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Eurocodes: Building the future

Further harmonisation of the EN Eurocodes

The EN Eurocodes are the result of a long procedure of bringing together and harmonising the different design traditions in the Member States.

Member States should use the recommended values provided by the Eurocodes when nationally determined parameters have been identified in the Eurocodes. They should diverge from those recommended values only where geographical, geological or climatic conditions or specific levels of protection make that necessary.
Member States should, acting in coordination under the direction of the Commission, compare the nationally determined parameters implemented by each Member State and assess their impact as regards the technical differences for works or parts of works. Member States should, at the request of the Commission, change their nationally determined parameters in order to reduce divergence from the recommended values provided by the Eurocodes.

Commission Recommendation 2003/887/EC

Flexibility and harmonisation

The EN Eurocodes are the result of a long procedure of bringing together and harmonising the different design traditions in the Member States. In the same time, the Member States keep exclusive competence and responsibility for the levels of safety of works. The differences in the environmental conditions and in the ways of life in the Member States also require flexibility in the National Application of the EN Eurocodes.

Therefore the EN Eurocodes include Nationally Determined Parameters (NDPs) which

  • take into account differences in geographical, geological or climatic conditions;
  • result from different design cultures and procedures for structural analysis;
  • arise from the requirement for safety levels in the relevant Member States.

Member States are encouraged to minimize the number of cases where recommendations for a value or method are not adopted for their NDPs. The principal objectives of further harmonisation are as follows

  • the reduction of NDPs in the EN Eurocodes resulting from different design cultures and procedures in structural analysis;
  • the reduction of NDPs and their variety through the strict use of recommended values;
  • the gradual alignment of safety levels across Member States.

It is important to harmonise not only the values of the NDPs (harmonisation across national borders), but also the methodologies used for their assessment, as well as the design procedures used for different structures (harmonisation across different materials), e.g. reinforced concrete, steel and composite structures.

Further harmonisation of the EN Eurocodes will be achieved through collaboration within CEN/TC250, National Authorities, International Technical Scientific Organisations, Industry and the Commission/JRC.

In the mandates M/466 and M/515 for amending the existing Eurocodes and extending the scope of structural Eurocodes, the European Commission requested CEN to assess all existing Eurocodes concerning the potential to significantly reduce the number of Nationally Determined Parameters. This work should be done in close collaboration with the JRC and be based on the NDPs as defined on National level and uploaded in the specific NDP database.

Harmonisation benefits

By choosing the same values and methods, the Member States will boost the free circulation of products and services, while guaranteeing a high level of safety in construction works. In particular, the benefits of using the Eurocodes comprise

  • exchange of design and construction services;
  • marketing and use of structural components and kits;
  • marketing and use of materials and constituent products;
  • preparation of common design aids and software;
  • increase the competitiveness of the European construction industry.

Harmonisation of NDPs

In all 59 parts of the Eurocodes there are 1 573 Nationally Determined Parameters (NDPs). In a number of cases, an NDP cannot be represented by a single numerical value. In fact, many NDPs take the form of tables, graphs, acceptance of the recommended procedure, choice of calculation approach among given alternatives, introduction of a new procedure, etc.

Types of NDPs
TypeType DescriptionNumber%
1Values of parameters39726.3
2Reference to some set of values – tables16911.2
3Acceptance of the recommended procedure, choice of calculation approach, when alternatives are given, or introduction of a new procedure50233.3
4Country specific data181.2
5National charts or tables10.1
6Diagrams151.0
7References to non-contradictory complementary information231.5
8Decision on the application of informative Annexes24916.5
9Provision of further, more detailed information1026.8
10Reference to information included in an informative annex302.0

 

Among the material Eurocodes, EN 1992: Design of concrete structures and EN 1993: Design of steel structures include the highest amount of NDPs. The objective of further harmonisation for these NDPs, e.g. partial factors for material and product properties, is the adoption of the recommended values.

EN 1991: Actions on structures contains a big number of NDPs, most of them arising from different geographical, geological and climatic conditions. Further harmonisation will be sought with regard to the methodologies used for the assessment of these NDPS.

The database of NDPs is managed by the Safety and Security of Buildings Unit of the DG Joint Research Centre of the European Commission.

Number and percentage of NDPs per NDP type
Number and percentage of NDPs per NDP type

 

Number and percentage of NDPs per EN Eurocode
Number and percentage of NDPs per EN Eurocode

 

By 17 January 2022, the acceptance average of the recommended values (RVs) was 73%. The analysis was based on 72% of the NDPs with RVs that are expected to be uploaded in the Database.

Acceptance of recommended values per EN Eurocode
Acceptance of recommended values per EN Eurocode by 17 January 2022

 

Acceptance of recommended values per country by 17 January 2022