ISO TR 834-3-2012 Fire-resistance tests - Elements of building construction - Part 3 Commentary on test method and guide to the application of the outputs from .pdf

1、 ISO 2012 Fire-resistance tests Elements of building construction Part 3: Commentary on test method and guide to the application of the outputs from the fire-resistance test Essais de rsistance au feu lments de construction Partie 3: Commentaires sur les mthodes dessais et guides pour lapplication d

2、es rsultats des essais de rsistance au feu TECHNICAL REPORT ISO/TR 834-3 Second edition 2012-06-01 Reference number ISO/TR 834-3:2012(E) ISO/TR 834-3:2012(E) ii ISO 2012 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2012 All rights reserved. Unless otherwise specified, no part of this publica

3、tion may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva

4、20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ISO/TR 834-3:2012(E) ISO 2012 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope 1 2 Normative references . 1 3 Standard test procedure 1 3.1 Heating regimes . 2 3.2

5、 Furnace and equipment design . 3 3.3 Conditioning of the specimen 4 3.4 Fuel input and heat contribution . 5 3.5 Pressure measurement techniques . 5 3.6 Post heating procedures . 5 3.7 Specimen design . 6 3.8 Specimen construction 7 3.9 Specimen orientation . 8 3.10 Loading 8 3.11 Boundary conditio

6、ns and restraint and their influence on loadbearing capacity . 9 3.12 Performance verification . 11 4 Fire-resistance criteria .12 4.1 Objective 12 4.2 Load-bearing capacity .12 4.3 Integrity 12 4.4 Insulation .13 4.5 Radiation 13 4.6 Other characteristics 13 5 Classification 14 6 Repeatability and

7、reproducibility 14 6.1 Repeatability .15 6.2 Reproducibility .15 7 Establishing the field of application of test results .16 7.1 General .16 7.2 Interpolation 16 7.3 Extrapolation 17 8 Relationship between fire resistance and building fires 18 Annex A (informative) Uncertainty of measurement in fire

8、 resistance testing 20 Bibliography .25 ISO/TR 834-3:2012(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 commi

9、ttees. 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 I

10、nternational 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 Internationa

11、l 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

12、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 t

13、he 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 834-3 was prepared by Tech

14、nical Committee ISO/TC 92, Fire safety, Subc ommit tee SC 2, Fire containment. This second edition cancels and replaces the first edition (ISO/TR 834-3:1994), which has been technically revised. ISO/TR 834 consists of the following parts, under the general title Fire-resistance tests Elements of bui

15、lding construction: Part 1: General requirements Part 2: Guidance on measuring uniformity of furnace exposure on test samples Part 3: Commentary on test method and guide to the application of the outputs from the fire-resistance test Part 4: Specific requirements for loadbearing vertical separating

16、elements Part 5: Specific requirements for loadbearing horizontal separating elements Part 6: Specific requirements for beams Part 7: Specific requirements for columns Part 8: Specific requirements for non-loadbearing vertical separating elements Part 9: Specific requirements for non-loadbearing cei

17、ling elements The following parts are under preparation: Part 10: Specific requirements to determine the contribution of applied fire protection materials to structural elements Part 11: Specific requirements for the assessment of fire protection to structural steel elements Part 12: Specific requir

18、ements for separating elements evaluated on less than full scale furnaces iv ISO 2012 All rights reserved ISO/TR 834-3:2012(E) Introduction Fire resistance is a property of a construction and not of a material and the result achieved is to a large extent related to the design of the specimen and the

19、 quality of the construction. It is not an “absolute” property of the construction and variations in both the materials and methods of construction will produce differences in the measured performance and changes in the exposure conditions are likely to have an even greater impact on the level of fi

20、re resistance the element can provide. This part of ISO/TR 834 provides guidance to those contemplating testing, the laboratory staff performing the test, the designers of buildings, the specifiers and the authorities responsible for implementing fire safety legislation, to enable them to have a gre

21、ater understanding of the role of the fire resistance test and the correct application of its outputs. ISO 2012 All rights reserved v Fire-resistance tests Elements of building construction Part 3: Commentary on test method and guide to the application of the outputs from the fire-resistance test 1

22、Scope This part of ISO/TR 834 provides background and guidance on the use and limitations of the fire resistance test method and the application of the data obtained. It is designed to be of assistance to code officials, fire safety engineers, designers of buildings and other persons responsible for

23、 the safety of persons in and around buildings. This part of ISO/TR 834 identifies where the procedure can be improved by reference to ISO/TR 22898. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the editio

24、n cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 834-1:1999, Fire-resistance tests Elements of building construction Part 1: General requirements ISO/TR 834-2, Fire-resistance tests Elements of building construction Part 2

25、 Guide on measuring uniformity of furnace exposure on test samples ISO 3009, Fire-resistance tests Elements of building construction Glazed elements ISO/TR 12470, Fire-resistance tests Guidance on the application and extension of results ISO/TR 22898, Review of outputs for fire containment tests fo

26、r buildings in the context of fire safety engineering 3 Standard test procedure The primary purpose of a fire resistance test, e.g. ISO 834-1, is to characterize the thermal response of elements of construction when exposed to a fully developed fire within enclosures formed by, or within buildings.

27、The output of the test permits the construction tested by this method to be given a classification of performance within a time based classification system (see Clause 5). The test provides data that may be of use to a fire safety engineer, albeit the test only reproduces one, of many, potential fir

28、e scenarios. Practical considerations dictate that it is necessary to make a number of simplifications in any standard test procedure that is designed to replicate a real life event, in order to provide for its use under controlled conditions in any laboratory with the expectation of achieving repro

29、ducible and repeatable results. The fire resistance test is designed to apply to a particular fire scenario within the built environment, but with an understanding of its limitations and objectives it may be applied to other constructions. Some of the features which lead to a degree of variability a

30、re outside of the scope of the test procedure, particularly where material and constructional differences become critical. Other factors which have been identified in this part of ISO 834 are within the capacity of the user to accommodate. If appropriate attention is paid to these factors, the repro

31、ducibility and repeatability of the test procedure can be improved, possibly to an acceptable level. TECHNICAL REPORT ISO/TR 834-3:2012(E) ISO 2012 All rights reserved 1 ISO/TR 834-3:2012(E) 3.1 Heating regimes The standard furnace temperature curve described in ISO 834-1:1999, 6.1.1 is substantiall

32、y un changed from the time-temperature curve that has been employed to control the fire test exposure environment for the past 80 or so years. It was apparently related in some respects to temperatures experienced in some actual fires in buildings using referenced events, such as the observed time o

33、f fusion of materials of known melting points. The essential purpose of the standard temperature curve is to provide a standard test environment which is representative of one possible fully developed fire exposure condition, within which the performance of various representative forms of building c

34、onstruction may be compared. It is, however, important to recognize that this standard fire exposure condition does not necessarily represent an actual fire exposure situation. The test does, nevertheless, grade the performance of separating and structural elements of building construction on a comm

35、on basis. It should also be noted that the fire resistance rating accorded to a construction only relates to the test duration and not to the duration of a real fire. The relationship between the heating conditions, in terms of time-temperature prevailing in real fire conditions and those prevailing

36、 in the standard fire resistance test is discussed in Clause 8. A series of cooling curves is also discussed. Proposals have been made to simplify the equations to improve their ability to be computer processed. The comparison of the areas of the curves represented by the average recorded furnace te

37、mperature versus time and the above standard curve, in order to establish the deviation present, d e , as specified in ISO 834-1:1999, 6.1.2, may be achieved by using a planimeter over plotted values or by calculation employing either Simpsons rule or the trapezoidal rule. While the heating regime d

38、escribed in ISO 834-1:1999, 6.1.1, is the fire exposure condition which is the subject of this part of ISO/TR 834, it is recognized that it is not appropriate for the representation of the exposure conditions such as may be experienced from, for example, fires involving hydrocarbon fuels. While the

39、temperature conditions given in ISO 834-1:1999, 6.1.1 are seen to be the same as those used in previous editions of this standard, the method of measuring, and hence controlling the temperature within the furnace has changed significantly in the latest version of the standard. This change in the mea

40、suring instrument has come about as a result of a harmonising process between the European and International test procedures, as a result of implementing the Vienna Agreement. As part of the pan-European harmonisation process, the traditional use of bare wire thermocouples (or sheathed thermocouples

41、 with a similar time constant) for measuring the gas temperature within the furnace, has been abandoned in favour of the adoption of a “plate thermometer”. The theory behind the plate thermometer is that it receives the same thermal dose as the specimen, unaffected by the geometry of the furnace, th

42、e number and position of the burners and the nature of the fuel; all factors having been previously identified as causes of reproducibility and repeatability problems. This method of measuring temperature has been adopted in the latest version of ISO 834-1, and all of its parts. This device has a gr

43、eater time constant than the “bare wire” thermocouple described in the 1975 version of ISO 834, and as a consequence the gas temperature at any moment of time is likely to be higher than it was previously, particularly during the first 40 minutes. Therefore, while the latest version of ISO 834 follo

44、ws nominally the same temperature/time relationship the thermal dose will be measurably greater, particularly over the first 20 to 30 minutes, than when the previous bare wire thermocouples were used. Care should be taken when comparing the results of tests carried out in accordance with the earlier

45、 versions of ISO 834 and the present one ISO 834-1:1999, especially for constructions that are temperature sensitive. Thermocouples do “age” and the current that they generate as a result of the “couple” created between wires of dissimilar resistance at any temperature will differ with time. All tem

46、perature measuring devices, but in particular the plate thermometer, should be calibrated on a regular basis or discarded after a short time in use. 2 ISO 2012 All rights reserved ISO/TR 834-3:2012(E) 3.2 Furnace and equipment design 3.2.1 Factors affecting the thermal dose The heating conditions pr

47、escribed in ISO 834-1:1999, 6.1.1, are not sufficient by themselves to ensure that test furnaces of different design will each present the same fire exposure conditions to test specimens and hence provide for consistency in the test results obtained among these furnaces. The thermocouples employed f

48、or controlling the furnace temperature are in dynamic thermal equilibrium with an environment which is influenced by the radiative and convective heat transfer conditions existing in the furnace. The convective heat transfer to an exposed body depends upon its size and shape and is generally higher

49、with a small body than with a large body like a specimen. The convective component will therefore tend to have greater influence upon a bead thermocouple temperature while the heat transfer to a specimen is mainly affected by radiation from the hot furnace walls and the flames. For this reason the “plate” thermometer has replaced the bead thermocouple in ISO 834-1:1999, 5.5.1.1. The plate thermometer is more influenced by the total heat flux received by the specimen than the bead thermocouple. There i