SIST EN 1993-1-6:2025/oprA1:2026

• Abstract:

  1.1 Scope ; (1) EN 199316 provides rules for the structural design of plated steel structures that have the form of a shell of revolution (axisymmetric shell).; (2) This document is applicable to unstiffened fabricated axisymmetric shells formed from isotropic rolled plates using both algebraic and computational procedures, and to stiffened axisymmetric shells with different wall constructions using computational procedures. It also; applies to associated circular or annular plates and to beam section rings and stringer stiffeners where they form part of the complete shell structure. The general computational procedures are applicable to all shell forms.; (3) This document does not apply to manufactured shells or to shell panels or to elliptical shell forms, except that its computational procedures are applicable to all shell structures. This document does not apply to structures under seismic or other dynamic loading. It does not cover the aspects of leakage of stored liquids or solids.; (4) Cylindrical and conical panels are not explicitly covered by this document. However, the provisions of 9.8 can be used provided that appropriate boundary conditions are taken into account.; (5) This document defines the characteristic and design values of the resistance of the structure.; (6) This document is concerned with the requirements for design against the ultimate limit states of:; — plastic failure;; — cyclic plasticity;; — buckling;; — fatigue.; (7) Overall equilibrium of the structure (sliding, uplifting, overturning) is not included in this document. Special considerations for specific applications are included in the relevant application parts of EN 1993.; (8) Detailed formulae for the simple calculation of unstiffened cylinders, cones and spherical domes are given in the Annexes.; (9) Provisions for simple calculations on specific stiffened shell types are given in EN 199341.; (10) This document is intended for application to steel shell structures. Where no standard exists for shell structures made of other metals, including high strength steels, the provisions of this document are applicable provided the appropriate material properties of the metal are taken into account.; (11) The provisions of this document are intended to be applied within the temperature ranges defined in the relevant EN 1993 application parts.; (12) Where no application part defines a different range, this document applies to structures within the following limits:; — design metal temperatures lie within the range −50 °C to +100 °C, except when using the special provisions given in 5.1;; — radius to thickness ratios (r/t) within the range 50 to 2 000;; — manufactured circular hollow sections according to EN 10210 and EN 10219 are outside the scope of this document and are covered by EN 199311.; However, if no other provisions are available, the rules of this document are useful for manufactured circular hollow sections. In; particular, this document is applicable to the design of manufactured piles (see EN 19935) provided the imperfections and tolerance requirements of EN 19935 are adopted in place of those specified in this document, and where no other standard covers the specific pile geometry.; NOTE 1 Experimental and theoretical data relating to manufactured circular hollow sections were not considered when this document was drafted. The application of this document to such structures therefore remains the responsibility of the user.; NOTE 2 The stress design rules of this document can be rather conservative if applied to some geometries and loading conditions for relatively thickwalled shells.; NOTE 3 Thinner shells than r/t = 2 000 can be treated using these provisions but the provisions have not been verified for such thin shells.; NOTE 4 The maximum temperature is restricted so that the influence of creep can be ignored where high temperature creep effects are not covered by the relevant application part.; [...]

• Status: Not Published
• Public Enquiry End Date: 26-Nov-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: 25-Sep-2026
• Due Date: 12-Feb-2027
• Mandate: M/515 - Mandate for amending existing Eurocodes and extending the scope of structural Eurocodes
• Ref Project: EN 1993-1-6:2025/prA1 - Eurocode 3 - Design of steel structures - Part 1-6: Strength and stability of shell structures

• Amends: kSIST FprEN 1993-1-6:2024 - Eurocode 3 - Design of steel structures - Part 1-6: Strength and Stability of Shell Structures
• Effective Date: 10-Jun-2026

SIST EN 1993-1-6:2025/oprA1:2026 is a draft amendment to EN 1993-1-6:2025, the Eurocode 3 part for the strength and stability of steel shell structures. It updates the shell design rules for axisymmetric steel shells, with emphasis on buckling checks, tolerance assessment, and the calculation methods used by designers and analysts.

What does SIST EN 1993-1-6:2025/oprA1:2026 specify?

SIST EN 1993-1-6:2025/oprA1:2026 modifies EN 1993-1-6:2025. EN 1993-1-6 gives rules for the structural design of plated steel structures that have the form of a shell of revolution, including unstiffened fabricated axisymmetric shells from isotropic rolled plates and stiffened axisymmetric shells assessed with computational procedures.

The document also applies to associated circular or annular plates and to beam section rings and stringer stiffeners when they form part of the complete shell structure. It excludes manufactured shells, shell panels and elliptical shell forms, and it does not cover seismic or other dynamic loading or leakage of stored liquids or solids. The rules are aimed at ultimate limit states for plastic failure, cyclic plasticity, buckling and fatigue, with overall equilibrium checks handled elsewhere.

The amendment is organized as whole-document updates plus targeted changes to the Introduction, Clause 2, Clause 5, Clause 6, Clause 9, Annex A, Annex D and Annex E.

Annex	What it covers
Annex A	Membrane theory stresses in unstiffened shells
Annex D	Buckling resistance of unstiffened shells when using stress design
Annex E	Buckling resistance of unstiffened shells when using reference resistance design

What are the key requirements of SIST EN 1993-1-6:2025/oprA1:2026?

The amendment keeps the document focused on shell structures and updates several calculation points that matter in design, checking and inspection.

• Scope limits - The rules apply within the stated temperature range of -50 °C to +100 °C, unless special provisions apply, and within radius-to-thickness ratios from 50 to 2 000. In practice, this tells you when the shell rules are meant to be used and when another part of Eurocode 3 or another assessment route is needed.
• Reference framework - Clause 2 and the whole document now use EN 1990-1 where EN 1990 was previously referenced. In practice, calculation notes and software references should be checked against the updated basis standard.
• Tolerance checks - Clause 9.4.1 clarifies how to judge buckling-relevant tolerances obtained from laser scanning of the complete unloaded structure. Clause 9.4.5 clarifies the thickness to use for a meridional gauge when a dimple tolerance check crosses a weld. In practice, inspection records need to use the correct measured amplitude and the correct plate thickness at the weld.
• Buckling limit state - Clause 9 keeps buckling as a core limit state and updates the treatment of several formulas and references in the LS3 checks. In practice, the amendment affects how shell instability is quantified in the design calculation.
• GMNIA resistance - Figure 9.10 defines buckling resistance from a General Nonlinear Imperfection Analysis (GMNIA). In practice, analysis reports should identify which measure controls the resistance value and how deformation and load factor were obtained.
• Annex D - Annex D corrects the stress-design formula set and revises the top ring stiffness method for a stepped wall shell. It also states when a Linear Buckling Analysis (LBA) or a General Nonlinear Analysis (GNA) should be used for the ring at the upper edge. In practice, this matters for ring sizing and for deciding when a more detailed stability analysis is required.
• Annex E - Annex E adds the shell cross-sectional area definition used in reference resistance design. In practice, this supports consistent resistance calculations for unstiffened shells.

What terms does SIST EN 1993-1-6:2025/oprA1:2026 define?

• Axisymmetric shell - A shell of revolution whose geometry is symmetric around an axis.
• Unstiffened shell - A shell wall without added stiffeners.
• Stiffened shell - A shell wall that includes stiffeners such as rings or stringers.
• Buckling limit state (LS3) - The limit state used for shell stability checks against buckling.
• Linear Buckling Analysis (LBA) - A stability analysis used in Annex D to verify ring adequacy for short shells.
• General Nonlinear Analysis (GNA) - A nonlinear analysis used in Annex D to verify ring adequacy for longer shells.
• General Nonlinear Imperfection Analysis (GMNIA) - A nonlinear analysis with imperfections used to define buckling resistance in Figure 9.10.

Who uses SIST EN 1993-1-6:2025/oprA1:2026?

Structural engineers, finite element analysts and checking engineers use SIST EN 1993-1-6:2025/oprA1:2026 when designing steel shell structures and assessing buckling resistance. Quality and inspection teams use it for tolerance verification, including laser-scan-based imperfection checks and weld-related gauge checks. It is also relevant to fabricators, buyers and approval bodies that need to confirm which shell forms, analysis methods and annex formulae apply to a project.

What changed in SIST EN 1993-1-6:2025/oprA1:2026 from the previous edition?

SIST EN 1993-1-6:2025/oprA1:2026 will modify EN 1993-1-6:2025. The foreword lists clarifications on laser-scanned buckling tolerances and on thickness selection for a weld-crossing dimple check, a correction to the top ring stiffness method for stepped wall shells, and editorial and typing corrections throughout the document. The amendment also updates internal references to EN 1990-1, revises Figure 9.10, and corrects formulas in Annex D and Annex E.

Which standards are used with SIST EN 1993-1-6:2025/oprA1:2026?

• EN 1990-1 - The updated basis standard referenced in Clause 2 and throughout the text.
• EN 1993-1-14:2025 - Provides design assisted by finite element analysis, cited for shell design work in Clause 5.
• EN 1993-1-11 - Covers manufactured circular hollow sections, which the scope places outside this document.
• EN 1993-5 - Provides piling provisions when the shell rules are applied to manufactured piles.
• EN 10210 and EN 10219 - Product standards for manufactured circular hollow sections mentioned in the scope.

What does the SIST EN 1993-1-6:2025/oprA1:2026 document contain?

The amendment contains targeted text changes rather than a new design method. It updates references in the Introduction and Clause 2, revises material and geometry wording in Clause 5, changes structural analysis text in Clause 6, and adjusts several buckling-limit-state items in Clause 9.

Annex A keeps the membrane-theory stress content for unstiffened shells, with a table correction. Annex D contains the main stress-design formula set for buckling resistance, including the revised top-ring procedure and analysis triggers. Annex E contains the reference-resistance design formulas and the added definition for shell cross-sectional area.

SLOVENSKI STANDARD
01-november-2026
Evrokod 3 - Projektiranje jeklenih konstrukcij - 1-6. del: Trdnost in stabilnost
lupinastih konstrukcij
Eurocode 3 - Design of steel structures - Part 1-6: Strength and stability of shell
structures
Eurocode 3 - Bemessung und Konstruktion von Stahlbauten - Teil 1-6: Festigkeit und
Stabilität von Schalen
Eurocode 3 - Calcul des structures en acier - Partie 1-6: Résistance et stabilité des
structures en coque
Ta slovenski standard je istoveten z: EN 1993-1-6:2025/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 1993-1-6:2025
NORME EUROPÉENNE
EUROPÄISCHE NORM
prA1
September 2026
ICS 91.010.30; 91.080.13
English Version
Eurocode 3 - Design of steel structures - Part 1-6: Strength
and stability of shell structures
Eurocode 3 - Calcul des structures en acier - Partie 1-6: Eurocode 3 - Bemessung und Konstruktion von
Résistance et stabilité des structures en coque Stahlbauten - Teil 1-6: Festigkeit und Stabilität von
Schalen
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 1993-1-6:2025. 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 1993-1-6:2025/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 2, "Normative references" . 5
4 Modification to Clause 5, "Materials and geometry" . 5
5 Modification to Clause 6, "Structural analysis" . 5
6 Modifications to Clause 9, “Buckling Limit State (LS3)” . 5
7 Modification to Annex A (informative), “Membrane theory stresses in unstiffened shells” 6
8 Modifications to Annex D (normative), “Formulae to determine the buckling resistance of
unstiffened shells when using stress design” . 6
9 Modification to Annex E (normative), “Formulae to determine the buckling resistance of
unstiffened shells when using reference resistance design” . 7

European foreword
This document (EN 1993-1-6:2025/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 1993-1-6:2025.
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 1993-1-6:2025 are included in the amendment:
— clarification on the interpretation of buckling-relevant tolerances obtained with laser scanning of the
complete unloaded structure (subclause 9.4.1),
— clarification on thickness to be associated with a meridional gauge where dimple tolerance check is
being done across a weld (subclause 9.4.5),
— correction of the method to determine the minimum stiffness of a top ring in a stepped wall shell
(subclause D.5.3.4.2),
— correction of several wordings and typing errors throughout the document.
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
Replace “EN 1990:2023” with “EN 1990-1:2023+A1:2026” throughout the text when a dated referenc
...