EN 1993-1-13:2024/prA1

• Abstract:

  1.1 Scope of EN 1993-1-13; 1.1.1 General; (1) This document gives supplementary provisions that extend the application of EN 1993-1-1 and EN 1993-1-5 to the design of rolled and welded steel sections with various shapes of web openings. The following cases are considered:; - rolled or welded beams with single or widely spaced web openings;; - rolled or welded beams with closely spaced web openings;; - cellular beams with circular openings made by cutting and re-welding two parts of steel sections that may be different in dimensions;; - beams with hexagonal and sinusoidal openings made by cutting and re-welding two parts of steel sections that may be different in dimensions.; (2) This document applies to uniform members with I or H profiles, which are symmetric about the weak axis. It does not apply to non-prismatic or curved beams although the same principles can apply.; (3) This document applies to steel beams with web openings that are subjected to sagging (positive) or to hogging (negative) bending moments.; (4) This document covers the verification of the resistance at the openings and their effects on the global behaviour of the beam, including lateral torsional buckling.; (5) Alternative methods are presented for beams with circular openings and with sinusoidal openings in which the forces and resistances are calculated by increments around or along the openings and which are suitable for computer methods.; (6) This document applies to web slenderness, hw/tw, not exceeding 121ε. The local checks at and between adjacent openings apply to web slenderness up to this limit. The material parameter ε is defined in EN 1993-1-1:2022, 5.2.5 (2).; NOTE The limit of 121ε is the limit of a Class 4 web for a steel section with equal flanges. It is used as a convenient limit for the application of this document, including mono-symmetric sections.; (7) This document does not cover fatigue. In case of fatigue, EN 1993-1-9 applies.; (8) This document does not cover fire design. For the design in case of fire, EN 1993-1-2 applies.; (9) This document does not cover the buckling verification of members with web openings under axial force.; 1.1.2 Shapes of web openings; (1) The different shapes of web openings that are considered in this document are shown in Figure 1.1.; Figure 1.1 - Different shapes of web openings in steel beams; 1.1.3 Stiffened openings; (1) This document also covers openings in the web of beams that are reinforced by longitudinal stiffeners and/or transverse stiffeners on one or both sides of the web, see Figure 1.2.; NOTE The National Annex can give rules for alternative types of stiffener.; Figure 1.2 - Stiffening of openings in beam webs; 1.2 Assumptions; (1) Unless specifically stated, EN 1990, the EN 1991 series and EN 1993-1-1 apply.; (2) The design methods given in EN 1993-1-13 are applicable if:; - the execution quality is as specified in EN 1090-2, and; - the construction materials and products used are as specified in the relevant parts of the EN 1993 series, or in the relevant material and product specifications.

• Status: Not Published
• Publication Date: 30-Sep-2027
• ICS: 91.010.30 - Technical aspects
• ICS: 91.080.13 - Steel structures
• Technical Committee: CEN/TC 250 - Structural Eurocodes
• Drafting Committee: CEN/TC 250/SC 3/WG 20 - EN 1993-1-13 - Beams with large web openings
• Current Stage: 4060 - Closure of enquiry - Enquiry
• Start Date: 20-Aug-2026
• Due Date: 30-Nov-2026
• Completion Date: 20-Aug-2026
• Ref Project: SIST EN 1993-1-13:2024/oprA1:2026 - Eurocode 3 - Design of steel structures - Part 1-13: Beams with large web openings

• Amends: EN 1993-1-13:2024 - Eurocode 3 - Design of steel structures - Part 1-13: Beams with large web openings
• Effective Date: 20-Jan-2026

EN 1993-1-13:2024/prA1 is a CEN draft amendment to Eurocode 3, Part 1-13. It updates the steel design rules for beams with large web openings, including beams with single, closely spaced, cellular, hexagonal and sinusoidal openings, and it refines the checks for web-post and end-post behaviour, stiffened openings, connection details and serviceability effects. The document is aimed at engineers and other professionals who design or verify steel beams with openings under bending and shear.

What does EN 1993-1-13:2024/prA1 specify?

EN 1993-1-13:2024/prA1 modifies EN 1993-1-13:2024, which gives supplementary provisions for the design of rolled and welded steel sections with web openings. The underlying standard extends EN 1993-1-1 and EN 1993-1-5 to beams with large openings in the web, and it is organized through clauses on scope, terms and definitions, basis of design, structural analysis, ultimate limit states and serviceability limit states.

The scope covers beams with I or H profiles that are symmetric about the weak axis, including members in sagging or hogging bending. It excludes non-prismatic or curved beams, fatigue design, fire design and axial-force buckling checks. Fastener holes are outside its scope.

Annex	What it covers
None identified in the amendment text

What are the key requirements of EN 1993-1-13:2024/prA1?

EN 1993-1-13:2024/prA1 mainly clarifies when the large-opening rules apply and refines how the resistance checks are carried out in practice. The amendment matters because it changes the way designers classify openings, choose buckling curves and verify local effects around openings.

• Clause 1.1.1 clarifies the opening types covered, including openings that are too large to fit within a specified envelope, eccentric openings close to the flange, and closely spaced openings. In practice, this helps a designer decide whether the special opening rules apply or whether EN 1993-1-1 is enough.
• Clause 1.1.3 confirms that openings may be stiffened by longitudinal and/or transverse stiffeners on one or both sides of the web. That means the standard can be used for reinforced openings, not only bare cut-outs.
• Clause 1.2 keeps the design methods tied to EN 1990, the EN 1991 series and EN 1993-1-1 unless stated otherwise, and to execution quality per EN 1090-2. In practice, the opening checks sit inside the wider Eurocode framework and depend on execution and product conformity.
• Clause 4.2 adds resistance to web buckling next to widely spaced openings. This is important because the web beside an opening can govern even when the opening itself seems acceptable.
• Clause 7 and Clause 8 update the analysis and ultimate limit state checks for openings, including Vierendeel bending, web-post buckling and end-post resistance. The practical effect is that designers must consider the local frame action created by the opening, not only the global beam action.
• Clause 8.6.3 and 8.7.6 improve the choice of buckling curves for web-post buckling. The amendment states which curve to use for rolled sections and which to use for welded sections, so the stability check is less open to interpretation.
• Clause 8.8.1 and 8.8.2 revise end-post and local-load checks, including connection detailing around notches and the condition for verifying a local load on a Tee section. This affects how loads are introduced into the beam and how the opening is detailed.
• Clause 9 updates serviceability rules, which matters because deflection around an opening feeds into the ultimate Vierendeel check.

What terms does EN 1993-1-13:2024/prA1 define?

• Large web opening - An opening in the web for which checking only the global shear and bending resistance of the net section is not enough, because local effects around the opening also have to be verified.
• Web-post - The strip of web material between adjacent openings or beside an opening, which has to resist shear and buckling effects.
• End-post - The web zone at the end of a beam with openings, where the remaining section must still carry forces safely.
• Vierendeel bending - The local bending action that develops around an opening and creates additional forces and deflection near the cut-out.
• Sagging bending moment - A positive bending moment in the beam under the sign convention used by the standard.
• Hogging bending moment - A negative bending moment in the beam under the sign convention used by the standard.
• Ultimate limit state (ULS) - The safety state used for resistance and collapse-type checks.
• Serviceability limit state (SLS) - The state used for deflection and usability checks.

Who uses EN 1993-1-13:2024/prA1?

EN 1993-1-13:2024/prA1 is used by structural engineers, steelwork designers, checking engineers and software developers who model beams with openings. It is also relevant to quality managers, fabricators and contractors working to EN 1090-2, because the opening rules depend on execution quality and on the selected materials and products. Typical applications are steel building frames and other steel structures where services or architectural requirements lead to large web openings.

What changed in EN 1993-1-13:2024/prA1 from the previous edition?

EN 1993-1-13:2024/prA1 is a draft amendment to EN 1993-1-13:2024. The amendment states these main changes:

• the definition of large web openings is clarified;
• the selection of buckling curves for web-post buckling is improved, using recent research;
• the end-post calculation method is improved, using recent research;
• technical and editorial corrections are made to improve clarity and usability.

Which standards are used with EN 1993-1-13:2024/prA1?

• EN 1990-1 - basis of structural and geotechnical design for new structures, used in updated references.
• EN 1990 - general basis of design, applied unless the document states otherwise.
• EN 1991 series - actions on structures that provide the loading cases used in design.
• EN 1993-1-1:2022 - general rules for steel structures, including the material parameter ε and several reference checks.
• EN 1993-1-2 - structural fire design, used when fire design is needed.
• EN 1993-1-5:2024 - plated structural elements, used for stiffener design and related checks.
• EN 1993-1-9 - fatigue, used for cases with cyclic loading.
• EN 1090-2 - execution of steel structures, used for the required execution quality.

What does the EN 1993-1-13:2024/prA1 document contain?

The document contains a European foreword and a set of amendments to clauses throughout the base standard. It revises the Introduction, Scope, Terms and definitions, Basis of design, Structural analysis, Ultimate limit states and Serviceability limit states.

It also updates formulas, table references and figure references in Clause 8, including the checks for web-post and end-post resistance, local loads on Tee sections, and stiffened openings. Several edits are technical, while others are editorial corrections to align the document with the rest of the Eurocode set.

SLOVENSKI STANDARD
01-julij-2026
Evrokod 3 - Projektiranje jeklenih konstrukcij - 1-13. del: Nosilci z velikimi
mrežnimi odprtinami
Eurocode 3 - Design of steel structures - Part 1-13: Beams with large web openings
Eurocode 3 - Bemessung und Konstruktion von Stahlbauten - Teil 1-13: Träger mit
großen Stegöffnungen
Eurocode 3 - Calcul des structures en acier - Partie 1-13 : Poutres avec grandes
ouvertures d'âme
Ta slovenski standard je istoveten z: EN 1993-1-13:2024/prA1
ICS:
91.010.30 Tehnični vidiki Technical aspects
91.080.13 Jeklene konstrukcije Steel structures
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
EN 1993-1-13:2024
NORME EUROPÉENNE
EUROPÄISCHE NORM
prA1
May 2026
ICS 91.010.30; 91.080.13
English Version
Eurocode 3 - Design of steel structures - Part 1-13: Beams
with large web openings
Eurocode 3 - Calcul des structures en acier - Partie 1- Eurocode 3 - Bemessung und Konstruktion von
13 : Poutres avec grandes ouvertures d'âme Stahlbauten - Teil 1-13: Träger mit großen
Stegöffnungen
This draft amendment is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 250.

This draft amendment A1, if approved, will modify the European Standard EN 1993-1-13:2024. If this draft becomes an
amendment, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for
inclusion of this amendment into the relevant national standard without any alteration.

This draft amendment was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 1993-1-13:2024/prA1:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Modifications throughout the whole document . 4
2 Modifications to the Introduction . 4
3 Modification to Clause 1, “Scope” . 5
4 Modifications to Clause 3, “Terms and definitions” . 5
5 Modifications to Clause 4, “Basis of design” . 5
6 Modification to Clause 7, “Structural Analysis” . 6
7 Modifications to Clause 8, “Ultimate Limit States” . 6
8 Modification to Clause 9, “Serviceability limit states” . 8
European foreword
This document (EN 1993-1-13:2024/prA1:2026) has been prepared by Technical Committee
CEN/TC 250 “Structural Eurocodes”, the secretariat of which is held by BSI. CEN/TC 250 is responsible
for all Structural Eurocodes and has been assigned responsibility for structural and geotechnical design
matters by CEN.
This document is currently submitted to the CEN Enquiry.
This document will amend EN 1993-1-13:2024.
NOTE Some modifications are purely editorial corrections to improve the quality of the document and these
will not be tagged in the consolidated publication, as noted after the modification.
The following main changes to EN 1993-1-13:2024 are included in the amendment:
— The definition of large web openings is clarified.
— The selection of the buckling curves for web-post buckling is improved, based on recent research
works and publications.
— The calculation method for end-post is improved, based on recent research works and publications.
— This amendment corrects technical and editorial points in EN 1993-1-13:2024 to increase the clarity
and user friendliness.
The first generation of EN Eurocodes was published between 2002 and 2007. This document forms part
of the second generation of the Eurocodes, which have been prepared under Mandate M/515 issued to
CEN by the European Commission and the European Free Trade Association.
The Eurocodes have been drafted to be used in conjunction with relevant execution, material, product
and test standards, and to identify requirements for execution, materials, products and testing that are
relied upon by the Eurocodes.
The Eurocodes recognize the responsibility of each Member State and have safeguarded their right to
determine values related to regulatory safety matters at national level through the use of National
Annexes.
1 Modifications throughout the whole document
Add “-1:2023+A1:2026” to the reference “EN 1990” in Clause 2 and update throughout the text when a
dated reference is given.
Add part number “-1” to the reference “EN 1990” and update throughout the text when an undated reference
is given.
2 Modifications to the Introduction
In 0.1, replace “— New parts are under development, e.g. Eurocode for design of structural glass”
with “— EN 19100 Eurocode 10 — Design of glass structures”.
In 0.1, add the following new list item: “— New parts are under development, e.g. Eurocode for design of
fibre-polymer composite structures and for design of tensioned membrane structures”.
In 0.2, replace in the first paragraph the reference to EN 1990 with “EN 1990-1 — Basis of structural and
geotechnical design — Part 1: New structures”.
In 0.2. replace the list of the various parts of EN 1993 with:
“EN 1993-1-1, Eurocode 3 — Design of Steel Structures — Part 1-1: General rules and rules for buildings;
EN 1993-1-2, Eurocode 3 — Design of Steel Structures — Part 1-2: Structural fire design;
EN 1993-1-3, Eurocode 3 — Design of Steel Structures — Part 1-3: Cold-formed members and sheeting;
NOTE Cold-formed hollow sections supplied according to EN 10219 (all parts) are covered in EN 1993-1-1.
EN 1993-1-4, Eurocode 3 — Design of Steel Structures — Part 1-4: Stainless steel structures;
EN 1993-1-5, Eurocode 3 — Design of Steel Structures — Part 1-5: Plated structural elements;
EN 1993-1-6, Eurocode 3 — Design of Steel Structures — Part 1-6: Strength and stability of shell structures;
EN 1993-1-7, Eurocode 3 — Design of Steel Structures — Part 1-7: Plate assemblies with elements under
transverse loads;
EN 1993-1-8, Eurocode 3 — Design of Steel Structures — Part 1-8: Joints;
EN 1993-1-9, Eurocode 3 — Design of Steel Structures — Part 1-9: Fatigue;
EN 1993-1-10, Eurocode 3 — Design of Steel Structures — Part 1-10: Material toughness and through-
thickness properties;
EN 1993-1-11, Eurocode 3 — Design of Steel Structures — Part 1-11: Tension components;
EN 1993-1-12, Eurocode 3 — Design of Steel Structures — Part 1-12: Additional rules for steel gr
...