SIST EN 1993-1-13:2024/oprA1:2026

• 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
• Public Enquiry End Date: 29-Jul-2026
• ICS: 91.010.30 - Technical aspects
• ICS: 91.080.13 - Steel structures
• Technical Committee: KON - Structures
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 10-Jun-2026
• Due Date: 28-Oct-2026
• Ref Project: EN 1993-1-13:2024/prA1 - Eurocode 3 - Design of steel structures - Part 1-13: Beams with large web openings

• Amends: kSIST FprEN 1993-1-13:2023 - Eurocode 3 - Design of steel structures - Part 1-13: Beams with large web openings
• Effective Date: 20-Jan-2026

SIST EN 1993-1-13:2024/oprA1:2026 is the Slovenian adoption of draft amendment prA1 to EN 1993-1-13:2024, prepared by CEN for enquiry. It amends Eurocode 3 Part 1-13, which gives supplementary rules for the design of steel beams with large web openings. The document is used by structural designers and others who need to verify steel beams with openings for local resistance, global behaviour and related stability effects.

What does SIST EN 1993-1-13:2024/oprA1:2026 specify?

SIST EN 1993-1-13:2024/oprA1:2026 specifies amendments to EN 1993-1-13:2024 rather than a separate design method. The underlying part applies to rolled and welded steel beams with large web openings, including circular, hexagonal and sinusoidal openings, and to openings that are single, widely spaced or closely spaced.

The underlying scope is for uniform I or H profiles symmetric about the weak axis, with web slenderness up to 121ε. It also includes openings reinforced by longitudinal and/or transverse stiffeners, and it addresses sagging and hogging bending moments.

The amendment is organized as changes to:

• the whole document
• the Introduction
• Clause 1, Scope
• Clause 3, Terms and definitions
• Clause 4, Basis of design
• Clause 7, Structural Analysis
• Clause 8, Ultimate Limit States
• Clause 9, Serviceability limit states

What are the key requirements of SIST EN 1993-1-13:2024/oprA1:2026?

SIST EN 1993-1-13:2024/oprA1:2026 tightens the definition of when this Eurocode part applies and updates how the main resistance checks are carried out. In practice, the amendment makes it clearer when an opening is “large” and how to check the beam around it.

When the part applies

The amendment defines a large web opening as an opening for which global shear and bending checks of the net section are not enough and local effects must also be considered. It applies when the opening cannot fit within the specified envelope, when it is eccentric to the flange, or when openings are closely spaced. Fastener holes are handled with EN 1993-1-1 instead.

What must be checked

The document covers resistance at the openings and the effect of those openings on the global beam behaviour, including lateral torsional buckling. That means the designer must look not only at the local opening area, but also at the beam as a whole.

How the design checks change

Clause 4 adds resistance to web buckling next to widely spaced openings to the basis of design. Clause 8 updates the ULS checks for shear, bending and Vierendeel bending, and it refines the calculation of end-post and web-post behaviour.

For web-post buckling, the amendment improves the choice of buckling curves and ties the selection to rolled or welded sections. For end-post resistance, it improves the calculation method and updates the treatment of connection details and local load transfer.

How openings and connections are treated

The amendment keeps the alternative increment methods for circular and sinusoidal openings, which are aimed at computer methods. It also updates the rules for end plate, fin plate and angle connections, including notched arrangements and stiffened openings.

How deflection and serviceability feed into resistance

The serviceability checks matter because the ULS eccentricity across an opening is taken from the doubled relative deflection at SLS. In practice, serviceability deflection is not only a comfort or appearance check - it is also used in the resistance calculation.

What terms does SIST EN 1993-1-13:2024/oprA1:2026 define?

• large web opening - an opening that needs local opening checks in addition to global shear and bending verification.
• web-post - the web region between adjacent openings, checked for buckling.
• end-post - the web region at the end opening, checked for resistance and buckling.
• Vierendeel bending - local bending around the opening ends that contributes to force redistribution.
• sagging (positive) bending moment - bending that puts the bottom of the beam in tension under the stated sign convention.
• hogging (negative) bending moment - bending that reverses the sign convention and changes which parts of the beam are in tension or compression.
• ULS - ultimate limit state, the resistance and safety check level.
• SLS - serviceability limit state, the deflection and function check level.

Who uses SIST EN 1993-1-13:2024/oprA1:2026?

SIST EN 1993-1-13:2024/oprA1:2026 is used by structural engineers, steelwork designers, detailers and checking engineers who design beams with large web openings. It is also relevant for steel fabricators, contractors and quality managers who need to understand the opening type, stiffening, connection details and execution requirements. Buyers and specifiers use it when they need to identify the correct design route for steel beams with web openings in buildings and other steel structures.

What changed in SIST EN 1993-1-13:2024/oprA1:2026 from the previous edition?

This amendment to EN 1993-1-13:2024 introduces the following main changes:

• it clarifies the definition of large web openings
• it improves the choice of buckling curves for web-post buckling
• it improves the calculation method for end-post resistance
• it corrects technical and editorial points to improve clarity and usability

Which standards are used with SIST EN 1993-1-13:2024/oprA1:2026?

• EN 1990-1 - basis of structural and geotechnical design for new structures.
• EN 1991 series - actions on structures.
• EN 1993-1-1 - general rules, including the material parameter ε and checks used where this part refers back to general steel design.
• EN 1993-1-2 - structural fire design.
• EN 1993-1-5 - plated structural elements, including transverse stiffener design.
• EN 1993-1-9 - fatigue design.
• EN 1090-2 - execution quality for steel structures.

What does the SIST EN 1993-1-13:2024/oprA1:2026 document contain?

The document contains amendments to the scope, definitions, design basis, structural analysis, ULS rules and SLS rules of EN 1993-1-13:2024. It updates several formulas, references, table entries and Figure 8.6, including the treatment of opening geometry, end-posts, web-post buckling and local load transfer. It also links serviceability deflection to the ultimate limit state treatment of opening eccentricity. These changes support design and verification work for beams with large web openings rather than testing or certification.

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
...