N 1069 CEN-TC250-WG7 N0001 EG EN1990

Transcription

1 CEN/TC 250 CEN/TC Structural Eurocodes of secretary: [email protected] Secretariat: BSI (United Kingdom) N 1069 CEN-TC250-WG7 N0001 EG EN Recommendations for amendments to EN 1990 "4-columnversion". Document type: Date of document: Other committee document Expected action: INFO Background: Committee URL:

2 CEN/TC 250/WG 7 N 1 CEN/TC 250/WG 7 CEN/TC 250/WG 7 - EN 1990 Basis of structural design of secretary: [email protected] Secretariat: SN (Norway) EG EN Recommendations for amendments to EN Document type: Other committee document Date of document: Expected action: INFO Background: Committee URL:

3 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 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 Notwithstanding the above considerations, WG7 (London, ) 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

4 Table of contents Introduction... 3 FOREWORD... 5 Section 1 General Section 2 Requirements Section 3 Principles of limit states design Section 4 Basic Variables Section 5 Structural analysis and design assisted by testing Section 6 Verification by the partial factor method Annex A1 (normative) Application for Buildings Annex B Annex C Appendix 1 PROPOSAL FOR THE MINIMUM CONTENTS OF THE STRUCTURAL DESIGN REPORT Appendix 2 PROPOSAL FOR THE ULS VERIFICATIONS FORMAT STR/EQU/GEO Appendix 3 BACKGROUND CALCULATIONS EQU/STR Appendix 4 PROPOSAL FOR THE AMENDMENT OF TABLE A1.2(B) Appendix 5 - ALTERNATIVE PROPOSAL BY WOLFRAM JÄGER FOR ANNEX B

5 Introduction The EG was set up by TC250 through its resolution n at the meeting in Limassol (Cyprus) in October 2007, and met for the first time in Brussels on 2 nd of July Eight subsequent meetings were held until February 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: 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 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 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 The resolution was agreed by unanimity. 3

6 - 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. 4

7 FOREWORD Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 This document supersedes ENV :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, 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: A1:2005 and including corrigenda dated December 2008 and April 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. Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal,Spain, Sweden, Switzerland and the United Kingdom. 5

8 Clause Foreword to amendment A1 EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 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 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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation No need for this part of the foreword in the new version. 6

9 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation Background of the Eurocode programme In 1975, the Commission of the European Community decided on an action programme in the field of construction, based on article 95 of the Treaty. The objective of the programme was the elimination of technical obstacles to trade and the harmonisation of technical specifications. Within this action programme, the Commission took the initiative to establish a set of harmonised technical rules for the design of construction works which, in a first stage, would serve as an alternative to national provisions the in force in the Member States and, ultimately, would replace them. For fifteen years, the Commission, with the help of a Steering Committee with Representatives of Member States, conducted the development of the Eurocodes programme, which led to the first generation of European codes in the 1980 s. In 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. 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. 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 1989, the Commission and the Member States of the EU and EFTA decided, on the basis of an agreement 2 between the Commission and CEN, to transfer the preparation and the publication of 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). 7

10 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 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 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 8

11 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 9

12 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. 10

13 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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. recommendation Minor editorial changes only here. 11

14 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Links between Eurocodes and harmonised technical specifications (ENs and ETAs) for products Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 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 1 st 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.. 12

15 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. 13

16 Clause National annex for EN 1990 EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 This standard gives alternative procedures, values and recommendations for classes with notes indicating where national choices may have to be made. Therefore the National Standard implementing EN 1990 should have a National annex containing all Nationally Determined Parameters to be used for the design of buildings and civil engineering works to be constructed in the relevant country. National choice is allowed in EN 1990 A1 through National choice is allowed in EN 1990 A2 through Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause This standard gives alternative procedures, recommendations for values and classes with notes indicating where national choices may have to be made. Therefore the National Standard implementing EN 1990 should have a National Annex containing all Nationally Determined Parameters to be used for the design of buildings and civil engineering works to be constructed in the relevant country. National choice is allowed in EN 1990 A1 through National choice is allowed in EN 1990 A2 through recommendation National choice is allowed in EN 1990 A3 through National choice is allowed in EN 1990 A4 through National choice is allowed in EN 1990 A5 through (This chapter should be revised when the content of the revised EN 1990 is known) 14

17 Section 1 General Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 1.1 Scope 1.1 (1) No change 1.1 (2) No change 1.1 (3) No change 1.1 (4) No change 1.2 Normative references Assumptions 1.3 (1) 1.3 (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 No change No change 15

18 Clause New 1.3 (3) EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (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. recommendation 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. 16

19 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April Distinction between Principles and Application Rules 1.4 (1) 1.4 (2) 1.4 (3) 1.4 (4) 1.4 (5) 1.4 (6) 1.5 Terms and definitions Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause No change No change No change No change No change No change 1.5 No change except for Clause see below). Additionally if new Eurocode standards (e.g. glass, frp etc are cited in normative clauses in the new EN 1990 it may be necessary to add some new term and definitions. recommendation 17

20 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 characteristic value of an action (F k ) 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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause characteristic value of an action (F k ) 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. recommendation The deleted part was causing confusion to practitioners. 1.6 Symbols 1.6 No change. Additionally if new Eurocode standards (e.g. glass, frp etc are cited in normative clauses in the new EN 1990 it may be necessary to add some new symbols. 18

21 Section 2 Requirements Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April Basic requirements 2.1 (1)P Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause No change recommendation 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 19

22 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April (4)P 2.1 (5)P Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause No change No change recommendation 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. 20

23 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April Reliability Management 2.2 (1)P Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause No change recommendation 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. 2.2 (3) No change 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 (4) No change 21

24 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 (5) The levels of reliability relating to structural 2.2 (5) 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 g) adequate inspection and maintenance according to procedures specified in the project documentation. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (5) The levels of reliability relating to structural resistance and serviceability can be achieved by suitable combinations of: a) preventative and protective measures (e.g. implementation of safety barriers, active and passive protective measures against fire, protection against risks of corrosion such as painting or cathodic protection); b) measures relating to design calculations: representative values of actions; the choice of partial factors; NOTE See also Annex B c) measures relating to quality management; NOTE See also Annex B d) measures aimed to reduce errors in design and execution of the structure, and gross human errors; NOTE See also Annex B e) other measures relating to the following other design matters: the basic requirements; the degree of robustness (structural integrity); durability, including the choice of the design working life; the extent and quality of preliminary investigations of soils and possible environmental influences; the accuracy of the mechanical models used; the detailing; f) efficient execution, e.g. in accordance with execution standards referred to in EN 1991 to EN g) adequate inspection and maintenance according to procedures specified in the project documentation. recommendation 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 22

25 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 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 Indicative design working life Indicative Examples design working life (years) Design working life category 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 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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (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 Indicative design working life Indicative Examples design working life (years) Design working life category 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 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. recommendation 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.) 23

26 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (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. recommendation The background for this minor amendment is to clarify that durability of structures are however a designed property and not a tested property. 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. 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) 2.4 (3)P 2.4 (4) No change No change No change 24

27 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (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. recommendation 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. 25

28 Section 3 Principles of limit states design Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 3.1 General 3.1(1)P No change 3.1(2) No change 3.1(3) No change 3.1(4) No change 3.1(5) Verification of limit states that are concerned with time dependent effects (e.g. fatigue) should be related to the design working life of the construction. 3.2 Design Situations 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(1)P No change 3.2(2)P No change 26

29 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April (3)P No change 3.3 Ultimate Limit States 3.3(1)P No change 3.3(2) No change 3.3(3) No change Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation recommendation 3.3(4)P No change An Appendix includes the proposal for a re-arrangement of the ULS list, consistently with changes proposed in Section 6 and Annex A1. Clause 3.4 Serviceability Limit States EN 1990: A1:2004 incorporating corrigenda December 2008 and April (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 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 27

30 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 28

31 Section 4 Basic Variables Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April Actions and environmental influences Classification of actions Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 Characteristic values of actions 4.1.2(1)P No change 4.1.2(2)P No change 29

32 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April (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. G k should then be taken equal to the mean value. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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. G k should then be taken equal to the mean value. recommendation NOTE This coefficient of variation can be in the range of 0,05 to 0,10 depending on the type of structure. 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 G k,inf and G k,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 NOTE For the settlement of foundations, see EN 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 NOTE For the settlement of foundations, see EN Align the rules with the previous treatment of variability of G (6) No change 4.1.2(7)P No change 4.1.2(8) No change 30

33 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April (9) No change 4.1.2(10) No change Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 New clause, to implement rules specific to non linear analysis Other representative values of variable actions 4.1.3(1)P No change Representation of fatigue actions 4.1.4(1) No change 31

34 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April (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 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 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.) recommendation 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. 32

35 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 Representation of dynamic actions recommendation New Clause, to clarify the significance of the load values in fatigue load models 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. (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. To make the clause more precise Geotechnical actions NOTE Limits of use of these models are described in the various Parts of EN NOTE Limits of use of these models are described in the various Parts of EN (1)P No change 33

36 Clause Environmental influences EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 34

37 Clause 4.3 Geometrical data EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 35

38 Section 5 Structural analysis and design assisted by testing Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April Structural analysis Structural modelling Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (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 recommendation. New clause to provide more information for non-linear analyses, especially when applying non linear Finite Element analyses 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 In this case a note in the foreword should clarify that further specific provisions are given in EN 1991 to EN 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 36

39 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 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 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 recommendation. vibrations. To be agreed the elimination of all such references (see comment to 5.1.2) 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 37

40 Section 6 Verification by the partial factor method Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 6.1 General 6.1(1)P No change 6.1(2) No change 6.1(3) No change 6.1(4) No change 6.1(5)P No change 6.1(6) Where first or second order non-linear finite element analyses are used in analyses to simulate both load effects and ultimate resistance the concept of a global factor covering both uncertainties on the action side and the material side may be used as an alternative to the use of design values directly. The global factor shall take due account of the behaviour of the various materials involved in the failure modes investigated, as well as differences in the material factors. Details for the various construction materials are given in EN 1992 to EN NOTE: the rules according to 6.4.3(4) should be taken into account. New clause, to implement rules specific to non linear analysis. 38

41 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 γ RRd. 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. recommendation New clause, to implement rules specific to non linear analysis. 39

42 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 Limitations 6.2(1) No change 6.3 Design values Design values of actions 6.3.1(1) No change 6.3.1(2) No change 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. recommendation New clause, to implement rules specific to non linear analysis. 40

43 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April Design values of the effects of actions Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 Design values of materials or product properties 6.3.3(1) No change 6.3.3(2) No change 41

44 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April Design values of geometrical data Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 6.3.4(1) No change 6.3.4(2)P No change 6.3.4(3) No change 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 General 42

45 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 6.4.1(1)P d) FAT : Fatigue failure of the structure or structural members. d) FAT : Fatigue failure of the structure or structural members. Editorial NOTE For fatigue design, the combinations of actions are given in EN 1992 to EN 1995, EN 1998 and EN NOTE For fatigue design, the combinations of actions, where relevant, are given in EN 1991 to EN (2)P No change 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 43

46 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April Combination of actions (fatigue verifications excluded) General Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation (1)P No change (2) No change (3) No change (4)P No change (5) No change (6) No change Combinations of actions for persistent or transient design situations (fundamental combinations) (1) No change (2) No change (3) No change (4) No change Combinations of actions for accidental design situations (1) No change 44

47 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April (2) No change (3) No change (4) No change Combinations of actions for seismic design situations (1) No change (2) No change Partial factors for actions and combination of actions 6.4.4(1) No change Partial factors for materials and products 6.4.5(1) No change 6.5 Serviceability limit states Verifications 6.5.1(1)P No change Criteria 6.5.2(1) No change Combination of actions Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 45

48 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April (1) No change 6.5.3(2) No change 6.5.3(3) No change 6.5.3(4)P No change Partial factors for materials 6.5.4(1) No change Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 46

49 Annex A1 (normative) Application for Buildings Clause A1.1 Field of application EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 47

50 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 A1.2.1(4) No change Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 , specify Ψ values for ice and water actions A1.3 Ultimate limit states 48

51 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 A1.3.1 Design values of actions in persistent and transient design situations Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 49

52 Clause Table A1.2(A) EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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. 50

53 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 A1.3.2 Design values of actions in the accidental and seismic design situations Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 51

54 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation A1.4.2(3)P The serviceability criteria for deformations and vibrations shall be defined : The serviceability criteria for deformations and vibrations shall be defined : depending on the intended use ; depending on the intended use ; in relation to the serviceability requirements in accordance with 3.4 ; in relation to the serviceability requirements in accordance with 3.4 ; independently of the materials used for supporting structural member. 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 52

55 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation A1.4.3(2) Vertical deflections are represented schematically in Figure. A1.1. Vertical deflections are represented schematically in Figure. A1.1. See also National Annexes : Belgium : NA to EN 1990 Figure A1.1 - Definitions of vertical deflections Figure A1.1 - Definitions of vertical deflections Finland : NA to EN , EN & EN Key : w c Precamber in the unloaded structural member w 1 Initial part of the deflection under permanent loads of the relevant combination of actions according to expressions (6.14a) to (6.16b) w 2 Long-term part of the deflection under permanent loads w 3 Additional part of the deflection due to the variable actions of the relevant combination of actions according to expressions (6.14a) to (6.16b) w tot Total deflection as sum of w 1, w 2, w 3 w max Remaining total deflection taking into account the precamber The limiting design values of calculated vertical deflections depend on the serviceability requirements. NOTE Recommended limiting design values of static calculated vertical deflections w max are given in Table A1.6. Table A1.6 : Recommended limiting values of static calculated deflection w max as a function of L, the span or twice the length of a cantilever Serviceabili ty requiremen t Combinatio n of actions to be considered Structure in general Secondary structural elements Functioning of structure Characteristic, expressions (6.14a/b) Comfort of users Frequent, expression (6.15a/b) Appearance of structure Quasipermanent, expression (6.16a/b) L/400 L/300 L/250 L/200 53

56 Clause A1.4.3(3) EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 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 and EN 1992 to EN Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 and EN 1992 to EN 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. recommendation 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 54

57 Clause A1.4.3(7) EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Horizontal displacements are represented schematically in Figure A1.2. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause Horizontal displacements are represented schematically in Figure A1.2. recommendation Key : Figure A1.2 - Definition of horizontal displacements u Overall horizontal displacement over the building height H u i Horizontal displacement over a storey height H i. Figure A1.2 - Definition of horizontal displacements Key : u Overall horizontal displacement over the building height H u i Horizontal displacement over a storey height H i. Horizontal deflections should satisfy the requirements of functioning. 55

58 Clause A1.4.3(7) (continue) EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause NOTE Limiting design values of horizontal deflections are recommended in Table A1.7. recommendation Table A1.7 : Recommended limiting design values of horizontal deflections as a function of height H of building or storey height H i Serviceability requirement Combination of actions to be considered Functioning of structure Characteristic, expressions (6.14a/b) Single-storey H/400 buildings Multi-storey buildings: -in general H i /200 Comfort of users Frequent, expression (6.15a/b) Appearance of structure Quasipermanent, expression (6.16a/b) See also National Annexes : Belgium : NA to EN 1990 Finland : NA to EN , EN & EN with brittle partition walls H i /500 A1.4.4 Vibrations A1.4.4(1) No change 56

59 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. See also National Annexes : Belgium : NA to EN 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 7,0 Hz Concert halls without permanent seating Concert halls with 3,4 Hz permanent seating Values to be further discussed in detail. Table from the DK National Annex 57

60 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 A1.4.4(3) No change A1.4.4(4) No change Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 58

61 Annex B Clause B1 Scope and field of application EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 (1) This annex provides additional guidance to 2.2 (Reliability management) and to appropriate clauses in EN 1991 to EN 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 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (1) This annex provides additional guidance to 2.2 (Reliability management), 2.5 (Quality management) and to appropriate clauses in EN 1991 to EN 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 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 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. recommendation 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 59

62 (2) The approach given in this Annex recommends the following procedures for the management of structural reliability for construction works (with regard to ULSs, ex- cluding fatigue) : a) In relation to 2.2(5)b, classes are introduced and are based on the assumed consequences of failure and the exposure of the construction works to hazard. A procedure for allowing moderate differentiation in the partial factors for actions and resistances corresponding to the classes is given in B3. NOTE Reliability classification can be represented by indexes (see Annex C) which takes account of accepted or assumed statistical variability in action effects and resistances and model uncertainties. b) In relation to 2.2(5)c and 2.2(5)d, a procedure for allowing differentiation between various types of construction works in the requirements for quality levels of the design and execution process are given in B4 and B5. NOTE Those quality management and control measures in design, detailing and execution which are given in B4 and B5 aim to eliminate failures due to gross errors, and ensure the resistances assumed in the design. (3) The procedure has been formulated in such a way so as to produce a framework to al- low different reliability levels to be used, if desired. (3) The approach given in this Annex recommends the following procedures for the management of structural reliability for construction works: a) In relation to 2.2(5)b, classes are introduced and are based on the assumed consequences of failure and the exposure of the construction works to hazard. A procedure for allowing moderate differentiation in the partial factors for actions and resistances corresponding to the classes is given in B2. NOTE Reliability classification can be represented by differentiation of target levels of β indexes (see Annex C) which takes account of accepted or assumed statistical variability in action effects and resistances and model uncertainties. b) In relation to 2.2(5)c and 2.2(5)d, a procedure for allowing differentiation between various types of construction works in the requirements for quality levels of the design and execution process including control/verification are given in B3 and recommendations for a complete system is given in B4. NOTE Those quality management and control measures in design, detailing and execution which are given in B3.1 and B3.2 aim to eliminate failures due to gross errors, and avoid errors in design and execution and thereby ensure a structure with the intended performance. (4) The procedure in this Annex has been formulated in such a way so as to produce a framework for EN 1990 and EN 1992 to EN 1999 and the relevant product and execution standards to allow differentiation of reliability all structures or structural elements designed to comply with the Eurocodes, see (2). In table B1 it is assumed a one-toone 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. 60

63 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. Delete. Symbols are not needed KFI Factor applicable to actions for reliability differentiation β Reliability index 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. 61

64 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 (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 At the present time the requirements for reliability are related to the structural members of the construction works. (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. 62

65 B3.2 Differentiati on by β 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. B2.2 Differentiation by β 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. 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. (3) Table B2 gives recommended minimum values for the reliability index associated with reliability classes (see also annex C). (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. 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 β (ultimate limit states) Table B3- Recommended target values for reliability index β 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 63

66 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 γ F 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 K FI, 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 γ F 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 K FI, see Table B4, may be applied to the 64

67 partial factors. Table B3 - K FI factor for actions NOTE In particular, for class RC3, other measures as described in this Annex are normally preferred to using K FI factors. K FI should be applied only to unfavourable actions. (2) Reliability differentiation may also be applied through the partial factors on resistance γ M. 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 γ F. 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 Table B4 Recommended K FI factor for actions NOTE Other measures as described in this Annex in Clauses B3 and B4 are normally preferred to using K FI factors to achieve increased reliability, as it means less use of construction materials. (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 γ F. However, this is not normally used. 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. k FI <1,0 rather than more lenient quality management. 65

68 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 Text is moved (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 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. 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 66

69 (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. 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. 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. 67

70 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 Table B5- Design quality levels (DQL) The design quality levels in table B5 are intended for the pro-active part (Quality Assurance) directed towards ensuring that design will be done correctly by proper organization, plans, procedures and qualifications etc. 68

71 (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 69

72 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 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. 70

73 Further guidance is available in relevant execution standards referenced by EN 1992 to EN NOTE EN and EN 1090 apply Execution classes and gives requirements relevant for the execution and inspection related to these classes. (3) For construction products that are manufactured off site to a harmonised European specification, the differentiation in terms of execution quality management should take into account the conformity assessment requirements given in the relevant European specification. NOTE Conformity assessment requirements may require certification of the manufacturer s system for factory production control (FPC) by a competent certification body. In terms of Table B8 this is above IL2 but below IL3 as it is external inspection of the manufacturer s process but not external inspection of specific products. However, according to B1(2) it can be acceptable that the external inspection of the specific product is covered by specific procedures within the manufacturer s system for FPC if permitted by the National Annex, and a full IL3 is not required. Table B7 Execution classes (EXC) The execution classes in table B7 are intended for the pro-active part (Quality Assurance) directed towards ensuring that execution will be done correctly by proper organization, plans, procedures and qualifications etc. It is possible that execution standards may use the execution 71

74 class as the prime mechanism to regulate both the proactive part and the reactive part (inspection levels), this is the case in EN 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 72

75 D. NOTE Rules for various materials may be given or referenced in EN 1992 to EN 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 73

76 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 oneto-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 74

77 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 75

78 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) 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. - loads, models for calculation of loads and design situations - structural models and calculation of load effects 76

79 - 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 77

80 - 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 and EN 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. 78

81 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 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 INDEPENDENT DSL3 / IL3 INTERNAL SYSTEMATIC DSL2 / IL2 Interface between project and building authorities Documentation Audit SELF CHECKING DSL1 IL1 Quality in a project should come from below, as good quality work from the very start. Not as corrections from above. 79

82 Annex C Note: The original text of Annex C given in the 3 rd column is in blue colour, original text of Section 6 is in green colour. Clause C1 Scope and field of applications EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 (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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation. Further guidance may be found in ISO 2394, JCSS Probabilistic Model Code and JCSS Risk Assessment in Engineering - Principles, System Representation & Risk Criteria. 80

83 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation. NOTE: The majority of structures can be designed according to the suite of Eurocodes EN 1990 to EN1999 without any need for the application of the material presented in this annex. Application may however be considered useful for design situations that are not well covered and for possible extensions of the code. C2 Symbols Added new symbols: P ft target failure probability β t target reliability index Deleted: Prob(.) Probability C4 Overview of reliability methods C.5 Reliability index β (3) In both the Level II and Level III methods the measure of reliability should be identified with the survival probability P s = (1 - P f ), where P f 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 P 0 then the structure should be considered to be unsafe. (1) In the Level II procedures, an alternative measure of reliability is conventionally defined by the reliability index β which is related to P f by: P = Φ( β ) (C.1) f where Φ is the cumulative distribution function of the (3) In both the Level II and Level III methods the measure of reliability should be identified with the survival probability P s = (1 - P f ), where P f 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 P ft then the structure should be considered to be unsafe. C.5 Probability of failure and reliability index β 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 81

84 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 standardised Normal distribution. The relation between P f and β is given in Table C1. Table C1 - Relation between β and P f P f β 1,28 2,32 3,09 3,72 4,27 4,75 5,20 (2) The probability of failure P f 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: P f = Prob(g 0) (C.2a) If R is the resistance and E the effect of actions, the performance function g is : Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 timeinvariant 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 P f, 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 P f is related to the reliability index β by P = Φ( β ) (C.1) f recommendation. g = R E (C.2b) where Φ is the cumulative distribution function of the standardised Normal distribution. The relation between P f and β is given in Table C1. with R, E and g random variables. Table C1 - Relation between β and P f P f β 1,28 2,32 3,09 3,72 4,27 4,75 5,20 82

85 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 (3) If g is Normally distributed, β is taken as : Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (3) The probability of failure P f 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: recommendation. µ g β = (C.2c) σ g P f = P(g 0) (C.2a) where : µ g is the mean value of g, and (4) If R is the resistance and E the effect of actions, the limit state equation or performance function g is: σ g is its standard deviation, g = R E (C.2b) so that : with R and E statistically independent random µ βσ = 0 (C.2d) g g variables. 83

86 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 and P = Prob( g 0) = Prob( g βσ ) (C.2e) f µ g g Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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: β µ µ R E = (C.2c) 2 2 σ + σ R E recommendation. For other distributions of g, β is only a conventional measure of the reliability where: µ, µ are mean values of R and E R E σ, σ are standard deviations of R and E R 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). P s = (1 - P f ). NOTE: For calculation of the reliability index see ISO 2394 or Probabilistic Model Code of JCSS [xx]. C.5.3 Time-variant reliability problems 84

87 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation. (1) Two classes of time-dependent problems are considered, namely those associated with failures caused by extreme values, and failures caused by the accumulation of effects over time. (2) In the case of failure due to extreme values, a single action process may be replaced by a random variable representing the extreme characteristics (minimum or maximum) of the random process over a chosen reference period, typically the life time or one year. If there is more than one stochastic process involved, they should be combined, taking into account the dependencies between the processes. (3) An exact and general expression for the failure probability of a time varying process on a time interval (0,t) can be derived from integration of the conditional failure rate h(τ) according to: t Pf (0, t) = 1 exp h( τ ) dτ (C.3) 0 (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): 85

88 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause ( ( ( )) 0 ( ( ) 0) ( ) lim P g X t > ν t g X t + = (C.4) 0 (5) If failure at the start (t = 0) explicitly is considered: P(0,t) = P f (0) + [1 P f (0)] [1 exp ] (C.5) recommendation. in which P f (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. C.6 Target values of reliability index β (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 ; (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. (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. 86

89 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 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 [ Φ( β ] n Φ( β = (C.3) 1 ) ) n where β n is the reliability index for a reference period of n years, design situations, and for reference periods of 1 year and 50 years β 1 is the reliability index for one year. Table C2 - Target reliability index β for Class RC2 structural members 1) Limit state Target reliability index Ultimate 1 year 50 years Fatigue 4,7 3,8 Serviceability 1,5 to 3,8 (irreversible) 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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (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 n E defined as R( a) = i = 1 P i C i where n is the number of E possible events with P and C being the probability and i i 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 recommendation. 87

90 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 β for Class RC2 structural members 1) Limit state Target reliability index Ultimate 1 year 50 years Fatigue 4,7 3,8 Serviceability 2,9 to 4,7 1,5 to 3,8 (irreversible) 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 recommendation. 88

91 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 [ Φ( β ] n Φ( β = (C.6) 1 ) ) n where β n is the reliability index for a reference period of n years, β 1 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. recommendation. 89

92 Clause C7 Approach for calibration of design values EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 (S) failure boundary g = R E = 0 P design point Figure C2 - Design point and reliability index β 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 E d and resistances R d should be defined such that the probability of having a more unfavourable value is as follows: Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 β t 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 = w i (β i β t ) 2 (w i 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 β t should be based on optimisation procedure. Different values of reliability index β t 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. recommendation. Need for explanation of basis of calibration of reliability elements is based on requests of users. P(E > E d ) = Φ (+α E β) (C.6a) 90

93 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 P(R R d ) = Φ (-α R β) (C.6b ) where β n is the target reliability index (see C6) α E and α R, 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. α E and α R may be taken as - 0,7 and 0,8, respectively, provided 0,16 < σ E /σ R < 7,6 (C.7) where σ E and σ R are the standard deviations of the action effect and resistance, respectively, in expressions (C.6a) and (C.6b). This gives P(E > E d ) = Φ(-0,7β) P(R R d ) = Φ(-0,8β) (C.8a) (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 σ E and σ R 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 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 E d < R d (C.7) where the design values of action effect E d and resistance R d are given as E d = E{F d1,f d2, a d1, a d2,.. θ d1, θ d2, } R d = R{X d1,x d2, a d1, a d2,.. θ d1, θ d2, } (C.8a) (C.8b) recommendation. 91

94 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 P (E > E d ) = 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 µ αβσ Lognormal µ exp( αβv ) for V = σ/µ < 0,2 Gumbel 1 u - ln{- lnφ(-αβ )} a 0, 577 π where u = µ ; a = a σ 6 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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause where F d is the design value of action X d is the design value of resistance property a d is the design value of geometrical property θ d 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 E d and resistances R d should be defined such that the probability of having a more unfavourable value is as follows F E (e d ) = Φ(+α E β t ) F R (r d ) = Φ( α E β t ) (C.9a) (C.9b) where Φ is the cumulative distribution function of the standardised Normal distribution β t is the target reliability index with reference period T (see C6) α E and α R, 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 α E = -0,7 and α E = -0,28 for accompanying unfavourable actions may be taken and the coefficient of sensitivity for resistance α R = 0,8 provided that the ratio between standard deviations of the load effect σ E and resistance σ R is in a range recommendation. 92

95 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 0,16 <σ E /σ R < 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 α E = -0,28 the values defined by expression (C.9) correspond approximately to the 0,90 fractile. (5) The design value F d of the action and resistance R d may be expressed from (C.9) as recommendation. F d (β t ) = F -1 F [Φ( α E β t )] R d (β t ) = F -1 R [Φ(+α R β t )] (C.11a) (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 µ αβσ Lognormal µ exp( αβv ) for V = σ/µ < 0,2 Gumbel 1 u - ln{-lnφ (-αβ )} a 0, 577 π where u = µ ; a = a σ 6 93

96 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause Weibull c 1 c1 x c ln(φ 1 ( β )) u p sup 2 where x sup = µ + u p σ c1 + 1 c1 1 Γ( ) ln(φ ( β )) c1 = c c1 + 1 Γ( ) Γ ( ) c c 1 1 recommendation. 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 = b δ R( X, a) (C.12) where R( X, a) 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 V X. 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 V δ b is bias in resistance model (can be determined using 94

97 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause the method in the Annex D Design assisted by testing ). (2) The design value of the resistance R can be d determined by different models, see Cl (3) Model 1 where design values are determined for the material strength parameters recommendation. R( X, a ) d d R d = (C.13) γ where a d is the design value for geometrical data. X d 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) X is d determined by k X = d (C.14) η X γ m where η is the conversion factor taking into account load duration effects, moisture, temperature, scale effects, 95

98 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause etc. X k is the characteristic value of strength parameter generally defined by the 5% fractile γ is the partial factor for strength parameter depending m on the coefficient of variation V, see Table C4. X NOTE If the resistance model is linear in the strength parameters then R = R( X, a ) and X for each of the strength d d d d parameters is obtained using a partial factor γ = γ γ. (5) Model 2 where a characteristic resistance is obtained using characteristic values of the material strength parameters M m recommendation. R( η X, a ) k k R d = (C.15) γ M where γ M is the partial factor related to uncertainty of the strength parameters X through the resistance function R(X,a), V R. (6) Model 3 where a characteristic resistance is estimated based on tests R γ k R = d (C.16) M where R k is the characteristic resistance estimated based on tests, see the Annex D Design assisted by testing. R is k generally defined by the 5% fractile γ M is the partial factor related to uncertainty of the 96

99 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause resistance obtained based on tests, V. R (7) In model 1 the partial factor γ depends on the m uncertainty of the strength parameter(s) and γ depends on the uncertainty of the resistance model, incl. bias recommendation. γ δ γ = (C.17) b where γ δ is partial factor depending on the model uncertainty with coefficient of variation V, 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 R ( X, a). The material partial factors are correspondingly obtained from γ δγ γ = R (C.18) M b where γ R is partial factor depending on the resistance uncertainty with coefficient of variation V. Coefficient V R R depends on the uncertainties of the strength parameters though the resistance function R ( X,a ), see Table C4 γ is partial factor depending on the model uncertainty δ with coefficient of variation V. δ (9) In model 3 the partial factor γ depends on the M uncertainty of the test results including statistical uncertainty δ 97

100 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause γ = γ M R (C.19) where γ R is partial factor depending on the resistance uncertainty with coefficient of variationv R. Coefficient V R 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 γ, γ - partial safety factor for strength m R parameter or resistance. Coefficient of variation for strength parameter in model 1, 5 % 10 % 15 % 20 % 25 % V or resistance in X model 2 and 3, V R γ in model 1 or m in model 2 and 3 γ R recommendation. 98

101 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause Table C5 γ - partial safety factor for model uncertainty. δ Coefficient of 5 % 10 % 15 % 20 % 25 % variation for model uncertainty for resistance model in model 1, V γ δ δ 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 E d (exp. (6.2) in EN 1990) may be expressed as: d { γ F ; a } 1 E = γ E i (C.20) Sd f,i rep, i d where a d is the design value of the geometrical data γ Sd 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): { F ; a } 1 E = E γ i (C.21) d F,i rep,i d where γ = γ d γ (C.22) F,i S f,i NOTE Further guidance is given for non-linear structural analyses. recommendation. 99

102 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (3) The partial factor of action F is based on the ratio between the design value F d and the characteristic value F k of an action given as recommendation. γ F = F d /F k (C.23) C7.4.1 Partial factors of permanent actions (1) Characteristic value of a permanent action G k may be commonly considered as a mean value (see EN ) based on nominal values of geometry and mean densities, therefore G k = µ G. (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 G k,inf = µ G 1,64 σ G = µ G (1 1,64 V G ) G k,inf = µ G + 1,64 σ G = µ G (1 + 1,64 V G ) where V G is the coefficient of variation µ G is the mean σ G is the standard deviation. (3) The design value of the permanent action G d may be determined as G d = µ G α G β σ G = µ G (1 + 0,7β V G ) (C.24) 100

103 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (4) The partial factor for self-weight γ g is given as the ratio between the design and characteristic values γ g = G d / G k = µ G (1 α G β V G )/ µ G = 1 α G β V G (C.25) where V G is the coefficient of variation of permanent action. In common cases the coefficient of variation of selfweight 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 V G = 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 α G = 0,7 and the target value of reliability index β t = 3,8, the partial factor is determined as γ g = 1 α G β V G = 1 + 0,7 3,8 0,05 1,15 If the self-weight is a non-dominant action (α G = 0,28), see expression (6.10b), the partial factor can be determined as γ g = 1 + 0,28 3,8 0,05 = 1,05 It should be noted that the coefficient γ sd 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 γ sd = 1,1 is considered then the partial factor γ G for a leading permanent action is given as γ G = 1,15 1,1 1,27 and for an accompanying permanent action recommendation. 101

104 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause γ G = 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 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 Q p = µ Q {1 V Q [0,45 0,78lnN + 0,78 ln( lnp)]} (C.26) where V Q 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 recommendation. 102

105 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause Q k = µ Q {1 V Q [0,45 + 0,78 ln( ln0,98)]} (C.27) and the design value of action Q d = µ Q {1 V Q [0,45 0,78lnN + 0,78 ln( ln(φ -1 ( α E β))]} (C.28) where Φ is the standard Normal distribution function β is the reliability index corresponding to the reference period α E 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) γ q = 1 V Q (0, 45 0, 78lnN + 0, 78ln( ln(φ 1 V Q 1 (0, , 78ln( ln0, 98)) under the assumption of a Gumbel distribution. ( α β ))) E (C.29) 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 recommendation. 103

106 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 σ 6 m N( σ ) = 2 10 = K σ (C.30) σ C where σ is the characteristic fatigue strength defined as the C 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: recommendation. n γ Ff σ i i i 2 10 σ C / γ Mf m 6 1 (C.31) where γ Mf is the partial factor for fatigue strength γ Ff is the partial factor for fatigue load n i is the number of cycles with fatigue stress range σ i (4) For non-linear SN-curves the design value of the 104

107 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause Miner s sum should fulfil: recommendation. i N i ( γ γ σ ) Mf n Ff i 1 (C.32) (5) The partial factor for fatigue strength γ is obtained Mf from: γ = λ γ (C.33) Mf Mf M 0 f where γ M0f λ Mf is the partial factor for fatigue strength depending on uncertainties related to the SN-curve and the Miner s rule is the factor accounting for bias and other fatigue strength uncertainties not included in γ scales and temperature effects. M 0 f, such as (6) The partial factor for fatigue load γ is obtained from: Ff γ = λ γ (C.34) Ff Ff F 0 f where γ M0f λ Mf is the partial factor for fatigue stress depending on uncertainties related to fatigue load and stress assessment is the factor accounting for bias and other fatigue stress uncertainties not included in different load spectra. γ such as (7) The partial factors γ and γ in Tables C5 and C6 M 0 f F 0 f are calibrated such that failure probabilities for the relevant F 0 f 105

108 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause failure modes are close to the target reliability level in Table C2. The partial factor coefficient of variations l K γ M 0 f depends on the V og for the fatigue strength parameter, logk and V for the Miner s sum. The partial factor γ depends on the coefficient of variation, V for F 0 f Ff 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 V logk 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. γ - partial factor for fatigue strength. M 0 f Coefficient of variation, V logk for fatigue strength parameter, logk 10 % 20 % 30 % γ for V = 0 % M 0 f γ for V = 30 % M 0 f recommendation. 106

109 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause Table C7. γ - partial factor for fatigue stress. F 0 f Coefficient of 5 % 10 % 15 % 20 % 25 % 30 % variation, V for fatigue Ff stress γ F 0 f recommendation. C9 Partial factors in EN 1990 Uncertainty in representative values of Model uncertainty in actions and action γ f γ Sd γ F Model uncertainty in resistance, bias in resistance model (see Annex D) γ Rd Uncertainty in basic variables describing resistance γ m γ M C10 0 factors Expression for general distribution in Table C4 for ψ o for the case of two variable actions 1 N1 F { Φ( 0, 4β' ) } s 1 N F Φ( 0, 7β ) 1 s { } Figure C3 Relation between individual partial factors Expression in Table C8 for ψ o for the case of two variable actions 1 N1 F { Φ( 0, 4β' ) } s 1 N F Φ( 0, 7β' ) 1 s { } 107

110 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; 108

111 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. 109

112 Appendix 2 PROPOSAL FOR THE ULS VERIFICATIONS FORMAT STR/EQU/GEO (more appropriate for structures below ground) Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 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 Failure due to excessive deformation is structural failure due to mechanical instability. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 Failure due to excessive deformation is structural failure due to mechanical instability. recommendation 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

113 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April General Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 6.4.1(1)P The following ultimate limit states shall be verified as relevant : a) EQU : Loss of static equilibrium of the structure or any part of it considered as a rigid body, where : minor variations in the value or the spatial distribution of permanent actions from a single source are significant, and the strengths of construction materials or ground are generally not governing ; b) STR : Internal failure or excessive deformation of the structure or structural members, including footings, piles, basement walls, etc., where the strength of construction materials of the structure governs ; c) GEO : Failure or excessive deformation of the ground where the strengths of soil or rock are significant in providing resistance ; d) FAT : Fatigue failure of the structure or structural members. NOTE For fatigue design, the combinations of actions are given in EN 1992 to EN 1995, EN 1998 and EN 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) 111

114 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April (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 f) HYD : hydraulic heave, internal erosion and piping in the ground caused by hydraulic gradients. NOTE See EN Verifications of static equilibrium and resistance Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause recommendation 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 112

115 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April (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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause (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) recommendation 1) Simplification that reduces to pure EQU 6.4.2(3)P 6.4.2(NOTE 1) 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. NOTE.1 Details for the methods STR and GEO are given in Annex A. 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. When favourable effects of actions are insignificant in comparison with the resistance (limit states STR and GEO), expression (6.7) reduces to: (6.9) NOTE.1 Partial factors for limit states STR+EQU, GEO+EQU, STR, GEO, and EQU are given in Annex A. 1) Simplification that reduces to pure STR and GEO Updated list according the list of limit states 113

116 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April (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 A1.3.1 Design values of actions in persistent and transient design situations Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 recommendation Updated reference expressions cross to 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) Persistent and transient design situations Permanent actions Unfavourable Favourable Leading variable action Accompanying variable actions Main (if any) Others Combine A1.2(A) and (B) Tables (6.10) γ G,j,sup G k,j,sup γ G,j,inf G k,j,inf γ Q,1 Q k,1 γ Q,i ψ 0,i Q k,i (6.10a) γ G,j,sup G k,j,sup γ G,j,inf G k,j,inf γ Q,1 ψ 0,1 Q k,1 γ Q,i ψ 0,i Q k,i (6.10b) ξγ G,j,sup G k,j,sup γ G,j,inf G k,j,inf γ Q,1 Q k,1 γ Q,i ψ 0,i Q k,i 114

117 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 Table A1.2(A) NOTE 1 NOTE 1 The γ values 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) Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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. recommendation 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 115

118 Clause EN 1990: A1:2004 incorporating corrigenda December 2008 and April 2010 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. Recommendations for the evolution of EN 1990 and notice of future possible changes to Clause 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 recommendation 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 116

119 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. 117

120 118

121 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) Draft 2013/02/27 Table A1.2(B) - Design values of actions (STR/GEO) (Set B) Persistent and transient design situations Permanent actions Leading variable action Unfavourable Favourable Main (if any) Accompanying variable actions (*) Persistent and transient design situations Permanent actions Leading variable action (*) Accompanying variable actions (*) Others Unfavourable Favourable Action Main Others (Eq. 6.10) γ Gj,sup G kj,sup γ Gj,inf G kj,inf γ Q,1 Q k,1 γ Q,i ψ 0,i Q k,i (Eq. 6.10a) γ Gj,sup G kj,sup γ Gj,inf G kj,inf γ Q,1 ψ 0,1 Q k,1 γ Q,i ψ 0,i Q k,i (Eq. 6.10b) ξγ Gj,sup G kj,sup γ Gj,inf G kj,inf γ Q,1 Q k,1 γ Q,i ψ 0,i Q k,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 γ Q = 0) when using expressions 6.10, or 6.10a and 6.10b γ Gj,sup = 1,35 (for the self-weight and permanent actions with low coefficient of variation up to 0,05 the values of partial factors γ Gj,sup may decreased up to 1,2) γ Gj,inf = 1,00 γ Q = 1,3 to 1,5 for imposed loads (γ Q = 1,5 for q < 2 kn/m 2, γ Q = 1,4 for 2 q < 5 kn/m 2, γ Q = 1,3 for q 5 kn/m 2 ) γ Sn = 1,5 to 1,8 for snow γ W = 1,5 to 1,7 for wind γ T = 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 ξγ Gj,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 γ G,sup if the total resulting action effect is unfavourable and γ G,inf if the total resulting Page 119

122 Draft 2013/02/27 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 γ G and γ Q may be subdivided into γ g and γ q and the model uncertainty factor γ Sd. A value of γ Sd in the range 1,05 to 1,15 can be used in most common cases and can be modified in the National annex. Page 120

123 Draft 2013/02/27 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 (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. K FI β Factor applicable to actions for reliability differentiation Reliability index Page 121

124 B.3. Consequences classes Draft 2013/02/27 (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 CC2 CC1 High consequence for loss of Grandstands, public buildings and human life, or very great infrastructure elements where the economic, social or environmental consequences of failure are high consequences Moderate consequence for loss of Residential and office buildings, human life, and considerable public buildings where the economic, social or environmental consequences of failure are consequences moderate Low consequence for loss of Agricultural buildings not normally human life, and small or negligible occupied economic, social or environmental consequences (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). Page 122

125 Draft 2013/02/27 Table B.2 Recommended target values for reliability index β (ultimate limit states) Reliability Class Target values for β 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 γ F 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 K FI, see Table B.3, may be applied to the partial safety factors of the persistent design situation. Table B.3 K FI factor for actions K FI factor for actions Reliability class RC1 RC2 RC3 K FI 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 K FI factors, which I should be applied to unfavourable actions only. (11) Alternatively, reliability differentiation may be applied using the partial safety factors for resistance γ M. 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 Page 123

126 Draft 2013/02/27 Table B.4 Structural classes (SC) depending on the complexity SC Characteristic Examples SC 1 SC 2 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 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) 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 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 Page 124

127 SC Characteristic Examples SC 3 Building works with structures of aboveaverage 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 Draft 2013/02/27 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 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 Page 125

128 SC Characteristic Examples Draft 2013/02/27 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. Page 126

129 Table B.5 Design checklevels (DCL) Design Check Level DCL3 Draft 2013/02/27 Characteristics Independent external systematic checking Minimum recommended requirements for checking of calculations, drawings and specifications 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 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 Table B.6 Inspection levels (IL) Inspection Level Characteristics Requirements Page 127

130 Draft 2013/02/27 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 CC3 Corresponding Reliability Class RC3 CC2 CC1 RC2 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 Page 128

131 Draft 2013/02/27 (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 RC 3 SC 3 DCL 3 IL 3 RC 2 SC 2 DCL 2 IL 2 RC 1 SC 1 DCL 1 IL 1 Corresponding Inspection Level for execution (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 Page 129

132 Draft 2013/02/27 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 and EN (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 CC3 Recurring inspections Periodically, every n years at least CC2 CC1 Periodically, and in the case of damage and defects relavant to safety 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: Page 130

133 Draft 2013/02/27 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. Page 131