Guidebook-1 Load Effects on Structures

Full text

(1)

(2)

(3)

(4)

(5) FOREWORD The Leonardo da Vinci Project CZ/08/LLP-LdV/TOI/134020 “Transfer of Innovations Provided in Eurocodes” addresses the urgent need to implement the new system of European documents related to design of construction works and products. These documents, called Eurocodes, are systematically based on the recently developed Council Directive 89/106/EEC “The Construction Products Directive” and its Interpretative Documents ID1 and ID2. Implementation of Eurocodes in each Member State is a demanding task as each country has its own long-term tradition in design and construction. The project should enable an effective implementation and application of the new methods for designing and verification of buildings and civil engineering works in all the partner countries (CZ, DE, ES, IT, NL) and in other Member States. The need to explain and effectively use the latest principles specified in European standards is apparent from various enterprises, undertakings and public national authorities involved in construction industry and also from universities and colleges. Training materials, manuals and software programmes for education are urgently required. The submitted Guidebook 1 is one of 2 upcoming guidebooks intended to provide required manuals and software products for training, education and effective implementation of Eurocodes: Guidebook 1: Load Effects on Buildings Guidebook 2: Load Effects on Bridges It is expected that the Guidebooks will address the following intents in further harmonisation of European construction industry: - reliability improvement and unification of the process of design; - development of a single market for products and for construction services; - new opportunities for trained primary target groups in the labour market. The Guidebook 1 is focused on determining load effects on buildings and industrial structures. The following main topics are treated in particular: - basic requirements on structures, - basis of structural design, - actions on buildings including accidental actions, - combination rules for load effects, - examples and case studies. Annex A to the Guidebook 1 provides a review of the basic statistical concepts used in design assisted by testing, Annex B a short description of general procedures used for assessment of existing structures and Annex C provides latest information on further development of Eurocodes. The Guidebook 1 is written in a user-friendly way employing only basic mathematical tools. Attached software products supplemented by a number of examples enable direct applications of general rules in practice. A wide range of potential users of the Guidebooks and other training materials includes practising engineers, designers, technicians, experts of public authorities, young people - high school and university students. The target groups come from all territorial regions of the partner countries. However, the dissemination of the project results is foreseen to be spread into all Member States of CEN and other interested countries. Prague 2009. 3.

(6)

(7) Contents. GUIDEBOOK 1 – BASIS OF DESIGN AND ACTIONS ON BUILDINGS CONTENTS Page FOREWORD CONTENTS 1 BASIC REQUIREMENTS Summary 1 Introduction 2 Basic requirements 2.1. Principal requirements 2.2 Requirements related to the permanent design situations 2.2 Requirements related to the accidental design situations 3 Reliability management 4 Design working life 5 Durability 6 Quality management References Appendix A Reference documents A.1. Introduction A.2. Construction Product Directive A.3. Interpretative document No. 1 Mechanical resistance and stability A.4. Guidance Paper L. 3 5 11 11 11 12 12 13 13 14 15 16 17 18 19 19 19 20 23. 2 BASIS OF DESIGN – GENERAL PRINCIPLES Summary 1 Introduction 1.1. Background documents 1.2 General principles 2 Historical development 2.1 Uncertainties 2.2 Definition of reliability 2.3 Development of design methods 3 Basic concepts of EN 1990 3.1 Design working life and design situation 3.2 Limit states 3.3 Ultimate limit states 3.4 Serviceability limit states 4 Verification of limit states 4.1 Verification of static equilibrium and strength 4.2 Verification of the serviceability limit states 5 Concluding remarks Reference Appendix A A reinforced concrete slab – various design concepts A.1 Introduction A.2 A reinforced concrete slab A.3 Design and reliability consideration A.4 Concluding remarks. 32 32 32 32 32 33 33 34 35 37 37 37 40 41 42 42 43 43 44 45 45 45 45 47. 5.

(8) Contents. 3 RELIABILITY DIFFERENTIATION Summary 1 Introduction 1.1. Background documents 1.2 General principles 2 Basic reliability elements 3 Target reliability in the Eurocodes 3.1 General 3.2 Reliability classes 3.3 Variation with time – Discussion 3.4 Global failure – robustness 3.5 Existing structures 4 Partial safety factors 4.1 Derivation based on reliability methods 4.2 Simplified reliability differentiation (Annex B of EN 1990) 5 Examples 5.1 Residential steel building 5.2 Agricultural steel building 5.3 Agricultural concrete building 6 Concluding remarks References Appendix A: Risk Acceptance Approaches in Codes A.1 General A.2 Human safety A.3 Calibration A.4 Cost – benefit approach References. 48 48 48 48 48 49 50 50 50 51 53 53 51 54 55 56 56 56 56 57 57 58 58 58 59 60 61. 4 ACTIONS Summary 1 Introduction 1.1 Background documents 2 Actions and effects of actions 2.1 Definitions of actions 2.2 Effect of actions 3 Classification of actions 3.1 General 3.2 By their variation in time 3.3 By their origin 3.4 By their variation in space 3.5 By their nature or structural response 3.6 Bounded and unbounded actions 3.7 Environmental influences 4 Reference period and distribution of maxima 4.1 Climatic actions 4.2 Imposed actions 5 Characteristic values 5.1 General 5.2 Permanent actions. 62 62 62 62 62 62 63 65 65 65 65 65 65 66 66 66 66 67 69 69 69. 6.

(9) Contents. 6. 7 8 9. 5.3 Variable actions 5.4 Imposed loads 5.5 Snow loads 5.6 Wind loads 5.7 Thermal actions Representative values 6.1 General 6.2 The combination value of a variable action 6.3 The frequent value of a variable action 6.4 The quasi-permanent value of a variable action Representation of dynamic actions Representation of fatigue actions Representation of environmental influences References. 70 71 73 76 81 83 83 83 83 83 84 85 85 85. 5 ACCIDENTAL ACTIONS Summary 1 Introduction 1.1. History 1.2 Background documents 2 Eurocode approach 3 Design for impact and explosion loads 3.1 Impact from vehicles 3.2 Loads due to explosions 3.3 Design example of a column in a building for an explosion 4 Robustness of building 4.1 Background 4.2 Summary of design rules 4.2.1 Design Rules for Class 2, Lower Group, Framed structures 4.2.2 Rules for Class 2, Lower group, Load-bearing wall construction 4.2.3 Rules for Class 2, Upper Group, Framed structures 4.2.4 Rules for Class 2, Upper Group, Load-bearing wall construction 4.3 Example structures 4.3.1 Framed structure, Consequences class 2, Upper Group 4.3.2 Wall structure, Consequences class 2, Upper Group 5 Conclusions References Appendix A: Methodology related to robustness assessment A.1 Conditional probability of collapse A.2 Quantification of robustness A.3 Basic design philosophy References Appendix B: Impact Force Analysis. 86 86 86 86 87 87 90 90 90 91 94 94 94 94 95 95 95 96 96 96 97 97 98 98 99 100 101 102. 6 COMBINATION RULES IN EUROCODES Summary 1 Introduction 1.1. Background documents 1.2 General principles 2 Combination of actions. 103 103 103 103 103 104. 7.

(10) Contents 2.1 General 2.2 Combinations of actions in persistent and transient design situations 2.3 Combination of actions for accidental and seismic design situations 2.4 Combination of actions for serviceability limit states 3 Examples 3.1 Cantilivered beam 3.2 Continuous beam of three spans 3.3 Cantilivered frame 3.4 Three bay two-dimensional frame 4 Concluding remarks References Appendix A: Alternative load combinations for the cantilevered beam. 104 104 105 106 106 106 110 113 118 122 122 123. 7 ACTIONS IN TRANSIENT DESIGN SITUATIONS Summary 1 Introduction 1.1. Background documents 1.2 General principles 2 Design situations during execution 2.1. Design situations 2.2 Nominal duration of design situations 3 Representative and design values of actions during execution 4 Combinations of actions 5 Actions during execution 6 Annex A for buildings and bridges 6.1. Annex A1 Supplementary rules for buildings 6.2 Annex A2 Supplementary rules for bridges 7 Annex B for Actions on structures during alteration, rehabilitation or demolition 8 Concluding remarks References. 125 125 125 125 125 125 125 126 128 129 129 131 131 131. 8 ACTIONS AND COMBINATION RULES FOR SILOS AND TANKS Summary 1 Introduction 1.1. Background documents 1.2 Basic principles 2 Design situations 3 Actions on silos and tanks 3.1 Types of actions 3.2 Actions specific on silos 4 Classification of silos 5 Combinations of actions for silos 5.1 Combinations of actions in persistent design situations 5.2 Combinations of actions in accidental design situations 5.3 Combinations of actions in seismic design situations 5.4 Combinations of actions in serviceability limit states 6 Combinations of actions for tanks 6.1 Actions 6.2 Combinations of actions. 134 134 134 134 134 135 136 136 136 137 137 137 138 139 139 140 140 140. 8. 131 132 133.

(11) Contents 7. An example of slender silo 7.1 Introduction 7.2 Symmetrical filling loads on vertical walls 7.3 Filling patch load 7.4 Symmetrical discharge load 7.5 Discharge patch load Concluding remarks References. 140 140 141 143 144 145 145 145. 9 LOAD EFFECTS IN STRUCTURAL MEMBERS Summary 1 Introduction 1.1 Background documents 1.2 General principles 2 Verification of static equilibrium and strength 3 Verification of serviceability limit states 4 Examples 4.1 Cantilevered beam 4.2 Continuous beam of three spans 4.3 Cantilevered frame 5 Concluding remarks References. 147 147 147 147 147 148 149 149 149 153 156 161 161. 10 DESIGN OF A REINFORCED CONCRETE BUILDING ACCORDING TO EUROCODES Summary 1 Introduction 2 The building 3 Actions, loadings and load combinations 3.1 Density and self-weight 3.2 Imposed loads 3.3 Snow load 3.4 Wind actions 3.5 Load combinations for ULS verifications 3.6 Load combinations and limitations for SLS verifications 4 Materials 4.1 Stress-strain diagrams 5 Results of the structural analysis 6 Static verification examples 6.1 Verification of the first floor beams 6.2 Verification of the corner column 7 Concluding remarks References Appendix to Chapter 10 A.1 Basic structural drawings of the building. 162 162 162 162 164 164 164 164 165 167 168 169 170 170 172 172 174 174 175 176 176. ANNEX A: DESIGN ASSISTED BY TESTING Summary 1 Introduction 2 Statistical determination of a single property. 185 185 185 185. 8. 9.

(12) Contents. 3. 2.1 General principles 2.2 Assessment based on the characteristic value 2.3 Direct assessment of the design value Statistical determination of resistance models 3.1 General procedure 3.2 An example of a concrete slab References. 185 186 187 188 188 191 192. ANNEX B: ASSESSMENT OF EXISTING STRUCTURES Summary 1 Introduction 2 Principles and general framework of assessment 3 Investigation 4 Basic variables 5 Evaluation of inspection results 6 Structural analysis 7 Verification 8 Assessment in the case of damage 9 Final report and decision 10 Numerical example 10.1 Updating of failure probability 10.2 Bayesian method for fractile estimation 11 Concluding remarks References. 193 193 193 194 197 198 199 200 202 202 203 204 204 205 207 208. ANNEX C: FURTHER DEVELOPMENT OF EUROCODES Summary 1 Introduction 2 New CPR and sustainable constructions 3 Evolution of Eurocodes 3.1 Maintenance 3.2 Harmonization 3.3 Promotion 3.4 Further developments 4 Research for further development of Eurocodes References. 209 209 209 210 211 211 211 212 213 214 214. 10.

(13) Chapter 1: Basic requirements. CHAPTER 1: BASIC REQUIREMENTS Angel Arteaga1, Ana de Diego1 and Albert Alzate1 1. E. Torroja Institute of Construction Sciences, CSIC. Madrid. Spain. Summary The Eurocodes system determines a set of basic requirements that all the structures have to fulfil in order to adequate the structure to its foreseen use and expected live. These requirements, based on European Commission Directives and other documents, are revised and explained in this chapter.. 1.. INTRODUCTION. When a Member State joints the European Union (EU), it transfers some of its competencies to the European Commission. The European Commission publishes a lot of Directives that the Member States should adopt. The competencies referring to the level of safety at each country in all the fields, and in construction works in particular, are not transferred to EU; that means that each state is allowed to determine the level of safety applicable inside the country, and, therefore, the reliability level of its construction works. In the field of construction, the European Commission delivered the Construction Products Directive (CPD) [1], compulsory to the Member States, indicating the conditions needed to facilitate the free circulation of the construction products in the European market (not only for European products). Furthermore, there is a wish in harmonizing all the design procedures and values in a way that all the construction products and building companies can move easily all around the EU. The CPD states in its Annex I the six so-called essential requirements: 1. Mechanical resistance and stability 2. Safety in case of fire 3. Hygiene, health and the environment 4. Safety in use 5. Protection against noise 6. Energy economy and heat retention The Eurocode structural system only deals with the two firsts of these six requirements. In this Guidebook only the first, Mechanical resistance and stability, will be treated. These requirements are complemented by the other EC documents known as Interpretative Documents No. 1 (ID-1) [2] to Interpretative Documents No 6 (ID-6), each one dealing with and explaining in detail the corresponding requirement, and the Guidance Paper L [3], which defines the use of EN Eurocodes for structural design of works and in technical specifications for structural products, and also the future actions related to the Eurocode Programme.. 11.

(14) Chapter 1: Basic requirements. The main points of the CPD, ID-1, and the Guidance Paper L mentioned above are summarized in the Annex A of this Chapter.. 2.. BASIC REQUIREMENTS. 2.1.. Principal requirements. The essential Requirements 1 and 2, stated in the CPD and developed in the Interpretative Documents ID-1 and ID-2, indicated above, are translated into clauses in the Section 2 Requirements of the Eurocode EN 1990: Basis of structural design [9]. The first requirement: Mechanical resistance and stability is summarized in the first two clauses: (1)P A structure shall be designed and executed in such a way that it will, during its intended life, with appropriate degrees of reliability and in an economical way sustain all actions and influences likely to occur during execution and use, and remain fit for the use for which it is required. (2)P A structure shall be designed to have adequate: structural resistance, serviceability, and durability. The third clause corresponds to the second Essential Requirement: Safety in case of fire. (3)P In the case of fire, the load-bearing capacity of the structure shall be assured for the required period of time. In order to understand adequately this content, it should be distinguished, and so does the Eurocode, between what is referred to the transient, permanent and accidental design situations. Permanent design situations are those affecting the structure at most part of its working life, taking into account aspects related with the safety –structural resistance–, i.e.: Ultimate Limit State (ULS); and with serviceability; i.e.: Serviceability Limit State (SLS); and also with the durability; that is, the structural conditions that limit the deterioration of the structure not influencing its performance. Transient design situations are relevant during a period much shorter than the design working life of the structure. They refer to temporary conditions of the structure, of use, or exposure, e.g. during construction, repair or upgrading. Therefore, taking into account the permanent and transient design situations, a structure shall be designed, in a way that: – sustains all actions and influences likely to occur during execution and use, and – remains fit for the use for which it is required. Accidental situations are those situations which are foreseeable to occur, but with a small probability, during the working life of the structure. In case of accidental design situations the EN 1990 [9] states: A structure shall be designed and executed in such a way that it will not be damaged by events such as: – explosion, – impact, – and the consequences of human errors, to an extent disproportionate to the original cause.. 12.

(15) Chapter 1: Basic requirements. 2.2.. Requirements related to the permanent design situations. First, it should be noted that the Eurocode system is mainly focused on the conditions that the designer of the structures must take into account. For this reason the Clause 2.1 reads that the structure shall be designed, and executed; nothing is indicated in this clause about the way the structure should be maintained. But the adequate use and maintenance of the structure is fundamental for fulfilling these requirements. Therefore, other documents related with the buildings or civil works must deal with these aspects. Other important point is what means the so-called intended life, that is: the period of time the structure is designed to fulfil its functions. This point is treated later in more detail. The terms with appropriate degrees of reliability and in an economical way will indicate the necessary trade-off between safety and economy. That is: the probability that the structure fails to fulfil the requirements and the cost of building and maintenance of the structure. As a first approach, a safer structure will require more detailed design, more material (bigger sections), and/or more quality control in all the stages, therefore an increment in the cost of execution of the work. The designer and owner have to balance this increment of cost with the increase of safety, taking into account, in any case, the minimum safety requirement determined in the country (not in the Eurocodes). The designer must take into account that the structure has to sustain all actions and influences likely to occur during execution and use; that is: the adequate behaviour taking into account the Ultimate limit states, and at the same time has to remain fit for the use for which it is required, the Serviceability Limit States. Each type of foreseeable failure of the structure and/or its members will correspond to different ULS: bending, shear, buckling, etc.; or SLS: cracks, deformations, sensibility to vibrations, etc.; and will correspond to a different Limit State Function; that is, the relationship (in general in mathematical form) between the actions or the effect of actions and the resistances of the structural material at the member considered that divides the safe and unsafe states of the structure or member. The Eurocodes give the way to determine the equations and the design values of the actions and resistances to be applied. These two requirements are interrelated: traditionally one structure safe enough – fulfilling the ULS requirements – was, normally, also stiff enough and it did not have serviceability problems. Nowadays, the situation is just the opposite: new materials with much higher resistance, and no stiffer in the same proportion and new design methods, yield to slender elements, therefore more deformable structures, what is the origin of frequent pathologies in the structures. It could be said now that one structure stiff enough is, probably, safe enough. 2.3. Requirements related to the accidental situations For the design of a structure, an accidental action is a type or value of one action that is foreseeable to occur in the lifetime of the structure, but not likely; let´s say, it has a probability of 10-4 of occurrence during its working life. Possible accidental actions are not only those considered in the EN 1990 [9]: gas explosion, impact, and consequences of human gross errors. The above-indicated ones are those for which the Eurocode 1 Part 1-7: General Actions - Accidental actions [10] gives further guidance. Other possible accidental actions are, for instance: winds or snows in a magnitude greater than foreseeable taking account the existing statistics, other type of explosions, plane crash, etc. In any case, voluntary actions as arson, terrorism, etc., are excluded from the Eurocodes. Nevertheless, the general guidance given in EN 1991-1-7 [10] can be useful even in these cases.. 13.

(16) Chapter 1: Basic requirements. Conceptually, seismic actions or fire actions are also accidental actions, but due to their particular importance and specific way of making calculations there are specific Eurocodes devoted to them. The philosophy of the Eurocodes to deal with the accidental actions is that it is not needed to design the structure in a way to sustain these extreme actions without damage. Some damage is acceptable, but not to an extent disproportionate to the original cause. That is: for the sake of example, an impact of a vehicle to a column could cause the failure of this column and the surrounding floors, but not of the whole structure. Different strategies can be used to face accidental situations. Recommendations are given in EN 1990 and also in EN 1991-1-7 [10] to avoid excessive damage. Potential alternative or concurrent strategies include: - avoiding, eliminating or reducing the hazards to which the structure can be subjected; - selecting a structural form which has low sensitivity to the hazards considered; - selecting a structural form and design that can survive adequately the accidental removal of an individual member or a limited part of the structure, or the occurrence of acceptable localised damage; - avoiding as far as possible structural systems that can collapse without warning; - tying the structural members together. Chapter 5 of this Guidebook deals with these situations in detail.. 3. RELIABILITY MANAGEMENT Evidently neither all the structures, nor every part of a structure, have the same level of reliability, and even, for each member it also will depend on the type of the studied effect; i.e.: the different limit state. It is not the same to analyze the failure due to the buckling of columns (ULS) or the apparition of a crack of determined size (SLS). Indications of the adequate level of reliability for different circumstances are given in Section 2 of EN 1990 [9]. The concept of risk analysis is not highlighted in this section, but it is clear that it is behind all that was indicated here. The term risk is assumed to be the product of the consequences derived from an event and the probabilities that the event occurs; i.e. the probabilities of reaching that limit state or, in other words, the level of reliability. The important point is to keep the risk at an acceptable level. Unfortunately, it is easy to say ‘to keep the risk at acceptable level’, but not so easy to verify it in practical applications. Because both terms of the statement present important uncertainties. Firstly, as it is difficult to quantify the existing risk, a comprehensive set of scenarios encompassing all significant events has to be analysed. And, secondly, the exact knowledge of what is a quantified ‘acceptable’ level of risk is hardly to be achieved. In practical applications, the codes, and so do the Eurocodes, assume an implicit acceptable risk and, for each Limit State, assume, also, a level of average foreseeable consequences. With these assumptions in mind, the codes determine the ‘acceptable’ probabilities of failure for each Limit State (both ULS and SLS); that is: the level of reliability. For these considerations it is clear that the higher are the consequences of the failure the higher has to be the level of reliability. In all the calculations it is assumed that the design is developed following the Eurocodes 1990 to 1999 and taking care of appropriate execution and quality management measures.. 14.

(17) Chapter 1: Basic requirements. The cost and procedures necessary to reduce the risk of failure are other important factors to be taken into account for the choice of the adequate level of reliability. An example will clarify this concept: If we are evaluating an existing structure and we work out that a statically determined beam, according to the normal design procedures, would need to be reinforced with six steel bars diameter of 25 mm, but actually it has only five bars of that diameter; that is, it would need to be supplemented with one more bar. The evaluator, due to the fact that supplementing a beam with one additional bar is quite expensive - not for the cost of the steel, but for the cost of the implementation - could probably accept the small decrease of the reliability level. Exactly the same design problem, but in a case when dealing with a structure in the design phase, still not built, would probably lead to a modification of the drawing by adding a new bar, because the cost is much lower in this case. The adequate reliability is not only reached by means of designing structures with great resistance, but also by means of preventative and protective measures. Those are measures that decrease the probability of occurrence of the event taken in consideration or the consequences of the failure of the structure (e.g. implementation of safety barriers, active and passive protective measures against fire, protection against corrosion such as painting or cathodic protection, etc.) or an adequate quality management for reducing errors in design and execution of the structure, and gross human errors. In order to decrease the consequences of the failure other aspects can be taken into account: – the degree of robustness (structural integrity): interactions between the members of the structure in such a way that the failure of one member does not yield to the failure of the structure as a whole. See Chapter 5 of this Guidebook; – the choice of the design working life of the structure and its elements that could be different, with possible different plans for maintenance and replacement; – the extent and quality of preliminary investigations of soils and possible environmental influences; – the accuracy of the mechanical models used; – the detailing; – adequate inspection and maintenance according to procedures specified in the project documentation; – measures relating to design calculations: translating the adequate probability of failure into the choice of: – representative values of actions; – the values of the partial factors. This subject is more deeply treated and focused in practical applications in the Chapters 2 and 3 of this Guidebook: ‘Basis of design - General principles’ and ‘Reliability differentiation’.. 4. DESIGN WORKING LIFE Design working life is the assumed period for which a structure or part of it is to be used for its intended purpose with anticipated maintenance but without major repair being necessary. All the structural calculations based on probabilities must be referred, implicitly or explicitly, to relevant design working life. The choice of the value of design working life is basic for the design process of the structure. It will affect not only aspects of the required durability of the structure, but also the design values of the actions to be considered. The longer is the time period the bigger probabilities of reaching higher values of the actions should be considered.. 15.

(18) Chapter 1: Basic requirements. The choice of design working life will depend on the economic or social importance of the structure. Indicative values are given for different types of civil and building structures in EN 1990 [9]. More detailed information may be given in the National Annex. For each particular case, the design working life can be established by an agreement between the owner, the National Authorities and the designer. Structures not included in the scope of the Eurocodes (e.g. dams, tunnels, nuclear power plants, etc.) could be designed for different design working lives, even longer than those indicative values given in Table 1. Table 1: Indicative design working life Design working life category 1 2. Indicative design working life (years) 10 10-25. Examples. Temporary structures (1) Replaceable structural parts, e.g. gantry girders, bearings 3 15-30 Agricultural and similar structures 4 50 Building structures and other common structures 5 100 Monumental building structures, bridges, and other civil engineering structures (1) Structures or parts of structures that can be dismantled with a view of being re-used should not be considered as temporary.. 5. DURABILITY The ISO/DIS 13823 [8] defines the term durability as: the capability of a structure or any component to satisfy with planned maintenance the design performance requirements over a specified period of time under the influence of the environmental actions, or as a result of a self-ageing process. Structures, as everything, deteriorate with time adversely influencing their performance. There are multiple actions affecting the durability of the structure depending mainly on its materials. The most important of them refer to presence of water moisture with or without contaminants. The rate of deterioration depends on the environmental conditions, the chosen materials and the quality in the design, execution and maintenance. The requirement in this point is that the structure shall be designed so 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. In this point, maintenance has to be understood as the total set of activities (including inspection, cleaning and repair) performed during the design service life of a structure to preserve the appropriate structural performance [8]. In order to achieve an adequately durable structure, the following should be taken into account: – the intended or foreseeable use of the structure; – the required design criteria; – the expected environmental conditions; – the composition, properties and performance of the materials and products; – the properties of the soil;. 16.

(19) Chapter 1: Basic requirements. – – – – –. the choice of the structural system; the shape of members and the structural detailing; the quality of workmanship, and the level of control; the particular protective measures; the intended maintenance during the design working life. The Figure 1, adopted from [6] gives an indication on how a structure can perform in time. We can take the performance as a quantitative variable defining the behaviour of the structure. Once the structure is in use (even before), it starts to deteriorate, and, therefore, to decrease the value of the chosen variable ‘performance’. If we do not take any other measure that the normal maintenance, the performance after a time, longer or shorter, will reach the nominal Serviceability Limit State (SLS), defining what would be the actual working life of the structure. If, even in this point, no measures are taken, the structure will keep on deteriorating reaching the Ultimate Limit State (ULS) and, eventually, the actual failure of the structure. If repairs are undertaken in some points in time of the working life of the structure, before the SLS is reached, punctual increases of the performance value can be obtained, in general the performance will keep under the original value, allowing to have a longer working life for the structure.. Figure 1. Working life with and without repairs. 6. QUALITY MANAGEMENT Quality management has three main components: quality control, quality assurance and quality improvement. Quality management is focused not only on product quality, but also the means to achieve it. The structure as built has to fulfil all the requirements and the assumptions adopted in the design phase. To assure this, appropriate quality management measures should be in place. These measures comprise:. 17.

(20) Chapter 1: Basic requirements. – definition of the reliability requirements, – organisational measures and – controls at the stages of design, execution, use and maintenance.. REFERENCES [1] Construction Products Directive (Council Directive 89/106/EEC) . European Commission, Enterprise Directorate-General, 2003 http://ec.europa.eu/enterprise/construction/internal/cpd/cpd.htm [2] Interpretative document No. 1: Mechanical resistance and stability. European Commission, Enterprise Directorate-General, 2004 http://ec.europa.eu/enterprise/construction/internal/intdoc/idoc1.htm [4] Guidance Paper L (concerning the Construction Products Directive - 89/106/EEC) Application and Use of Eurocodes: European Commission, Enterprise Directorate-General, 2004. http://ec.europa.eu/enterprise/construction/internal/guidpap/europart1.htm [5] Handbook 1. Basis of Structural Design. Leonardo da Vinci Pilot Project CZ/02/B/F/PP134007. Gaston, UK. 2004 [6] Gulvanessian, H., Calgaro, J.-A., Holický, M.: Designer's Guide to EN 1990, Eurocode: Basis of Structural Design; Thomas Telford, London, 2002, 192 pp. [7] ISO 834 Part 1 [8] ISO/DIS 13823, general Principles on the Design of Structures for Durability, Geneva 2006 [9] EN 1990 Eurocode: Basis of structural design. European Committee for Standardisation, 04/2002. [10] EN 1991-1-7 Eurocode 1: Actions on structures – Part 1-1: General actions – Accidental actions, European Committee for Standardisation, 2006.. 18.

(21) Chapter 1: Basic requirements. APPENDIX A: REFERENCE DOCUMENTS A.1 Introduction In order to better understand what the Essential Requirements express, the most important items of the documents and their backgrounds are described as follows. The full text of the documents can be easily obtained from the European Committee web page indicated in the references. A.2 Construction Products Directive The construction products directive (Council Directive 89/106/EEC) Council Directive 89/106/EEC of 21 December 1988 on the approximation of laws, regulations and administrative provisions of the Member States relating to construction products (89/106/EEC) (OJ L 40, 11.2.1989, p.12) amended by: Council Directive 93/68/EEC of 22 July 1993 (OJ L 220, 30.8.1993, p.1) and Regulation (EC) No 1882/2003 of the European Parliament and of the Council of 29 September 2003 (OJ L 284, 31.10.2003, p.1) A.2.1 Annex I: Essential requirements The products must be suitable for construction works, which (as a whole and in their separate parts) are fit for their intended use, account being taken of economy, and in this connection satisfying the following essential requirements where the works are subjected to regulations containing such requirements. Such requirements shall, under normal maintenance, be satisfied for an economically reasonable working life. The requirements generally concern actions which are foreseeable. Mechanical resistance and stability The construction works must be designed and built in such a way that the loadings that are liable to act on it during its constructions and use will not lead to any of the following: (a) collapse of the whole or part of the work; (b) major deformations to an inadmissible degree; (c) damage to other parts of the works, fittings or installed equipment due to deformation of the load-bearing structures; (d) damage by an event to an extent disproportionate to the original cause. Safety in case of fire The construction works must be designed and built in such a way that in the event of an outbreak of fire: - the load-bearing capacity of the construction can be assumed for a specific period of time, - the generation and spread of fire and smoke within the works are limited, - the spread of the fire to neighbouring construction works is limited, - occupants can leave the works or be rescued by other means. - the safety of rescue teams is taken into consideration. Hygiene, health and the environment The construction work must be designed and built in such a way that it will not be a threat to the hygiene or health of the occupants or neighbours, in particular as a result of any of the following: - the giving-off toxic gas, - the presence of dangerous particles or gases in the air. - the emission of dangerous radiation. 19.

(22) Chapter 1: Basic requirements. - pollution or poisoning of water or soil, - faulty elimination of waste water, smoke, solid or liquid wastes, - the presence of damp in parts of the works or on surfaces within the works. Safety in use The construction work must be designed and built in such a way that it does not present unacceptable risks of accidents in service or in operation such as slipping, falling, collision, burns, electrocution, injury from explosion. Protection against noise The construction works must be designed and built in such a way that noise perceived by the occupants or people nearby is kept down to a level that will not threaten their health and will allow them to sleep, rest and work in satisfactory conditions. Energy economy and heat retention The construction works and its heating, cooling and ventilation installations must be designed and built in such a way that the amount of energy required in use shall be low, having regard to the climatic conditions of the location and the occupants. A.3 Interpretative document No. 1 Mechanical resistance and stability A.3.1 Purpose and scope of Interpretative document No. 1 (1) This Interpretative Document relates to Council Directive 89/106/EEC of 21 December 1988 on the approximation of laws, regulations and administrative provisions of the Member States relating to construction products, hereinafter referred to as “the Directive”. (2) Article 3 of the Directive stipulates that the purpose of the Interpretative Documents is to give concrete form to the essential requirements for the creation of the necessary links between the essential requirements set out in Annex I to the Directive and the mandates for the preparation of harmonized standards and guidelines for European technical approvals or the recognition of other technical specifications within the meaning of Articles 4 and 5 of the Directive. Where considered necessary, the provisions of this Interpretative Document will be further specified in each particular mandate. In drafting the mandates, account will be taken, if necessary, of the other essential requirements of the Directive, as well as of other relevant Directives concerning construction products. (3) This Interpretative Document deals with the aspects of the works where “Mechanical resistance and stability” may be concerned. It identifies products or product families and characteristics relating to their satisfactory performance. “The construction works must be designed and built in such a way that the loadings that are liable to act on it during its construction and use will not lead to any of the following: a) collapse of the whole or part of the works; b) major deformations to an inadmissible degree; c) damage to other parts of the works or to fittings or installed equipment as a result of major deformation of the load-bearing construction; d) damage by an event to an extent disproportionate to the original cause.”. 20.

(23) Chapter 1: Basic requirements. 4) In accordance with the Council Resolution of 7 May 1985 (New Approach) and the preamble of the Directive, this interpretation of the essential requirement is intended not to reduce the existing and justified levels of protection for works in the Member States. A.3.2 Meaning of the general terms used in the Interpretative documents. Construction works Construction works means everything that is constructed or results from construction operations and is fixed to the ground. This term covers both buildings and civil engineering works. In the Interpretative Documents "construction works" are also referred to as the "works". Construction works include for example: dwellings; industrial, commercial, office, health, educational, recreational and agricultural buildings; bridges; roads and highways; railways; pipe networks; stadiums; swimming pools; wharfs; platforms; docks; locks; channels; dams; towers; tanks; tunnels; etc. Construction products (1) This term refers to products which are produced for incorporation in a permanent manner in the works and placed as such on the market. The terms "construction products" or "products", where used in the Interpretative Documents, include materials, elements and components (single or in a kit) of prefabricated systems or installations which enable the works to meet the essential requirements. (2) Incorporation of a product in a permanent manner in the works means: - that its removal reduces the performance capabilities of the works; and - that the dismantling or the replacement of the product are operations which involve construction activities. Normal maintenance (1) Maintenance is a set of preventive and other measures which are applied to the works in order to enable the works to fulfil all its functions during its working life. These measures include cleaning, servicing, repainting, repairing, replacing parts of the works where needed, etc. (2) Normal maintenance generally includes inspections and occurs at a time when the costs of the intervention which has to be made are not disproportionate to the value of the part of the works concerned, consequential costs being taken into account. Intended use The intended use of a product refers to the role(s) that the product is intended to play in the fulfilment of the essential requirements. Economically reasonable working life (1) The working life is the period of time during which the performance of the works will be maintained at a level compatible with the fulfilment of the essential requirements. (2) An economically reasonable working life presumes that all relevant aspects are taken into account, such as: - costs of design, construction and use; - costs arising from hindrance of use; - risks and consequences of failure of the works during its working life and costs of insurance covering these risks; - planned partial renewal; - costs of inspections, maintenance, care and repair; - costs of operation and administration;. 21.

(24) Chapter 1: Basic requirements. - disposal; - environmental aspects. Actions Actions which may affect the compliance of the works with the essential requirements are brought about by agents acting on the works or parts of the works. Such agents include mechanical, chemical, biological, thermal and electro-magnetic agents. Performance Performance is a quantitative expression (value, grade, class or level) of the behaviour of a works, part of the works or product, for an action to which it is subject or which it generates under the intended service conditions (for the works or parts of works) or intended use conditions (for products). A.3.3. Basis for verification of the satisfaction of the essential requirement "Mechanical resistance and stability". General (1) This chapter identifies basic principles prevailing in Member States for the verification of the satisfaction of the essential requirement "Mechanical resistance and stability". These principles are currently complied with when and where the works are subject to regulations containing this essential requirement. (2) The essential requirement, as far as applicable, is satisfied with acceptable probability during an economically reasonable working life of the works. (3) The satisfaction of the essential requirement is assured by a number of interrelated measures concerned in particular with: - the planning and design of the works, the execution of the works and necessary maintenance; - the properties, performances and use of the construction products. (4) It is up to the Member States, when and where they feel it necessary, to take measures concerning the supervision of planning, design and execution of the works, and concerning the qualifications of parties and persons involved. Where this supervision and this control of qualifications are directly connected with the characteristics of products, the relevant provisions shall be laid down in the context of the mandate for the preparation of the standards and guidelines for European technical approval related to the products concerned. A.3.4. Working life and durability. 1 Treatment of working life of construction works in relation to the essential requirement (1) It is up to the Member States, when and where they feel it necessary, to take measures concerning the working life which can be considered reasonable for each type of works, or for some of them, or for parts of the works, in relation to the satisfaction of the essential requirements. (2) Where provisions concerning the durability of works in relation to the essential requirement are connected with the characteristics of products, the mandates for the preparation of the European standards and guidelines for European technical approvals, related to these products, will also cover durability aspects.. 22.

(25) Chapter 1: Basic requirements. A.4 GUIDANCE PAPER L A.4.1. Eurocodes Part 1: General 1.1 Aims and benefits of the Eurocode programme The Eurocodes provide common design methods, expressed in a set of European standards, which are intended to be used as reference documents for Member States to: – prove the compliance of building and civil engineering works or parts thereof with Essential Requirement n°1 Mechanical resistance and stability (including such aspects of Essential Requirement n°4 Safety in use, which relate to mechanical resistance and stability) and a part of Essential Requirement n°2 Safety in case of fire, including durability, as defined in Annex 1 of the CPD – express in technical terms these Essential Requirements applicable to the works and parts thereof; – determine 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 accompanying CE marking (e.g. declared values). 1.1.2 EN Eurocodes are intended by the European Commission services, and the Member States, to become the European recommended means for the structural design of works and parts thereof, to facilitate the exchange of construction services (construction works and related engineering services) and to improve the functioning of the internal market. 1.1.3 The intended benefits and opportunities of Eurocodes are to: provide common design criteria and methods to fulfil the specified requirements for mechanical resistance, stability and resistance to fire, including aspects of durability and economy, provide a common understanding regarding the design of structures between owners, operators and users, designers, contractors and manufacturers of construction products facilitate the exchange of construction services between Members States, facilitate the marketing and use of structural components and kits in Members States, facilitate the marketing and use of materials and constituent products, the properties of which enter into design calculations, in Members States, be a common basis for research and development, in the construction sector, allow the preparation of common design aids and software, increase the competitiveness of the European civil engineering firms, contractors, designers and product manufacturers in their world-wide activities. 1.2 Background of the Eurocode programme 1.3 Objectives of the Guidance Paper 1.3.1 This Guidance Paper expresses, with the view of achieving the aims and benefits of the Eurocode programme mentioned in 1.1, the common understanding of the Commission and the Member States on: The application of EN Eurocodes in the structural design of works (chapter 2). The use of EN Eurocodes in harmonised standards and European technical approvals for structural construction products (chapter 3). A distinction is made between: 23.

(26) Chapter 1: Basic requirements. a) products with properties which enter into structural calculations of works, or otherwise relate to their mechanical resistance and stability, including aspects of durability and serviceability, and which for this reason should be consistent with the assumptions and provisions made in the EN Eurocodes ("structural materials" are the most concerned - see chapter 3.2) b) products with properties which can directly be determined by methods used for the structural design of works, and thus should be determined according to the EN Eurocode methods (prefabricated "structural components and kits" are the most concerned - see chapter 3.3). A.4.2. Eurocodes Part 2: Use of EN Eurocodes for structural design of works 2.1 National Provisions for the structural design of works 2.1.1 The determination of the levels of safety [The word safety is encompassed in the Eurocodes in the word reliability] of buildings and civil engineering works and parts thereof, including aspects of durability and economy [The introductory provisions of Annex I of the CPD lay down: "The products must be suitable for construction works which (as a whole and in their separate parts) are fit for their intended use, account being taken of economy, and in this connection satisfy the following essential requirements where the works are subject to regulations containing such requirements. Such requirements must, subject to normal maintenance, be satisfied for an economically reasonable working life. The requirements generally concern actions which are foreseeable." Economic aspects remain within the competence of the Member States. 2.1.2 Possible differences in geographical or climatic conditions (e.g. wind or snow), or in ways of life, as well as different levels of protection that may prevail at national, regional or local level in the sense of article 3.2 of the CPD. 2.1.3 When Member States lay down their Nationally Determined Parameters, they should: choose from the classes included in the EN Eurocodes, or use the recommended value, or choose a value within the recommended range of values, for a symbol where the EN Eurocodes make a recommendation, or when alternative methods are given, use the recommended method, where the EN Eurocodes make a recommendation, take into account the need for coherence of the Nationally Determined Parameters laid down for the different EN Eurocodes and the various Parts thereof. Member States are encouraged to co-operate in minimising the number of cases where recommendations for a value or method are not adopted for their nationally determined parameters. By choosing the same values and methods, the Member States will enhance the benefits listed in 1.1.3. 2.1.4 The Nationally Determined Parameters laid down in a Member State should be made clearly known to the users of the EN Eurocodes and other parties concerned, including manufacturers. 2.1.5 When the EN Eurocodes are used for the design of construction works, or parts thereof, the Nationally Determined Parameters of the Member State on whose territory the works are located shall be applied.. 24.

(27) Chapter 1: Basic requirements. Note: Any reference to an EN Eurocode design should include the information on which set of Nationally Determined Parameters was used, whether or not the Nationally Determined Parameters that were used correspond to the recommendations given in the EN Eurocodes (see 2.1.3). 2.1.6 National Provisions should avoid replacing any EN Eurocode provisions, e.g. Application Rules, by national rules (codes, standards, regulatory provisions, etc.). When, however, National Provisions do provide that the designer may – even after the end of the coexistence period - deviate from or not apply the EN Eurocodes or certain provisions thereof (e.g. Application Rules), then the design will not be called "a design according to EN Eurocodes". 2.1.7 When Eurocode Parts are published as European standards, they will become part of the application of the Public Procurement Directive. In all cases, technical specifications shall be formulated in public tender enquiries and public contracts by referring to EN Eurocodes, in combination with the Nationally Determined Parameters applicable to the works concerned, apart from the exceptions expressed in article 10.3 (Directive 93/37, article 10.2). However, in application of the PPD, and following the spirit of the New Approach, the reference to EN Eurocodes is not necessarily the only possible reference allowed in a Public contract. The PPD foresees the possibility for the procuring entity to accept other proposals, if their equivalence to the EN Eurocodes can be demonstrated by the contractor. Consequently, the design of works proposed in response to a Public tender can be prepared according to: EN Eurocodes (including NDPs), which give a presumption of conformity with all legal European requirements concerning mechanical resistance and stability, fire resistance and durability, in compliance with the technical specifications required in the contract for the works concerned; Other provisions expressing the required technical specification in terms of performance. In this case, the technical specification should be detailed enough to allow tenders to know the conditions on which the offer can be made and the owner to choose the preferred offer. This applies, in particular, to the use of national codes, as long as Member States maintain their use in parallel with EN Eurocodes (e.g. a Design Code provided by National Provisions), if also specified to be acceptable as an alternative to an EN Eurocode Part by the Public tender. 2.2 Indications to writers of EN Eurocodes 2.3 National Annexes of the EN Eurocode Parts 2.3.1 When a Eurocode Part is circulated by CEN for publication as an EN, the final text of the approved EN, according to CEN rules, is made available by CEN Management Centre to CEN members (the NSBs) in the 3 official languages (English, French and German).[This step corresponds to the DAV – Date of Availability] Each NSB shall implement this EN as a national standard by publication of an equivalent text (i.e. a version translated into another language) or by endorsement of one of the 3 language versions provided by CEN Management Centre (by attaching an "endorsement sheet"), within the timescale agreed for publication. The National standard transposing the EN Eurocode Part, when published by a National Standards Body (NSB), will be composed of the EN Eurocode text (which may be preceded by a National title page and by a National Foreword), generally followed by a National Annex. 25.

(28) Chapter 1: Basic requirements. 2.3.2 The National Standards Bodies should normally publish a National Annex, on behalf of and with the agreement of the national competent authorities. A National Annex is not necessary if an EN Eurocode Part contains no choice open for Nationally Determined Parameters, or if an EN Eurocode Part is not relevant for the Member State (e.g. seismic design for some countries). Note: As stated by the CEN Rules, the National Annex is not a CEN requirement (a NSB can publish an EN Eurocode Part without one). However, in the context of this Guidance Paper, the National Annex serves for NSBs to publish the Nationally Determined Parameters, which will be essential for design. 2.3.3 The National Annex may contain [See EN 1990 and EN 1991 Part 1-1 – Foreword – National standards implementing Eurocodes], directly or by reference to specific provisions, information on those parameters which are left open in the Eurocodes for national choice, the 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 EN Eurocode, values to be used where a symbol only is given in the EN Eurocode, country specific data (geographical, climatic, etc.), e.g. a snow map, the procedure to be used where alternative procedures are given in the EN Eurocode. It may also contain the following: decisions on the application of informative annexes, and, reference to non-contradictory complementary information to assist the user in applying the Eurocode. 2.3.4 A National Annex cannot change or modify the content of the EN Eurocode text in any way other than where it indicates that national choices may be made by means of Nationally Determined Parameters. 2.3.5 The National Annex of an EN Eurocode Part will normally be finalised when the safety and economy levels have been considered, i.e. at the end of the period allocated for the establishment of the Nationally Determined Parameters (see Annex A). 2.3.6 If a Member State does not choose any NDPs, the choice of the relevant values (e.g. the recommended value), classes or alternative method will be the responsibility of the designer, taking into account the conditions of the project and the National provisions. 2.3.7 The National Annex has an informative status. The content of a National Annex can be the basis for a national standard, via the NSB, and/or can be referred to in a National Regulation. 2.3.8 The National Annex can be amended, if necessary, according to CEN rules. 2.4 Packages of EN Eurocode Parts 2.4.1 The purpose of defining Packages, by grouping Parts of EN Eurocode, is to enable a common date of withdrawal (DoW) [At the date of withdrawal related to a new standard, all the specifications existing previously in the National collection of standards conflicting with the new standard have to be withdrawn and the national provisions have to be adapted to allow the legitimate use of EN Eurocodes] for all of the relevant parts that are needed for a particular design. Thus conflicting national standards shall have been withdrawn at the end of the coexistence period, after all of the EN Eurocodes of a Package are available, and National. 26.

(29) Chapter 1: Basic requirements. Provisions will have been adapted by the end of the National Calibration period, as described in Annex A. Publication of the individual Parts in a Package is likely to occur over a long period of time, so that, for many Parts, the coexistence period will be much longer than the minimum given in 2.5.5. When a National standard has a wider scope than the conflicting Eurocode Package, only that part of the National standard whose scope is covered by the Package has to be withdrawn. When more than one Package of EN Eurocodes is likely to be needed for the design of works, the dates of withdrawal of the related Packages can be synchronised. 2.4.2 No Parts from EN 1990 or the EN 1991, EN 1997 or EN 1998 series form a Package in themselves; those Parts are placed in each of the Packages, as they are material independent. 2.4.3 The list of the EN Eurocode Parts contained in the various Packages for each of the main materials, i.e. concrete, steel, composite concrete and steel, timber, masonry and aluminium, and their respective target dates, will be updated and made available through the CEN/MC web-site (see Annex C which presents the Packages as they are currently foreseen) 2.5 Arrangements for the implementation of EN Eurocodes and period of co-existence with national rules for the structural design of works 2.5.1 The arrangements for the implementation of an EN Eurocode Part include, from the time the final draft of the EN Eurocode is produced by the CEN/TC250, five periods: - Two periods before the date of availability (DAV): Examination period, CEN process period. - Three periods after the date of availability: Translation period, National calibration period, Coexistence period. The detailed content of each of the five periods is given in the table and chart in Annex A. The progress of each EN Eurocode (or Package), within these periods, will be provided by CEN/MC on their web-site. 2.5.2 The following basic requirements need to be fulfilled by the EN Eurocode Parts in order to be referred to in the national provisions: - Calculations executed on the basis of the Eurocode Part, in combination with the Nationally Determined Parameters, shall provide an acceptable level of safety. - The use of the EN Eurocode Part, in combination with the Nationally Determined Parameters, does not lead to structures that cost significantly more, over their working life [see Interpretative Document 1, clause 1.3.5], than those designed according to National standards or provisions, unless changes in safety have been made and agreed. 2.5.3 The European Commission encourages Member States to implement EN Eurocodes in the framework of their National Provisions. During the coexistence period, the construction regulation authorities should accept the use of EN Eurocodes, as an alternative to the previous rules (e.g. National codes, standards or other technical rules included, or referred to, in national provisions) for the design of construction works. Member States are also encouraged to adapt their national provisions to withdraw conflicting national rules before the end of the co-existence period. 2.5.4 When an EN Eurocode Part is made available, the Member States should: - set officially, before the end of the National calibration period (see Annex A), the Nationally Determined Parameters to be applied on their territory. In the event of any unexpected 27.

(30) Chapter 1: Basic requirements. obstacles to carrying out the calibration of an EN Eurocode Part, the Member State shall inform the Commission, when an extension of the period could be agreed by the SCC. - adapt, as far as necessary, their National Provisions so that the EN Eurocode Part can be used on their territory: - as a means to prove compliance of construction works with the national requirements for "mechanical resistance and stability" and "resistance to fire", in the sense of Annex I of the CPD, and - as a basis for specifying contracts for the execution of public construction works and related engineering services. If no NDPs are to be produced for an EN Eurocode Part, the coexistence period begins at DAV and ends at DoW. Thus the EN Eurocode is available and any existing national standard is still available, so that both can be used during this period. At the end of the "coexistence period" of the last EN Eurocode Part of a Package, the Member States should have adapted all their National Provisions which lay down (or refer to) design rules within the scope of the relevant Package. 2.5.5 Owing to the need for operational Packages (as defined in 2.4), the reference to the coexistence period of a Package is defined as the coexistence period of the last Eurocode Part of that Package. In Member States intending to implement EN Eurocodes, the coexistence period of this last part should be three years. After the three years coexistence period of the last EN Eurocode Part of a Package, the whole Package-related former conflicting national standards will be withdrawn, i.e. 5 years maximum after DAV [It is intended that the end of the coexistence period for each Package will be laid down by the Commission after consultation of Member States]. Conflicting National Provisions that would not allow the use of the first parts of a Package should be arranged, in order to allow the legitimate use of those Parts. 2.5.6 In order to increase the overall transparency of the implementation of the EN Eurocodes, the Commission wishes to be informed, by the Member States, of the main phases: translation, national calibration and coexistence Period, for each EN Eurocode Part, and the adaptation of National Provisions. Note: the Commission intends to prepare, for this purpose, a "test reporting form" on the basis of the items mentioned in the Annex B. A.4.3. Eurocodes Part 3: Use of EN Eurocodes in technical specifications for structural products This part of the Guidance Paper deals with structural products specified in the CPD as construction products: 3.1 Distinction is made between specifications for materials to be determined by test and specifications for components to be determined by calculation. 3.1.1 It follows from the CPD [Article 2.1 and 3.3] and the Interpretative Documents that there is a need for consistency between the technical specifications for construction products (hEN and ETA) and the technical rules for works. 3.1.2 For construction products, which contribute to the mechanical resistance and stability and/or fire resistance of works, two types of properties are distinguished, according to the validation method: Properties to be determined by testing (generally in the case of structural materials and constituent products, such as concrete, reinforcing steel for concrete, fire protection material, etc.), and Properties to be determined by calculation following methods, which are also used for the structural design of works (generally for prefabricated structural components and kits,. 28.

(31) Chapter 1: Basic requirements. consisting of structural components, such as prefabricated concrete components, prefabricated stairs, timber frame buildings kits, etc.). For both types of product properties the resulting values are to be "declared" in the information accompanying the CE marking [by application of CPD and in conformity with the mandate given by the Commission] of the product and used in the structural design of works or parts thereof. 3.1.3 For the reference to, or use of, EN Eurocodes in harmonised product specifications a distinction is made in this Part 3 between: - structural materials and constituent products with properties to be determined by testing, and - prefabricated structural components and kits consisting of structural components with properties to be calculated according to EN Eurocode methods. A.4.4. Eurocodes Part 4: Future actions related to the Eurocode Programme 4.1 Education 4.1.1 To build on the strong pedigree of the EN Eurocodes described above, the Commission recognises the importance of building on this with programmes of education to help the professions to implement the EN Eurocodes. 4.1.2 Aspects of education that need to be covered, include: informing and making the profession as a whole aware of the EN Eurocodes • providing continuing professional development and training to the profession • encouraging the production of handbooks, design aids, software etc. to facilitate the implementation of the EN Eurocodes • encouraging Universities and Technical Colleges to base their teaching of civil and structural engineering design on the EN Eurocodes. 4.1.3 The Commission, in liaison with industry and Member States, will encourage: • publication of easily understandable "jargon free" booklets covering the EN Eurocodes; • holding of European seminars aimed at the profession as a whole as key EN Eurocodes become available as ENs (e.g. EN 1990:Basis of Design); • publication of documents on the adoption of the EN Eurocodes through Government or on behalf of Government; • holding of meetings organised by professional and industry bodies to inform construction professionals and university teachers, to listen to and discuss their concerns, and to promote the opportunities offered by the EN Eurocodes; • the arrangement of continuing professional development and training courses; • the development of aids to implementation. 4.1.4 Central to any initiatives taken on education is the production of : • handbooks, worked examples and background documents; • software; • guides for everyday structures (e.g. normal buildings) based on the EN Eurocodes. Publishing companies, software houses and trade organisations will carry out these important activities, mainly as commercial ventures. Encouragement to these bodies can be given by a strong commitment to implementation of the EN Eurocodes both by the EC and the Member States. 4.1.5 Member States should encourage the use of the EN Eurocodes in private contracts, particularly through education and information campaigns, regardless of what may be requested by National provisions.. 29.

(32) Chapter 1: Basic requirements. 4.2. Research with regard to EN Eurocodes 4.2.1 The Commission services recognises that, for the Construction sector to remain competitive in the world construction industry, it is essential that the EN Eurocodes, once published, should remain the most up to date, useable International Codes of Practice, meeting the requirements for a profession practising in a competitive environment. 4.2.2 The EN Eurocodes should be further developed taking into account the innovative pressures of the market and the progress of scientific knowledge. 4.2.3 The pressures from the market are generated by: • new material and new products; • new ways for procurement and execution of works; • needs for economy whilst maintaining acceptable levels of safety. The progress of the scientific knowledge and methods are generated by: • the need to avoid disasters in the area of safety (e.g. seismic, fire); • a knowledge of phenomena acquired in other domains (e.g. aeronautics for wind action); • the answer to new economic or social needs (e.g. High Speed Railways, nuclear plants); • the availability of powerful and widely-distributed tools for calculation (computers and software). 4.2.4 Initiatives for research arise from • the industry or the users concerned; • public authorities in charge of safety, economy, scientific development and education (for example, the development of NDPs) • universities and research organisations experienced from their involvement as third parties. 4.2.5 In many cases there will be a mutual interest for both industry and public authorities (including the European Commission) in research and this should be reflected by agreements on common funding according to the following criteria: • Industrial and user's sources - the main funding for research whose objectives are short-term benefits or particular advantages for special innovative companies and associated industries and users (e.g. unique verifications and ETA's). • EC or National public funding - the main funding for research whose objectives are medium to long term benefits for the European construction industry (e.g. for improving technical specifications and design codes, harmonising models for actions and resistances, improving safety aspects). 4.3. Maintenance of EN Eurocodes 4.3.1 The maintenance of the EN Eurocodes is essential; the need for updating, revision and completion is strongly recognised so that an improved second generation of EN Eurocodes can evolve. However, a period of stability should be observed before embarking on changes other than to correct errors. 4.3.2 Maintenance work will involve: • reducing open choices (NDPs); • urgent matters of health and safety; • correcting errors;. 30.

(33) Chapter 1: Basic requirements • • •. ensuring the most up to date information is in the EN Eurocodes, recognising recent proven innovations and improvements in construction technology; feedback from use of the EN Eurocodes in the various Member States through CEN; requests from industrial organisations or public authorities to CEN members for revision.. 4.3.3 The organisation of maintenance should start after the receipt of a positive vote on a draft EN Eurocode, a Maintenance Group should be formed by the relevant CEN/TC250 SC to: • give further consideration of co-ordination items arising from the work of other Project Teams (this is necessary as the various parts of the EN Eurocodes are not being prepared simultaneously); • provide explanations to questions arising from the use of the EN Eurocode, e.g. on background and interpretation of rules; • collect comments and requests for amendment; • prepare action plans for urgent revision in the case of safety related matters, or future systematic revisions according to the CEN procedure and as decided by CEN/TC250. 4.3.4 The strategy to provide adequate resources to support the maintenance of the EN Eurocodes should be decided by the European Commission, Member States, Industry and CEN seeking to find a balance between: • the requirements for public safety; • the competitive demands of industry; • the availability of funds.. 31.

(34) Chapter 2: Basis of design – general principles. CHAPTER 2: BASIS OF DESIGN – GENERAL PRINCIPLES Milan Holický1, Jana Marková1 1. Klokner Institute, Czech Technical University in Prague, Czech Republic. Summary Construction works are complicated technical systems suffering from a number of significant uncertainties in all stages of execution and use. Reliability is therefore an important aspect of their design. The most important historical methods include method of permissible stresses and method of global and partial factors. Present European standard EN 1990 Eurocode - Basis of structural is based on the concept of limit states in conjunction with partial factor method. Probabilistic approach and methods of risk assessment are used as scientific bases of the partial factor method and as an alternative design method.. 1. INTRODUCTION. 1.1. Background documents. The standard EN 1990 Basis of structural design [1] and EN 1991-1-1 Actions on structures [2] are the fundamental documents for the whole system of Eurocodes. These documents are available since April 2002 and at present are implemented into the systems of national standards. An important background document is the International Standard ISO 2394 [3], Probabilistic Model Code [5], Designer's Guide to EN 1990 [5] and other literature (for example [6]). 1.2. General principles. Two basic sets of limit states should be considered in accordance to the design principles of EN 1990 [1]. Particularly it should be verified that the load effect E does not exceed the resistance of the structure in ultimate limit states and the relevant criteria for serviceability limit states. In common cases the general condition of structural performance with respect to ultimate or serviceability limit states may be expressed by the following inequality E < R,. (1). Here R denotes the resistance. Note that in EN 1990 [1] the design value Ed and Rd are used in the condition (1) to represent the load effect E and resistance R. When probabilistic design is used, then the load effect E and resistance R are considered as random variables and probability that the condition (1) is valid or violated is analysed. For the selected design situations and identified limit states, the critical load cases should be determined. In accordance with EN 1990 [1], a load case is a compatible load arrangement, sets of deformations and imperfections considered simultaneously with fixed variable actions and permanent actions. Document [1] is primarily based on the partial factor method, called also semi-probabilistic method. However, as an alternative, a design directly based on probabilistic methods is also allowed.. 32.

No results found