N 1069 -...

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

mailto:[email protected]

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

mailto:[email protected]

http://cen.iso.org/livelink/livelink/open/centc250wg7

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

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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

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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.

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- 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.

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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.

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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.

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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).

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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

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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

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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.”

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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.

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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..

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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.

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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


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.






(This chapter should be revised when the content

of the revised EN 1990 is known)

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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


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

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2010


Clause


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.

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2010


Clause


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


normative clauses in the new EN 1990 it may

be necessary to add some new term and

definitions.

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2010


Clause


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


normative clauses in the new EN 1990 it may

be necessary to add some new symbols.

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Section 2 Requirements




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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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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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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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;


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.

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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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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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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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




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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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




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.




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




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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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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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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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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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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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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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



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

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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




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.



analysis.

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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.



analysis.

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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.



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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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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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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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.


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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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(4)P No change



6.4.3.2 Combinations of actions for persistent or transient design situations (fundamental combinations)





6.4.3.3 Combinations of actions for accidental design situations


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6.4.3.4 Combinations of actions for seismic design situations



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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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




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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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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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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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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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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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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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-

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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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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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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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A1.4.4(3) No change

A1.4.4(4) No change

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Annex B




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 allow 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


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


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.




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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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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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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(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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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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(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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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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− 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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− 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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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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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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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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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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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



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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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.


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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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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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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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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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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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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Page 119

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



(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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