AD 335: Eurocode design and National Annexes

As design to the Eurocodes commences, this Advisory Desk note reminds designers how important it is to refer to the appropriate National Annexes. The appropriate National Annex is that for the country where the structure is to be constructed – not the country where the design takes place. Serious errors can be made if the correct National Annex is not consulted.

Each Eurocode Part is implemented, in each country, by a national standard – for example EN 1990 is implemented in the UK as BS EN 1990. Within the text of the Eurocode Parts, there are specific provisions for national choice, where the National Annex may give alternative procedures, values and recommendations.  Perhaps the best known examples of this allowance for national choice are the values of the partial factors on actions and material strengths – γ_G, γ_Q, γ_M etc. – but designers should be aware that a whole range of other choices are made in the National Annexes.

A National Annex may be attached to the body of the national standard that implements the Eurocode Part but it is a CEN requirement that the National Annexes are also available (sold) separately. In the UK, the UK National Annexes are at present available from BSI only as separate documents. In the other CEN member countries the National Annexes will be available in their own language, although it is expected that English language versions will be made available in many cases. Copies of non-UK National Annexes may be obtained from BSI (on their Eurocodes website it advises that “For information and to purchase National Annexes applicable outside the UK contact BSI Distributor sales on 020 8996 7511 or email Distributor.Sales@bsigroup.com.”) or alternatively the relevant national standards body may be contacted directly.

Most of the key UK National Annexes have now been published.

The references to the National Annex in the Eurocode text are easy to miss – it is recommended that designers read each relevant National Annex carefully and note where the core recommendations have been modified, possibly by highlighting their copy of the Eurocode text.

The following list, which is by no means exhaustive, offers a selection of examples where significant changes are made in the UK National Annex.

It should be noted that some countries largely adopt the recommended values whilst others make extensive changes. The importance of careful reference cannot be overstated!

Contact: D G Brown
Tel: 01344 636525
Email: advisory@steel-sci.com