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CEN/TC 250 N 1069
CEN/TC 250CEN/TC 250 - Structural EurocodesEmail of secretary: [email protected] Secretariat: BSI (United Kingdom)
N 1069 CEN-TC250-WG7 N0001 EG EN1990 - Recommendations for amendments to EN 1990 "4-column-version".
Document type: Other committee document
Date of document: 2014-03-03
Expected action: INFO
Background:
Committee URL: http://cen.iso.org/livelink/livelink/open/centc250
CEN/TC 250/WG 7 N 1
CEN/TC 250/WG 7CEN/TC 250/WG 7 - EN 1990 Basis of structural designEmail of secretary: [email protected] Secretariat: SN (Norway)
EG EN1990 - Recommendations for amendments to EN 1990 - 2013-11-05
Document type: Other committee document
Date of document: 2014-01-21
Expected action: INFO
Background:
Committee URL: http://cen.iso.org/livelink/livelink/open/centc250wg7
CEN/TC 250 N 1069
CEN/TC250 STRUCTURAL EUROCODE
EN1990 BASIS OF STRUCTURAL DESIGN
EXPERT GROUP FOR EVOLUTION OF EN 1990
RECOMMENDATIONS FOR AMENDMENDS TO EN 1990
(at February 2013)
NOTE
This document has been prepared by the EG EN1990 and has the status of a “Working Draft”, it is intended for use by WG7 and its PTs, to serve as a basis for the future discussion on the evolution of EN 1990. The document is in evolution and will be completed/updated by WG7.
As recalled in the introduction hereafter, the recommendations are based on the comments received by the EN1990 review, submitted by some NSBs and other requirements made by TC250 sub-committees and CEN execution standards committees, up to February 2013.
Notwithstanding the above considerations, WG7 (London, 05.11.2013) agreed to circulate this draft within CEN/TC250, for information purposes only.
EXPERT GROUP:
H Gulvanessian S Leivestad
P Formichi P Luechinger
A Bond J Markova
J Bregulla J Sorenson
P Croce P Spehl
S Denton T Vrouwenvelder
W Jaeger
Draft: 2013/11/05
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
2
Table of contents
Introduction ........................................................................................................................... 3
FOREWORD ........................................................................................................................ 5
Section 1 General ............................................................................................................... 15
Section 2 Requirements...................................................................................................... 19
Section 3 Principles of limit states design............................................................................ 26
Section 4 Basic Variables ................................................................................................... 29
Section 5 – Structural analysis and design assisted by testing............................................ 36
Section 6 Verification by the partial factor method.............................................................. 38
Annex A1 (normative) Application for Buildings................................................................... 47
Annex B .............................................................................................................................. 59
Annex C.............................................................................................................................. 80
Appendix 1 PROPOSAL FOR THE MINIMUM CONTENTS OF THE STRUCTURAL DESIGN REPORT ............................................................................................................ 108
Appendix 2 PROPOSAL FOR THE ULS VERIFICATIONS FORMAT STR/EQU/GEO...... 110
Appendix 3 BACKGROUND CALCULATIONS EQU/STR................................................. 117
Appendix 4 PROPOSAL FOR THE AMENDMENT OF TABLE A1.2(B) ............................ 119
Appendix 5 - ALTERNATIVE PROPOSAL BY WOLFRAM JÄGER FOR ANNEX B.......... 121
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
3
Introduction
The EG was set up by TC250 through its resolution n. 2431 at the meeting in Limassol (Cyprus) in October 2007, and met for the first time in Brussels on 2nd of July 2009.
Eight subsequent meetings were held until February 2013.
The EG worked on the comments given by the EN1990 review, submitted by some NSBs and other requirements made by TC250 sub-committees and CEN execution standards committees.
At these meetings it was decided that recommendations for changes from the EG should be presented in a consistent four column version style as follows:
Column 1: list all Clause numbers
Column 2: gives the current (EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010) content of a clause for which a change is recommended
Column 3: if no change is recommended to a Clause then in Column 3 “no change” is written; if a change is recommended to a Clause, Column 3 gives the proposed new Clause with highlighting so that suggested amendments are readily identified
Column 4: where changes are recommended, gives the background for the recommendation
This report gives the whole set of recommendations agreed by the EG until February 2013.
In preparing the recommendations the EG gave strong consideration to the needs of practitioners and the need for stability of EN1990.
Decisions were also taken to keep annexes B, C and D informative.
The main recommendations for changes include:
- Changes requested by NSBs;
1 Resolution 243 (CEN/TC 250, Limassol, 15/16th October 2007)
Subject: EN 1990 - Results of the 5 year inquiry
CEN TC 250 notes the results of the 5 year review of EN 1990 “Basis of structural design” agreeing to the
confirmation and notes that a corrigendum will be issued as soon as possible.
CEN/TC also agrees to the formation of an expert Group, under the Convenorship of Prof Haig Gulvanessian, to
prepare the first revision of EN 1990.
The resolution was agreed by unanimity.
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
4
- New guidance on non linear analysis (requested by CEN/TC250/SC2) and design for fatigue (requested by CEN/TC250/SC2-SC3). These are general clauses which will be duly implemented in the relevant material codes;
- Changes to Annex B (requested by CEN/TC250/SC3 and steel and aluminium execution standards), and improving the clarity of annex C.
In addition the recommendations include five Appendices for the future WG/PT to consider as follows:
• Proposal for the minimum contents of the Structural Design Report
• Proposals for the verification format for STR, EQU, GEO, more appropriate for structures below ground
• Background calculations for EQU/STR
• Proposal for the amendment of Table A1.2(B)
• Alternative proposals for Annex B made by Wolfram Jaeger.
Accompanying this document the EG has prepared a “track change” version of EN 1990 showing all the recommendations. Annex A2 (bridges) has not yet been developed. Initial drafts of Annex A3 (towers and masts) is included and advanced drafts of Annexes A4 (silos and tanks) and A5 (cranes and machinery) are included.
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
5
FOREWORD
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
Foreword
This document (EN 1990:2002) has been prepared
by Technical Committee CEN/TC250 "Structural
Eurocodes", the secretariat of which is held by BSI.
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
October 2002, and conflicting national standards
shall be withdrawn at the latest by March 2010.
This document supersedes ENV 1991-1:1994.
CEN/TC 250 is responsible for all Structural
Eurocodes.
According to the CEN/CENELEC Internal
Regulations, the national standards organizations
of the following countries are bound to
implement this European Standard: Austria,
Belgium, Czech Republic, Denmark, Finland,
France, Germany,
Greece, Iceland, Ireland, Italy, Luxembourg, Malta,
Netherlands, Norway, Portugal,Spain, Sweden,
Switzerland and the United Kingdom.
This European Standard (EN 1990:xxxx) has been
prepared by Technical Committee CEN/TC 250
"Structural Eurocodes", the secretariat of which is
held by BSI.
This European Standard shall be given the status
of a national standard. According to the
CEN/CENELEC Internal Regulations, the National
Standards Organizations of EU and EFTA Member
States are bound to implement this European
Standard.
This document supersedes EN 1990: 2002 +
A1:2005 and including corrigenda dated
December 2008 and April 2010.
CEN/TC 250 is responsible for all Structural
Eurocodes.
This paragraph has been
updated and the list of, the
national standards
organizations of the countries
is removed in accordance with
current CEN procedures.
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
6
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
Foreword to amendment A1
This European Standard (EN 1990:2002/A1:2005)
has been prepared by Technical Committee
CEN/TC 250 “Structural Eurocodes”, the
secretariat of which is held by BSI. This
Amendment to the EN 1990:2002 shall be given
the status of a national standard, either by
publication of an identical text or by
endorsement, at the latest by June 2006, and
conflicting national standards shall be withdrawn
at the latest by June 2006. 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.
No need for this part of the
foreword in the new version.
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
7
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
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 national provisions the 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
In 1975, the Commission of the European
Community decided on an action programme in
the field of construction, based on article 95 of
the 1957 Treaty of Rome. 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 intended to replace the national provisions
in the Member States.
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 standards in the 1980’s.
In 1989, the Commission and the Member States
of the EU and EFTA decided, on the basis of an
agreement2 between the Commission and CEN, to
transfer the preparation and the publication of
Increased clarity and corrected
terminology (e.g. European
Standards and not European
Codes) has been used.
Updated references for the
CPR and the Procurement
Directives are given.
Notice given that the list of
Eurocodes will increase as new
Eurocodes are developed.
2 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).
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
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the Eurocodes to 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 standa rds (e.g.
the Council Directive 89/106/EEC on construction
products - CPD – and on Council Directives
2004/17/EC and 2004/18/EC 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:
EN 1990 Eurocode : Basis of Structural 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 structures
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
the Eurocodes to CEN through a series of
Mandates, in order to provide them with a status
of European Standard (EN) at the end of the
development process. 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 -
Construction Product Directive CPD – replaced by
the Regulation (EU) N° 305/2011 – Construction
Product Regulation (CPR) and Council Directive
2004/17/EC and 2004/18/EC 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:
EN 1990 Eurocode : Basis of structural 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 structures
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
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
9
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.
[N.B. New Eurocodes or Eurocode Parts will be
added later]
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
The Member States of the EU and EFTA recognise
that Eurocodes serve as reference documents for
the following purposes:
– to prove compliance of building and civil
engineering works or parts thereof with the Basic
Requirement for Construction Works N°1
Mechanical resistance and stability, a part of the
Basic Requirement for Construction Works N°2
Safety in case of fire and a part of Basic
Requirement for Construction Works N°7
Sustainable use of natural resources; as defined in
Annex I of the Regulation No.305/2011
– as a basis for specifying contracts for
construction works and related engineering
Services expressing in technical terms, the Basic
Requirement for Construction Works applicable to
the works and parts thereof;
– as normative reference standards for drawing
up harmonised technical specifications for
This clause has been altered so
that it is in accordance with
the CPR.
References to essential
requirements are replaced by
Basic Requirement for
Construction Works
In accordance with the CPR
reference is made to CEN
Technical Committees and/or
TAB (Technical Assessment
Bodies) Working Groups
working on harmonised
technical specifications.
Based on a decision made at
the CEN/TC250 meeting in
Berlin on 2 to 3 May 2012 the
reference to Essential
Requirement No 4 – Safety in
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
10
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 and ETAGS with a view to achieving a
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 parts of works and
structural construction products of both a
traditional and an in-novative 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.
structural construction products (ENs and ETAs)
and determining the performance of structural
components and kits with regard to mechanical
resistance and stability and resistance to fire,
insofar as it is part of the information of the
declaration of performance and CE-marking (e.g.
declared values or classes).
Technical aspects arising during the development
of the Eurocodes need to be adequately
considered by CEN Technical Committees and/or
TAB (Technical Assessment Bodies) Working
Groups working on harmonised technical
specifications in order to achieve 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 parts of works and
structural construction products of both a
traditional and an innovative nature. Some types
of Construction Works (e.g. nuclear structures,
large dams) or design conditions that are not
specifically covered will require additional
provisions and additional expert consideration by
the designer.
Use has been removed. (N.B.
This had already been
removed in the last revision)
To provide increased clarity
“Unusual forms of construction
or design conditions are not
specifically covered and
additional expert consideration
will be required by the
designer in such cases.” has
been replaced by “Some types
of Construction Works (e.g.
nuclear structures, large dams)
or design conditions that are
not specifically covered will
require additional provisions
and additional expert
consideration by the designer.”
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
11
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
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.
The 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,
– references to non-contradictory complementary
information to assist the user to apply the
Eurocode.
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.
The 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,
– references to non-contradictory complementary
information to assist the user to apply the
Eurocode.
Minor editorial changes only
here.
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
12
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
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 provisions
for works. Furthermore, all the information
accompanying the CE Marking of the construction
products which use the Euro- codes shall clearly
mention which Nationally Determined Parameters
have been taken into account.
There is a need for consistency between the
harmonised technical specifications for structural
construction products and the technical provisions
for works. Furthermore, all the information in the
declaration of performance of the construction
products which refer to the Eurocodes shall
clearly mention which Nationally Determined
Parameters have been taken into account.
Wording changed as
appropriate to be in
accordance with the CPR
Additional information specific to EN 1990
EN 1990 describes the Principles and
requirements for safety, serviceability and
durability of structures. It is based on the limit
state concept used in conjunction with a partial
factor method.
For the design of new structures, EN 1990 is
intended to be used, for direct application,
together with Eurocodes EN 1991 to 1999.
EN 1990 also gives guidelines for the aspects of
structural reliability relating to safety,
serviceability and durability :
– for design cases not covered by EN 1991 to EN
1999 (other actions, structures not treated, other
materials) ;
– to serve as a reference document for other CEN
TCs concerning structural matters.
EN 1990 is intended for use by :
– committees drafting standards for structural
EN 1990 describes the Principles and
requirements for safety, robustness, serviceability
and durability of structures. It is based on the limit
state concept used in conjunction with a partial
factor method.
For the design of new structures, EN 1990 is
intended to be used, for direct application,
together with the whole set of the Eurocodes.
EN 1990 also gives guidelines for the aspects of
structural reliability relating to safety,
serviceability and durability:
– for design cases not covered by the whole set of
the Eurocodes (other actions, structures not
treated, other materials);
– to serve as a reference document for other CEN
TCs concerning structural matters.
EN 1990 is intended for use by:
– committees drafting standards for structural
Robustness has been added in
the 1st
paragraph.
“Eurocodes EN 1991 to 1999”
has been replaced as
appropriate by “the whole set
of the Eurocodes” in
anticipation of new Eurocodes
on glass etc..
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
13
design and related product, testing and execution
standards ;
– clients (e.g. for the formulation of their specific
requirements on reliability levels and durability) ;
– designers and constructors ;
– relevant authorities.
EN 1990 may be used, when relevant, as a
guidance document for the design of structures
outside the scope of the Eurocodes EN 1991 to EN
1999, for :
- assessing other actions and their combinations ;
- modelling material and structural behaviour ;
- assessing numerical values of the reliability
format.
Numerical values for partial factors and other
reliability parameters are recommended as basic
values that provide an acceptable level of
reliability. They have been selected assuming that
an appropriate level of workmanship and of
quality management applies. When EN 1990 is
used as a base document by other CEN/TCs the
same values need to be taken.
design and related product, testing and execution
standards;
– clients (e.g. for the formulation of their specific
requirements on reliability levels and durability);
– designers and constructors;
– relevant authorities.
EN 1990 may be used, when relevant, as a
guidance document for the design of structures
outside the scope of the Eurocodes EN 1991 to EN
1999, for:
− assessing other actions and their combinations;
− modelling material and structural behaviour;
− assessing numerical values of the reliability
format.
Numerical values for partial factors and other
reliability parameters are recommended as basic
values that provide an acceptable level of
reliability. They have been selected assuming that
an appropriate level of workmanship and of
quality management applies. When EN 1990 is
used as a base document by other CEN/TCs the
same values need to be taken.
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
14
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
National annex for EN 1990
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 1990 should have a National
annex containing all
Nationally Determined Parameters to be used for
the design of buildings and civil engineering works
to be constructed in the relevant country.
National choice is allowed in EN 1990 A1 through
National choice is allowed in EN 1990 A2 through
This standard gives alternative procedures,
recommendations for values and classes with
notes indicating where national choices may have
to be made. Therefore the National Standard
implementing EN 1990 should have a National
Annex containing all Nationally Determined
Parameters to be used for the design of buildings
and civil engineering works to be constructed in
the relevant country.
National choice is allowed in EN 1990 A1 through
National choice is allowed in EN 1990 A2 through
National choice is allowed in EN 1990 A3 through
National choice is allowed in EN 1990 A4 through
National choice is allowed in EN 1990 A5 through
(This chapter should be revised when the content
of the revised EN 1990 is known)
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
15
Section 1 General
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April
2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to
Clause
Background for recommendation
1.1 Scope
1.1 (1) No change
1.1 (2) No change
1.1 (3) No change
1.1 (4) No change
1.2 Normative references
1.2 No change: Additionally if new Eurocode
standards (e.g. glass, frp etc are cited in
normative clauses in the new EN 1990 they
have to be added to the list EN 1990 to EN
1999
1.3 Assumptions
1.3 (1) No change
1.3 (2) No change
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April
2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to
Clause
Background for recommendation
New 1.3 (3)
(3) Further to the general assumptions in
(2) the structure is assessed and
selected with due regard to the
relevant requirements to sustainability
in e.g. recyclability, durability and use
of environmentally compatible
materials.
The background for adding the (3) is Basic Works
requirement No 7 which states
7. Sustainable use of natural resources
The construction works must be designed, built
and demolished in such a way that the use of
natural resources is sustainable and ensure the
following:
(a) recyclability of the construction works, their
materials and parts after demolition;
(b) durability of the construction works;
(c) use of environmentally compatible raw and
secondary materials in the construction works.
Sustainability is a major concern, involved in most
human activities. On the level of standardization
this matter is dealt with in CEN by CEN TC 350.
How to handle sustainability on a Global,
European and national level is still not settled. By
the time of the next revision of EN 1990, hopefully
basic principles and methodology are agreed in
such a manner that it is mature for
standardisation, and how to implement
references to it in EN 1990 has become clear. The
scope of EN 1990 is to define the basic principles
applicable for design for "safety", it is not the
scope of EN 1990 to define the basic principles for
"sustainability", but it is pertinent for EN 1990 to
refer and relate to such requirements.
CEN/TC 250 N 1069
EN 1990 Expert Group: Recommendations for the evolution of EN 1990
Draft 2013/11/05
17
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April
2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to
Clause
Background for recommendation
1.4 Distinction between Principles and Application Rules
1.4 (1) No change
1.4 (2) No change
1.4 (3) No change
1.4 (4) No change
1.4 (5) No change
1.4 (6) No change
1.5 Terms and definitions
1.5 No change except for Clause 1.5.3.14 see
below). Additionally if new Eurocode
standards (e.g. glass, frp etc are cited in
normative clauses in the new EN 1990 it may
be necessary to add some new term and
definitions.
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April
2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to
Clause
Background for recommendation
1.5.3.14 characteristic value of an action (Fk) principal representative value of an action
NOTE In so far as a characteristic value can
be fixed on statistical bases, it is chosen so
as to correspond to a prescribed probability
of not being exceeded on the unfavourable
side during a "reference period" taking into
account the design working life of the
structure and the duration of the design
situation.
characteristic value of an action (Fk) principal representative value of an action
NOTE In so far as a characteristic value can be
fixed on statistical bases, it is chosen so as to
correspond to a prescribed probability of not
being exceeded on the unfavourable side.
during a "reference period" taking into account
the design working life of the structure and the
duration of the design situation.
The deleted part was causing confusion to
practitioners.
1.6 Symbols
1.6 No change. Additionally if new Eurocode
standards (e.g. glass, frp etc are cited in
normative clauses in the new EN 1990 it may
be necessary to add some new symbols.
CEN/TC 250 N 1069
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Section 2 Requirements
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
2.1 Basic requirements
2.1 (1)P
No change
2.1 (2)P
2 (P) A structure shall be designed to have adequate
:
– structural resistance,
– serviceability, and
– durability.
(2)P A structure shall be designed to have adequate :
– structural resistance,
– robustness
– serviceability, and
– durability and to
– comply with the assumptions for sustainability. See
1.3(3)
Robustness has been added to
the list as its adequacy is
essential.
Although there is not yet
consolidated methods and fully
harmonized approaches for
dealing with sustainability during
design the principles and
importance should be stated.
(from SL) What we can require is
that the structure, system,
materials etc. is in accordance
with the sustainability
assessment forming the basis for
the selection of construction, and
obtaining the approvals or alike
that will form the future system.
2.1 (3)P
No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
2.1 (4)P
No change
2.1 (5)P
No change
2.1 (6) No change
2.1 (7) (7) The provisions of Section 2 should be
interpreted on the basis that due skill and care
appropriate to the circumstances is exercised in the
design, based on such knowledge and good practice
as is generally available at the time that the design
of the structure is carried out.
2.1(7)P The provisions of Section 2 presuppose that the
design is carried out with the necessary skill and care
appropriate to the circumstances of the design. The
criteria in Section 2 shall be interpreted in the light of
the knowledge and good practice that are available at
the time that the design of the structure is carried out.
N.B. Those involved in design and
the Insurance Industry, have
asked whether this clause 2.1(7)
could be reworded to make it a
Principle.
New 2.1 (8)P
(8)P The design shall be documented with calculations
and drawings that are clear, legible and easy to check.
The objective of the proposed
Clause 2.1 (8)P The design shall
be documented with calculations
and drawings that are clear,
legible and easy to check is to
ensure that the design
information is correctly conveyed
to the contractor, checking
authority, client etc.
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
2.2 Reliability Management
2.2 (1)P
No change
2.2 (2) (2) Different levels of reliability may be adopted
inter alia :
– for structural resistance;
– for serviceability.
(2) Different levels of reliability may be adopted inter
alia :
– for structural resistance;
– for serviceability.
NOTE 1 Guidance may be given in the National annex
with regard to quality management measures,
reliability differentiation and the use of the provisions
dealt with in Annex B.
NOTE 2 Reliability differentiation rules have been
specified for particular aspects in the design
Eurocodes.
The background to the proposed
changes to this Clause are for
A more formal link between 2.2
and Annex A
2.2 (3) No change
2.2 (4) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
2.2 (5) (5) The levels of reliability relating to structural
resistance and serviceability can be achieved by
suitable combinations of:
a) preventative and protective measures (e.g.
implementation of safety barriers, active and
passive protective measures against fire, protection
against risks of corrosion such as painting or
cathodic protection);
b) measures relating to design calculations:
– representative values of actions;
– the choice of partial factors;
c) measures relating to quality management;
d) measures aimed to reduce errors in design and
execution of the structure, and gross human errors;
e) other measures relating to the following other
design matters:
– the basic requirements;
– the degree of robustness (structural integrity);
– durability, including the choice of the design
working life;
– the extent and quality of preliminary
investigations of soils and possible
environmental influences;
– the accuracy of the mechanical models used;
– the detailing;
f) efficient execution, e.g. in accordance with
execution standards referred to in EN 1991 to
EN 1999.
g) adequate inspection and maintenance according
to procedures specified in the project
documentation.
(5) The levels of reliability relating to structural
resistance and serviceability can be achieved by
suitable combinations of:
a) preventative and protective measures (e.g.
implementation of safety barriers, active and passive
protective measures against fire, protection against
risks of corrosion such as painting or cathodic
protection);
b) measures relating to design calculations:
– representative values of actions;
– the choice of partial factors;
NOTE See also Annex B
c) measures relating to quality management;
NOTE See also Annex B
d) measures aimed to reduce errors in design and
execution of the structure, and gross human errors;
NOTE See also Annex B
e) other measures relating to the following other
design matters:
– the basic requirements;
– the degree of robustness (structural integrity);
– durability, including the choice of the design
working life;
– the extent and quality of preliminary investigations
of soils and possible environmental influences;
– the accuracy of the mechanical models used;
– the detailing;
f) efficient execution, e.g. in accordance with execution
standards referred to in EN 1991 to EN 1999.
g) adequate inspection and maintenance according to
procedures specified in the project documentation.
The background to the proposed
changes to b) c) and d) in this
Clause are for
A more formal link between 2.2
and Annex A
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Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
2.3 Design working life
2.3 (1) (1) The design working life should be specified.
NOTE Indicative categories are given in Table 2.1.
The values given in Table 2.1 may also be used for
determining time-dependent performance (e.g.
fatigue-related calculations). See also Annex A.
Table 2.1 - Indicative design working life
Design working
life category
Indicative design
working life (years)
Examples
1 10 Temporary structures (1)
2 10 to 25 Replaceable structural
parts, e.g. gantry
girders, bearings
3 15 to 30 Agricultural and similar
structures
4 50 Building structures and
other common
structures
5 100 Monumental building
structures, bridges, and
other civil engineering
structures
(1) Structures or parts of structures that can be
dismantled with a view to being re-used should not
be considered as temporary.
(1)P The design working life shall be specified, and be
the basis for appropriate items including the durability
design and the basis for sustainability evaluations (see
1.3(3) and life cycle considerations.
NOTE Indicative categories are given in Table 2.1. The
values given in Table 2.1 may also be used for
determining time-dependent performance (e.g.
fatigue-related calculations). See also Annex A.
Table 2.1 - Indicative design working life Design
working life
category
Indicative design
working life (years)
Examples
1 10 Temporary structures (1)
2 10 to 25 Replaceable structural
parts, e.g. gantry girders,
bearings
3 15 to 30 Agricultural and similar
structures
4 50 Building structures and
other common structures
5 100 Monumental building
structures, bridges, and
other civil engineering
structures
(1) Structures or parts of structures that can be
dismantled with a view to being re-used should not be
considered as temporary.
The background for additional
information for this Clause is to
present useful additional
information on the importance of
the design working life.
The proposal is for paragraph (1)
to become a principle, stating
that the design working life shall
be used for the durability design,
and the basis for sustainability
and Life Cycle considerations.
(N.B. Note that for construction
products "reference life" is a
parameter that is used, for
structures designed with
durability according to the
Eurocodes, the design working life
could have this function, or
actually even better as it
considers the structure in its
actual environment.)
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
2.4 Durability
2.4 (1) P
(1)P The structure shall be designed such that
deterioration over its design working life does not
impair the performance of the structure below that
intended, having due regard to its environment and
the anticipated level of maintenance.
(1)P The structure shall be designed such that
deterioration over its design working life does not
impair the performance of the structure below that
intended, having due regard to its environment and
the anticipated level of maintenance.
NOTE Durability is an essential parameter when
assessing sustainability, durability of structures are
however a designed property and not a tested
property like for many construction products.
The background for this minor
amendment is to clarify that
durability of structures are
however a designed property and
not a tested property.
This note is added to reflect that
durability is a vital part of
sustainability, in the BWR7 of the
CPR.
(Note however that in EN 1990
context durability is a
requirement in order to maintain
structural safety, as we have no
allowance for deterioration in our
design procedures.)
2.4 (2) No change
2.4 (3)P
No change
2.4 (4) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
2.5 Quality management
2.4 (1) (1) In order to provide a structure that corresponds
to the requirements and to the assumptions made
in the design, appropriate quality management
measures should be in place. These measures
comprise:
– definition of the reliability requirements,
– organisational measures and
– controls at the stages of design, execution, use
and maintenance.
NOTE EN ISO 9001:2000 is an acceptable basis for
quality management measures, where relevant.
(1) In order to provide a structure that corresponds to
the requirements and to the assumptions made in the
design, appropriate quality management measures
should be in place. These measures comprise:
– definition of the reliability requirements,
– organisational measures and
– controls at the stages of design, execution, use and
maintenance.
NOTE EN ISO 9001:2000 is an acceptable basis for
quality management measures, where relevant, it may
however have to be supplemented with requirements
relevant for the particular design or execution as
appropriate. See Annex B.
This recommendation recognises
that EN ISO 9001 may not give
adequate guidance in relation to
design and execution of
construction works and a
reference to Annex B of EN 1990
has been made.
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Section 3 Principles of limit states design
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
3.1 General
3.1(1)P No change
3.1(2) No change
3.1(3) No change
3.1(4) No change
3.1(5) Verification of limit states that are concerned with
time dependent effects (e.g. fatigue) should be
related to the design working life of the
construction.
NOTE Most time dependent effects are cumulative.
Verification of limit states that are concerned
with time dependent effects (e.g. fatigue) should
be related to the design working life of the
construction.
NOTE 1 Most time dependent effects are
cumulative.
NOTE 2 For fatigue verifications of replaceable
structural parts it is possible to consider a
reduced design working life, provided that the
replacement is explicitly taken into account in the
design.
To clarify the concept of
design working life and of
replaceable parts.
3.2 Design Situations
3.2(1)P No change
3.2(2)P No change
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Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
3.2(3)P No change
3.3 Ultimate Limit States
3.3(1)P No change
3.3(2) No change
3.3(3) No change
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
3.3(4)P No change
An Appendix includes the
proposal for a re-arrangement
of the ULS list, consistently
with changes proposed in
Section 6 and Annex A1.
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
3.4 Serviceability Limit States
3.4(1)P No change
3.4(2)P No change
3.4(3) No change
3.5 Limit State Design
3.5(1)P No change
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3.5(2)P No change
3.5(3)P No change
3.5(4) No change
3.5(5) No change
3.5(6)P No change
3.5(7) No change
3.5(8)P No change
3.5(9) No change
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Section 4 Basic Variables
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
4.1 Actions and environmental influences
4.1.1 Classification of actions
4.1.1(1)P No change
4.1.1(2) No change
4.1.1(3) No change
4.1.1(4)P No change
4.1.1(5) No change
4.1.2 Characteristic values of actions
4.1.2(1)P No change
4.1.2(2)P No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
4.1.2(3) The variability of G may be neglected if G does not
vary significantly during the design working life of
the structure and its coefficient of variation is
small. Gk should then be taken equal to the mean
value.
NOTE This coefficient of variation can be in the
range of 0,05 to 0,10 depending on the type of
structure.
The variability of G may be neglected if G does
not vary significantly during the design working
life of the structure and its coefficient of variation
is small. Gk should then be taken equal to the
mean value.
NOTE Generally the coefficient of variation may
be considered small if it is not greater then 0,10,
except for members or structures subject to
overturning or uplift (EQU and UPL, see section
6), when it may be considered small if it is not
greater than 0,05.
Provide guidance on the use of
Gk,inf and Gk,sup
4.1.2(4) No change
4.1.2(5) The self-weight of the structure may be
represented by a single characteristic value and be
calculated on the basis of the nominal dimensions
and mean unit masses, see EN 1991-1-1.
NOTE For the settlement of foundations, see EN
1997.
Where the self-weight of the structure may be
represented by a single characteristic value, this
may be calculated on the basis of the nominal
dimensions and mean unit masses, see EN 1991-
1-1.
NOTE For the settlement of foundations, see EN
1997.
Align the rules with the
previous treatment of
variability of G.
4.1.2(6) No change
4.1.2(7)P No change
4.1.2(8) No change
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Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
4.1.2(9) No change
4.1.2(10) No change
4.1.2(11) Material properties to be used in first and second
order non-linear analyses may either be based on
design values, characteristic values, or mean
values provided a consistent safety concept is
used, that provide the same reliability as
intended by the use of conventional design
methods. Details for how non-linear analyses
may be performed for the various construction
materials are given in EN 1992 to EN 1999.
New clause, to implement
rules specific to non linear
analysis.
4.1.3 Other representative values of variable actions
4.1.3(1)P No change
4.1.4 Representation of fatigue actions
4.1.4(1) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
4.1.4(2) For structures outside the field of application of
models established in the relevant Parts of EN
1991, fatigue actions should be defined from the
evaluation of measurements or equivalent studies
of the expected action spectra.
NOTE For the consideration of material specific
effects (for example, the consideration of mean
stress influence or non-linear effects), see EN 1992
to EN 1999.
For structures outside the field of application of
models established in the relevant Parts of EN
1991, fatigue actions should be defined from the
evaluation of measurements or equivalent
studies of the expected action spectra.
NOTE 1 For the consideration of material specific
effects (for example, the consideration of mean
stress influence or non-linear effects), see EN
1992 to EN1995, EN 1998 and EN 1999.
NOTE 2 For bridges simplified fatigue verifications
may be performed using the Damage equivalent
coefficient method (λ-method) according to EN
1992 to EN 1995, EN 1998 and EN 1999, where
relevant, following the scheme given in the
informative Annex ….)
To provide a common basis to
λ-method as well as to λ-
coefficient given in different
ENs, especially in terms of
calibration of λ-values.
At present different
backgrounds are provided in
different ENs.
Note: In case the proposal is
agreed, a short Annex should
be prepared where precise
guidance is provided to
calibrate different λ-values,
providing appropriate
definitions for each of them.
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
4.1.4(3) (3) The fatigue load models in EN 1991 include
effects of accelerations caused by the actions,
either implicitly in the equivalent and frequent
fatigue load values, or explicitly by applying
dynamic enhancement factors to fatigue loads.
New Clause, to clarify the
significance of the load values
in fatigue load models
4.1.5 Representation of dynamic actions
4.1.5(1) The load models defined by characteristic values,
and fatigue load models, in EN 1991 may include
the effects of accelerations caused by the actions
either implicitly or explicitly by applying dynamic
enhancement factors.
NOTE Limits of use of these models are described
in the various Parts of EN 1991.
(1) The load models defined by characteristic
values, and fatigue load models, in EN 1991 may
include the effects of accelerations caused by the
actions either implicitly in the given load values
or explicitly by applying dynamic enhancement
factor to static and fatigue loads.
NOTE Limits of use of these models are described
in the various Parts of EN 1991.
To make the clause more
precise
4.1.6 Geotechnical actions
4.1.6(1)P No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
4.1.7 Environmental influences
4.1.7(1)P No change
4.1.7(2) No change
4.2 Material and product properties
4.2(1) No change
4.2(2) No change
4.2(3) No change
4.2(4)P No change
4.2(5) No change
4.2(6) No change
4.2(7) No change
4.2(8) No change
4.2(9) No change
4.2(10)P No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
4.3 Geometrical data
4.3(1)P No change
4.3(2) No change
4.3(3) No change
4.3(4) No change
4.3(5)P No change
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Section 5 – Structural analysis and design assisted by testing
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation.
5.1 Structural analysis
5.1.1 Structural
modelling
(4) First and second order non-linear finite
element analyses may be used for a more
accurate calculation of load effects and better
simulation of structural behaviour. Such analyses
may also be used to simulate potential failure
modes and predict ultimate capacity, provided
the results can be verified with satisfactory
accuracy compared to conventional methods.
Finally such analyses may be used in simulation of
both the load effects and the ultimate capacity at
failure in one combined analysis. Details for the
various materials are given in EN 1992 to EN
1999.
New clause to provide more
information for non-linear
analyses, especially when
applying non–linear Finite
Element analyses.
5.1.2 Static
actions
(3)P Effects of displacements and deformations
shall be taken into account in the context of
ultimate limit state verifications if they result in a
significant increase of the effects of actions.
NOTE Particular methods for dealing with effects of
deformations are given in EN l99l to EN l999.
To be agreed to quote this
reference only once in EN
1990. In this case a note in the
foreword should clarify that
further specific provisions are
given in EN 1991 to EN 1999.
5.1.3 Dynamic
actions
(7) Where dynamic actions cause vibrations of a
magnitude or frequencies that could exceed
(7) Where dynamic actions cause vibrations of a
magnitude or frequencies that could exceed
Clarify that the SLS verification
addressed here is specific to
CEN/TC 250 N 1069
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation.
serviceability requirements, a serviceability limit
state verification should be carried out.
NOTE Guidance for assessing these limits is given in Annex A
and EN 1992 to EN 1999.
serviceability requirements, a specific
serviceability limit state verification should be
carried out.
NOTE Guidance for assessing these limits is given in Annex A
and EN 1992 to EN 1999.
vibrations.
To be agreed the elimination
of all such references (see
comment to 5.1.2)
5.1.4 Fire
design
(2) The required performance of the structure
exposed to fire should be verified by either global
analysis, analysis of sub-assemblies or member
analysis, as well as the use of tabular data or test
results.
(2) The required performance of the structure
exposed to fire should be verified by global
analysis, or analysis of sub-assemblies or member
analysis, or the use of tabular data given in the
fire parts of Eurocodes, or test results.
Editorial to be further checked
5.2 Design assisted by testing
5.2(1) No change
5.2(2) No change
5.2(3) No change
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Section 6 Verification by the partial factor method
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
6.1 General
6.1(1)P No change
6.1(2) No change
6.1(3) No change
6.1(4) No change
6.1(5)P No change
6.1(6) Where first or second order non-linear finite
element analyses are used in analyses to simulate
both load effects and ultimate resistance the
concept of a global factor covering both
uncertainties on the action side and the material
side may be used as an alternative to the use of
design values directly. The global factor shall take
due account of the behaviour of the various
materials involved in the failure modes
investigated, as well as differences in the material
factors. Details for the various construction
materials are given in EN 1992 to EN 1999.
NOTE: the rules according to 6.4.3(4) should be
taken into account.
New clause, to implement
rules specific to non linear
analysis.
CEN/TC 250 N 1069
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
6.1(7) Where non-linear finite element analyses are
used to predict the ultimate capacity of a
structure the reliability of all individual structural
members shall as a minimum meet the required
level. The ultimate capacity of the structure
failing as a system should show an adequate
additional degree of robustness, covered by a
robustness factor γRRd. This factor depends on the
system characteristics. Further information is
given in Annex A.
NOTE 1 The required reliability index and the
calibration of safety factors is primarily done
based on previous experience. This implies that
system reliability normally can be expected to be
higher than the reliability of each individual
member. This is also consistent with the
assumptions for robustness and the required
ability of structures to sustain localised damage
from accidental loads or unknown causes without
total collapse.
NOTE 2 The National Annex may allow for
yielding or buckling of individual members at a
lower load level then prescribed by the ULS
requirement, provided sufficient deformation
capacity can be proven. Yielding at the
characteristic combination should always be
avoided.
New clause, to implement
rules specific to non linear
analysis.
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
6.1(8) Where non-linear analyses are used to document
the load bearing capacity to be in accordance
with the Eurocode, the material models with the
limitations of the Eurocodes and the detailing
rules of the relevant Eurocodes shall be applied.
Particular rules may be given where the analyses
are performed to document the capacity of
existing structures. Details for the various
construction materials are given in EN 1992 to EN
1999.
NOTE Software codes that deviate from the
Eurocodes cannot be used to document adequate
capacity in accordance with the Eurocodes, even
if the results are in reasonable agreement.
New clause, to implement
rules specific to non linear
analysis.
6.2 Limitations
6.2(1) No change
6.3 Design values
6.3.1 Design values of actions
6.3.1(1) No change
6.3.1(2) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
6.3.2 Design values of the effects of actions
6.3.2(1) No change
6.3.2(2) No change
6.3.2(3)P No change
6.3.2(4) No change
6.3.2(5) No change
6.3.3 Design values of materials or product properties
6.3.3(1) No change
6.3.3(2) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
6.3.4 Design values of geometrical data
6.3.4(1) No change
6.3.4(2)P No change
6.3.4(3) No change
6.3.5 Design resistance
6.3.5(1) No change
6.3.5(2) No change
6.3.5(3) No change
6.3.5(4) No change
6.4 Ultimate limit states
6.4.1 General
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Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
6.4.1(1)P ……
d) FAT : Fatigue failure of the structure or
structural members.
NOTE For fatigue design, the combinations of
actions are given in EN 1992 to EN 1995, EN 1998
and EN 1999.
……
……
d) FAT : Fatigue failure of the structure or
structural members.
NOTE For fatigue design, the combinations of
actions, where relevant, are given in EN 1991 to
EN1999.
……
Editorial
6.4.1(2)P No change
6.4.2 Verification of static equilibrium and resistance
6.4.2(1)P No change
6.4.2(2) No change
6.4.2(3)P No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
6.4.3 Combination of actions (fatigue verifications excluded)
6.4.3.1 General
6.4.3.1(1)P No change
6.4.3.1(2) No change
6.4.3.1(3) No change
6.4.3.1(4)P No change
6.4.3.1(5) No change
6.4.3.1(6) No change
6.4.3.2 Combinations of actions for persistent or transient design situations (fundamental combinations)
6.4.3.2(1) No change
6.4.3.2(2) No change
6.4.3.2(3) No change
6.4.3.2(4) No change
6.4.3.3 Combinations of actions for accidental design situations
6.4.3.3(1) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
6.4.3.3(2) No change
6.4.3.3(3) No change
6.4.3.3(4) No change
6.4.3.4 Combinations of actions for seismic design situations
6.4.3.4(1) No change
6.4.3.4(2) No change
6.4.4 Partial factors for actions and combination of actions
6.4.4(1) No change
6.4.5 Partial factors for materials and products
6.4.5(1) No change
6.5 Serviceability limit states
6.5.1 Verifications
6.5.1(1)P No change
6.5.2 Criteria
6.5.2(1) No change
6.5.3 Combination of actions
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
6.5.3(1) No change
6.5.3(2) No change
6.5.3(3) No change
6.5.3(4)P No change
6.5.4 Partial factors for materials
6.5.4(1) No change
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Annex A1 (normative) Application for Buildings
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
A1.1 Field of application
A1.1(1) This annex A1 gives rules and methods for establishing
combinations of actions for buildings. It also gives the
recommended design values of permanent, variable
and accidental actions and ψ factors to be used in the
design of buildings.
NOTE Guidance may be given in the National annex
with regard to the use of Table 2.1 (design working
life).
This annex A1 gives rules and methods for establishing
combinations of actions for buildings. It also gives the
recommended partial factors to be applied to the
characteristic values of permanent, variable and accidental
actions giving their design values, and ψ factors to be used
in the design of buildings.
NOTE Guidance may be given in the National annex with
regard to the use of Table 2.1 (design working life).
The proposed
formulation
focuses on partial
factors (which are
given here) rather
than design
values of actions.
A1.2 Combination of actions
A1.2.1 General
A1.2.1(1) No change
A1.2.1(2) No change
A1.2.1(3) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
A1.2.1(4) No change
A1.2.2 Values of ψ factors
A1.2.2(1)
Table A1.1
To clarify roof
loads Ψ factors
other than when
snow is
dominating, move
construction
loads Ψ factors
from EN 1991-1-
6, specify Ψ
values for ice and
water actions
A1.3 Ultimate limit states
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
A1.3.1 Design values of actions in persistent and transient design situations
A1.3.1(1) The design values of actions for ultimate limit states in
the persistent and transient design situations
expressions 6.9a to 6.10b) should be in accordance
with Tables A1.2(A) to (C).
NOTE The values in Tables A1.2 ((A) to (C)) can be
altered e.g. for different reliability levels in the
National annex (see Section 2 and Annex B).
The design values of actions for ultimate limit states in the
persistent and transient design situations expressions 6.9a
to 6.10b) should be in accordance with Tables A1.2(A) to
(C).
NOTE The values in Tables A1.2 ((A) to (C)) correspond, in
general, to RC2 with a 50 year standard reliability index
β=3.8 (see Section 2 and Annex B). They can be altered, e.g.
for different reliability levels, in the National annex.
A1.3.1(2) No change
A1.3.1(3) No change
A1.3.1(4) No change
A1.3.1(5) No change
A1.3.1(6) No change
A1.3.1(7) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
Table A1.2(A)
The present
formulation of
EQU verifications,
in those cases
where a
structural
member is
needed to
guarantee
equilibrium, may
lead to
contradictory
results. The
modification to
the combined
verification
factors, in NOTE
2, is intended to
achieve
consistency.
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
A1.3.2 Design values of actions in the accidental and seismic design situations
A1.3.2(1) No change
A1.4 Serviceability limit states
A1.4.1 Partial factors for actions
A1.4.1(1) No change
A1.4.2 Serviceability criteria
A1.4.2(1) No change
A1.4.2(2) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
A1.4.2(3)P The serviceability criteria for deformations and
vibrations shall be defined :
– depending on the intended use ;
– in relation to the serviceability requirements in
accordance with 3.4 ;
– independently of the materials used for supporting
structural member.
The serviceability criteria for deformations and vibrations
shall be defined :
– depending on the intended use ;
– in relation to the serviceability requirements in
accordance with 3.4 ;
– independently of the materials used for supporting
structural member.
NOTE Unless otherwise specified, recommended limiting
design values of the serviceability criteria for deformations
and vibrations are given in Table A1.7 and Table A1.8.
Give guidance on
the limit design
values of
serviceability
criteria
A1.4.3 Deformations and horizontal displacements
A1.4.3(1) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
A1.4.3(2) Vertical deflections are represented schematically
in Figure. A1.1.
Figure A1.1 - Definitions of vertical deflections
Key :
wc Precamber in the unloaded structural
member
w1 Initial part of the deflection under
permanent loads of the relevant
combination of actions according to
expressions (6.14a) to (6.16b)
w2 Long-term part of the deflection under
permanent loads
w3 Additional part of the deflection due to
the variable actions of the relevant
combination of actions according to
expressions (6.14a) to (6.16b)
wtot Total deflection as sum of w1 , w2 , w3
wmax Remaining total deflection taking into
account the precamber
Vertical deflections are represented schematically in
Figure. A1.1.
Figure A1.1 - Definitions of vertical deflections
The limiting design values of calculated vertical deflections
depend on the serviceability requirements.
NOTE Recommended limiting design values of static calculated
vertical deflections wmax are given in Table A1.6.”
Table A1.6 : Recommended limiting values of static calculated deflection wmax as a function of L, the span or twice the length of a cantilever
Serviceabili
ty
requiremen
t
Functioning of
structure
Comfort
of users
Appearance
of structure
Combinatio
n of actions
to be
considered
Characteristic,
expressions
(6.14a/b)
Frequent,
expression
(6.15a/b)
Quasi-
permanent,
expression
(6.16a/b)
Structure in
general
L/400 L/300 L/250
Secondary
structural
elements
L/200
See also National
Annexes :
• Belgium : NA to
EN 1990
• Finland : NA to
EN 1993-1-1, EN
1994-1-1 & EN
1995-1-
CEN/TC 250 N 1069
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Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
A1.4.3(3) If the functioning or damage of the structure or to
finishes, or to non-structural members (e.g. partition
walls, claddings) is being considered, the verification
for deflection should take account of those effects of
permanent and variable actions that occur after the
execution of the member or finish concerned.
NOTE Guidance on which expression (6.14a) to
(6.16b) to use is given in 6.5.3 and EN 1992 to EN 1999.
If the functioning or damage of the structure or to finishes,
or to non-structural members (e.g. partition walls,
claddings) is being considered, the verification for deflection
should take account of those effects of permanent and
variable actions that occur after the execution of the
member or finish concerned.
NOTE 1 Guidance on which expression (6.14a) to (6.16b) to
use is given in 6.5.3 and EN 1992 to EN 1999.
NOTE 2 The recommended limiting design values of static
deflections apply only to structures or structural
components without brittle partitions walls. If partitions
walls prone to cracking are used, appropriate detailing
should be adopted or more severe limiting design values of
deflection defined.
Make
recommended
values of static
deflections
consistent with
requirements of
functioning of
brittle partition
walls.
A1.4.3(4) No change
A1.4.3(5) No change
A1.4.3(6) No change
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
A1.4.3(7) Horizontal displacements are represented
schematically in Figure A1.2.
Figure A1.2 - Definition of horizontal
displacements
Key :
u Overall horizontal displacement over the building
height H
ui Horizontal displacement over a storey height Hi.
Horizontal displacements are represented schematically in
Figure A1.2.
Figure A1.2 - Definition of horizontal displacements
Key :
u Overall horizontal displacement over the building height
H
ui Horizontal displacement over a storey height Hi.
Horizontal deflections should satisfy the requirements of
functioning.
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Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
A1.4.3(7)
(continue)
NOTE Limiting design values of horizontal deflections are
recommended in Table A1.7.”
Table A1.7 : Recommended limiting design values of horizontal deflections as a function of height H of building or storey height Hi
Serviceability requirement
Functioning of structure
Comfort of users
Appearance of structure
Combination of actions to be considered
Characteristic, expressions (6.14a/b)
Frequent, expression (6.15a/b)
Quasi-permanent, expression (6.16a/b)
Single-storey buildings
H/400
Multi-storey buildings: -in general
Hi/200
-with brittle partition walls
Hi/500
See also National
Annexes :
• Belgium : NA
to EN 1990
• Finland : NA
to EN 1993-1-
1, EN 1994-1-
1 & EN 1995-
1-1
A1.4.4 Vibrations
A1.4.4(1) No change
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A1.4.4(2) For the serviceability limit state of a structure or a
structural member not to be exceeded when subjected
to vibrations, the natural frequency of vibrations of the
structure or structural member should be kept above
appropriate values which depend upon the function of
the building and the source of the vibration, and
agreed with the client and/or the relevant authority.
For the serviceability limit state of a structure or a structural
member not to be exceeded when subjected to vibrations,
the natural frequency of vibrations of the structure or
structural member should be kept above appropriate values
which depend upon the function of the building and the
source of the vibration, and agreed with the client and/or
the relevant authority.
NOTE Appropriate values of natural frequencies of vibration are
recommended in Table A1.8.”
Table A1.8 : Appropriate values of natural frequencies
Structures Critical frequency
Gymnasia and sport halls 8,0 Hz
Dance rooms
Concert halls without
permanent seating
7,0 Hz
Concert halls with
permanent seating
3,4 Hz
Table from the DK National Annex
See also National
Annexes :
• Belgium : NA
to EN 1991-1-
4 §6.3.2
Values to be
further discussed
in detail.
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Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
A1.4.4(3) No change
A1.4.4(4) No change
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Annex B
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
B1 Scope
and field of
application
(1) This annex provides additional guidance to 2.2
(Reliability management) and to appropriate clauses in
EN 1991 to EN 1999.
NOTE Reliability differentiation rules have been specified
for particular aspects in the design Euro- codes, e.g. in EN
1992, EN 1993, EN 1996, EN 1997 and EN 1998.
(1) This annex provides additional guidance to 2.2
(Reliability management), 2.5 (Quality management)
and to appropriate clauses in EN 1991 to EN 1999. The
Annex is applicable to the design and execution of new
construction works. The provisions related to quality
management may also be applied in case of retrofitting
of existing structures.
NOTE 1 : Reliability differentiation rules and quality
management measures have been specified for
particular aspects in EN 1990 Annexes A(3) and A(4) and
where relevant in the design Eurocodes, e.g. in EN 1992
to EN 1999.
NOTE 2: This annex is provided as guidance to the
writers of the national annex to EN 1990 and national
annexes to EN 1991 to 1999. This annex is intended to
provide the basis for a consistent system across the
complete suite of Eurocodes.
(2) It is assumed that the Quality management
requirements for both design and execution are applied
equally to all structures or structural components that are
designed to comply with this standard, whether they are
produced on site or in a factory. It is however accepted
that where the production is performed under a certified
inspection scheme of the factory production control, the
factory production control procedures may include the
specified activities that should otherwise be covered by an
external party.
Reliability is often referred to as the
probability of failure due to the
statistical variation of the
parameters involved in design and
execution, assuming all to be in
accordance with the standards for
materials, design and execution.
This is however only one part of the
reliability that society expects from
the built environment. Society is
interested in the actual reliability of
the structures, with due regard to
errors and flaws in design, materials
and execution.
For the Eurocodes to give society an
adequate level of safety the
Eurocodes must in addition to the
probability inherent in the standards
ensure a system that will remove
flaws and human errors in design
and execution to such an extent that
the overall resulting reliability is
acceptable to society.
The requirements for Quality
management should be identical for
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(2) The approach given in this Annex recommends the
following procedures for the management of structural
reliability for construction works (with regard to ULSs,
ex- cluding fatigue) :
a) In relation to 2.2(5)b, classes are introduced and
are based on the assumed consequences of
failure and the exposure of the construction works
to hazard. A procedure for allowing moderate
differentiation in the partial factors for actions and
resistances corresponding to the classes is given in
B3.
NOTE Reliability classification can be represented by �
indexes (see Annex C) which takes account of accepted or
assumed statistical variability in action effects and resistances
and model uncertainties.
b) In relation to 2.2(5)c and 2.2(5)d, a procedure for
allowing differentiation between various types of
construction works in the requirements for quality levels
of the design and execution process are given in B4 and
B5.
NOTE Those quality management and control measures
in design, detailing and execution which are given in B4
and B5 aim to eliminate failures due to gross errors, and
ensure the resistances assumed in the design.
(3) The procedure has been formulated in such a way so
as to produce a framework to al- low different reliability
levels to be used, if desired.
(3) The approach given in this Annex recommends the
following procedures for the management of structural
reliability for construction works:
a) In relation to 2.2(5)b, classes are introduced and are
based on the assumed consequences of failure and the
exposure of the construction works to hazard. A procedure
for allowing moderate differentiation in the partial factors
for actions and resistances corresponding to the classes is
given in B2.
NOTE Reliability classification can be represented by
differentiation of target levels of β indexes (see Annex C) which
takes account of accepted or assumed statistical variability in
action effects and resistances and model uncertainties.
b) In relation to 2.2(5)c and 2.2(5)d, a procedure for
allowing differentiation between various types of
construction works in the requirements for quality levels
of the design and execution process including
control/verification are given in B3 and recommendations
for a complete system is given in B4.
NOTE Those quality management and control measures in
design, detailing and execution which are given in B3.1 and B3.2
aim to eliminate failures due to gross errors, and avoid errors in
design and execution and thereby ensure a structure with the
intended performance.
(4) The procedure in this Annex has been formulated in
such a way so as to produce a framework for EN 1990
and EN 1992 to EN 1999 and the relevant product and
execution standards to allow differentiation of reliability
all structures or structural elements
designed to comply with the
Eurocodes, see (2).
In table B1 it is assumed a one-to-
one relationship between quality
management class, design quality
level, design supervision level,
execution class and inspection level,
this may however be differentiated.
This system must be consistent with
ISO 9000 in accordance with CEN
Directives §6.8, but it must be
detailed in the Eurocodes and
underlying standards (for execution
and materials) to give coherent and
technically adequate requirements
in a way that is adequate for the
way design and execution is
conducted in the construction
industry.
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levels to be used, as well as Quality management classes,
where allowed nationally.
Table B1 – Recommended system of quality
management classes (QM)
NOTE The system of Quality management classes to be used
in a Country and the detailed requirements for the various classes
may be given in the National Annex. The recommended system is
as given in Table B1.
B2 Symbols In this annex the following symbols apply.
KFI Factor applicable to actions for reliability
differentiation
β Reliability index
Delete.
Symbols are not needed
B3
Reliability
differentiati
on
B2 Reliability management
B2.1 Consequences classes
Edit reliability related clauses in separate chapter B2.
B3.1
Consequenc
es classes
(1) For the purpose of reliability differentiation,
consequences classes (CC) may be established
by considering the consequences of failure or
malfunction of the structure as given in Table B1.
(1) For the purpose of reliability differentiation,
consequences classes (CC) may be established by
considering the consequences of failure or
malfunction of the structure as given in Table B2.
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Table B1 - Definition of consequences classes
Table B2 - Definition of consequences classes
Add structures that are vital to the
function of society such as hospitals
and fire stations to CC3.
The way single family houses will fail
represents a very little risk to lives,
and these buildings may therefore
be allowed in CC1.
(2) The criterion for classification of consequences is
the importance, in terms of consequences of failure,
of the structure or structural member concerned. See
B3.3
(3) Depending on the structural form and decisions
made during design, particular members of the
structure may be designated in the same, higher or
lower consequences class than for the entire
structure.
NOTE At the present time the requirements for
reliability are related to the structural members of the
construction works.
(2) The criterion for classification of consequences is the
importance, in terms of consequences of failure, of the
structure or structural member concerned. See B2.3
(3) Depending on the structural form and decisions made
during design, particular members of the structure may
be designated in the same, higher or lower
consequences class than for the entire structure.
NOTE The requirements for reliability are related to
the structural members of the construction works,
the system reliability should for reasons of
robustness be higher than for the individual
members.
It is difficult to see how a system will
be able to provide adequate
robustness if the target reliability for
system failure shall be equal to the
minimum reliability for all individual
members.
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B3.2
Differentiati
on by ββββ
values
(1) The reliability classes (RC) may be
defined by the β reliability index concept.
(2) Three reliability classes RC1, RC2 and RC3 may be
associated with the three consequences classes CC1,
CC2 and CC3.
(3) Table B2 gives recommended minimum values for
the reliability index associated with reliability classes
(see also annex C).
B2.2 Differentiation by ββββ values
(1)The reliability classes (RC) may be defined by the β
reliability index concept.
(2) Three reliability classes RC1, RC2 and RC3 may be
associated with the three consequences classes CC1,
CC2 and CC3.
(3) Table B3 gives recommended target values for the
reliability index β for new structures associated with
reliability classes (see also Annex C) using a 50-year
reference period.
It is required, as a target, that the
annual probability of failure within
each reliability class shall be the
same independent of the design
working life of the structure.
The characteristic load used should
therefore be the same independent
of the reference period used for the
β-value. (1, 50 or 100 year reference
period)
Table B2 - Recommended minimum values for reliability index ββββ (ultimate limit states)
Table B3- Recommended target values for reliability index ββββ for new structures (ultimate
limit states)
In the present table the value of β
for 1 year reference period is based
on an annual value of the variable
load not the annual probability of
failure using the 2-% (50 year return
period). The variable load used for
the two columns should be the
same
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NOTE A design using EN 1990 with the partial factors given in
annex A1 and EN 1991 to EN 1999 is considered generally to lead
to a structure with a β value greater than 3,8 for a 50 year
reference period. Reliability classes for members of the structure
above RC3 are not further considered in this Annex, since these
structures each require individual consideration.
Note 1: The corresponding failure probabilities for the
reference period of 50 years are equal to 50 times the annual
values, which makes the two requirements in principle
equivalent. The difference is that the 50 years requirement
allows temporary higher annual failure probabilities for some
periods, if compensated by lower ones for others.
NOTE 2 A design using EN 1990 with the partial factors given in
annex A and EN 1991 to EN 1999 is considered generally to lead
to a structure in RC2.
NOTE 3 Reliability classes for members of the structure above
RC3 are not further considered in this Annex, since these
construction works and their members each require individual
consideration.
B3.3
Differentiati
on by
measures
relating to
the partial
factors
(1) One way of achieving reliability differentiation is by distinguishing classes of γF factors to be used in fundamental combinations for persistent design situations. For example, for the same design supervision and execution inspection levels, a multiplication factor KFI, see Table B3, may be applied to the partial factors.
B2.3 Differentiation by measures relating to the
partial factors
(1) One way of achieving reliability differentiation is by distinguishing classes of γF factors to be used in fundamental combinations for persistent design situations. Provided that the quality management system is according to Table B9, a multiplication factor KFI, see Table B4, may be applied to the
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partial factors.
Table B3 - KFI factor for actions
NOTE In particular, for class RC3, other measures as described
in this Annex are normally preferred to using KFI factors. KFI
should be applied only to unfavourable actions.
Table B4 –Recommended KFI factor for actions
NOTE Other measures as described in this Annex in Clauses B3
and B4 are normally preferred to using KFI factors to achieve
increased reliability, as it means less use of construction
materials.
It has been discussed to delete this
table. Increased reliability can be
achieved by use of quality
management procedures, which
means it is achieved without use of
additional materials, this should be
the preferred option.
Reduced reliability when permitted
should however also be achieved by
reduced material consumption i.e.
kFI <1,0 rather than more lenient
quality management.
(2) Reliability differentiation may also be applied
through the partial factors on resistance γM. However,
this is not normally used. An exception is in relation to
fatigue verification (see EN 1993). See also B6.
(3) Accompanying measures, for example the level of
quality control for the design and execution of the
structure, may be associated to the classes of γF. In this
Annex, a three level system for control during design
and execution has been adopted. Design supervision
levels and inspection levels associated with the
(2) Reliability differentiation may also be applied
through the partial factors on the material
parameters or resistance as an alternative to
applying the factors on the actions.
(3) Accompanying measures, for example the level of
quality control for the design and execution of the
structure, may be associated to the classes of γF.
However, this is not normally used.
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reliability classes are suggested.
(4) There can be cases (e.g. lighting poles, masts, etc.)
where, for reasons of economy, the structure might be
in RC1, but be subjected to higher corresponding
design supervision and inspection levels.
(4) Deleted
B2.4 Partial factors for resistance properties
(1) A partial factor for a material or product property or a member resistance may be reduced where a higher level of quality management than that required according to Table B9 or more severe requirements are used e.g. for a particular parameter like geometrical deviations. However, this is not normally used.
NOTE 1 Rules for various materials may be given or referenced where relevant in EN 1992 to EN 1999.
NOTE 2 Such a reduction, which allows for example for model uncertainties and dimensional variation, is not a reliability differentiation measure: it is only a compensating measure in order to keep the reliability level dependent on the efficiency of the control measures.
Text is moved
B4 Design
super-vision
differentiati
on
B3 Quality Management
B3.1 Design; reliability and quality management
differentiation
For the Eurocodes to give society an
adequate level of safety the
Eurocodes must in addition to the
probability inherent in the standards
ensure a system that will remove
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(1) Design supervision differentiation consists of various
organisational quality control measures which can be used
together. For example, the definition of design supervision
level (B4(2)) may be used together with other measures
such as classification of designers and checking authorities
(B4(3)).
(2) Three possible design supervision levels (DSL) are shown
in Table B4. The design supervision levels may be linked to
the reliability class selected or chosen according to the
importance of the structure and in accordance with National
requirements or the design brief, and implemented through
appropriate quality management measures. See 2.5.
(1) The designer should establish, document and
maintain a design quality management system (DQMS)
to ensure that design conforms to the agreed
performance requirements. The DQMS system should
consist of written procedures and adequate design
resources (personnel and equipment) as being fitted to
perform structural design covered by this European
Standard.
(2) Differentiation in the quality management of design
consists of various organisational quality measures which
can be used together. For example, design quality levels in
Table B5 can be used to differentiate the design effort in
relation to the complexity of the project, while design
supervision levels in Table B6 can be used to differentiate
the quality control and verification in relation to the
required reliability class as well as the complexity.
(3) Design supervision differentiation may also include a
classification of designers and/or design inspectors
(checkers, controlling authorities, etc.), depending on
their competence and experience, their internal
organisation, for the relevant type of construction works
being designed.
NOTE The type of construction works, the materials used and
the structural forms can affect this classification.
(4) Three design quality levels are shown in Table B5.
flaws and human errors in design
and execution to such an extent that
the overall resulting reliability is
acceptable to society.
This can only be achieved by a
Quality Management system
consisting of two major elements;
- a pro-active part in Quality
Assurance directed towards
ensuring that design and execution
will be done correctly by proper
organization, plans, procedures and
qualifications etc.
- a reactive part in Quality Control
which ensures that the design and
execution actually is correct by
control procedures covering;
inspection, testing, verification
(confirming that what is done is
done correctly), validation
(confirming that what is done was
the right thing to do) and review.
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These levels may be used to differentiate the requirements
for design management, level of experience and
competence of personnel and of the type of design tools
available to the design team for the various categories of
projects. The indicators for the choice of design quality
level can be both the consequences in case of failure and
the complexity of the task or a combination of both,
selected or chosen according to the importance of the
structure and in accordance with National requirements or
the design brief.
NOTE Complexity as input for the selection of Quality
Management Class can be of both administrative and
technological character, it is normally not an absolute but can be
considered relative to what is the normal field of activity and
experience as well as the competence and resources available in
the respective companies. Further guidance with respect to
complexity as indicator for selection of quality management
classes can be found where relevant in EN 1992 to EN 1999.
Table B5- Design quality levels (DQL)
The design quality levels in table B5
are intended for the pro-active part
(Quality Assurance) directed
towards ensuring that design will be
done correctly by proper
organization, plans, procedures and
qualifications etc.
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(5) Three design supervision levels (DSL) are shown in Table
B6. The design supervision levels may be linked to the
reliability class selected or chosen according to the
importance and complexity of the structure and in
accordance with National requirements or the design brief,
and implemented through appropriate quality
management measures. See 2.5.
Table B4 - Design supervision levels (DSL)
Table B6- Design supervision levels (DSL)
The design supervision levels in
table B5 are intended for the
reactive part (Quality Control) which
ensures that the design actually is
correct by control procedures
covering; inspection, testing,
verification, validation and review
(3) Design supervision differentiation may also include a
classification of designers and/or design inspectors
(checkers, controlling authorities, etc.), depending on
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their competence and experience, their internal
organisation, for the relevant type of construction works
being designed.
NOTE The type of construction works, the materials used and
the structural forms can affect this classification.
(4) Alternatively, design supervision differentiation can
consist of a more refined detailed assessment of the nature
and magnitude of actions to be resisted by the structure, or
of a system of design load management to actively or
passively control (restrict) these actions.
B5 Inspection during execution
(1) Three inspection levels (IL) may be introduced as
shown in Table B5. The inspection levels may be linked
to the quality management classes selected and
implemented through appropriate quality
management measures. See 2.5. Further guidance is
available in relevant execution standards referenced by
EN 1992 to EN 1996 and EN 1999.
B3.2 Execution quality management
differentiation
(1) The party performing the execution either in factory
or on site should establish, document and maintain an
execution quality management (EQM) system to ensure
that execution conforms to the agreed performance
requirements in the execution specification. The EQM
system should consist of written procedures and
adequate resources (personnel and equipment) as being
fitted to perform the work.
(2) Differentiation in the quality management of execution
consists of various organisational quality measures which
can be used together. Three execution classes are shown in
Table B7. Three inspection levels are shown in Table B8.
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Further guidance is available in relevant execution
standards referenced by EN 1992 to EN 1999.
NOTE EN 13670 and EN 1090 apply Execution classes and
gives requirements relevant for the execution and inspection
related to these classes.
(3) For construction products that are manufactured off
site to a harmonised European specification, the
differentiation in terms of execution quality management
should take into account the conformity assessment
requirements given in the relevant European specification.
NOTE Conformity assessment requirements may require
certification of the manufacturer’s system for factory production
control (FPC) by a competent certification body. In terms of Table
B8 this is above IL2 but below IL3 as it is external inspection of the
manufacturer’s process but not external inspection of specific
products. However, according to B1(2) it can be acceptable that
the external inspection of the specific product is covered by
specific procedures within the manufacturer’s system for FPC if
permitted by the National Annex, and a full IL3 is not required.
Table B7– Execution classes (EXC) The execution classes in table B7 are
intended for the pro-active part
(Quality Assurance) directed
towards ensuring that execution will
be done correctly by proper
organization, plans, procedures and
qualifications etc.
It is possible that execution
standards may use the execution
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class as the prime mechanism to
regulate both the proactive part and
the reactive part (inspection levels),
this is the case in EN 13670.
Table B5 - Inspection levels (IL)
Table B8 - Inspection levels (IL)
The inspection levels in table B8 are
intended for the reactive part
(Quality Control) which ensures that
the execution actually is correct by
control procedures covering;
inspection, testing, verification,
validation and review.
NOTE Inspection levels define the subjects to be covered by
inspection of products and execution of works including the
scope of inspection. The rules will thus vary from one structural
material to another, and are to be given in the relevant
execution standards.
NOTE Inspection levels define the subjects to be covered by
inspection of products and execution of works including the
scope of inspection. The rules will thus vary from one structural
material to another, and are to be given in the relevant
execution standards.
B6 Partial
factors for
resistance
properties
(1) A partial factor for a material or product property or
a member resistance may be reduced if an inspection
class higher than that required according to Table B5
and/or more severe requirements are used.
NOTE For verifying efficiency by testing see section 5 and Annex
Original text moved to B2.4
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D.
NOTE Rules for various materials may be given or referenced in
EN 1992 to EN 1999.
NOTE Such a reduction, which allows for example for model
uncertainties and dimensional variation, is not a reliability
differentiation measure : it is only a compensating measure
in order to keep the reliability level dependent on the
efficiency of the control measures.
B4 Recommendations for a quality management system
(1) Depending on the classification in B2 and B3
requirements for quality management (QM) should
be established. Quality assurance measures should
be considered by selection of appropriate design
levels (Table B5) and execution classes (Table B7).
Quality control of design and execution should be
established based on design supervision levels
(Table B6) and inspection levels (Table B8).
NOTE 1 Annex B gives the basic elements for a quality
management system. In order to establish adequate
confidence that structures designed according to the
Eurocodes will actually meet the intended safety, structures
should be classified with respect to consequences in case of
failure (Table B2) and required reliability class (Table B3)
NOTE 2 A detailed system for quality management in design
and execution may be given in the National annex. The system
specified in Table B1, B9 and B10 is recommended.
(2) Based on the consequences of failure and the
In this section are indicated how the
“building blocks” defined in the
previous sections can be built into a
system.
It is foreseen that this is done by the
various member states in their
national annexes to EN 1990 as well
as the material related Eurocodes
and underlying standards for
execution and materials.
It will not be correct at this stage to
enforce the same system on all
member states, but to encourage all
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required reliability a minimum class of quality
management shall be selected.
(3) A Higher class of quality management than that
which follows from (2) may be required for
technological reasons, i.e. where the risk of errors
are high due to novel techniques, complex or
difficult conditions etc. or from the choice of the
client and selected or chosen according to the
importance of the structure and in accordance with
National requirements or the design brief and
execution specification.
member states to build their
national system on the same
common building blocks, and with
due regard to their traditions in this
area.
Table B9 – Minimum requirement for reliability
classes and quality management classes related to
consequence classes.
In this table it is assumed a one-to-one relationship between consequence class, reliability class and quality management class, this may however be differentiated.
(4) The Quality management classes may be
subdivided into Design Quality Levels and Execution
Classes, where these classes can express
requirements to the management and organisation
of the design work and the execution. Within these
classes will also be the requirements for Design
Supervision Levels and Inspection levels, which can
be either directly associated to the Design and
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Execution Class or differentiated.
(5) A complete presentation of a recommended
system is given in table B10.
Table B10 – Recommended system relating quality management classes to management requirements
for design and execution
This table shows the same
information as table 1, but it is
detailed how both design
supervision and execution
inspection consists of multiple
levels of control.
This is also demonstrated by the
control pyramid included for
information at the end.
It is used three categories of
control for design and execution;
Selfcheck
Systematic check, internally
External check
The exact content of these
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categories and the level of
independence and other formal
requirements are up to the
various member states when
detailing the system to be used
in their country as it is clearly
seen to be within the
competence of the member
states as it clearly relates to
safety.
(5) The quality management routines for checking
of design (DSL) should have emphasis on those
parts of the structure where a failure would have
the larger consequences with respect to structural
resistance, durability and function, and as a
minimum cover;
- calculations and drawings
- agreement between calculations, drawings and
the execution specification
- critical components (members, nodes, joints,
supports and cross-section)
- loads, models for calculation of loads and design
situations
- structural models and calculation of load effects
Up to here Annex B has been
dealing with system related
matters, it is however also
important that the Eurocodes
focus on the technical matters of
concern, and which may be
further treated in the various
material related Eurocodes to
the extent they relate to design
and execution standards to the
extent they relate to execution
and materials.
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- adequate knowledge of soil conditions and the
design parameters
- where appropriate, separate checks as alternative
to review of design calculations
Additional guidance may be given in the various
design Eurocodes.
(6) The design shall be checked to an extent which
ensures adequate confidence that the design is
correct and complete. Personnel performing
internal systematic control and external control of
design shall have the same level of competence as
would be required to perform the work.
(7) The quality management routines for checking
of execution (IL) should have emphasis on those
parts of the structure where a failure would have
the larger consequences with respect to structural
resistance, durability and function, and as a
minimum cover;
- that the execution specification is available during
manufacture and on site
- that the execution is according to the execution specification
- that personnel have the skills and training required for the work
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- that inspection is properly documented
- materials and construction products are as specified
Additional guidance may be given in the various execution standards e.g. EN 13670 and EN 1090.
The execution shall be checked to an extent which
ensures adequate confidence that the work is
correct and complete in accordance with the
execution specification.
(8) The execution shall be checked to an extent
which ensures adequate confidence that the work
is correct and complete and in accordance with the
execution specification. Personnel performing
systematic control should have adequate
competence to assess the execution technically
including craftsmanship, and where appropriate
have the same level of competence as would be
required to perform the work. Personnel
performing external control should have such
competence that is required to ensure that the
execution is in compliance with the execution
specification.
The member states may also have specific requirements to the competence of personnel performing control, in particular external control by the client his representatives or by third party.
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NOTE The system for quality control of design and
execution described in section B4 can be illustrated by the
control pyramid in the figure. [NOTE: the figure should be
further developed once Annex B is agreed]
Control pyramid
INDEPENDENTDSL3 / IL3
INTERNAL SYSTEMATICDSL2 / IL2
SELF CHECKINGDSL1 IL1
Quality in a project should come from below, as “good quality work” from the very start. Not as “corrections” from above.
Design- and Execution class 3 [CC3/RC3 + special technology] Clients Quality System
Design- and Execution class 2 [CC2/RC2] Constructors Quality System
Design- and Execution class 1 [CC1/RC1] Constructors Quality System
Interface between ”project” and building authorities•Documentation•Audit
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Annex C
Note: The original text of Annex C given in the 3rd column is in blue colour, original text of Section 6 is in green colour.
Clause EN 1990:2002 + A1:2004 incorporating corrigenda December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation.
C1 Scope and field of applications
(1) This annex provides information and theoretical background to the partial factor method described in Section 6 and annex A. This Annex also provides the background to annex D, and is relevant to the contents of annex B. (2) This annex also provides information on − the structural reliability methods; − the application of the reliability-based method to determine by calibration design values and/or partial factors in the design expressions − the design verification formats in the Eurocodes.
Further guidance may be found in ISO 2394, JCSS Probabilistic Model Code and JCSS Risk Assessment in Engineering - Principles, System Representation & Risk Criteria.
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Background for recommendation.
NOTE: The majority of structures can be designed according to
the suite of Eurocodes EN 1990 to EN1999 without any need for
the application of the material presented in this annex.
Application may however be considered useful for design
situations that are not well covered and for possible extensions
of the code.
C2 Symbols
Added new symbols:
Pft target failure probability
βt target reliability index
Deleted: Prob(.) Probability
C4 Overview of reliability methods
(3) In both the Level II and Level III methods the measure of reliability should be identified with the survival probability Ps = (1 - Pf), where Pf is the failure probability for the considered failure mode and within an appropriate reference period. If the calculated failure probability is larger than a pre-set target value P0 then the structure should be considered to be unsafe.
(3) In both the Level II and Level III methods the measure of reliability should be identified with the survival probability Ps = (1 - Pf), where Pf is the failure probability for the considered failure mode and within an appropriate reference period. If the calculated failure probability is larger than a pre-set target value Pft then the structure should be considered to be unsafe.
C.5 Reliability index ββββ
(1) In the Level II procedures, an alternative measure of reliability is conventionally defined by the reliability index β which is related to Pf by:
)Φ( β−=fP (C.1)
where Φ is the cumulative distribution function of the
C.5 Probability of failure and reliability index ββββ
C.5.1 Uncertainty modelling
(1) Fundamentally, the calculation of the probability of failure shall take basis in all available knowledge, and the uncertainty representation shall include all relevant causal and stochastic dependencies as well as temporal and
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Background for recommendation.
standardised Normal distribution. The relation between Pf and β is given in Table C1. Table C1 - Relation between ββββ and Pf
Pf 10-1 10-2 10-3 10-4 10-5 10-6 10-7
β 1,28 2,32 3,09 3,72 4,27 4,75 5,20
(2) The probability of failure Pf can be expressed through a performance function g such that a structure is considered to survive if g > 0 and to fail if g ≤ 0:
Pf = Prob(g ≤ 0) (C.2a)
If R is the resistance and E the effect of actions, the
performance function g is :
g = R – E (C.2b)
with R, E and g random variables.
spatial variability. The appropriate choice of method for the calculation of the failure probability depends on the characteristics of the problem at hand, and especially on whether the problem can be considered as being time-invariant and whether the problem concerns individual failure modes or systems. C.5.2 Time-invariant reliability problems
(1) In case the problem does not depend on time (or spatial characteristics), or may be transformed such that it does not, e.g. by use of extreme value considerations, three types of methods may in general be used to compute the failure probability Pf, namely:
a) FORM/SORM (First/Second Order Reliability Methods)
b) Simulation techniques, e.g. crude Monte Carlo simulation, importance sampling, asymptotic sampling, subset simulation and adaptive sampling
c) Numerical integration. (2) In the FORM the probability of failure Pf is related to the reliability index β by
)Φ(f β−=P (C.1)
where Φ is the cumulative distribution function of the standardised Normal distribution. The relation between Pf and β is given in Table C1. Table C1 - Relation between ββββ and Pf
Pf 10-1 10-2 10-3 10-4 10-5 10-6 10-7
β 1,28 2,32 3,09 3,72 4,27 4,75 5,20
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Background for recommendation.
(3) If g is Normally distributed, β is taken as :
g
g
σµ
β = (C.2c)
where :
µg is the mean value of g, and
σg is its standard deviation,
so that :
0=− ggµ βσ (C.2d)
(3) The probability of failure Pf can be expressed through a performance function g such that a structure is considered to survive if g > 0 and to fail if g ≤ 0:
Pf = P(g ≤ 0) (C.2a)
(4) If R is the resistance and E the effect of actions,
the limit state equation or performance function g
is:
g = R – E (C.2b)
with R and E statistically independent random
variables.
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Background for recommendation.
and
)(Prob)0(Prob ggf µggP βσ−≤=≤= (C.2e)
For other distributions of g, β is only a
conventional measure of the reliability
Ps = (1 - Pf).
NOTE: In case of dependency between the load effect and the resistance, as e.g. often may be the case in geotechnical design, the procedure should be applied to other independent basic variables. (5) If R and E are Normally distributed, β is obtained as:
22
ER
ER
σσµµβ
+
−= (C.2c)
where:
Rµ , Eµ are mean values of R and E
Rσ , Eσ are standard deviations of R and E
(6) For other formulations of the limit state equation or non-Normal distributions the reliability index can be determined by an iterative procedure and the probability of failure obtained approximately by (C.1).
NOTE: For calculation of the reliability index see ISO 2394 or
Probabilistic Model Code of JCSS [xx].
C.5.3 Time-variant reliability problems
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Background for recommendation.
(1) Two classes of time-dependent problems are considered, namely those associated with
– failures caused by extreme values, and – failures caused by the accumulation of effects
over time.
(2) In the case of failure due to extreme values, a single action process may be replaced by a random variable representing the extreme characteristics (minimum or maximum) of the random process over a chosen reference period, typically the life time or one year. If there is more than one stochastic process involved, they should be combined, taking into account the dependencies between the processes.
(3) An exact and general expression for the failure probability of a time varying process on a time interval (0,t) can be derived from integration of the conditional failure rate h(τ) according to:
0(0, ) 1 exp ( )
t
fP t h dτ τ = − − ∫ (C.3)
(4) The conditional failure rate is defined as the probability that failure occurs in the interval (τ, τ+dτ), given no failure before time τ. When the failure threshold is high enough it may be assumed that the conditional failure rate h(τ) can be replaced by the average out-crossing intensity ν (τ):
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Background for recommendation.
0
( ( ( )) 0 ( ( ) 0)( ) lim
P g X t g X ttν
∆→
> ∩ + ∆ ≤=∆
(C.4)
(5) If failure at the start (t = 0) explicitly is considered: P(0,t) = Pf(0) + [1 – Pf(0)] [1 – exp ] (C.5)
in which Pf(0) is the probability of structural failure at (t = 0). The mathematical formulation of the out-crossing rate ν depends on the type of loading process, the structural response and the limit state. For practical application the formula (C.5) may need to be extended to include several processes with different fluctuation scales and/or constant in time random variables. (6) In the case of cumulative failures (fatigue, corrosion etc.), the total history of the load up to the point of failure may be of importance. In such cases the time dependency may be accounted for by subdividing the considered time reference period into intervals and to model and calculate the probability of failure as failure of the logical series system comprised by the individual time intervals.
C.6 Target values of reliability index ββββ
(1) Target values for the reliability index β for various design situations, and for reference periods of 1 year and 50 years, are indicated in Table C2. The values of β in Table C2 correspond to levels of safety for reliability class RC2 (see Annex B) structural members. NOTE 1 For these evaluations of β − Lognormal or Weibull distributions have usually been used for material and structural resistance parameters and model uncertainties ;
(1) Decisions with respect to the design, repair, strengthening, maintenance, operation and decommissioning of structures should take basis in risk assessments, whereby it is ensured that benefits are optimized and at the same time that life safety risks are managed in accordance with society preferences. NOTE Risk assessment should performed in accordance with ISO 13824:2009 Bases for design of structures - general principles on risk assessment of systems involving structures.
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Background for recommendation.
− Normal distributions have usually been used for self-weight − For simplicity, when considering non-fatigue verifications, Normal distributions have been used for variable actions. Extreme value distributions would be more appropriate. NOTE 2 When the main uncertainty comes from actions that have statistically independent maxima in each year, the values of β for a different reference period can be calculated using the following expression
[ ]n
n )Φ()Φ( 1ββ = (C.3)
where βn is the reliability index for a reference period of n years,
design situations, and for reference periods of 1 year and 50 years
β1 is the reliability index for one year. Table C2 - Target reliability index ββββ for Class RC2 structural members 1)
Limit state Target reliability index Ultimate 1 year 50 years Fatigue 4,7 3,8 Serviceability (irreversible)
1,5 to 3,8
2,9 1,5 1) See Annex B 2) Depends on degree of inspectability, reparability and damage tolerance.
(2) The actual frequency of failure is significantly dependent upon human errors which are not considered in partial factor design (See Annex B). Thus β does not necessarily provide an indication of the actual frequency of structural failure.
(2) Risk based decision making should in principle include all consequences associated with the decisions, including consequences caused by structural failures but also in terms of the benefits achieved from the operation of the structures. The risk related to a decision a is in general
defined as ( ) ∑==
En
iii CPaR
1 where En is the number of
possible events with iP and iC being the probability and
the consequence associated with event i . The possible events arising out of the decision a should include all direct and indirect consequences for all phases of the life cycle of the structure. (3) The specified maximum acceptable failure probabilities should be chosen in dependency on the consequence and the nature of failure, the economic losses, the social inconvenience, and the amount of expense and effort required to reduce the probability of failure. If there is no risk of loss of human lives associated with structural failures the target failure probabilities may be selected solely on the basis of an economic optimization. If structural failures are associated with risk of loss of human lives the marginal life saving costs principle applies and this may be used through the Life Quality Index. In all cases the acceptable failure probabilities should be calibrated against well-established cases that are known from past experience to have adequate reliability. (4) The specified maximum failure probabilities relevant for ultimate and serviceability limit state design, should
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reflect the fact that criteria for such limit states do not account for human errors. These probabilities are not directly related to the observed failure rate, which is highly influenced by failures involving some effects of human errors. (5) When dealing with time-dependent structural properties, the effect of the quality control and inspection and repair procedures on the probability of failure should be taken into account. This may lead to adjustments to specified values, conditional upon the results of inspections. Specified failure probabilities should always be considered in relation to the adopted calculation and probabilistic models and the method of assessment of the degree of reliability. (6) Target values for the reliability index β for various design situations, and for reference periods of 1 year and 50 years, are indicated in Table C2. The values of β in Table C2 correspond to levels of safety for reliability class RC2 (see Annex B) structural members. Table C2 - Target reliability index ββββ for Class RC2 structural members 1)
Limit state Target reliability index Ultimate 1 year 50 years Fatigue 4,7 3,8 Serviceability (irreversible)
2,9 to 4,7 1,5 to 3,8
2,9 1,5 1) See Annex B 2) Depends on degree of inspectability, reparability and damage tolerance.
NOTE 1 For these evaluations of β
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Background for recommendation.
− Lognormal or Weibull distributions have usually been used for material and structural resistance parameters and model uncertainties ; − Normal distribution has usually been used for self-weight − Three parameter Lognormal distribution or extreme value distribution have usually been used for variable actions.
− Lognormal distribution is often used to model uncertainties related to fatigue loads.
NOTE 2 When the main uncertainty comes from actions that have statistically independent maxima in each year, the values of β for a different reference period can be calculated using the following expression
[ ]n
n )Φ()Φ( 1ββ = (C.6)
where βn is the reliability index for a reference period of n years, β1 is the reliability index for a reference period of one year. (7) The actual frequency of failure is significantly dependent upon human error which is not considered in partial factor design (See Annex B). Thus β does not necessarily provide an indication of the actual frequency of structural failure.
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Background for recommendation.
C7 Approach for calibration of design values
(S) failure boundary g = R – E = 0
P design point
Figure C2 - Design point and reliability index ββββ according to the first order reliability method
(FORM) for Normally distributed uncorrelated variables).
(2) Design values should be based on the values of the basic variables at the FORM design point, which can be defined as the point on the failure surface (g = 0) closest to the average point in the space of normalised variables (as diagrammatically indicated in Figure C2). (3) The design values of action effects Ed and resistances Rd should be defined such that the probability of having a more unfavourable value is as follows: P(E > Ed ) = Φ (+αEβ) (C.6a)
C7.1 Basis for calibration of design values (1) The reliability elements including partial factors γ and ψ factors should be calibrated in such a way that the target reliability index βt is best achieved. The calibration procedure (see Fig. C.2) follows several steps:
a. Selection of a set of reference structures b. Selection of a set of reliability elements (e.g. partial
factors, ψ factors) c. Designing the structures according to the selected set
of reliability elements d. Calculation the reliability indices for the designed
structures
e. Calculation the difference D = ∑ wi (βi – βt)2 (wi is the
weight factor i)
f. Repeating steps (b) to (f) for getting minimum value of difference D
NOTE: The choice of the target value of reliability index βt should be based on optimisation procedure. Different values of reliability index βt may be needed for different failure modes.
(2) The set of partial factors and ψ factors that leads to the lowest value of D is the desired set. More detail procedure how to provide this optimisation is described in several sources (e.g. in ISO 2394). The probabilistic models for loads and resistances of the JCSS Probabilistic Model Code [xx] may be used.
Need for explanation of basis of calibration of reliability elements is based on requests of users.
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P(R ≤ Rd ) = Φ (-αRβ) (C.6b) where βn is the target reliability index (see C6) αE and αR, with |α| ≤ 1, are the values of the FORM sensitivity factors. The value of α is negative for unfavourable actions and action effects, and positive for resistances. αE and αR may be taken as - 0,7 and 0,8, respectively, provided 0,16 < σE/σR < 7,6 (C.7) where σE and σR are the standard deviations of the action effect and resistance, respectively, in expressions (C.6a) and (C.6b). This gives P(E > Ed ) = Φ(-0,7β) (C.8a) P(R ≤ Rd ) = Φ(-0,8β) (C.8b) (4) Where condition (C.7) is not satisfied α = ± 1,0 should be used for the variable with the larger standard deviation, and α = ± 0,4 for the variable with the smaller standard deviation where σE and σR are the standard deviation. (5) When the action model contains several basic variables, expression (C.8a) should be used for the leading variable only. For the accompanying actions the design values may be defined by
Figure C2 Illustration of a calibration procedure of
reliability elements. C7.2 The design value method (1) The design value method is directly linked to the basic principle of EN 1990 according to which it should be verified that no limit state is exceeded when the design values of all basic variables are used in the models of structural resistance R and action effects E. A design of a structure is considered to be sufficient if the limit states are not reached when the design values are introduced into the models. In symbolic notation this is expressed as Ed < Rd (C.7) where the design values of action effect Ed and resistance Rd are given as Ed = E{Fd1,Fd2, … ad1, ad2,.. θd1, θd2, …} (C.8a) Rd = R{Xd1,Xd2, … ad1, ad2,.. θd1, θd2, …} (C.8b)
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P (E > Ed) = Φ (-0,4×0,7×β) = Φ (-0,28β) (C.9) NOTE For β = 3,8 the values defined by expression (C.9) correspond approximately to the 0,90 fractile. (6) The expressions provided in Table C3 should be used for deriving the design values of variables with the given probability distribution. Table C3 – Design values for various distribution functions
Distribution Design values Normal αβσ−µ
Lognormal )Vexp(µ αβ− for V = σ/µ < 0,2
Gumbel )}(-ln{-ln
a -u αβΦ1
where
6
5770
σπ=−µ= a;
a
,u
NOTE In these expressions µ, σ and V are, respectively, the mean value, the standard deviation and the coefficient of variation of a given variable. For variable actions, these should be based on the same reference period as for β. (7) One method of obtaining the relevant partial factor is to divide the design value of a variable action by its representative or characteristic value.
where Fd is the design value of action Xd is the design value of resistance property ad is the design value of geometrical property θd is the design value of model uncertainty. (2) For some particular limit states (e.g. fatigue) a more general formulation may be necessary to express a limit state. (3) If only two basic variables E and R are considered then the design values of action effects Ed and resistances Rd should be defined such that the probability of having a more unfavourable value is as follows FE(ed) = Φ(+αEβt) (C.9a) FR(rd) = Φ(–αEβt) (C.9b) where Φ is the cumulative distribution function of the
standardised Normal distribution βt is the target reliability index with reference period T
(see C6) αE and αR, with |α| ≤ 1, are the values of the FORM sensitivity factors for action and for resistance. The value of α is negative for unfavourable actions and action effects, and positive for resistances. (4) In common cases the coefficients of sensitivity for leading unfavourable actions and action effects αE = -0,7 and αE = -0,28 for accompanying unfavourable actions may be taken and the coefficient of sensitivity for resistance αR = 0,8 provided that the ratio between standard deviations of the load effect σE and resistance σR is in a range
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0,16 <σE/σR < 7,6 (C.10) NOTE 1 Where condition (C.10) is not satisfied, α = ± 1,0 should be used for the variable with the larger standard deviation, and α = ± 0,4 for the variable with the smaller standard deviation.
NOTE 2 For αE = -0,28 the values defined by expression (C.9) correspond approximately to the 0,90 fractile. (5) The design value Fd of the action and resistance Rd may be expressed from (C.9) as Fd(βt) = FF
-1[Φ(–αEβt)] (C.11a) Rd(βt) = FR
-1[Φ(+αRβt)] (C.11b) where F(.)-1 is an inverse cumulative distribution function. (6) The expressions provided in Table C3 should be used for deriving the design values of variables with the given probability distribution. Table C3 – Design values for various distribution functions
Distribution Design values Normal αβσ−µ
Lognormal )exp( Vµ αβ− for V = σ/µ < 0,2
Gumbel )}(ln{-ln
1 αβΦ - a
-u
where 6
5770
σπ=−µ= a;
a
,u
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Weibull 11 ))(ln(Φ 12sup
cc cx − −− −−− β
where xsup = µ + up σ
)c
c()
c
c(
)c
c(
u
c
p
1
12
1
1
1
1
1
1Γ
2Γ
))(ln(Φ1
Γ 1
+−+
−−−+
=
− β
NOTE In these expressions µ, σ, V and a are, respectively, the mean value, the standard deviation, the coefficient of variation and the skewness of a given variable. For variable actions, these should be based on the same reference period as for β. (7) One method of obtaining the relevant partial factor is to divide the design value of a variable action by its representative or characteristic value. C7.3 Material partial factors (1) The resistance model is assumed to be obtained by the following general model, see Annex D:
)R( a,XbR δ= (C.12)
where
)R( a,X is the resistance model as defined in a relevant
materials standard X is strength (and stiffness) parameter(s). Each of the
strength parameters is modelled as a Lognormal stochastic variable with coefficient of variation VX.
a is the geometrical parameter(s) δ is the model uncertainty related to resistance model
(can be determined using the method in the Annex D ‘Design assisted by testing’). δ is modelled as a Lognormal stochastic variable with mean value 1 and coefficient of variation δV
b is bias in resistance model (can be determined using
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the method in the Annex D ‘Design assisted by testing’).
(2) The design value of the resistancedR can be
determined by different models, see Cl. 6.3.5. (3) Model 1 where design values are determined for the material strength parameters
∆
dd ),R(
γaX
Rd = (C.13)
where ad is the design value for geometrical data. Xd is the design value for strength parameters
∆γ is the partial factor related to the model uncertainty for
the resistance model – including possible uncertainty related to transformation from laboratory to real structure and bias in resistance model.
If more than one strength parameter is used in the resistance model, then design values are applied for each strength parameter in (4). (4) The design value of a strength parameter(s)dX is
determined by
m
kd γ
η XX = (C.14)
where η is the conversion factor taking into account load
duration effects, moisture, temperature, scale effects,
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etc. Xk is the characteristic value of strength parameter
generally defined by the 5% fractile
mγ is the partial factor for strength parameter depending
on the coefficient of variation XV , see Table C4.
NOTE If the resistance model is linear in the strength parameters then )R( ddd a,XR = and dX for each of the strength
parameters is obtained using a partial factor ∆mM γγγ = .
(5) Model 2 where a characteristic resistance is obtained using characteristic values of the material strength parameters
M
kk ) (
γη a,XR
Rd = (C.15)
where γM is the partial factor related to uncertainty of the
strength parameters X through the resistance function R(X,a), VR.
(6) Model 3 where a characteristic resistance is estimated based on tests
M
kd γ
RR = (C.16)
where Rk is the characteristic resistance estimated based on tests,
see the Annex D ‘Design assisted by testing’. kR is
generally defined by the 5% fractile γM is the partial factor related to uncertainty of the
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resistance obtained based on tests, RV .
(7) In model 1 the partial factor mγ depends on the
uncertainty of the strength parameter(s) and ∆
γ depends
on the uncertainty of the resistance model, incl. bias
bδγγ =
∆ (C.17)
where γδ is partial factor depending on the model uncertainty
with coefficient of variation δV , see Table C5.
(8) In model 2 the total uncertainty of the resistance depends on the model uncertainty δ and the uncertainty related to the strength parameters X though the resistance function )( a,XR . The material partial factors are
correspondingly obtained from
bRγγγ δ=M (C.18)
where γR is partial factor depending on the resistance uncertainty
with coefficient of variation RV . Coefficient RV
depends on the uncertainties of the strength parameters though the resistance function )a,X(R , see Table C4
δγ is partial factor depending on the model uncertainty
with coefficient of variation δV .
(9) In model 3 the partial factor Mγ depends on the
uncertainty of the test results including statistical uncertainty
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Rγγ =M (C.19)
where γR is partial factor depending on the resistance uncertainty
with coefficient of variation RV . Coefficient RV
depends on the uncertainties of the resistance obtained based on tests, see Table C4.
(10) The material partial factors in Tables C4 and C5 should be calibrated such that failure probabilities for the relevant failure modes are close to the target reliability level in Table C5. (11) The material partial factors for ultimate limit states in the persistent and transient design situations should be in accordance with Tables C4 and C5. NOTE 1 The values in Tables C4 and C5 can be altered e.g. for different reliability levels in the National annex. NOTE 2 The partial factors in Tables C4 and C5 are calibrated without taking into account the bias b and with the characteristic value for the model uncertainty equal to 1. Table C4 mγ , Rγ - partial safety factor for strength
parameter or resistance. Coefficient of variation for strength parameter in model 1,
XV or resistance in
model 2 and 3, RV
≤5 % 10 % 15 % 20 % 25 %
mγ in model 1 or Rγ
in model 2 and 3
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Table C5 δγ - partial safety factor for model uncertainty.
Coefficient of variation for model uncertainty for resistance model in model 1, δV
≤5 % 10 % 15 % 20 % 25 %
δγ
C7.4 Partial factors of actions (1) The partial factors of actions may be determined using the design value method. For a specific load case where material properties are not to be considered, the design values of the effects of actions Ed (exp. (6.2) in EN 1990) may be expressed as:
{ } 1E drepd ≥= ia;FE i,i,fSd γγ (C.20)
where ad is the design value of the geometrical data γSd is a factor for model uncertainties in modelling the
effects of actions or in particular cases, in modelling the actions.
(2) The design effects of actions may be commonly simplified for the design of common structures (exp. (6.2a, 6.2b) in EN 1990):
{ } 1≥= ia;FEE di,repi,Fd γ (C.21)
where
i,fSi,F γγγ ×= d (C.22)
NOTE Further guidance is given for non-linear structural analyses.
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(3) The partial factor of action F is based on the ratio between the design value Fd and the characteristic value Fk of an action given as γF = Fd /Fk (C.23) C7.4.1 Partial factors of permanent actions (1) Characteristic value of a permanent action Gk may be commonly considered as a mean value (see EN 1991-1-1) based on nominal values of geometry and mean densities, therefore Gk = µG. (2) In case that the variability of permanent action is greater than 5 %, or it is important to take into account this variability, it should be considered by 5% lower and 95% upper fractiles. NOTE Normal distribution for permanent actions may be commonly applied. The lower and upper fractiles of the permanent action may be specified as Gk,inf = µG – 1,64 σG = µG (1 – 1,64 VG) Gk,inf = µG + 1,64 σG = µG (1 + 1,64 VG) where VG is the coefficient of variation µG is the mean σG is the standard deviation. (3) The design value of the permanent action Gd may be determined as Gd = µG − αG β σG = µG (1 + 0,7β VG) (C.24)
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(4) The partial factor for self-weight γg is given as the ratio between the design and characteristic values γg = Gd / Gk = µG (1 − αG β VG)/ µG = 1 − αG β VG (C.25) where VG is the coefficient of variation of permanent action. In
common cases the coefficient of variation of self-weight of a structure (e.g. concrete, steel) may be assumed to be from 3 to 5 %. For other permanent actions the coefficient of variation is commonly higher, up to 10 %.
Example:
In case that the coefficient of variation VG = 0,05 is assumed for self-weight of a structure and the self-weight is a leading action (expressions (6.10) or (6.10a)) in the fundamental combination of actions in EN 1990), then for the coefficient of sensitivity αG = – 0,7 and the target value of reliability index βt = 3,8, the partial factor is determined as
γg = 1 − αG β VG = 1 + 0,7 × 3,8 × 0,05 ≈ 1,15
If the self-weight is a non-dominant action (αG = – 0,28), see expression (6.10b), the partial factor can be determined as
γg = 1 + 0,28 × 3,8 × 0,05 = 1,05
It should be noted that the coefficient γsd for model uncertainties should also be taken into account which is commonly in a range from 1,05 to 1,15. In case that the coefficient for model uncertainties γsd = 1,1 is considered then the partial factor γG for a leading permanent action is given as
γG = 1,15 × 1,1 ≈ 1,27
and for an accompanying permanent action
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γG = 1,05 × 1,1 ≈ 1,16
C7.4.2 Partial factors for variable actions (1) Similar procedure may be applied for estimation of partial factors for variable actions Q. Commonly lognormal distribution, Gamma or extreme value distribution may be apply for modelling of variable actions including climatic actions. (2) The characteristic values of a climatic actions (wind, snow, icing, temperature) are specified according to EN 1990 in a way that the annual probability of their exceeding should be 0,02 (mean return period of 50 years). NOTE In some cases, e.g. in phases of transient design situation and depending on the character of loading it may be more suitable to use other probability p or other return period (see e.g. EN 1991-1-6 for transient design situations and shorter periods of execution). (3) In case that the Gumbel distribution should be applied (which is recommended in some Parts of EN 1991), then the p-fractile of a climatic action Q for a certain reference period is given as Qp = µQ {1 − VQ [0,45 – 0,78lnN + 0,78 ln(−lnp)]} (C.26) where VQ denotes the coefficient of variation of climatic action for the basic period (e.g. 1 year) and N is the number of basic periods during the reference period (often the assumed working life of a structure, e.g. 100 years for a bridge). (4) The characteristic value of a climatic action (e.g for p = 0,98 in the basic reference period) may be determined as
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Qk = µQ {1 − VQ [0,45 + 0,78 ln(−ln0,98)]} (C.27) and the design value of action Qd = µQ{1 − VQ [0,45 – 0,78lnN + 0,78 ln(−ln(Φ-1(–αEβ))]} (C.28) where Φ is the standard Normal distribution function β is the reliability index corresponding to the reference period αE is the FORM coefficient of sensitivity being 0,7 for dominant and 0,28 for non-dominant loads N is the number of basic periods in the reference period (e.g. N = 100 if the design life time is 100 years and the basic period 1 year). Note that sometimes p is chosen dependently on the design life time. (5) The partial factor of a climatic action is based on the expressions (C.29) and (C.30)
γq = ))980lnln(780450(1
)))(ln(Φln(780ln780450(1 1
,,,V
,N,,V
Q
EQ
−+−−−+−− − βα
(C.29) under the assumption of a Gumbel distribution. NOTE 1 In some cases other probabilistic distributions may be more suitable, e. g. Weibull or three parameter lognormal distributions. NOTE 2 Direct application of the three parameter or Lognormal or extreme value probabilistic distributions for specification of partial factors for climatic actions (e.g. snow, wind) commonly leads to greater values of partial factors than recommended in Eurocodes. However, commonly a hidden safety may be found
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Background for recommendation.
based on several factors (see e.g. the Background document to EN 1990).
C7.5 Calibration of partial factors for fatigue (1) The SN-approach is used together with the Miner’s rule for linear fatigue accumulation. NOTE Fatigue failure of welded details is considered in this clause. The same principles can be used for fatigue failure of other fatigue critical details. (2) For linear SN-curves the number of cycles, N to failure with constant stress range, σ∆ is:
( ) m
m
C
KN −
−
⋅=⋅
= σ
σσσ ∆102
∆
∆∆
6 (C.30)
where
C∆σ is the characteristic fatigue strength defined as the
5% quantile m is the slope of SN-curve (Wöhler exponent) K is the SN-curve parameter (3) For variable amplitude fatigue loading the design value of the Miner’s sum should fulfil:
1∆
∆
102 6≤∑
⋅i
m
MfC
iFfi
/
n
γσσγ
(C.31)
where
γMf is the partial factor for fatigue strength
γFf is the partial factor for fatigue load ni is the number of cycles with fatigue stress range
iσ∆
(4) For non-linear SN-curves the design value of the
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Background for recommendation.
Miner’s sum should fulfil:
( ) 1∆
≤∑i
iFfMf
i
N
n
σγγ (C.32)
(5) The partial factor for fatigue strength Mfγ is obtained
from:
fMMfMf 0γλγ ⋅= (C.33)
where
γM0f is the partial factor for fatigue strength depending on uncertainties related to the SN-curve and the Miner’s rule
λMf is the factor accounting for bias and other fatigue strength uncertainties not included in fM 0γ , such as
scales and temperature effects. (6) The partial factor for fatigue load Ffγ is obtained from:
fFFfFf 0γλγ ⋅= (C.34)
where
γM0f is the partial factor for fatigue stress depending on uncertainties related to fatigue load and stress assessment
λMf is the factor accounting for bias and other fatigue stress uncertainties not included in fF 0γ such as
different load spectra. (7) The partial factors fM 0γ and fF 0γ in Tables C5 and C6
are calibrated such that failure probabilities for the relevant
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Background for recommendation.
failure modes are close to the target reliability level in Table C2. The partial factor fM 0γ depends on the
coefficient of variations KlV og for the fatigue strength
parameter, logK and ∆
V for the Miner’s sum. The partial
factor fF 0γ depends on the coefficient of variation, FfV for
the fatigue load and stress. NOTE 1 The values in Tables C5 and C6 can be altered e.g. for different reliability levels in the National annex. NOTE 2 The values in Tables C5 and C6 can be altered depending on consequences of failure and the associated target reliability. NOTE 3 The values in Tables C5 and C6 can be altered if inspections are performed depending on the reliability of the inspection method using a POD (Probability Of Detection) curve and a fracture mechanics approach to fatigue crack growth. NOTE 4 The fatigue strength parameter, logK can be assumed Normal distributed with VlogK depending on the actual SN-curve. The Miner sum can be assumed Lognormal distributed with V∆ ≈ 0 for constant amplitude loading and V∆ ≈ 0,3 for variable amplitude loading. The uncertainty for the fatigue stress ranges can be assumed Lognormal distributed with a factor representing uncertainty for the fatigue load and a factor representing uncertainty for the calculation of stress ranges given fatigue loading. The coefficient of variation for uncertainty related to fatigue loading from e.g. rotating machines can be assumed ≈ 0 whereas for fatigue loading from e.g. wind induced vortex shedding it can be assumed ≈ 0,3. Table C6. fM 0γ - partial factor for fatigue strength.
Coefficient of variation, VlogK for fatigue strength parameter, logK
≤ 10 % 20 % 30 %
fM 0γ for ∆
V = 0 %
fM 0γ for ∆
V = 30 %
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Background for recommendation.
Table C7. fF 0γ - partial factor for fatigue stress.
Coefficient of variation,
FfV for fatigue
stress
≤5 % 10 % 15 % 20 % 25 % 30 %
fF 0γ
C9 Partial
factors in EN
1990
Figure C3 – Relation between individual partial factors
C10 0
factors
Expression for general distribution in Table C4 for ψo for the case of two variable actions
{ }{ }1
1
70
401
1
N
s
N
s
),(F
)',(F
βΦβΦ
−
−
Expression in Table C8 for ψo for the case of two variable actions
{ }{ }1
1
70
401
1
N
s
N
s
)',(F
)',(F
βΦβΦ
−
−
Uncertainty in representative values of
Model uncertainty in actions and action
Model uncertainty in resistance, bias in resistance model (see Annex D)
Uncertainty in basic variables describing resistance
γf
γSd
γRd
γm
γM
γF
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Appendix 1 PROPOSAL FOR THE MINIMUM CONTENTS OF THE STRUCTURAL DESIGN REPORT
2.x Structural Design Report (1)P The assumptions, data, methods of calculation, and results of the verification of safety and serviceability shall be recorded in the Structural Design Report. (2)P If appropriate, the Structural Design Report shall include a plan of supervision and monitoring. Items that require checking during construction or require maintenance after construction shall be clearly identified in the Structural Design Report. When the required checks have been carried out during construction, they shall be recorded in an addendum to the Structural Design Report. (3)P An extract from the Structural Design Report, containing the supervision, monitoring and maintenance requirements for the completed structure, shall be provided to the owner/client. The following to go into Information Annex
The following is proposed for an Information Annex to EN 1990
Annex x Structural Design Report (1) The level of detail of Structural Design Reports will vary greatly, depending on the type of design. For simple designs, a single sheet may be sufficient. (2) The Structural Design Report should normally include the following items, with cross-reference to the Geotechnical Design Report and to other documents, which contain more detail:
— a description of the project and constraints; — a description of the proposed construction, including actions; — design values of material properties, including justification, as appropriate; — statements on the codes and standards applied; — statements on the suitability of the proposed construction and the level of acceptable risks; — structural design calculations and drawings; — structural design recommendations; — a note of items to be checked during construction or requiring maintenance or monitoring. — <any others to be added? >
(3) In relation to supervision and monitoring, the Structural Design Report should state the:
— purpose of each set of observations or measurements;
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— parts of the structure that are to be monitored and the locations at which observations are to be made; —frequency with which readings are to be taken; —ways in which the results are to be evaluated; —range of values within which the results are to be expected; —period of time for which monitoring is to continue after construction is complete; —parties responsible for making measurements and observations, for interpreting the results obtained and for maintaining the instruments.
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Appendix 2 PROPOSAL FOR THE ULS VERIFICATIONS FORMAT STR/EQU/GEO
(more appropriate for structures below ground)
Clause EN 1990:2002 + A1:2004 incorporating corrigenda
December 2008 and April 2010
Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause
Background for recommendation
3.3 Ultimate limit states
3.3(4)P The following ultimate limit states
shall be verified where they are
relevant :
– loss of equilibrium of the
structure or any part of it,
considered as a rigid body ;
– failure by excessive deformation,
transformation of the structure or
any part of it into a mechanism,
rupture, loss of stability of the
structure or any part of it, including
supports and foundations ;
– failure caused by fatigue or other
time-dependent effects.
NOTE Different sets of partial
factors are associated with the
various ultimate limit states, see
6.4.1. Failure due to excessive
deformation is structural failure
due to mechanical instability.
The following ultimate limit states shall be verified where they are
relevant:
– failure by excessive deformation, transformation of the structure or
any part of it into a mechanism, rupture, loss of stability of the structure
or any part of it, including supports and foundations;
– failure or excessive deformation of the ground where the strengths of
soil or rock are significant in providing resistance ;
– loss of equilibrium of the structure or any part of it, considered as a
rigid body;
– loss of equilibrium of the structure or the ground due to uplift by water
pressure (buoyancy) or other vertical actions;
– hydraulic heave, internal erosion and piping in the ground caused by
hydraulic gradients;
– failure caused by fatigue or other time-dependent effects.
NOTE Different sets of partial factors are associated with the various
ultimate limit states, see 6.4.1. Failure due to excessive deformation is
structural failure due to mechanical instability.
1) More comprehensive
list of limit states
2) more logical order,
corresponding to
designer’s typical order
of checking
3) Note is redundant
with new formulation in
6.4.1
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Background for recommendation
6.4.1 General
6.4.1(1)P
The following ultimate limit states shall be verified
as relevant :
a) EQU : Loss of static equilibrium of the structure or
any part of it considered as a
rigid body, where :
– minor variations in the value or the spatial
distribution of permanent actions from a
single source are significant, and
– the strengths of construction materials or ground
are generally not governing ;
b) STR : Internal failure or excessive deformation of
the structure or structural members,
including footings, piles, basement walls, etc., where
the strength of construction
materials of the structure governs ;
c) GEO : Failure or excessive deformation of the
ground where the strengths of soil or
rock are significant in providing resistance ;
d) FAT : Fatigue failure of the structure or structural
members.
NOTE For fatigue design, the combinations of
actions are given in EN 1992 to EN 1995, EN 1998
and EN
1999.
The following ultimate limit states shall be verified as
relevant:
a) STR: Internal failure or excessive deformation of the
structure or structural members (including footings, piles,
basement walls, etc.), where the strength of construction
materials provides significant resistance;
b) GEO: Failure or excessive deformation of the ground,
where the strength of the ground provides significant
resistance;
c) EQU: Loss of static equilibrium of the structure or any
part of it considered as a
rigid body, where the strengths of construction materials
and the ground do not provide significant resistance;
d) Combined STR+EQU: Loss of static equilibrium of the
structure or any part of it considered as a rigid body, where
the strengths of construction materials provide significant
resistance;
e) Combined GEO+EQU: Loss of static equilibrium of the
structure or any part of it considered as a rigid body, where
the strength the ground provides significant resistance;
f) UPL: loss of equilibrium of the structure or the ground
due to uplift by water
pressure (buoyancy) or other vertical actions;
g) HYD: hydraulic heave, internal erosion and piping in the
ground caused by hydraulic
gradients;
h) FAT: Fatigue failure of the structure structural members.
1) More logical
ordering of limit states
2) introduced
combined limit states
STR+EQU and
GEO+EQU
3) use phrease
‘significant resistance’
as discriminator
between EQU, STR,
GEO and combined
limit states
4) simplify ‘soil and
rock’ to ‘ground’
(consistent with EN
1997)
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Background for recommendation
6.4.1(1)P
(continue)
e) UPL : loss of equilibrium of the structure or the
ground due to uplift by water
pressure (buoyancy) or other vertical actions ;
NOTE See EN 1997.
f) HYD : hydraulic heave, internal erosion and piping
in the ground caused by hydraulic
gradients.
NOTE See EN 1997.
6.4.2 Verifications of static equilibrium and resistance
6.4.2(1) When considering a limit state of static equilibrium
of the structure (EQU), it shall be
verified that :
Ed ,dst ≤ Ed ,stb (6.7)
where :
Ed ,dst is the design value of the effect of
destabilising actions ;
Ed ,stb is the design value of the effect of stabilising
actions.
When considering limit states STR+EQU and GEO+EQU, it
shall be verified that:
(6.7)
where:
Ed is the design value of the effect of unfavourable actions;
Ed ,fav is the design value of the effect of favourable
actions; and
Rd is the design value of the corresponding resistance.
1) Introduce more
generic expression to
cover main limit states
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Background for recommendation
6.4.2(2) (2) Where appropriate the expression for a limit
state of static equilibrium may be
supplemented by additional terms, including, for
example, a coefficient of friction between
rigid bodies.
(2) When the strengths of construction materials and the
ground do not provide significant resistance (i.e. limit state
EQU), expression (6.7) reduces to:
(6.8)
where:
Ed,dst (= Ed in expression 6.7) is the design value of the
effect of destabilising (i.e. unfavourable) actions; and
Ed,stb (= Ed,fav in expression 6.7) is the design value of the
effect of stabilising (i.e. favourable) actions.
1) Simplification that
reduces to ‘pure’ EQU
6.4.2(3)P When considering a limit state of rupture or
excessive deformation of a section,
member or connection (STR and/or GEO), it shall be
verified that :
Ed ≤ Rd (6.8)
where :
Ed is the design value of the effect of actions such as
internal force, moment or a vector
representing several internal forces or moments ;
Rd is the design value of the corresponding
resistance.
When favourable effects of actions are insignificant in
comparison with the resistance (limit states STR and GEO),
expression (6.7) reduces to:
(6.9)
1) Simplification that
reduces to ‘pure’ STR
and GEO
6.4.2(NOTE
1)
NOTE.1 Details for the methods STR and GEO are
given in Annex A.
NOTE.1 Partial factors for limit states STR+EQU, GEO+EQU,
STR, GEO, and EQU are given in Annex A.
Updated list according
the list of limit states
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Background for recommendation
6.4.2(NOTE
2)
NOTE 2 Expression (6.8) does not cover all
verification formats concerning buckling, i.e.
failure that happens where second order effects
cannot be limited by the structural response, or
by an acceptable structural response. See EN
1992 to EN 1999.
NOTE 2 Expressions (6.7) and (6.9) do not cover all verification
formats concerning buckling, i.e. failure that happens where
second order effects cannot be limited by the structural
response, or by an acceptable structural response. See EN 1992
to EN 1999.
Updated cross
reference to
expressions
A1.3.1 Design values of actions in persistent and transient design situations
A1.3.1(1)-
(7)
Changes to be agreed Needs review once
contents of Tables
have been agreed
Table
A1.2(A)
Table A1.2(A) - Design values of actions (EQU)
(Set A)
Permanent actions Accompanying
variable actions
Persistent
and
transient
design
situations
Unfavourable Favourable
Leading
variable
action
Main (if
any)
Others
(6.10) γG,j,supGk,j,sup γG,j,infGk,j,inf γQ,1Qk,1 γQ,iψ0,iQk,i
(6.10a) γG,j,supGk,j,sup γG,j,infGk,j,inf γQ,1ψ0,1
Qk,1
γQ,iψ0,iQk,i
(6.10b) ξγG,j,supGk,j,sup γG,j,infGk,j,inf γQ,1Qk,1 γQ,iψ0,iQk,i
Combine Tables
A1.2(A) and (B)
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Background for recommendation
Table
A1.2(A)
NOTE 1
NOTE 1 The γvalues may be set by the National
annex. The recommended set of values for γ are :
γG,j,sup = 1,10
γG,j,inf = 0,90
γQ,1 = 1,50 where unfavourable (0 where
favourable)
γQ,i = 1,50 where unfavourable (0 where
favourable)
NOTE 1 Two separate verifications are required using partial
factors from Set 1 and Set 2. The γ values may be set by the
National annex.
Two verifications
(called Sets 1 and 2)
are strictly necessary
to check STR, GEO,
EQU, and their
combinations
Best NOT to associate
these sets of partial
factors with specific lit
states
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Background for recommendation
Table
A1.2(A)
NOTE 2
NOTE 2 In cases where the verification of static
equilibrium also involves the resistance of
structural
members, as an alternative to two separate
verifications based on Tables A1.2(A) and A1.2(B),
a combined verification, based on Table A1.2(A),
may be adopted, if allowed by the National
annex, with the following set of recommended
values. The recommended values may be altered
by the National
annex.
γG,j,sup = 1,35
γG,j,inf = 1,15
γQ,1 = 1,50 where unfavourable (0 where
favourable)
γQ,i = 1,50 where unfavourable (0 where
favourable)
provided that applying γG,j,inf = 1,00 both to the
favourable part and to the unfavourable part of
permanent actions does not give a more
unfavourable effect.
NOTE 2 The recommended values of γ for Set 1 are:
γG,j,sup = 1,35
γG,j,inf = 1,10
γQ,1 = 1,50 where unfavourable (0 where favourable)
γQ,i = 1,50 where unfavourable (0 where favourable)
[The recommended values of γ for Set 2 are:
γG,j,sup = 1,35
γG,j,inf = 1,35
γQ,1 = 1,50 where unfavourable (0 where favourable)
γQ,i = 1,50 where unfavourable (0 where favourable)] – see
background for omitting Set 2
Set 2 could be omitted
if completely and two
verification could then
be made on basis of
that the ‘single-source
principle’ applied in
one verification and
not in the other
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Appendix 3 BACKGROUND CALCULATIONS EQU/STR
This Appendix includes some background calculations to verify the consistency of
formulations for EQU and combined EQU/STR verification according the proposed set of
partial factors.
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Appendix 4 PROPOSAL FOR THE AMENDMENT OF TABLE A1.2(B)
This Appendix to Annex A1 includes the proposal, to be discussed, for a revised table A1.2(B)
Table A1.2(B) - Design values of actions (STR/GEO) (Set B)
Persistent and transient
design situations
Permanent actions Leading variable action
Accompanying variable actions (*)
Persistent and transient
design situations
Permanent actions Leading variable
action (*)
Accompanying variable actions (*)
Unfavourable Favourable Main (if any)
Others Unfavourable Favourable Action Main Others
(Eq. 6.10) γGj,supGkj,sup
γGj,infGkj,inf
γQ,1Qk,1 γQ,iψ0,iQk,i
(Eq. 6.10a) γGj,supGkj,sup
γGj,infGkj,inf
γQ,1ψ0,1Qk,1 γQ,iψ0,iQk,i
(Eq. 6.10b) ξγGj,supGkj,sup
γGj,infGkj,inf
γQ,1Qk,1
γQ,iψ0,iQk,i
(*) Variable actions are those considered in Table A1.1 NOTE 1 The choice between 6.10, or 6.10a and 6.10b will be specified in the National annex. In case of 6.10a and 6.10b, the National annex may in addition modify 6.10a to include permanent actions only. NOTE 2 The γ and ξ values may be set by the National annex. The following values for γ and ξ are recommended for unfavourable actions (for favourable variable actions γQ = 0) when using expressions 6.10, or 6.10a and 6.10b γGj,sup = 1,35 (for the self-weight and permanent actions with low coefficient of variation up to 0,05 the values of partial factors γGj,sup may decreased up to 1,2) γGj,inf = 1,00 γQ = 1,3 to 1,5 for imposed loads (γQ = 1,5 for q < 2 kN/m2, γQ = 1,4 for 2 ≤ q < 5 kN/m2, γQ = 1,3 for q ≥ 5 kN/m2) γSn = 1,5 to 1,8 for snow γW = 1,5 to 1,7 for wind γT = 1,3 to 1,4 for temperatures where the decision on the values of partial factors for climatic actions should be based on appropriate probabilistic distribution and statistical characteristics, and for the coefficient ξ = 0,85 (so that ξγGj,sup = 0,85 × 1,35 ≅ 1,15 with a lower bound 1,05). See also EN 1991 to EN 1999 for γ values to be used for imposed deformations. NOTE 3 The characteristic values of all permanent actions from one source are multiplied by γG,sup if the total resulting action effect is unfavourable and γG,inf if the total resulting
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action effect is favourable. For example, all actions originating from the self-weight of the structure may be considered as coming from one source ; this also applies if different materials are involved.
NOTE 4 For particular verifications, the values for γG and γQ may be subdivided into γg and γq and the model uncertainty factor γSd. A value of γSd in the range 1,05 to 1,15 can be used in most common cases and can be modified in the National annex.
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Appendix 5 - ALTERNATIVE PROPOSAL BY WOLFRAM JÄGER FOR ANNEX B
Annex B (informative) Attainment of Structural Reliability and Checks for Design
and Execution of Construction Works
B.1. Scope and field of application
(1) This annex provides additional guidance to 2.2 Attainment of reliability and to 2.5 Checking management. The aim is to allow for an adequate choice of reliability and the necessary checking and supervision depending of the consequences of failure and the structural complexity.
NOTE Reliability differentiation rules have been specified for particular aspects in the design Euro- codes, e.g. in EN 1992 to EN 1999.
(2) The approach given in this annex recommends the following procedures for the attainment of structural reliability for construction works
a) In relation to 2.2(5) a), classes are introduced and are based on the assumed consequences of failure and the exposure of the construction works to hazard. A procedure for allowing moderate differentiation in the partial safety factors for actions corresponding to the classes is given in B.5.
NOTE Reliability classification can be represented by target levels of β indexes (see Annex C) which takes account of accepted or assumed statistical variability in action effects and resistances and model uncertainties.
b) In relation to 2.2(5) c) and 2.2(5) d), a procedure for allowing differentiation between various types of structures in the requirements for check levels for the design and inspection levels for execution process is given in B.11.
NOTE Those check management and control measures in design, detailing and execution given in B.8 and B.10 aim to eliminate failures due to essential human errors, and to ensure the resistances assumed in the design.
(3) The procedure has been formulated in such a way that it produces a framework that allows different reliability levels to be used, if desired.
B.2. Symbols
In this annex the following symbols apply.
KFI Factor applicable to actions for reliability differentiation
β Reliability index
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B.3. Consequences classes
(4) For the purpose of reliability differentiation, consequences classes (CC) may be established by considering the consequences of failure or malfunction of the structure as given in Table B.1.
Table B.1 Definition of consequences classes
Consequences Class
Description Examples of buildings and civil engineering works
CC3 High consequence for loss of human life, or very great economic, social or environmental consequences
Grandstands, public buildings and infrastructure elements where the consequences of failure are high
CC2 Moderate consequence for loss of human life, and considerable economic, social or environmental consequences
Residential and office buildings, public buildings where the consequences of failure are moderate
CC1 Low consequence for loss of human life, and small or negligible economic, social or environmental consequences
Agricultural buildings not normally occupied
(5) The criterion for classification of consequences is the importance, in terms of consequences of failure, of the structure or structural member concerned. See B.5
(6) Depending on the structural form and decisions made during design, particular structural members may be designed for the same, higher or lower consequences class than for the entire structure.
NOTE At the present time the requirements for reliability are related to the structural members of the construction works.
B.4. Reliability classes
(7) The reliability classes (RC) may be defined by the β reliability index concept.
(8) Three reliability classes RC1, RC2 and RC3 may be associated with the three consequences classes CC1, CC2 and CC3.
(9) Table B.2 gives recommended target values for the reliability index associated with reliability classes (see also annex C).
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Table B.2 Recommended target values for reliability index β (ultimate limit states)
Target values for β Reliability Class
1 year reference period 50 years reference period
RC3 5,2 4,3
RC2 4,7 3,8
RC1 4,2 3,3
NOTE A design using EN 1990 with the partial safety factors given in annex A1 and EN 1991 to EN 1999 is generally considered to lead to a structure with a β value greater than 3,8 for a 50 year reference period. Reliability classes for members of the structure above RC3 are not considered further in this annex, since these structures each require individual consideration.
B.5. Reliability differentiation by measures relating to the partial safety factors
(10) One way of achieving reliability differentiation is by distinguishing classes of γF factors to be used in fundamental combinations for persistent design situations. If the partial safety factors were calibrated as the reliability class 2 for a design life of 50 years, a multiplication factor KFI, see Table B.3, may be applied to the partial safety factors of the persistent design situation.
Table B.3 KFI factor for actions
Reliability class KFI factor for actions RC1 RC2 RC3
KFI 0,9 1,0 1,1
NOTE In particular, for class RC3, other measures as described in this annex are normally preferred to the use of KFI factors, whichI should be applied to unfavourable actions only.
(11) Alternatively, reliability differentiation may be applied using the partial safety factors for resistance γM. However, this approach is not normally used. An exception is in relation to fatigue verification (see EN 1993).
B.6. Complexity of structures
(12) The probability of failure due to essentially human errors depends on the complexity of the structure and requires differentiation for checking of design and execution.
(13) Three structural classes (SC) are given in Table B.4
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Table B.4 Structural classes (SC) depending on the complexity
SC Characteristic Examples
SC 1 Building works with structures of very low or low level of difficulty Simple statically determinate structures in costumory building technique made of timber , steel, masonry or unreinforced concrete or reinforced concrete structures without prestressed and composite structruers designed to withstand mainly predominantly static loads and without verification of lateral stability of the structure
a) Simple masonry buildings with down to foundation continuous passing load bearing walls without verification of lateral stability by calculation.
b) Lintels made by steel or reinforced concrete c) Steel and timber beams d) Simple floor structures that can be dimensioned by use of common
tables (tabulated formulas, precalculated dimensions etc.)
e) Simple roof trusses and roof girders f) Collar beam roofs g) Simple spread foundations
h) Gravity retaining walls and L-shaped retaining walls without back anchoring until a hight of 4 m
i) Simple scaffolds
SC 2
Building works with structures of averagely level of difficulty Difficult statically determinate or statically indeterminate plain structures in common types of construction without prestressed constructions and without difficult stability verifications.
a) Difficult statically determinate or statically indeterminate roof and slab structures in conventional types of construction
b) Timber structures with average effective span including glued timber beams
c) Simple composite structures without consideration of concrete creep and shrinkage
d) Structures for holding of load bearing and stiffening walls and slabs e) Braced skeleton structures, if single members can be verified by
use of simple formulae or tabules
f) Single- or two way spanning, multi-bay floor slabs under mainly static loads if not included in SC 1
g) Two-hinged frames without complex stability analysis h) Regular one story halls with required verification of lateral stability
i) Shallow foundations j) Retaining walls with a hight > 4 m and retaining walls without rear
anchoring under difficult soil or load conditions k) Simple anchored retaining walls
l) Plain pile foundation grillage m) Chimneys which don’t require verification against vibrations n) Cable styed masts if cable deflection can be neglected for
verification of averal stability
o) Simple tanks p) Simple vaults q) Conventional scaffolds
r) Multiple statically indeterminate structures as three-dimensional
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SC Characteristic Examples latticed framework or large-span roofing
s) Roof structures with conventional dimensions if treated as space frame structures
t) Long-span load bearing timber and glued timber hall structures
u) Structures where second order calculations are required to determine inner forces, including multi-storey buildings if deformation needs to be considered to determine adequate inner forces. For instance multi-storey frame load bearing structures, multi-storey load bearing skeleton with vertical posts and horizontal members,,boiler frame structures
v) Structures for which a structural analysis under consideration of nonlinear material behaviour is necessary
w) Structures which only could be verified with scaled model anylsis
x) Tower like structures where stability proof verification requires special design methods
y) Girder grillage structures and orthotropic plates z) Halls and hall like structures with crane-ways
aa) Structures designed based on ultimate load design method. bb) Folded structures and shells cc) Prestressed and posttensioned structures including prestressed
precast members
SC 3
Building works with structures of above-average level or very high level of difficulty Complex statically indeterminate structures and structural difficult load bearing systems in common construction types or structures with non-trivial load scenarios and action effects. Statically and structural uncommon highly complex systems with e.g. non-linear calculations or dynamic effects as well as complex structures in novel techniques and design assisted by testing
a) Multiple statically indeterminate structures as three-dimensional latticed framework or large-span roofing
b) Roof structures with conventional dimensions if treated as space frame structures
c) Long-span loadbearing timber and glued timber hall structures d) Structures where second-order calculations are required to
determine internal forces, including multi-storey buildings if deformation needs to be considered to determine adequate internal forces,e.g. multi-storey loadbearing frame structures, multi-storey load bearing skeleton with vertical posts and horizontal members,boiler frame structures
e) Structures for which a structural analysis under consideration of nonlinear material behaviour is necessary
f) Structures which only could be verified with scaled model anylsis g) Tower-like structures where proof of stability requires special
design methods h) Grillage structures and orthotropic plates
i) Sheds and shed-like structures with craneways j) Structures designed based on the ultimate load design method. k) Folded structures and shells
l) Prestressed and posttensioned structures including prestressed precast members
m) Composite structures if creep and shrinkage needs to be considered, prestressed composite structures and such one which only can be verified according to plasticity theory
n) Steel, reinforced concrete, prestressed and composite structures to be designed to provide a certain fire resistance class without the use of further fire protection systems
o) Curved beams p) Complex vaults and vault systems q) Complex retaining walls with multiple anchors
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SC Characteristic Examples r) Structures made by performance-tested masonry with special
requirements s) Stability verification for masts, chimneys and machine fundations
that need to be designed based on regular or simplified vibration analyses
t) Highrise buildings or with them comparable structures requirering a stability proof according to theory of second order and also a dynamic analysis
u) Complex statically indeterminate shallow foundations, complex pile foundations, special foundation systems and undercutting
v) Cable-braced masts and other buildings if cable deflection needs to be considered for stability verification of the structure
w) Cable braced fabric buildings and air halls if stability proof is required based on membrane theory
x) Cableway type of structures y) Complex containers, vessels, tanks and silos z) Structures where the yielding of connecting devices needs to be
considered to determine internal forces e.g. mainly dynamic loaded structures
aa) Complex scaffolds e.g. long spanning or very high scaffolds
(14) The classification should take account of the construction technology, i.e. where the risk of errors is high due to new or unconventional techniques, difficult conditions, etc.
B.7. Design
(15) In relation to 2.1 (7), the designer should have the appropriate qualifications and experience to perform the design and verification according to the specific project. Where the necessary design experience is not given, external experts should be involved.
NOTE Special requirements regarding the qualifications and experience of the designer can be determined on a national level. The type of structure, the materials used and the structural forms can affect these requirments.
(16) The complexity of a structure may require organisational and internal control measures for the specific project.
NOTE: EN ISO 9001:2000 is an acceptable basis for checking management measures where relevant. It must however, be supplemented by requirements relevant to the design in question. It is not a substitute for an independent check according to 2.1 (9).
B.8. Design check
(17) The design check level may be chosen with respect to the consequences class and the complexity of the structure, see B.12.
(18) Three design check levels (DCL) are shown inTable B.5.
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Table B.5 Design checklevels (DCL)
Design Check Level
Characteristics
Minimum recommended requirements for checking of calculations, drawings and specifications
DCL3
Independent external systematic checking
Third-party checking : checking performed by a national authority.
DCL2
Independent external systematic checking
Checking by an authorised independent external expert/licensed checking engineer or an organisation with equivalent checking qualification.
DCL1
Internal checking Checking within the organisation that prepared the design but by persons other than those originally responsible for the design and in accordance with the procedures of the organisation.
NOTE: Details and exceptions can be determined on a national level.
B.9. Execution
(19) The contractor shall have the appropriate qualifications as laid down in the relevant execution standards (i.e. EN 1090, EN 13670). Where the necessary experience is not given, competent external contractors shall be involved.
NOTE Special requirements regarding the qualifications, experience and equipment of the contractor should be determined on a national level. The type of structure, the materials used and the structural forms can affect these requirments.
(20) The complexity of a structure may require organisational and internal control measures for the specific project.
(21) Further guidance is available in relevant execution standards referenced in EN 1992 to EN 1996 and EN 1999.
B.10. Inspection during execution and design life
(22) Three inspection levels (IL) as shown in Table B.6 are linked to the consequences/reliability class selected and to the complexity of the structure, see B.12. Further guidance is available in relevant execution standards referenced in EN 1992 to EN 1996 and EN 1999.
Table B.6 Inspection levels (IL)
Inspection Level Characteristics Requirements
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IL3
Independent external systematic inspection in accordance with the procedures of a national authority.
Inspection performed by a national authority.
IL2
Independent external systematic inspection in accordance with the procedures of a national authority.
Inspection performed by an authorised external expert/licensed checking engineer or an organisation with equivalent checking qualification.
IL1
Internal inspection Inspection by the contractor based on relevant execution standards but by persons other than those originally responsible for the works.
NOTE 1. Inspection levels define the subjects to be covered by inspections of products and execution of works including the scope of inspection. The rules will thus vary from one structural material to another, and are to be given in the relevant execution standards.
NOTE 2: Details and exceptions can be determined on a national level.
B.11. Relations between different classes
B.11.1 Relation between CC and RC
(23) The three reliability classes RC1, RC2 and RC3 are related to the three consequences classes CC1, CC2 and CC3 as given in Table B.7.
Table B.7 Relation between CC and RC
Consequences Class
Corresponding Reliability Class
CC3 RC3
CC2 RC2
CC1 RC1
(24) A higher RC than that given in Table B.7 can be agreed between the partners involved in the project.
B.11.2 Determination of DCL and IL
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(25) In accordance with the reliability class taking into account the structural complexity expressed by the structural class, the design checking level and the inspection level for execution is defined in Table B.8.
Table B.8 Determination of DCL and IL (SC reduced to three classes)
Reliability Class
Structural Class Corresponding Design Check Class
Corresponding Inspection Level for execution
RC 3 SC 3 DCL 3 IL 3
RC 2 SC 2 DCL 2 IL 2
RC 1 SC 1 DCL 1 IL 1
(26) If required for other reasons, a higher DCL and/or IL than that given in Table B.8 can be agreed between the partners involved in the project.
B.12. Recommendations for application
B.12.1 New construction works
(27) Consequences Classes (CC) should be determined considering the following aspects:
− loss of human life, and
− economic,
− social or
− environemental consequences.
(28) The corresponding RC should be chosen with respect to the CC in accordance with Table B.7.
(29) The SC follows from the complexity of the structure according to Table B.4.
(30) The determination of DCL and IL should be in accordance with the RC and SC. A higher SC can require a higher DCL and IL than that resulting from the RC.
(31) The routines for checking design should place emphasis on those parts of the structure where a failure has major consequences with respect to the structural resistance, durability and function. Those routines include:
− Calculations and drawings
− Consistency between calculations, drawings and the execution specification
− Critical components (members, nodes, joints, supports and cross-section)
− Loads, models for calculating loads and design situations
− Structural analysis, models used and design parameters
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− Adequate knowledge of soil conditions and parameters
− Independent models and alternative calculations to check the design.
(32) The methods for inspecting of the execution should place emphasis on those parts of the structure where a failure would have the major consequences with respect to the structural resistance, durability and serviceability. Those methods include:
− Execution according to the specifications and drawings as well as the calculations and the execution parts of the corresponding ECs and additional execution regulations
− Personnel having the skills and training required for the work
− Inspections being properly documented
− Materials and construction products as specified and fit for their intended purposes.
NOTE: Additional guidance may be given in the various execution standards, eg. EN 13670 and EN 1090.
(33) Personnel performing internal systematic control measures should have the skills needed to assess the work performed and should have the same or a higher level of competence than that required to perform the work.
(34) In the case of external and independent checking, the person performing checking measures shall have an adequate level of competence and experience.
NOTE 1: The necessary competence and experience should be established by specific certificates or licences.
NOTE 2: Specific regulations and exceptions can be regulated in the National Annex.
B.12.2 Existing construction works
(35) A recurring inspection of the structural stability and the conditions of materials and structural members should be performed after a specified period of years, depending on the CC of the structure, in the case of visible damage and in the case of buildings or structures of high importance, see Table B.9..
Table B.9 Recurring inspections of structures with respect to CC
Consequences Class
Recurring inspections
CC3 Periodically, every n years at least
CC2 Periodically, and in the case of damage and defects relavant to safety
CC1 In the case of damage and defects relavant to safety
NOTE: Specific provisions and time intervals can be found in the National Annex.
(36) The recurring inspection for buildings with CC3 should take account of the following aspects:
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− Changes in the utilisation and the actions
− Structural changes influencing the stability and resistance
− Climatic conditions different from those assumed in the design phase
− Draining of rainwater and melt water as well as sealing against against water penetrattion and groundwater
− Safety barriers etc.
NOTE: Further guidance will be given in EN 1992 to EN 1999 as well as in the JRC report on existing structures.
(37) In the in case of CC2, periodic inspection is necessary but is the responsibility of the owner.
(38) Inspection in the case of CC 1 and 2 should place emphasis on those parts of the structure where damage and defects arose. It should focus on the clarification of the causes and the necessary rectification and repairs.
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