ISO/TR 15655:2003

Fire resistance — Tests for thermo-physical and mechanical properties of structural materials at elevated temperatures for fire engineering design

ISO/TR 15655:2003 identifies test methods already in existence and provides guidance on those that need to be developed to characterize the thermo-physical and mechanical properties of structural materials at elevated temperatures for use in fire safety engineering calculations. It is applicable to materials used in load-bearing construction in which structural and thermal calculations might be required to assess the performance of elements or systems exposed to either standard fire tests, real or design fire heating conditions It is recognized that the elevated temperature properties of materials can be determined under a variety of conditions. Since fire is a relatively short transient process lasting from a few minutes to several hours, ideally, the properties determined should reflect the transient thermal and loading conditions as well as the duration of heating that may be experienced in practice. However, it is also recognized that some properties are relatively insensitive to the transient conditions and therefore, alternative steady state test methods may be appropriate. Some properties are sensitive to orientation effects, for example timber, and these should be considered with respect to how the tests are conducted. In cases where materials undergo either a chemical or a physical reaction during the heating process, it might be impossible to determine an individual property. ISO/TR 15655:2003 gives guidance in selecting a test method to determine an effective value representing a combination of properties. It is also recognized that a test specimen may comprise of a small construction such as that used in the testing of masonry. This often involves building a mini assembly to form a pyramid in order to represent the true behaviour. Apart from the traditional construction materials such as metals, concrete, masonry and wood, the use of plastics and fibre reinforcement is becoming more common. Therefore these materials have also been included in ISO/TR 15655:2003 to reflect possible future changes in design and advances in materials technology. In the past, the behaviour of jointing systems in fire has only received a little interest yet their behaviour is fundamental to the performance of composite elements and structural frames. ISO/TR 15655:2003 also addresses jointing systems under individual materials, for example welds for steel, glues for timber, they are considered in that section. However, in many cases the end use of an adhesive is not clear or it covers a range of applications. For this reason a separate category for adhesives is included. For some materials, it has not been possible to identify an existing standard or laboratory procedure for conducting tests at elevated temperatures under either steady state or, transient heating conditions. In these cases, standards for conducting tests at ambient temperature are identified. These may be considered to form the basis for development into a test method suitable at elevated temperatures.

Résistance au feu —Essais des propriétés thermophysiques et mécaniques des matériaux aux températures élevées pour la conception de l'ingénierie contre l'incendie

General Information

• Status: Withdrawn
• Publication Date: 27-Mar-2003
• Withdrawal Date: 27-Mar-2003
• ICS: 13.220.40 - Ignitability and burning behaviour of materials and products
• Technical Committee: ISO/TC 92/SC 2 - Fire containment
• Drafting Committee: ISO/TC 92/SC 2 - Fire containment
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 05-Mar-2020

Relations

• Revised: ISO/TR 15655:2020 - Fire resistance — Tests for thermo-physical and mechanical properties of structural materials at elevated temperatures for fire engineering design
• Effective Date: 02-Feb-2013

Standards Content (Sample)

TECHNICAL ISO/TR
REPORT 15655
First edition
2003-04-01

Fire resistance — Tests for
thermo-physical and mechanical
properties of structural materials at
elevated temperatures for fire
engineering design
Résistance au feu — Essais des propriétés thermophysiques et
mécaniques des matériaux aux températures élevées pour la
conception de l'ingénierie contre l'incendie




Reference number
ISO/TR 15655:2003(E)
©
ISO 2003

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ISO/TR 15655:2003(E)
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ii © ISO 2003 — All rights reserved

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ISO/TR 15655:2003(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Tests for thermal properties at elevated temperatures.3
2.1 Metals .3
2.2 Concrete .6
2.3 Masonry.10
2.4 Wood.13
2.5 Plastics, fibre reinforcement, organic and inorganic materials .16
2.6 Adhesives.19
3 Tests for mechanical properties at elevated temperatures .21
3.1 Metals .21
3.2 Concrete .27
3.3 Masonry.29
3.4 Wood.33
3.5 Plastics, fibre reinforcement, organic and inorganic materials .35
3.6 Adhesives.38
Bibliography.41

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ISO/TR 15655:2003(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In exceptional circumstances, 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), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides are considered to be no
longer valid or useful.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TR 15655 was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 2, Fire
containment.
ISO/TR 15655 is one of a series of documents developed by ISO/TC 92 that provide guidance on important
aspects of calculation methods for fire resistance of structures. The others in this series are currently in
preparation and include:
 ISO/TS 15656, Fire resistance — Guide for evaluating the capability of calculation models for structural
fire behaviour
 ISO/TS 15657, Fire resistance — Guidelines on computational structural fire design
 ISO/TS 15658, Fire resistance — Guidelines for full scale structural fire tests
Other related documents developed by ISO/TC 92/SC 2 that also provide data and information for the
determination of fire resistance include:
 ISO 834 (all parts), Fire-resistance tests — Elements of building construction
 ISO/TR 10158, Principles and rationale underlying calculation methods in relation to fire resistance of
structural elements
 ISO/TR 12470, Fire-resistance tests — Guidance on the application and extension of results
1)
 ISO/TR 12471 , Computational structural fire design — State of the art and the need for further
development of calculation models and for fire tests for determination of input material data required

1) In preparation.
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ISO/TR 15655:2003(E)
Introduction
Fire engineering has developed to the stage whereby detailed calculation procedures are now being carried
out to establish the behaviour of structural elements and frames under the action of fire. These cover standard
[1]
fire resistance furnace tests such as ISO 834 as well as natural/real fires, in which performance based
criteria covering stability, integrity and insulation may need to be determined.
As fire engineering is advanced through the development of design codes and standards, there is an
increasing need to provide as inputs to the numerical calculations, the thermal and mechanical properties of
construction materials at elevated temperatures. In addition, as part of the process in applying rules for the
interpolation and extension of fire resistance test results, specific data on material properties is often required
to conduct assessments on variations in construction other than those tested.
It is important therefore, that information on the behaviour of structural materials at elevated temperatures is
available to the fire engineer and confidence is provided in its use as a result of being determined using
established and accepted laboratory techniques and test standards. Since it is also possible to determine the
properties of materials under a variety of experimental conditions, those adopted should reflect the heating
and loading conditions that may be experienced in either real fires or standard fire resistance tests.
The objectives of this Technical Report relate to test methods for determining the thermal and mechanical
properties of construction materials for use in fire engineering design and has therefore been prepared to:
 Identify the existence of national or International Standards that provide suitable test methods for
determining the thermal and mechanical properties at elevated temperatures of materials used in load
bearing construction.
 Identify whether the test methods are based upon steady state or transient heating conditions and provide
information on the limits of experimental conditions. For steady state tests, comment where possible, on
the sensitivity of the parameter to the heating conditions and/or the suitability of the method being
adopted for transient tests.
 Identify through the scientific literature, experimental techniques that have been used to determine a
material property, which may be adopted by a standards body as a basis for further development into a
full test standard. However, it should be noted that it is not the intention of this Technical Report to
provide a definitive list of references but sources of information are given as an aid to initially reviewing
some of the work conducted in a particular field of research.
 Comment on the limitations of developing a test method for a particular thermal or mechanical property in
which it may be more appropriate to measure a combination of properties.
 Identify/prioritize the need for test methods that will have an immediate benefit in providing data for fire
engineering calculations.
Currently, there is an active technical group of leading experts working in the field of developing test methods
for concrete members. This work is being conducted within International Union of Testing and Research
Laboratories for Materials and Structures, RILEM TC 129-MHT, under the convenorship of Professor
Schneider. In this Technical Report, reference is made to test methods being currently developed which are
applicable to concrete structures exposed to fire. In some cases, the test methods being developed could be
applied to the testing of masonry products.
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TECHNICAL REPORT ISO/TR 15655:2003(E)

Fire resistance — Tests for thermo-physical and mechanical
properties of structural materials at elevated temperatures for
fire engineering design
1 Scope
This Technical Report identifies test methods already in existence and provides guidance on those that need
to be developed to characterize the thermo-physical and mechanical properties of structural materials at
elevated temperatures for use in fire safety engineering calculations.
It is applicable to materials used in load-bearing construction in which structural and thermal calculations
might be required to assess the performance of elements or systems exposed to either standard fire tests,
real or design fire heating conditions.
It is recognized that the elevated temperature properties of materials can be determined under a variety of
conditions. Since fire is a relatively short transient process lasting from a few minutes to several hours, ideally,
the properties determined should reflect the transient thermal and loading conditions as well as the duration of
heating that may be experienced in practice. However, it is also recognized that some properties are relatively
insensitive to the transient conditions and therefore, alternative steady state test methods may be appropriate.
Some properties are sensitive to orientation effects, for example timber, and these should be considered with
respect to how the tests are conducted.
In cases where materials undergo either a chemical or a physical reaction during the heating process, it might
be impossible to determine an individual property. This Technical Report gives guidance in selecting a test
method to determine an effective value representing a combination of properties. It is also recognized that a
test specimen may be comprised of a small construction such as that used in the testing of masonry. This
often involves building a mini assembly to form a pyramid in order to represent the true behaviour.
Apart from the traditional construction materials such as metals, concrete, masonry and wood, the use of
plastics and fibre reinforcement is becoming more common. Therefore these materials have also been
included in this Technical Report to reflect possible future changes in design and advances in materials
technology.
In the past, the behaviour of jointing systems in fire has only received a little interest yet their behaviour is
fundamental to the performance of composite elements and structural frames. This Technical Report also
addresses jointing systems under individual materials, for example welds for steel, glues for timber. However,
in many cases, the end use of an adhesive is not clear or it covers a range of applications. For this reason a
separate category for adhesives is included.
For some materials, it has not been possible to identify an existing standard or laboratory procedure for
conducting tests at elevated temperatures under either steady state or transient heating conditions. In these
cases, standards for conducting tests at ambient temperature are identified. These may be considered to form
the basis for development into a test method suitable at elevated temperatures.
Based upon current fire design methodologies and those that are beginning to receive attention, Table 1 and
Table 2 summarize the requirements and availability of test methods for measuring the thermal and
mechanical properties considered to have an immediate priority.
NOTE For composite concrete and steel structures the material properties required are addressed under each
individual material.
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ISO/TR 15655:2003(E)
Table 1 —Summary of test methods available for measuring the thermo-physical properties at
elevated temperatures
Material
Plastics, fibre
Thermal property
reinforcement,
Metals Concrete Masonry Wood Adhesives
organic and
inorganic
a a a a b b a b a b
Specific heat L L , S S , L L S , L S , L
b b b b b a b b b b
Thermal conductivity L L , S L , S L , S L , S L
a a b a b a a b a
Thermal diffusivity L L , S L , S L L , S L
a a b a b a a
Linear expansion L L , S L , S — S S
a a b a b a a
Linear contraction L L , S L , S — S S
a a a a a a
Density — S S L S L , S
a a
Charring rate — — — L , S — —
a a a a a a a a
Emissivity L L , S L , S S S S
a b a a
Spalling — L , S L , S — — —
a a
Shrinkage — S S — — —
a a a
Moisture — S S L — —
Others — — — — — —
L Laboratory test method
S Standard test method
— Property not required
a
Laboratory or standard test method available suitable for fire engineering but may still require further development.
b
Laboratory or standard test method may be suitable for elevated temperature testing but requires further development into a
transient test to be suitable for fire engineering.

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ISO/TR 15655:2003(E)
Table 2 —Summary of test methods available for measuring the mechanical properties at elevated
temperatures
Material
Plastics, fibre
Mechanical property
reinforcement,
Metals Concrete Masonry Wood Adhesives
organic and
inorganic
a a a a a
Elastic modulus L L , S L L X X
Shear modulus — — X — X —
b
Modulus of rupture — — S — — —
a a
Poissons ratio — L — L X —
a a a b a
Creep S L L , S L X X
a a a
Stress relaxation L , S L — — — —
Bauschinger effect X — — — — —
a a a
Stress/strain Steady state S L L — X —
a a a
Transient state L L L — X —
a a b
Ultimate strength Compression X L L L X X
b
Shear — — X L X X
a a a b
Tension L , S L — L X X
b b
Shear — — — L — S
b b
Adhesive strength Tension — — — L — S
Delamination — — — X — —
b
Bending/flexure strength — — X X — S
a
Joints (in general) L — X X X —
Others — — — — — —
L Laboratory test method
S Standard test method
X No elevated temperature test method available
— Property not required
a
Laboratory or standard test method available suitable for fire engineering but may still require further development.
b
Laboratory or standard test method may be suitable for elevated temperature testing but requires further development into a
transient test to be suitable for fire engineering.
2 Tests for thermal properties at elevated temperatures
2.1 Metals
2.1.1 General
In this section metals that may be used as structural components include aluminium alloys, mild and micro-
alloyed steels and stainless steels. Under fire conditions, the heating rates of interest will generally fall within
the range 1 °C/min to 50 °C/min. The extremes represent situations from heavily protected steelwork such as
reinforcement encased within several inches of concrete cover to fully exposed members.
It is recommended that test methods for thermal properties should be capable of evaluating steels at
temperatures up to 1 200 °C, and aluminium up to 600 °C.
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ISO/TR 15655:2003(E)
2.1.2 Specific heat
2.1.2.1 National or International Standards
[3]
There is no standard identified specifically for metals although reference should be made to ISO 11357-1 for
using the differential scanning calorimeter.
2.1.2.2 Laboratory test methods or procedures under development
Laboratory test methods or procedures under development are being carried out by the following:
 The differential scanning calorimeter has been used under transient heating conditions for heating rates
up to 10 °C/min for aluminium and steel. However, for steel it is not particularly suitable for temperatures
greater than the transformation temperature (approximately 720 °C).
 The potential drop calorimeter/spot methods have been carried out on steel at temperatures up to
[4] [5]
1 300 °C. Pallister has reported a test procedure in which specimens are heated at rates of up to
10 °C/min, momentarily stabilized and then subjected to a controlled electrical pulse. The resulting
change in temperature is accurately measured. The test method is also used to measure specific heat
during cooling. Although the test method was developed for steel, the technique can in principle, be
applied to aluminium.
[6]
 A similar electrical adiabatic technique is reported by Awberry in which measurements on steel samples
are taken continuously as they are heated at a rate of 3 °C/min.
A more detailed review of the specific heat data for steels and the measuring techniques are presented in a
[7]
paper by Preston .
Although no test standard has been identified, techniques for measuring the specific heat of metals have been
established for several years and could readily form the basis of a standard.
2.1.3 Thermal conductivity
2.1.3.1 National or International Standards
[8] [9]
See ISO 8301 and ISO 8302 .
2.1.3.2 Laboratory test methods or procedures under development
Laboratory test methods or procedures under development are being carried out by the following:
[10]
 Powell describes a method for measuring thermal conductivity under transient heating conditions for
steel using a heating rate of 3 °C/min to 4 °C/min. The technique involves measuring the electrical
resistivity at elevated temperatures during continuous heating up to 1 300 °C.
 Measurements of thermal conductivity during continuous (transient) longitudinal and radial heat flow have
been described in Reference [11] of the Bibliography. Tests have been conducted on steel for
temperatures up to 1 000 °C. As before, the methods rely on measuring changes in electrical resistance
for establishing thermal conductivity.
2.1.4 Thermal diffusivity
2.1.4.1 National or International Standards
No standards have been identified.
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ISO/TR 15655:2003(E)
2.1.4.2 Laboratory test methods or procedures under development
A new method for measuring thermal conductivity and diffusivity that is similar in principle to the hot wire, has
[12]
been developed by Gustaffsson . This is referred to as the transient plane source (TPS) technique.
[13]
The experimental procedure has been described in papers by Grauers and Persson and Log and
[14]
Gustaffsson . A thin layer of electrically conducting material (nickel) which acts as both a heat source and a
temperature-measuring device is sandwiched between two samples of the material. The assembly is heated
in a conventional furnace to the desired temperature and stabilized to avoid any thermal gradients before the
electrical pulse is triggered. The temperature rise of the metal strip, which is measured by its change in
resistivity, depends upon the rate heat is conducted into the material.
Success has been reported in applying the technique for measuring the thermal conductivity and diffusivity for
several materials including stainless steel and aluminium. However, no information has been found to
demonstrate that it has been used in metals and alloys at elevated temperatures. For other materials, it has
been used successfully at temperatures up to 1 000 K. Currently the test method has only been developed for
steady state heating conditions. Although the authors state that the technique could be combined with the
constant rate of temperature rise (CRTR) method for measuring diffusivity, which is carried out under transient
heating conditions, this is questionable. However, the advantage of the technique is that from a single test,
values for the combined effect of more than one parameter are obtained.
2.1.5 Thermal strain (expansion and contraction)
2.1.5.1 National or International Standards
No standards have been identified.
2.1.5.2 Laboratory test methods or procedures under development
Laboratory test methods or procedures under development are being carried out by the following:
 British Steel Swinden Technology, UK;
 National Physical Laboratory, UK;
 Welding Institute, UK.
Although no test standards could be identified, commercial equipment exist that rely on being able to
accurately measure both expansion and contraction as part of studying metallurgical transformation processes
in metals and alloys. These are generally referred to as “dilatometer” tests in which heating rates in excess of
100 °C/s can be accurately controlled from ambient temperature up to the melting point. Specimens are
generally heated by electrical induction or resistance heating often through the specimen itself, and are
capable of replicating heating cycles used in fire resistance tests and natural fires. For carbon steel there is a
heating rate dependence through the magnetic transformation temperature (approximately 740 °C).
The laboratory procedures could be readily developed into a standard.
2.1.6 Emissivity
2.1.6.1 National or International Standards
[15]
No standard identified specifically for metals but reference should be made to ISO 8990 for calibrated and
guarded hot box.
2.1.6.2 Laboratory test methods or procedures under development
“Black box” calibration methods are widely used in many laboratories.
It is recommended to use steady state methods for measuring emissivity.
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ISO/TR 15655:2003(E)
2.2 Concrete
2.2.1 General
During heating, concrete undergoes both chemical and physical changes such as loss of moisture,
dehydration, de-carbonization, quartz conversion, etc. These effects can have a significant influence on the
thermal and mechanical performance of structural elements at elevated temperatures. For the majority of test
methods carried out to determine the thermal and mechanical properties, it is preferable that these are
conducted under transient heating conditions.
Since concrete is a poor conductor of heat, in order to reflect the majority of fire conditions, it is recommended
that tests be carried out at heating rates within the range of 0,5 °C/min to 10 °C/min with an upper limit of
1 000 °C.
2.2.2 Specific heat
2.2.2.1 National or International standard
[3]
The differential scanning calorimeter (DSC), ISO 11357-1 , has been successfully applied to evaluating
concrete under transient heating conditions but is limited in its application to temperatures up to around
500 °C.
2.2.2.2 Laboratory test methods or procedures under development
Laboratory test methods or procedures under development are being carried out by the following:
 Japan Testing Centre for Construction Materials, T = 20 °C to 150 °C;
 General Building Research Corporation of Japan, T = 20 °C to 90 °C;
 Swedish National Testing Research Institute, transient test method is used.
2.2.3 Thermal conductivity
2.2.3.1 National or International Standards
The following national standards have been found which could be adopted or are already in place for testing
concrete. Each method is based upon steady state heating conditions:
[16]
a) BS 1902-5.5 ;
[17]
b) BS 1902-5.6 ;
[18]
c) BS 1902-5.8 ;
[19]
d) JIS A1412 used at:
1) Japan Testing Centre for Construction Materials (small scale tests);
2) General Building Research Corporation of Japan (small scale tests);
[8]
e) ISO 8301 ;
[9]
f) ISO 8302 ;
[20]
g) JIS R2618 .
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ISO/TR 15655:2003(E)
2.2.3.2 Laboratory test methods or procedures under development
A new method for measuring thermal conductivity and diffusivity that is similar in principle to the hot wire, has
[12]
been developed by Gustaffsson . This is referred to as the transient plane source (TPS) technique.
[13]
The experimental procedure has been described in papers by Grauers and Persson and Log and
[14]
Gustaffsson . A thin layer of electrically conducting material (nickel) which acts as both a heat source and a
temperature-measuring device, is sandwiched between two samples of the material. The assembly is heated
in a conventional furnace to the desired temperature and stabilized to avoid any thermal gradients before the
electrical pulse is triggered. The temperature rise of the metal strip, which is measured by its change in
resistivity, depends upon the rate heat is conducted into the material.
Success has been reported in applying the technique for measuring the thermal conductivity and diffusivity for
several materials including concrete at temperatures up to 1 000 K. Currently the test method has only been
developed for steady state heating conditions. However, the authors state that the technique could be
combined with the constant rate of temperature rise (CRTR) method for measuring diffusivity, which is carried
out under transient heating conditions. Furthermore, this technique is questionable and warrants further
investigation.
2.2.4 Thermal diffusivity
2.2.4.1 National or International Standards
The following standards have been identified for steady state heating conditions:
[21]
a) JIS A1325 is used at:
1) Japan Testing Centre for Construction Materials;
2) General Building Research Corporation of Japan, T = 20 °C to 90 °C.
[22]
b) ENV 1159-2 . This standard was originally developed for evaluating ceramic matrix composites with
continuous reinforcement. It involves a laser flash experimental procedure that is carried out under steady
state heating conditions at temperatures up to 2 800 K.
2.2.4.2 Laboratory test methods or procedures under development
The transient plane source test method described in 2.2.2.2 can also be used to determine thermal diffusivity.
However, the technique needs to be further developed in conjunction with the constant rate temperature rise
method for transient heating conditions.
Measuring the diffusivity of concrete using the transient plane source technique avoids the necessity of
requiring the specific heat to be determined for calculating heat transfer characteristics. In this respect, more
acc
...