ISO/TR 12470:1998

Fire-resistance tests - Guidance on the application and extension of results

Essais de résistance au feu — Recommandations pour l'application et l'extrapolation des résultats

Preskusi požarne odpornosti – Navodila za širšo uporabo rezultatov

General Information

• Status: Withdrawn
• Publication Date: 15-Jul-1998
• Withdrawal Date: 15-Jul-1998
• ICS: 13.220.40 - Ignitability and burning behaviour of materials and products
• ICS: 13.220.50 - Fire-resistance of building materials and elements
• Technical Committee: ISO/TC 92/SC 2 - Fire containment
• Drafting Committee: ISO/TC 92/SC 2/WG 2 - Calculation methods
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 10-Dec-2013
• Completion Date: 13-Dec-2025
• Ref Project: SIST ISO/TR 12470:1999 - Fire-resistance tests -- Guidance on the application and extension of results

Relations

• Revised: ISO/TR 12470-1:2017 - Fire-resistance tests - Guidance on the application and extension of results from tests conducted on fire containment assemblies and products - Part 1: Loadbearing elements and vertical and horizontal separating elements
• Effective Date: 07-Dec-2013
• Revised: ISO/TR 12470-2:2017 - Fire-resistance tests - Guidance on the application and extension of results from tests conducted on fire containment assemblies and products - Part 2: Non-loadbearing elements
• Effective Date: 07-Dec-2013

Standards Content (Sample)

TECHNICAL ISO/TR
REPORT 12470
First edition
1998-07-15
Fire resistance tests — Guidance on the
application and extension of results
Essais de résistance au feu — Recommandations pour l’application et
l’extrapolation des résultats
A
Reference number
Contents Page
1  Scope . 1
2  Common factors . 2
2.1  Manufacture and materials . 2
2.2  Moisture content. 3
2.3  Increasing size. 4
3  Loadbearing elements. 4
3.1  Beams . 4
3.2  Columns . 6
3.3  Floors. 8
3.4  Walls . 10
4  Non-loadbearing elements. 13
4.1  Vertical partitions . 13
4.2  Ceiling membranes (Horizontal partitions). 15
4.3  Doors - Hinged and pivoted leaves. 16
4.4  Lift landing doors — Centre opening and two-speed lift
landing doors. 21
4.5  Rolling shutters . 24
4.6  Glazed elements . 27
5  Components contributing to the fire resistance of elements . 30
5.1  Suspended ceilings. 30
5.2  Insulating systems . 33
6  Service installations . 35
6.1  Ducts. 35
6.2  Dampers . 38
6.3  Penetration seals. 40
©  ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet [e-mail]
Printed in Switzerland
ii
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ISO ISO/TR 12470:1998(E)
7  Future evolution. 42
7.1  Improvement of testing methodologies . 42
7.2  Mathematical modelling of thermal
and mechanical response. 44
7.3  Expert system based upon the use of performance
coefficients. 46
Annex A: Summary of general practices in various countries
as far as interpolation and extrapolation are concerned. 49
Annex B: Current practices in various countries . 53
Annex C: Bibliography . 59
iii
©
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.
The main task of technical committees is to prepare International
Standards, but in exceptional circumstances a technical committee may
propose the publication of a Technical Report of one of the following types:
— type 1, when the required support cannot be obtained for the
publication of an International Standard, despite repeated efforts;
— type 2, when the subject is still under technical development or where
for any other reason there is the future but not immediate possibility of
an agreement on an International Standards;
— type 3, when a technical committee has collected data of a different
kind from that which is normally published as an International Standard
(“state of the art”, for example).
Technical Reports of types 1 and 2 are subjected to review within three
years of publication, to decide whether they can be transformed into
International Standards. Technical Reports of type 3 do not necessarily
have to be reviewed until the data they provide are considered to be no
longer valid or useful.
ISO/TR 12470, which is a Technical Report of type 2, was prepared by
Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 2, Fire
resistance.
The primary objective of this Technical Report is to produce a harmonized
approach to the extension of results obtained from fire resistance tests
performed according to the time-temperature curve as given in ISO 834-1.
Such an approach is usable by writers of fire testing standards to assist
with the preparation of harmonized “field of direct application” statements.
In addition it is of assistance to fire safety engineers/consultants who either
need to establish the extended field of application of a tested construction,
to establish whether a similar untested element would be expected to
satisfy the test criteria where the variations between the tested and
untested constructions are significant, or produce the rules governing the
application.
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ISO ISO/TR 12470:1998(E)
The guidance as to whether the application can be extended is given in
three forms. In the simplest form a rule may be used which may be based
upon sound scientific facts or even just custom and practice. For
quantifiable aspects it identifies where fire engineering calculations may be
used. Where judgement needs to be exercised, it identifies the factors that
need to be considered. The guidance given also allows a designer or the
enforcing authority to assess the fire resistance of an element when it is of
a size that cannot be tested due to the physical limitations of testing
furnaces. Whether this is a valid use of this guidance document will depend
upon the philosophy of a particular country's regulations and the way they
use fire resistance tests in their building codes. In a complex building
where the behaviour can only be established from first principles, a greater
understanding of the limitations applying to a test result is critical.
Structural elements such as beams, girders, columns and floors are
generally designed by using calculation methods applicable at room
temperature and each element is more or less different from one another.
These structural elements also need calculation methods that assess their
fire behaviour and it is important that these are correlated by tests.
Annex A forms an integral part of this Technical Report. Annexes B and C
are for information only.
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Introduction
Fire resistance tests on building components are necessary to establish
their behaviour against pre-determined criteria when exposed to a
representative fully developed fire and to provide information that may be
used in determining the fire safety level of buildings. For several decades
people have accepted by means of test results only, the possibility of
grading the components. Now, due to the improvement of knowledge and
the sophistication of buildings, it is necessary to be able to give a more
accurate assessment of the components used in buildings.
Because of the cost of the tests and the size limitations of the testing
furnaces, it is not possible for any given building element to be tested at all
of its various sizes or designs. As a consequence we need rules or even
better mathematical models for predicting, from test results, the behaviour
of elements which are changed in size, design and/or application. The
performance of these elements is adjudged as a separate consideration
and only against standard heating conditions as defined in ISO 834-1.
Even with the knowledge available to assess the behaviour of a given
constructional element, whatever its design or its size, we will still be a long
way from establishing the real behaviour of a building in a real fire.
The philosophy of only grading elements into different fire resistance
categories may not give any indication about how the element behaves
when heated. By studying and assessing the data from fire resistance
tests, it will be possible, using the guidance within this Technical Report, to
obtain a basic understanding of the influence of the main parameters on
the element performance during a fire resistance test.
In practice, tests can give much useful information which can be used for
interpolation and extrapolation of the results.
In the following, all of these assessments will be based on the one hand on
the standard time/temperature conditions and, on the other hand, on
isolated elements with no interaction with the adjacent elements.
Also ageing and weathering are not covered here.
This Technical Report is divided in two parts:
— guidance on direct use and extended application of test results for
various elements used in buildings; the parameters which would be
assessed by rules, calculation or only expert judgements are dis-
cussed.
— future evolution:
• improvement of testing methodologies to give a better prediction
of the performance of various sizes and designs of a given
element,
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ISO ISO/TR 12470:1998(E)
• mathematical modelling which can be used by experts to give
their judgement,
• expert systems which could take into account the interaction of
various factors in an assessment.
In addition annexes A and B give an overview of current practices in
various countries as far as application and extension of fire resistance test
results are concerned. It is mentioned where agreement could be found
and where more efforts have to be made for harmonization.
Annex C gives additional reading.
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TECHNICAL REPORT  ISO ISO/TR 12470:1998(E)
Fire resistance tests — Guidance on the application and
extension of results
1  Scope
Direct and extended applications of test results are the two possible ways to ensure that a modified element will
have a good possibility of obtaining the same fire rating as that of the original tested specimen. In both cases these
applications refer only to the fire rating that the building element can expect to reach if it were to be tested in a
furnace according to the standard fire used for the reference test.
For each type of element of construction, the application of test results will be considered under two sub-headings.
a) Direct application: this section identifies the modifications that can be made to the design of the tested element
without reducing its fire rating. These possible modifications are based on obvious knowledge and do not need
further evaluation. In every case it is, at least, assumed that the basic materials used for the tested sample will
not be changed. The results obtained from tests performed using standard configurations are valid for the field
of application derived from that configuration, regardless of any specific advice given in the following chapters.
b) Extended application: this will require in every case an assessment by a fire expert either in developing rules of
application or evaluating the results of fire engineering calculations or making a judgement. In every case it will
be taken into consideration that extended application may take into account the difference between the result of
the original test and the fire resistance required for the untested element.
A judgement is the result of a qualitative process, normally carried out by experts. Judgements are used to
justify a change of design or method of construction which may use, for example, empirical data derived from
tests, established physical properties, hot and cold state calculations, a knowledge of fire exposure, fire
behaviour and response of the construction, either in isolation or in combination.
1) Rules of application: these would be applied universally even by persons without expertise in fire as part of
the "field of application" of the test result for a given family of products. These rules may require cold state
calculation. The quantification of these rules would be agreed universally based upon validated experience
related to generic constructions or components. This could cover size changes, number of joints, size of
glazing etc.
Throughout this Technical Report the clauses covering rules frequently express the acceptable change in
terms of un-quantified percentages indicated by the letter "X" and an appropriate suffix.
This allows national code authorities to insert their own acceptable limits which will relate to their
established fire safety philosophy.
Authorities are encouraged to support the necessary research towards internationally harmonized
validated value.
2) Fire engineering calculations: these would be used by an expert in giving advice but will mainly be
restricted to the properties indicated below:
©
ISO
• non-loaded elements: this would be restricted to the calculation of temperature rise and deflection of
"simple" components and elements;
• loaded element: in addition to the properties permitted for non-loaded elements, calculation at
elevated temperature could be permitted for the load-bearing capacity for well-documented materials
(steel, concrete, etc.) and for statically determined elements.
In every case the calculation models used by the experts, whatever their source (purchased from software
manufacturers or developed in the institution) have to be fully validated by comparison with existing test
results and by sensitivity analysis of the various parameters.
3) judgements: for a test result to be extrapolated to cover changes outside those for which calculations or
written rules are applicable, the result may still apply subject to some expert judgement being made. The
section on judgements highlights the matters that need to be considered and to be explained by the body
or person responsible for making such judgements. Generally, components of a construction element
could be changed, provided it can be shown that this does not reduce the fire resistance. It must be
demonstrated that the interaction of a new component with other components will not affect adversely the
performance of the tested construction. When resistance time is higher than required time, it will generally
be possible to have a greater change than with only the necessary safety level.
Changes in materials and methods of construction can have significant influences on the fire resistance. Because
the advice and recommendations are common to all elements, those aspects are dealt with separately under 2.1.1
"manufacture and materials" to avoid repetition. The user of this Technical Report should consider these aspects in
all applications of results whether direct or extended.
2  Common factors
The advice in this clause applies to all subsequent groups of elements.
2.1  Manufacture and materials
2.1.1 General
For certain applications, even small changes in either the materials or the methods of manufacturing may result in
large changes in fire resistance (for example glazing, intumescent coatings, primers). The results from a fire
resistance test may be used to support an evaluation of the performance of a similar untested element or they may
be used to justify an element in use without any further calculations, or the application of rules, if the manufacture of
the element complies with the guidance given in 2.1.2. Where the construction is not covered by the direct
application then the calculations or application rules need to be applied as indicated.
Additionally there are quality control and certification schemes in some countries. Control procedures ensure that
the untested construction is equivalent to the tested construction. Any relaxation of these procedures may only be
undertaken if it can be established that they only influence non-critical aspects of the construction (e.g. colour,
texture, etc.) Evidence of the effect must be available if the control of the 'critical' processes or materials is involved.
Reduced scale fire resistance tests may be used for this purpose subject to the changes not affecting distortion.
The information given for direct and extended applications has to be used for every construction element.
2.1.2 Direct application
a) The quality control procedures are not reduced.
b) The manufacturing/construction procedures remain unchanged.
c) Constituent materials, admixtures, preservatives, flame retardants, adhesives, etc. remain unchanged.
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ISO
2.1.3 Extended application
2.1.3.1 Rules
As a general rule the quantity of any constituent material may be varied by up to a certain percentage (to be defined
for each family of material) from that used in the original specification that was tested without the need for further
consideration.
2.1.3.2 Fire engineering calculations
Where, for certain materials, calculation methods have evolved and been documented it may be possible to
calculate the influence that changes in material and manufacturing may have on the fire resistance.
2.1.3.3 Judgements
a) Materials
It may be possible to change constituent materials, or add constituents such as preservatives or flame retardants
without significantly affecting the fire resistance. Evidence of the effect that this may have should be available or its
effect should be able to be calculated to demonstrate that these changes will not reduce the fire resistance.
Reduced scale fire resistance tests may be suitable for this purpose. If the additional constituents may be expected
to influence distortion patterns, then a full scale test may be required.
b) Manufacturing procedures
The effect of any change in the manufacturing procedure shall be established to show that it does not reduce the
fire resistance of the element before such changes are accepted.
2.2  Moisture content
Since it is difficult to measure the moisture content of many elements prior to the test, it is better to try to reach an
equilibrium before testing. However when for various reasons this is not possible and if information is available on
the assumed moisture content, the following correction can be used.
If the fire resistance with respect to insulation criterion of a specimen is known at one moisture content, then the
1)
insulation rating at some other moisture content can be corrected according to the following equation :
TT++()4 bf-T-40T=
dd ff
where
f is the volumetric moisture content,
T is the fire resistance, in minutes, of the element at a moisture content of f,
f
T is the fire resistance, in minutes, of the element in oven-dry condition,
d
b is a factor, in minutes, which varies with the permeability.
This formula can be used for correcting the insulation criteria relating to a homogeneous structural element such as
concrete slabs, brick walls, with some limits of application. It is not applicable to timber and gypsum products.

1)  T.Z. HARMATHY, "Fire Safety Design and Concrete". Longman Scientific & Technical, 1993.
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ISO
2.3  Increasing size
A non-loadbearing separating element having obtained a given fire rating could be used for a lower fire rating
application at a bigger size than that allowed in an application requiring the obtained fire rating. The reason for this
is that to achieve a better performance than that required it is necessary to produce a more stable element to
ensure reduced distortion and/or deformation and hence less erosion of any constitutive materials.
3  Loadbearing elements
In practice few structural elements are covered by direct application because there is always a difference in size or
strength of material used.
For protected load bearing elements, please refer also to 5.2.
For simple elements, it is normal to use design codes which take fire into account.
3.1  Beams
3.1.1 General
The results from a fire resistance test may be used to support an evaluation of the performance of another beam
without any further calculations or the application of rules or judgements if the construction complies with the
guidance given in 3.1.2. Where the construction does not comply with the direct application, then the calculations or
application rules or judgements need to be applied as indicated.
The relevant performance criterion is the loadbearing resistance (loadbearing capacity: determined by maximum
deflection and maximum rate of deflection).
3.1.2 Direct application
The results of a fire resistance test are deemed to be applicable to a similar untested beam provided that all the
following are true.
a) The span is not increased.
b) The load is not increased and the location and distribution of the load are unchanged.
c) The rotational and longitudinal restraint are unchanged.
d) The dimensions of the cross-section are not reduced.
e) Characteristic strength and density of any basic materials are unchanged.
f) The number of heated surfaces is unchanged.
g) The length of the unheated part of the construction is not reduced.
h) There is no change in the design of the cross-section (e. g. reinforcing bars within the cross-section).
i) Lining or decorative materials not influencing the fire resistance may be changed or added.
3.1.3 Extended application
3.1.3.1 Rules
Rules can be given for the following.
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ISO
a) Dimensions and loading (length of span, level and type of load)
The length and load (level and distribution) may be changed as long as it can be calculated that the stresses
(bending and shearing) within the section are not increased, and providing that failure mode at room
temperature does not change (the span could be increased if the load is reduced and vice versa).
b) Reinforcement for reinforced concrete beams (not relevant for prestressed concrete beams)
A change in the location of reinforcement is possible as long as its temperature is not increased, the total cross-
section is not reduced, and the distance between the reinforcement and the centroid of the compressive zone is
not reduced.
c) Number of heated surfaces
The number of heated surfaces may be reduced for beams made of materials where this is not detrimental to
the performance.
d) Services
Holes for services may be incorporated if they are perpendicular to the span and in the zone of the neutral axis,
provided that they are protected at their borders in the same way as the beam itself.
e) Lining materials
Lining or decorative materials not influencing the fire resistance may be changed or added.
3.1.3.2 Fire engineering calculations
Calculations may be used for the following.
a) Temperature profile
Heat transfer through beams may be calculated by using an accepted temperature analysis model. Input data
must be based on values for specific heat capacity and thermal conductivity as a function of temperature for all
materials included in the element. For composite elements it is necessary to estimate, using relevant test
results, the time of exposure at which destruction or detachment of parts of the element (i.e. boards, insulation
etc.) will occur.
b) Load bearing resistance (load bearing capacity)
The load bearing resistance may be calculated for beams where the physical properties are known as a
function of temperature and where the temperature profile over the cross-section of the beam is known. For
timber the charring rate and hence the reduction in cross-section also need to be known.
c) Deflection
The deflection may be calculated for beams where the relationships between stress and strain (including, if
necessary, creep effect) as a function of temperature are known, in addition to the above properties. It should
be noted that the calculated deflections need to take into account deflections due to both the thermal and load
induced strains.
3.1.3.3 Judgements
Changes may be made to the following aspects of the beams provided that expert judgement is based on the
appropriate considerations mentioned below.
a) Supporting conditions
The supporting conditions may be changed, provided that this will not increase the load effect, reduce the
rotational restraint, or increase the longitudinal restraint or the thermal conditions.
©
ISO
b) Protecting materials
When fire protection materials are changed or increased in order to compensate for changes in the load case
or cross-sectional area, it must be demonstrated (justified) that the connection between the protective material
and the beam will remain effective for a duration sufficient to achieve the fire resistance period.
c) Heated surfaces
The number and area of heated surfaces can be increased, if it can be demonstrated that in increasing the
height of the cross-section or decreasing the perimeter/area ratio (for instance) the load bearing resistance is at
least the same as the resistance of the tested beam.
d) Components
Components of the beam construction (additional support for floors or the other beams) can be added, provided
that it can be shown that this does not reduce the fire resistance.
e) Services
Holes in beams perpendicular to their span may be allowed provided the stresses (bending and shear) at the
location of the holes do not exceed the corresponding maximum stresses in the tested beam and the holes are
protected at their edges in order to avoid excessive increase of temperature.
f) Protecting holes
Where holes are made in a beam which is protected, it is necessary for the boundary of the hole to be provided
with an equivalent level of protection.
3.2  Columns
3.2.1 General
The results from a fire resistance test may be used to support an evaluation of the performance of another column
without any further calculations or the application of rules or judgements if the construction complies with the
guidance given in 3.2.2. Where the construction does not comply with the direct application then the calculations or
application rules or judgements need to be applied as indicated.
The relevant performance criterion is the loadbearing resistance (loadbearing capacity: determined by maximum
axial contraction and maximum rate of axial contraction).
3.2.2 Direct application
The results of a fire resistance test are deemed to be applicable to a similar untested column provided that all the
following are true.
a) The length is not increased.
b) The load is not increased and its eccentricity is not increased.
c) The end conditions are unchanged.
d) The dimensions of the cross-section are not reduced.
e) Characteristic strength and density of any basic materials are unchanged.
f) The number of heated surfaces is unchanged.
g) There is no change in the design of the cross-section (e. g. reinforcing bars within the cross-section).
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ISO
3.2.3 Extended application
3.2.3.1 Rules
Rules can be given for the following.
a) Dimensions (including length), loading and end conditions
The length, slenderness and load may be changed as long as it can be calculated that the load level is not
increased, e.g. the length can be increased if the load is reduced or the end conditions result in a lower
slenderness ratio and vice versa.
b) Reinforcement for reinforced concrete columns (not applicable to prestressed concrete)
A change in the location of reinforcement is possible as long as its temperature is not increased, there is no
bending moment and the total cross-section is not reduced.
c) Services
Holes with a diameter less than or equal to X for services in concrete columns are allowed where the
thickness of the material on both sides of the hole has a minimum of X . The hole shall not remove any
reinforcement.
d) Lining materials
Lining or decorative materials not influencing the fire resistance may be changed or added.
3.2.3.2 Fire engineering calculations
Calculations may be used for the following.
a) Temperature profile
Heat transfer through columns may be calculated by using an accepted temperature analysis model. Input data
must be based on values for specific heat capacity and thermal conductivity as a function of temperature for all
materials included in the element. For composite elements it is necessary to estimate, using relevant test
results, the time of exposure at which destruction or detachment of parts of the element (i.e. boards, insulation
etc.) will occur.
b) Load bearing resistance
The load bearing resistance may be calculated for columns where the physical properties are known as a
function of temperature and where the temperature profile over the cross-section of the column is known. For
timber the charring rate and hence the reduction in cross-section also need to be known.
c) Deformation
The deformation (axial and lateral) may be calculated for columns where the relationships between stress and
strain (including, if necessary, creep effect) as a function of temperature are known, in addition to the above
properties. It should be noted that the calculated deformation needs to take into account deformations due to
both thermal and load induced strains.
d) Services
Holes for services in concrete columns or holes in columns of material other than concrete, perpendicular to the
length, are allowed if it can be calculated that they do not reduce the load bearing resistance at elevated
temperature.
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ISO
3.2.3.3 Judgements
Changes may be made to the following aspects of the columns provided the expert judgement is based on the
appropriate considerations mentioned below.
a) Supporting conditions
The supporting conditions may be changed, provided that this will not increase the load effect or reduce the
rotational or the thermal conditions.
b) Protecting materials
When fire protection materials are changed or increased in order to compensate for changes in the load case
or cross-sectional area, it must be demonstrated (justified) that the connection between the protective material
and the column shall remain effective for a duration sufficient to achieve the fire resistance period.
c) Components
Components of the column (brackets etc.) can be added, provided that it can be shown that this does not
reduce the fire resistance.
d) Protecting holes
Where holes are made in a column which is protected, it is necessary for the boundary of the hole to be
provided with an equivalent level of protection.
3.3  Floors
3.3.1 General
The results from a fire resistance test may be used to support an evaluation of the performance of another floor
without any further calculations or the application of rules or judgements if the construction complies with the
guidance given in 3.3.2. Where the construction does not comply with the direct application then the calculations or
application rules or judgements need to be applied as indicated.
The relevant performance criteria are integrity (measured by gap gauge, ignition of cotton pad, or sustained
flaming), insulation (increase of average or maximum temperature) and loadbearing resistance (loadbearing
capacity: determined by maximum deflection and maximum rate of deflection).
3.3.2 Direct application
The results of a fire resistance test are deemed to be applicable to a similar untested floor, provided that all the
following are true.
a) The span is not increased and, in the case of a two-way spanning floor, the span ratio is unchanged.
b) The load is not increased and the location and distribution of the load are unchanged.
c) The rotational and longitudinal restraint are unchanged.
d) The thickness is not reduced.
e) Characteristic strength and density of any basic materials are unchanged.
f) Thermal insulation is not reduced at any point over the whole area.
g) The length of unheated parts of the construction is not reduced.
h) There is no change in the design of the cross section (e. g. the location of reinforcing bars).
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ISO
3.3.3 Extended application
3.3.3.1 Rules
Rules can be given for the following.
a) Dimensions
The width of the floor can be increased provided sufficient space is allowed at the edges to permit the
increased thermal expansion without leading to system failure.
b) Dimensions and loading
The span can be increased provided the load is reduced or the load can be increased provided the span is
reduced. The changes to the loading or the span must not increase stress levels within the section in excess of
the design stresses associated with the fire design load case.
Any changes to the loading or the span must not change the mode of failure.
If the thickness of the floor is reduced corresponding to a reduction in the load in order to maintain the same
stress levels, the thickness may not be reduced to such an extent that the floor will not provide adequate
insulation.
c) Change in density
Where light weight concrete is substituted for normal weight concrete, the thickness of the slab may be reduced
by X % in respect of the insulation criterion as long as the loadbearing capacity is satisfactory. The temperature
of steel beams and the temperature of steel floors in contact with the concrete will increase when light weight
concrete replaces normal weight concrete.
d) Lining materials
Lining or decorative materials not influencing the fire resistance may be changed or added.
3.3.3.2 Fire engineering calculations
Calculations may be used for the following.
a) Temperature profile
Heat transfer through floors may be calculated by using an accepted temperature analysis model. Input data
must be based on values for specific heat capacity and thermal conductivity as a function of temperature for all
materials included in the element. For composite elements it is necessary to estimate, using relevant test
results, the time of exposure at which destruction or detachment of parts of the element (i.e. boards, insulation
etc.) will occur.
b) Insulation performance
Compliance with the insulation criterion may be calculated using appropriate temperature profiles.
c) Load bearing resistance
The load bearing resistance may be calculated for floors where the physical properties are known as a function
of temperature and where the temperature profile over the cross-section of the floor is known. For timber the
charring rate and hence the reduction in cross-section also need to be known.
d) Deflection
The deflection may be calculated for floors where the relationships between stress and strain (including, if
necessary, creep effect) as a function of temperature are known, in addition to the above properties. It should
be noted that the calculated deflection needs to take into account deflections due to both thermal and load
induced strains.
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ISO
3.3.3.3 Judgements
Changes may be made to the following aspects of the floors provided the expert judgement is based on the
appropriate considerations mentioned below.
a) Supporting conditions
The supporting conditions may be changed provided that this will not increase the load effect, reduce the
rotational restraint or change the thermal conditions.
b) Services
Services may be installed into the floor construction provided that this will not reduce the ability of the
construction to satisfy the criteria of loadbearing resistance, insulation, and integrity.
c) Protecting materials
When fire protection materials are changed or increased in order to compensate for changes in the load case
or cross-sectional area, it must be demonstrated (justified) that the connection between the protective material
and the floor will remain effective for a duration sufficient to achieve the fire resistance period.
d) Components
Components of the floor construction may be changed provided it can be shown that this does not reduce the
fire resistance. It must be demonstrated that the interaction of the individual components will not adversely
affect the performance of the tested construction.
e) Change of density
The density of timber components may be changed, subject to the section size being altered to compensate for
the change in charring rate and any associated change in strength.
Change in the density of concrete, beyond that allowed in the rule 3.3.3.1c) can be made provided the influence
of the change in thermal capacity and heat flow is taken into account regarding both the thermal insulation
criteria and the temperature of any supporting elements.
3.4  Walls
3.4.1 General
There are two kinds of walls: separating walls which have to fulfil performance criteria of integrity, insulation and
loadbearing resistance, and walls which do not perform a separating function. The latter have only to meet
performance criteria for loadbearing resistance similar therefore to the clause on columns.
The results from a fire resistance test may be used to support an evaluation of the performance of another
separating wall without any further calculations or the application of rules or judgements if the construction complies
with the guidance given in 3.4.2. Where the construction does not comply with the direct application then the
calculations or application rules or judgements need to be applied as indicated.
The relevant performance criteria are integrity (measured by gap gauge, ignition of cotton pad, or sustained
flaming), insulation (increase of average or maximum temperature) and load bearing resistance (load bearing
capacity: determined by maximum axial contraction and maximum rate of axial contraction).
3.4.2 Direct application
The results of a fire resistance test are deemed to be applicable to a similar type of untested separating wall
provided that all the following are true.
©
ISO
3.4.2.1 Solid part of the wall
a) The height is not increased.
b) The load is not increased, its eccentricity is not increased and the location of the load is unchanged.
c) The edge conditions are unchanged.
d) The thickness is not reduced.
e) Characteristic strength and density of any materials are unchanged.
f) Thermal insulation is not reduced at any point.
g) There is no change in the design of the cross-section (e. g. location of reinforcing bars).
3.4.2.2 Openings in the wall
a) The size of any openings is not increased.
b) The method of protecting the opening (e.g. glazing, door, sealing systems) is not changed.
c) The partition of any opening is unchanged.
3.4.3 Extended application
3.4.3.1 Rules
Rules can be given for the following.
a) Dimensions and loading
Changing the height and load is possible as long as stresses are adjusted accordingly, e.g. the height can be
increased if the load is reduced and vice versa.
b) Slenderness
The slenderness of masonry walls must not exceed X % to prevent buckling failure.
c) Lining materials
Lining or decorative materials not influencing the fire resistance may be changed or added.
3.4.3.2 Fire engineering calculations
Calculations may be used for the following.
a) Temperature profile
Heat transfer through walls may be calculated by using an accepted temperature analysis model. Input data
must be based on values for specific heat capacity and thermal conductivity as a function of temperature for all
materials included in the element. For composite elements it is necessary to estimate, using relevant test
results, the time of exposure at which destruction or detachment of parts of the element (i.e. boards, insulation
etc.) will occur.
b) Insulation performance
Compliance with the insulation criterion may be calculated using appropriate temperature profiles.
©
ISO
c) Load bearing resistance
The load bearing resistance may be calculated for walls where the physical properties are known as a function
of temperature and where the temperature profile over the cross-section of the wall is known.
d) Deformation
The deformation (axial and lateral) may be calculated for walls where the relationships between stress and
strain (including, if necessary, creep effect) as a function of temperature are known, in addition to the above
properties. It should be noted that the calculated deformations need to take into account deformations due to
both thermal and load induced strains.
3.4.3.3 Judgements
Changes may be made to the following aspects of the separating walls provided that expert judgement is based on
the appropriate considerations mentioned below.
3.4.3.3.1 Solid part of the wall
a) Boundary conditions
The supporting conditions may be changed provided that this does not increase the load effect, reduce the
rotational restraint or change the thermal conditions.
b) Slenderness
Length may be inceased or cross-sectional area may be reduced if it is compensated for by an improvement of
the boundary conditions in order to have the same slenderness ratio.
c) Services
Services (doors, ducts, penetrations) may be installed in the wall construction provided that this does not
reduce the ability of the construction to satisfy the criteria of loadbearing resistance, insulation and integrity.
d) Protecting materials
When fire protection materials are changed or increased in order to compensate for changes in the load case
or cross-sectional area, it must be demonstrated (justified) that the connection between the protective material
and the wall will remain effective for a duration sufficient to achieve the fire resistance period.
e) Components
Components of the wall construction may be changed provided it can be shown that this does not reduce the
fire resistance. It must be demonstrated that the interaction of the individual components will not adversely
affect the performance of the tested construction.
f) Joint materials
Joint materials and systems may be changed provided the changes do not affect insulation or integrity.
3.4.3.3.2 Openings in partition
The size, shape and position of any opening may be varied subject to it being demonstrated that there is no adverse
effect on the performance of the partition, e.g. the revised shape does not change the stiffness of the partition and
the revised position does not cause different pressure conditions to exist which may influence integrity. The method
of protecting the opening shall satisfy the fire requirement at the revised size, shape or position; see the relevant
sections of this Technical Report for guidance on the extended application for the appropriate components.
©
ISO
4  Non-loadbearing elements
4.1  Vertical partitions
4.1.1 General
The results from a fire resistance test may be used to support an evaluation of the performance of another vertical
partition without any further calculations or the application of rules or judgements if the construction complies with
the guidance given in 4.1.2. Where the construction does not comply with the direct application then the calculations
or application rules or judgements need to be applied as indicated.
The relevant per
...

SLOVENSKI STANDARD
01-september-1999
Preskusi požarne odpornosti – Navodila za širšo uporabo rezultatov
Fire-resistance tests -- Guidance on the application and extension of results
Essais de résistance au feu -- Recommandations pour l'application et l'extrapolation des
résultats
Ta slovenski standard je istoveten z: ISO/TR 12470:1998
ICS:
13.220.50 Požarna odpornost Fire-resistance of building
gradbenih materialov in materials and elements
elementov
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL ISO/TR
REPORT 12470
First edition
1998-07-15
Fire resistance tests — Guidance on the
application and extension of results
Essais de résistance au feu — Recommandations pour l’application et
l’extrapolation des résultats
A
Reference number
Contents Page
1  Scope . 1
2  Common factors . 2
2.1  Manufacture and materials . 2
2.2  Moisture content. 3
2.3  Increasing size. 4
3  Loadbearing elements. 4
3.1  Beams . 4
3.2  Columns . 6
3.3  Floors. 8
3.4  Walls . 10
4  Non-loadbearing elements. 13
4.1  Vertical partitions . 13
4.2  Ceiling membranes (Horizontal partitions). 15
4.3  Doors - Hinged and pivoted leaves. 16
4.4  Lift landing doors — Centre opening and two-speed lift
landing doors. 21
4.5  Rolling shutters . 24
4.6  Glazed elements . 27
5  Components contributing to the fire resistance of elements . 30
5.1  Suspended ceilings. 30
5.2  Insulating systems . 33
6  Service installations . 35
6.1  Ducts. 35
6.2  Dampers . 38
6.3  Penetration seals. 40
©  ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet [e-mail]
Printed in Switzerland
ii
©
ISO ISO/TR 12470:1998(E)
7  Future evolution. 42
7.1  Improvement of testing methodologies . 42
7.2  Mathematical modelling of thermal
and mechanical response. 44
7.3  Expert system based upon the use of performance
coefficients. 46
Annex A: Summary of general practices in various countries
as far as interpolation and extrapolation are concerned. 49
Annex B: Current practices in various countries . 53
Annex C: Bibliography . 59
iii
©
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.
The main task of technical committees is to prepare International
Standards, but in exceptional circumstances a technical committee may
propose the publication of a Technical Report of one of the following types:
— type 1, when the required support cannot be obtained for the
publication of an International Standard, despite repeated efforts;
— type 2, when the subject is still under technical development or where
for any other reason there is the future but not immediate possibility of
an agreement on an International Standards;
— type 3, when a technical committee has collected data of a different
kind from that which is normally published as an International Standard
(“state of the art”, for example).
Technical Reports of types 1 and 2 are subjected to review within three
years of publication, to decide whether they can be transformed into
International Standards. Technical Reports of type 3 do not necessarily
have to be reviewed until the data they provide are considered to be no
longer valid or useful.
ISO/TR 12470, which is a Technical Report of type 2, was prepared by
Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 2, Fire
resistance.
The primary objective of this Technical Report is to produce a harmonized
approach to the extension of results obtained from fire resistance tests
performed according to the time-temperature curve as given in ISO 834-1.
Such an approach is usable by writers of fire testing standards to assist
with the preparation of harmonized “field of direct application” statements.
In addition it is of assistance to fire safety engineers/consultants who either
need to establish the extended field of application of a tested construction,
to establish whether a similar untested element would be expected to
satisfy the test criteria where the variations between the tested and
untested constructions are significant, or produce the rules governing the
application.
iv
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ISO ISO/TR 12470:1998(E)
The guidance as to whether the application can be extended is given in
three forms. In the simplest form a rule may be used which may be based
upon sound scientific facts or even just custom and practice. For
quantifiable aspects it identifies where fire engineering calculations may be
used. Where judgement needs to be exercised, it identifies the factors that
need to be considered. The guidance given also allows a designer or the
enforcing authority to assess the fire resistance of an element when it is of
a size that cannot be tested due to the physical limitations of testing
furnaces. Whether this is a valid use of this guidance document will depend
upon the philosophy of a particular country's regulations and the way they
use fire resistance tests in their building codes. In a complex building
where the behaviour can only be established from first principles, a greater
understanding of the limitations applying to a test result is critical.
Structural elements such as beams, girders, columns and floors are
generally designed by using calculation methods applicable at room
temperature and each element is more or less different from one another.
These structural elements also need calculation methods that assess their
fire behaviour and it is important that these are correlated by tests.
Annex A forms an integral part of this Technical Report. Annexes B and C
are for information only.
v
©
Introduction
Fire resistance tests on building components are necessary to establish
their behaviour against pre-determined criteria when exposed to a
representative fully developed fire and to provide information that may be
used in determining the fire safety level of buildings. For several decades
people have accepted by means of test results only, the possibility of
grading the components. Now, due to the improvement of knowledge and
the sophistication of buildings, it is necessary to be able to give a more
accurate assessment of the components used in buildings.
Because of the cost of the tests and the size limitations of the testing
furnaces, it is not possible for any given building element to be tested at all
of its various sizes or designs. As a consequence we need rules or even
better mathematical models for predicting, from test results, the behaviour
of elements which are changed in size, design and/or application. The
performance of these elements is adjudged as a separate consideration
and only against standard heating conditions as defined in ISO 834-1.
Even with the knowledge available to assess the behaviour of a given
constructional element, whatever its design or its size, we will still be a long
way from establishing the real behaviour of a building in a real fire.
The philosophy of only grading elements into different fire resistance
categories may not give any indication about how the element behaves
when heated. By studying and assessing the data from fire resistance
tests, it will be possible, using the guidance within this Technical Report, to
obtain a basic understanding of the influence of the main parameters on
the element performance during a fire resistance test.
In practice, tests can give much useful information which can be used for
interpolation and extrapolation of the results.
In the following, all of these assessments will be based on the one hand on
the standard time/temperature conditions and, on the other hand, on
isolated elements with no interaction with the adjacent elements.
Also ageing and weathering are not covered here.
This Technical Report is divided in two parts:
— guidance on direct use and extended application of test results for
various elements used in buildings; the parameters which would be
assessed by rules, calculation or only expert judgements are dis-
cussed.
— future evolution:
• improvement of testing methodologies to give a better prediction
of the performance of various sizes and designs of a given
element,
vi
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ISO ISO/TR 12470:1998(E)
• mathematical modelling which can be used by experts to give
their judgement,
• expert systems which could take into account the interaction of
various factors in an assessment.
In addition annexes A and B give an overview of current practices in
various countries as far as application and extension of fire resistance test
results are concerned. It is mentioned where agreement could be found
and where more efforts have to be made for harmonization.
Annex C gives additional reading.
vii
©
TECHNICAL REPORT  ISO ISO/TR 12470:1998(E)
Fire resistance tests — Guidance on the application and
extension of results
1  Scope
Direct and extended applications of test results are the two possible ways to ensure that a modified element will
have a good possibility of obtaining the same fire rating as that of the original tested specimen. In both cases these
applications refer only to the fire rating that the building element can expect to reach if it were to be tested in a
furnace according to the standard fire used for the reference test.
For each type of element of construction, the application of test results will be considered under two sub-headings.
a) Direct application: this section identifies the modifications that can be made to the design of the tested element
without reducing its fire rating. These possible modifications are based on obvious knowledge and do not need
further evaluation. In every case it is, at least, assumed that the basic materials used for the tested sample will
not be changed. The results obtained from tests performed using standard configurations are valid for the field
of application derived from that configuration, regardless of any specific advice given in the following chapters.
b) Extended application: this will require in every case an assessment by a fire expert either in developing rules of
application or evaluating the results of fire engineering calculations or making a judgement. In every case it will
be taken into consideration that extended application may take into account the difference between the result of
the original test and the fire resistance required for the untested element.
A judgement is the result of a qualitative process, normally carried out by experts. Judgements are used to
justify a change of design or method of construction which may use, for example, empirical data derived from
tests, established physical properties, hot and cold state calculations, a knowledge of fire exposure, fire
behaviour and response of the construction, either in isolation or in combination.
1) Rules of application: these would be applied universally even by persons without expertise in fire as part of
the "field of application" of the test result for a given family of products. These rules may require cold state
calculation. The quantification of these rules would be agreed universally based upon validated experience
related to generic constructions or components. This could cover size changes, number of joints, size of
glazing etc.
Throughout this Technical Report the clauses covering rules frequently express the acceptable change in
terms of un-quantified percentages indicated by the letter "X" and an appropriate suffix.
This allows national code authorities to insert their own acceptable limits which will relate to their
established fire safety philosophy.
Authorities are encouraged to support the necessary research towards internationally harmonized
validated value.
2) Fire engineering calculations: these would be used by an expert in giving advice but will mainly be
restricted to the properties indicated below:
©
ISO
• non-loaded elements: this would be restricted to the calculation of temperature rise and deflection of
"simple" components and elements;
• loaded element: in addition to the properties permitted for non-loaded elements, calculation at
elevated temperature could be permitted for the load-bearing capacity for well-documented materials
(steel, concrete, etc.) and for statically determined elements.
In every case the calculation models used by the experts, whatever their source (purchased from software
manufacturers or developed in the institution) have to be fully validated by comparison with existing test
results and by sensitivity analysis of the various parameters.
3) judgements: for a test result to be extrapolated to cover changes outside those for which calculations or
written rules are applicable, the result may still apply subject to some expert judgement being made. The
section on judgements highlights the matters that need to be considered and to be explained by the body
or person responsible for making such judgements. Generally, components of a construction element
could be changed, provided it can be shown that this does not reduce the fire resistance. It must be
demonstrated that the interaction of a new component with other components will not affect adversely the
performance of the tested construction. When resistance time is higher than required time, it will generally
be possible to have a greater change than with only the necessary safety level.
Changes in materials and methods of construction can have significant influences on the fire resistance. Because
the advice and recommendations are common to all elements, those aspects are dealt with separately under 2.1.1
"manufacture and materials" to avoid repetition. The user of this Technical Report should consider these aspects in
all applications of results whether direct or extended.
2  Common factors
The advice in this clause applies to all subsequent groups of elements.
2.1  Manufacture and materials
2.1.1 General
For certain applications, even small changes in either the materials or the methods of manufacturing may result in
large changes in fire resistance (for example glazing, intumescent coatings, primers). The results from a fire
resistance test may be used to support an evaluation of the performance of a similar untested element or they may
be used to justify an element in use without any further calculations, or the application of rules, if the manufacture of
the element complies with the guidance given in 2.1.2. Where the construction is not covered by the direct
application then the calculations or application rules need to be applied as indicated.
Additionally there are quality control and certification schemes in some countries. Control procedures ensure that
the untested construction is equivalent to the tested construction. Any relaxation of these procedures may only be
undertaken if it can be established that they only influence non-critical aspects of the construction (e.g. colour,
texture, etc.) Evidence of the effect must be available if the control of the 'critical' processes or materials is involved.
Reduced scale fire resistance tests may be used for this purpose subject to the changes not affecting distortion.
The information given for direct and extended applications has to be used for every construction element.
2.1.2 Direct application
a) The quality control procedures are not reduced.
b) The manufacturing/construction procedures remain unchanged.
c) Constituent materials, admixtures, preservatives, flame retardants, adhesives, etc. remain unchanged.
©
ISO
2.1.3 Extended application
2.1.3.1 Rules
As a general rule the quantity of any constituent material may be varied by up to a certain percentage (to be defined
for each family of material) from that used in the original specification that was tested without the need for further
consideration.
2.1.3.2 Fire engineering calculations
Where, for certain materials, calculation methods have evolved and been documented it may be possible to
calculate the influence that changes in material and manufacturing may have on the fire resistance.
2.1.3.3 Judgements
a) Materials
It may be possible to change constituent materials, or add constituents such as preservatives or flame retardants
without significantly affecting the fire resistance. Evidence of the effect that this may have should be available or its
effect should be able to be calculated to demonstrate that these changes will not reduce the fire resistance.
Reduced scale fire resistance tests may be suitable for this purpose. If the additional constituents may be expected
to influence distortion patterns, then a full scale test may be required.
b) Manufacturing procedures
The effect of any change in the manufacturing procedure shall be established to show that it does not reduce the
fire resistance of the element before such changes are accepted.
2.2  Moisture content
Since it is difficult to measure the moisture content of many elements prior to the test, it is better to try to reach an
equilibrium before testing. However when for various reasons this is not possible and if information is available on
the assumed moisture content, the following correction can be used.
If the fire resistance with respect to insulation criterion of a specimen is known at one moisture content, then the
1)
insulation rating at some other moisture content can be corrected according to the following equation :
TT++()4 bf-T-40T=
dd ff
where
f is the volumetric moisture content,
T is the fire resistance, in minutes, of the element at a moisture content of f,
f
T is the fire resistance, in minutes, of the element in oven-dry condition,
d
b is a factor, in minutes, which varies with the permeability.
This formula can be used for correcting the insulation criteria relating to a homogeneous structural element such as
concrete slabs, brick walls, with some limits of application. It is not applicable to timber and gypsum products.

1)  T.Z. HARMATHY, "Fire Safety Design and Concrete". Longman Scientific & Technical, 1993.
©
ISO
2.3  Increasing size
A non-loadbearing separating element having obtained a given fire rating could be used for a lower fire rating
application at a bigger size than that allowed in an application requiring the obtained fire rating. The reason for this
is that to achieve a better performance than that required it is necessary to produce a more stable element to
ensure reduced distortion and/or deformation and hence less erosion of any constitutive materials.
3  Loadbearing elements
In practice few structural elements are covered by direct application because there is always a difference in size or
strength of material used.
For protected load bearing elements, please refer also to 5.2.
For simple elements, it is normal to use design codes which take fire into account.
3.1  Beams
3.1.1 General
The results from a fire resistance test may be used to support an evaluation of the performance of another beam
without any further calculations or the application of rules or judgements if the construction complies with the
guidance given in 3.1.2. Where the construction does not comply with the direct application, then the calculations or
application rules or judgements need to be applied as indicated.
The relevant performance criterion is the loadbearing resistance (loadbearing capacity: determined by maximum
deflection and maximum rate of deflection).
3.1.2 Direct application
The results of a fire resistance test are deemed to be applicable to a similar untested beam provided that all the
following are true.
a) The span is not increased.
b) The load is not increased and the location and distribution of the load are unchanged.
c) The rotational and longitudinal restraint are unchanged.
d) The dimensions of the cross-section are not reduced.
e) Characteristic strength and density of any basic materials are unchanged.
f) The number of heated surfaces is unchanged.
g) The length of the unheated part of the construction is not reduced.
h) There is no change in the design of the cross-section (e. g. reinforcing bars within the cross-section).
i) Lining or decorative materials not influencing the fire resistance may be changed or added.
3.1.3 Extended application
3.1.3.1 Rules
Rules can be given for the following.
©
ISO
a) Dimensions and loading (length of span, level and type of load)
The length and load (level and distribution) may be changed as long as it can be calculated that the stresses
(bending and shearing) within the section are not increased, and providing that failure mode at room
temperature does not change (the span could be increased if the load is reduced and vice versa).
b) Reinforcement for reinforced concrete beams (not relevant for prestressed concrete beams)
A change in the location of reinforcement is possible as long as its temperature is not increased, the total cross-
section is not reduced, and the distance between the reinforcement and the centroid of the compressive zone is
not reduced.
c) Number of heated surfaces
The number of heated surfaces may be reduced for beams made of materials where this is not detrimental to
the performance.
d) Services
Holes for services may be incorporated if they are perpendicular to the span and in the zone of the neutral axis,
provided that they are protected at their borders in the same way as the beam itself.
e) Lining materials
Lining or decorative materials not influencing the fire resistance may be changed or added.
3.1.3.2 Fire engineering calculations
Calculations may be used for the following.
a) Temperature profile
Heat transfer through beams may be calculated by using an accepted temperature analysis model. Input data
must be based on values for specific heat capacity and thermal conductivity as a function of temperature for all
materials included in the element. For composite elements it is necessary to estimate, using relevant test
results, the time of exposure at which destruction or detachment of parts of the element (i.e. boards, insulation
etc.) will occur.
b) Load bearing resistance (load bearing capacity)
The load bearing resistance may be calculated for beams where the physical properties are known as a
function of temperature and where the temperature profile over the cross-section of the beam is known. For
timber the charring rate and hence the reduction in cross-section also need to be known.
c) Deflection
The deflection may be calculated for beams where the relationships between stress and strain (including, if
necessary, creep effect) as a function of temperature are known, in addition to the above properties. It should
be noted that the calculated deflections need to take into account deflections due to both the thermal and load
induced strains.
3.1.3.3 Judgements
Changes may be made to the following aspects of the beams provided that expert judgement is based on the
appropriate considerations mentioned below.
a) Supporting conditions
The supporting conditions may be changed, provided that this will not increase the load effect, reduce the
rotational restraint, or increase the longitudinal restraint or the thermal conditions.
©
ISO
b) Protecting materials
When fire protection materials are changed or increased in order to compensate for changes in the load case
or cross-sectional area, it must be demonstrated (justified) that the connection between the protective material
and the beam will remain effective for a duration sufficient to achieve the fire resistance period.
c) Heated surfaces
The number and area of heated surfaces can be increased, if it can be demonstrated that in increasing the
height of the cross-section or decreasing the perimeter/area ratio (for instance) the load bearing resistance is at
least the same as the resistance of the tested beam.
d) Components
Components of the beam construction (additional support for floors or the other beams) can be added, provided
that it can be shown that this does not reduce the fire resistance.
e) Services
Holes in beams perpendicular to their span may be allowed provided the stresses (bending and shear) at the
location of the holes do not exceed the corresponding maximum stresses in the tested beam and the holes are
protected at their edges in order to avoid excessive increase of temperature.
f) Protecting holes
Where holes are made in a beam which is protected, it is necessary for the boundary of the hole to be provided
with an equivalent level of protection.
3.2  Columns
3.2.1 General
The results from a fire resistance test may be used to support an evaluation of the performance of another column
without any further calculations or the application of rules or judgements if the construction complies with the
guidance given in 3.2.2. Where the construction does not comply with the direct application then the calculations or
application rules or judgements need to be applied as indicated.
The relevant performance criterion is the loadbearing resistance (loadbearing capacity: determined by maximum
axial contraction and maximum rate of axial contraction).
3.2.2 Direct application
The results of a fire resistance test are deemed to be applicable to a similar untested column provided that all the
following are true.
a) The length is not increased.
b) The load is not increased and its eccentricity is not increased.
c) The end conditions are unchanged.
d) The dimensions of the cross-section are not reduced.
e) Characteristic strength and density of any basic materials are unchanged.
f) The number of heated surfaces is unchanged.
g) There is no change in the design of the cross-section (e. g. reinforcing bars within the cross-section).
©
ISO
3.2.3 Extended application
3.2.3.1 Rules
Rules can be given for the following.
a) Dimensions (including length), loading and end conditions
The length, slenderness and load may be changed as long as it can be calculated that the load level is not
increased, e.g. the length can be increased if the load is reduced or the end conditions result in a lower
slenderness ratio and vice versa.
b) Reinforcement for reinforced concrete columns (not applicable to prestressed concrete)
A change in the location of reinforcement is possible as long as its temperature is not increased, there is no
bending moment and the total cross-section is not reduced.
c) Services
Holes with a diameter less than or equal to X for services in concrete columns are allowed where the
thickness of the material on both sides of the hole has a minimum of X . The hole shall not remove any
reinforcement.
d) Lining materials
Lining or decorative materials not influencing the fire resistance may be changed or added.
3.2.3.2 Fire engineering calculations
Calculations may be used for the following.
a) Temperature profile
Heat transfer through columns may be calculated by using an accepted temperature analysis model. Input data
must be based on values for specific heat capacity and thermal conductivity as a function of temperature for all
materials included in the element. For composite elements it is necessary to estimate, using relevant test
results, the time of exposure at which destruction or detachment of parts of the element (i.e. boards, insulation
etc.) will occur.
b) Load bearing resistance
The load bearing resistance may be calculated for columns where the physical properties are known as a
function of temperature and where the temperature profile over the cross-section of the column is known. For
timber the charring rate and hence the reduction in cross-section also need to be known.
c) Deformation
The deformation (axial and lateral) may be calculated for columns where the relationships between stress and
strain (including, if necessary, creep effect) as a function of temperature are known, in addition to the above
properties. It should be noted that the calculated deformation needs to take into account deformations due to
both thermal and load induced strains.
d) Services
Holes for services in concrete columns or holes in columns of material other than concrete, perpendicular to the
length, are allowed if it can be calculated that they do not reduce the load bearing resistance at elevated
temperature.
©
ISO
3.2.3.3 Judgements
Changes may be made to the following aspects of the columns provided the expert judgement is based on the
appropriate considerations mentioned below.
a) Supporting conditions
The supporting conditions may be changed, provided that this will not increase the load effect or reduce the
rotational or the thermal conditions.
b) Protecting materials
When fire protection materials are changed or increased in order to compensate for changes in the load case
or cross-sectional area, it must be demonstrated (justified) that the connection between the protective material
and the column shall remain effective for a duration sufficient to achieve the fire resistance period.
c) Components
Components of the column (brackets etc.) can be added, provided that it can be shown that this does not
reduce the fire resistance.
d) Protecting holes
Where holes are made in a column which is protected, it is necessary for the boundary of the hole to be
provided with an equivalent level of protection.
3.3  Floors
3.3.1 General
The results from a fire resistance test may be used to support an evaluation of the performance of another floor
without any further calculations or the application of rules or judgements if the construction complies with the
guidance given in 3.3.2. Where the construction does not comply with the direct application then the calculations or
application rules or judgements need to be applied as indicated.
The relevant performance criteria are integrity (measured by gap gauge, ignition of cotton pad, or sustained
flaming), insulation (increase of average or maximum temperature) and loadbearing resistance (loadbearing
capacity: determined by maximum deflection and maximum rate of deflection).
3.3.2 Direct application
The results of a fire resistance test are deemed to be applicable to a similar untested floor, provided that all the
following are true.
a) The span is not increased and, in the case of a two-way spanning floor, the span ratio is unchanged.
b) The load is not increased and the location and distribution of the load are unchanged.
c) The rotational and longitudinal restraint are unchanged.
d) The thickness is not reduced.
e) Characteristic strength and density of any basic materials are unchanged.
f) Thermal insulation is not reduced at any point over the whole area.
g) The length of unheated parts of the construction is not reduced.
h) There is no change in the design of the cross section (e. g. the location of reinforcing bars).
©
ISO
3.3.3 Extended application
3.3.3.1 Rules
Rules can be given for the following.
a) Dimensions
The width of the floor can be increased provided sufficient space is allowed at the edges to permit the
increased thermal expansion without leading to system failure.
b) Dimensions and loading
The span can be increased provided the load is reduced or the load can be increased provided the span is
reduced. The changes to the loading or the span must not increase stress levels within the section in excess of
the design stresses associated with the fire design load case.
Any changes to the loading or the span must not change the mode of failure.
If the thickness of the floor is reduced corresponding to a reduction in the load in order to maintain the same
stress levels, the thickness may not be reduced to such an extent that the floor will not provide adequate
insulation.
c) Change in density
Where light weight concrete is substituted for normal weight concrete, the thickness of the slab may be reduced
by X % in respect of the insulation criterion as long as the loadbearing capacity is satisfactory. The temperature
of steel beams and the temperature of steel floors in contact with the concrete will increase when light weight
concrete replaces normal weight concrete.
d) Lining materials
Lining or decorative materials not influencing the fire resistance may be changed or added.
3.3.3.2 Fire engineering calculations
Calculations may be used for the following.
a) Temperature profile
Heat transfer through floors may be calculated by using an accepted temperature analysis model. Input data
must be based on values for specific heat capacity and thermal conductivity as a function of temperature for all
materials included in the element. For composite elements it is necessary to estimate, using relevant test
results, the time of exposure at which destruction or detachment of parts of the element (i.e. boards, insulation
etc.) will occur.
b) Insulation performance
Compliance with the insulation criterion may be calculated using appropriate temperature profiles.
c) Load bearing resistance
The load bearing resistance may be calculated for floors where the physical properties are known as a function
of temperature and where the temperature profile over the cross-section of the floor is known. For timber the
charring rate and hence the reduction in cross-section also need to be known.
d) Deflection
The deflection may be calculated for floors where the relationships between stress and strain (including, if
necessary, creep effect) as a function of temperature are known, in addition to the above properties. It should
be noted that the calculated deflection needs to take into account deflections due to both thermal and load
induced strains.
©
ISO
3.3.3.3 Judgements
Changes may be made to the following aspects of the floors provided the expert judgement is based on the
appropriate considerations mentioned below.
a) Supporting conditions
The supporting conditions may be changed provided that this will not increase the load effect, reduce the
rotational restraint or change the thermal conditions.
b) Services
Services may be installed into the floor construction provided that this will not reduce the ability of the
construction to satisfy the criteria of loadbearing resistance, insulation, and integrity.
c) Protecting materials
When fire protection materials are changed or increased in order to compensate for changes in the load case
or cross-sectional area, it must be demonstrated (justified) that the connection between the protective material
and the floor will remain effective for a duration sufficient to achieve the fire resistance period.
d) Components
Components of the floor construction may be changed provided it can be shown that this does not reduce the
fire resistance. It must be demonstrated that the interaction of the individual components will not adversely
affect the performance of the tested construction.
e) Change of density
The density of timber components may be changed, subject to the section size being altered to compensate for
the change in charring rate and any associated change in strength.
Change in the density of concrete, beyond that allowed in the rule 3.3.3.1c) can be made provided the influence
of the change in thermal capacity and heat flow is taken into account regarding both the thermal insulation
criteria and the temperature of any supporting elements.
3.4  Walls
3.4.1 General
There are two kinds of walls: separating walls which have to fulfil performance criteria of integrity, insulation and
loadbearing resistance, and walls which do not perform a separating function. The latter have only to meet
performance criteria for loadbearing resistance similar therefore to the clause on columns.
The results from a fire resistance test may be used to support an evaluation of the performance of another
separating wall without any further calculations or the application of rules or judgements if the construction complies
with the guidance given in 3.4.2. Where the construction does not comply with the direct application then the
calculations or application rules or judgements need to be applied as indicated.
The relevant performance criteria are integrity (measured by gap gauge, ignition of cotton pad, or sustained
flaming), insulation (increase of average or maximum temperature) and load bearing resistance (load bearing
capacity: determined by maximum axial contraction and maximum rate of axial contraction).
3.4.2 Direct application
The results of a fire resistance test are deemed to be applicable to a similar type of untested separating wall
provided that all the following are true.
©
ISO
3.4.2.1 Solid part of the wall
a) The height is not increased.
b) The load is not increased, its eccentricity is not increased and the location of the load is unchanged.
c) The edge conditions are unchanged.
d) The thickness is not reduced.
e) Characteristic strength and density of any materials are unchanged.
f) Thermal insulation is not reduced at any point.
g) There is no change in the design of the cross-section (e. g. location of reinforcing bars).
3.4.2.2 Openings in the wall
a) The size of any openings is not increased.
b) The method of protecting the opening (e.g. glazing, door, sealing systems) is not changed.
c) The partition of any opening is unchanged.
3.4.3 Extended application
3.4.3.1 Rules
Rules can be given for the following.
a) Dimensions and loading
Changing the height and load is possible as long as stresses are adjusted accordingly, e.g. the height can be
increased if the load is reduced and vice versa.
b) Slenderness
The slenderness of masonry walls must not exceed X % to prevent buckling failure.
c) Lining materials
Lining or decorative materials not influencing the fire resistance may be changed or added.
3.4.3.2 Fire engineering calculations
Calculations may be used for the following.
a) Temperature profile
Heat transfer through walls may be calculated by using an accepted temperature analysis model. Input data
must be based on values for specific heat capacity and thermal conductivity as a function of temperature for all
materials included in the element. For composite elements it is necessary to estimate, using relevant test
results, the time of exposure at which destruction or detachment of parts of the element (i.e. boards, insulation
etc.) will occur.
b) Insulation performance
Compliance with the insulation criterion may be calculated using appropriate temperature profiles.
©
ISO
c) Load bearing resistance
The load bearing resistance may be calculated for walls where the physical properties are known as a function
of temperature and where the temperature profile over the cross-section of the wall is known.
d) Deformation
The deformation (axial and lateral) may be calculated for walls where the relationships between stress and
strain (including, if necessary, creep effect) as a function of temperature are known, in addition to the above
properties. It should be noted that the calculated deformations need to take into account deformations due to
both thermal and load induced strains.
3.4.3.3 Judgements
Changes may be made to the following aspects of the separating walls provided that expert judgement is based on
the appropriate considerations mentioned below.
3.4.3.3.1 Solid part of the wall
a) Boundary conditions
The supporting conditions may be changed provided that this does not increase the load effect, reduce the
rotational restraint or change the thermal conditions.
b) Slenderness
Length may be inceased or cross-sectional area may be reduced if it is compensated for by an improvement of
the boundary conditions in order to have the same slenderness ratio.
c) Services
Services (doors, ducts, penetrations) may be installed in the wall construction provided that this does not
reduce the ability of the construction to satisfy the criteria of loadbearing resistance, insulation and integrity.
d) Protecting materials
When fire protection materials are changed or increased in order to compensate for changes in the load case
or cross-sectional area, it must be demonstrated (justified) that the connection between the protective material
and the wall will remain effective for a duration sufficient to achieve the fire resistance period.
e) Components
Components of the wall construction may be changed provided it can be shown that this does not reduce the
fire resistance. It must be demonstrated that the interaction of the individual components will not adversely
affect the performance of the tested construction.
f) Joint m
...

RAPPORT ISO/TR
TECHNIQUE 12470
Première édition
1998-07-15
Essais de résistance au feu —
Recommandations pour l'application et
l'extrapolation des résultats
Fire resistance tests — Guidance on the application and extension of
results
A
Numéro de référence
Sommaire
Page
1 Domaine d'application. 1
2 Facteurs communs . 2
2.1 Fabrication et matériaux. 2
2.3 Augmentation de la taille . 3
3 Éléments porteurs. 4
3.1 Poutres . 4
3.2 Poteaux . 6
3.3 Planchers. 8
3.4 Murs. 10
4 Éléments non portants. 12
4.1 Cloisons verticales. 12
4.3 Portes avec vantaux à charnières ou pivotants. 16
4.4 Portes palières d'ascenseurs — Portes palières à ouverture
centrée et à deux vitesses. 21
4.5 Fermetures à enroulement . 24
4.6 Éléments vitrés. 26
5 Composants contribuant à la résistance au feu des éléments . 29
5.1 Plafonds suspendus . 29
5.2 Systèmes de protection. 33
6 Équipements. 35
6.1 Conduits . 35
6.2 Clapets . 37
6.3 Calfeutrements de pénétrations . 39
©  ISO 1998
Droits de reproduction réservés. Sauf prescription différente, aucune partie de cette publi-
cation ne peut être reproduite ni utilisée sous quelque forme que ce soit et par aucun pro-
cédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord
écrit de l'éditeur.
Organisation internationale de normalisation
Case postale 56 • CH-1211 Genève 20 • Suisse
Internet [e-mail]
Imprimé en Suisse
ii
©
ISO ISO/TR 12470:1998(F)
7 Évolution future . 41
7.1 Amélioration des méthodologies d’essai . 41
7.2 Modélisation mathématique de la réponse thermique et
mécanique . 43
7.3 Système d'expert fondé sur l'utilisation de coefficients de
performance.
Annexe A (informative) Résumé des pratiques générales dans
différents pays concernant l'interpolation et l'extrapolation. 48
Annexe B (informative) Pratiques courantes de différents pays. 52
Annexe C (informative) Bibliographie. 58
iii
©
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération
mondiale d'organismes nationaux de normalisation (comités membres de
l'ISO). L'élaboration des Normes internationales est en général confiée aux
comités techniques de l'ISO. Chaque comité membre intéressé par une
étude a le droit de faire partie du comité technique créé à cet effet. Les
organisations internationales, gouvernementales et non gouvernementales,
en liaison avec l'ISO participent également aux travaux. L'ISO collabore
étroitement avec la Commission électrotechnique internationale (CEI) en
ce qui concerne la normalisation électrotechnique.
La tâche principale des comités techniques est d'élaborer les Normes
internationales. Exceptionnellement, un comité technique peut proposer la
publication d'un rapport technique de l'un des types suivants:
— type 1, lorsque, en dépit de maints efforts, l'accord requis ne peut
être réalisé en faveur de la publication d'une Norme internationale;
— type 2, lorsque le sujet en question est encore en cours de
développement technique ou lorsque, pour toute autre raison, la
possibilité d'un accord pour la publication d'une Norme internationale
peut être envisagée pour l'avenir mais pas dans l'immédiat;
— type 3, lorsqu'un comité technique a réuni des données de nature
différente de celles qui sont normalement publiées comme Normes
internationales (ceci pouvant comprendre des informations sur l'état
de la technique, par exemple).
Les rapports techniques des types 1 et 2 font l'objet d'un nouvel examen
trois ans au plus tard après leur publication afin de décider éventuellement
de leur transformation en Normes internationales. Les rapports techniques
du type 3 ne doivent pas nécessairement être révisés avant que les
données fournies ne soient plus jugées valables ou utiles.
L'ISO/TR 12470, rapport technique du type 2, a été élaboré par le comité
technique ISO/TC 92, Sécurité au feu, sous-comité SC 2, Résistance au
feu.
L'objectif premier du présent Rapport technique est de définir une appro-
che harmonisée pour l'extrapolation des résultats des essais de résistance
au feu effectués selon la courbe temps/température de l'ISO 834-1. Les
rédacteurs des normes d'essais au feu peuvent utiliser cette approche
pour la préparation de «domaines harmonisés d'application directe». De
plus, cette approche peut aider les ingénieurs/consultants en sécurité
incendie qui, soit ont besoin d'étendre le champ d'application directe d'un
élément de construction soumis à essai à des éléments similaires non
soumis à essai pour déterminer s'ils sont susceptibles de satisfaire aux
critères d'essai lorsqu'il existe des changements notables entre les
éléments de constructions soumis à essais et ceux non soumis à essais,
soit établissent les règles d'application.
iv
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ISO ISO/TR 12470:1998(F)
Ces recommandations concernant les conditions d'extension des résultats
peuvent prendre trois formes. Sous la forme la plus simple, une règle
découlant de faits scientifiques prouvés ou même juste basée sur les
coutumes et pratiques peut être utilisé. Pour des aspects quantifiables,
elles indiquent les calculs relatifs à l'ingénierie de l'incendie qui peuvent
être utilisés. Lorsqu'un avis doit être porté, elles indiquent les facteurs à
prendre en considération. Les recommandations permettent aussi au
concepteur ou aux autorités compétentes d'évaluer la résistance au feu
d'un élément dont la dimension empêche de le soumettre aux essais de
par les limitations physiques des fours utilisés. La validité de ce document
dépendra de la philosophie des règlements de chaque pays et de la
manière dont ceux-ci utilisent les essais de résistance au feu dans leurs
codes de construction. Pour un bâtiment complexe, dont le comportement
au feu peut être établi seulement à partir de principes premiers, il est
crucial de mieux comprendre les limitations qui s'appliquent aux résultats
des essais.
Les éléments de construction tels que les poutres, les fermes, les colonnes
et les planchers sont généralement dimensionnés en utilisant des
méthodes applicables à température ambiante et les éléments sont plus ou
moins différents les uns des autres. Ils doivent également disposer de
méthode pour évoluer leur comportement au feu et il est important que ces
méthodes soient corrélées à des essais.
L'annexe A fait partie intégrante du présent Rapport technique. Les
annexes B et C sont données uniquement à titre d'information.
v
©
Introduction
Les essais de résistance au feu effectués sur les éléments de construction
servent à déterminer le comportement de ces composants en fonction de
critères prédéterminés lorsqu'ils sont exposés à un feu développé et
représentatif; les essais fournissent également des informations qui
peuvent être utilisées pour déterminer le niveau de sécurité incendie des
bâtiments. Pendant des décennies, on a accepté la possibilité de classer
les composants en se basant uniquement sur les résultats des essais.
Aujourd'hui, avec l'amélioration des connaissances et la sophistication des
bâtiments, il est nécessaire de pouvoir donner une évaluation plus précise
des composants utilisés dans un bâtiment.
Etant donné le coût des essais et la limitation en taille des fours à essais, il
est impossible d'essayer toutes les variantes et toutes les différentes
dimensions d'un élément. En conséquence, nous avons besoin de règles,
ou mieux encore, de modèles mathématiques pour prévoir d'après les
résultats des essais, le comportement d'éléments dont la taille, la
conception et/ou l'utilisation différent. La performance de ces éléments est
jugée en dehors de toute autre considération et uniquement par rapport
aux conditions normalisées d'échauffement définies par l'ISO 834-1.
Mais, même en ayant la connaissance nécessaire à l'évaluation du
comportement d'un élément de construction donné quelle que soit sa
conception ou sa taille, nous serons encore loin de pouvoir établir le
comportement réel d'un bâtiment dans un incendie réel.
La philosophie qui consiste uniquement à classer les éléments en degrés
de résistance au feu peut ne donner aucune indication sur la façon dont
l'élément se comporte lorsqu'il est échauffé. En étudiant et en évaluant les
résultats des essais de résistance au feu, il sera possible en utilisant les
recommandations du présent Rapport technique d'avoir une compréhen-
sion de base de l'influence qu'ont les principaux paramètres sur la
performance de l'élément pendant un essai de résistance au feu.
Dans la pratique, les essais peuvent fournir des informations très utiles qui
peuvent être utilisées pour l'interpolation et l'extrapolation des résultats.
Dans la suite de ce document, toutes les évaluations se fonderont d'une
part sur les conditions temps-température normatives, et d'autre part sur
des éléments isolés sans interaction avec les éléments voisins.
Le vieillissement et la désagrégation dues aux intempéries ne sont pas
traités dans le présent Rapport technique.
Le présent rapport est divisé en deux parties:
— un guide d'utilisation directe et d'application étendue des résultats des
essais effectués sur différents éléments utilisés dans les bâtiments; le
mode d'évaluation des paramètres par règles, calculs ou uniquement
par avis d'experts est indiqué;
vi
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ISO ISO/TR 12470:1998(F)
— l'évolution future:
• amélioration des méthodologies d'essais de manière à mieux
prévoir les performances d'éléments donnés dans leurs
différentes dimensions et conceptions,
• modélisation mathématique pouvant être utilisée par les experts
pour asseoir leur avis,
• systèmes experts qui pourraient prendre en compte l'interaction
de différents facteurs dans une évaluation.
De plus, les annexes A et B donnent un panorama des pratiques courantes
dans différents pays en matière d'application et d'extension des résultats
des essais de résistance au feu. Il y est fait mention des éléments sur
lesquels un accord peut être atteint et de ceux sur lesquels il faudrait faire
plus d'efforts en vue d'une harmonisation.
L'Annexe C donne une littérature supplémentaire.
vii
©
RAPPORT TECHNIQUE  ISO ISO/TR 12470:1998(F)
Essais de résistance au feu — Recommandations pour
l'application et l'extrapolation des résultats
1  Domaine d'application
L'application directe et l'application étendue des résultats d'essais constituent les deux manières possibles de
s'assurer qu'un élément modifié aura une forte probabilité d'avoir la même capacité de résistance au feu que
l'échantillon original essayé. Dans les deux cas, ces applications font uniquement référence à la capacité de
résistance au feu que l'élément de construction peut atteindre s'il est essayé dans un four simulant un feu normalisé
utilisé pour l'essai de référence.
Pour chaque type d'élément de construction, l'application des résultats d'essai sera examinée dans deux sections.
a) Application directe: cette section identifie les modifications qui peuvent être apportées dans la conception de
l'élément essayé sans réduire sa capacité de résistance au feu. Ces éventuelles modifications sont fondées sur
une connaissance évidente et ne nécessitent pas d'évaluation plus approfondie. Dans tous les cas, il est au
moins supposé que les matériaux de base utilisés pour l'échantillon soumis à essai ne seront pas modifiés. Les
résultats obtenus à partir des essais effectués sur des configurations normalisées sont valides pour le champ
d'application attaché à cette configuration, quelles que soient les recommandations spécifiques données dans
les chapitres suivants;
b) Application étendue: dans tous les cas, l'application doit être établie par un expert «incendie», soit en
développant des règles d'application, soit en évaluant les résultats de calculs, soit en émettant un avis. Dans
tous les cas, il faut noter le fait que l'application étendue peut également prendre en compte la différence entre
le résultat de l'essai initial et la résistance au feu imposée à l'élément non essayé.
Un avis d'experts résulte d'un processus qualitatif, généralement mené par des experts. Les avis d'experts sont
utilisés pour justifier une modification de conception ou de méthode de construction fondée par exemple sur
des données empiriques provenant d'essais, des propriétés physiques confirmées, des calculs à froid ou à
chaud, une connaissance de l'exposition au feu, du comportement au feu et de la réaction de la construction,
isolée ou en combinaison:
1) Règles d'application: elles sont applicables universellement même par des personnes sans expertise de
l'incendie, en tant que «domaine d'application» du résultat d'essai pour une famille donnée de produits.
Ces règles peuvent nécessiter un calcul à froid. La quantification de ces règles doit faire l'objet d'un accord
général fondé sur des expériences validées liées aux constructions ou composants génériques. Ceci peut
concerner les variations de dimension, le nombre de joints, la dimension d'un vitrage etc.
Tout au long du présent Rapport technique, dans les paragraphes contenant des règles, les modifications
acceptables sont généralement exprimées en terme de pourcentages non quantifiés indiqués par la lettre
«X» suivie d'un suffixe approprié.
Cela permet aux autorités nationales responsables de chaque code d'indiquer leurs propres limites
acceptables fonction de leur concept de sécurité incendie.
Les autorités sont encouragées à soutenir les recherches nécessaires afin d'arriver à une des valeurs
harmonisées au plan international.
2) Calculs de résistance au feu: ils seront utilisés par un expert pour donner des recommandations, mais se
limitent principalement aux propriétés indiquées ci-dessous:
• pour les éléments non chargés, au calcul de l'augmentation de température et de déformation des
composants et des éléments «simples»;
©
ISO
• pour les éléments chargés, outre les propriétés autorisées pour les éléments non chargés, le calcul à
température élevée pour déterminer la capacité portante pour des matériaux sur lesquels on a
suffisamment d'information (acier, béton.) et des éléments isostatiques.
Dans tous les cas, les modèles de calcul utilisés par les experts, quelle que soit leur source (vendus par un
fabricant de logiciels ou développés dans l'entreprise) doivent être complètement validés par comparaison
avec les résultats existants d'essais et par une analyse de sensibilité des différents paramètres:
3) Avis d'experts: l'extrapolation d'un résultat d'essai à des modifications autres que celles pour lesquelles
des calculs ou des règles écrites sont applicables, ne peut se faire qu'après évaluation par un expert. La
section qui traite des avis d'experts met en évidence les points qui doivent être considérés et expliqués par
l'organisme ou la personne responsable devant porter tel ou tel avis. Généralement, il est possible de
modifier un composant d'un élément de construction, à condition qu'il puisse être montré que cette
modification ne réduit pas la résistance au feu de ce dernier. Il faut prouver que l'interaction d'un nouveau
composant avec les autres composants n'affectera pas de manière néfaste la performance de la
construction essayée. Lorsque la durée de résistance est supérieure à la durée requise, il sera
généralement possible de procéder à un changement plus important que lorsque le niveau de sécurité est
juste atteint.
La modification des matériaux et des méthodes de construction peut influer de manière significative sur la
résistance au feu. Puisque les conseils et les recommandations sont communs à tous les éléments, pour éviter la
répétition, ces aspects sont traités séparément en 2.1.1 «fabrication et matériaux». L'utilisateur du présent Rapport
technique devra considérer ces aspects pour toutes les applications, directe ou étendue, des résultats.
2  Facteurs communs
Les conseils donnés dans le présent article s'appliquent à tous les groupes d'éléments énumérés par la suite.
2.1  Fabrication et matériaux
2.1.1  Généralités
Pour certaines applications, des modifications, même peu importantes, soit des matériaux, soit des méthodes de
fabrication peuvent entraîner de grandes variations dans la résistance au feu (par exemple concernant les vitrages,
les primaires d'enduits intumescents). Les résultats d'un essai de résistance au feu peuvent être utilisés pour
appuyer une évaluation de la performance d'un élément similaire, non essayé, pour justifier l'utilisation d'un élément
sans besoins de calculs supplémentaires, ou pour justifier l'application des règles si la fabrication de l'élément
correspond aux recommandations données en 2.1.2. Lorsque l'élément ne fait pas l'objet d'applications directes, les
calculs ou les règles d'application devront alors être utilisés comme indiqué.
De plus, il existe des programmes de contrôle de qualité et de certification dans certains pays. Les procédures de
contrôle assurent que l'élément non essayé est équivalent à l'élément essayé. Un assouplissement quelconque de
ces procédures ne peut être entrepris que s'il peut être établi qu'elles ne portent que sur des aspects peu
importants de l'élément, (par exemple la couleur, la texture, etc.). Si le contrôle des processus «critiques» ou des
matériaux sont impliqués, la preuve doit en être apportée. Des essais de résistance au feu à échelle réduite
peuvent être utilisés dans ce but, à condition que les changements effectués n'affectent pas la déformation.
Les informations données pour les applications directe et étendue doivent être utilisées pour chaque élément de
construction.
2.1.2  Application directe
a) Les procédures de contrôle de la qualité ne sont pas réduites.
b) Les procédures de fabrication/de construction restent les mêmes.
c) Les matériaux constituants, les adjuvants, les agents de conservation, les produits ignifuges, les adhésifs etc.
restent les mêmes.
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2.1.3  Application étendue
2.1.3.1  Règles
En règle générale, il est possible, sans qu'il soit besoin de l'évaluer davantage, de faire varier la quantité de
matériau constituant jusqu'à un certain pourcentage (à définir pour chaque famille de matériau) par rapport à ce qui
est utilisé dans la spécification originale qui a été essayée .
2.1.3.2  Calculs de résistance au feu
Lorsque pour certains matériaux les méthodes de calculs ont évolué et ont été documentées, il est possible de
calculer l'influence que les modifications de matériau et de fabrication peuvent avoir sur la résistance au feu.
2.1.3.3  Avis d'experts
a) Matériaux
Il peut être possible de changer les matériaux constituants, ou d'ajouter des constituants comme des agents de
conservation ou des matériaux ignifuges sans affecter de manière significative la résistance au feu. Il faut
pouvoir présenter des preuves sur l'effet que cela peut avoir ou les effets peuvent être estimés par calcul, afin
de démontrer que ces changements ne réduiront pas la résistance au feu. Les essais de résistance au feu à
de
échelle réduite peuvent convenir ici. Si l'on s'attend à ce que le constituant ajouté modifie les profils
déformation, un essai en grandeur réelle peut être nécessaire.
b) Modes de fabrication
Les effets de toute modification du mode de fabrication doivent être établis pour montrer, avant que ces
modifications ne soient acceptées, qu'elles ne réduisent pas la résistance au feu de l'élément.
2.1.2  Teneur en humidité
Puisqu'il est difficile de mesurer la teneur en humidité de beaucoup d'éléments avant de les soumettre à l'essai, il
est préférable d'essayer d'atteindre l'équilibre auparavant. Néanmoins, lorsque pour différentes raisons, cela n'est
pas possible et que l'on connaît la teneur supposée en humidité, la correction suivante peut être utilisée.
Si l'on connaît la résistance au feu d'un échantillon par rapport au critère d'isolation thermique à une teneur donnée
en humidité, on peut alors corriger la capacité d'isolation pour une autre teneur en humidité à l'aide de l'équation
1)
suivante :
� �
TT++�4 bf-T�-40T=
dd ff
Ł ł
où
f est la teneur volumique en humidité;
T est la résistance au feu de l'élément pour une teneur en humidité f, en minutes;
f
T est la résistance au feu de l'élément à l'état anhydre, en minutes;
d
b est un facteur qui varie avec la perméabilité, en minutes.
Cette formule peut être utilisée, à quelques limites d'application près, pour corriger le critère d'isolation lié à un
élément de structure homogène tel que des dalles en béton, des murs en briques. Elle ne peut pas être utilisée
pour le bois et les produits en plâtre.
2.3  Augmentation de la taille
Si l'on augmente ses dimensions, un élément séparateur non porteur d'une classe donnée de résistance au feu
peut être utilisé pour une application demandant une classe de résistance inférieure à celle qui correspond à son

1)  T.Z. HARMATHY, Fire Safety Design and Concrete. Longman Scientific & Technical, 1993.
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classement. La raison en est que pour atteindre une meilleure performance que celle requise, il est nécessaire de
produire un élément plus stable pour réduire la distorsion ou la déformation et donc l'érosion des matériaux
constituants.
3  Éléments porteurs
En pratique, peu d'éléments de structure font l'objet d'une application directe car il existe toujours une différence de
taille ou de résistance entre les matériaux utilisés.
Pour les éléments porteurs protégés, voir aussi 5.2.
Pour les éléments simples, il est normal d'utiliser des codes de calculs qui prennent l'incendie en compte.
3.1  Poutres
3.1.1  Généralités
Les résultats d'un essai de résistance au feu peuvent être utilisés pour appuyer une évaluation des performances
d'une autre poutre sans avoir besoin de plus de calculs, de règles ou d'avis d'experts si la construction correspond
aux recommandations données en 3.1.2. Si la construction ne correspond pas à l'application directe, les calculs, les
règles d'application ou les avis d'experts doivent alors être appliqués comme indiqué.
Ce critère de performance pertinent est la résistance ultime (capacité portante déterminée par la déformation
maximale et la vitesse maximale de déformation).
3.1.2  Application directe
Les résultats d'un essai de résistance au feu sont considérés comme applicables à une poutre similaire non
essayée sous réserve que les éléments suivants soient tous vérifiés.
a) La portée n'est pas plus grande.
b) La charge n'est pas plus importante, son emplacement et sa répartition sont les mêmes.
c) Le niveau d'encastrement longitudinal et celui en rotation sont les mêmes.
d) Les dimensions de la section transversale ne sont pas inférieures.
e) La masse volumique et la résistance mécanique caractéristiques des matériaux de base sont les mêmes.
f) Le nombre de surfaces chauffées est le même.
g) La longueur de la partie non échauffée de la construction n'est pas diminué.
h) La conception de la section transversale (par exemple des armatures de renfort de la section transversale)
n'est pas modifié.
i) Il est possible de modifier ou d'ajouter des matériaux de revêtement ou de décoration qui n'ont pas d'effet sur la
résistance au feu.
3.1.3  Application étendue
3.1.3.1  Règles
Des règles peuvent être énoncées pour les éléments suivants.
a) Dimensions et chargement (portée, niveau et type de chargement)
La longueur et le chargement (niveau et répartition) peuvent être modifiées dans la mesure où le calcul montre
que cela n'augmente pas les contraintes (flexion et cisaillement) à l'intérieur de la section, et à condition que le
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mode de rupture à température ambiante ne varie pas (la portée peut être augmentée si le chargement est
réduit et vice versa).
(ne s'applique pas aux poutres en béton précontraint)
b) Armature des poutres en béton armé
Il est possible de modifier l'emplacement de l'armature tant que cela n'entraîne pas d'augmentation de sa
température, de réduction de la section transversale, ou de la distance entre l'armature et le centre de la zone
comprimée.
c) Nombre de surfaces échauffées
Le nombre de surfaces échauffées peut être réduit pour les poutres en matériaux pour lesquels cela ne nuira
pas à la performance.
d) Équipements
Des ouvertures pour équipements peuvent être incorporées si elles sont perpendiculaires à la portée, si elles
se trouvent dans la zone de l'axe neutre et si elles sont protégées sur leurs bords de la même manière que la
poutre elle-même.
e) Matériaux de revêtement
Il est possible de modifier ou d'ajouter des matériaux de revêtement ou de décoration qui n'ont pas d'effet sur la
résistance au feu.
3.1.3.2  Calculs de résistance au feu
Des calculs peuvent être utilisés pour les éléments suivants.
a) Champ de température
Il est possible de calculer la transmission de chaleur dans des poutres à l'aide de modèle accepté d'analyse de
température. Les données d'entrées doivent comprendre les valeurs de chaleur spécifique et de conductivité
thermique, fonctions de la température, pour tous les matériaux faisant partie de l'élément. Pour les éléments
composites, il est nécessaire d'estimer, en utilisant des résultats pertinents d'essais, la durée d'exposition à
partir de laquelle aura lieu la destruction ou le détachement de certaines parties de l'élément (c’est-à-dire des
panneaux, l'isolation, etc.).
b) Résistance ultime (capacité portante)
Il est possible de calculer la résistance ultime des poutres dont les propriétés physiques sont connues en
fonction de la température et dont le champ de température dans la section transversale est connu. Pour le
bois, il faut aussi connaître la vitesse de carbonisation et donc la réduction de la section transversale.
c) Flèche
Il est possible de calculer la flèche des poutres lorsqu'en plus des propriétés énumérées ci-dessus, les lois
contraintes-déformations (prenant en compte, si nécessaire, l'effet de fluage) en fonction de la température
sont connues. Il doit être noté que les flèches calculées doivent prendre en compte les déformations
thermiques et celles dues aux charges.
3.1.3.3  Avis d'experts
Il est possible de modifier les aspects suivants des poutres à condition que l'avis d'experts se fonde sur les
considérations appropriées mentionnées ci-dessous.
a) Conditions d'appui
Il est possible de modifier les conditions d'appui à condition que cela n'augmente pas l'effet de charge, ne
réduise pas le niveau d'encastrement en rotation, n'augmente pas le niveau d'encastrement longitudinal ni les
conditions thermiques.
b) Matériaux de protection
Lorsque les matériaux de protection au feu sont modifiés ou accrus afin de compenser des modifications du
chargement ou de la section transversale, il doit être prouvé (justifié) que la liaison entre le matériau de
protection et la poutre demeure efficace pendant suffisamment longtemps pour atteindre la durée requise de
résistance au feu.
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c) Surfaces chauffées
Il est possible d'augmenter le nombre des surfaces chauffées, s'il peut être démontré qu'en augmentant la
hauteur de la section transversale ou en diminuant le rapport entre le périmètre et la surface (par exemple), la
capacité portante est au moins équivalente à celle de la poutre essayée.
d) Composants
Il est possible de rajouter des composants à la construction de poutres (support rajouté pour les planchers ou
pour les autres poutres), à condition qu'il puisse être montré que cela ne réduit pas la résistance au feu.
e) Équipements
Des orifices perpendiculaires à la portée des poutres peuvent être autorisés sous réserve que les contraintes
(flexion et cisaillement) exercées à l'emplacement des ouvertures n'excèdent pas les contraintes maximales
correspondantes de la poutre essayée et que les ouvertures soient protégées sur leur bord afin d'éviter une
augmentation excessive de la température.
f) Protection des ouvertures
Lorsque des ouvertures sont pratiquées dans une poutre protégée, il est nécessaire de recouvrir leur bord afin
d'obtenir un niveau similaire de protection.
3.2  Poteaux
3.2.1  Généralités
Les résultats d'un essai de résistance au feu peuvent être utilisés pour appuyer une évaluation des performances
d'un autre poteau sans avoir besoin de plus de calculs, de règles ou d'avis d'experts si la construction correspond
aux recommandations données en 3.2.2. Si la construction ne correspond pas à l'application directe, les calculs, les
règles d'application ou les avis d'experts doivent alors être appliqués comme indiqués.
Le critère de performance pertinent est la résistance ultime ( capacité portante déterminée par la contraction axiale
maximale et la vitesse maximale de contraction axiale).
3.2.2  Application directe
Les résultats d'un essai de résistance au feu sont considérés comme applicables à un poteau similaire non essayé
sous réserve que les éléments suivants soient tous vérifiés.
a) La longueur n'est pas plus grande.
b) La charge n'est pas plus importante et son excentricité n'est pas augmentée.
c) Les conditions aux limites sont les mêmes.
d) Les dimensions de la section transversale ne sont pas diminuées.
e) La masse volumique et la résistance mécanique caractéristiques des matériaux de base sont les mêmes.
f) Le nombre de surfaces chauffées est le même.
g) La conception de la section transversale (par exemple des armatures de renfort de la section transversale)
n'est pas modifiée.
3.2.3  Application étendue
3.2.3.1  Règles
Des règles peuvent être données pour les éléments suivants.
a) Dimensions (y compris la longueur), chargement et conditions aux limites
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La longueur, l'élancement et la charge peuvent être modifiés tant qu'il est possible de montrer que le niveau de
chargement n'est pas plus élevé; par exemple la longueur peut être augmentée si la charge est réduite ou si
les conditions aux limites entraînent un élancement plus faible et vice versa.
b) Armature des poteaux en béton armé (ne s'applique pas aux poteaux en béton précontraint)
Il est possible de modifier l'emplacement de l'armature tant que sa température n'augmente pas, qu'il n'y a pas
d'effort de flexion et qu'il n'y a pas réduction de la section transversale.
c) Équipements
Les orifices d'un diamètre inférieur ou égal à X destinés aux équipements et percés dans des poteaux en
béton sont autorisés lorsque l'épaisseur du matériau de chaque côté de l'orifice mesure un minimum de X .
L'orifice ne doit couper aucune armature.
d) Matériaux de revêtement
Il est possible de modifier ou d'ajouter des matériaux de revêtement ou de décoration qui n'ont aucune
influence sur la résistance au feu.
3.2.3.2  Calculs de résistance au feu
Des calculs peuvent être utilisés pour les éléments suivants.
a) Champ de température
Il est possible de calculer la transmission de la chaleur dans des poteaux à l'aide de modèles acceptés
d'analyse de température. Les données d'entrées doivent comprendre les valeurs de chaleur spécifique et de
conductivité thermique, fonctions de la température, pour tous les matériaux faisant partie de l'élément. Pour
les éléments composites, il est nécessaire d'estimer, en utilisant des résultats pertinents d'essais, la durée
d'exposition à partir de laquelle aura lieu la destruction ou le détachement de certaines parties de l'élément
(c’est-à-dire des panneaux, l'isolation etc.).
b) Résistance ultime (capacité portante)
Il est possible de calculer la résistance ultime des colonnes dont les propriétés physiques sont connues en
fonction de la température et dont le champ de température dans la section transversale est connu. Pour le
bois, il faut aussi connaître la vitesse de carbonisation et donc la réduction de la section transversale.
c) Déplacement
Il est possible de calculer le déplacement (axial et latéral) des poteaux lorsqu'en plus des propriétés
énumérées ci-dessus, les lois contraintes-déformations (y compris, si nécessaire, l'effet de fluage) en fonction
de la température sont connues. Il doit être noté que les déplacements calculés doivent prendre en compte les
formations dues aux effets thermiques et aux charges.
d) Équipements
Des orifices pour équipements dans des poteaux en béton ou en matériau autre que du béton,
perpendiculaires à la longueur sont autorisés s'il est possible de calculer qu'à température élevée, ils ne
réduisent pas la résistance ultime.
3.2.3.3  Avis d'experts
Il est possible de modifier les aspects suivants des poteaux à condition que l'avis d'experts se fonde sur les
considérations appropriées mentionnées ci-dessous.
a) Conditions d'appui
Il est possible de modifier les conditions d'appui à condition que cela n'augmente pas l'effet de charge, ni ne
réduise les conditions de rotation ou thermique.
b) Matériaux de protection
Lorsque les matériaux de protection au feu sont modifiés ou accrus afin de compenser des modifications
effectuées dans les conditions de chargement ou dans la dimension de section transversale, il doit être prouvé
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(justifié) que la liaison entre le matériau de protection et le poteau demeure efficace pendant suffisamment
longtemps pour atteindre la durée requise de résistance au feu.
c) Composants
Il est possible d'ajouter des composants au poteau (appliques etc.) à condition qu'il puisse être montré que cela
ne réduit pas la résistance au feu.
d) Protection des orifices
Lorsque des orifices sont pratiqués dans un poteau protégé, il est nécessaire de recouvrir leur bord d'un niveau
similaire de protection.
3.3  Planchers
3.3.1  Généralités
Les résultats d'un essai de résistance au feu peuvent être utilisés pour appuyer une évaluation de la performance
d'un autre plancher sans avoir besoin de plus de calculs, de règles ou d'avis d'experts si la construction correspond
aux recommandations données en 3.3.2. Si la construction ne correspond pas à l'application directe, les calculs, les
règles d'application ou les avis d'experts doivent alors être appliqués comme indiqué.
Les critères de performance pertinents sont l'étanchéité (mesurée par un calibre d'ouverture, l'inflammation d'un
tampon de coton, ou une inflammation soutenue), l'isolation (augmentation de la température maximale ou
moyenne) et la résistance ultime (capacité portante: déterminée par la déformation maximale et la vitesse maximale
de déformation).
3.3.2  Application directe
Les résultats de l'essai de résistance au feu sont considérés comme applicables à un plancher similaire non essayé
sous réserve que les éléments suivants soient tous vérifiés.
a) La portée n'est pas plus grande et dans le cas d'un plancher reposant sur ses 4 côtés, le rapport entre les
portées reste le même.
b) La charge n'est pas plus importante, son emplacement et sa répartition restent les mêmes.
c) Le niveau d'encastrement longitudinal et celui en rotation restent les mêmes.
d) L'épaisseur n'est pas réduite.
e) La masse volumique et la résistance caractéristiques des matériaux de base sont les mêmes.
f) L'isolation thermique n'est réduite nulle part.
g) La longueur des éléments non échauffés de la structure n'est pas réduite.
h) Il n'y a pas de modification de la conception de la section transversale (par exemple l'emplacement des
armatures).
3.3.3  Application étendue
3.3.3.1  Règles
Des règles peuvent être énoncées pour les éléments suivants.
a) Dimensions
Le plancher peut être plus large, à condition qu'il y ait suffisamment d'espace aux extrémités pour permettre
une plus grande expansion thermique sans provoquer une rupture du système.
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b) Dimensions et chargement
La portée peut être accrue, à condition que la charge soit réduite et vice versa. Les modifications de la charge
ou de la portée ne doivent pas accroître les niveaux de contrainte à l'intérieur de la section en plus des
contraintes de calcul associées aux conditions de chargement de calcul en cas d'incendie.
Toute modification de la charge ou de la portée ne doit pas modifier le mode de rupture.
Si l'épaisseur du plancher est réduite suite à une réduction du chargement afin de maintenir les mêmes
niveaux de contrainte, le plancher doit toujours être d'une épaisseur suffisante pour pouvoir fournir une
isolation adéquate.
c) Modification de la masse volumique
Lorsqu'on remplace du béton normal par du béton léger, l'épaisseur de la dalle peut être réduite de X % en
fonction du critère d'isolation tant que la capacité portante est satisfaisante. La température des poutres en
acier et celle des planchers en acier en contact avec le béton augmentera lorsque du béton léger remplacera
du béton normal.
d) Matériaux de revêtement
Il est possible de modifier ou d'ajouter des matériaux de revêtement ou de décoration qui n'ont aucune
influence sur la résistance au feu.
3.3.3.2  Calculs de la résistance au feu
Des calculs peuvent être utilisés pour les éléments suivants.
a) Champ de température
Il est possible de calculer la transmission de chaleur dans des planchers à l'aide d'un modèle accepté
d'analyse de température. Les données d'entrée doivent comprendre des valeurs de chaleur spécifique et de
conductivité thermique fonctions de la température pour tous les matériaux faisant partie de l'élément. Pour les
éléments composites, il est nécessaire d'estimer, en utilisant des résultats pertinents d'essais, la durée
d'exposition à partir de laquelle aura lieu la destruction ou le détachement de certaines parties de l'élément
(c’est-à-dire des panneaux, l'isolation, etc.).
b) Performance d'isolation
Il est possible de calculer la conformité de l'élément au critère d'isolation à l'aide des champs de température
appropriés.
c) Résistance ultime
Il est possible de calculer la résistance ultime des planchers dont les propriétés physiques sont connues en
fonction de la température et quand le champ de température dans la section transversale du plancher est
connue. Pour le bois, la vitesse de carbonisation et donc la réduction de la section transversale doivent aussi
être connues.
d) Flèche
Il est possible de calculer la flèche des planchers lorsqu'en plus des propriétés énumérées ci-dessus, les lois
contraintes-déformations (y compris, si nécessaire, l'effet de fluage) fonctions de la température sont connues.
Il doit être noté que les flèches calculées doivent prendre en compte les déformations dues aux effets
thermiques et aux charges.
3.3.3.3  Avis d'experts
Il est possible de modifier les aspects suivants des planchers à condition que l'avis d'experts se fonde sur les
considérations appropriées mentionnées ci-dessous.
a) Conditions d'appui
Il est possible de modifier les conditions d'appui à condition que cela n'augmente pas l'effet de charge, ni ne
réduise les conditions de rotation ou thermiques.
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b) Équipements
Des équipements peuvent être créés dans le plancher, à condition que cela ne réduise pas la capacité de la
structure à satisfaire aux critères de résistance ultime, d'isolation et d’étanchéité.
c) Matériaux de protection
Lorsque les matériaux de protection au feu sont modifiés ou accrus afin de compenser les modifications
effectuées dans les conditions de chargement ou dans la dimension de la section transversale, il doit être
prouvé (justifié) que la liaison entre le matériau de protection et le plancher demeure efficace pendant
suffisamment longtemps pour atteindre la durée de résistance au feu.
d) Composants
Il est possible d'ajouter des composants au plancher à condition qu'il puisse être montré que cela ne réduit pas
la résistance au feu. Il doit être démontré que l'interaction des composants individuels n'affectera pas de
manière contraire la performance de la structure essayée.
e) Modification de la masse volumique
Il est possible de modifier la masse volumique des composants en bois sous réserve que la taille de la section
soit modifiée pour compenser la modification de la vitesse de carbonisation et toute autre modification associée
à la résistance.
Il est possible de modifier la masse volumique du béton, au-delà de ce qui a été autorisé dans la règle énoncée
en 3.3.3.1 c), à condition que soit prise en compte l'influence qu'aura cette modification sur la capacité
thermique et sur le flux de chaleur, en ce qui concerne à la fois le critère d'isolation thermique et la température
de tout élément support.
3.4  Murs
3.4.1  Généralités
Il existe deux sortes de murs: les murs de séparation qui doivent remplir des critères d'étanchéité, d'isolation et de
résistance ultime, et les murs qui n'ont pas de fonction séparatrice. Ce dernier type doit seulement remplir le critère
de performance relatif à la résistance ultime qui est le même que celui évoqué dans l'article traitant des poteaux.
Les résultats d'un essai de résistance au feu peuvent être utilisés pour appuyer une évaluation de la performance
d'un autre mur de séparation sans avoir besoin de plus de calculs, de règles ou d'avis d'experts si la construction
correspond aux recommandations données en 3.4.2. Si la construction ne correspond pas à l'application directe, les
calculs, les règles d'application ou les avis d'experts doivent alors être appliqués comme indiqué.
Les critères de performance pertinents sont l'étanchéité (mesurée par un calibre d'ouverture, l'inflammation d'un
tampon de coton, ou une inflammation soutenue), l'isolation (augmentation de la température maximale ou
moyenne) et la résistance ultime (capacité portante: déterminée par la déformation maximale et la vitesse maximale
de déformation).
3.4.2  Application directe
Les résultats d'un essai de résistance au feu sont considérés comme applicables à un plancher similaire non
essayé sous réserve que les éléments suivants soient tous vérifiés.
3.4.2.1  Partie solide d'un mur
a) La hauteur n'est pas plus grande.
b) La charge et son excentricité ne sont pas augmentées et l'emplacement de la charge reste le même.
c) Les conditions aux extrémités du mur restent les mêmes.
d) L'épaisseur n'est pas réduite.
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ISO
e) La masse volumique et la résistance mécanique caractéristiques des matériaux de base sont les mêmes.
f) L'isolation thermique n'est réduite nulle part.
g) Il n'y a pas de modification de la conception de la section transversale (par exemple l'emplacement des
armatures).
3.4.2.2  Ouvertures dans le mur
a) La taille d'une ouverture quelconque n'est pas acc
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