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Further Harmonization > Harmonization of NDPs

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Further Harmonization
- Harmonization of NDPs

Harmonization 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
Type	Type Description	Number	%
1	Values of parameters	397	26.3
2	Reference to some set of values – tables	169	11.2
3	Acceptance of the recommended procedure, choice of calculation approach, when alternatives are given, or introduction of a new procedure	502	33.3
4	Country specific data	18	1.2
5	National charts or tables	1	0.1
6	Diagrams	15	1.0
7	References to non-contradictory complementary information	23	1.5
8	Decision on the application of informative Annexes	249	16.5
9	Provision of further, more detailed information	102	6.8
10	Reference to information included in an informative annex	30	2.0

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

Distribution of NDPs in the EN Eurocodes

Number and percentage of NDPs per EN Eurocode

By 7 October 2019, the acceptance average of the recommended values (RVs) was 74%. The analysis was based on 69% of the NDPs with RVs that are expected to be uploaded in the Database.

Acceptance of recommended values per EN Eurocode

NDPs database: Acceptance Percentage Map of recommended values per country as by 20191007

Acceptance of recommended values per country

Background documents

Background documents are of interest to Member States in the procedure of choosing their NDPs, as well as to Technical Assessment Bodies concerned with ETAs. For the general user and industry, they will give explanations of the origin of technical rules.

Background documents are useful in order to

explain the origin of technical rules;
justify the provisions where practical experience is insufficient;
justify the recommended values of NDPs;
support Member States when choosing the NDPs;
give guidance to users;
provide information for ETAs.

In the long term, background documents will provide information on the origin of existing rules when these rules shall be further developed.