EN 1998-4:2025/prA1

Eurocode 8 - Design of structures for earthquake resistance - Part 4: Silos, tanks, pipelines, towers, masts and chimneys

EN 1998-4 is applicable to the seismic design of on-ground and elevated silos, on-ground, elevated and underground tanks, above-ground and buried pipeline systems, towers, masts and chimneys and ancillary elements attached to the aforementioned structures or in industrial facilities.

Eurocode 8 - Auslegung von Bauwerken gegen Erdbeben - Teil 4: Silos, Tankbauwerke und Rohrleitungen, Türme, Maste und Schornsteine

Eurocode 8 - Calcul des structures pour leur résistance au séisme - Partie 4 : Silos, réservoirs, tuyauteries, tours, mâts et cheminées

Evrokod 8 - Projektiranje potresnoodpornih konstrukcij - 4. del: Silosi, rezervoarji, cevovodi, stolpi, jambori in dimniki

EN 1998-4 se uporablja za potresno projektiranje silosov na tleh in dvignjenih silosov, rezervoarjev na tleh, dvignjenih in podzemnih rezervoarjev, nadzemnih in zakopanih cevovodnih sistemov, stolpov, jamborov in dimnikov ter pomožnih elementov, pritrjenih na prej omenjene strukture ali v industrijskih obratih.

General Information

• Status: Not Published
• Publication Date: 23-Apr-2028
• ICS: 91.010.30 - Technical aspects
• ICS: 91.060.40 - Chimneys, shafts, ducts
• ICS: 91.120.25 - Seismic and vibration protection
• Technical Committee: CEN/TC 250 - Structural Eurocodes
• Drafting Committee: CEN/TC 250/SC 8/WG 7 - Evolution of Eurocode 8
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 11-Jun-2026
• Due Date: 30-Nov-2026
• Completion Date: 11-Jun-2026
• Ref Project: SIST EN 1998-4:2025/oprA1:2026 - Eurocode 8 - Design of structures for earthquake resistance - Part 4: Silos, tanks, pipelines, towers, masts and chimneys

Relations

• Amends: EN 1998-4:2025 - Eurocode 8 - Design of structures for earthquake resistance - Part 4: Silos, tanks, pipelines, towers, masts and chimneys
• Effective Date: 07-Jan-2026

Overview

EN 1998-4:2025/prA1 represents a key draft amendment to the European standard Eurocode 8, specifically Part 4, focusing on the seismic design of silos, tanks, pipelines, towers, masts, and chimneys. Issued by CEN, this standard outlines comprehensive requirements for the earthquake-resistant design of structures commonly found in industrial facilities and infrastructure, including both elevated and on-ground installations, as well as buried and above-ground pipeline systems. The amendment updates and clarifies technical definitions, formulas, and design procedures to support structural safety and ensure consistency with other parts of Eurocode 8.

Key Topics

• Scope of Application: Covers seismic design for on-ground, elevated, and underground silos, tanks, pipelines (including buried pipeline systems), towers, masts, chimneys, and ancillary structural elements in industrial environments.
• Terminology and Symbols: Enhances clarity and consistency across definitions, units, and symbols related to seismic response and structural behavior, ensuring improved usability and integration with related Eurocode standards.
• Seismic Design Rules: Updates guidelines for anisotropic seismic effects, base shear calculations, modal mass participation, and dynamic structural response for silos, tanks, and pipelines.
• Soil-Structure Interaction: Maintains a strong focus on the influence of soil conditions and site effects, introducing updated procedures for considering spatial variability and site-specific seismic action effects in both above-ground and buried pipelines and tanks.
• Annex Updates: Includes corrections and detailed clarifications for annexes related to pressure functions, tables for the seismic design of tanks, and modeling of soil-structure interaction.
• Design at Fault Crossings: Provides updated requirements for pipelines crossing active seismic faults or zones with complex ground movement.

Applications

EN 1998-4:2025/prA1 is vital for:

• Industrial Facilities: Ensuring seismic resistance of tanks, silos, and pipelines in refineries, chemical plants, power plants, and storage facilities.
• Utilities and Infrastructure: Helping ensure the continuity of water supply, fuel, and other critical services through earthquake-resistant pipelines and tanks.
• Municipal and Regional Planning: Assisting engineers and planners to design and evaluate storage and distribution systems that comply with European seismic safety requirements, thereby minimizing risk to populations and the environment.
• Retrofit Projects: Guiding the assessment and strengthening of existing silos, tanks, and industrial chimneys to withstand seismic events.
• Civil Engineering Consultancies: Supporting best practices for seismic risk assessment, including the evaluation of local soil conditions, dynamic response, and resilient structural detailing.

The standard’s comprehensive coverage of both above-ground and underground facilities ensures robust design approaches for a wide range of structures exposed to seismic hazards, from urban infrastructure to remote industrial installations.

Related Standards

EN 1998-4:2025/prA1 operates alongside several closely linked standards that address both general and structure-specific requirements:

• EN 1998-1:2024 - Eurocode 8: General rules, seismic actions, and rules for buildings
• EN 1998-5:2024 - Eurocode 8: Foundations, retaining structures, and geotechnical aspects
• EN 1991-4:2026 - Actions on structures, including silos and tanks
• EN 1990-1:2023+A1:2026 - General basis of structural and geotechnical design
• EN 1993-1-6:2025 - Steel structures - Shell structures
• EN 1993-3 & EN 1993-4 series - Specific provisions for steel towers, tanks, and pipelines

Integrating EN 1998-4:2025/prA1 into seismic design strategies ensures compliance with the latest European practices and contributes to safer, more resilient industrial and utility structures under earthquake loading.

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Keywords: EN 1998-4, Eurocode 8, seismic design, earthquake resistance, silos, tanks, pipelines, towers, masts, chimneys, soil-structure interaction, CEN standards, infrastructure resilience.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2026
Evrokod 8 - Projektiranje potresnoodpornih konstrukcij - 4. del: Silosi, rezervoarji,
cevovodi, stolpi, jambori in dimniki
Eurocode 8 - Design of structures for earthquake resistance - Part 4: Silos, tanks,
pipelines, towers, masts and chimneys
Eurocode 8 - Auslegung von Bauwerken gegen Erdbeben - Teil 4: Silos, Tankbauwerke
und Rohrleitungen, Türme, Maste und Schornsteine
Eurocode 8 - Calcul des structures pour leur résistance au séisme - Partie 4 : Silos,
réservoirs, tuyauteries, tours, mâts et cheminées
Ta slovenski standard je istoveten z: EN 1998-4:2025/prA1
ICS:
91.010.30 Tehnični vidiki Technical aspects
91.060.40 Dimniki, jaški, kanali Chimneys, shafts, ducts
91.120.25 Zaščita pred potresi in Seismic and vibration
vibracijami protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
EN 1998-4:2025
NORME EUROPÉENNE
EUROPÄISCHE NORM
prA1
June 2026
ICS 91.060.40; 91.010.30; 91.120.25
English Version
Eurocode 8 - Design of structures for earthquake
resistance - Part 4: Silos, tanks, pipelines, towers, masts
and chimneys
Eurocode 8 - Calcul des structures pour leur résistance Eurocode 8 - Auslegung von Bauwerken gegen
au séisme - Partie 4 : Silos, réservoirs, tuyauteries, Erdbeben - Teil 4: Silos, Tankbauwerke und
tours, mâts et cheminées Rohrleitungen, Türme, Maste und Schornsteine
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 1998-4:2025. 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 1998-4:2025/prA1:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Modifications throughout the whole document . 4
2 Modification to the Introduction . 4
3 Modifications to Clause 2, “Normative references” . 4
4 Modifications to Clause 3, “Terms, definitions and symbols” . 4
5 Modifications to Clause 5, “Rules for silos” . 6
6 Modifications to Clause 6, “Rules for tanks” . 6
7 Modifications to Clause 7, “Rules for above-ground pipelines” . 9
8 Modifications to Clause 8, “Rules for buried pipelines” . 10
9 Modifications to Annex A, “Pressure functions and tables for the seismic design of tanks”10
10 Modifications to Annex B, “Soil-structure interaction effects for tanks” . 12
11 Modification to Annex D, “Modelling of soil-structure interaction for buried pipelines” . 12
12 Modification to Annex E, “Design differential surface displacement at pipeline – fault
crossing” . 12
13 Modifications to Annex G, “Masonry chimneys” . 13
14 Modifications to the Bibliography . 13
European foreword
This document (EN 1998-4:2025/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 1998-4:2025.
The following main changes to EN 1998-4:2025 are included in the amendment:
— clarification of terms, symbols and definitions for consistency in this document and with other
Eurocode 8 parts;
— clarification for the design of silos and correction of a formula;
— improvements and clarifications to the design of tanks with respect to support reactions and
pressures resulting from hydrodynamic and mass inertia effects, including completion of the
superposition rules;
— clarification of above-ground and buried pipeline design regarding the consideration of soil
conditions in the evaluation of seismic action effects;
— amendment of Annex A for the correction and clarification of pressure functions and tables for the
seismic design of tanks;
— amendment of Annex B and Annex D for the correction of variables;
— amendment of Annex E for the clarification of constructive rules.
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”
Replace “EN 1990” with “EN 1990-1”, except for 0.2 Introduction to replace “as defined in EN 1990” with
“as defined in EN 1990 (all parts)”
Replace “prEN 1991-4:2024” with “EN 1991-4:2026”
Replace “prEN 1998-1-2:2023” with “EN 1998-1-2:2026”
Replace “prEN 1993-3:2024” with “EN 1993-3:2026”
Replace “prEN 1993-4-1:2024” with “EN 1993-4-1:2026”
Replace “prEN 1993-4-2:2024” with “EN 1993-4-2:2026”
Replace “unit weight” with “weight density”
Replace “liquid weight” with “liquid weight density”
Replace “prestressed reinforced” with “prestressed”
Replace “Formulas” with “Formulae”
2 Modification to the Introduction
0.2 Replace “as defined in EN 1990” with “as defined in EN 1990 (all parts)”
3 Modifications to Clause 2, “Normative references”
Replace “EN 1990:2023, Eurocode — Basis of structural and geotechnical design” with
“EN 1990-1:2023+A1:2026, Eurocode — Basis of structural and geotechnical design — Part 1: New
structures”
Delete footnote “ As impacted by EN 1990:2023/prA1:2024.”
Delete two instances of “”
4 Modifications to Clause 3, “Terms, definitions and symbols”
3.2.1.1 Replace the definition of R with “radius of circular silo or silo compartment”
3.2.1.2 Delete “D diameter of circular tanks”
3.2.1.2 Replace the definition of R with “radius of circular tank”
' ' '
3.2.1.2 Replace “without” with “with” in the definitions of h , h and h
ir if c
3.2.1.2 Delete “pressure” in the definition of 𝛤𝛤c
3.2.1.2 Replace the definition of 𝛤𝛤 with “participation factor of the impulsive rigid mode in horizontal
ir,h
direction”
3.2.1.2 Replace the definition of 𝛤𝛤 with “participation factor of the impulsive rigid mode in vertical
ir,v
direction”
3.2.1.2 Replace the symbol and definition of ω with “ω circular frequency of the impulsive rigid
ir ir,h
mode for spherical tanks in horizontal direction”
3.2.1.4 Replace the definition of Δn with “Δn fault movement along the fault plane in case of normal-slip
fault”
3.2.1.4 Replace the definition of Δs with “Δs fault movement along the fault plane in case of strike-slip
fault”
3.2.1.7 Replace the definition of C with “ C dimensionless impulsive flexible pressure
b,if,h
b,,if h
function on the tank bottom for horizontal seismic actions”
3.2.1.7 Replace the definition of C with “ C dimensionless impulsive flexible pressure
b,if,v
b,,if v
function on the tank bottom for vertical seismic actions”
3.2.1.7 Replace the definition of C with “ dimensionless impulsive rigid pressure function
b,ir,h C
b,,ir h
on the tank bottom for horizontal seismic actions”
3.2.1.7 Replace the definition of C with “C dimensionless impulsive rigid base shear
F,ir,h F,ir,h
coefficient for horizontal seismic actions”
3.2.1.7 Replace the definition of C with “C dimensionless impulsive flexible base shear
F,if,h F,if,h
coefficient for horizontal seismic actions”
3.2.1.7 Replace the definition of C with “C dimensionless impulsive flexible base shear
F,if,v F,if,v
coefficient for vertical seismic actions”
3.2.1.7 Replace the definition of C with “ C dimensionless impulsive flexible pressure function on the
if,h
if,h
tank wall for horizontal seismic actions”
3.2.1.7 Replace the definition of C with “ C dimensionless impulsive flexible pressure function on the
if,v
if,v
tank wall for vertical seismic actions”
with “ dimensionless impulsive rigid pressure function on the
3.2.1.7 Replace the definition of Cir,h C
ir,h
tank wall for horizontal seismic actions”
3.2.1.7 Replace the definition of C with “ C convective overturning moment coefficient at the base
M,c
Mc,
plate”
3.2.1.7 Replace the definition of C with “ C impulsive flexible overturning moment coefficient
M,if,h
M,,if h
at the base plate for horizontal seismic actions”
3.2.1.7 Replace the definition of C with “ C impulsive rigid overturning moment coefficient at
M,ir,h
M,,ir h
the base plate for horizontal seismic actions”
3.2.1.7 Replace the definition of C with “ C convective overturning moment coefficient above
MW,c
MW,c
the base plate”
3.2.1.7 Replace the definition of C with “ C impulsive flexible overturning moment coefficient
MW,if,h
MW,,if h
above the base plate for horizontal seismic actions”
3.2.1.7 Replace the definition of C with “ C impulsive rigid overturning moment coefficient
MW,ir,h
MW,,ir h
above the base plate for horizontal seismic actions”
3.2.1.7 Delete “pressure” in the definition of 𝛤𝛤
c,n
5 Modifications to Clause 5, “Rules for silos”
5.3.1(4) Replace the clause to read as follows:
“Steel, reinforced concrete and prestressed concrete silos, with or without substructures, may be
analysed assuming linear elastic behaviour according to EN 1993-1-6:2025, 2.2, or to EN 1992-1-1,
respectively. If the steel silo shell is modelled, the modelling rules according to EN 1993-1-6:2025, 5.2,
should be applied.”
5.4.1(2) Add the following note after the definitions:
“NOTE The reduction factor λ accounts for an effective modal mass reduction lower than 20% in the 1st
fundamental mode compared to the mass of the silo and its contents. This factor considers the reduced activation
of the silo content due to friction at the silo bottom. This effect is more significant in squat silos. A value of 1,0 is a
conservative estimate.”
Formula (5.7) Replace the formula to read as follows:
“ (5.7)”
∆ =αγz min hd; / 2;3x / cosβ
( ) ( )
ph,so u b c
5.5.2.6(3) Replace “Installed anchors” with “Anchors”
6 Modifications to Clause 6, “Rules for tanks”
6.3.1(17) Replace the definition of T , T , T with “are the first natural periods of the impulsive rigid
ir,h if,h con
and impulsive flexible modes, in the horizontal direction, and of the convective vibration mode, as defined
in 6.4.1.4 for vertical cylindrical tanks and in 6.5.1.3 for vertical rectangular tanks”
6.3.1(17) Replace “6.4.1.5” with “6.4.1.4” in the definition of T , T
ir,v if,v
6.4.1.1.1(2) Replace “impulsive
...