SIST EN 1991-1-4:2026/oprA1:2026

• Abstract:

  1.1 Scope of EN 1991-1-4; (1) This document gives rules for the determination of natural wind actions for the structural design of building and civil engineering works for each of the loaded areas under consideration. This includes actions applied to the whole structure or parts of it, as well as wind-exposed elements attached to the structure.; (2) This document is applicable to:; - buildings and other civil engineering works with heights up to 200 m;; - guyed masts, other open lattice structures and chimneys with heights up to 300 m;; - bridges having no span greater than 200 m.; (3) The rules contained in this document allow the evaluation of characteristic wind actions on land-based structures.; (4) This document is applicable to offshore coastal structures.; NOTE Additional or amended provisions can be necessary.; (5) This document does not give guidance on non-synoptic winds (e.g. thunderstorms, downbursts, microbursts, tornadoes, etc.), mixed wind climates, nor does it give guidance on how to account for local effects (e.g. thermal effects, funnelling, strong arctic thermal surface inversion, etc.).; (6) This document addresses simplified procedures for dynamic effects, mostly based on the assumption of a dominant single-mode response (see Annex E, Annex F and Annex G). General criteria for performing a full dynamic analysis under aerodynamic excitation are not treated in this document.; (7) Wind pressure effects of passing vehicles are outside the scope of this document.; NOTE See EN 1991 2 for wind effects from passing trains.; 8) This document also provides guidance on wind tunnel testing and numerical modelling which can be needed or desirable when the shape or structural behaviour are unusual or do not strictly fall within the rules of the document, or in cases of unusual orography or other surroundings.; 1.2 Assumptions; (1) The assumptions given in EN 1990-1:2023+A1:2026, 1.2 apply.

• Status: Not Published
• Public Enquiry End Date: 29-Oct-2026
• ICS: 91.010.30 - Technical aspects
• Technical Committee: KON - Structures
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 21-Aug-2026
• Due Date: 08-Jan-2027
• Ref Project: EN 1991-1-4:2026/prA1 - Eurocode 1 - Actions on structures - Part 1-4: Wind actions

• Amends: kSIST FprEN 1991-1-4:2025 - Eurocode 1 - Actions on structures - Part 1-4: Wind actions
• Effective Date: 06-May-2026

SIST EN 1991-1-4:2026/oprA1:2026 is the Slovenian draft amendment to EN 1991-1-4:2026 on Eurocode 1 wind actions. It updates the rules used to determine natural wind actions for the structural design of buildings, civil engineering works, bridges, masts, chimneys, and wind-exposed elements attached to them.

What does SIST EN 1991-1-4:2026/oprA1:2026 specify?

SIST EN 1991-1-4:2026/oprA1:2026 modifies the wind-action rules in EN 1991-1-4:2026. The base document covers characteristic wind actions on land-based structures and offshore coastal structures, and it is intended for buildings up to 200 m, guyed masts, other open lattice structures and chimneys up to 300 m, and bridges with no span greater than 200 m.

The scope excludes non-synoptic winds, mixed wind climates, local effects such as funnelling and thermal effects, and wind pressure from passing vehicles. It also notes simplified procedures for dynamic effects and gives guidance for wind tunnel testing and numerical modelling where the structure, shape, or surroundings are unusual.

Annex	What it covers
A	Terrain effects
B	Pressure coefficients for pressures on surfaces
C	Net pressure coefficients and force coefficients for canopies
D	Force coefficients and friction coefficients
E	Procedure for along-wind dynamic response
F	Procedure for across-wind and torsional actions on susceptible buildings
G	Procedure for across-wind dynamic and aeroelastic response of slender structures
H	Dynamic characteristics of structures with linear elastic behaviour
I	Response of steel lattice towers and guyed masts

What are the key requirements of SIST EN 1991-1-4:2026/oprA1:2026?

The amendment mainly updates how wind actions are modelled, which coefficients are selected, and how dynamic response is checked. In practice, it affects the choice of pressure coefficients, the treatment of terrain and height, and the formulas used for slender or dynamically sensitive structures.

• Clause 1 extends the scope to the preliminary design stage of buildings and civil engineering works up to 300 m, and adds a note pointing to Annex A for wind profiles up to 300 m. This matters when wind loading is needed before the final structural layout is fixed.
• Clause 3 and Clause 5 adjust symbols and wording, including the symbol for kinematic viscosity of air and the notation in Formula (5.1). This matters because the design equations must be read with the updated symbols.
• Clause 6 updates wind velocity and velocity pressure wording, including a note linking the Gumbel distribution to its parameters and a revised direction figure. This affects how wind speed data and direction sectors are interpreted.
• Annex A revises terrain effects, including terrain category IV and the way the wind profile is handled in the updated formulas. This matters for exposure assessment and wind speed variation with height.
• Annex B is the main technical update. It separates external global and external local pressure coefficients, ties them to loaded area limits, and revises the reference height rules for buildings with h ≤ 6b and h > 6b. It also updates roof, canopy, tank, silo, and signboard figures, which are the details used in surface pressure checks.
• Annex C updates canopy coefficients and signboard reference rules. This is the part to use when wind acts on canopy-type structures rather than on normal walls and roofs.
• Annex D revises force and friction coefficients and adds bridge-related guidance when pedestrian traffic is considered simultaneously with wind. The note on fundamental basic wind velocity v_b0 is important because the National Annex can change the value used in that combination.
• Annexes E, F, G, H and I update the dynamic-response procedures, mode-shape descriptions, frequency definitions, and the response of steel lattice towers and guyed masts. These annexes are used when wind loading is not purely static.

What terms does SIST EN 1991-1-4:2026/oprA1:2026 define?

• Natural wind actions - wind actions determined from atmospheric wind for structural design.
• Characteristic wind actions - the wind actions the document evaluates for design use.
• Tributary area - the area that contributes to the wind action on a small element or fixing.
• External global pressure coefficients - coefficients used for overall wind pressure on larger loaded areas.
• External local pressure coefficients - coefficients used for small elements and fixings with small tributary areas.
• Reference height z_e - the height used to select coefficients for a surface zone or part of a building.
• Fundamental basic wind velocity v_b0 - the basic wind speed used in the bridge-related pedestrian combination note.

Who uses SIST EN 1991-1-4:2026/oprA1:2026?

Structural engineers, civil engineers, and wind engineering specialists use it to determine design wind actions and check structural resistance. Bridge designers use the bridge-related clauses and the pedestrian combination note, while designers of canopies, towers, masts, chimneys, tanks, silos, and signboards use the annexes with geometry-specific coefficients. Quality and checking teams use the document to verify that the selected coefficients, terrain assumptions, and National Annex choices match the project.

What changed in SIST EN 1991-1-4:2026/oprA1:2026 from the previous edition?

SIST EN 1991-1-4:2026/oprA1:2026 is a draft amendment to EN 1991-1-4:2026 and, if approved, will supersede that edition. The stated changes include:

• an expanded scope for preliminary design up to 300 m;
• updates to symbols, formulas, and wording in Clauses 3, 5 and 6;
• major revisions to pressure coefficients and geometry rules in Annex B;
• updates to canopy, tank, silo, and signboard provisions in Annexes C and D;
• revised dynamic-response procedures in Annexes E, F and G;
• updates to dynamic characteristics and tower/mast response in Annexes H and I.

Which standards are used with SIST EN 1991-1-4:2026/oprA1:2026?

• EN 1990-1:2023+A1:2026 - provides the assumptions that apply to this document and is cited for pedestrian/wind combination context.
• EN 1991-2 - is cited for wind effects from passing trains.

What does the SIST EN 1991-1-4:2026/oprA1:2026 document contain?

The document contains amendment text for clauses, tables, formulas, notes, and figures across the wind-action model. Most of the technical detail is in Annex B, where the pressure coefficients and zone figures are updated for walls, roofs, canopies, tanks, silos, and signboards. It also contains revised procedures in Annexes E, F and G for along-wind, across-wind, torsional, and aeroelastic response. These contents are used in structural design calculations, wind tunnel assessment, and numerical modelling checks.

SLOVENSKI STANDARD
01-oktober-2026
Evrokod 1 - Vplivi na konstrukcije - 1-4. del: Vplivi vetra
Eurocode 1 - Actions on structures - Part 1-4: Wind actions
Eurocode 1 - Einwirkungen auf Tragwerke - Teil 1-4: Windlasten
Eurocode 1 - Actions sur les structures - Partie 1-4 : Actions du vent
Ta slovenski standard je istoveten z: EN 1991-1-4:2026/prA1
ICS:
91.010.30 Tehnični vidiki Technical aspects
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
EN 1991-1-4:2026
NORME EUROPÉENNE
EUROPÄISCHE NORM
prA1
July 2026
ICS
English Version
Eurocode 1 - Actions on structures - Part 1-4: Wind actions
Eurocode 1 - Actions sur les structures - Partie 1-4 : Eurocode 1 - Einwirkungen auf Tragwerke - Teil 1-4:
Actions du vent Windlasten
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 1991-1-4:2026. 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 1991-1-4:2026/prA1:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Modification throughout the whole document . 4
2 Modification to European Foreword . 4
3 Modification to “Introduction” . 4
4 Modification to Clause 1, “Scope” . 4
5 Modification to Clause 3, “Terms, definitions and symbols” . 4
6 Modification to Clause 5, "Modelling of wind actions" . 4
7 Modification to Clause 6, "Wind velocity and velocity pressure” . 4
8 Modification to Annex A, “Terrain effects” . 5
9 Modification to Annex B, “Pressure coefficients for pressures on surfaces” . 5
10 Modification to Annex C, “Net pressure coefficients and force coefficients for
canopies” . 11
11 Modification to Annex D, “Force coefficients and friction coefficients” . 12
12 Modification to Annex E, “Procedure for along-wind dynamic response” . 13
13 Modification to Annex F, “Procedure for across-wind and torsional actions on
susceptible buildings” . 15
14 Modification to Annex G, “Procedure for across-wind dynamic and aeroelastic
response of slender structures” . 15
15 Modification to Annex H, “Dynamic characteristics of structures with linear elastic
behaviour” . 15
16 Modification to Annex I, “Response of steel lattice towers and guyed masts” . 15

European foreword
This document (EN 1991-1-4:2026/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 supersede EN 1991-1-4:2026.
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 recognise 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 Modification throughout the whole document
Modify the symbol for the kinematic viscosity of the air “ν” to “ν ”.
air
2 Modification to European Foreword
Add the word “structures” between “slender” and “with” in list item a).
Add “guidance on” between “of” and “an” in list item c).
3 Modification to “Introduction”
0.5 Add the following references in the table with national choices: "B.3.1(1) - 2 choices" and "D.8.1(6)".
0.5 Replace in the table with national choices “B.3.1(3)" with "B.3.1(2)".
0.5 Replace in the table with national choices "B.3.1(5) - 2 choices" with "B.3.1(5)".
4 Modification to Clause 1, “Scope”
1.1(2) Delete the word “other” in the first list item.
1.1(2) Add a new second list item: “preliminary design stage of buildings and civil engineering works with
heights up to 300 m;”
1.1(2) Add the following note below the list: “NOTE For wind profiles up to 300 m, see Annex A.”
5 Modification to Clause 3, “Terms, definitions and symbols”
3.2.2 Delete the word “natural” in the definition of the symbol n .
x
6 Modification to Clause 5, "Modelling of wind actions"
5.4(10) Modify the symbol “b” to “d” in Formula (5.1) and in the definition below the formula.
5.4(11) Replace the word “may” with “can” in the list items a) and b).
5.4(11) Delete “, they should be” in list item c).
7 Modification to Clause 6, "Wind velocity and velocity pressure”
6.2(7) Replace Note 1 with "NOTE 1 For a Gumbel distribution (see Annex L), the shape parameter K is equal
to β/α, where α is the corresponding location parameter and β is the corresponding scale parameter."
6.3.2(1) Delete the word “permanent” in Table 6.1.
6.3.2(1) Replace “x ” with “x” in Formula 6.8.
s
6.3.2(3) Replace “nominal angular sector” with “nominal direction” in the key to Figure 6.1.
6.3.2(3) Replace “2” with “x”, “3” with “2” and “4” with “3” in the key to Figure 6.1.
6.3.2(3) Replace Figure 6.1 with the following new Figure:

8 Modification to Annex A, “Terrain effects”
A.3(1) Add “and civil engineering works or forest,” between the words “buildings” and “and” in the
description of terrain category IV in Figure A.1.
A.4(10) Replace “3,5” with “5,0” in Formula (A.9).
A.4(10) Replace “log” with “log ” in Formula (A.10) to Formula (A.13).
A.4(11) Replace “it” with “the factor s ”.
o
A.4(11) Replace “s = A in Formula (A.5)” with “s = A given by Formula (A.6)”.
o
A.7.1(2) Replace “A.7.2 should be substituted for 6.3.2 and A.7.3 should be substituted for 6.4” with “6.3.2
should be substituted by A.7.2 and 6.4 should be substituted by A.7.3”.
9 Modification to Annex B, “Pressure coefficients for pressures on surfaces”
B.3.1(1) Delete “, which is the area of the surface,”.
B.3.1(1) Add “, c , c and“ between “coefficients” and “c ”.
pe1 pe10 peA
B.3.1(1) Add “in this Annex” in the end of the note which is numbered Note 1.
B.3.1(1) Add the following three new notes after the existing NOTE
“NOTE 2 External pressure coefficients given in this Annex are the most unfavourable values obtained in a
range of wind angles θ = ±45° either side of the relevant orthogonal direction, to be used unless the National Annex
gives different values to cover alternative ranges of wind angles.
NOTE 3 The procedures for effect of the size of the loaded area are as given in this Clause B.3, unless the National
Annex gives different procedures.
NOTE 4 The external global pressure coefficients and external local pressure coefficients can produce symmetric
load patterns. The asymmetry of the action on the vertical surfaces arising when θ ≠ 0° is covered by B.3.1(6). The
asymmetry of the action on the roof surfaces arising when θ ≠ 0° is accounted for by the large values of the pressure
coefficients in zone F in B.3.3 through B.3.6.”
Replace “NOTE” with “NOTE 1“.
B.3.1(2) Replace “should” with “may”, and add in the end of the paragraph (before the note): “, when the
total surface area contributing to the wind actions, is larger than A = 50 m .”.
B.3.1(2) Number the existing NOTE as NOTE 3, and add the following new notes beforehand:
“NOTE 1 External global pressure coefficients are given in Clause B.3, unless the National A
...