EN 13381.pdf
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2003-01-27
ICS:13.220.50
ΕΛΟΤ ENV 13381.04
ΕΛΛΗΝΙΚΟ ΠΡΟΤΥΠΟ HELLENIC STANDARD
Μέθοδοι δοκιµής για τον προσδιορισµό της συµβολής στην πυραντίσταση δοµικών στοιχείων - Μέρος 4: Εφαρµοσµένη προστασία σε χαλύβδινα στοιχεία Test methods for determining the contribution to the fire resistance of structural members - Part 4: Applied protection to steel members
Κλάση Τιµολόγησης: 21 ΕΛΛΗΝΙΚΟΣ ΟΡΓΑΝΙΣΜΟΣ ΤΥΠΟΠΟΙΗΣHΣ Α.Ε.
© ΕΛΟΤ
Αχαρνών 313 •11145 Αθήνα
ΕΛΟΤ ENV 13381.04
Εθνικός Πρόλογος
National Foreword
Αυτό είναι το Φύλλο Επικύρωσης του εγκεκριµένου Ευρωπαϊκού Προτύπου
This Endorsement Sheet ratifies the approval of European Standard
ENV 13381-4 : 2002
ENV 13381-4 : 2002
ως Ελληνικού Προτύπου. Το πρότυπο αυτό διατίθεται στην Αγγλική, ή Γαλλική ή Γερµανική γλώσσα από τον Ελληνικό Oργανισµό Τυποποίησης Α.Ε.
as a Hellenic Standard. This standard is available in English, French or German from the Hellenic Organization for Standardization S.A.
EUROPEAN PRESTANDARD
ENV 13381-4
PRÉNORME EUROPÉENNE EUROPÄISCHE VORNORM
July 2002
ICS 13.220.50
English version
Test methods for determining the contribution to the fire resistance of structural members - Part 4: Applied protection to steel members
This European Prestandard (ENV) was approved by CEN on 1 March 2002 as a prospective standard for provisional application. The period of validity of this ENV is limited initially to three years. After two years the members of CEN will be requested to submit their comments, particularly on the question whether the ENV can be converted into a European Standard. CEN members are required to announce the existence of this ENV in the same way as for an EN and to make the ENV available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the ENV) until the final decision about the possible conversion of the ENV into an EN is reached. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36
© 2002 CEN
All rights of exploitation in any form and by any means reserved worldwide for CEN national Members.
B-1050 Brussels
Ref. No. ENV 13381-4:2002 E
ENV 13381-4:2002 (E)
Contents page
Foreword ...............................................................................................................................................................3 1 Scope ............................................................................................................................................................4 2 Normative references ....................................................................................................................................5 3 Terms and definitions, symbols and units.....................................................................................................5 4 Test equipment .............................................................................................................................................8 5 Test conditions..............................................................................................................................................8 6 Test specimens............................................................................................................................................10 7 Installation of the test specimens ................................................................................................................15 8 Conditioning of the test specimens .............................................................................................................16 9 Application of instrumentation ...................................................................................................................16 10 Test procedure ............................................................................................................................................18 11 Test results..................................................................................................................................................20 12 Test report...................................................................................................................................................21 13 Assessment .................................................................................................................................................22 14 Report of the assessment.............................................................................................................................29 15 Limits of the applicability of the results of the assessment .........................................................................30 Annex A (normative) Test method to the smouldering fire or slow heating curve .............................................53 Annex B (normative) The applicability of the results of the assessment to sections other than ‘I’ or ‘H’ section .................................................................................................................................................................56 Annex C (normative) Measurement of properties of fire protection materials ...................................................58 Annex D (normative) Fixing of thermocouples to steel work and routing of cables ..........................................61 Annex E (normative) Correction for discrepancies in thickness between loaded and equivalent unloaded sections ................................................................................................................................................................63 Annex F (normative) Assessment methodology: Differential equation analysis (variable approach) ..............64 Annex G (normative) Assessment methodology: Differential equation analysis (constant approach).............70 Annex H (normative) Assessment methodology: Numerical regression analysis ...............................................72 Annex J (normative) Assessment methodology: Graphical presentation............................................................74 Bibliography........................................................................................................................................................76
2
ENV 13381-4:2002 (E)
Foreword This document ENV 13381-4:2002 has been prepared by Technical Committee CEN/TC127 "Fire safety in buildings", the secretariat of which is held by BSI. This document has been prepared under the mandate given to CEN/TC127 by the Commission and the European Free Trade Association. As there was little experience in carrying out these tests in Europe CEN/TC127 agreed that more experience should be built up during a prestandardization period before agreeing text as European Standards. Consequently all parts are being prepared as European Prestandards. This European Prestandard is one of a series of standards for evaluating the contribution to the fire resistance of structural members by applied fire protection materials. Other parts of this ENV are: Part 1: Horizontal protective membranes. Part 2: Vertical protective membranes. Part 3: Applied protection to concrete members. Part 5: Applied protection to concrete/profiled sheet steel composite members. Part 6: Applied protection to concrete filled hollow steel composite columns. Part 7: Applied protection to timber members. Annexes A to J are normative. Caution The attention of all persons concerned with managing and carrying out this fire resistance test, is drawn to the fact that fire testing can be hazardous and that there is a possibility that toxic and / or harmful smoke and gases can be evolved during the test. Mechanical and operational hazards can also arise during the construction of test elements or structures, their testing and the disposal of test residues. An assessment of all potential hazards and risks to health should be made and safety precautions should be identified and provided. Written safety instructions should be issued. Appropriate training should be given to relevant personnel. Laboratory personnel should ensure that they follow written safety instructions at all times. The specific health and safety instructions contained within this prestandard should be followed. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to announce this European Prestandard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.
3
ENV 13381-4:2002 (E)
1
Scope This part of this European Prestandard specifies a test method for determining the contribution made by applied fire protection systems to the fire resistance of structural steel members, which can be used as beams, columns or tension members. The evaluation is designed to cover a range of thicknesses of the applied fire protection material, a range of steel sections, characterized by their section factors, a range of design temperatures and a range of valid fire protection classification periods. This European Prestandard applies to fire protection materials where the gap between the material and the flange faces of the steel member is less than 5 mm in size. Otherwise, the test methods in ENV 13381-1 or ENV 13381-2, as appropriate, apply. This European Prestandard contains the fire test which specifies the tests which should be carried out to determine the ability of the fire protection system to remain coherent and fixed to the steelwork, and to provide data on the thermal characteristics of the fire protection system, when exposed to the standard temperature/time curve specified in EN 1363-1. In special circumstances, where specified in national building regulations, there can be a need to subject reactive protection material to a smouldering curve. The test for this and the special circumstances for its use are described in annex A. The fire test methodology makes provision for the collection and presentation of data which can be used as direct input to the calculation of fire resistance of steel structural members in accordance with the procedures given in ENV 1993-1-2. This European Prestandard also contains the assessment which prescribes how the analysis of the test data should be made and gives guidance on the procedures by which interpolation should be undertaken. The assessment procedure is used to establish: a)
on the basis of temperature data derived from testing loaded and unloaded sections, a correction factor and any practical constraints on the use of the fire protection system under fire test conditions, (the physical performance);
b)
on the basis of the temperature data derived from testing short steel column sections, the thermal properties of the fire protection system, (the thermal performance).
The limits of applicability of the results of the assessment arising from the fire test are defined, together with permitted direct application of the results to different steel sections and grades and to different fire protection systems and fixings. The results of the test and assessment obtained according to this part of ENV 13381 are directly applicable to steel sections of "I" and "H" cross sectional shape. Guidance is given in annex B on the application of the data obtained from "I" and "H" steel sections to other section shapes.
4
ENV 13381-4:2002 (E)
2
Normative references This European Prestandard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text, and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Prestandard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). EN 1363-1
Fire resistance tests - Part 1: General requirements.
EN 1363-2
Fire resistance tests - Part 2: Alternative and additional procedures.
EN 10025
Hot rolled products of non-alloy structural steels - Technical delivery conditions.
EN 10113
Hot rolled products in weldable fine grade structural steels.
ENV 1993-1-1
Eurocode 3: Design of steel structures Part 1-1: General rules and rules for buildings.
ENV 1993-1-2
Eurocode 3: Design of steel structures Part 1-2: General rules - Structural fire design.
ISO 8421-2
Fire protection - Vocabulary - Part 2: Structural fire protection.
EN ISO 13943
Fire safety - Vocabulary (ISO 13943:1999).
3
Terms and definitions, symbols and units
3.1
Terms and definitions
For the purposes of this European Prestandard, the terms and definitions given in EN 1363-1, EN ISO 13943 and ISO 8421-2, together with the following, apply: 3.1.1 steel member element of building construction which is loadbearing and fabricated from steel 3.1.2 fire protection material material or combination of materials applied to the surface of a steel member for the purpose of increasing its fire resistance 3.1.3 passive fire protection materials materials which do not change their physical form on heating, providing fire protection by virtue of their physical or thermal properties. They may include materials containing water which, on heating,, evaporates to produce cooling effects 3.1.4 reactive fire protection materials materials which are specifically formulated to provide a chemical reaction upon heating such that their physical form changes and in so doing provide fire protection by thermal insulative and cooling effects 3.1.5 fire protection system fire protection material together with a prescribed method of attachment to the steel member
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ENV 13381-4:2002 (E)
3.1.6 fire protection protection afforded to the steel member by the fire protection system such that the temperature of the steel member is limited throughout the period of exposure to fire 3.1.7 test specimen steel test section plus the fire protection system under test. The steel test section, representative of a steel member, for the purposes of this test, comprises short steel columns, tall columns or beams 3.1.8 fire protection thickness thickness of a single layer fire protection system or the combined thickness of all layers of a multilayer fire protection system 3.1.9 stickability ability of a fire protection material to remain sufficiently coherent and in position for a well defined range of deformations, furnace and steel temperatures, such that its ability to provide fire protection is not significantly impaired 3.1.10 section factor profiled ratio of the fire exposed outer perimeter area of the steel structural member itself, per unit length, to its cross sectional volume per unit length, see Figure 1 boxed ratio of the sum of the inside dimensions of the smallest possible rectangle or square encasement which can be measured round the steel structural member times unit length, to its volume per unit length, see Figure 1 3.1.11 design temperature temperature of a steel structural member for structural design purposes 3.1.12 characteristic steel temperature temperature of the steel structural member which is used for the determination of the correction factor for stickability
3.2
Symbols and units Symbol
Unit
LB UB LC TC SC p a f d Am/V Ap/V Ap 6
Description loaded beam section unloaded beam section loaded 3 metre column section unloaded Tall (2 metre) column section short column section fire protection material steel furnace thickness density
m-1 m-1 m2/m
section factor of the unprotected steel section section factor of the protected steel section area of the protected steel section, around the profile (profiled) or over the linear
ENV 13381-4:2002 (E)
A V Vp h b tw
m2 m3/m m3/m mm mm mm
dimensions (boxed) of the steel section cross sectional area of the steel section volume of the steel section per unit length volume of the fire protection material per unit length depth of the steel section flange breadth of the steel section thickness of the web of the steel section
Lexp Lsup
mm mm
length of beam specimen exposed to heating length of beam specimen between supports
dUB dSC dp dp(max) dp(min)
mm mm mm mm mm
thickness of fire protection material on an unloaded beam section thickness of fire protection material on an unloaded column section thickness of fire protection material concerned maximum thickness of fire protection material used minimum thickness of fire protection material used
protection UB SC LB a SC LB UB LC TC c(UB) t at
kg/m3 kg/m3 kg/m3 kg/m3 kg/m3 °C °C °C °C °C °C °C °C
density of fire protection material density of fire protection material on an unloaded beam section density of fire protection material on an unloaded column section density of fire protection material on a loaded beam density of steel (normally 7850 kg/m3) mean (or characteristic) steel temperature of a short column (see 13.2.2) characteristic steel temperature of a loaded beam characteristic steel temperature of an unloaded beam characteristic steel temperature of a loaded column characteristic steel temperature of a tall column corrected temperature of an unloaded beam section average temperature of the furnace at time t average temperature of the steel at time t
t
°C
increase of furnace temperature during the time interval
m(SC)
°C
modified steel temperature of an unloaded column section
D
°C
design temperature
k()
correction factor for temperature of an unloaded section at a temperature
k(LB)max
correction factor for temperature based on beams for a short section at a temperature with maximum thickness of applied fire protection material
k(LB)min
correction factor for temperature based on beams for a short section at a temperature with minimum thickness of applied fire protection material
k()C
correction factor for temperature based on columns for a short section at a temperature with maximum thickness of applied fire protection material
kd()
correction factor for temperature of a short column section at a thickness of fire protection material d and at a temperature
kd(LB)
correction factor for temperature based on beams for a short section at a thickness of fire protection material d and at a temperature
kd(TC)
correction factor for temperature based on tall columns (or loaded columns) for a short section at a thickness of fire protection material d and at a temperature
kmax()
correction factor for temperature of a short section at maximum thickness of fire protection material dmax 7
ENV 13381-4:2002 (E)
kmin()
Ca Cp
correction factor for temperature of a short section at minimum thickness of fire protection material dmin J/kg °C J/kg °C
temperature dependant specific heat of steel as defined in ENV 1993-1-2 temperature independant specific heat of the fire protection material ratio of heat capacity of the fire protection material to that of the steel section
t te
min min
t tD p char(p) ave(p)
min min W/m °C W/m °C W/m °C
time from commencement of the start of the test time for an unloaded section to reach an equivalent temperature to the loaded beam at time t time interval time required for a short steel column section to reach the design temperature effective thermal conductivity of the fire protection material characteristic value of effective conductivity of the fire protection material mean value of p calculated from all the short column sections at a temperature SC standard deviation of p calculated from all the short column sections at a temperature SC
Cn(
constant derived for short section at temperature ()
K
constant applied to
4
Test equipment
4.1
General The furnace and test equipment shall conform to that specified in EN 1363-1.
4.2
Furnace The furnace shall be designed to permit the dimensions of the test specimens to be exposed to heating, be they short columns, tall columns or beams, to be as specified in 6.2 and their installation upon or within the test furnace to be as specified in clause 7.
4.3
Loading equipment Loading shall be applied according to EN 1363-1. The loading system shall permit loading to be applied to beams as specified in 5.2.1 and to columns as specified in 5.2.3.
5
Test conditions
5.1
General A number of short steel, "I" or "H" test sections, protected by the fire protection system, is heated in a furnace according to the protocol given in Figures 2, 3 and 4. Loaded and unloaded beams or columns (see Table 1) that are likewise heated provide information on the ability of the fire protection system to remain intact and adhere to the steel test sections (stickability). The method of testing loaded beams in this part of the test method is designed to provide maximum deflection under the influence of load and heating. It is recommended that the tests be continued until the steel temperature reaches the maximum value commensurate with application of the data, usually 750 °C.
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ENV 13381-4:2002 (E)
Where several test specimens are tested simultaneously, care shall be taken that each is adequately and similarly exposed to the specified test conditions. The procedures given in EN 1363-1 shall be followed in the performance of this test unless specific contrary instructions are given.
5.2
Support and loading conditions 5.2.1
Loaded beams
Each loaded beam test specimen shall be simply supported and allowance shall be made for free expansion and vertical deflection of the beam. The simply supported span shall be not greater than the length exposed to heating by more than 250 mm at each end. Loading shall be uniformly and symmetrically applied at two or more locations along its length. Point loads shall be applied directly via loading spacers introduced through the cover slabs, see Figure 5. These spacers may be of any suitable material but if they are of steel or other high conductivity material, unless the contact surface at each loading point is less than or equal to 100 mm × 100 mm or 10 000 mm2, they shall be insulated from the steel beam by a suitable insulation material. 5.2.2
Unloaded beams
Each unloaded beam test specimen shall be supported as shown in Figure 6. 5.2.3
Loaded columns
For each loaded column provision shall be made for the proper support, positioning and alignment of the column test specimen in the furnace and for ensuring uniform distribution of the loading over the ends of the specimen, see Figure 7. The ends of the specimen shall be designed and detailed for the proper transmission of the test load from the loading platens to the specimen. The loadbearing faces at top and bottom of the column shall be parallel to each other and perpendicular to the axis of the column to avoid introduction of bending moments. For protection of the loading equipment against heat, provision shall be made for the attachment of collars at each end of the test specimen. These shall be designed to locate the column and to provide an adequate seal with the furnace walls and shall be suitably attached and supported so that they remain effective and in position throughout the heating period. The method adopted to provide the seal shall allow the test specimen to move within the furnace walls without significantly affecting the load transmitted from the loading rig to the specimen or the fixity at the ends of the specimen. 5.2.4
Unloaded columns
A tall column test specimen or short column section test specimens shall be supported vertically within the furnace, either installed to the soffit of the furnace cover slabs, (see Figure 8), or stood, directly or on plinths, on the furnace floor.
5.3
Loading The loaded beam test specimens shall be subjected to a total load which represents 60 % of the design moment resistance, according to ENV 1993-1-1, calculated using the nominal steel strength and the recommended boxed values given in ENV 1993-1-1. The actual load applied shall be the calculated total load less the dead weight of the beam, concrete topping and fire protection material etc. 9
ENV 13381-4:2002 (E)
The method of loading shall be by a system which will produce a bending moment which is uniform over at least 25 % of the span of the beam around mid-span. The loaded column shall be subjected to an axially applied test load which represents 60 % of the design buckling resistance, according to ENV 1993-1-1, calculated using the nominal steel strength and the recommended boxed values given in ENV 1993-1-1. Details of the calculation made to define the test loads shall be included in the test report.
6
Test specimens
6.1
Number of test specimens 6.1.1
General
The standard package of short steel column test sections appropriate to each assessment method, chosen to span the full range of steel section factors which are in general usage, together with section dimensions, are given in Tables 2, 3 and 4. For both the maximum and the minimum thickness of the fire protection system, a loaded beam shall be tested to examine stickability during maximum deflection of the steel section, up to a maximum anticipated steel temperature. For each test involving a loaded beam, an equivalent unloaded beam section shall be included and tested in the furnace at the same time. Where the range of thicknesses for the fire protection system is such that the difference between the maximum and the minimum thickness is less than 50 % of the minimum thickness, then only a single loaded and unloaded beam or column at the maximum fire protection material thickness need to be tested. 6.1.2
Passive fire protection systems
If the assessment is to be made for both three and four sided application of the fire protection system to both beams and columns, then two loaded beams and two unloaded beams and a number of short steel column sections shall be tested, (see Figures 2, 3 and 4). The minimum number of short steel column sections to be tested is 10. The number may be increased to 18 or 26 in order to satisfy the criteria for validity of the results from the assessment method. If the assessment is to be confined to four sided protection of columns, the two loaded beam tests shall be replaced by two loaded column tests, one with maximum and one with minimum thickness of applied fire protection material. The two unloaded beam tests are not required. 6.1.3
Reactive fire protection systems
If the assessment is to be made for both three and four sided application of the fire protection system to beams and columns, the number of test specimens required is the same as for passive fire protection materials plus an additional test upon a single unloaded column of two metre height minimum, (named a tall column hereafter). This column shall be tested with maximum thickness of fire protection material. If the assessment is to be confined to four sided protection of columns, the two loaded beam tests shall be replaced by two loaded column tests, one with maximum and one with minimum thickness of applied fire protection material. The two unloaded beam tests are not required. The additional tall column is not required, since adequate data would be obtained from the behaviour of the fire protection material upon the two loaded columns. These column tests are required to provide information on stickability and the ability of the reactive fire protection material to resist slumping and flowing. 10
ENV 13381-4:2002 (E)
6.1.4
Precautions against erroneous results
In the event that there should be a loss of valid results from the package of short steel sections tested, (through failure of thermocouples, abnormal behaviour of fire protection etc), then the conditions given in 11.1 shall be applied and a further number of short steel sections may be required to be tested.
6.2
Size of test specimens 6.2.1
Loaded beam test sections
Loaded beam test sections shall have an "I" cross sectional shape, a section height of (400 ± 20) mm and a profiled section factor of (150 ± 10) m-1 (boxed section factor of (110 ± 10) m-1). Each beam shall have a total length which shall provide for a length exposed to heating of not less than 4 000 mm. The supported length and specimen length shall be specified as follows: The span between the supports [Lsup] shall be the exposed length plus up to a maximum of 250 mm at each end. The length of the specimen [Lspec] shall be the exposed length plus up to a maximum of 350 mm at either end (see Figure 5). The additional length, required for installation purposes, shall be kept as small as practically possible. 6.2.2
Unloaded beam test sections
Each unloaded beam test section shall be taken from the same length of steel as its equivalent loaded beam, thereby ensuring that it is of the same dimensions and characteristics. The length of each unloaded beam shall be (1 000 ± 50) mm. 6.2.3
Loaded column test sections
The loaded column test sections shall be of overall dimensions (300 ± 10) mm × (300 ± 10) mm with a profiled section factor of (150 ± 10) m-1. [Boxed section factor of (100 ± 10) m-1]. It shall have a minimum height, exposed to heating, of 3 000 mm. 6.2.4
(Unloaded) Tall column test sections
The (unloaded) tall column test sections shall be of overall dimensions (300 ± 10) mm × (300 ± 10) mm with a profiled section factor of (150 ± 10) m-1 (boxed section factor of (100 ± 10) m-1). It shall have a minimum height of 2 000 mm. 6.2.5
Short column test sections
The short column sections shall have a height of (1 000 ± 50) mm. The short column test sections equivalent to the loaded or tall column test sections shall be taken from the same length of steel, thereby ensuring that they have the same dimensions and characteristics.
6.3
Construction of steel test specimens 6.3.1
Loaded beam test sections
Steel test sections used in loaded beam tests shall be constructed according to Figure 5. To give web stiffness and torsional restraint, the beams shall be provided with: 11
ENV 13381-4:2002 (E)
a)
web stiffeners in the form of steel plates, welded at each loading point. These shall be of thickness at least equal to the thickness of the web and of depth at least 10 mm less than the beam flange depth. Details are shown in Figure 9;
b) web stiffeners in the form of steel plates or channels, welded at each support point. These shall be of thickness at least equal to the thickness of the web. Web stiffeners comprising steel plates shall be trapezoidal in shape to provide additional torsional restraint. Details are shown in Figure 9. 6.3.2
Unloaded beam test sections
Steel test sections used in unloaded beam tests shall be constructed according to Figure 6. To minimize heat transfer at the ends of the unloaded beams, the ends shall be protected with insulation board or similar which at elevated temperatures is capable of providing an equivalent insulation to at least twice that of the particular thickness of the fire protection material provided over the length of the test specimen, (see Figure 6). The linear dimensions of the end protection shall be greater than the total overall dimensions measured over the fire protected steel member. Arrangements shall be made to ensure that any gaps caused by expansion of the steel beam in a boxed fire protection system are closed with fire resistant packing. 6.3.3
Loaded column test sections
Steel test sections used in a loaded column test shall be constructed according to Figure 7. 6.3.4
Unloaded tall column test section
Steel test sections used in an unloaded column test shall be constructed according to Figure 8. When the test is to be carried out on an unloaded tall column section, provision shall be made to minimize heat transfer from the exposed end. The exposed ends shall be protected with insulation board or similar which at elevated temperatures is capable of providing an equivalent insulation to at least twice that of the particular thickness of the fire protection material provided over the height of the column. The linear dimensions of the end protection shall be greater than the total overall dimensions of the fire protected steel section, (see Figure 8). Arrangements shall be made to ensure that any gaps caused by expansion of the steel column in a boxed fire protection system are closed with fire resistant packing. 6.3.5
Short steel column test sections
Steel test sections used in a loaded column test shall be constructed according to Figure 8. To minimize heat transfer from the ends of short steel column sections, the ends shall be protected with insulation board or similar material as specified in 6.3.4 and Figure 8. 6.3.6
Application of the fire protection material to the steel test section
The surface of the steel shall be prepared and the fire protection system shall be applied to the beams and to the columns in a manner representative of practice. The method of application to columns shall not be significantly different to that for beams, otherwise separate tests and assessment shall be needed incorporating loaded columns. Any variability of density of the fire protection system applied to the loaded and equivalent unloaded beams shall be within the limits specified in 6.5.2. For boxed fire protection systems the loaded beams and tall steel column section shall incorporate examples of all constructional and peripheral joints of the design and spacing intended in practice. The fire protection system shall be supported from the steel test section or the concrete deck as appropriate. Where the fire protection system is to be fixed to the lightweight concrete deck by artificial means, e.g. bolting through, the laboratory in carrying out the assessment shall make reference to expected performance if supported from normal concrete. 12
ENV 13381-4:2002 (E)
The fire protection material shall be applied to loaded steel test sections before the load is applied. The fire protection material shall extend beyond the heated length and to within 50 mm of the supports of each loaded beam and shall extend the full height of each column section. Where the fire protection system is of the box type, the ends of the cavity between the material and the steelwork shall be sealed at the point where the test specimen exits the furnace wall to prevent any flow of gases beyond the heated length of the specimen (see Figure 10). Care shall be taken to ensure that during installation of the test specimens into the furnace, or as a result of any movement of the test specimens during the test, the fire protection system is not subjected to any expansion or restraint stresses contrary to its use in practice.
6.4
Composition of test specimen component materials 6.4.1
Steel sections
The steel beams shall be of "I" cross section and the columns of "H" cross section. The grade of steel used shall be any structural grade (S designation) to EN 10025 or EN 10113, (excluding S 185). Engineering grades (E designation) shall not be used. 6.4.2
Fire protection system
The composition of the fire protection system shall be specified by the sponsor and shall include, at least, its expected nominal density, moisture content and heat capacity. For confidentiality reasons the sponsor may not wish detailed formulation or composition details to be reported in the test report. Such data shall, however, be provided and maintained in confidence in laboratory files.
6.5
Properties of test specimen component materials 6.5.1
Steel
The dimensions and cross-sectional areas of the steel sections shall be measured, neglecting any internal and external radii. These values shall be used to determine the steel section factors, according to the equations given in Figure 1, which shall then be used to calculate the applied load according to 5.3. 6.5.2
Fire protection materials
6.5.2.1
General
The actual thickness, density and moisture content of the fire protection material shall be measured and recorded at the time of test for each test specimen. The properties of materials shall be determined on test materials or test samples conditioned as defined in clause 8. The procedures appropriate to different types of fire protection material are given in annex C. 6.5.2.2
Thickness of fire protection materials
The thickness of panel or board type fire protection materials should not deviate by more than 15 % of the mean value over the whole of its surface. The mean value shall be used in the assessment of the results and in the limits of applicability of the assessment. If it deviates by more than 15 % then the maximum thickness recorded shall be used in the assessment. The thickness of sprayed or coated passive and reactive fire protection materials shall be measured at the locations specified in C.2.4. Thickness measuring points shall not be closer than 150 mm to web stiffeners in loaded beams. 13
ENV 13381-4:2002 (E)
The thickness of sprayed fire protection materials and coatings of thickness greater than 5 mm should not deviate by more than 20 % of the mean value. The mean value shall be used in the assessment of the results and in the limits of applicability of the assessment. If it deviates by more than 20 % then the maximum thickness recorded shall be used in the assessment. For sprayed fire protection materials and coatings of thickness less than 5 mm then permitted thickness tolerances (assuming normal distribution of measured thickness) shall be as follows: a) at the temperature measuring stations: A minimum of 68 % of readings shall be within ± 20 % of the mean. A minimum of 95 % of readings shall be within ± 30 % of the mean. All readings shall be within ± 45 % of the mean. b) overall: A minimum of 68 % of readings shall be within ± 20 % of the mean at the temperature measurement stations. A minimum of 95 % of readings shall be within ± 30 % of the mean at the temperature measurement stations. All readings shall be within ± 45 % of the mean at the temperature measurement stations. If the thickness is outside these limits the test specimens shall be rejected and replaced. The mean thickness (or maximum thickness according to the above criteria for permitted deviation in thickness) of fire protection material applied to each loaded beam and to the tall steel column section, where used (loaded or not), shall be the same as that applied to its equivalent unloaded beam or short steel column section. The difference between the thickness in each case shall not be greater than 10 % of the maximum value or ± 5 mm, which ever is the lesser. 6.5.2.3
Density of fire protection materials
The density of the fire protection material (where appropriate) applied to each loaded beam, unloaded beam, loaded column and tall column section (where used) and short column section shall be measured according to annex C and recorded. At each thickness of fire protection material, the density of each should not deviate by more than 15 % of the mean value. The mean value shall be used in the assessment of the results and in the limits of applicability of the assessment. If it deviates by more than 15 % then the maximum density recorded shall be used. The mean density of fire protection material (or maximum density according to the above criteria for permitted deviation in density) applied to each loaded beam and to the tall steel column section, where used (loaded or not), shall be the same as that applied to its equivalent unloaded beam or short steel column section. The difference between the density in each case shall not be greater than 10 % of the maximum mean value at that thickness. 6.6
Verification of the test specimen An examination and verification of the test specimen for conformity to specification shall be carried out as described in EN 1363-1. The properties of the fire protection materials used in the preparation of the test specimens shall be measured, using special samples where necessary, using the methods given in annex C. The sponsor shall be responsible for verification that the fire protection material has been applied correctly and in the case of sprayed or coated materials, to ensure, by methods appropriate to the material, that it is of design composition and specification.
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7
Installation of the test specimens
7.1
Loaded beam A lightweight concrete topping shall be provided, such that only the two sides and the soffit of the beams are exposed to heating, as shown in Figure 5. The elements of the lightweight concrete topping shall be of 100 mm minimum thickness, of 600 mm maximum length, measured along the beam and of (600 ± 100) mm width, measured across the beam and be of density not more than 650 kg/m3. There shall be a layer of compressible ceramic fibre insulation material placed between the lightweight concrete and the top flange of the beam. This insulation material shall have an uncompressed thickness of (30 ± 5) mm and a nominal density of (125 ± 25) kg/m³. This insulation shall have a width equal to the width of the top flange of the steel beam (see Figure 11). The elements of the lightweight concrete topping shall be secured to the beam by bolting to 10 mm diameter studs welded to the beam. There shall be a 100 mm × 100 mm × 6 mm steel plate beneath the locking nut. These studs may be situated within the junction between each element of the concrete topping, or within the length of the concrete topping, (see Figure 5: fixing within the length of the topping shown). Each element of the concrete topping shall be secured by at least two fixings. The gap between the elements of the concrete topping shall be filled with fire resistant packing. At the commencement of the test the soffit of the concrete topping to the loaded beam shall be nominally flush with the soffit of the adjacent furnace cover slabs. Arrangements, appropriate to laboratory practice, shall be made to ensure that the gap between the concrete topping to the loaded beam and the adjacent furnace cover slabs is sealed to prevent escape of furnace gases, especially when the beam is subject to deformation during the test. The loaded beam shall be installed, with special attention taken to insulate the bearings of the beam from the influence of heat (see Figure 10).
7.2
Unloaded beam Each unloaded beam test specimen shall be bolted to the soffit of the furnace cover slabs comprising the same concrete as that used as topping to the loaded beam, using 10 mm diameter studs welded to the beam. There shall be a 100 mm × 100 mm × 6 mm steel plate beneath the locking nut. Each specimen shall be provided with a layer of ceramic fibre insulation board placed between the soffit and the top flange of the beam as specified in 7.1 for the loaded beam and Figure 6.
7.3
Loaded columns A loaded column test specimen shall be installed as given in Figure 7.
7.4
Unloaded columns A tall column test section or short column test sections shall be either installed to the soffit of the furnace cover slabs, using 10 mm diameter studs welded to the column section and 100 mm × 100 mm × 6 mm plates beneath the locking nut (see Figure 8), or stood, directly or on plinths, on the furnace floor. A slab of ceramic fibre insulation board of thickness (10 ± 1) mm and density (350 ± 50) kg/m3 shall be used between all contact surfaces of the steelwork and the cover slab or the furnace floor or plinth. The linear dimensions of the fire insulation board shall be greater than the total overall dimensions of the fire protected steel section, (see Figure 8).
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7.5
Test specimen installation patterns Each loaded beam test specimen and its equivalent unloaded beam section shall always be installed within the furnace at the same time and tested together in order to provide an accurate comparison. Short steel column sections may also be included within the furnace at the same time as loaded and unloaded beams. The number of short column sections included will depend upon the capacity of the furnace with the proviso that short column sections shall be separated one from the other such that they are all subjected to the standard heating conditions on all faces. When testing a loaded column section it is also desirable to include the equivalent short column section within the furnace at the same time. A typical test specimen installation pattern useable in a 4 m × 3 m furnace is given in Figure 12.
8
Conditioning of the test specimens All test specimens, their components and any test samples taken for determination of material properties shall be conditioned in accordance with EN 1363-1.
9
Application of instrumentation
9.1
General The instrumentation for measurement of temperature, furnace pressure, applied load and deformation shall comply with the requirements of EN 1363-1.
9.2
Instrumentation for measurement of furnace temperature 9.2.1
General
Plate thermometers, of the type specified in EN 1363-1, shall be provided to measure the temperature of the furnace and shall be uniformly distributed, as given in EN 1363-1, to give a reliable indication of the temperature in the region of the test specimens. 9.2.2
Furnace temperature in the region of beam test specimens
The furnace temperature in the region of each loaded beam test specimen shall be measured by a total of eight plate thermometers, placed at locations at 1/5, 2/5, 3/5 and 4/5 of the heated length of the loaded beam, there being two plate thermometers at each location, one on each side of the beam. The plate thermometers shall be oriented so that for half their number side 'A' faces the floor of the furnace and for the other half, side 'A' faces the longer side walls of the furnace. The distribution of the different orientations shall be such that there shall be equal numbers facing the floor and the wall on each side of the beam. The furnace temperature in the region of each unloaded beam test specimen shall be measured by two plate thermometers, placed at the midpoint of the length exposed to heating of the unloaded beam, one on each side of the beam. One plate thermometer shall be oriented so that side 'A' faces the floor of the furnace and the other so that side 'A' faces the nearest longer side wall of the furnace. At the commencement of the test these thermocouples shall be positioned and maintained throughout the test as specified in EN 1363-1 and shown in Figure 13.
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9.2.3
Furnace temperature in the region of column test specimens
The furnace temperature in the region of each column section test specimen shall be measured using two plate thermometers placed, on either side of the column, at each of the following locations:
for a loaded column at 1/4, 1/2 and 3/4 column height, for a tall column at mid-height, for a short column section at mid-height.
The plate thermometers shall be oriented so that side 'A' faces the side walls of the furnace. The insulated parts shall face towards the column. At the commencement of the test the hot junctions of these thermocouples shall be positioned and maintained throughout the test as specified in EN 1363-1.
9.3
Instrumentation for measurement of steel temperatures 9.3.1
General
Thermocouples for measurement and recording of steel temperatures, of the type and fixing given in annex D, shall be located at measurement stations as specified below (see 9.3.2 to 9.3.6). Each measurement station shall comprise five thermocouples, four fixed to the flanges and one fixed to the web of the steel beam. The four thermocouples on the flanges shall each be fixed mid-way between the toe of the flange and the web, the thermocouple on the web shall be fixed mid-way between the two flanges, (see Figure 9). 9.3.2
Loaded beam test specimens
For each loaded beam test specimen there shall be five measurement stations at 1/4, 3/8, 1/2, 5/8 and 3/4 of the length of the beam exposed to heating (see Figure 9). Temperature measuring points shall be separated from loading points by at least 150 mm and shall not be closer than 150 mm to web stiffeners. The thermocouples on the web shall be positioned on alternate sides of the web. Additional six thermocouples shall be fixed to the upper surface of the bottom flange of each beam test specimen, positioned one midway between each measurement station, and one midway between each outermost measurement station and the final exposed extremity of the beam, (see Figure 9). 9.3.3
Unloaded beam test specimens
For each unloaded beam test specimen there shall be two measurement stations, at 1/3 and 2/3 of the length of the beam. At each measurement station an additional thermocouple shall be placed on the web such that thermocouples are situated on both sides of the web, (see Figure 6). 9.3.4
Loaded column test specimens
For each loaded column test specimen there shall be a measurement station located at a distance of 200 mm from the top of the column and also at 1/6, 1/3, 1/2, 2/3 and 5/6 of the heated length of the column (see Figure 7). Thermocouples on the web shall be positioned on alternate sides of the web. 9.3.5
Unloaded tall column test specimen
For each unloaded tall column test specimen there shall be a measurement station located at a distance of 200 mm from the top of the column and at 1/6, 1/3, 1/2, 2/3 and 5/6 of the length of the column, exposed to heating, (see Figure 8). Thermocouples on the web shall be positioned on alternate sides of the web.
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9.3.6
Short column test specimens
For each short column test specimen there shall be a measurement station located at a distance of 200 mm from the top of the column and also at mid-height of the column, (see Figure 8). Thermocouples on the web shall be positioned on alternate sides of the web.
9.4
Instrumentation for the measurement of pressure Equipment for measuring pressure within the furnace shall be provided, located and used as specified in EN 1363-1.
9.5
Instrumentation for the measurement of deformation For loaded beams a suitable means of measuring the vertical deformation at mid-span relative to the supports and for loaded tall steel columns a suitable means of measuring the axial deformation shall be provided, located and used as specified in EN 1363-1.
9.6
Instrumentation for the measurement of load Instrumentation for the measurement of applied load shall be provided and used as specified in EN 1363-1.
10
Test procedure
10.1
General Assemble the required number of loaded beams, unloaded beams and column sections forming the testing package appropriate to the assessment method to be used as detailed in Tables 1, 2, 3 and 4. Incorporate these in several tests according to the capacity of the furnace and the criteria of 7.5. Conduct tests on a loaded beam and its equivalent unloaded beam together for reference purposes. Carry out checks for thermocouple consistency and establish data points for temperature as specified in EN 1363-1 before commencement of the test and the procedures defined in 10.2 to 10.7.
10.2
Furnace temperature and pressure Measure and record the furnace temperature in the region of each test specimen using the plate thermometers defined in 9.2 and the furnace pressure in accordance with EN 1363-1. Control the furnace temperature using the eight plate thermometers located in the region of the loaded beam, as specified in 9.2.2, to the criteria of EN 1363-1. If testing, simultaneously, loaded beam(s), unloaded beam(s) and unloaded columns, control the furnace temperature using those plate thermometers located in the region of the unloaded column sections as specified in 9.2.3, to the criteria of EN 1363-1. If testing, simultaneously, loaded columns and/or unloaded tall and/or short columns, control the furnace temperature using those plate thermometers located in the region of the unloaded short column sections as specified in 9.2.3, to the criteria of EN 1363-1. When testing loaded columns only, control the furnace temperature using the six plate thermometers specified in 9.2.3. Control the furnace pressure to the criteria of EN 1363-1.
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10.3
Application and control of load 10.3.1
Loaded beams
Using the procedures of EN 1363-1 apply a constant load to the loaded beam, of magnitude derived in accordance with 5.3, throughout the test period until a deformation of Lsup/30 is reached, at which point, the load shall be removed. If after 4 h test duration a deformation of Lsup/30 has not been attained, the applied load may be increased in stepwise increments of 2 % of the original test load, for each additional 1 min of test time, until a deformation of Lsup/30 is reached. The test shall then be continued, with adjustment of the test load as necessary to maintain that deformation, for an additional period of 15 min. 10.3.2
Loaded columns
Where a loaded column is tested, apply a constant load throughout the test period until either of the following is exceeded: -
a limiting axial contraction of h/100; or
-
a limiting rate of axial contraction 3h/1000
at which point the load shall be removed
10.4
Temperature of steelwork Measure and record the temperature of the loaded and unloaded beams and short column sections (and loaded columns and tall columns where used), using the thermocouples attached to the steelwork as specified in 9.3 at intervals not exceeding 1 min.
10.5
Deformation Identify an initial deformation datum point, relative to the supports, before application of the test load. Then, using the procedures of EN 1363-1, apply the test load, measure the zero point for deformation and monitor the deformation of the loaded steel beam and the axial contraction of the loaded tall steel column section, if used, continuously throughout the test, at intervals not exceeding 1 min.
10.6
Observations Monitor the general behaviour of each of the specimens throughout the test and record the occurrence of cracking, fissuring, delamination or detachment of the fire protection material and similar phenomena as described in EN 1363-1.
10.7
Termination of test Continue each test until the mean temperature recorded on all the steel sections exceeds the recommended termination temperature, normally 750 °C, and the duration of the test exceeds the maximum fire resistance period for which the sponsor requires approval. These limits may be modified at the request of the sponsor. Otherwise terminate the test when one or more of the reasons for termination which are specified in EN 1363-1 occur. 19
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11
Test results
11.1
Acceptability of test results It is possible that within any test package apparently erroneous results may occur through failure of thermocouples, abnormal behaviour of fire protection, incorrect assembly of the test specimen etc. If any results are to be disregarded, the laboratory, in consultation with the sponsor, shall justify this and apply the following rules: Loaded beams: - from the 10 thermocouples on the upper flange at least six results shall be valid and in close agreement - from the 5 thermocouples on the web at least three results shall be valid and in close agreement - from the 16 thermocouples on the lower flange at least 12 results shall be valid and in close agreement Unloaded beams: - from the 4 thermocouples on the upper flange at least two results shall be valid and in close agreement - from the 4 thermocouples on the web at least two results shall be valid and in close agreement - from the 4 thermocouples on the lower flange at least two results shall be valid and in close agreement Loaded and tall columns: - from the 30 thermocouples on the column at least 20 results shall be valid and in close agreement, with at least two valid results at each temperature measurement station. Unloaded short columns: - from the 10 thermocouples on the column at least six results shall be valid and in close agreement. In the case of doubts on validity for reasons other than thermocouple failure, the laboratory shall decide upon the validity of the result and justify the decision. A minimum number of short columns are required to give valid results for a meaningful assessment. These are as follows: When the requirement is for 10 short sections to be tested, a minimum of nine short column section results shall be valid. When the requirement is for 18 short sections to be tested, a minimum of 16 short column section results shall be valid. When the requirement is for 26 short sections to be tested, a minimum of 22 short column section results shall be valid. When the number of valid short column data points obtained does not meet these requirements, the erroneous data which have been disregarded from the test package shall be replaced by repeat testing.
11.2
Presentation of test results The following shall be reported within the test report: a) the results of measured dimensions and actual material properties, especially the thickness, density and moisture contents of the fire protection together with those values to be used in the assessment, according to 6.5, b) the individual results of all furnace temperature measurements and the mean of all individual furnace temperature measurements, taken as specified in EN 1363-1, graphically presented and compared with the
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specified requirements and tolerances given in EN 1363-1, c)
the individual results of all furnace pressure measurements and the mean of all individual furnace pressure measurements, taken as specified in EN 1363-1, graphically presented and compared with the specified requirements and tolerances given in EN 1363-1,
d) the individual results and the mean of all individual results of all steel temperature measurement thermocouples at equivalent locations given in 9.3, all graphically presented. Evidence of compliance with the validity criteria of 11.1, e)
the individual results and the mean of all individual results of all the deformation measurements on loaded beams specified in 10.5, all graphically presented. If the load is removed according to 10.3.1, the time at which this occurred,
f)
the individual results and the mean of all individual results of all the axial contraction measurements on loaded columns specified in 10.5, all graphically presented. If the load is removed according to 10.3.2, the time at which this occurred. These results b) to f) may be presented as a selection of the measured data sufficient to give a history of the performance of the test specimen according to EN 1363-1. These results b) to f) may also be prepared and printed in tabular form and/or presented upon computer diskette. In the latter case this should be prepared in an appropriate, secure "read only" format to prevent alteration. The only legally genuine data shall be those data maintained in the laboratory files,
g) the results of observations made and times at which they occur shall be reported.
12
Test report
12.1
General The test report shall include the following statement. "This report provides the constructional details, the test conditions, the results obtained and the interpolated data obtained when the specified fire protection system described herein was tested following the procedures of ENV 13381-4. Any deviation with respect to thickness and density of fire protection material and constructional details, loads, stresses edge or end conditions other than those allowed under the field of application could invalidate the test result". In addition to the items required by EN 1363-1, the following shall also be included in the test report: a) the generic description and accurate fixing details of the fire protection system; b) full details of the test specimens including assembly and preparation details including surface preparation; c)
the results of the measurements obtained using the measurement devices in 11.2 f) during the tests presented in graphical format (and any other optional format), as required in 11.2;
d) a description of significant behaviour of the test specimen observed during the test period, including observations of the time(s) and magnitude of any detachment of fire protection material; e)
the magnitude of the load applied to each test specimen, as a function of time, and if removed (loaded beams and columns), the time at which this occurred;
f)
the reason, on the basis of 10.7 of this test method, for the termination of the test and the time elapsed when the test was terminated;
g) the results of any test carried out using the smouldering fire (slow heating curve) as described in annex A. 21
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13
Assessment
13.1
General The temperature data obtained from the short steel columns only are used as a basis for relating the time to reach a specified steel temperature, the thickness of fire protection material and section factor. The result is corrected using correction factors, indicative of stickability, obtained by direct comparison of loaded and unloaded specimens. The first analysis of data shall normally be made on the basis of either differential equation or numerical regression methods. An alternative analysis of the data may be made, usually after the first, by a graphical presentation method. Each individual assessment methodology requires and specifies a minimum number of data points for interpolation. There is no single method of calculation that can be applied to all types of fire protection system. For each test, the most appropriate method shall be determined from the acceptability of the analysis which shall be judged against defined criteria, (see Figure 4). Generally the result is considered to be applicable to "I" and "H" steel sections with three and four sided exposure of the steel section to fire, subject to a check on the compatibility of the data from both being made. If there is a large discrepancy, then the application could be limited and/or further testing will be required. Throughout this document the assumption is made in the text that the test and assessment package relates to three and four sided application of the fire protection material to beams and columns and the specimens tested shall be as given in 6.1. For three and four sided protection, with a Passive fire protection system, the assessment shall be based upon data obtained from testing two loaded beams, two unloaded beams and a package of short columns. For three and four sided protection, with a Reactive fire protection system, the assessment shall be based upon data obtained from testing two loaded beams, two unloaded beams, a tall unloaded column and a package of short columns. If the assessment is to be confined to 4 sided application of columns with a Passive or a Reactive fire protection system, the assessment shall be based upon data obtained from testing two loaded columns and a package of short columns. This clause refers only to loaded beams. Where loaded columns are to be used the appropriate text and symbols should be adopted (i.e. columns replaces beams, LC replaces LB, LC replaces LB, k(LC) replaces k(LB), kd(LC) replaces kd(LB) etc.).
13.2
All fire protection systems 13.2.1 General The data from the loaded sections will possibly need to be corrected for localized high temperatures (see 13.2.2). The data from an unloaded section shall be corrected for any discrepancies between the thickness of fire protection material applied to it and that applied to its equivalent loaded section (see 13.2.3), prior to obtaining a correction factor k() which relates to stickability (see 13.2.4). From a comparison of each loaded section and its equivalent unloaded short section any variation of k() with thickness, kd(), shall be derived. The temperature data from the short steel column sections only shall be used as a basis for the evaluation of the fire protection system. These data shall be corrected for stickability according to the procedures given in 13.2.4 and subject to the assessment protocol given in Figure 4.
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13.2.2 Temperature of steel sections From the temperature data collected and reported in 11.2 and clause 12, the following shall be determined for each of the sets of thermocouples located on the top flange, the web and the bottom flange of loaded and unloaded beams (similar data shall be determined for columns). -
graphs of the mean of all individual temperatures, graphs of the individual thermocouples giving rise to the maximum temperature.
For each loaded and unloaded beam, an overall mean value and a maximum value of temperature at all steel locations is determined, from the values determined at each of these individual locations. The results shall be graphically presented according to 11.2 (similar data shall be determined for columns). The steel temperature (LB), (UB), (LC), (TC) or (SC) used for calculation of the correction factor for stickability (see 13.2.4) shall always be the characteristic steel temperature given as the mean of the maximum temperature and the mean overall temperature [(max + mean) ÷ 2)] from all thermocouples, for all time increments. The steel temperature used for the purpose of assessment of thermal performance (see 13.5) shall always be the mean steel temperature (SC) for all time increments. 13.2.3 Correction for discrepancy in thickness Corrections made to data for thickness shall be as shown in annex E. It is not always possible to obtain a precise match between the loaded beam and its equivalent unloaded beam due to difficulties in applying certain types of fire protection material at a precise thickness. To compensate for differences in thickness of fire protection material between a loaded beam and its equivalent unloaded beam, the temperature rise of the unloaded beam section shall be corrected by: -
the method given in a), when the differential equation analysis method (variable approach), as given in 13.5 and annex F, is used as the assessment procedure for thermal performance;
-
the method given in b), when the differential equation analysis method (constant approach) as given in 13.5 and annex G is used as the assessment procedure for thermal performance;
-
the method given in c), when the numerical regression analysis method as given in 13.5 and annex H is used as the assessment procedure for thermal performance;
-
the method given in d), when the graphical presentation method as given in 13.5 and annex J is used as the assessment procedure for thermal performance.
The corrected temperatures (c(UB)) of each unloaded beam, derived in the manner described, shall be used as the basis for the overall corrections on all thermal data as described in 13.2.4. a) Calculate for each of the unloaded beam sections p as a function of time using equation F.2 to give the effective thermal conductivity, p,t (t), using the actual mean thickness (dUB) of the fire protection material on the unloaded beam. Calculate the corrected characteristic temperature (c(UB)) of each unloaded beam, using the basic differential equation F.1, the relevant calculated values for pt and the thickness (dLB) of the fire protection material on the equivalent loaded beam. b) Calculate for each of the unloaded beam sections p for design steel temperatures d from at least 350 °C to 750 °C in 50 °C intervals, using equation G.1 with the actual mean thickness (dUB) of the fire protection material on the unloaded beam. Fit the values of p using the method of least squares and equation G.2 in which factor C2 equals zero. 23
ENV 13381-4:2002 (E)
Calculate the corrected characteristic temperature (c(UB)) of each unloaded beam, using the basic differential equation G.1, the relevant calculated values for pt and the thickness (dLB) of the fire protection material on the equivalent loaded beam. c) Calculate for each of the unloaded beam sections the constants a0 to a7 by solving the basic numerical regression equation H.2, using the actual mean thickness (dUB) of the fire protection material on the unloaded beam. Calculate the corrected characteristic temperature (c(UB)) of each unloaded beam, using the basic numerical regression equation H.2, the calculated constants a0 to a7 and the thickness (dLB) of the fire protection material on the equivalent loaded beam. d) The corrected characteristic temperature (c(UB)) of the unloaded beam shall be calculated using the following relationship:
θ c(UB) = 140 + ( θ UB - 140) × [
d UB 0,77 ] d LB
13.2.4 Correction of temperature data for stickability A correction factor is required to account for the occurrence of local areas of high steel temperature, caused by loss of stickability of fire protection material. This correction factor is derived from comparison of the characteristic temperatures measured on loaded and unloaded beams. If at any time the characteristic steel temperature of each loaded beam exceeds the equivalent characteristic steel temperature of the equivalent unloaded beam it shall be necessary to apply a proportionate correction factor, k(), to all data derived from the short sections prior to carrying out the assessment of thermal performance in accordance with 13.4. The correction factor, k(), shall be calculated at intervals of temperature according to the calculation procedure adopted and which is used in the analysis and prediction procedures. For each loaded beam it is necessary to evaluate the factor k() on the basis of the respective unloaded beam characteristic temperature, or if applicable, on basis of the unloaded beam characteristic temperature corrected for thickness according to 13.2.3, using the relationship:
k( θ ) =
For
θ LB θ c(UB)
θ LB < 1 , k( θ ) = 1 θ c(UB)
Each of the two loaded tests are likely to give rise to different values of k() in which case assume that k() varies linearly with material thickness.
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ENV 13381-4:2002 (E)
( θ ) - k min ( θ ) i.e. k d ( θ ) = k max ( d i - d min ) + k min ( θ ) ( d max - d min ) The resulting values of the correction factor kd() may be plotted against c(UB) to facilitate kd() to be derived for any steel temperature. The mean temperature data from each short steel column section, (SC), shall be modified by applying the appropriate correction factor kd() as follows:m(SC)
= kd() × SC
and all data analysis is then carried out on the basis of the modified mean steel temperatures, m(SC). The same procedure shall be applied for four-sided protection of columns using comparison of the characteristic temperatures on loaded and unloaded columns.
13.3
Reactive fire protection systems 13.3.1 General Certain behavioural characteristics of reactive fire protection systems mean that it is necessary to provide additional test data, relating to stickability, from a test upon a 2 m tall column. The following additional or alternative procedures appropriate to the assessment of the results of tests conducted on reactive fire protection systems shall be used. The results from testing beams or columns may need to be analyzed slightly differently and the results presented separately. 13.3.2 Correction of temperature data for localised high temperature The characteristic steel temperature for calculation purposes for the loaded beam tests (LB), or, where used, loaded columns, (LC), shall be determined as described in 13.2.2. 13.3.3 Correction for discrepancy in thickness Many reactive systems are applied at very low thicknesses and it is important that the temperature data are carefully related to the precise thicknesses of material used. The correction for temperature data given in the following section includes a compensation for any thickness discrepancy between the various steel sections as part of the correction made to the temperature data for stickability. 13.3.4 Correction to temperature data for stickability 13.3.4.1 General For application of the results of the assessment to both three and four sided protection, the temperature data shall be corrected for stickability against either the tall column or the loaded beams. The most worst case result for kd() arising shall be used (see 13.3.5). For application of the results of the assessment to four sided protection only, the temperature data shall be corrected for stickability against loaded columns, using the procedures specified in 13.2.4. 13.3.4.2 Correction for stickability against the loaded beams The temperature data from the unloaded tall column shall be used to derive the correction factor to be applied to the mean temperature data (SC) from all the short column sections as follows: a) From the results obtained from the short steel column sections of size HEA 300 or equivalent, plot at intervals of time appropriate to the requirements of the assessment method, or at maximum of ten minute intervals, the characteristic steel temperature (SC), against thickness of fire protection (dp). 25
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b) From the results of the test on the tall steel column section, determine the characteristic steel temperature of the tall steel column (rc) at equivalent time intervals as used in a) above. c)
For the actual thickness of material applied to the tall steel column section, obtain the interpolated characteristic temperature for the short steel column section (SC) at each time interval.
d) Determine the correction factor kd(rc) at each time interval as follows:
k( θ LB ) =
For
θ LB θ UB
θ LB < 1, k( θ LB ) = 1 θ UB
e)
The resulting value of kd(rc) may be plotted against SC to facilitate kd(rc) to be derived for any steel temperature.
f)
The mean temperature data from each short steel column section (SC) shall then be modified by applying the appropriate correction factor as follows: m(SC) = kd(LB) × SC All data analysis shall be carried out on the basis of the modified mean steel temperatures, m(SC).
13.3.4.3 Correction for stickability against the tall column The temperature data from the unloaded tall column shall be used to derive the correction factor to be applied to the mean temperature data (SC) from all the short column sections as follows: a) As for the tall column (see 13.3.4.2), plot at intervals of time appropriate to the requirements of the assessment method, or at a maximum of ten minute intervals, the characteristic temperature of the short HEA 300 columns (SC), or their equivalent, against the thickness of the fire protection (dp). b) From the results of each unloaded beam, determine the characteristic temperature (UB) at equivalent time intervals as in a). c)
For each unloaded beam, and at each time interval, adjust the position of the curve given by a) such that it passes through the point given by the thickness and characteristic temperature for the unloaded beam. Maintain the shape of the curve.
d) From the results of each loaded beam test, determine the characteristic temperature of the beam (LB) at each time interval.
26
e)
For the actual thickness of material applied to each loaded beam, obtain the interpolated characteristic temperatures of the unloaded beam (UB) at each time interval.
f)
Determine for each loaded beam, the factor kd(LB) at each time interval as follows:
ENV 13381-4:2002 (E)
k d ( θ LB ) = θ LB / θ UB For
θ LB < 1, ( k d θ LB ) = 1 θ UB
g) Each loaded beam test is likely to give rise to different values of k(LB) in which case, assume that k()LB varies linearly with material thickness and derive the correction factor kd(LB) as given in 13.2.4 and plot it against UB to facilitate kd(LB) to be derived for any steel temperature. h) The mean temperature data from the short steel column section (SC) shall then be modified by applying the appropriate correction factor as follows: m(SC) = kd(LB) × SC All data analysis shall be carried out on the basis of the modified mean steel temperatures, (m(SC)).
13.3.5 Choice of kd() For a single assessment covering both three and four sided protection, the highest value between kd(LB) and kd(RC) at any steel temperature shall be used to give the value of m(SC) to be applied.
13.4
Presentation of data to be used in the assessment The data to be used in the assessment and which have been obtained and possibly corrected according to 13.1 and 13.2 or 13.3 shall, if appropriate, be presented in the following order: a)
for loaded sections the appropriate characteristic steel beam temperature (LB) or characteristic steel column temperature (LC), if used, obtained according to 13.2.2 and to 13.3.2;
b) the thickness of the fire protection material applied to each unloaded beam (dUB) as specified in 13.2.3; c)
the characteristic temperature (UB) of the unloaded steel sections, corrected as (c(UB)) if necessary, for differences in thickness of the fire protection material applied to the loaded and unloaded steel beam section, as specified in 13.2.3;
d) the correction factors kd(LB) [and kd(TC) if used], derived from the characteristic steel temperature data on the loaded beam section (or tall column section) and the temperature of the equivalent unloaded beam (or short column) section; e)
13.5
the modified mean temperature data, m(SC), for all short steel column sections having applied the correction factor kd(LB) or kd(RC), if appropriate, to each.
Assessment procedures for thermal performance 13.5.1 General Assessment of thermal performance shall be carried out on the basis of the corrected mean steel temperatures of each short column using one of the following assessment procedures. Each procedure requires a minimum number of short steel column sections to be tested. Criteria for acceptability and limitations on the use of these methods are given within 13.6 and 13.7.
27
ENV 13381-4:2002 (E)
13.5.2 Differential equation analysis method Two alternative procedures may be applied as given in annexes F and G. Each relates to that given in ENV 1993 1-2. In the variable method (annex F) the assessment is carried out over all temperatures. °C and above. A minimum of 10 short steel column sections shall be tested (see Table 2). If further data points are required, additional eight (see Table 3) or 16 (see Table 4) specimens shall be tested. 13.5.3 Numerical regression analysis method The procedure shall be as given in annex H of this test method and uses an analysis of temperature, thickness, section factor and time. The assessment is carried out at temperatures of 350 °C and above. A minimum of 10 short steel column sections shall be tested (see Table 2). If further data points are required, additional eight (see Table 3) or 16 (see Table 4) specimens shall be tested. 13.5.4 Graphical analysis method The procedure shall be as given in annex J of this test method and examines results graphically and defines rules on how lines shall be drawn through points. The assessment is carried out at temperatures of 350 °C and above. A minimum of 18 short steel column sections shall be tested (see Table 3). If further data points are required, additional eight (see Table 4) specimens shall be tested.
13.6
Acceptability of the assessment method used and the resulting analysis 13.6.1 Criteria for acceptability The acceptability of the analysis within the range of steel section temperature (350 °C and upwards as defined by 10.7 or the sponsor) and duration of the test shall be judged up to the maximum temperature tested on the following basis: a)
For each short column section the predicted time to reach the design temperature shall not exceed the time for the corrected temperature to reach the design temperature by more than 30 %.
b) The mean value of all percentage differences as calculated in a) shall be less than zero. c)
A maximum of 20 % of individual values of all percentage differences as calculated in a) shall be more than zero.
13.6.2 Modification of the analysis Modification of the analysis may be made by one of the following methods. a)
Differential equation method (variable and fixed methods): If the criteria detailed in 13.6.1 are not satisfied, the analysis may be repeated using the procedures given in annexes F and G.
b) Numerical regression analysis: If the criteria detailed in 13.6.1 are not satisfied, the analysis may be repeated using the procedures given in annex H. 28
ENV 13381-4:2002 (E)
13.7
Three and four sided exposure If the results of the assessment are based on the testing of loaded beams only, without a tall steel column section test, the results of the analysis may be applied to four sided use of the fire protection system on beams or columns, subject to meeting the criteria detailed in 13.6. In addition, if the predicted time to reach the design temperature for a loaded beam does not exceed the actual test time by more than 10 % then the results of the analysis are applicable for use with three and four sided protected beams or columns. If the predicted time for an unloaded beam to reach the design temperature exceeds the actual test time by more than 10 % then the analysis for that design temperature may be modified as indicated in 13.6.2. Alternatively, a separate test package involving short steel beam sections may be undertaken to provide further information on steel sections protected on three sides. If the results of the assessment are based on the testing of loaded beams and a tall steel column section, the results of the analysis may be presented for three sided use of the fire protection system, based on a stickability correction to the beams, and for four sided use based on a stickability correction to the tall steel column section, in both cases subject to meeting the criteria detailed in 13.6.
14
Report of the assessment The report of the assessment shall include the following: a) the name/address of the body providing the assessment and the date it was carried out. Reference to the name/address of the test laboratory, the unique test reference number and report number(s); b) the name(s) and address(es) of the sponsor(s). The name of the manufacturer of the product or products and the manufacturer or manufacturers of the construction; c)
the generic description of the product or products, particularly the fire protection system and any component parts (where known). If unknown this shall be stated;
d) general description of the fabrication of the test construction. General description of the fixing details of the fire protection system. General description of the conditioning of the test construction and its installation onto the test furnace; e)
general description of the test specimen with drawings, including the dimensions of the test specimen and photographs and written instructions, provided by the sponsor;
f)
the composition and measured properties, especially density, thickness and moisture content, of test specimen components required to be determined from 6.5 and their method of determination;
g) the assessment method used and the justification for its use; h) characteristic steel temperatures and mean steel temperatures according to 13.2.2, and characteristic steel temperatures corrected for discrepancy in thickness, according to 13.2.3. The values of the correction factors applied to short column steel temperatures to correct for stickability according to 13.2.4 and 13.3.4 and the resulting values of the modified mean temperature for the short column sections used in the assessment of thermal performance; i)
the values of all thermal data required to be calculated by the chosen assessment method;
j)
for the differential equation method (where used), the variation of effective thermal conductivity as a function of temperature, together with the values of Cp and protection used as a basis for the calculation of effective thermal conductivity. Values of the modification coefficient (variable method) or modified values of C0 29
ENV 13381-4:2002 (E)
(constant method) used to satisfy the criteria for acceptability as specified in 13.6; k) for the numerical regression analysis method (where used), values of any simple linear modification factor(s) used to satisfy the criteria for acceptability as specified in 13.6; l)
for the graphical presentation method (where used), an analysis illustrating compliance with the criteria for acceptability as specified in 13.6. Graphical presentations which include: -
for a given design temperature, the time to reach the design temperature as a function of section factor and for alternative thicknesses of fire protection material (see Figure 14);
-
for specified periods of fire resistance, the design temperature as a function of section factor and for alternative thicknesses of fire protection material (see Figure 15);
m) the thermal analysis shall produce a series of tables and graphical presentations relating to fire resistance periods of ¼, ½, 1, 1½, 2, 3, and 4 hours. Each table or graphical presentation shall show the minimum thicknesses of fire protection material required to ensure that design temperatures of 350 °C, 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, 650 °C, 700 °C, 750 °C and higher if necessary are not exceeded on steel members with section factors (Am/V values) at intervals of 20 m-1. (An example of the presentation of such tabulated information is given in Table 5). Any alternative presentation of the data specified by the sponsor appropriate to local needs and different design temperature limits and intervals of section factor; n) the report shall also include a statement regarding the limits of direct application of the assessment procedure, especially with regard to the range of section factors, design temperatures, thicknesses, fire resistance periods, three or four sided protection, etc.
15
Limits of the applicability of the results of the assessment The results from this test method and the assessment procedure are applicable to fire protection systems over the range of fire protection material thicknesses tested, the values of steel section factor Am/V tested and the maximum temperatures established during the test. The fire protection period resulting from the test and assessment is limited to the maximum period of testing or some shorter period. Nominal extension only beyond those variables evaluated during the test is permitted and is dependent on the assessment method used. Permitted extensions according to the assessment method are given in Table 6. The assessment is only applicable to the method of fixing or application used in the test. Any change in the method of fixing/application and any reinforcement of material shall be re-assessed. This would normally require additional tests. The results of the assessment are applicable only to sections of "I" or "H" cross section according to the interpolation method used. The information relates to a minimum section factor of 50 m-1 having been tested. However, irrespective of the permitted extensions allowed above, information derived at any section factor may be applied to steel members having lower section factors. Application of an assessment to other section shapes, e.g. square, rectangular or tubular and to angles, channels and Ts shall be subject to the requirements of annex B. The results of the assessment are applicable to all other grades of steel to that tested and as given in EN 10025 and EN 10113 as specified in 6.4.1 and with the limitations given therein. The assessment results from single or multilayer fire protection systems are applicable to single, double or
30
ENV 13381-4:2002 (E)
multilayers provided that, for any given thickness of fire protection, the number of layers is equal to or greater than that tested.
Table 1 - Standard test package Test specimens for evaluation of stickability 1), 2), 3) Number of specimens/type
Loading
Section Details
Am/V Profiled protection
Am/V Boxed protection
Thickness of Protection
1
BEAM
LOADED
E 400 (406 × 178 × 67)
153 (155)
116 (115)
MAXIMUM
1
BEAM
LOADED
IPE 400 (406 × 178 × 67)
153 (155)
116 (115)
MINIMUM
1
BEAM
UNLOADED
IPE 400 (406 × 178 × 67)
153 (155)
116 (115)
MAXIMUM
1
BEAM
UNLOADED
IPE 400 (406 × 178 × 67)
153 (155)
116 (115)
MINIMUM
1
COLUMN
LOADED OR UNLOADED
HEA 300 (305 × 305 × 97)
153 (145)
104 (100)
MAXIMUM
1)
The actual values of Am/V of the steel under test shall be used in the assessment. Dimensions given in brackets are approximate equivalent UK section sizes to the quoted European section references.
2)
The schedule in Table 1 shall be used in all cases, with the following exceptions: a) the ratio of maximum thickness/minimum thickness of the protection material is < 1,5 b) the material is only available in one thickness. In these cases only one loaded and one unloaded beam shall be tested at maximum thickness.
3)
An additional test on an unloaded 2 m tall column shall be carried out for reactive fire protection systems. Two tests on 3 m loaded columns may be carried out as an alternative or in addition to those on the loaded beams to provide data for a separate assessment of the fire protection system for 4 sided application to columns.
31
ENV 13381-4:2002 (E)
Table 2 - Differential Equation and Numerical Regression analysis methods Package of short steel column sections to be tested 1), 2), 3) Table 2.1 - Standard package of short steel column sections (10 specimens) SECTION SIZE
HEM 280 (305 × 305 × 198)
HEB 450 (356 ×
HEB 300 (305
HEA 400 (356
HEA 300
HEA 200
IPE 200
IPE 160
368 × 177)
× 305 × 118)
× 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 203 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
THICKNESS MINIMUM
X
X
X
X
1/4 MEDIUM
X
X
¾ MAXIMUM
X
X
1)
Table 1 also shall be applied to these tables.
2)
X indicates a mandatory part of the minimum standard package for which a test shall be made.
3)
The schedule in Table 2.1 shall be used in all cases, with the following exceptions:
X
X
a) the ratio of higher thickness/next lower thickness of the protection material is < 1,5 b) the material is not available in three or more thicknesses, in which case the short steel column sections shall be tested at two thicknesses or a single using the matrices shown in Tables 2.2 and 2.3. respectively.
Table 2.2 - Two thicknesses tested - Package of short steel column sections SECTION SIZE
HEM 280
HEB 450
HEB 300
HEA 400
HEA 300
HEA 200
IPE 200
IPE 160
(305 × 305 × 198)
(356 × 368 × 177)
(305 × 305 × 118)
(356 × 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 102 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
THICKNESS MINIMUM
X
X
X
X
X
MAXIMUM
32
X X
X
ENV 13381-4:2002 (E)
Table 2.3 - One thickness tested - Package of short steel column sections SECTION SIZE
HEM 280
HEB 450
HEB 300
HEA 400
HEA 300
HEA 200
IPE 200
IPE 160
(305 × 305 × 198)
(356 × 368 × 177)
(305 × 305 × 118)
(356 × 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 102 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
X
X
X
THICKNESS AVAILABLE
X
Table 3 - Differential Equation, Numerical Regression analysis and Graphical Presentation methods Package of short steel column sections to be tested 1), 2), 3), 4) Table 3.1 - Standard package of short steel column sections (18 specimens) SECTION SIZE
HEM 280
HEB 450
HEB 300
HEA 400
HEA 300
HEA 200
IPE 200
IPE 160
(305 × 305 × 198)
(356 × 368 × 177)
(305 × 305 × 118)
(356 × 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 102 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
THICKNESSM INIMUM
X
X
X
X*
1/4
X*
MEDIUM
X
3/4
X*
MAXIMUM 1) 2) 3) 4)
X
X*
X*
X*
X X*
X
X* X
X
X
Table 1 also shall be applied to these Tables. X indicates a mandatory part of the minimum standard package (10 specimens) from Table 2. X* indicates eight short steel column sections which may be tested for additional data points. The schedule in 3.1 of this table shall be used in all cases where an additional 8 data points are required, according to 13.5.2, 13.5.3 and 13.5.4, with the following exceptions: a) the ratio of higher thickness/ next lower thickness of the protection material is < 1,5, b) the material is not available in five thicknesses, in which case the short steel column sections shall be tested at three, two or a single thickness using the matrices shown in Tables 3.2, 3.3 and 3.4.
Table 3.2 - Three thicknesses tested - Package of short steel column sections SECTION SIZE
HEM 280
HEB 450
HEB 300
HEA 400
HEA 300
HEA 200
IPE 200
IPE 160
(305 × 305 × 198)
(356 × 368 × 177)
(305 × 305 × 118)
(356 × 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 102 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
THICKNESS MINIMUM
X
X
X
X
X*
X*
MEDIUM
X
X
X*
X*
X*
X*
MAXIMUM
X*
X
X
X
X*
X
33
ENV 13381-4:2002 (E)
Table 3.3 - Two thicknesses tested - Package of short steel column sections SECTION SIZE
HEM 280
HEB 450
HEB 300
HEA 400
HEA 300
HEA 200
IPE 200
IPE 160
(305 × 305 × 198)
(356 × 368 × 177)
(305 × 305 × 118)
(356 × 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 102 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
THICKNESS MINIMUM
X
X
X
X*
X*
MAXIMUM
X*
X
X
X
X*
X
X
Table 3.4 - One thickness tested - Package of short steel column sections SECTION SIZE
HEM 280
HEB 450
HEB 300
HEA 400
HEA 300
HEA 200
IPE 200
IPE 160
(305 × 305 × 198)
(356 × 368 × 177)
(305 × 305 × 118)
(356 × 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 102 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
THICKNESS AVAILABLE
X*
X
X
X
X
X*
34
ENV 13381-4:2002 (E)
Table 4 - Differential Equation, Numerical Regression analysis and Graphical Presentation methods Package of short steel column sections to be tested 1), 2), 3), 4), 5) Table 4.1 - Standard package of short steel column sections (26 specimens) SECTION SIZE
HEM 280
HEB 450
HEB 300
HEA 400
HEA 300
HEA 200
IPE 200
IPE 160
(305 × 305 × 198)
(356 × 368 × 177)
(305 × 305 × 118)
(356 × 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 102 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
MINIMUM
X
X
X
X*
1/4
X**
MEDIUM
X
3/4
X*
MAXIMUM 1) 2) 3) 4) 5)
X X*
X* X*
X** X
X**
X*
X** X*
X**
X
X** X X**(2 tests)
X* X
X
X**
Table 1 also shall be applied to these tables. For definition of X see note 2 Table 2. For definition of X* see note 3 Table 3 X** indicates eight short steel column sections which may be tested for additional data points. The schedule in 4.1 of this table shall be used in all cases where an additional 16 data points are required under 13.5.2, 13.5.3 and 13.5.4 with the following exceptions: a) the ratio of higher thickness/ next lower thickness of the protection material is < 1,5, b) the material is not available in five thicknesses, in which case the short steel column sections shall be tested at three, two or a single thickness using the matrices shown in Tables 4.2, 4.3 and 4.4 .
Table 4.2 - Three thicknesses tested - package of short steel column sections SECTION SIZE
HEM 280
HEB 450
HEB 300
HEA 400
HEA 300
HEA 200
IPE 200
IPE 160
(305 × 305 × 198)
(356 × 368 × 177)
(305 × 305 × 118)
(356 × 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 102 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
MINIMUM
X
X**
X
X**
X
X
X*
X*
MEDIUM
X
X**
X
X**
X*
X*
X*
X*
MAXIMUM
X*
X
X**
X**
X
X
X
X*
35
ENV 13381-4:2002 (E)
Table 4.3 - Two thicknesses tested - package of short steel column sections SECTION SIZE
HEM 280
HEB 450
HEB 300
HEA 400
HEA 300
HEA 200
IPE 200
IPE 160
(305 × 305 × 198)
(356 × 368 × 177)
(305 × 305 × 118)
(356 × 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 102 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
MINIMUM
X
X**
X
X**
X
X
X*
X*
MAXIMUM
X*
X
X**
X**
X
X
X
X*
Table 4.4 - One thickness tested - package of short steel column sections SECTION SIZE
HEM 280
HEB 450
HEB 300
HEA 400
HEA 300
HEA 200
IPE 200
IPE 160
(305 × 305 × 198)
(356 × 368 × 177)
(305 × 305 × 118)
(356 × 368 × 129)
(305 × 305 × 97)
(203 × 203 × 46)
(203 × 102 × 23)
(178 × 102 × 19)
Am/V BOXED
50
65
80
90
104
145
210
241
Am/V PROFILED
70
95
116
135
153
212
269
309
THICKNESS AVAILABLE
X*
X
X**
X**
X
X
X
X*
36
ENV 13381-4:2002 (E)
Table 5 - Example of tabulated date Fire resistance classification R-30
DESIGN (0C) TEMPERATURES Am/V 40
350
400
450
500
550
600
650
700
>700
THICKNESS OF FIRE PROTECTION MATERIAL TO MAINTAIN TEMPERATURE BELOW DESIGN TEMPERATURE
60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400
37
ENV 13381-4:2002 (E)
Table 6 - Permitted extensions
Assessment method
Differential method [variable ]
Differential method [fixed ]
Numerical equation method
Graphical method
Reference to annex
F
G
H
J
Section factor Am/V
- 20 % to + 50 %
- 20 % to + 50 %
-10 % to + 10 %
±0%
Fire protection material thickness
- 20 % to + 20 %
- 5 % to + 5 %
- 5 % to + 5 %
±0%
Design temperature
- 0 % to + 10 %
- 0 % to + 7½ %
- 0 % to + 5 %
±0%
38
ENV 13381-4:2002 (E)
Steel section
Profile protection
Box protection
I and H sections
4 sides
4 sides
Perimeter area
Perimeter area
2b + 2h + 2(b-tw) h = h(average) = (h1 + h2)/2
2b + 2h
= [4b + 2h - 2tw]
b = b(average) = (b1 + b2)/2 tf = tf(average) = (tf1 + tf2 + tf3 + tf4)/4
3 sides
3 sides
Cross sectional area tw (h - tf) + 2 (b × tf) Perimeter area
Perimeter area
b + 2h + 2(b-tw)
b + 2h
= [3b + 2h -2tw]
Section factor = Perimeter area/Cross sectional area
Figure 1 - Section factor - illustration of profiled and boxed
39
ENV 13381-4:2002 (E)
Figure 2 - Diagrammatic illustration of testing protocol (passive)
40
ENV 13381-4:2002 (E)
Figure 3 - Diagrammatic illustration of stickability testing protocol (reactive)
41
ENV 13381-4:2002 (E)
Figure 4 - Diagrammatic illustration of assessment protocol
42
ENV 13381-4:2002 (E)
Key 1 Load
5 Detail ‘B’ fixing of beam topping
2 Webb stiffener
6 Detail 'C’
3 Webb stiffener at load point
7 Ceramic fibre
4 Detail 'A' of load spacer
8 Compressible ceramic fibre insulation
9 Detail 'D' (not to scale) section along beam axis 10 Stud/plate/locking nut
Figure 5 - Loaded beam - construction of test section (reference 5.2.1, 6.2.1 and 7.1) 43
ENV 13381-4:2002 (E)
Side elevation
End elevation
End elevation
Key 1 2 3
Furnace cover Stud/plate/locking nut Thermocouples
4 5 6
Steel Thermocouples (opposite side of web) Insulation board
Figure 6 - Unloaded beam - construction of test section 44
ENV 13381-4:2002 (E)
Key 1 2 3 4
Hydraulic jack Loading frame Furnace Temperature measurement stations
5 6 X 0
Loaded column Opposite side of web Thermocouples Thickness measurement points
Figure 7 - Loaded column - example of general test arrangement plus thermocouple locations
45
ENV 13381-4:2002 (E)
Key 1 2 3 4
Stud/plate/locking nut Furnace cover Thermocouples (opposite side of web) Insulation board
5 6 X 0
Short column Tall column, construction as for short column Thermocouples Thickness measurement points
Figure 8 - Unloaded columns - thermal isolation, installation to cover slabs and thermocouple positions
46
ENV 13381-4:2002 (E)
Elevation
Plan
alternating sides of web) Key 1 Load 2 Webb stiffeners 3 Thickness measurement locations 4 Webb stiffener at load point
5 X 0
Load stiffener (plate) and support point Thermocouple locations Thickness measurement locations
Figure 9 - Loaded beam plus thermocouple positions
47
ENV 13381-4:2002 (E)
Key 1 2 3 4
Position of perimeter wall to furnace chamber Concrete topping Steel beam End of cavity sealed at furnace
5 6 7 8
Mineral fibre packing under beam only Steel roller Furnace wall Beam span
Figure 10 - Loaded beam - insulation of bearings
48
ENV 13381-4:2002 (E)
Key 1 Overall width of insulation 2 End of cavity sealed at furnace 3 Boxed protection
4 5
Furnace cover Profiled protection
Figure 11 - Loaded beam - application of insulation board 49
ENV 13381-4:2002 (E)
Key 1 2 3 4
Short column position Unloaded short beam position Loaded beam Short column
Figure 12 - Typical test specimen installation pattern
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ENV 13381-4:2002 (E)
Dimensions in millimetres
Key 1 Thermocouple
Figure 13 - Location of furnace control thermocouples for beams
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ENV 13381-4:2002 (E)
Key A Time to reach D B Section factor Figure 14 - Plot of time to reach D (design temperature) vs. section factor
Key A D B Section factor Figure 15 - Plot of D vs. section factor
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ENV 13381-4:2002 (E)
Annex A (normative) Test method to the smouldering fire or slow heating curve A.1
Introduction Fire protection products activated by the heat flux of the fire may be required to be subjected to a test to a smouldering curve (slow heating curve as defined in EN 1363-2), with a rate of temperature increase less than that of the standard temperature/time curve. NOTE See Council Directive 89/106/EEC, ID No 2: Safety in case of fire, 3.2.4 and 4.3.1.3.4 (b). This exposure, applicable to reactive fire protection materials, is used only in special circumstances, where it might be expected that the performance of the product when exposed to a smouldering fire might be substantially less than when it is exposed to the standard temperature/time curve, and where such a test is specified in the national building regulations of the Member State of destination. It is not intended to be mandatory for all fire protection materials applied to structural steel members.
A.2
Test equipment The furnace and test equipment shall be designed to permit the test specimens to be exposed to heating as specified within A.5. The smouldering curve (slow heating curve) shall be as specified in EN 1363-2, where it provides a heating regime wherein during the period t = 0 minutes to 20 minutes the furnace temperature (T) follows the relationship: T = 154 4√t + 20 After t = 20 minutes and for the remainder of the test, the furnace temperature (T) follows the temperature/time relationship: T = 345 log10 [8(t-20) + 1] + 21. This heating protocol is shown graphically in Figure A.1.
A.3
Test specimens The four short steel columns and applied fire protection material shall be as specified in 6.2.5, 6.3.5, 6.3.6, 6.4 and 6.5. There shall be used for this test: one short column of type IPE 200 [Am/V profiled = 269] with maximum thickness of fire protection, one short column of type HEA 200 [Am/V profiled = 212] with minimum thickness of fire protection, one short column of type HEB 450 [Am/V profiled = 95] with maximum thickness of fire protection, one short column of type HEM 280 [Am/V profiled = 70] with minimum thickness of fire protection. All test specimens shall be verified according to 6.6 of this test method.
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ENV 13381-4:2002 (E)
A.4
Termination of test Terminate the test after 40 minutes or if it becomes unsafe to continue according to EN 1363-1.
A.5
Evaluation of the results The characteristic temperature test data obtained for each of the four defined short columns when subjected to both the standard temperature/time curve (according to the principal test) and the smouldering curve (this test) shall be compared each with the other. The results from all thermocouples in each comparable location shall be examined and recorded by tabulation. The results from each comparable location shall be presented graphically, in a manner similar to that given in Figure A.1, and the performance of the fire protection material to the two fire sources compared and recorded. The values of 1 and 2 shall be measured and recorded for all comparable locations. The results of tests carried out according to the standard temperature/time curve for the particular reactive fire protection material under test shall only be valid and applicable if 1 > 2 in each and every comparable location.
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ENV 13381-4:2002 (E)
Key A B 1 2 3 4
Temperature °C Time (min) Standard temperature/time curve Smouldering (slow heating) curve Test element temperature to standard temperature/time curve Test element temperature to smouldering (slow heating) curve
Figure A.1 - Comparison of performance to the standard and smouldering fire curves
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ENV 13381-4:2002 (E)
Annex B (normative) The applicability of the results of the assessment to sections other than ‘I’ or ‘H’ section B.1
STRUCTURAL HOLLOW SECTIONS
B.1.1 Passive fire protection systems B.1.1.1 General Test data exist on structural hollow sections (SHS) as compression and flexural members which together with recent research have indicated comparability between SHS sections and ‘I’ or ‘H’ sections in terms of the fire protection thickness related to the section factor Ai/V1. The test information has been analyzed for rectangular, square and circular sections to establish comparability with respect to fire protection thickness, section factor and fire resistance performance and the approaches in B.1.1.2, B.1.1.3 and B.1.1.4 are recommended for both three and four sided protection to both beams and columns. B.1.1.2 Boxed systems Where thicknesses of the fire protection material have been assessed from ‘I’ or ‘H’ sections with boxed protection, no change in thickness is required, i.e. the thickness for a SHS of a given Ap/V value is equal to that for the ‘I’ or ‘H’ section of the same ‘box’ Ap/V value. B.1.1.3 Profiled systems Where thicknesses of the fire protection material have been assessed from ‘I’ or ‘H’ sections with profiled protection, a correction to the thickness is required based on the Ap/V value of the section as follows: a) establish the Ap/V value of the Structural Hollow Section, b) determine the thickness of the fire protection material based on the ‘I’ or ‘H’ section data. This is the thickness, dp, in mm. c) increase the thickness as follows:
A /V Modified thickness = d p 1 + p 1000 i) for Ap/V values up to 250 m-1, ii) for Ap/V values higher than 250 m-1. Modified thickness = 1,25 dp B.1.1.4 Limitation The maximum thickness that can be applied to structural hollow sections shall not exceed the maximum assessed for ‘I’ or ‘H’ sections. The rules outlined in this annex may be used providing that the different section shape does not require new fixing techniques and does not affect the physical performance of the fire protection system. 1 Fire Protection of Structural Hollow Sections - Transposition of Spray Protection from ‘I’ Section Test Data. British Steel Corporation [CE854/0502 author M. Edwards, BSC Tubes Division].
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B.1.2 Reactive fire protection systems B.1.2.1 General The behaviour of reactive fire protection systems on 'I' and 'H' section members has been demonstrated as being much more reliable than on structural members which have no re-entrant detail, e.g. square or circular section members and angles. It is not considered, therefore, that the data obtained on 'I' and 'H' members can be directly related to other members without further evidence of stickability. The following procedure is a simple approach to correcting the assessment data in such a way that it may be extended to square hollow or circular hollow tube sections. It is possible that a more comprehensive appraisal may be made by using an analogous approach whereby the testing programme may be conducted entirely with square and/or hollow sections and the results of the assessment limited accordingly. B.1.2.2 Tall steel column section test To provide the necessary data to adapt the results of the assessment from 'I' and 'H' sections to square hollow sections, a test shall be made of the material at both maximum and minimum thickness of the fire protection system applied to a square hollow section of nominal size 100 mm × 100 mm × 7,1 mm wall thickness (Ap/V = 147 m-1). To provide the necessary data to adapt the results of the assessment from 'I' and 'H' sections to circular hollow sections, a test shall be made of the material at both maximum and minimum thickness of the fire protection system applied to a circular hollow section of nominal size 76,1 mm diameter × 5 mm wall thickness (Ap/V = 214 m-1). B.1.2.3 Correction of temperature data for thickness and stickability according to section shape The temperature data from the square hollow section columns shall be used to correct the temperature data obtained from the short steel columns for use with square hollow section members. Similarly, the temperature data from the circular hollow section columns shall be used to correct the temperature data obtained from the short steel columns for use with circular hollow section members. Corrections for each section shape for discrepancy in fire protection thickness and stickability shall be determined as given in 13.2 and 13.3 for both maximum and minimum thickness of the material. For the square hollow section this shall be based on comparison with the HEA 300 short steel columns. For the circular hollow section this shall be based on comparison with the HEA 200 short steel column sections. B.1.2.4 Limitation The maximum value of any correction factor derived as indicated in B.1.2.3, shall not be greater than 1,5. If the value of the derived correction factor is greater than 1,5 then such a correction of the ‘I’ and ‘H’ section data is inappropriate and a new testing programme shall be conducted involving square and/or circular hollow sections. The maximum thickness that can be applied to structural hollow sections shall not exceed the maximum assessed for ‘I’ and ‘H’ sections, unless substantiated by fire test data.
B.2
ANGLES, CHANNELS AND ‘T’ SECTIONS Angles, ‘T’ sections and channels have high Ap/V values and would theoretically require excessive thicknesses of fire protection material in order to achieve the specified fire protection. In this case, ENV 1993-1-2 shall be consulted to determine the needs for any such members to be fire protected.
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Annex C (normative) Measurement of properties of fire protection materials C.1
Introduction Determination of the thickness, density and moisture content of the fire protection materials and other materials used in fire resistance tests is important to the accurate prediction of required fire protection thicknesses from the test result. The methods used to establish these properties shall, therefore, be consistent and this annex gives guidance on appropriate procedures to be used. Any special test samples used to determine thickness, density and moisture content shall be conditioned with the actual fire test specimen under the conditions described in clause 8. Any specific product standard existing for the measurement of such properties shall be followed. The procedures given in EN 1363-1 shall be followed together with the following.
C.2
Thickness of fire protection materials
C.2.1 For board or panel passive fire protection materials, the nominal thickness of each material shall be measured using suitable gauges or callipers. The measurement shall be carried out either on the actual materials during assembly of the test specimen or on a representative special test sample, the minimum linear dimensions of which shall be 300 mm × 300 mm. At least nine measurements shall be made including measurements around the perimeter and over the surface of the material. The design thickness used in the assessment shall be as described in 6.5.2. C.2.2 For sprayed passive fire protection materials and coatings of thickness greater than 5 mm, the thickness shall be measured using a 1 mm diameter probe or drill, which shall be inserted into the material at each measurement position until the tip of the probe or drill touches the surface of the building element. The probe or drill shall carry a circular steel plate of diameter 50 mm upon it, for accurate determination of the surface level. The number and location of thickness measurement points shall be as given C.2.4. The design thickness used in the assessment shall be as defined in 6.5.2. For sprayed fire protection materials, of thickness very much greater than 5 mm, (i.e. where the mean thickness of the fire protection is greater than 15 % of the height of the test member) the mean thickness shall be given by:
d av =- A p + _
where and where
( A2p + 16 V p ) 8
Ap is the area of fire protection material per unit length Vp is the volume of area of fire protection material per unit length
C.2.3 For sprayed fire protection materials and coatings of thickness less than 5 mm, including reactive fire protection coating materials, applied to the surface of steel beam and column test members, the dry film thickness shall be determined directly upon the test member, once the coating is fully dried. 58
ENV 13381-4:2002 (E)
The thickness shall be measured using an instrument employing either the electro-magnetic induction principle or the eddy current principle with a probe contact diameter of at least 2,5 mm. Reactive fire protection materials applied as coatings typically range from 0,25 mm to 4 mm thickness and the choice of instrument shall be appropriate to the thickness of the coating used. The number and location of thickness measurement points shall be as described in C.2.4. The design thickness used in the assessment shall be as described in 6.5.2. C.2.4 Number and location of thickness measurement points for sprayed fire protection materials and coatings For sprayed passive and reactive fire protection materials applied to test members, the number and location of thickness measurement points (which shall be regarded as the minimum required) shall be: Loaded beams: Measurements at eight positions on the exposed surfaces of the beam (web and flanges see Figure 9) at a total of 13 locations (104 measurements in total) in the proximity of: - those 5 temperature measurement stations at which temperature measurements are made on the surface of the test beam, (see 9.3.2 and Figure 9, positions 1-5); - those four positions at which temperature measurements are made on the upper surface of the bottom flange of the beam, halfway between each temperature measurement station, (see 9.3.2 and Figure 9); - those two outermost positions at which temperature measurements are made on the upper surface of the bottom flange of the beam, halfway between each outermost temperature measurement station and the final exposed end of the beam, (see 9.3.2 and Figure 9); - those two positions halfway between the outermost temperature measurement stations and the outermost points at which temperature measurements are made on the upper surface of the bottom flange of the beam, (see 9.3.2 and Figure 9). Unloaded beams: Measurements at eight positions on the exposed surfaces of the beam (web and flanges see Figure 9) at a total of two locations (16 measurements in total) in the proximity of: - those two temperature measurement stations (between 50 mm to 100 mm away from) at which temperature measurements are made on the surface of the test beam, (see 9.3.3 and Figure 6). Loaded columns: Measurements at 10 positions on the exposed surfaces of the column (web and flanges see Figure 7) at a total of 11 locations (110 measurements in total) in the proximity of: - those six temperature measurement stations (between 50 mm to 100 mm away from) at which temperature measurements are made on the surface of the test column, (see 9.3.4 and Figure 7); - those five positions halfway between each temperature measurement station, (see 9.3.4 and Figure 7). Unloaded tall columns: Measurements at 10 positions on the exposed surfaces of the column (web and flanges see Figure 8) at a total of six locations (60 measurements in total) in the proximity of: - those six temperature measurement stations (between 50 mm to 100 mm away from) at which temperature measurements are made on the surface of the test column, (see 9.3.5 and Figure 8). Unloaded short columns: Measurements at 10 positions on the exposed surfaces of the column (web and flanges see Figure 8) at a total of two locations (20 measurements in total) in the proximity of: - those two temperature measurement stations (between 50 mm to 100 mm away from) at which temperature measurements are made on the surface of the test column, (see 9.3.6 and Figure 8).
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C.3
Density of applied fire protection materials
C.3.1 The density of each fire protection material shall be determined from measurements of mass and dimensions using the following: For board or panel passive fire protection materials, the density can be obtained from values of mass, mean thickness (from nine measurements) and area measured either on the actual materials during assembly or on a representative special test sample, the minimum linear dimensions of which shall be 300 mm × 300 mm. The mass of the board shall be obtained using a balance having an accuracy equivalent to 0,1 % of the total mass of the sample being weighed or 0,1 g (the sample size shall be sufficient such that the minimum sample mass is 100 g) whichever is the greater. The density of fibrous or similar compressible fire protection material shall be related to the nominal thickness. C.3.2 For spray applied fire protection materials, including where appropriate thick coatings, the density of the material shall be determined from samples sprayed, from beneath, into metal trays, horizontally orientated, at the same time as the fire protection system is applied to the steel test specimens. These trays shall be of size 300 mm × 300 mm and made from 1 mm thick steel plate. The depth of the trays shall be the same as the design thickness of the fire protection material. For each thickness of material two such trays shall be prepared with the material applied to the same thickness as that applied to the steel. One of these trays is dried to provide a reference for dry density and moisture content. The second tray shall be used to determine the density at the time of test. The thickness of the specimen within the trays shall be determined at nine positions over the surface of the trays according to: - one at the centre (one total); - two along each centre to corner axis, equidistant from each other, the centre and the corner (eight in total). The mass of the fire protection within the tray shall be obtained using a balance having an accuracy equivalent to 0,1 % of the total mass of the sample being weighed or 0,1 g (the sample size shall be sufficient such that the minimum sample mass is 100 g) whichever is the greater. It is inappropriate to measure the density of thin coatings and intumescent paints. C.3.3 The design density used in the assessment shall in all cases be as described in 6.5.2
C.4
Moisture content of applied fire protection materials
C.4.1 The samples and materials used to measure moisture content shall be stored together with and under the same conditions as the test specimens. The measurement of final moisture content shall be made on the day that fire testing takes place. C.4.2 For board or panel passive fire protection materials, special test samples shall be taken measuring minimum 300 mm × 300 mm and of each thickness of the material used. They shall be weighed and dried in a ventilated oven, using the temperatures and techniques specified in EN 1363-1. The moisture content of the specimen shall be calculated as a percentage of its moisture equilibrium weight. C.4.3 For spray applied passive fire protection materials, the moisture content of the material shall be determined from oven drying of one of the sample trays referred to in C.3.2, for each thickness tested. They shall be weighed and dried in a ventilated oven, using the temperatures and techniques specified in EN 1363-1. The moisture content of the specimen shall be calculated as a percentage of its moisture equilibrium weight.
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Annex D (normative) Fixing of thermocouples to steel work and routing of cables D.1
Introduction The accurate measurement of steel temperatures is fundamental to the assessment methodology. The type of thermocouple and the method of attachment and routing, protection and connection to suitable compensating cables or extensions shall therefore, be considered carefully. This annex offers guidance on suitable procedures.
D.2
Types of thermocouples Several different kinds of thermocouple wire are suitable, including types ‘T’, ‘N’, ‘K’ and ‘J’ as specified in IEC 60584-1. The diameter of each wire shall be in excess of 0,5 mm to ensure that mechanical problems do not result from possible strains on the wire introduced during the test. However, where mineral-insulated stainless steel sheathed thermocouples are used, the overall diameter over the sheath shall be at least 1,5 mm. Suitable thermocouples shall be provided with insulation between the two wires, and between each wire and any external conducting material such that there shall be no failure likely during the test. For reactive fire protection materials stainless steel sheathed thermocouples with an isolated hot junction shall be used.
D.3
Fixing of thermocouples The hot junction of the thermocouple shall be attached to the steelwork by welding, peening or other methods that do not affect the response or accuracy of the thermocouple. Mechanical attachment using screws or bolts shall not be permitted. Irrespective of the fixing methodology, it is essential that the two thermocouple wires do not make contact beyond the hot junction which shall be in or at the steel surface; a thermocouple hot junction shall always be made at the position which creates the shortest loop between it and the cold junction. One recommended method of fixing is to separately secure each wire to the steelwork approximately 3 mm to 6 mm apart such that resulting temperature measured will be that of the steelwork between the two wire contacts. For a distance of approximately 50 mm from the hot junction, the thermocouple wires shall follow the anticipated isotherm through the hot junction position and shall be fixed to ensure that it remains at that position.
D.4
Routing of thermocouple wires Every attempt shall be made, whenever possible, to ensure that the wire from the hot junction follows a route to the cold junction which does not expose it to a temperature in excess of the hot junction temperature. The wires shall be routed behind the fire protection material and out of the furnace without passing through the furnace environment. For thin film coatings it may be necessary to protect the thermocouple wires by use of a channel or conduit prior to the application of the fire protection material. It shall be remembered that the claimed temperature performance of the thermocouple insulation material will relate to the thermocouple being in an environment where the wires are not subjected to movement or other strain. 61
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It is possible that thermocouple wires will need to be supported to ensure that failure of the insulation material does not occur.
D.5
Connection of thermocouples No connections shall be made between the thermocouple wire and any extension or compensating cable within any region of high temperature. Compensating leads shall always be of a type appropriate to the thermocouple wire.
D.6
Thermocouple failures Thermocouple failures are not always easily identifiable. Failure may be caused by a break within the wires or by failure of the electrical insulation between wires, thereby short circuiting the hot junction. Obvious signs of failure, however, are: - a sudden decrease of indicated temperature from that previously recorded; - a sudden increase in indicated temperature to a value representing the maximum range of the recording device; - a ‘floating or wandering’ indicated temperature inconsistent with anticipated values. A common sign of electrical insulation failure may be the observation of an indicated temperature value inconsistent with that of the furnace.
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Annex E (normative) Correction for discrepancies in thickness between loaded and equivalent unloaded sections Example of calculation:
Loaded beam
:
mean thickness (dLB)
-
60 mm (0,06 m)
Unloaded beam
:
mean thickness (dUB)
-
61,1 mm (0,061 m)
For, say,
UB =
600 °C
LB =
630 °C
a)Correct temperature of reference section (as if thickness dUB were 60 mm):
θ c(UB) = 140 + ( θ UB - 140) × [
θ c(UB) = 140 + (600 - 140) × [
d UB 0,77 ] d LB
61,1 0,77 ] 60
θ c(UB) = 606,48°C
b) Determine correction factor for short beam
θ LB θ c(UB) 630 ∴ k θ 606,48 = 606.48 = 1,04 k θ c(UB) =
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ENV 13381-4:2002 (E)
Annex F (normative) Assessment methodology: Differential equation analysis (variable approach) F.1 Input data Input data shall be as specified in clause 13.
F.2 Basic Equation The basic differential equation is:
λ p,t / d p A p 1 ∆ θ a,t = × ×( ) × ( θ t - θ a,t ) ∆t V 1 + φ/3 ca ρ a
φ/10 - [ ( e - 1) ∆ θ t
]
(F1)
But ∆ θ a,t ≥ 0
where φ =
cp ρ p Ap × dp × V ca ρ a
and where θ a,t = temperature of the steel at time t (i.e. θ m(SC) or θ SC )
and where ∆ t = ≤ 0,5 minutes
If the calculated is larger than 0,5 minutes, then 0,5 minutes should be chosen. To satisfy the numerical stability criteria the time increment shall be chosen to be not more than 80 % of the critical time increment and be given by:
∆t = 0,8 ×
V ca ρ a × × (1 + φ/3) λ p,t / d p A p
Cp, the measured temperature independent specific heat of the fire protection material shall be given by the supplier. If this value is not available then a value of 1 000 kJ/kg °C shall be used.
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F.3 Methodology The following stepwise methodology shall be performed: -
use of output data from test results (steps 1 to 4); determination of the mean values of the thermal conductivity and moisture plateau (steps 5 to 7); verification of criteria of acceptability (steps 8 to 10); modification of thermal conductivity (steps 11 and 12); presentation of results (step 13); reporting of the results (step 14).
Steps 1 to 4: Use of output data from test results step 1
For each short steel column section smooth the variation of measured steel temperature by using a method such as cubic splines or moving means. Also for each short steel column evaluate the moisture plateau length Dp, as shown in Figure F.1 and according to the instructions below. The moisture plateau length, Dp, is the distance (in minutes) between the intercept of the straight line (d1) and that of the similar straight line (d2) with the line t = 100 °C, Where: d1 is the straight line drawn through the following temperature/time points: [60 °C / t60°C] and [80 °C / t80°C]. d2 is the straight line drawn through the following temperature/time points: [115 °C / t115°C] and [200 °C / t200C].
step 2
For each short steel column determine p as a function of time (p vs. t) [using the inverse function equation (F2) of equation (F1)] to give the effective thermal conductivity, p(t).
V 1 φ 10 × ca ρ a × ( 1 + φ/3 ) × λ p,t (t) = d p × × [ ∆ θ a,t + ( e - 1 ) ∆ θ t Asubp ( ) t ∆ θ t θ a,t
]
where ∆ t ≤ 0,5 minutes [Equation F2] step 3
For each short steel column and for each time interval determine the mean fire protection material temperature, p , from:
θ p= step 4
( θ t +θ a ) 2
Transform the (p vs. t) values to (p vs. p)values.
Steps 5 to 7: Determination of mean values of the thermal conductivity and moisture plateau step 5
Calculate the arithmetical mean value of p for each short steel column section (pm) over each range belonging to (p, p + 50 °C) for p equal to 0 °C to 1 000 °C at 50 °C intervals.
step 6
Calculate the arithmetical mean value of pm for all the short steel columns sections (ave) over each range belonging to (p, p + 50 °C) for p equal to 250 °C to 1 000 °C at 50 °C intervals.
step 7
Determine a smooth curve of moisture plateau length (Dp) versus fire protection material thickness (dp) as follows 65
ENV 13381-4:2002 (E)
and as in Figure F.2: Dp = C × dp3 n
∑d C=
3 p
× Dp
i=1
n
∑d
6 p
i=1
Where n is the number of specimens and
Dp is the moisture plateau length for each short steel column calculated according to step 1 (mins) dp is the thickness of fire protection material on each short steel column (mm).
Steps 8 to 10: Verification of criteria of acceptability step 8
For each short steel section, recalculate the steel temperature versus time using equation (F1) and = char. The value of shall be appropriate to the range of temperature of the steel section at each step of the calculation. For steel temperatures lower than 300 °C the value of shall be that from the range 250 °C to 300 °C. For steel temperatures greater than 1 000 °C the value of shall be that from the range 1 000 °C –to 1 050 °C. For the first stage of the calculation = char (see step 11). The moisture plateau length may be introduced as follows and as shown in Figure F.3. - Calculate a using equation (F1) until a = 100 °C obtained to give time t1 - Calculate Dp as a function of the thickness of fire protection material dp - Add this time to t1 For time after (t1 + Dp) calculate a with equation (F1).
step 9
Calculate the time (up to the maximum time tmax) to reach the design steel temperature over the range of 350 °C up to the maximum steel temperature (max) at 50 °C intervals. [tmax and max are determined according to the main part of this test method].
step 10 Compare this time with the measured time to reach the same temperature on the same equivalent short column section. If the three criteria given in 13.6.1 are satisfied the calculation is finished. Proceed to step 13. If not proceed to step 11. Steps 11 and 12: Modification of thermal conductivity step 11 If one or more of the three criteria of acceptability are not satisfied determine the characteristic value of (char) over the range of p from 250 °C to 1 050 °C at 50 °C intervals as follows:
λ char(p) = λ ave(p) + K λ sp where ave is calculated according to step 6. and sp is the standard deviation of the pm value over the range of p of 250 °C to 1 050 °C at 50 °C intervals. 66
ENV 13381-4:2002 (E)
and K is the modification coefficient. This value is chosen to be as small as possible to just satisfy the three criteria of 13.6.1. step 12 Return to steps 8, 9 and 10 and repeat the calculation until the criteria of 13.6.1 are satisfied. Step 13: Presentation of the results step 13 Draw the curves and make the tables as specified in this part of ENV 13381. Step 14: Reporting of the results step 14 Report the results and their assessment according to clause 14. NOTE An alternative assessment methodology to be considered for the differential equation method, using a constant approach, is presented in annex G.
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Key A Temperature °C B Time (min) Figure F.1 - Evaluation of length of moisture plateau
Figure F.2 - Evaluation of the moisture plateau vs. fire protection material thickness 68
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Key A Temperature °C B Time (min) Figure F.3 - Introduction of moisture plateau
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Annex G (normative) Assessment methodology: Differential equation analysis (constant approach) G.1 Input data Input data shall be as specified in clause 13.
G.2 Basic Equation The basic differential equation is
λ p / d p Ap 1 ∆ θ a,t = × ×( ) × ( θ t - θ a ) ∆t 1 + φ/3 ca ρ a V
φ/10 - [ ( e - 1) ∆ θ t
]
(G1)
But ∆ θ a,t ≥ 0
where φ =
cp ρ p Ap × dp × V ca ρ a
and where θ a,t is the temperature of the steel at time t (i.e. θ m(SC) or θ SC )
and where ∆ t = ≤ 0,5 minutes If the calculated is larger than 0,5 minutes, then 0,5 minutes should be chosen. To satisfy the numerical stability criteria the time increment shall be chosen to be not more than 80 % of the critical time increment and be given by:
∆t = 0,8 ×
ca ρ a V × × (1 + φ/3) λ p / d p Ap
Cp, the measured temperature independent specific heat of the fire protection material shall be given by the supplier. If this value is not available then a value of 1 000 kJ/kg °C shall be used.
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G.3 Methodology The following stepwise methodology shall be performed: -
use of output data from test results (steps 1 to 3); verification of criteria of acceptability (step 4); modification of C0 (step 5); presentation of results (step 6); reporting of the results (step 7).
Steps 1 to 3: Use of output data from test results step 1
For each short steel column tested and for design steel temperatures d from 350 °C to the maximum value for which the analysis is requested, in 50 °C intervals, determine on the basis of equation (G1) the effective thermal conductivity, p (d ; dp), such that the time at which the calculated steel temperature a,t reaches the design value d, equals the measured time to reach that steel temperature.
step 2
For each combination of design steel temperature and fire protection material thickness take the arithmetical mean p (d ; dp) of all values of p (d ; dp) involved, (remark : this means averaging over the section values).
step 3
Fit the values of p (d ; dp) to the following bi-linear model using the method of least squares (and the equation G2):
λ = C0 + ( C1 × θ d ) + ( C 2 × d p )
(G2)
NOTE The length of the moisture plateau is implicitly and automatically taken into account within this methodology and therefore into the results of the assessment.
Step 4: Verification of criteria of acceptability step 4
For each short steel column tested and for design steel temperatures from 350 °C to the maximum temperature value for which the analysis is requested, in 50 °C intervals, calculate the time to reach that temperature using equation G1 and using for p the value calculated from equation G2. Determine whether the results meet the acceptability criteria of paragraph 13.6.1.
Step 5: Modification of C0 step 5
Repeat step 4 with modified C0 until the acceptability criteria of 13.6.1 are met. The outcome of the analysis is the combination of regression coefficients C0 (modified if appropriate), C1 and C2.
Step 6: Presentation of the results step 6
Draw the curves and make the tables as specified in this part of ENV 13381.
Step 7: Reporting of the results step 7
Report the results and their assessment according to clause 14 of this test method.
NOTE An alternative assessment methodology to be considered for the differential equation method, using a variable approach, is presented in annex F.
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Annex H (normative) Assessment methodology: Numerical regression analysis H.1 Data The input data used for this methodology are the thicknesses of the fire protection system (dp) on the short column sections and the temperature data corrected for stickability, m(SC) , if necessary, otherwise SC (see 13.2.4).
H.2 Basic Equation The multiple linear numerical regression analysis is conducted using the following equation:
dp Ai /V 1 θ θ + a 3 θ SC + a 4 d p θ SC + a 5 d p SC + a6 SC + a7 Ai /V Ai /V Ai /V t = a o + a1 d p + a 2
H.3 Methodology The following stepwise methodology shall be performed: -
use of output data from test results (steps 1 to 5), reporting of the results (step 6).
Steps 1 to 5: Use of output data from test results step 1
Determine the constants a0, a1, a2, a3, a4, a5, a6 and a7 by solving the regression equation using all the test data for design temperatures from 350 °C to the maximum temperature for which the analysis is requested, in 50 °C intervals.
step 2
Using the constants, calculate the time required to reach each design temperature for various thicknesses of the fire protection system and various section factors.
step 3
Compare the predicted times to reach each design temperature with the measured times and determine whether the results meet the criteria of 13.6.1.
step 4
If necessary, determine for each of the three acceptance criteria a simple linear modification factor of value (≤ 1,0) which, when applied to all the regression constants, causes the predicted times to just meet the acceptance criteria.
step 5
Use the modified regression coefficients to determine the information to be presented in the report of the assessment as required in 13.4 and clause 14.
NOTE The length of the moisture plateau is implicitly and automatically taken into account within this methodology and therefore into the results of the assessment.
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ENV 13381-4:2002 (E)
Step 6: Reporting of the results step 6
Report the results and their assessment according to clause 14.
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ENV 13381-4:2002 (E)
Annex J (normative) Assessment methodology: Graphical presentation J.1
Data The input data used for this methodology are the thicknesses of the fire protection material on the short column sections and the temperature data corrected for stickability, m(SC) , if necessary, otherwise SC (see 13.2.4).
J.2
Methodology The following stepwise methodology, illustrated in Figure J.1, shall be performed..
Steps 1 to 4: Use of output data from test results step 1
If the actual measured thickness of the fire protection is different from its nominal thickness, for each design temperature plot, for constant section factors, the time to reach that design temperature against the thickness of the fire protection material applied to the short column.
step 2
From the test data or from the graphs plotted in step 1, determine and graphically present, at each design temperature and for each thickness of fire protection material, the variation in the time to reach that design temperature as a function of the section factor.
step 3
In preparing the graphical presentation required under step 2, the following rules shall be applied:
step 4
a)
ensure that as the thickness of the fire protection material increases, the time to reach a given design temperature also increases;
b)
ensure that as section factor increases, the time to reach a given design temperature is decreasing;
c)
points which do not meet requirement b) shall be omitted;
d)
connect individual points on the graph with straight lines only, with no curve fitting.
From the graphs plotted in step 2, determine for each period of fire resistance, and for each thickness of fire protection material, the temperature of the short columns at the end of the fire resistance period as a function of section factor.
NOTE The length of the moisture plateau is implicitly and automatically taken into account within this methodology and therefore into the results of the assessment. Step 5: Restriction of Field of Application step 5
If any of the rules in step 3 are not satisfied, the field of application of the assessment shall be limited to the scope of section factor and time period for which they are satisfied.
Step 6: Tabulation of results step 6
Determine by interpolation from the graphs plotted, the time required to reach each design temperature for the various thicknesses of fire protection system and the various section factors. Tabulate these results, (an example of such tabulation is shown in Table 5).
Step 7: Reporting of the results step 7 74
Report the results and their assessment according to clause 14.
ENV 13381-4:2002 (E)
Figure J.1 - Assessment methodology
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ENV 13381-4:2002 (E)
Bibliography ENV 13381-1
Test methods for determining the contribution to the fire resistance of structural members - Part 1: Horizontal protective membranes.
ENV 13381-2
Test methods for determining the contribution to the fire resistance of structural members - Part 2: Vertical protective membranes.
IEC 60584-1
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Thermocouples - Part 1: Reference tables.
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