ISO 22111:2007

INTERNATIONAL ISO
STANDARD 22111
First edition
2007-11-15


Bases for design of structures — General
requirements
Bases du calcul des constructions — Exigences générales




Reference number
ISO 22111:2007(E)
©
ISO 2007

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ISO 22111:2007(E)
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ISO 22111:2007(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Symbols . 5
5 Application . 7
6 Basic requirements for structural performance . 7
7 Classification of structures and elements of structures . 7
8 Actions. 8
8.1 General. 8
8.2 Evaluation of values of actions . 8
8.3 Permanent actions. 8
8.4 Variable actions . 8
8.5 Accidental actions . 9
9 Combinations of actions. 9
9.1 General. 9
9.2 Ultimate limit states. 9
9.2.1 Strength . 9
9.2.2 Static equilibrium. 10
9.3 Serviceability limit states. 10
9.4 Formats for presentation of design values for leading and accompanying actions. 10
10 Analysis and testing. 11
10.1 Analysis . 11
10.2 Testing . 11
11 Demonstrating compliance with requirements . 11
11.1 General. 11
11.2 Ultimate limit state. 12
11.2.1 Strength . 12
11.2.2 Static equilibrium. 12
11.3 Robustness . 12
11.4 Serviceability. 13
11.5 Durability . 13
Annex A (informative) Guidance for adopting groups . 14
Annex B (informative) Formats for presentation of design values for use in combinations of
actions . 17
Annex C (informative) Calibration of design values . 21
Annex D (informative) Design procedure. 22
Bibliography . 23

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ISO 22111:2007(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 22111 was prepared by Technical Committee ISO/TC 98, Bases for design of structures, Subcommittee
SC 2, Reliability of structures.
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ISO 22111:2007(E)
Introduction
This International Standard incorporates the general principles of structural design set out in ISO 2394. It
covers the partial factors method, and ISO 2394 should be consulted for other methods.
This International Standard is relevant to the design of any structure, and as with all standards, a degree of
judgement should be used in the normal course of engineering.
It has been drafted with wording and format suitable for direct use by practising engineers when the
appropriate levels of safety have been chosen, and the relevant national loading and materials standards
referenced by National Authorities. It is a template intended to facilitate the widespread use of International
Standards.
The annexes give guidance on adoption of this International Standard but need not be included in the National
Standard.
This International Standard has the following aims.
a) To facilitate international practice in structural design.
b) To obtain international standardization of the process for setting up rules for structural design, while
allowing each economy to specify its own levels of structural performance, in accordance with its own
needs.
c) To provide a means of promoting commonality, interchangeability, consistency and comparability of
structural standards developed by different economies. Regulators, standards writers, designers and
academics could then adopt such standards with confidence in their international acceptance.
d) To encourage regulatory authorities in each country to describe their mandatory requirements in an
internationally agreed format.
e) To facilitate future coordination between the various specialist subcommittees and working groups for ISO
structural Standards.
f) To create transparency in the process of comparison of National Standards.

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INTERNATIONAL STANDARD ISO 22111:2007(E)

Bases for design of structures — General requirements
1 Scope
This International Standard specifies the general requirements for the structural design of buildings and
industrial and civil engineering structures using reliability-based concepts.
This International Standard is applicable to the design of complete structures, the structural elements making
up the structure and the foundation. Information on the assessment of existing structures is given in
ISO 13822.
To allow for the differences in design practice between different countries, certain parameters are left to be
quantified by national building codes or standards.
2 Normative references
The following referenced documents are indispensable for the application 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.
ISO 2394:1998, General principles on reliability for structures
ISO 3898:1997, Bases for design of structures — Notations — General symbols
ISO 8930:1987, General principles on reliability for structures — List of equivalent terms
ISO 13822:2001, Bases for design of structures — Assessment of existing structures
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8930 and the following apply.
3.1
accidental action
action that is unlikely to occur with a significant value on a given structure over a given reference period
NOTE Adapted from ISO 8930:1987.
3.2
accompanying action
for a particular combination of actions, an action taken as being at a reduced value with respect to its
maximum extreme design value
3.3
characteristic value of an action
principal representative value of an action
NOTE 1 Adapted from ISO 8930:1987.
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ISO 22111:2007(E)
NOTE 2 It is chosen
a) either, when a statistical basis is available, so that it can be considered to have a prescribed probability of not being
exceeded (towards unfavourable values) during a reference period, or
b) on acquired experience, or
c) on physical constraints.
3.4
combination value of a variable action
value chosen, insofar as it can be determined on a statistical basis, so that the probability that the effects
caused by the combination will be exceeded is approximately the same as by the characteristic value of an
individual action
NOTE 1 It may be expressed as a certain part of the characteristic value by using a factor ψ u 1,0.
0
NOTE 2 Adapted from ISO 8930:1987.
3.5
deformability
deformability is the capacity to resist displacement-based actions
NOTE Examples of displacement-based actions are indirect actions such as seismic ground motions, differential
settlement and volume changes in structural materials.
3.6
design situation
set of conditions under which the design is required to demonstrate that relevant limit states are not exceeded
during a specific time interval
NOTE Adapted from ISO 2394:1998.
3.7
design working life
duration of the period during which a structure or a structural element, when designed, is assumed to perform
for its intended purpose with expected maintenance but without major repair being necessary
NOTE Adapted from ISO 2394:1998.
3.8
direct action
set of concentrated or distributed forces acting on the structure
[ISO 8930:1987]
3.9
durability
ability of a structure or a structural element to maintain adequate performance for a given time under expected
actions and environmental influences
3.10
dynamic action
action which causes significant accelerations of the structure or structural members
[ISO 8930:1987]
3.11
fixed action
action which has a fixed distribution on a structure, such as its magnitude and direction, determined
unambiguously for the whole structure when determined at one point on the structure
NOTE Adapted from ISO 8930:1987.
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ISO 22111:2007(E)
3.12
free action
action which may have any distribution in space over the structure, within certain limits
[ISO 8930:1987]
3.13
frequent value of a variable action
value determined, insofar as it can be determined on a statistical basis, so that either the total time, within the
reference period, during which it is exceeded is only a small part of the reference period, or the frequency of it
being exceeded is limited to a given value
NOTE 1 It may be expressed as a determined part of the characteristic value by using a factor ψ u 1,0.
1
NOTE 2 Adapted from ISO 8930:1987.
3.14
indirect action
set of deformations or accelerations imposed on a structure or constrained within it
NOTE Adapted from ISO 8930:1987.
3.15
leading action
for a particular combination of actions, the action that is taken to be at its maximum extreme design value
3.16
limit states
states beyond which a structure no longer satisfies the design requirements
[ISO 8930:1987]
NOTE These boundaries between desired and undesired performance of the structure are often represented
mathematically by “limit-state functions”.
3.17
maintenance
total set of activities performed during the design working life of a structure to enable it to fulfil the
requirements for reliability
[ISO 2394:1998]
3.18
occupancy action
variable action imposed on the structure due to the intended use or occupancy of the structure
3.19
partial factors format
calculation format in which allowance is made for the uncertainties and variabilities assigned to the basic
variables by means of representative values, partial factors and, if relevant, additive quantities
[ISO 2394:1998]
NOTE The load and resistance factor format is a version of the partial factor format.
3.20
permanent action
action which is likely to act throughout a given reference period of time, and for which the variation in
magnitude with time around its mean value is negligible, or for which the variation is monotonic (i.e. always in
the same direction) until the action attains a certain limiting value
NOTE Adapted from ISO 8930:1987.
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ISO 22111:2007(E)
3.21
quasi-permanent value of a variable action
value determined so that the total period of time for which it is exceeded is a large fraction of the reference
period
NOTE 1 It may be expressed as a determined part of the characteristic value by using a factor ψ u 1,0.
2
NOTE 2 Adapted from ISO 8930:1987.
3.22
reference period
chosen period of time that is used as a basis for assessing the design value of variable or accidental actions
or both
NOTE Adapted from ISO 8930:1987.
3.23
reliability
ability of a structure or structural element to fulfil the specified requirements, including the design working life,
for which it has been designed
[ISO 2394:1998]
3.24
representative value of an action
value assigned to the action for a specific purpose
NOTE 1 Adapted from ISO 8930:1987.
NOTE 2 It can be used, for instance, for the verification of a limit state.
3.25
robustness
ability of a structure (or part of it) to withstand events (like fire, explosion, impact) or consequences of human
errors, without being damaged to an extent disproportionate to the original cause
NOTE 1 Adapted from ISO 2394:1998.
NOTE 2 Robustness is sometimes referred to as structural integrity.
3.26
strength
ability of a cross-section or an element of a structure to withstand actions without mechanical failure
EXAMPLES Bending strength, buckling strength, tension strength.
3.27
serviceability limit states
states corresponding to conditions beyond which specified serviceability requirements for a structure or
structural element are no longer met
NOTE 1 Adapted from ISO 2394:1998.
NOTE 2 They are related to the user’s comfort, function of the structure or element, risk of deterioration, or intended
maintenance.
3.28
static action
action that does not cause significant acceleration of a structure or a structural element
NOTE Adapted from ISO 8930:1987.
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ISO 22111:2007(E)
3.29
structural model
idealization of the structural system used for the purposes of analysis, design and verification
[EN 1990:2002]
3.30
ultimate limit states
states associated with collapse, or with other similar forms of structural failure
NOTE They generally correspond to the maximum load-carrying resistance of a structure or structural element but in
some cases to the maximum applicable strain or deformation.
[ISO 2394:1998]
3.31
variable action
action for which the variation in magnitude with time is neither negligible in relation to the mean value nor
monotonic
NOTE Adapted from ISO 8930:1987.
4 Symbols
The symbols used in this International Standard follow the guidelines given in ISO 3898 and ISO 2394.
A: accidental action
A : design value of a leading accidental action (see Annex B)
d
C : serviceability limit; see Equation (5)
d
E: design-action effect
d
E : design effect of destabilising actions
d,destab
E : design effect of stabilising actions
d,stab
F: action in general
F , F: various actions
i j
G: permanent action
G : permanent action for a particular combination
i
G : the component of the permanent action that is relied upon to stabilise the structure (see 9.2.2)
ki,stab
G : characteristic value of permanent action (see Annex B)
k
G : characteristic permanent action for a particular combination (see 9.2.1)
k,i
G : lower characteristic value of permanent action (see Annex B)
kj,inf
G : higher characteristic value of permanent action (see Annex B)
kj,sup
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ISO 22111:2007(E)
Q: variable action
Q : characteristic value of a variable action in a combination
k
Q : characteristic value of a leading variable action (see 9.2.1)
k,1
Q : characteristic value of an accompanying variable action (see 9.2.1)
k,i
R: design resistance
d
R : design resistance of the restraining elements (if any)
s
β: reliability index (beta)
β , β , β , β : values of reliability index appropriate to various consequence levels
I II III IV
γ : partial factor (gamma)
γ : factor applied to the characteristic action to determine the accompanying action (see B.2)
a,i
γ : partial factor of the accompanying variable action
i
γ : partial factor for leading variable or accidental action
j
γ : partial material factor
m
γ : the load factor for the permanent action that is relied upon to stabilise the structure
Gi,stab
γ : factor for the lower combination value of a permanent action (see Annex B)
Gj,inf
γ : factor for the higher combination value of a permanent action (see Annex B)
Gj,sup
γ , γ : partial factors for various permanent actions
G Gi
γ : factor for combination value of an accompanying variable action (see Annex B)
Qi
γ : factor for combination value of a leading variable action (see Annex B)
Q,1
ψ : factor for combination value of a particular action (psi)
i
ψ : factor for combination of a variable action
0
ψ : factor for frequent value of a variable action (see Annex B)
1
ψ : factor for quasi-permanent value of a variable action (see Annex B)
2
ψ : factor for quasi-permanent value of a leading variable action (see Annex B)
2,1
ψ : factor for quasi-permanent value of an accompanying variable action (see Annex B)
2,i
φ: resistance factor
ξ : reduction factor for unfavourable permanent actions (see B.1)
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ISO 22111:2007(E)
5 Application
When this International Standard is used to develop a National Standard, appropriate values for those factors
not specified shall be determined in accordance with ISO 2394 using the appropriate International and
National Standards, which shall be mutually consistent.
NOTE Guidance on the application of this International Standard is given in Annexes A to D.
6 Basic requirements for structural performance
A design working life shall be selected for the structure. The structure shall be designed, constructed and
maintained in such a way that during construction and for its design working life it will, with appropriate
degrees of reliability, sustain all actions and influences likely to occur. It shall be designed with the following:
a) ultimate limit-state requirements: to withstand extreme or frequently repeated actions, or both, occurring
during its construction and anticipated use;
b) robustness requirements: so that it will not be damaged to an extent disproportionate to the original cause,
by events like fire, explosion or impact or as a consequence of human error;
c) serviceability requirements: to perform adequately under all expected actions;
d) durability requirements: to satisfy all of the above for its design working life, given appropriate
maintenance.
Compliance with these requirements shall be demonstrated by verifying that the structure and its elements
satisfy a specified set of limit-state conditions in accordance with the principles of Clause 11.
7 Classification of structures and elements of structures
Structures and elements of structures shall be classified according to Table 1.
For the purposes of demonstrating compliance under 11.2, structures shall be classified in terms of
consequences of failure in accordance with Table 1.
Table 1 — Classification of structures and elements of structures
Consequence Consequences of
Comments
a b
class failure
Low consequence for loss of human life, or small or moderate
I Low
economic, social or environmental consequences
Medium consequence for loss of human life, or considerable economic,
II Ordinary
social or environmental consequences
High consequence for loss of human life, or very great economic, social
III High
or environmental consequences
IV Exceptional Circumstances where reliability must be set on a case-by-case basis
a
Examples of structures that fit into these classes are to be given in the annex of the adopting group or stated elsewhere (see
Annex C).
b
To life or to society.
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ISO 22111:2007(E)
8 Actions
8.1 General
All physical conditions likely to affect the performance of the structure shall be considered.
8.2 Evaluation of values of actions
Actions shall be evaluated in accordance with the following:
a) the nature of the action (including whether fixed or free, static or dynamic and frequency of occurrence);
b) the consequence class;
c) the design working life of the structure.
8.3 Permanent actions
Permanent actions (G) include, but are not limited to, the following:
a) self-weight of the structure (except possibly certain parts during certain phases of construction);
b) weight of superstructures, including any permanent formwork or fixtures;
c) forces applied by static earth pressure, resulting from the mass of the soil;
d) deformations imposed by the construction sequence of the structure;
e) action resulting from shrinkage of concrete and from welding;
f) action due to fluids, where permanent;
g) action due to subsidence (support settlements and mining);
h) pre-stressing action.
NOTE Information on permanent actions is given in the relevant International Standards, e.g. ISO 9194.
8.4 Variable actions
Variable actions (Q) include, but are not limited to, the following:
a) action imposed due to use and occupancy action;
b) wind action;
c) snow action;
d) seismic action;
NOTE 1 Seismic action can be categorised as accidental action if so designated in the national building code or
standard.
e) action due to ponding of water;
f) action due to fluids, where variable;
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ISO 22111:2007(E)
g) action due to forces and effects arising from contraction or expansion resulting from temperature changes,
moisture changes, creep, and from movement due to differential settlement;
h) ice action;
i) action due to currents;
j) action due to waves;
k) action due to moving loads and their effects;
l) action applicable to a specific situation.
NOTE 2 Information on variable actions is given in the relevant International Standards, e.g. ISO 2103, ISO 2633,
ISO 3010, ISO 4354, ISO 4355, ISO 12494.
8.5 Accidental actions
Accidental actions (A) include, but are not limited to, the following:
a) action due to fire;
b) action due to explosion;
c) action due to collision;
d) seismic action;
NOTE 1 Seismic action can be categorised as variable action if so designated in the national building code or standard.
e) action due to vegetation;
f) action due to erosion;
g) action applicable to a specific accidental situation.
NOTE 2 Accidental actions are not normally assessed unless specifically applicable.
NOTE 3 For fire action, the structural performance is defined in terms of the structural resistance for a required period
of time, while the structure is under the effects of fire and other actions.
9 Combinations of actions
9.1 General
Actions shall be considered to act in the following combinations, whichever produces the most unfavourable
effect in the structure, foundation or structural element being considered. Effects of one or more variable
actions not acting shall be considered, if they produce more unfavourable effects.
9.2 Ultimate limit states
9.2.1 Strength
The design-action effects (E ), for examining strength (and deformation, where applicable) shall be
d
determined by combining the values of uncorrelated actions, both unfavourable and favourable, that are
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ISO 22111:2007(E)
considered to occur simultaneously. Sufficient combinations shall be made to evaluate all realistic limit-state
conditions. Each combination of actions shall include the following:
a) all permanent actions Σ (γ G );
Gi k,i
b) the design value of one leading variable or accidental action (γ Q );
k,1 k,1
c) the design combination values of accompanying variable actions Σ (γ ψ Q ).
i i k,i
E may be expressed as a combination as follows:
d
γγGQ;;γψQ (1)
()() ( )
{}∑∑Gi ki,,j k1 i i ki,
NOTE 1 For correlated acti
...