SIST EN 1993-1-9:2025/oprA1:2026

Eurocode 3 - Design of steel structures - Part 1-9: Fatigue

1.1   Scope of EN 1993-1-9
(1) EN 1993-1-9 gives design methods for the verification of the fatigue design situation of steel structures.
NOTE   Steel structures consist of members and their joints. Each member and joint can be represented as a constructional detail or as several of the latter.
(2) Design methods other than the stress-based methods, such as the notch strain method or fracture mechanics methods, are not covered by EN 1993-1-9.
(3) EN 1993-1-9 only applies to structures made of all grades of structural steels and products within the scope of EN 1993-1 (all parts), in accordance with the provisions noted in the detail category tables or annexes.
(4) EN 1993-1-9 only applies to structures where execution conforms to EN 1090-2.
NOTE   Supplementary execution requirements are indicated in the detail category tables.
(5) EN 1993-1-9 applies to structures operating under normal atmospheric conditions and with sufficient corrosion protection and regular maintenance. The effect of seawater corrosion is not covered.
(6) EN 1993-1-9 applies to structures with hot dip galvanizing in accordance with the provisions noted in the detail category tables or annexes.
(7) Microstructural damage from high temperature (> 150°C) that occurs during the design service life is not covered.
(8) EN 1993-1-9 gives guidance of how to consider post-fabrication treatments that are intended to improve the fatigue resistance of constructional details.
1.2   Assumptions
(1) Unless specifically stated, EN 1990, EN 1991 (all parts) and EN 1993 1 (all parts) apply.
(2) The design methods given in EN 1993-1-9 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 on EN 1993 (all parts), or in the relevant material and product specifications.
(3) The design methods of EN 1993-1-9 are generally derived from fatigue tests on constructional details with large scale specimens that include effects of geometrical and structural imperfections from material production and execution (e.g. the effects of tolerances and residual stresses from welding).

Eurocode 3 - Calcul des structures en acier - Partie 1-9 : Fatigue

Eurocode 3 - Calcul des structures en acier - Partie 1-9 : Fatigue

Evrokod 3: Projektiranje jeklenih konstrukcij - 1-9. del: Utrujanje

1.1 Področje uporabe EN 1993-1-9
(1) EN 1993-1-9 določa metode projektiranja za preverjanje utrujenostnih projektnih situacij jeklenih konstrukcij.
OPOMBA Jeklene konstrukcije sestavljajo elementi in njihovi spoji. Vsak element in spoj se lahko predstavi kot konstrukcijska podrobnost ali kot več slednjih.
(2) Metode projektiranja, ki niso osnovane na napetostih, kot so metoda zareznih deformacij ali metode lomne mehanike, niso zajete v EN 1993-1-9.
(3) EN 1993-1-9 se uporablja samo za konstrukcije iz vseh vrst konstrukcijskih jekel in izdelkov v okviru EN 1993-1 (vsi deli), v skladu z določbami navedenimi v tabelah kategorij podrobnosti ali prilogah.
(4) EN 1993-1-9 se uporablja samo za konstrukcije, kjer izvedba ustreza EN 1090-2.
OPOMBA Dodatne zahteve za izvedbo so navedene v tabelah kategorij podrobnosti.
(5) EN 1993-1-9 se uporablja za konstrukcije, ki delujejo v normalnih atmosferskih pogojih in imajo zadostno protikorozijsko zaščito ter redno vzdrževanje. Učinek korozije morske vode ni zajet.
(6) EN 1993-1-9 se uporablja za konstrukcije s potopnim vročim cinkanjem v skladu z določbami navedenimi v tabelah kategorij podrobnosti ali prilogah.
(7) Mikrostrukturna poškodba zaradi visokih temperatur (> 150°C), ki se pojavi med projektirano življenjsko dobo, ni zajeta.
(8) EN 1993-1-9 daje smernice, kako upoštevati postopke po izdelavi, ki so namenjeni izboljšanju odpornosti konstrukcijskih podrobnosti proti utrujenosti.
1.2 Predpostavke
(1) Če ni posebej navedeno, veljajo EN 1990, EN 1991 (vsi deli) in EN 1993 1 (vsi deli).
(2) Metode projektiranja, navedene v EN 1993-1-9, so uporabne, če:
- kakovost izvedbe je kot določeno v EN 1090-2, in
- uporabljeni gradbeni materiali in izdelki so kot določeno v ustreznih delih EN 1993 (vsi deli) ali v ustreznih specifikacijah materialov in izdelkov.
(3) Metode projektiranja iz EN 1993-1-9 so na splošno izpeljane iz utrujenostnih preizkusov na konstrukcijskih podrobnostih z velikimi vzorci, ki vključujejo učinke geometrijskih in strukturnih nepopolnosti iz proizvodnje materiala in izvedbe (npr. učinki toleranc in preostalih napetosti zaradi varjenja).

General Information

• 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 1993-1-9:2025/prA1 - Eurocode 3 - Design of steel structures - Part 1-9: Fatigue

Relations

• Amends: kSIST FprEN 1993-1-9:2024 - Eurocode 3: Design of steel structures - Part 1-9: Fatigue
• Effective Date: 20-Jan-2026

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2026
Evrokod 3: Projektiranje jeklenih konstrukcij - 1-9. del: Utrujanje
Eurocode 3 - Design of steel structures - Part 1-9: Fatigue
Eurocode 3 - Calcul des structures en acier - Partie 1-9 : Fatigue
Eurocode 3 - Calcul des structures en acier - Partie 1-9 : Fatigue
Ta slovenski standard je istoveten z: EN 1993-1-9:2025/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 1993-1-9:2025
NORME EUROPÉENNE
EUROPÄISCHE NORM
prA1
May 2026
ICS 91.010.30
English Version
Eurocode 3 - Design of steel structures - Part 1-9: Fatigue
Eurocode 3 - Calcul des structures en acier - Partie 1-9 : Eurocode 3 - Calcul des structures en acier - Partie 1-9 :
Fatigue Fatigue
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 1993-1-9:2025. 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 1993-1-9:2025/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 Modifications to Clause 3, “Terms, definitions and symbols” . 5
4 Modifications to Clause 7, “Fatigue action effect” . 5
5 Modifications to Clause 8, “Fatigue resistance” . 6
6 Modifications to Clause 10, “Classified constructional details for the nominal stress
method” . 7
7 Modifications to Annex A, “Verification using cumulative linear damage model” . 8
8 Modifications to Annex B, “Hot spot stress method” . 9
9 Modifications to Annex C, “Effective notch stress method” . 11
10 Modifications to Annex D, “Recommendations for magnification factors k and stress
concentration factors k ” . 11
f
11 Modifications to Annex F, “Fatigue design of welded joints subjected to High Frequency
Mechanical Impact treatment” . 14
12 Modifications to Annex G, “Hot spot stress reference detail method” . 14
European foreword
This document (EN 1993-1-9:2025/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 an amendment to EN 1993-1-9:2025 and is currently submitted to the CEN Enquiry.
The following main changes to EN 1993-1-9:2025 are included in the amendment:
— Detail categories of stainless steel bolts and studs are added.
— The influence of shear stress is added to the detail with a cope hole in the web of a built-up girder
with and without thickness transitions.
— The highest detail categories for HFMI treated details in high-strengths steel is increased to 180.
— This amendment corrects technical and editorial points in EN 1993-1-9:2025 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
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”.
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”.
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”.
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 grades up to
S960;
EN 1993-1-13, Eurocode 3 — Design of Steel Structures — Part 1-13: Beams with large web openings;
EN 1993-1-14, Eurocode 3 — Design of Steel Structures — Part 1-14: Design assisted by finite element
analysis;
EN 1993-2, Eurocode 3 — Design of Steel Structures — Part 2: Bridges;
EN 1993-3, Eurocode 3 — Design of Steel Structures — Part 3: Towers, masts and chimneys;
EN 1993-4-1, Eurocode 3 — Design of Steel Structures — Part 4-1: Silos;
EN 1993-4-2, Eurocode 3 — Design of Steel Structures — Part 4-2: Tanks;
EN 1993-5, Eurocode 3 — Design of Steel Structures — Part 5: Piling;
EN 1993-6, Eurocode 3 — Design of Steel Structures — Part 6: Crane supporting structures;
EN 1993-7, Eurocode 3 — Design of Steel Structures — Part 7: Sandwich panels (under preparation).”.
0.5 In the list for national choices replace “7.1(5)” with “7.1(4)” and add “8.2(2)”.
3 Modifications to Clause 3, “Terms, definitions and symbols”
3.1.1.3 Modify the definition to read as follows:
“design concept in which an appropriate level of reliability for the fatigue design situation is obtained
without the need for regular in-service inspection or monitoring for fatigue cracks during the design
service life”.
3.1.1.4 Modify the definition to read as follows:
“design concept in which an appropriate level of reliability for the fatigue design situation is obtained by
implementing prescribed inspection and maintenance for detecting and mitigating fatigue cracks during
the design service life”.
3.1.1.16 Replace the title of Figure 3.2d) with:
“d) notch stress distribution”.
3.1.3.5 Replace the entire Note 1 to entry with:
“Note 1 to entry: The influence of stress ratio typically exists for non-welded constructional details and for welded
constructional details with thermal stress relief as specified in 7.4 and for welded constructional details with post-
weld treatment as specified in Annex F.”.
3.1.4.3 Delete Note 1 to entry and move Figure 3.6 to 3.1.4.4 after Note 1 to entry.
3.2.2 Add the following Latin lower-case letters:
“ stress concentration factor to account for the cope hole in the web within the constructional detail
f
co
flange thickness transition in girders
k reduction factor for fatigue resistance (in terms of stress) to account for simultaneously acting
τ
shear stresses
r radius of the cope hole in the web
co
t flange thickness”.
f
4 Modifications to Clause 7, “Fatigue action effect”
7.1(4) and (5) Replace (4) and (5) with:
“(4) For class 4 cross sections, the nominal stresses should be calculated with the effective cross section
according to EN 1993-1-5 in order to account for local instability effects.
NOTE The National Annex can give specifications for class 4 sections subject to fatigue actions.”.
7.3.2(1) Replace the first sentence with:
“For fatigue design situations where the fatigue action effect is defined by an equivalent constant stress
range, the design value of the nominal stress ranges Δσ and Δτ should be determined as follows:”.
e,2,Ed e,2,Ed
7.3.2(2) Replace the first sentence with:
“For fatigue design situations where the fatigue action effect is defined by an equivalent constant stress
range and where macro-geometric and/or concentrated load effects occur, the design value of the
modified nominal stress ranges Δσ and Δτ should be determined as follows:”.
e,2,Ed e,2,Ed
7.4(3) Replace the numbering of Formula (7.9) with (7.8), the numbering of Formula (7.10) with (7.9) and
the numbering of Formula (7.11) with (7.10).
5 Modifications to Clause 8, “Fatigue resistance”
8.1(1) Replace NOTE 1 with:
“NOTE 1 The characteristic fatigue resistance is represented by a series of parallel and equally spaced
fatigue resistance curves defining the number of cycles, N (endurance), that a stress range Δσ or Δτ can be
R
withstood by a constructional detail until failure occurs, as shown in Figures 8.1 to 8.4.”.
8.1(6) Delete the NOTE within Figure 8.2.
8.1(6), Table 8.1 Make the following changes within the Table 8.1:
— add within the block “8.1a” of the column “Figure” after detail category 80 a new line with: “71”in the
column detail category, with “71,0” in the column Δσ and with “46,0” in the column Δσ ;
D L
— delete in the block “8.1b” of the column “Figure” the four lines for detail categories 112, 100, 90 and 80;
and add after detail category 50 a new line with “45”in the column detail category, with “45,0” in the
column Δσ and with “20,6” in the column Δσ ;
D L
— replace in the block “8.2a” in the line for detail category 90 the value “36,5” in the column Δσ with
L
“36,4” and in the line for detail category 80 the value “59,0” in the column Δσ with “58,9” and in the
D
line for detail category 71 the value “28,8” in the column Δσ with “28,7”;
L
— replace in the block “8.2b” in the line for detail category 63 the value “36,9” in the column Δσ with
D
“36,8” and in the line for detail category 56 the value “32,8” in the column Δσ with “32,7” and in the
D
line for detail category 50 the value “29,3” in the column Δσ with “29,2” and the value “18,5” in the
D
column Δσ with “18,4”;
L
— replace in the block “8.3” in the line for detail category 90 the value “65,3” in the column Δσ with “65,2”
D
and add after detail category 71 a new line with: “63”in the column detail category, with “45,7” in the
column Δσ and with “35,4” in the column Δσ ; and replace in the line for detail category 50 the value
D L
“36,3” in the column Δσ with “36,2” and delete the whole line of detail category 45.
D
8.1(6), In Table 8.2, add after detail category 100 a new line with: “90”in the column detail category, with
“41,2” in the column Δτ and with “41,2” in the column Δτ to read as follows:
D L
“
Table 8.2 — Characteristic fatigue resistance values in N/mm from curves in Figure 8.4
Figure Detail category Slope parameter
∆τD ∆τL
2 2
[N/mm ] [N/mm ]
8.4 100 5 — 45,7 45,7
90 41,2 41,2
80 36,6 36,6
”.
8.2(2) Renumber the “NOTE” to “NOTE 1” and add NOTE 2 to read as follows:
“NOTE 2 The National Annex can give supplementary requirements on inspection of constructional details.”.
8.3.2(1) Replace NOTE 2 of (1) with:
“NOTE 2 Guidance is given in Annex F regarding fatigue design of welded joints subject HFMI treatment.”.
6 Modifications to Clause 10, “Classified constructional details for the nominal
stress method”
10(7), Table 10.1, Detail No. 5 Replace in last column:
“⑤ Thermal cut quality acc. to EN 9013 …” with “⑤ Thermal cut quality acc. to EN ISO 9013 …”.
10(7), Table 10.2, Detail No. 6, Within the block of constructional detail ⑥ add a new line with: “63
m =3” for the detail category and “Austenitic-ferritic stainless steel bolts and rods with cold rolled ISO
metric screw threads, subjected to normal stress” in the column “description”. Replace the description for
detail category 56 with “Carbon steel uncoated bolts and rods with rolled ISO metric screw threads, rolled
before heat treatment and austenitic stainless steel bolts and rods with cold rolled ISO metric screw
threads, subjected to normal stress” and the description for the first detail category 50 with “Carbon steel
hot-dip or electric galvanized bolts and rods with ISO metric screw threads, subjected to normal stress”
and the description for the second detail category 50 with “Carbon steel, austenitic stainless steel, and
austenitic-ferritic stainless steel bolts and rods with cut ISO metric screw threads, subjected to normal
stress”.
Table 10.3, Detail N
...