EN 1999-1-1:2023/prA1

Eurocode 9 - Design of aluminium structures - Part 1-1: General rules

EN 1999-1-1 gives basic design rules for structures made of wrought aluminium alloys and limited guidance for cast alloys (see Clause 5 and Annex C).
This document does not cover the following, unless otherwise explicitly stated in this document:
-              members with material thickness less than 0,6 mm;
-              welded members with material thickness less than 1,5 mm;
-              connections with:
-              steel bolts and pins with diameter less than 5 mm;
-              aluminium bolts and pins with diameter less than 8 mm;
-              rivets and thread forming screws with diameter less than 3,9 mm.

Eurocode 9 - Bemessung und Konstruktion von Aluminiumtragwerken - Teil 1-1: Allgemeine Bemessungsregeln

Eurocode 9 - Calcul des structures en aluminium - Partie 1-1: Règles générales

Evrokod 9 - Projektiranje konstrukcij iz aluminijevih zlitin - 1-1. del: Splošna pravila

EN 1999-1-1 podaja osnovna pravila za projektiranje konstrukcij iz kovanih aluminijevih zlitin in omejena navodila za litine (glej točko 5 in Prilogo C).
Ta dokument ne zajema naslednjega, razen če ni v tem dokumentu izrecno navedeno drugače:
- člani z debelino materiala manj kot 0,6 mm;
- varjeni člani z debelino materiala manj kot 1,5 mm;
- spoji z:
- jeklenimi vijaki in zatiči s premerom manj kot 5 mm;
- aluminijastimi vijaki in zatiči s premerom manj kot 8 mm;
- kovicami in vijaki za oblikovanje navojev s premerom manj kot 3,9 mm.

General Information

• Status: Not Published
• Publication Date: 01-Nov-2027
• ICS: 91.010.30 - Technical aspects
• ICS: 91.080.17 - Aluminium structures
• Technical Committee: CEN/TC 250 - Structural Eurocodes
• Drafting Committee: CEN/TC 250/SC 9 - Eurocode 9: Design of aluminium structures
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 26-Mar-2026
• Due Date: 31-Jan-2026
• Completion Date: 26-Mar-2026
• Mandate: M/515 - Mandate for amending existing Eurocodes and extending the scope of structural Eurocodes
• Ref Project: SIST EN 1999-1-1:2023/oprA1:2026 - Eurocode 9 - Design of aluminium structures - Part 1-1: General rules

Relations

• Referred By: EN ISO 41017:2024 - Facility management - Guidance on emergency preparedness and management of an epidemic (ISO 41017:2024)
• Effective Date: 28-Jan-2026
• Referred By: CEN ISO/TR 41016:2024 - Facility management - Overview of available technologies (ISO/TR 41016:2024)
• Effective Date: 28-Jan-2026
• Referred By: CEN ISO/TR 41030:2025 - Facility management - Existing performance management in facility management organizations - State of the industry (ISO/TR 41030:2024)
• Effective Date: 28-Jan-2026
• Amends: EN 1999-1-1:2023 - Eurocode 9 - Design of aluminium structures - Part 1-1: General rules
• Effective Date: 30-Jul-2025

Overview

EN 1999-1-1:2023/prA1 is a draft amendment to Eurocode 9 - Design of aluminium structures, Part 1-1: General rules, published by the European Committee for Standardization (CEN). This standard provides the foundational design rules for the structural use of wrought aluminium alloys and offers limited guidance for cast alloys in building and civil engineering structures. It supports the safe, efficient, and sustainable design of aluminium structures, and is intended for use alongside the broader suite of Eurocodes.

The document sets clear limits on its applicability. It does not cover:

• Members with material thickness less than 0.6 mm,
• Welded members with thickness below 1.5 mm,
• Connections with steel bolts/pins under 5 mm or aluminium bolts/pins under 8 mm,
• Rivets and thread forming screws below 3.9 mm diameter, unless specifically stated.

Key Topics

EN 1999-1-1:2023/prA1 covers essential aspects of aluminium structural design, such as:

• Material Properties: Defines requirements for both wrought and cast aluminium alloys, including specification of material constants, and consideration of heat-affected zones (HAZ).
• Structural Modelling and Analysis: Provides rules for joint modelling, stability calculations (global, local, and member buckling), and dealing with imperfections in frames and components.
• Cross-Section Classification: Details the classification and slenderness criteria for cross-section parts, taking into account the presence of welds and local buckling effects.
• Connections and Fastening Techniques: Addresses design of shear and tension connections, criteria for bolts, pins, welds, and rivets suitable for aluminium structures, including specific requirements for single lap joints and bolt-channel joints.
• Limit States and Durability: Establishes limit state criteria for structural safety under diverse loading conditions, as well as requirements for durability, corrosion protection, and long-term structural integrity.

Applications

This standard is vital for:

• Building and Civil Engineering Projects: Used by structural engineers for the design and verification of aluminium structures in buildings, bridges, and other infrastructure.
• Manufacturing and Fabrication: Offers guidance to manufacturers and fabricators in selecting appropriate aluminium alloys and designing connections adhering to modern performance and safety requirements.
• Compliance and Quality Assurance: Provides a reference for code compliance, structural safety verification, and harmonization with national annexes where regulatory safety factors may vary.
• Sustainable Construction: Supports lightweight design by enabling innovative, durable, and resilient aluminium solutions aligned with sustainable construction goals.

By following EN 1999-1-1:2023/prA1, professionals ensure that aluminium structures meet the latest European and international safety and performance standards.

Related Standards

For comprehensive application, EN 1999-1-1:2023/prA1 should be used together with other Eurocodes and standards, including:

• EN 1990-1: Eurocode - Basis of structural and geotechnical design - Part 1: New structures
• EN 1991: Actions on structures
• EN 1992 to EN 1998: Design standards for concrete, steel, composite, timber, masonry, and earthquake-resistant structures
• EN 19100: Eurocode 10 for structural glass (upcoming)
• EN 1999-1-3, EN 1999-1-4: Further parts for specific aluminium structural components

Key benefits of using EN 1999-1-1:2023/prA1 include harmonization across Europe, increased safety, and compatibility with contemporary advances in structural aluminium design.

Keywords: Eurocode 9, EN 1999-1-1:2023/prA1, aluminium structures, structural design, CEN, building standards, aluminium alloys, connections, buckling, durability, civil engineering, Eurocodes, safety compliance.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2026
Evrokod 9 - Projektiranje konstrukcij iz aluminijevih zlitin - 1-1. del: Splošna pravila
Eurocode 9 - Design of aluminium structures - Part 1-1: General rules
Eurocode 9 - Bemessung und Konstruktion von Aluminiumtragwerken - Teil 1-1:
Allgemeine Bemessungsregeln
Eurocode 9 - Calcul des structures en aluminium - Partie 1-1: Règles générales
Ta slovenski standard je istoveten z: EN 1999-1-1:2023/prA1
ICS:
91.010.30 Tehnični vidiki Technical aspects
91.080.17 Aluminijaste konstrukcije Aluminium structures
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
EN 1999-1-1:2023
NORME EUROPÉENNE
EUROPÄISCHE NORM
prA1
March 2026
ICS 91.010.30; 91.080.17
English Version
Eurocode 9 - Design of aluminium structures - Part 1-1:
General rules
Eurocode 9 - Calcul des structures en aluminium - Eurocode 9 - Bemessung und Konstruktion von
Partie 1-1: Règles générales Aluminiumtragwerken - Teil 1-1: Allgemeine
Bemessungsregeln
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 1999-1-1:2023. 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 1999-1-1:2023/prA1:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 5
1 Modifications throughout the whole document . 6
2 Modifications to the Introduction . 7
3 Modification to Clause 2, "Normative references" . 8
4 Modifications to 3.1, "Terms and definitions" . 8
5 Modifications to 3.2, "Symbols" . 8
6 Modification to 5.2.2, "Material properties for wrought and casting alloys" . 8
7 Modification to 5.2.5, "Design values of material constants" . 9
8 Modification to 7.1.2, "Joint modelling " . 9
9 Modification to 7.2.2, "Structural stability of frames" . 9
10 Modification to 7.3.2, "Imperfections for global analysis of frames" . 9
11 Modification to 8.1.4.3, "Slenderness parameters" . 9
12 Modifications to 8.1.4.4, "Classification of cross-section parts" . 9
13 Modifications to 8.1.5, "Local buckling resistance in class 4 members" . 10
14 Modification to 8.1.6.1, "General" . 10
15 Modification to 8.1.6.2, "Severity of softening" . 10
16 Modifications to 8.1.6.3, "Extent of HAZ" . 10
17 Modification to 8.2.2.2, "Net area" . 11
18 Modification to 8.2.8, "Bending and shear" . 11
19 Modification to 8.2.9, "Bending and axial force" . 11
20 Modification to 8.3.1.2, "Buckling resistance" . 11
21 Modification to 8.3.1.3, "Buckling curves" . 11
22 Modification to 8.3.3, "Members in bending and axial compression" . 11
23 Modification to 8.3.3.4, "Members containing localised welds" . 11
24 Modification to 8.5.1, "General" . 12
25 Modification to 8.5.2.2, "Constructional details" . 12
26 Modification to 8.6.1, "General" . 12
27 Modifications to 8.7.6, "Buckling load for orthotropic plates" . 12
28 Modification to 8.8.2, "Resistance of plate girders under in-plane bending" . 13
29 Modification to 8.8.4.1, "General" . 13
30 Modification to 8.8.4.2, "Plate girders with web stiffeners at supports" . 13
31 Modification to 8.8.4.3, "Plate girders with intermediate web stiffeners" . 13
32 Modification to 8.8.5.2, "Design resistance" . 13
33 Modification to 8.8.5.5, "Effective loaded length" . 13
34 Modification to 8.8.8.1, "Rigid end post" . 13
35 Modification to 8.8.8.5, "Welds" . 13
36 Modifications to 8.9.3, "Shear force resistance" . 13
37 Modification to 10.5.3.1, "Shear connections" . 14
38 Modifications to 10.5.3.2, "Tension connections" . 14
39 Modification to 10.5.8.1, "General" . 14
40 Modifications to 10.5.10, "Single lap joints of flats with only one row of fasteners" . 14
41 Modification to 10.5.12.1, "General" . 14
42 Modification to 10.6.2.2, "Characteristic strength of weld metal" . 14
43 Modification to 10.6.2.5.3, "Design resistance of HAZ for fillet welds" . 14
44 Modification to 10.6.2.7, "Bending about the weld seam axis for single-sided fillet welds
and butt welds" . 14
45 Modification to 10.9.2, "Bolt-channel joints" . 14
46 Modifications to 10.10.3.1, "General" . 14
47 Modification to B.4, "Modelling". 15
48 Modifications to B.6, "Use of imperfections" . 15
49 Modifications to B.9, "Limit state criteria" . 15
50 Modification to B.10, "Partial factors" . 15
51 Modification to C.3, "General" . 15
52 Modification to D.5.4.3, "Contact with timber" . 15
53 Modification to D.5.4.5, "Immersion in water" . 15
54 Modifications to F.3.2.2, "Bi-linear model" . 15
55 Modifications to F.3.2.3, "Tri-linear model". 16
56 Modifications to F.3.3.3, "Continuous models in the form ε = ε (σ)" . 17
57 Modification to F.4, "Approximate evaluation of ε " . 17
uni,max
58 Modifications to G.10.1, "Plastic section modulus" . 18
59 Modifications to H.5, "Boundary values for the ultimate axial load" . 18
60 Modifications to I.3.4, "Cantilevers with uniform cross-sections symmetrical about the
minor axis" . 18
61 Modifications to K.3, "Determination of ultimate bending moment M " . 19
u
62 Modification to O.2, "Scope and field of application". 19
63 Modification to O.3, "Tensile resistance" . 19
64 Modifications to R.4, "Design" . 19
65 Modification to S.2, "Scope and field of application" . 19
66 Modification to S.4.1.1, "Robustness" . 19
67 Modifications to S.4.1.2, "Design service life". 20
68 Modification to S.6, "Durability" . 20
69 Modifications to S.7.2, "Imperfections" . 20
70 Modification to S.8.3, "Buckling resistance of members" . 20
71 Modifications to S.9.2.2, "Road bridges" . 20
72 Modifications to S.9.2.3, "Foot bridges" . 20
73 Modifications to S.10.2, "Fatigue loading" . 20
74 Modifications to S.11.2.2, "Effects of global and local actions on decks" . 21
75 Modifications to S.11.2.3, "Surface finishing" . 22
76 Modification to S.11.2.4, "Replacement of existing decks with aluminium decks" . 22
77 Modifications to S.11.2.6, "Composite deck structures" . 23
78 Modifications to S.11.3.1, "Configurations of aluminium deep girders" . 23
79 Modification to S.11.3.2, "Detailing" . 23
80 Modifications to T.4.2, "Connection classification according to axial stiffness" . 23
81 Modifications to T.4.3, "Connection classification according to axial strength" . 23
82 Modifications to T.4.4, "Connections with bolts in shear" . 23
83 Modification to T.4.5, "Design of connections assisted by testing" . 24
84 Modifications to T.5.1, "Stability checks" . 24
85 Modifications to T.5.2, "Buckling length of members connected by gusset plates" . 24
86 Modifications to T.5.4, "Modelling of gusset plate connections subjected to axial force and
bending" . 24
87 Modification to U.1, "Use of this Annex" . 25
88 Modification to U.2, "Scope and field of application" . 25
89 Modifications to U.3, "General and main problems" . 25
90 Modification to U.4, "Calculation of Internal Forces" . 25
91 Modifications to U.4.1.1, "General" . 25
92 Modifications to U.4.1.2, "Effective width (“shear lag”)" . 25
93 Modifications to U.4.2.1, "Creep, shrinkage and cracking of concrete". 26
94 Modifications to U.4.3, "Elastic analysis with redistribution" . 26
95 Modification to U.5.1, "General" . 26
96 Modifications to U.5.2.1, "Plastic resisting moment of a composite cross section" . 26
97 Modifications to U.5.2.2, "Bending resistance of composite section from nonlinear theory"
............................................................................................................................................................................. 27
98 Modifications to U.6.1, "General rules" . 28
99 Modifications to U.6.2, "Traditional connectors" . 28
100 Deletion of U.6.3, "Innovative connectors" . 28
101 Modification to Bibliography . 28

European foreword
This document (EN 1999-1-1:2023/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 1999-1-1:2023.
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 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 references to EN 1990 with EN 1990-1.
Replace references to EN 1990:2023 with EN 1990-1:2023+A1:2026.
Replace references to EN 1999-1-3:2023 with EN 1999-1-3:2023+A1:2026.
Replace references to EN 1999-1-4:2023 with EN 1999-1-4:2023+A1:2026.
Replace “component” with “member” in the following clauses:
Clause/ Paragraph/ Number of Note
Subclause Figure/ Table occurrences
1.1 (1) 2
3.1.9  1
4.1.2 (2) 1
5.2.1 (1) 3 One of the occurrences is in NOTE 3
5.2.1 Table 5.2 1 The occurrence is in the title of Table 5.2
5.2.3.2 Table 5.8 1 The occurrence is in footnote a
6 (3) 1
8.1.1 (1) 1
10.5.1 (11) 2
10.9.2 (1) 1 The occurrence is in the NOTE
A.3.2 (1) 5 Three of the occurrences are in the NOTE
A.3.2 (2) 1 The occurrence is in the NOTE
A.4 (2) 2
A.4 (3) 5 All five occurrences are in NOTE 2
A.4 (4) 3 One of the occurrences is in the NOTE
A.4 (5) 2
A.5 (1) 2 One of the occurrences is in NOTE 1
B.3 (1) 1
B.6 (4) 1
C.4.1.2 (1) 1
C.4.1.3 (2) 1
C.4.2.3 (1) 1
D.5.3 (2) 2
D.5.4.8 Table D.3 2 Both occurrences are in footnote e
E.3.1 (1) 1
E.3.1 (4) 1
Clause/ Paragraph/ Number of Note
Subclause Figure/ Table occurrences
N.2 (3) 1 “component” appears two times in this
paragraph. Replace only the second
occurrence.
P.5.1 (1) 1
Q.3 (1) 1
Q.3 (2) 3
R.2 (1) 1
R.4 (9) 1
S.5.1 1 The occurrence is in title of S.5.1
S.11.2.1 (2) 1
S.11.2.2 (2) 1 The occurrence is in NOTE 1
T.4.3 (6) 1
T.4.4 (4) 1
V.2 (1) 2 Both occurrences are in NOTE 2b

2 Modifications to the Introduction
In 0.1, replace the list with the following:
“
— EN 1990 Eurocode — Basis of structural and geotechnical design
— EN 1991 Eurocode 1 — Actions on structures
— EN 1992 Eurocode 2 — Design of concrete structures
— EN 1993 Eurocode 3 — Design of steel structures
— EN 1994 Eurocode 4 — Design of composite steel and concrete structures
— EN 1995 Eurocode 5 — Design of timber structures
— EN 1996 Eurocode 6 — Design of masonry structures
— EN 1997 Eurocode 7 — Geotechnical design
— EN 1998 Eurocode 8 — Design of structures for earthquake resistance
— EN 1999 Eurocode 9 — Design of aluminium structures
— EN 19100 Eurocode 10 — Design of structural glass
— New parts are under development, e.g. Eurocode for design of fibre-polymer composite structures
and design of tensioned membrane structures”.
In 0.2, replace the fourth paragraph with the following:
“For the design of new structures, EN 1999 (all parts) is intended to be used, for direct application,
together with EN 1990-1 and the other Eurocodes.”.
3 Modification to Clause 2, "Normative references"
Replace “EN 1990, Eurocode — Basis of structural and geotechnical design”
with
“EN 1990-1, Eurocode — Basis of structural and geotechnical design — Part 1: New structures”.
4 Modifications to 3.1, "Terms and definitions"
In the definition for term 3.1.4, add “and stiffness” after “structural” and delete Notes 1 and 2 to entry.
In the definition for term 3.1.5, delete Notes 1 and 2 to entry.
5 Modifications to 3.2, "Symbols"
Replace the definition of “F ” with the following:
vp,Rd
“design value of shear resistance of the screw for loads within -120° ≤ θ ≤ -60° (opposite the opening of
the groove)”.
Delete “L” and definition.
Delete “h” and definition.
Delete “u-u” and definition.
Delete “v-v” and definition.
Replace “β , β , β ” with “β , β ”.
1 2 3 2 3
Delete “δ ” and definition.
q
Replace “λ ” with “λ ”.
c1, c,l
Add “, correction factor” after “slip factor, efficiency factor” in the definition of “μ”.
Replace “ρ ” with “ρ ”.
c,1 c,l
Delete “σ ” and definition.
cr
Delete “σ ” and definition.
cr0
6 Modification to 5.2.2, "Material properties for wrought and casting alloys"
Replace “should” with “shall” in footnote c in Table 5.4.
7 Modification to 5.2.5, "Design values of material constants"
Replace “α” with “α ” in the fourth bullet point in (1).
T
8 Modification to 7.1.2, "Joint modelling "
Replace the second and third bullet points in (2) with the following:
“
— For semi-continuous joint model, the structural and stiffness properties of the joint components
need explicit consideration for its modelling in the global analysis;
— For continuous joint model, only the structural properties of the members need to be considered in
the global analysis.”.
9 Modification to 7.2.2, "Structural stability of frames"
Replace “lateral” with “torsional” in the second to last sentence in (6).
10 Modification to 7.3.2, "Imperfections for global analysis of frames"
λ
Replace “Note 2” with “Note 4” in the definition of “ ” in the key to Formula (7.7).
m
11 Modification to 8.1.4.3, "Slenderness parameters"
Add “stiffeners” at the end of the definition of “a” in the key to Figure 8.4.
12 Modifications to 8.1.4.4, "Classification of cross-section parts"
Add the following after (1) and renumber the following paragraph:
“(2) In Table 8.1 and Table 8.2, a cross-section part should be considered with welds if it contains
longitudinal welding at an edge or at any point within its width. Cross-s
...