EN 1998-1-1:2024/prA1

Eurocode 8 - Design of structures for earthquake resistance - Part 1-1: General rules and seismic action

1.1   Scope of EN 1998-1-1
(1)   This document is applicable to the design and verification of buildings and other structures for earthquake resistance. It gives general rules relevant to all types of structures, except for structures belonging to consequence classes CC0 or CC4.
NOTE   For further details on consequence class CC4, see 4.2.
(2)   This document provides basic performance requirements and compliance criteria applicable to buildings and other structures for earthquake resistance.
(3)   This document gives rules for the representation of seismic actions and the description of the design seismic situations.
NOTE   Certain types of structures, dealt with in other parts of Eurocode 8, need supplementary rules which are given in those relevant Parts.
(4)   This document contains general methods for structural analysis and verification under seismic actions, including base-isolated structures and structures with distributed dissipative systems.
(5)   This document contains rules for modelling and verification of ultimate strengths and deformations.
1.2   Assumptions
(1)   The assumptions of EN 1990 apply to this document.
(2)   It is assumed that no change in the structure and in the masses carried by the structure takes place during the construction phase or during the subsequent life of the structure with respect to the design unless proper justification and verification is provided. This applies also to ancillary elements (see 3.1.2). Due to the specific nature of seismic response, this applies even in the case of changes that lead to an increase of the structural resistance.
(3)   The design documents are assumed to indicate the geometry, the detailing, and the properties of the materials of all structural members. If appropriate, the design documents are also assumed to include the properties of special devices to be used and the distances between structural and ancillary elements. The necessary quality control provisions are assumed to be specified.
(4)   Members of special structural importance requiring special checking during construction are assumed to be identified in the design documents and the verification methods to be used are assumed to be specified.
(5)   It is assumed that in the case of high seismic action class (4.1.1(4)), formal quality system plans, covering design, construction, and use, additional to the control procedures prescribed in the other relevant Eurocodes, are specified.

Eurocode 8 - Auslegung von Bauwerken gegen Erdbeben - Teil 1-1: Grundlagen und Erdbebeneinwirkung

Eurocode 8 - Calcul des structures pour leur résistance au séisme - Partie 1-1 : Règles générales et actions sismiques

Evrokod 8 - Projektiranje potresnoodpornih konstrukcij - 1-1. del: Splošna pravila in potresni vpliv

1.1 Področje uporabe EN 1998-1-1
(1) Ta dokument se uporablja za projektiranje in preverjanje stavb in drugih konstrukcij za potresno odpornost. Podaja splošna pravila, ki so pomembna za vse vrste konstrukcij, razen za konstrukcije, ki spadajo v razred posledic CC0 ali CC4.
OPOMBA Za dodatne podrobnosti o razredu posledic CC4 glej 4.2.
(2) Ta dokument določa osnovne zahteve glede zmogljivosti in merila skladnosti, ki se uporabljajo za stavbe in druge konstrukcije za potresno odpornost.
(3) Ta dokument podaja pravila za predstavitev potresnih vplivov in opis projektnih potresnih situacij.
OPOMBA Določene vrste konstrukcij, obravnavane v drugih delih Eurokoda 8, potrebujejo dopolnilna pravila, ki so podana v teh ustreznih delih.
(4) Ta dokument vsebuje splošne metode za strukturno analizo in preverjanje pod potresnimi vplivi, vključno s konstrukcijami z osnovno izolacijo in konstrukcijami z razpršenimi disipativnimi sistemi.
(5) Ta dokument vsebuje pravila za modeliranje in preverjanje mejnih trdnosti in deformacij.
1.2 Predpostavke
(1) Predpostavke iz EN 1990 veljajo za ta dokument.
(2) Predpostavlja se, da med fazo gradnje ali med nadaljnjo življenjsko dobo konstrukcije ne pride do sprememb v strukturi in masah, ki jih nosi konstrukcija, glede na projekt, razen če so zagotovljene ustrezne utemeljitve in preveritve. To velja tudi za pomožne elemente (glej 3.1.2). Zaradi specifične narave potresnega odziva to velja tudi v primeru sprememb, ki vodijo do povečanja strukturne odpornosti.
(3) Predpostavlja se, da projektna dokumentacija navaja geometrijo, detajliranje in lastnosti materialov vseh strukturnih elementov. Če je primerno, se predpostavlja, da projektna dokumentacija vključuje tudi lastnosti posebnih naprav, ki se bodo uporabljale, in razdalje med strukturnimi in pomožnimi elementi. Predpostavlja se, da so določene potrebne določbe za nadzor kakovosti.
(4) Predpostavlja se, da so v projektni dokumentaciji identificirani elementi posebnega strukturnega pomena, ki zahtevajo posebno preverjanje med gradnjo, in da so določene metode preverjanja, ki se bodo uporabile.
(5) Predpostavlja se, da so v primeru visoke potresne akcijske klase (4.1.1(4)) določeni formalni načrti sistema kakovosti, ki zajemajo projektiranje, gradnjo in uporabo, poleg kontrolnih postopkov, predpisanih v drugih ustreznih Eurokodih.

General Information

• Status: Not Published
• Publication Date: 01-Aug-2027
• ICS: 91.010.30 - Technical aspects
• 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: 26-Mar-2026
• Due Date: 02-Mar-2026
• Completion Date: 26-Mar-2026
• Ref Project: SIST EN 1998-1-1:2024/oprA1:2026 - Eurocode 8 - Design of structures for earthquake resistance - Part 1-1: General rules and seismic action

Relations

• Amends: EN 1998-1-1:2024 - Eurocode 8 - Design of structures for earthquake resistance - Part 1-1: General rules and seismic action
• Effective Date: 30-Jul-2025

Overview

EN 1998-1-1:2024/prA1, titled Eurocode 8: Design of structures for earthquake resistance - Part 1-1: General rules and seismic action, is a draft amendment developed by CEN/TC 250 under the European Committee for Standardization (CEN). This standard is a part of the Eurocode suite, which provides harmonized technical rules for the structural design of buildings and civil engineering works across Europe.

EN 1998-1-1 sets out the general principles, criteria, and performance requirements for designing structures to resist seismic actions. Applicable to most buildings and structures (excluding those in consequence classes CC0 or CC4), it outlines procedures for modeling, analysis, and verification under earthquake loading to ensure safety and reliability throughout a structure’s lifecycle.

Key Topics

EN 1998-1-1:2024/prA1 addresses several essential aspects of earthquake-resistant design:

• Scope and Applicability:
  • Covers design and verification of buildings and other structures for earthquake resistance, with exceptions for certain consequence classes (notably CC0 and CC4).
• Performance Requirements:
  • Sets basic performance benchmarks and compliance criteria for seismic safety.
• Seismic Action Representation:
  • Details how to define and represent seismic actions in various design scenarios.
• Structural Analysis Methods:
  • Provides guidance on modeling and verification under seismic actions, including for base-isolated structures and those with energy dissipating systems.
• Deformation and Strength Verification:
  • Outlines processes for assessing ultimate strengths, deformations, and displacement-based design approaches.
• Seismic Design Situations:
  • Distinguishes between different seismic design situations and associated limit states (e.g., Near Collapse, Significant Damage, Damage Limitation, Fully Operational).
• Quality Control and Documentation:
  • Specifies assumptions on documentation, detailing, material properties, and identification of critical structural members requiring special verification during design and construction.
• Seismic Hazard and Site Conditions:
  • Addresses the influence of site-specific factors such as topography, amplification effects, and seismic hazard mapping.
• Antiseismic Devices:
  • Includes refined rules for the design and verification of structures equipped with seismic isolation and energy dissipation devices, with clarified definitions and reliability recommendations.

Applications

Who Should Use This Standard?

EN 1998-1-1:2024/prA1 is a critical reference for:

• Structural and civil engineers
• Architects designing in seismic zones
• Construction managers overseeing project compliance
• Regulators and code officials responsible for seismic safety

Practical Implementations

• New Construction:
  • Ensures that new buildings and infrastructure are designed for adequate seismic resistance according to unified European parameters.
• Retrofit and Upgrade:
  • Provides criteria for the assessment and strengthening of existing structures subject to seismic risk.
• Quality Assurance in Construction:
  • Sets standards for documentation, detailing, and control throughout the design, construction, and operational phases.

Seismic Design Scenarios

• Application of displacement-based and force-based design approaches
• Selection and scaling of seismic input motions
• Design of critical connections, joints, and lifelines crossing seismic joints
• Criteria for lifespan reliability indices and target probabilities of exceedance for different consequence classes

Related Standards

For comprehensive seismic design, EN 1998-1-1 should be used in conjunction with related Eurocode documents and standards, such as:

• EN 1990-1: Basis of structural and geotechnical design
• EN 1998-2: Bridges - Seismic design of bridges
• EN 1998-3: Assessment and retrofitting of buildings
• EN 1992-4/EN 1994-1-1: Material-specific requirements (concrete and steel structures)
• Annexes of EN 1998-1-1: Including seismic hazard maps, input motions, reliability, and fastening to concrete

Additional alignment with local national annexes and country-specific requirements may also be necessary. By keeping abreast of these evolving standards, engineers and designers can ensure their projects meet leading-edge European seismic safety requirements.

Keywords: Eurocode 8, EN 1998-1-1, earthquake resistance, seismic design, structural engineering, building codes, seismic action, anti-seismic devices, structural analysis, performance requirements, seismic standards, CEN, European standard, seismic hazard, site conditions, reliability index.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2026
Evrokod 8 - Projektiranje potresnoodpornih konstrukcij - 1-1. del: Splošna pravila
in potresni vpliv
Eurocode 8 - Design of structures for earthquake resistance - Part 1-1: General rules
and seismic action
Eurocode 8 - Auslegung von Bauwerken gegen Erdbeben - Teil 1-1: Grundlagen und
Erdbebeneinwirkung
Eurocode 8 - Calcul des structures pour leur résistance au séisme - Partie 1-1 : Règles
générales et actions sismiques
Ta slovenski standard je istoveten z: EN 1998-1-1:2024/prA1
ICS:
91.010.30 Tehnični vidiki Technical aspects
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 1998-1-1:2024
NORME EUROPÉENNE
EUROPÄISCHE NORM
prA1
March 2026
ICS 91.010.30; 91.120.25
English Version
Eurocode 8 - Design of structures for earthquake
resistance - Part 1-1: General rules and seismic action
Eurocode 8 - Calcul des structures pour leur résistance Eurocode 8 - Auslegung von Bauwerken gegen
au séisme - Partie 1-1 : Règles générales et actions Erdbeben - Teil 1-1: Grundlagen und
sismiques Erdbebeneinwirkung
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 1998-1-1:2024. 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 1998-1-1:2024/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 Modification to 3.1, “Terms and definitions” . 4
4 Modification to Clause 4, “Basis of design” . 6
5 Modification to Clause 5, “Site conditions and seismic action” . 6
6 Modification to Clause 6, “Modelling, analysis, and verification” . 6
7 Modification to Clause 7, “Deformation criteria for displacement-based approach” 10
8 Modification to Annex A, “European seismic hazard maps” . 13
9 Modification to Annex D, “Criteria for selection and scaling of input motions” . 13
10 Modification to Annex E, “Determination of target displacement and limit-state
spectral acceleration by using non-linear response-history analyses of an equivalent
SDOF model” . 13
11 Modification to Annex F, “Target reliability and simplified reliability-based
verification format” . 14
12 Modification to Annex G, “Design of fastenings to concrete in the seismic design
situation” . 15
European foreword
This document (EN 1998-1-1:2024/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 1998-1-1:2024 and is currently submitted to the CEN Enquiry.
The following main changes to EN 1998-1-1:2024 are included in the amendment:
— clarification of terms, symbols and definitions for consistency in this document and with other
Eurocode 8 parts;
— clarification of expected performance for the use of antiseismic devices and precision on the
amplification factor γ for the design of isolators and energy dissipation devices;
x
— improvements and clarifications on resistance criteria for displacement-based approach;
— amendment of Annex F in order to avoid possible inconsistencies, with elimination of one NDP.
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”.
Replace “EN 1998-1-2:— ” with “EN 1998-1-2:2026”.
Replace “EN 1998-2:— ” with “EN 1998-2:2025”.
Replace “EN 1998-3:— ” with “EN 1998-3:2025”.
Replace “EN 1994-1-1:— ” with “EN 1994-1-1:2025”.
Replace “EN 1992-4:2018” with “prEN 1992-4:2025”.
Replace “5 % damping)” with “5 % damping ratio)”.
Replace “anti-seismic” with “antiseismic”.
Rename Annex H as Annex M and correct all references to its content accordingly.
2 Modification to the Introduction
In 0.2, replace “EN 1998-2 Eurocode 8 — Design of structures for earthquake resistance — Part 1-2:
Bridges” with “EN 1998-2 Eurocode 8 — Design of structures for earthquake resistance — Part 2:
Bridges”.
In 0.5, replace “F.3(1) – 2 choices” with “F.3(1)”.
3 Modification to Clause 3, “Terms, definitions and symbols”
Add the following definition as 3.1.6 and renumber subsequent definitions:
“damping ratio
ratio of the equivalent viscous damping of an oscillator or a mode to critical damping”.
Add the following definition as 3.1.8 and renumber subsequent definitions:
“design seismic action
seismic action in each Seismic Design Situation, considering the hazard and site conditions and the
Consequence Class of the structure
Note 1 to entry: The design value of the seismic action AEd,ULS depends on the Ultimate Limit State under
consideration: Near Collapse (NC) or Significant Damage (SD).
Note 2 to entry: The design value of the seismic action AEd,SLS depends on the Serviceability Limit State under
consideration: Damage Limitation (DL) or Fully Operational (OP).”.
Add the following definition as 3.1.29 and renumber subsequent definitions:
“predominant mode (in each direction)
mode of vibration corresponding to the largest value of the effective modal mass in that direction”.
Replace the current definition of “3.1.33 seismic action class” with:
“seismic action classes
classes used to establish the applicability of simplified methods and ductility classes, associated to
intervals of the seismic action index”.
Replace the current definition of “3.1.34 seismic action index” to read as follows:
“seismic action index
index used to define seismic action classes, based on seismic hazard, site amplification due to both
topography and site category, and consequence class”.
Add the following definition as 3.1.38 and renumber subsequent definitions:
“seismic design situations
exceptional conditions during a seismic event associated to performance objectives expressed in terms
of Limit States
Note 1 to entry: A Design Seismic Action is associated to each Seismic Design Situation considered.”.
In 3.2.1.3, replace “reduced design spectrum” with “reduced spectrum” in the definitions of R (T), S (T),
q r
S (T) and β.
vr
In 3.2.1.3, replace the definition of δ with “Value of the local deformation associated to a plastic
NC
mechanism that corresponds to the attainment of NC limit state”.
In 3.2.1.3, delete “δ Deformation parameter associated to a plastic mechanism in state s”.
s
In 3.2.1.3, replace the definition of δ with “Value of the local deformation associated to a plastic
SD
mechanism that corresponds to the attainment of SD limit state”.
In 3.2.1.3, replace the definition of δ with “Ultimate local deformation capacity of the member in the
u
ductile post-elastic mechanism”.
pl
In 3.2.1.3, replace the definition of δ with “Plastic part of the ultimate local deformation capacity of the
u
member in the ductile post-elastic mechanism”.
In 3.2.1.3, replace the definition of δ with “Local deformation of the member at yielding”.
y
In 3.2.1.4, replace the definition of A with “Area of the concrete section or cross-sectional area of a steel
c
column”.
In 3.2.1.4, replace the definition of n with “Shear deformation contribution factor for steel members”.
In 3.2.1.4, add the following definition: “θ Ultimate chord rotation capacity of a member”.
u
pl
In 3.2.1.4, add the following definition: “θ Plastic part of the ultimate chord rotation capacity of a
u
member”.
In 3.2.1.4, add the following definition: “θ Chord rotation of a member at yielding”.
y
In 3.2.1.5, add the following definition: “E PMT modulus of deformation” in Upper case Latin symbols.
m
In 3.2.1.5, add the following definition: “N SPT blow count normalised for the energy ratio” in Upper
case Latin symbols.
In 3.2.1.5, add the following definition: “c Undrained shear strength of soil from FVT or lab tests” in
u
Lower case Latin symbols.
In 3.2.1.5, add the following definition: “p PMT limit pressure” in Lower case Latin symbols.
lim
In 3.2.1.5, add the following definition: “q CPT cone tip resistance” in Lower case Latin symbols.
c
In 3.2.1.5, add the following definition: “v Equivalent shear wave velocity down to a depth 10 m ≤ z
s,z d
≤ 30 m” in Lower case Latin symbols.
In 3.2.1.7, replace the symbol and definition of P(LS|S ) with “P(LS|S ) Probability that the ground motion
e e
with intensity equal to S will cause the exceedance of a designated limit state”.
e
In 3.2.1.7, replace the symbol and definition of S with “S Spectral acceleration at the predominant
e e
period of the structure, i.e. S (T )”.
e 1
In 3.2.1.7, replace the definition of S with “Limit-state spectral acceleration, i.e. the median value of
e,LS
spectral acceleration at the predominant vibration period of the structure which causes a designated limit
state” and move all symbols starting with S to after the symbols starting with P.
4 Modification to Clause 4, “Basis of design”
In 4.1(2), replace “under prescribed seismic actions” with “under design seismic actions”.
In 4.1(4) replace “seismic design cases” with “design seismic actions”.
In 4.1(6), NOTE, replace “in the National Annex” with “in the National Annexes of the relevant parts of
Eurocode 8”.
In 4.1(7), NOTE, replace “This excludes the use of this option for structures not explicitly mentioned in the
corresponding parts” with “Structures which are not explicitly associated with this clause in the relevant
parts of Eurocode 8 are excluded from the use of this option”.
5 Modification to Clause 5, “Site conditions and seismic action”
In Table 5.5, delete the 2nd row and replace the title of the table with “Topography amplification factors
for ground types A and B with simple topographic irregularities of height greater than 30 m and average
slope angles larger than 15°”.
In Table 5.5, 4th row, 1st column, replace “Ridges with width at the top much smaller than at the base”
with “Ridges with width at the top smaller than 200 m”.
In Table 5.5, 5th row, 1st column, replace “Ridges with width at the top much smaller than at the base”
with “Ridges with width at the top smaller than 200 m”.
In Table 5.5, 6th row, replace “A linear decrease of F is considered between point T and point B (base)
T
and point A (located at 100 m distance from T), where F = 1 applies.” with “A linear decrease of F is
T T
considered between point T and point B (base), as well as between point T and point A (located at 100 m
= 1 applies. In ridges with width at the top smaller than 200 m, the topographic
distance from T), where FT
amplification factor decreases linearly up to the mid-point of the ridge using a reference distance of
100 m to reach a value of 1.”.
In 5.2.2.2(8), delete “ for design”.
In the title of 5.2.2.4, Replace “Design peak values” with “Peak values”.
In 5.2.2.4(1), replace “Design peak values” with “Peak values”.
In 5.2.3.2(3), replace the definition of a with “is given by Formula (5.30), with L in m”.
kl g
6 Modification to Clause 6, “Modelling, analysis, and verification”
In 6.1(1), replace “prescribed seismic action” with “design seismic action”.
In 6.1(9), replace “prescribed seismic action” with “design seismic action”.
In 6.2.1(1), add the following note “NOTE 2 Eigenmode analysis and the “Ritz modes” method are
possible ways to determine the modes of vibration of the structure.” and rename the current NOTE into
NOTE 1.
In 6.2.1(3), replace “where the combination coefficients” with “where “+” means “to be combined with”
and the combination coefficients”.
In the title of 6.3, replace “Seismic action” with “Design seismic action”.
In 6.3(1), replace “seismic action” with “design seismic action”.
In 6.3(2), replace “seismic action” with “design seismic action”.
In 6.3(3), replace “5.2.2.2 and 5.2.2.3” with “5.2.2.2 to 5.2.2.4” and replace “seismic action” with “design
seismic action”.
In 6.4.1(1), replace “seismic action” with “design seismic action”.
In 6.4.2(1), add the following note “NOTE 2 The predominant mode of vibration in a given direction is
the mode corresponding to the largest value of the effective modal mass in that direction.” and rename
the current NOTE into NOTE 1.
In 6.4.2(2), replace “induced by the seismic action” with “induced by the design seismic action”.
In 6.4.2(2), delete “, but not larger than 3q” in the definition of q .
disp
In 6.4.2(3), replace “seismic action” with “design seismic action”.
In 6.4.3.2(1), delete “ (with T ≤ T )”.
j i
In 6.4.4(1), replace “seismic action” with “design seismic action”.
In 6.4.4(2), replace “unfavorable” with “unfavourable” and replace the 3 instances of “seismic action” with
“design seismic action”.
...