The Structural Eurocodes are a set of harmonised structural design codes for building and civil engineering works. The first generation of the Structural Eurocodes were viewed as the most comprehensive and advanced suite of structural design standards in the world when published more than 10 years ago, writes Dr Ken Murphy.

In that time, their impact has been considerable. It is estimated that the design standards are being used by up to 500,000 professional engineers across Europe and the wider world.

The Eurocodes are now widely accepted as the basis for harmonised structural design throughout Europe, allowing engineers to trade and tender for projects across the continent.

The Eurocodes are used in combination with a suite of execution, material, product and testing Euronorms also known as EN standards. The combined suite of standards (Eurocodes plus ENs) cover all aspects of construction, specifically design rules, material properties, execution of structures and special works, specifications for construction products, as well as quality control.

The Eurocodes were adopted in Ireland in March 2010 under the designations I.S. EN 1990 to I.S. EN 1999 and were referenced in Technical Guidance Document A (TGD A) (Structure) to Part A of the Irish building regulations in 2012.

At present there are 58 parts within the Eurocode suite of standards. However, changes to the Eurocodes are on the way.

What is happening to the Structural Eurocodes?

The development of the second generation Eurocodes was mandated by the European Commission in December 2012. It has become one of the largest standardisation projects funded by the commission and EFTA with total funding provided to complete the work standing at €11.8 million.

This ambitious project to revise the Eurocodes is being overseen by the European Committee for Standardization (CEN) technical committee, CEN/TC 250 – Structural Eurocodes.

The work is being led by the British Standards Institution (BSI) which holds the secretariat of the technical committee on behalf of CEN and represents the UK's commitment to the Eurocodes project.

The main goals of the second generation Eurocodes will be to:

1. Enhance their ease of use, providing clarity for the user;
2. Incorporate new design, performance and robustness requirements;
3. Reduce the number of nationally determined parameters (NDPs); and,
4. Develop a number of new Eurocodes parts to provide guidance on the following;

• Assessment and retrofitting of existing structures;
• Structural glass; and,
• Actions on structures due to atmospheric icing and waves and currents.

As a result of this work the number of Eurocode parts will increase from 58 to 64.

The initial work in revising the Eurocodes is nearing an end with the next stage in their development approaching. The second stage involved in the revision will see the draft Eurocode parts being made available to all members of the public across Europe to review and comment upon.

This stage is known as 'Enquiry'. Due to the number of Eurocode parts being developed the Enquiry stage for the draft parts will be launched in biannual blocks, with a number of related parts in each block.

The public will be given three months to review and submit comments on the parts in each block, after which, each member state will vote on whether the draft is appropriate to be published as a Eurocode standard part, subject to the comments received.

How will this impact me?

Although the Structural Eurocodes have been in place for more than a decade, it is likely that the second generation Eurocodes will have an impact on the construction sector in Ireland, from procurement, initial design phase, through to the execution and completion of civil and structural engineering works.

All stakeholders involved in construction projects (i.e. procurement bodies, regulators, designers, engineers and clients/owners) will need to consider how any changes to the Eurocodes might affect them.

For example, ensuring structures are sufficiently robust to withstand changes due to climate change while fulfilling their design life is being examined as part of the revision of the Eurocodes, and these will be areas that the construction sector will need to consider in the future, if not already.

One change which may have an impact on structural designers is the increased prominence given to geotechnical design within Eurocode 0 as evidenced by the change in the title of EN 1990 from 'Basis of structural design' to 'Basis of structural and geotechnical design' as well as the inclusion of geotechnical design within the scope of EN 1990.

This may require structural designers to consider geotechnical requirements in more detail when designing structures which heretofore may not have been the case. 

What is currently happening?

The 'Enquiry' stage of the draft second generation Eurocode parts has started. prEN 1996-1-1 - Eurocode 6: Design of masonry structures - Part 1-1: General rules for reinforced and unreinforced masonry structures was the first draft made available in Q4 2019 via national standards bodies such as the National Standards Authority of Ireland (NSAI), thus affording the general public across Europe the opportunity to review and comment on how structures built from masonry units (concrete blocks and bricks) would need to be designed in Europe and Ireland in the future.

On September 3, 2020, a significant milestone was reached, with the launch of the prEN 1990 – Basis of structural and geotechnical design 'Enquiry'.

As this is the cornerstone on which the Eurocodes are founded, it is a key document that all stakeholders in the construction sector should be aware of and take the opportunity to review and comment on. There are several changes being proposed to EN 1990 which it is hoped will make the Eurocodes easier to use.

These include:

• A simplified presentation of what is needed for 'everyday use' by a practising engineer;
• Increased focus on geotechnical and fatigue requirements;
• Introduction of new concepts such as management measures to achieve structural reliability; and,
• Affording countries more control on the application of the informative annexes which will accompany EN 1990.

September 2020 also saw the launch of the prEN 1993-1-1 - Eurocode 3: Design of steel structures – Part 1-1 General rules and rules for buildings 'Enquiry'.

This draft part aims to set out the requirements to be met when designing steel structures in the future and changes to it and the other Eurocode 3 parts include:

• Incorporation of high strength steel grades up to S960 into EN 1993-1-1;
• Increased integration of the execution standards EN 1090-1 and EN 1090-2 with the requirements of EN 1993;
• Additional guidance on fatigue, FEM and large holes in beams; and
• Examining how to incorporate the reuse of steel in support of the circular economy.

These 'Enquiry' drafts will be followed in 2021 by the main parts to Eurocode 1 – Actions on structures and Eurocode 2 – Design of concrete structures.

Designers of concrete structures will need to be aware of the potential changes which are likely to occur within Eurocode 2, in particular, changes in the rules governing the durability of concrete.

These Eurocode parts (EN 1990, EN 1991-1-1, EN 1992,1-1, EN 1993-1-1 and EN 1996-1-1) represent some of the principal Eurocode parts which are used in Ireland. 'Enquiry' drafts for Eurocode 7 for geotechnical design (EN 1997) and Eurocode 5 on timber design (EN 1995) are expected in 2022 and 2023 respectively.

The draft Eurocode parts will be available to the Irish public to review, comment on and download via the NSAI's website Your Standards Your Say when the Enquiry stage for the respective draft begins.

What can I do?

Supported by the NSAI and Department of Housing, Local Government and Heritage, (DHLGH) Irish experts have been actively engaged in the CEN/TC 250 work programme to date, closely monitoring the revisions to the Eurocode standards, while a number of Irish experts have been involved in drafting the second generation codes.

However, the time has now come for the Irish construction sector to take the opportunity to review and have its say on the content of the draft revised Eurocode parts as they are being developed and finalised. This can be done by reviewing and commenting on the drafts via the NSAI's website Your Standards Your Say when the Enquiry drafts are made available.

It can also be done by getting involved and engaging with the NSAI's technical committee on the Structural Eurocodes – NSAI/TC 15. The benefits of getting involved include:

1. Gaining early access to information that will shape the direction of the construction sector over the next five to 10 years;
2. Giving you, your organisation or association a voice in the development of the standards both at national and international level;
3. Providing you, your organisation or association with an opportunity to raise any needs or concerns in relation to the codes which may well affect you or your business in the future;
4. Increased opportunities for networking in the industry at national and international level; and,
5. The work on standards is recognised by many professional institutions as a way of demonstrating continued professional development.

There is also an opportunity to influence and contribute to the revision of the associated Irish National Annexes (NAs) and national non-conflicting guidance documents developed by the NSAI that will accompany the revised Eurocodes.

What are National Annexes?

The levels of safety required for buildings and engineering structures designed in accordance with the Structural Eurocodes is controlled at a national level.

The control of these levels of safety as well as climatic conditions and procedures are addressed in the Structural Eurocodes through a mechanism known as a Nationally Determined Parameter (NDP), which allows countries make their own choices and set their own requirements.

These NDPs are set out in the accompanying National Annex (NA) to each Eurocode part and these documents are maintained and revised in Ireland by the NSAI.

As well as the Eurocode parts, the National Annexes which accompany them are referred to in the Technical Guidance Documents to the Irish Building Regulations, in particular TGD A (2012) in which it states that "any reference to Eurocodes must be taken to include the relevant Irish National Annex".

The National Annexes also provide information on where to find additional guidance on how the design rules within the Eurocodes can be applied in Ireland.

Through participation in the NSAI's technical committee on the Structural Eurocodes (NSAI/TC 15) all construction sector stakeholders have an opportunity to advise the NSAI on the appropriate NDP values required for a specific Eurocode part and what additional guidance or reference material the NAs should contain or refer to. This is also done through liaisons with other NSAI technical committees involved in construction such as:

• NSAI/TC 3 - Concrete Standards Consultative Committee
• NSAI/TC 8 – Timber
• NSAI/TC 16 – Fire Safety

What other Eurocode guidance does the NSAI publish?

Along with the development of National Annexes to the Eurocodes, NSAI/TC 15 members can influence the development of national Non-Contradictory Complementary Information (NCCI) guidance documents which are maintained and published by the NSAI. These NCCI documents include:

• S.R. 325 - Recommendations for the design of masonry structures in Ireland to Eurocode 6, provides guidance on the design of masonry structures and on the use of masonry units (i.e. concrete blocks), mortar, ancillary components. It also establishes the minimum performance levels of such construction products in Ireland;
• S.R. 70 – Timber in construction – Eurocode 5 – Trussed rafters, sets out the requirements for the fabrication and use of timber trussed rafters; as well as guidance on design, structural analysis, bracing and site work for both trusses and roofs; and
• S.R. 71 - Timber in construction – Eurocode 5 – Span tables and guidelines which gives the maximum spans for a range of solid softwood structural members in buildings, such as floor and ceiling joists, rafters and roof purlins.

If you wish to participate in the standardisation process and contribute to the development of the second Generation Eurocodes, their accompanying Irish NAs or associated NCCI documents please visit the NSAI site to register your interest. 

Author: Dr Ken Murphy is a materials science graduate from the University of Limerick and spent 12 years working in the area of pipeline asset management in the oil, gas and water industries globally. He joined the NSAI in 2017 as a standards officer and is primarily responsible for managing the second generation Eurocode work programme for the NSAI's Structural Eurocodes committee as well as the work programmes of the concrete, cranes and wastewater committees within the NSAI.