurocode 1 : Actions on Structures – Part 1.4: General Actions - Actions on structures - Wind loads EN 1992-1-1
Eurocode 2: Design of concrete structures - Part 1.1: General rules and rules for buildings EN 1992-1-2
Eurocode 2: Design of concrete structures - Part 1.2: Structural fire design EN 1993-1-1 Eurocode 3: Design of steel structures - Part 1.1: General rules and rules for buildings EN 1993-1-2 Eurocode 3: Design of steel structures - Part 1.2: Structural fire design
EN 1993-1-5 Eurocode 3: Design of steel structures - Part 1.5: Plated structural elements EN 1994-1-1 Eurocode 4: Design of composite steel and concrete structures - Part 1.1: General rules and rules for buildings" 1.3
Assumptions (1)P Assumptions of EN 1990 and EN 1991-1-2 apply. 1.4
Distinction between Principles and Application Rules (1) The rules given in EN 1990 clause 1.4 apply. 1.5
Definitions (1)P The rules given in clauses 1.5 of EN 1990 and EN 1991-1-2 apply (2)P The following terms are used in Part 1-2 of EN 1994 with the following meanings:
1.5.1 Special terms relating to design in general 1.5.1.1 axis distance distance between the axis of the reinforcing bar and the nearest edge of concrete 1.5.1.2 part of structure isolated part of an entire structure with appropriate support and boundary conditions 1.5.1.3 protected members members for which measures are taken to reduce the temperature rise in the member due to fire 1.5.1.4 braced frame a frame which
has a sway resistance supplied by a bracing system which is sufficiently stiff for it to be acceptably accurate to assume that all horizontal loads are resisted by the bracing system

16 1.5.2 Terms relating to material and products properties 1.5.2.1 failure time of protection duration of protection against direct fire exposure; that is the time when the fire protective claddings or other protection fall off the composite member, or other elements aligned with that composite member fail due to collapse, or the alignment with other elements is terminated due to excessive deformation of the composite member 1.5.2.2 fire protection material any material or combination of materials applied to a structural member for the purpose of increasing its fire resistance 1.5.3 Terms relating to heat transfer analysis 1.5.3.1 section factor for a steel member, the ratio between the exposed surface area and the volume of steel; for an enclosed member, the ratio between the internal surface area of the exposed encasement and the volume of steel 1.5.4 Terms relating to mechanical behaviour analysis 1.5.4.1 critical temperature of structural steel for a given load level, the temperature at which failure is expected to occur in a structural steel element for a uniform temperature distribution 1.5.4.2 critical temperature of reinforcement the temperature of the reinforcement at which failure in the element is expected to occur at a given load level 1.5.4.3 effective cross section cross section of the member in structural fire design used in the effective cross section method. It is obtained by removing parts of the cross section with assumed zero strength and stiffness 1.5.4.4 maximum stress level for a given temperature, the stress level at which the stress-strain relationship of steel is truncated to provide a yield plateau 1.6 Symbols
(1)P For the purpose of this Part 1-2 of EN 1994, the following symbols apply Latin upper case letters A cross-sectional area or concrete volume of the member per metre of member length Aa,θ cross-sectional area of the steel profile at the temperature θ Ac,θ cross-sectional area of the concrete at the temperature θ Af cross-sectional area of a steel flange

17Ai, Aj elemental area of the cross section with a temperature θi or θj
or the exposed surface area of the part i of the steel cross-section per unit length
A/Lr the rib geometry factor
Ai / Vi
section factor [m-1] of the part i of the steel cross-section (non-protected member) Am directly heated surface area of member per unit length Am /V section factor of structural member Ap,i
area of the inner surface of the fire protection material per unit length of the part i of the steel member
Ap,i / Vi
section factor [m-1] of the part i of the steel cross-section (with contour protection) Ar cross-sectional area of the stiffeners Ar /Vr section factor of stiffeners As,θ cross-sectional area of the reinforcing bars at the temperature θ E integrity criterion E 30 or E 60,.a member complying with the integrity criterion for 30, or 60. minutes in standard fire exposure
Ea characteristic value for the modulus of elasticity of structural steel at 20°C Ea,f characteristic value for the modulus of elasticity of a profile steel flange Ea,θ characteristic value for the slope of the linear elastic range of the stress-strain relationship of structural steel at elevated temperatures Ea,θ,σ tangent modulus of the stress-strain relationship of the steel profile at elevated temperature θ=and for stress σi,θ Ec,sec,θ characteristic value for the secant modulus of concrete in the fire situation, given by fc,θ divided by εcu,θ=Ec0,θ characteristic value for the tangent modulus at the origin of the stress-strain
relationship for concrete at elevated temperatures and for short term loading Ec,θ,σ tangent modulus of the stress-strain relationship of the concrete at elevated temperature θ=and for stress σi,θ Ed design effect of actions for normal temperature design Efi,d design effect of actions in the fire situation, supposed to be time independent Efi,d,t design effect of actions, including indirect fire actions and loads in the fire situation, at time t (EI)fi,c,z flexural stiffness in the fire situation (related to the central axis Z of the composite cross-section)

18 (EI)fi,eff effective flexural stiffness in the fire situation (EI)fi,f,z flexural stiffness of the two flanges of the steel profile in the fire situation (related to the central axis Z of the composite cross-section) (EI)fi,s,z flexural stiffness of the reinforcing bars in the fire situation (related to the central axis Z of the composite cross-section) (EI)fi,eff,z effective flexural stiffness (for bending around axis z) in the fire situation (EI)fi,w,z flexural stiffness of the web of the steel profile in the fire situation (related to the central axis Z of the composite cross-section) Ek characteristic value of the modulus of elasticity Es modulus of elasticity of the reinforcing bars Es,θ characteristic value for the slope of the linear elastic range of the stress-strain relationship of reinforcing steel at elevated temperatures Es,θ,σ tangent modulus of the stress-strain relationship of the reinforcing steel at elevated temperature θ=and for stress σi,θ Fa compressive force in the steel profile
F +, F - total compressive force in the composite section in case of sagging or hogging bending moments Fc compression force in the slab Gk characteristic value of a permanent action HC hydrocarbon fire exposure curve I thermal insulation criterion Ii,θ second moment of area, of the partially reduced part i of the cross-section for bending around the weak or strong axis in the fire situation I 30 or I 60,. a member complying with the thermal insulation criterion for 30, or 60. minutes in standard fire exposure
L system length of a column in the relevant storey Lei buckling length of a column in an internal storey Let buckling length of a column in the top storey M bending moment Mfi,Rd+; Mfi,Rd - design value of the sagging or hogging moment resistance in the fire situation
Mfi,t,Rd design moment resistance in the fire situation at time t N number of shear connectors in one critical length,

19 or axial load Nequ equivalent axial load
Nfi,cr elastic critical load (≡ Euler buckling load) in the fire situation Nfi,cr,z elastic critical load (≡ Euler buckling load) around the axis Z in the fire situation Nfi,pl,Rd design value of the plastic resistance to axial compression of the total cross-section in the fire situation Nf
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