EN 1991-1-7:2025
(Main)Eurocode 1 - Actions on structures - Part 1-7: Accidental actions
Eurocode 1 - Actions on structures - Part 1-7: Accidental actions
(1) EN 1991-1-7 provides actions and rules for safeguarding buildings and civil engineering works against identifiable accidental actions.
NOTE 1 Identifiable accidental actions include impact from vehicles and internal explosions.
NOTE 2 Rules on impact from vehicles travelling on a bridge deck are given in EN 1991-2.
(2) EN 1991-1-7 also covers: actions and rules for tying systems and key members; information on risk assessment; dynamic design for impact; actions for internal explosions; actions from debris.
(3) Actions from ship operations such as berthing and mooring are outside the scope of this document.
(4) Actions due to high explosives that detonate are outside the scope of this document.
Eurocode 1 - Einwirkungen auf Tragwerke - Teil 1-7: Außergewöhnliche Einwirkungen
1.1 Anwendungsbereich von prEN 1991 1 7
(1) prEN 1991 1 7 enthält Einwirkungen und Regelungen für die Sicherung von Hochbauten und anderen Ingenieurbauwerken gegen identifizierbare außergewöhnliche Einwirkungen.
ANMERKUNG 1 Identifizierbare außergewöhnliche Einwirkungen umfassen Anpralllasten durch Fahrzeuge und Innenraumexplosionen.
ANMERKUNG 2 Regelungen für Anpralllasten durch Fahrzeuge auf einem Brückenüberbau sind in EN 1991 2 angegeben.
(2) prEN 1991 1 7 behandelt außerdem Einwirkungen und Regelungen für Zugverankerungssysteme und Haupttragelemente; Informationen zur Risikobeurteilung; dynamische Anprallberechnungen; Einwirkungen durch Innenraumexplosionen; Einwirkungen aus Trümmern.
1.2 Annahmen
(1) Für prEN 1991 1 7 gelten die allgemeinen Annahmen von EN 1990.
(2) prEN 1991 1 7 ist dafür vorgesehen, zusammen mit EN 1990, EN 1991 (alle Teile) und den anderen Eurocode-Teilen für die Bemessung und Konstruktion von Tragwerken angewendet zu werden.
Eurocode 1 - Actions sur les structures - Partie 1-7: Actions accidentelles
1.1 Domaine d'application du prEN 1991-1-7
(1) Le prEN 1991 1 7 fournit des actions et des règles pour préserver les bâtiments et autres ouvrages de génie civil contre les actions accidentelles identifiables.
NOTE 1 Les actions accidentelles identifiables incluent les chocs produits par des véhicules et des explosions intérieures.
NOTE 2 Les règles relatives aux chocs produits par des véhicules circulant sur un tablier de pont sont données dans le prEN 1991 2.
(2) Le prEN 1991 1 7 spécifie également des actions et des règles pour les tirants et les éléments clefs ; des informations sur l'évaluation des risques ; le calcul dynamique pour le choc ; des actions pour les explosions intérieures ; des actions dues aux débris.
1.2 Hypothèses
(1) Les hypothèses générales de l'EN 1990 s'appliquent au prEN 1991 1 7.
(2) Le prEN 1991 1 7 est destiné à être utilisé avec l'EN 1990, l'EN 1991 (toutes les parties) et les autres parties de l'Eurocode pour le calcul des structures.
Evrokod 1 - Vplivi na konstrukcije -1-7. del: Nezgodni vplivi
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN 1991-1-7:2023
01-december-2023
Nadomešča:
SIST EN 1991-1-7:2006
Evrokod 1: Vplivi na konstrukcije -1-7. del: Nezgodni vplivi
Eurocode 1 - Actions on structures - Part 1-7: Accidental actions
Eurocode 1 - Einwirkungen auf Tragwerke - Teil 1-7: Außergewöhnliche Einwirkungen
Eurocode 1 - Actions sur les structures - Partie 1-7: Actions accidentelles
Ta slovenski standard je istoveten z: prEN 1991-1-7
ICS:
91.010.30 Tehnični vidiki Technical aspects
oSIST prEN 1991-1-7:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
oSIST prEN 1991-1-7:2023
oSIST prEN 1991-1-7:2023
DRAFT
EUROPEAN STANDARD
prEN 1991-1-7
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2023
ICS 91.010.30
English Version
Eurocode 1 - Actions on structures - Part 1-7: Accidental
actions
Eurocode 1 - Actions sur les structures - Partie 1-7: Eurocode 1 - Einwirkungen auf Tragwerke - Teil 1-7:
Actions accidentelles Außergewöhnliche Einwirkungen
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 250.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard 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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1991-1-7:2023 E
worldwide for CEN national Members.
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Contents Page
European foreword . 4
0 Introduction . 5
1 Scope . 8
1.1 Scope of prEN 1991-1-7 . 8
1.2 Assumptions . 8
2 Normative references . 8
3 Terms, definitions and symbols . 8
3.1 Terms and definitions . 8
3.2 Symbols . 12
4 Basis of design . 13
4.1 General strategies . 13
4.2 Accidental design situations — strategies for identified accidental actions . 13
4.3 Accidental design situations — use of consequence classes . 14
5 Impact . 16
5.1 Field of application . 16
5.2 Classification of actions . 17
5.3 Representation of actions . 17
5.4 Accidental actions caused by road vehicles . 17
5.5 Accidental actions caused by forklift trucks . 21
5.6 Accidental actions caused by derailed rail traffic under or adjacent to structures . 21
5.7 Accidental actions caused by ship traffic . 24
5.8 Accidental actions caused by helicopters . 27
6 Internal explosions . 28
6.1 Field of application . 28
6.2 Representation of action . 28
6.3 Principles for design . 29
Annex A (informative) Actions for tying systems and key members . 31
A.1 Use of this Annex . 31
A.2 Scope and field of application . 31
A.3 Horizontal ties . 31
A.4 Vertical ties . 34
A.5 Key members . 34
Annex B (informative) Information on risk assessment . 35
B.1 Use of this annex . 35
B.2 Scope and field of application . 35
B.3 Description of scope, assumptions and limitations of a risk analysis . 35
B.4 Methods of risk analysis . 36
B.5 Risk evaluation and acceptance . 37
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B.6 Risk mitigating measures . 39
B.7 Reconsideration . 39
B.8 Communication of results and conclusions . 39
B.9 Applications to buildings and civil engineering structures . 39
Annex C (informative) Dynamic design for impact . 47
C.1 Use of this annex . 47
C.2 Scope and field of application . 47
C.3 General . 47
C.4 Impact dynamics . 48
C.5 Impact from aberrant road vehicles . 49
C.6 Impact by ships . 52
Annex D (informative) Internal explosions. 56
D.1 Use of this annex . 56
D.2 Scope and field of application . 56
D.3 General . 56
D.4 Natural gas explosions . 56
D.5 Dust explosions in rooms, vessels and bunkers . 57
D.6 Explosions in road and rail tunnels . 59
D.7 Dust, gas and vapour/air explosions in energy ducts . 60
Annex E (informative) Actions from debris . 64
E.1 Use of this annex . 64
E.2 Scope and field of application . 64
E.3 Actions from debris . 64
Bibliography . 66
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European foreword
This document (prEN 1991-1-7:2023) 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 1991-1-7:2006.
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.
In comparison with the previous edition, the following technical modifications have been made:
a) Transferring design strategies for robustness and related rules to EN 1990;
b) providing consistency between text and technical information on impact;
c) limiting the scope of Annex A to rules and actions for tying systems and key members; and
d) inserting technical clarifications in Annex C.
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0 Introduction
0.1 Introduction to the Eurocodes
The structural Eurocodes comprise the following standards generally consisting of a number of Parts:
— 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 structure
— 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
— New parts are under development, e.g. Eurocode for design of structural glass
The Eurocodes are intended for use by designers, clients, manufacturers, constructors, relevant
authorities (in exercising their duties in accordance with national or international regulations),
educators, software developers, and committees drafting standards for related product, testing and
execution standards.
NOTE Some aspects of design are most appropriately specified by relevant authorities or, where not specified,
can be agreed on a project-specific basis between relevant parties such as designers and clients. The Eurocodes
identify such aspects making explicit reference to relevant authorities and relevant parties.
0.2 Introduction to EN 1991 (all parts)
(1) EN 1991 (all parts) specifies actions for the structural and geotechnical design of buildings, bridges
and other civil engineering works, including temporary structures, in conjunction with EN 1990 and the
other Eurocodes.
(2) EN 1991 (all parts) does not cover seismic design. Provisions for structures in seismic regions are
given in EN 1998.
(3) EN 1991 (all parts) is also applicable to existing structures for:
— structural assessment,
— strengthening or repair,
— change of use.
NOTE In these cases, additional or amended provisions are necessary.
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(4) EN 1991 (all parts) is also applicable for the design of structures where materials or actions outside
the scope of the other Eurocodes are involved.
NOTE In this case, additional or amended provisions are necessary.
(5) EN 1991 is subdivided in various parts:
EN 1991-1-1, Eurocode 1 — Actions on structures — Part 1-1: Specific weight of materials, self-weight of
construction works and imposed loads for buildings
EN 1991-1-2, Eurocode 1 — Actions on structures — Part 1-2: Actions on structures exposed to fire
EN 1991-1-3, Eurocode 1 — Actions on structures — Part 1-3: Snow Loads
EN 1991-1-4, Eurocode 1 — Actions on structures — Part 1-4: Wind Actions
EN 1991-1-5, Eurocode 1 — Actions on structures — Part 1-5: Thermal Actions
EN 1991-1-6, Eurocode 1 — Actions on structures — Part 1-6: Actions during execution
EN 1991-1-7, Eurocode 1 — Actions on structures — Part 1-7: Accidental actions
EN 1991-1-8, Eurocode 1 — Actions on structures — Part 1-8: Actions from waves and currents on coastal
structures
EN 1991-1-9, Eurocode 1 — Actions on structures — Part 1-9: Atmospheric icing
EN 1991-2, Eurocode 1 — Actions on structures — Part 2: Traffic loads on bridges and other civil
engineering works
EN 1991-3, Eurocode 1 — Actions on structures — Part 3: Actions induced by cranes and machines
EN 1991-4, Eurocode 1 — Actions on structures — Part 4: Silos and tanks
0.3 Introduction to prEN 1991-1-7
prEN 1991-1-7 describes principles and application rules for the determination of accidental actions on
buildings and other civil engineering works. The following actions are included:
— impact forces from vehicles, rail traffic, ships and helicopters;
— actions due to internal explosions of combustible gases and dust as well as of vapour-air-mixture;
and
— actions for tying systems and key members.
NOTE Other Eurocodes can cover specific accidental actions.
0.4 Verbal forms used in the Eurocodes
The verb “shall” expresses a requirement strictly to be followed and from which no deviation is permitted
in order to comply with the Eurocodes.
The verb “should” expresses a highly recommended choice or course of action. Subject to national
regulation and/or any relevant contractual provisions, alternative approaches could be used/adopted
where technically justified.
The verb “may” expresses a course of action permissible within the limits of the Eurocodes.
The verb “can” expresses possibility and capability; it is used for statements of fact and clarification of
concepts.
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0.5 National Annex for prEN 1991-1-7
National choice is allowed in this standard where explicitly stated within notes. National choice includes
the selection of values for Nationally Determined Parameters (NDPs).
The national standard implementing prEN 1991-1-7 can have a National Annex containing all national
choices to be used for the design of buildings and civil engineering works to be constructed in the relevant
country.
When no national choice is given, the default choice given in this standard is to be used.
When no national choice is made and no default is given in this standard, the choice can be specified by a
relevant authority or, where not specified, agreed for a specific project by appropriate parties.
The National choice is allowed in prEN 1991-1-7 through the following clauses:
4.1(2) 4.2(1) 4.3(1) – 2 choices 4.3(2)
5.1(1) – 2 choices 5.2(2) 5.3(3) 5.4.1(1) – 3 choices
5.4.1(2) – 2 choices 5.4.1(3) 5.4.2(2) – 2 choices 5.4.2(3)
5.4.2(5) 5.5(2) 5.6.1(1) 5.6.2.2(1) – 2 choices
5.6.2.3(1) 5.6.2.4(1) 5.6.2.4(2) 5.6.2.4(3)
5.6.2.4(4) 5.6.2.4(5) 5.6.2.4(6) 5.6.2.5(1)
5.6.3(1) 5.6.3(3) 5.7.1(3) 5.7.1(5)
5.7.2(1) 5.7.2(2) – 2 choices 5.7.2(5) 5.7.2(6)
5.7.2(7) – 2 choices 5.7.3(1) 5.7.3(2) 5.7.3(3)
5.7.3(4) 5.7.3(5) – 2 choices 5.7.3(6) – 2 choices 5.8(2)
6.3.1(1) A.1(1) A.3.1(4) A.3.2(3)
A.3.2(4) A.3.3(1) A.4.3(1) – 2 choices A.5(1)
B.1(1) C.1(1) D.1(1) D.6(3)
E.1(1)
National choice is allowed in prEN 1991-1-7 on the application of the following informative annexes:
Annex A Annex B Annex C Annex D
The National Annex can contain, directly or by reference, non-contradictory complementary information
(NCCI) for ease of implementation, provided it does not alter any provisions of the Eurocodes.
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1 Scope
1.1 Scope of prEN 1991-1-7
(1) prEN 1991-1-7 provides actions and rules for safeguarding buildings and other civil engineering
works against identifiable accidental actions.
NOTE 1 Identifiable accidental actions include impact from vehicles and internal explosions.
NOTE 2 Rules on impact from vehicles travelling on a bridge deck are given in prEN 1991-2.
(2) prEN 1991-1-7 also covers actions and rules for tying systems and key members; information on risk
assessment; dynamic design for impact; actions for internal explosions; actions from debris.
1.2 Assumptions
(1) The general assumptions of EN 1990 apply to prEN 1991-1-7.
(2) prEN 1991-1-7 is intended to be used in conjunction with EN 1990, EN 1991 (all parts) and the other
Eurocode parts for the design of structures.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
NOTE See the Bibliography for a list of other documents cited that are not normative references, including
those referenced as recommendations (i.e. in “should” clauses), permissions (“may” clauses), possibilities (“can”
clauses), and in notes.
EN 1990:2023, Eurocode — Basis of structural and geotechnical design
EN 1991 (all parts), Eurocode 1 — Actions on structures
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in EN 1990 and the following terms,
definitions and symbols apply.
NOTE Other specific symbols, especially treated in informative annexes, are given within the text.
3.1 Terms and definitions
3.1.1 General terms relevant to accidental actions
3.1.1.1
burning velocity
velocity of flame propagation relative to that of the unburned dust, gas or vapour that is ahead of the
flame front
3.1.1.2
consequence class
categorization of the consequences of structural failure in terms of loss of human lives or personal injury
and of economic, social, or environmental losses
[SOURCE: EN 1990:2023, 3.1.2.33]
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3.1.1.3
deflagration
propagation of a combustion zone at a velocity that is less than the speed of sound in the unreacted
medium
3.1.1.4
detonation
propagation of a combustion zone at a velocity that is greater than the speed of sound in the unreacted
medium
3.1.1.5
dynamic force
force that varies in time and which has the potential to cause significant dynamic effects on the structure;
in the case of impact, the dynamic force represents the force with an associated contact area at the point
of impact (see Figure 1.1)
Key
a equivalent static force
b dynamic force
c structural response
Figure 1.1 — Dynamic force
3.1.1.6
equivalent static force
alternative representation for a dynamic force including the dynamic response of the structure (see
Figure 1.1)
3.1.1.7
flame speed
speed of a flame front relative to a fixed reference point
3.1.1.8
flammable limit
minimum or maximum concentration of a combustible material in a homogeneous mixture with a
gaseous oxidizer that will propagate a flame
3.1.1.9
impacting object
object impacting upon a structure (e.g. vehicle, ship, etc.) during an accidental action
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3.1.1.10
key member
structural member upon which the stability of the remainder of the structure depends
3.1.1.11
load-bearing wall construction
non-framed masonry cross-wall construction mainly supporting vertical loading, including lightweight
panel construction comprising timber or steel vertical studs at close centres with particle board,
expanded metal or alternative sheathing
3.1.1.12
localized failure
part of a structure that is assumed to have collapsed, or been severely disabled, by an event
3.1.1.13
risk
measure of the combination (usually the product) of the probability or frequency of occurrence of a
defined hazard and the magnitude of the consequences of the occurrence
3.1.1.14
robustness
ability of a structure to withstand events like impact, explosions, fire or the consequences of human error,
without being damaged to an extent disproportionate to the original cause
3.1.1.15
substructure
part of a building structure that supports the superstructure
Note 1 to entry: In the case of buildings, this usually relates to the foundations and other construction work below
ground level. In the case of bridges, this usually relates to foundations, abutments, piers and columns, etc.
3.1.1.16
superstructure
part of a building structure that is supported by the substructure
Note 1 to entry: In the case of buildings this usually relates to the above ground construction. In the case of bridges
this usually relates to the bridge deck.
3.1.1.17
venting panel
non-structural part of the enclosure (wall, floor, ceiling) with limited resistance that is intended to relieve
the developing pressure from deflagration in order to reduce pressure on structural parts of the building
3.1.1.18
explosion
rapid chemical reaction of dust, gas or vapour in the air, leading to high temperatures and high
overpressures, and whose pressures propagate as waves
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3.1.2 Specific terms relevant to Annex B
3.1.2.1
consequence
possible result of an (in risk analysis usually unwanted) event
Note 1 to entry: Consequences can be verbally or numerically expressed in terms of loss of life, injury, economic
loss, environmental damage, disruption to users and the public, etc. Both immediate consequences and those that
arise after a certain time has elapsed are to be included.
3.1.2.2
hazard scenario
critical situation at a particular time consisting of a leading hazard together with one or more
accompanying conditions which leads to an unwanted event (e.g. complete collapse of the structure)
3.1.2.4
risk acceptance criteria
acceptable limits for probabilities of certain consequences of an undesired event, expressed in terms of
annual frequencies
Note 1 to entry: These criteria are normally determined at national level to reflect the level of risk considered to be
acceptable to people and society.
3.1.2.5
risk analysis
systematic approach for describing and/or calculating risk
Note 1 to entry: Risk analysis involves the identification of undesired events, and the causes, likelihoods and
consequences of these events.
3.1.2.6
risk evaluation
comparison of the results of a risk analysis with the acceptance criteria for risk and other decision criteria
3.1.2.7
risk management
systematic measures undertaken by an organization in order to attain and maintain a level of safety that
complies with defined objectives
3.1.2.8
undesired event
event or condition that can cause loss of life, injury, economic loss, environmental damage, disruption to
users and the public, etc.
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3.2 Symbols
3.2.1 Latin upper-case letters
C force term for helicopter impact
F collision force
F horizontal equivalent static or dynamic design force (frontal force, usually in the
dx
direction of the normal travel)
F horizontal equivalent static or dynamic design force (lateral force, usually
dy
perpendicular to the direction of the normal travel)
Fmax maximum pressure developed in a contained deflagration of an optimum mixture
FR frictional impact force
W sum of the net weight and hoisting load of a loaded forklift truck
3.2.2 Latin lower-case letters
a height of the application area of a collision force
b width of the application area of a collision force
b width of bridge pier
Pier
d distance from the structural member to the centre line of the road or track
h height of (resulting) collision force
h clearance between the road surface and the underside of the bridge deck, below which
an impact on the superstructure needs to be taken into account without any reduction
h clearance between the road surface and the underside of the bridge deck, above which
no impact needs to be considered
ℓ ship length
r reduction factor
F
s distance from structural member to the point where the vehicle leaves the trafficked
lane
m mass
x direction of (normal) travel or track
y direction perpendicular of (normal) travel or track
v velocity (i.e. v is an initial moving velocity)
3.2.3 Greek lower-case letters
α inclination angle
Δh difference between h and h
1 0
μ friction coefficient
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4 Basis of design
4.1 General strategies
(1) Structures shall be designed for the relevant accidental design situations in accordance with
EN 1990:2023, 5.2(3).
NOTE The strategies to be considered for accidental design situations are illustrated in Table 4.1, which is
identical to Table E.1 of EN 1990:2023.
Table 4.1 — Strategies for Accidental Design Situations
Design for accidental actions Design for enhanced robustness (EN 1990)
(EN 1991)
Explicit design of the structure (e.g. Strategies based on limiting the extent of damage
against explosion, impact)
Design structure Prevent or reduce Alternative load Key elements i.e. Segmentation i.e.
to resist the the action e.g. paths either designing separation into
a
action protective providing selected members parts
measures, control adequate to resist notional
action(s)
of events deformation
capacity and
ductility or
applying
prescriptive
design rules
a
Structural design against identified accidental actions can incorporate specifically designed members, which
fall partially or fully, provided their failure does not lead to further structural collapse as agreed with the
authorities (for strategies and methods to limit the extent of damages, see E.3 and E.4 in EN 1990:2023)
(2) For some structures (e.g. construction works where there is no risk to human life, and where
economic, social or environmental consequences are negligible) subjected to accidental actions, the
complete collapse of the structure caused by an extreme event may be acceptable.
NOTE The decision criteria when such a collapse is acceptable can be given in the National Annex.
(3) Where appropriate, alternative load path design may be considered as an economic design method
for accidental actions.
NOTE The application of either a vertical load on more than one column or a horizontal load on more than one
beam allows for a redistribution of the action, if necessary. This can have also an effect on the load-bearing
resistances in the event of an impact or explosion.
4.2 Accidental design situations — strategies for identified accidental actions
(1) The accidental actions that should be taken into account depend upon:
— the measures taken for preventing or reducing the severity of an accidental action;
— the probability of occurrence of the identified accidental action;
— the consequences of failure due to the identified accidental action;
— public perception of the risk; and
— the level of acceptable risk.
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NOTE 1 In practice, the occurrence and consequences of accidental actions can be associated with a certain risk
level. If this level cannot be accepted, additional measures are necessary. A zero-risk level, however, is impracticable
and, in most cases, it is necessary to accept a certain level of risk. Such a risk level can be determined by various
factors, such as the potential number of casualties, the economic consequences and the cost of safety measures.
NOTE 2 Levels of acceptable risks can be given in the National Annex.
(2) A localized failure due to accidental actions may be acceptable, provided it will not endanger the
stability of the whole structure, and that the overall load-bearing capacity of the structure is maintained
and allows necessary emergency measures to be taken.
NOTE 1 For building structures, such emergency measures can involve the safe evacuation of persons from the
premises and its surroundings.
NOTE 2 For bridge structures, such emergency measures can involve the closure of the road or rail service within
a specific limited period.
(3) Measures should be taken to mitigate the risk of accidental actions and these measures should include,
as appropriate, one or more of the following strategies:
a) preventing the action from occurring (e.g. in the case of bridges, by providing adequate clearances
between the trafficked lanes and the structure) or reducing the probability and/or magnitude of the
action to an acceptable level through the structural design process (e.g. in the case of buildings,
providing sacrificial venting components with a low mass and strength to reduce the effect of
explosions);
b) protecting the structure against the effects of an accidental action by reducing the effects of the action
on the structure (e.g. by protective bollards or safety barriers); and/or
c) ensuring that the structure has sufficient robustness by adopting the robustness rules in EN 1990.
NOTE Protecting the structure by reducing the effects of an accidental action or preventing an action from
occurring can be difficult. This is because an action is dependent upon factors which, over the design working life
of the structure, can be outside the design assumptions. Preventative measures can involve periodic inspection and
maintenance during the design working life of the structure.
(4) The safety of the structure immediately following the occurrence of the accidental action shall be
addressed within an accidental design situation, for example where the evacuation of people is needed
4.3 Accidental design situations — use of consequence classes
(1) The strategies for accidental design situations may be based on the following consequence classes as
set out in EN 1990.
— CC1 Low consequences of failure
— CC2 Medium consequences of failure
— CC3 High consequences of failure
NOTE 1 In some circumstances it can be appropriate to treat some parts of the structure as belonging to a
different consequence class, e.g. a structurally separate low-rise wing of a building that is serving a less critical
function than the main building.
NOTE 2 The National Annex can provide a categorization of structures according to the consequences classes in
4.3(1).
NOTE 3 Table 4.2 (NDP) gives the classification of consequences classes for internal explosions for different
building types and occupancies, unless the National Annex gives a different categorization.
oSIST prEN 1991-1-7:2023
prEN 1991-1-7:2023 (E)
Table 4.2 (NDP) — Categorization of consequence classes for internal explosions.
a
Consequence Description Example of categorization of building type and occupancy
class of
consequence
class
CC 3 High All buildings defined above as Class 2 Lower and Upper
Consequences Class that exceed the limits on area and number of
storeys
All buildings to which members of the public are admitted in
significant numbers
Stadia accommodating more than 5 000 spectators
Buildings containing hazardous substances and/or processes
CC 2b Medium high Hotels, flats, apartments and other residential buildings greater
than 4 storeys but not exceeding 15 storeys
Upper Risk
Group Educational buildings greater than single storey but not exceeding
15 storeys
Retailing premises greater than 3 storeys but not exceeding 15
storeys
Hospitals not exceeding 3 storeys
Offices greater than 4 storeys but not exceeding 15 storeys
All buildings to which the public are admitted and which contain
2 2
floor areas exceeding 2 000 m but not exceeding 5 000 m at each
storey
Car parking not exceeding 6 storeys
CC 2a Medium low 5 storey single occupancy houses
Lower Risk Hotels not exceeding 4 storeys
Group
Flats, apartments and other residential buildings not exceeding 4
storeys
Offices not exceeding 4 storeys.
Industrial buildings not exceeding 3 storeys
Retailing premises not exceeding 3 storeys of less than 1 000 m
floor area in each storey
Single storey educational buildings
All buildings not exceeding two storeys to which the public are
admitted and which contain floor areas not exceeding 2 000 m at
each storey
CC 1 Low Single occupancy houses not exceeding 4 storeys
Agricultural buildings
Buildings into which people rarely go, provided no part of the
building is closer to another building, or area where people do go,
than a distance of 1,5 times the building height
a
For buildings intended for more than one type of use, the “consequence class” should be that relating to the
most onerous type. In determining the number of storeys, basement storeys may be excluded, provided such
basement storeys fulfil the requirements of “Consequences Class 2b Upper Risk Group”.
oSIST prEN 1991-1-7:2023
prEN 1991-1-7:2023 (E)
(2) Accidental design situations for the different consequence classes given in 4.3(1) may be considered
in the following manner:
— CC1: no specific consideration is necessary for accidental actions except to ensure that the robustness
and stability rules given in EN 1990 to EN 1999, as applicable, are met;
— CC2: depending upon the specific circumstances of the structure, a simplified analysis by equivalent
static action models may be adopted or prescriptive design/detailing rules may be applied;
— CC3: an examination of the specific case should be carried out to determine the level of reliability and
the depth of structural analyses required. This may require a risk analysis to be carried out and the
use of methods such as dynamic analyses, non-linear structural modelling and interaction between
the load and the structure.
NOTE The National Annex can give reference to appropriate design approaches for higher and lower
consequences classes.
(3) Preventative and/or protective measures are intended to remove or to reduce the probability of
damage to the structure. Their effect can be reflected in the design by, for example, assigning the structure
to a lower consequence class or using lower design forces.
5 Impact
5.1 Field of application
(1) This section defines accidental actions due to the following events:
— impact from road vehicles (excluding collisions on lightweight structures) (see 5.4);
— impact from forklift trucks (see 5.5);
— impact from trains (excluding collisions on lightweight structures) (see 5.6); and
— impact from ships (see 5.7);
— the hard landing of helicopters on roofs (see 5.8).
NOTE 1 Accidental actions on lightweight structures which are excluded from the field of application above (e.g.
gantries, lighting columns, footbridges) can be provided in the National Annex.
NOTE 2 For impact loads on kerbs and parapets and on bridge decks due to derailment, see prEN 1991-2.
NOTE 3 The National Annex can give guidance on issues concerning the transmission of impact forces to the
foundations.
(2) For buildings, actions due to impact shall be taken into account for:
— buildings used for car parking;
— buildings in which vehicles or forklift trucks are permitted; and
— buildings that are located adjacent to road or railway or waterway traffic.
(3) Actions due to impact from helicopters shall be taken into account for buildings where the roof
contains a designated landing pad.
oSIST prEN 1991-1-7:2023
prEN 1991-1-7:2023 (E)
5.2 Classification of actions
(1) Actions within the scope of this document shall be classified as accidental actions in accordance with
EN 1990:2023, 8.3.3.4.
(2) Accidental actions due to impact should be considered as free actions unless otherwise specified.
NOTE The National Annex can specify the treatment of accidental actions which are not classified as free
actions.
5.3 Representation of actions
(1) Actions due to impact should be determined by a dynamic analysis or represented by an equivalent
static force.
NOTE 1 The forces at the interface of the impacting object and the structure depend on their interaction.
NOTE 2 The basic variables for impact analysis are the impact velocity of the impacting object and the mass
distribution, deformation behaviour and damping characteristics of both the impacting object and the structure.
Other factors such as the angle of impact, the construction of the impacting object and movement of the impacting
object after collision can also be relevant.
NOTE 3 Guidance on dynamic design for impact is given in Annex C.
(2) For structural design the actions due to impact may be represented by an equivalent static force giving
the equivalent action effects in the structure. This simplified model may be used for the verification of
static equilibrium, for strength verifications and for the determination of deformations of the impacted
structure.
(3) The application of the dynamic or equivalent static horizontal design forces F and F should be
dx dy
defined.
NOTE Fdx does not act simultaneously with Fdy, unless the National Annex defines different rules for the
application of Fdx and Fdy.
(4) For structures which are designed to absorb impact energy by elastic-plastic deformations of
members (i.e. soft impact), the equivalent static loads may be determined by taking into account both
plastic strength and the deformation capacity of such members.
NOTE For further information, see Annex C.
(5) For structures for which the energy is mainly dissipated by the impacting body (i.e. hard impact), the
dynamic or equivalent static forces may be determined from subclauses 5.4 to 5.8.
NOTE Some information on parameters for masses and velocities of impacting objects as a basis for a dynamic
analysis can be found in Annex C.
5.4 Accidental actions caused by road vehicles
5.4.1 Impact on supporting substructures
(1) Design values for actions due to impact on the supporting structures (e.g. columns and walls of bridges
or buildings) adjacent to various types of roads should be defined.
NOTE 1 Equivalent static design forces for hard impact can be taken from Table 5.1 (NDP), unless the National
Annex gives different values.
oSIST prEN 1991-1-7:2023
prEN 1991-1-7:2023 (E)
Table 5.1 (NDP) — Equivalent static design forces due to vehicular impact on members
supporting structures over or adjacent to roadways
a b
Category of traffic Force F Force F
dx dy
[kN] [kN]
Motorways and country national and main roads 1 000 500
Country roads in rural area 750 375
Roads in urban area 500 250
Courtyards and parking garages with access to: 50 25
— Cars 150 75
c
— Lorries
a
x = direction of normal travel.
b
y = perpendicular to the direction of normal travel.
c
The term “lorry” refers to vehicles with maximum gross weight greater than 3,5 kN.
NOTE 2 The National Annex can prescribe the force as a function of distance s from the structural member to the
point where the vehicle leaves the trafficked lane and d the distance from the structural member to the centre-line
of the road or track. Information on the
...
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