YELLOW BOOK. Fire protection for structural steel in buildings 4 th Edition

Transcription

1 YELLOW BOOK Fire protection for structural steel in buildings 4 th Edition Association for Specialist Fire Protection Kingsley House, Ganders Business Park, Kingsley, Bordon, Hampshire GU35 9LU, United Kingdom t:

2 ASFP YELLOW BOOK Amendments to Vol 1: Section 1-9 (Amendments to Vol 2: Section 10 included in the front of each product section) DATE SECTION AMENDMENT SUMMARY SOURCE 13/07/07 ALL Book divided into two volumes. Vol 1: Sections 1-8 & 10 and Vol 2: BP Section 9 Product Data Sheets 06/08/07 1 Table 3: BP 610x305x149 area of section changed to /08/07 1 Table 6: BP Parallel flange channels, 3-sided profile drawing corrected 06/08/07 1 Table 9: BP 3-sided profile and box drawings exchanged 06/08/07 1 Table 10: Structural tees, 3-sided profile drawing corrected 305 x 152 x 58.9, 4-sided profile section factor changed to 125 BP 06/08/07 1 Table 13: 60 x 60 x 4mm 4-sided section factor changed to /08/07 1 Table 14: 120 x 80 x 4mm 3-sided (2nd col) section factor changed to /11/07 1 Repagination of pages BP 17/12/ (c) change 150mm to 160mm BP 17/12/08 6 Include amended tables 25, 26 and 27 BP 14/01/09 5 & 7 Correct equation 3-7 within publication BP 09/04/09 5 Changes to wording of Section item 8 BP 09/06/09 Intro Fire and Legal Liability & updated disclaimer added BP 30/07/09 4 Amendments to section item 7 BP 30/07/09 1 New section BP 30/07/09 6 New section 6.4 BP 05/08/09 Intro Typographical amendment: para 4 line 1 BP 07/10/09 Front Addition of CPD logo JF BP BP Note 1: Amendments may only be inserted by ASFP Secretariat with approval of the ASFP Technical Officer. Association for Specialist Fire Protection 2 Fire protection for structural steel in buildings INTRODUCTION 4 th Edition revised 7 Oct 09

3 The Association was formed in 1976, and currently represents UK contractors and manufacturers of specialist passive fire protection products, with associate members representing regulatory, certification, testing and consulting bodies. It seeks to increase awareness and understanding of the nature of fire and the various forms, functions and benefits provided by passive fire protection. It is willing to make its specialist knowledge on all aspects of fire protection and can assist specifiers and main contractors in identifying products suitable for specific requirements, both in the UK and related overseas markets. The Association encourages experimental work related to passive fire protection and promotes consideration and discussion of all issues affecting the fire protection of structural steel and buildings. Association for Specialist Fire Protection (ASFP) Kingsley House, Ganders Business Park, Kingsley, Bordon, Hampshire GU35 9LU, United Kingdom T: The Steel Construction Institute (SCI) develops and promotes the effective use of steel in construction. It is an independent, membership based organisation. SCI s research and development activities cover multi storey structures, industrial buildings, bridges, civil engineering and offshore engineering. Activities encompass guidance on structural design in carbon and stainless steels, dynamic performance, fire engineering, sustainable construction, architectural design, building physics (acoustic and thermal performance), value engineering, and information technology. Membership is open to all organisations and individuals that are concerned with the use of steel in construction. Members have access to specialist advisory service, free issue of every new SCI publication and free access to Steelbiz, an online technical information system ( The Steel Construction Institute, Silwood Park, Ascot, Berkshire, SL5 7QN t: +44 (0) The Fire Test Study Group (UK) (FTSG) is a forum for technical discussions and liaisons between consulting fire test laboratories involved in producing test and assessment information for the purposes of building control. The member laboratories are all UKAS Accredited for testing. The primary objective of the group is to ensure common technical interpretations of the fire test standards and a common approach to technical appraisals or assessments of products made by FTSG members within the terms of approved document B Fire Spread to the Building Regulations Members of the FTSG participate on all relevant BSI committees, the equivalent ISO CEN technical committees and are involved in the EEC European Commission technical discussions on harmonisation. FTSG members have strongly supported the publication of this edition of the Yellow Book as it provides specifiers and regulatory bodies with independently validated data. It also provides a comprehensive yet concise guide to the performance of materials used to provide fire protection to structural steel. The Fire Test Study Group (FTSG) (UK) Ltd c/o Bodycote Warringtonfire Testing, Holmesfield Road, Warrington, Cheshire WA1 2DS t: Acknowledgements Permission to reproduce extracts of BS : 2003 (E) is granted by BSI. British Standards can be obtained from BSI Customer Services, 389 Chiswick High Road, London W4 4AL T: +44 (0) E: cservices@bsi-global.com The publishers wish to express their appreciation of the work undertaken by the ASFP Technical Review Panel consisting of Messrs G.Deakin and P Crewe, Bodycote Warringtonfire and Dr D.Smith and N Mcdonald of BRE FRS. The Panel has undertaken the validating and appraisal of the proprietary data sheets in this publication to maintain its unbiased technical content. The ASFP also acknowledges the valuable contributions made by Mr Gerry Newman and Ian Simms, SCI; Mr Ron Smith, previous Technical Officer ASFP for over 15 years who edited several revisions of this document; Mr John Dowling, Corus Construction; Bill Parlor, current Technical Officer ASFP; and Mrs Lisa Hennessey in the preparation and editing of the text for publication Association for Specialist Fire Protection ISBN: (4 th edition revised 7 Oct 09 Association for Specialist Fire Protection 3 Fire protection for structural steel in buildings INTRODUCTION 4 th Edition revised 7 Oct 09

4 FIRE AND YOUR LEGAL LIABILITY 2008 produced the highest UK peace time fire losses of all time, rising over the previous year by 16% to a record 1.3bn. That s why we must all play our part. Why is this of relevance to me! If you are involved in provision of a fire protection package, at any level, then you share liability for its usefulness and its operation when it s needed in fire, and that liability will still be there in the event of a court case. I place the order; it is not my responsibility to install the works! If it is your responsibility to specify the materials and/or appoint the installation contractor, it is also your responsibility to ensure that they can prove competency for the fire protection materials used, or the works to be carried out. It s no longer simply a duty of care or voluntary it s a legal obligation. If you knowingly ignore advice that leads to a failure in the fire performance of any element of installed fire protection within a building, then you are likely to be found to be just as culpable as the deficient installer. You share liability for the provision of information required under Building Regulation 16B that tells the user of the building about the fire prevention measures provided in the building. Otherwise, the user cannot make an effective risk assessment under the Regulatory Reform (Fire Safety) Order What is expected of me? In the event of fire, and deaths, a court will want to know how every fire protection system was selected; the basis for selection of the installer, whether adequate time was provided for its installation, and whether there was adequate liaison between the different parties to ensure it was installed correctly. No ifs, no buts it s all contained in the Construction, Design and Management Regulations The CDM 2007 regulations, enforced by Health and Safety Executive concentrate on managing the risk, and the health and safety of all those who build, those that use the building, those who maintain it and those that demolish it cradle to grave. Be aware the time to consider the above is before the event, not after it! Although care has been taken to ensure, to the best of our knowledge, that all data and information contained in this document is accurate to the extent that it relates to either matters of fact or accepted practice or matters of opinion at the time of publication, neither the Association for Specialist Fire Protection Limited nor the co-publishers will be liable for any technical, editorial, typographical or other errors or omissions in or misinterpretations of the data and information provided in this document. Since this document may be subject to change and updating, the data and information which it contains is only correct at the dates of the fire assessment and acceptance into this publication. The latest version of this publication is freely downloadable from the ASFP web site at The latest date is indicated at the bottom of each page. The ASFP shall not be liable for products delivered to the market, or for any aspect of withdrawn products. Compliance with this ASFP document does not of itself infer immunity from legal obligation Since this document may be subject to change and updating, it is an uncontrolled document. The data is only correct at the dates of the fire assessment and acceptance into this publication. The latest version of this publication is freely downloadable from the ASFP web site at The latest date is indicated at the bottom of each page. The ASFP offers no responsibility for products delivered to the market, or for any aspect of withdrawn products. Association for Specialist Fire Protection 4 Fire protection for structural steel in buildings INTRODUCTION 4 th Edition revised 7 Oct 09

5 Fire protection for structural steel in buildings Published by: Association for Specialist Fire Protection (ASFP) in conjunction with Fire Test Study Group (FTSG) and Steel Construction Institute (SCI) Foreword I am pleased to be able to introduce you to this updated version of the ASFP Yellow Book the original of which was introduced some 30 years ago. Throughout that period it has become a definitive reference to the provision of fire protection to structural steel in buildings, and a source of validated performance data about products for that purpose provided by ASFP members. Construction methods continue to change as new innovations are introduced. The ASFP has tried to react to those changes, and will continue to respond with regular updated electronic versions of this 4th Edition offering appropriate new text and up-to-date data on products. This edition incorporates a new section to consolidate an industry agreed protocol for the formulation of performance claims for intumescent products in the absence of a specific British Standard for their fire testing and assessment. The protocol reflects requirements for gaining European Technical Approvals and CE Marking of products, since in the next two or three years all forms of fire protection to steelwork will have to be CE Marked if they are to be placed on the European market, even if CE Marking is not mandatory in the UK. As the new European (EN) fire tests are introduced, beginning with the revision of DD ENV :2002 Applied protection to steel members which will probably be split into two parts currently drafted as pren Applied reactive protection to steel members, and pren Applied passive protection to steel members - new challenges for effective communication will arise. The revised text introduced in this 4 th Edition separates the testing and assessment methods of passive fire protection products from reactive fire protection products. This 4 th Edition of the publication recognises that in recent years the use of cellular beam constructions have increased, especially where long spans are required. These beams may feature circular, rectangular or lozenge shaped openings in the web to reduce weight and to accommodate services. It is now well known that the required thickness of any intumescent coating to provide fire protection to these types of cellular beams is product specific and that generalised rules for adoption of the data appropriate to solid sections cannot be made; the narrowness of the web post needs to be considered to establish the appropriate thickness of the coating. An explanatory section has been added to the text. Note that work on pren does not yet encompass testing and assessment of fire protection to cellular beams. Notwithstanding these changes, the traditional section factor tables have also been updated, since most steel sizes now available from UK producers have been changed in recent times. As in previous editions, an ASFP Technical Review Panel of independent experts judges the adequacy of the test and assessment data supporting every product included in this book, ably managed and supported by the ASFP Technical Officer. Appropriate acknowledgements are given in the inside cover. Readers can rest assured that all fire protective products/systems listed are capable of providing the claimed performance as given by test to appropriate BS or EN standards, as indicated in all tabulated data. However, this does not confer any reliability of performance or quality of products supplied by manufacturers to the market. This assurance can be offered by third party certification of the products. In England and Wales, the introduction of The Regulatory Reform (Fire Safety) Order 2005 and the introduction of two separate volumes of Approved Document B Fire Safety (2006 edition) has combined to present new requirements for the communication of potential hazards and associated risks within the duty for dynamic risk assessment of most buildings that are not dwellings. Similar changes are ongoing in Scotland, within The Building (Scotland) Regulations 2004 and the Technical Handbook (Fire) 2005 for Domestic and Non-domestic buildings. In Northern Ireland the relevant documents are The Building Regulations (Northern Ireland) 2000 and DFP Technical Booklet E Fire Safety The latest information can be found at either of or at or at www2.dfpni.gov.uk/buildingregulations The information used for risk assessments may become scrutinised as never before, as Fire Law adopts the same prove yourself innocent approach as existing Health and Safety legislation. I commend the Yellow Book to all, as an authoritative source of guidance, referenced in Approved Document B 2006, on the safe provision of fire resistance for structural steel frames in buildings. Geoff Deakin MBE Exova Warringtonfire Chairman of the ASFP Technical Committee Association for Specialist Fire Protection 5 Fire protection for structural steel in buildings INTRODUCTION 4 th Edition revised 7 Oct 09

6 TABLE OF CONTENTS PREFACE...7 SCOPE...7 DEFINITIONS ASPECTS OF FIRE PROTECTION Introduction Protection Methods and Fire Testing Fire Resistance Testing Assessment of fire protection materials Material thickness and steel temperature Thermal Response and Section Factor Performance of steel encased passive protection systems New steel section designations STRUCTURAL FIRE ENGINEERING Strength of steel at elevated temperature Load ratio Composite beams and voids TEST & ASSESSMENT PROCEDURES GENERAL GUIDANCE General information General test procedures General assessment procedures TEST AND ASSESSMENT PROCEDURES PASSIVE FIRE PROTECTION SYSTEMS Test programme - passive protection systems Test procedure - passive protection systems Assessment of performance of passive protection systems TEST AND ASSESSMENT PROCEDURES REACTIVE FIRE PROTECTION SYSTEMS Test programme [Reactive systems] Test procedures [Reactive systems] Assessment procedures [Reactive systems] THE FIRE PROTECTION OF CELLULAR BEAMS & CASTELLATED SECTIONS Cellular beams, including castellated sections, protected by passive fire protection systems [e.g. boards and sprays] Cellular beams protected by reactive coatings [e.g intumescent coatings] The ASFP fire testing protocol for cellular beam protection Cellular beams with rectangular openings protected by reactive coatings TEST AND ASSESSMENT METHODS TO THE EUROPEAN STANDARD ENV Introduction General Testing Protocol Test Conditions Properties of Test Component Materials Validity of the Temperature Data Correction of Temperature Data Assessment Methods Criteria for Acceptability Direct Application of Results Presentation of the Results Applicability of the Results of the Assessment to Other Section Shapes Assessment of Existing BS 476 Test Data to ENV FIRE PROTECTION PRODUCT/ SYSTEM DATA SHEETS AND THEIR APPLICATION Structural fire protection using passive products/systems Structural fire protection using reactive coatings BIBLIOGRAPHY & REFERENCES LIST OF PRODUCT DATA SHEETS...91 Association for Specialist Fire Protection 6 Fire protection for structural steel in buildings INTRODUCTION 4 th Edition revised 7 Oct 09

7 PREFACE This publication has been prepared by members of the ASFP and presents economical methods for the fire protection of structural steelwork to provide compliance with building regulations. It provides a comprehensive guide to proprietary materials and systems all of which are manufactured, marketed or site applied by members of ASFP. UK and European design codes give the engineer the opportunity to calculate the steel failure temperature as a function of the applied load level. For all fire protection materials the required thickness of fire protection will vary depending on the critical limiting temperature of the loaded steel. This edition therefore contains information for some products showing the variation of protection thickness with steel temperature. Suppliers may have more data available than is published here In the new European fire test standards the section factor is referred to as A/V but, in the UK, the term Hp/A has been used for many years to denote the section factor. In order to avoid confusion to the user of this publication, it should be noted that the terms A/V and Hp/A have very similar meaning and the reader may use either. The term Hp/A will eventually be replaced in the UK by A/V which will become the standard reference throughout Europe. SCOPE Section 1 Contains some background information into why steel often requires fire protecting and explains the basic concepts of fire testing and how to specify fire protection. It explains how the concept of Section Factor is used in the assessment of protection and gives guidance on the calculation of the Section Factor in some nonstandard cases. It features Tables of Section Factors for most sizes of currently UK produced structural steel sections. The section factor for cellular beams is discussed in Section 6. Section 2 Contains a brief introduction to structural fire engineering and specific recommendations for composite beams. Section 3 Contains general guidance of fire resistance test and assessment procedures using UK methods. These comprise assessments based on the traditional UK procedure at steel temperatures of typically 550 C or 620 C and assessments based on the traditional UK procedures but at a range of steel temperatures (350 C to 700 C). Section 4 Contains specific test and assessment procedures for passive fire protection systems (boards and sprays) using UK methods Section 5 Contains specific test and assessment procedures for reactive fire protection systems (e.g intumescent coatings) using UK methods in support of the protocol developed by the intumescent industry under the auspices of the ASFP and British Coatings Federation. Section 6 The text also includes a new text related to the fire protection of cellular beams protected from fire by passive products or reactive coatings. It also introduces a new method of determining the section factor for cellular beams. It should be noted that the scope of existing BS and EN standards do not make provision for this application. Section 7 Contains test and assessment methods to the European Standard ENV Contains fire resistance assessment procedures based on the new European procedures at a range of steel temperatures. (350 C to 700 C). Section 8 Contains notes on the application of fire protection system data sheets from which a specifier may obtain authoritative information on required thickness and range of application. Section 9 Bibiliography and References Section 10 Contains data sheets for many different fire protection systems. The data sheets indicate the limiting temperatures for the tabulated data, and any other basis for the assessment procedures. Association for Specialist Fire Protection 7 Fire protection for structural steel in buildings INTRODUCTION 4 th Edition revised 7 Oct 09

8 DEFINITIONS CEN European Committee for Standardisation. This committee is responsible for the preparation of European fire related Standards. Composite Beam A beam comprising a steel I section connected via shear connectors to a reinforced concrete or composite floor slab where the steel section and floor slab are designed to act together. Critical Temperature The temperature at which failure of the structural steel element is expected to occur against a given load level. Design Temperature The design temperature is the temperature determined by calculation at which failure of the structural steel element is expected against a given load level at a particular location in a building Fire Load The energy per square metre of floor area of the combustible material present within the internal bounding surfaces of a room, compartment or building. Fire Resistance Period The fire resistance period of each tested loaded steel section is the duration of the test until the specimen is no longer able to support the test load (see Section 1). The fire resistance of a compartment wall or floor that is penetrated by protected structure also needs to be considered, so that the required load bearing capacity, the integrity and insulation criteria of the wall are not diminished by the protected steel and fire-stopping / penetration components Intumescent Coating / reactive coating A coating which reacts to heat by swelling in a controlled manner to many times its original thickness to produce a carbonaceous char, which acts as an insulating layer to protect the steel substrate. Limiting Steel Temperature The maximum temperature of the critical element of a steel member prior to failure, under fire conditions. Orientation Plane in which the exposed face of the test specimen is located, either vertically or horizontally during testing. Passive fire protection products (e.g boards and sprays) Products which do not change their physical form on heating, providing fire protection by virtue of their physical or thermal properties Plate Thermometer A 100 x 100mm insulated thin steel plate to which a thermocouple is attached, used to measure the fire test furnace temperature(s). Reactive Fire Protection Products (e.g. intumescent coatings) Products 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.; eg intumescent products Section Factor (A/V) The rate of increase in temperature of a steel cross-section is determined by the ratio of the heated surface area (A) to the volume (V). This ratio, A/V, (also known as Hp/A), has units of m ¹ and is known as the Section Factor. Members with low section factors will heat up more slowly. In profiled protection: The ratio of the inner surface area of the fire protection material per unit length, to the cross sectional volume (area) of the steel member per unit length. In boxed protection: The ratio of the inner surface area of the smallest possible rectangle or square encasement that can be measured round the steel member per unit length to the cross sectional volume (area) of the steel member per unit length. Note that the section factor for cellular beams is calculated differently see Section 6 Steel UB or UKB Universal Beam of steel as manufactured to BS 4: Part 1: 2005 Steel UC or UKC Universal Column of steel as manufactured to BS 4: Part 1: 2005 Stickability Ability of a fire protection material to remain coherent and in position for a defined range of deformations, furnace and steel temperatures, such that its ability to provide fire protection is not impaired. UKAS United Kingdom Accreditation Service (National Accreditation of Measurement and Sampling) Association for Specialist Fire Protection 8 Fire protection for structural steel in buildings INTRODUCTION 4 th Edition revised 7 Oct 09

9 1. ASPECTS OF FIRE PROTECTION 1.1 Introduction Regulations require certain elements of structure to have fire resistance. Whether or not an element requires fire resistance depends upon such things as size, height, use and occupancy of the building and the function of the element. When exposed to fire all commonly used structural materials lose some of their strength, for example, concrete can spall exposing reinforcement, timber sections deplete by charring and steel members eventually lose strength. Heavily loaded steel will lose its design margin of safety at temperatures around 550 C regardless of the grade of steel. Members carrying appreciably less than their full capacity may remain stable at temperatures up to, and beyond 700 C. Fire resistance tests on structural steel members, performed in accordance with BS or ENV (see Sections 1.3 and 7) have shown that using the fire protection products/systems described in this publication, the load-bearing criterion of the standard test can be satisfied over a range of temperatures. Further information on structural fire engineering is given in Section 2. Where structural steel members are required to have enhanced fire resistance, they can be protected by applying insulating materials. The tabulated protection thicknesses in Section 9 include the inherent fire protection of the steel section for given exposure to fire. Alternatively, in certain cases, limited fire resistance can be achieved by virtue of the inherent fire performance of the particular steel section itself. Fire resistance tests on heavily loaded flexural and compression members have demonstrated that in certain cases a fire resistance of 15 minutes or more can be achieved without applied protection. Examples are given below Table A2 of Approved Document B: Protection Methods and Fire Testing A wide range of materials is available to enhance the fire resistance of structural steel members. They can be applied in a variety of ways to meet specific site requirements. In considering any fire protection system it is important to distinguish between profile, box and solid methods of application (Figs 1 and 2). Sprayed materials would normally be applied to follow the profile of the section. Board materials would normally be used to form a box around the section and special insulating concretes can be used to form solid protection. Details of individual fire protection products/systems are given in Section 9. Specially designed and constructed suspended ceilings utilising lightweight metal support components, insulating tiles and panels, and sprayed or trowelled compounds on suspended lath, tested in accordance with BS or ENV may also be used for the protection of structural steel but they are beyond the scope of this publication. Fire tests on elements of building construction have been carried out in accordance with the methods in the various Parts of BS 476. The BS 476 series is being replaced by European fire testing standards (See Sections 1.3 and 7). These already coexist in the guidance within Approved Document B: The two standards are generally similar but differ in a number of details. The adoption of the European standard is intended to remove technical barriers to trade within Europe. The international fire testing standard, ISO 834, is similar to the other standards and is in the process of being revised to bring it more in line with the European standard. It is hoped that eventually there will be a basis for international test data exchange. Figure 1: Protection technique for three-sided protection Profile Box Solid (with or without gap over flanges) Association for Specialist Fire Protection 9 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

10 Figure 2: Protection technique for four-sided protection Profile Box Solid (with or without gap over flanges) The size and construction of a test specimen would ideally be identical with the element in its intended position in a building. In a BS 476 test, loaded beams are tested horizontally with protection applied to three sides and with the top flange directly in contact with a floor slab. Columns are tested vertically with the protection applied to all sides. It is therefore common to meet the terms three sided and four sided exposure when dealing with fire protection to steelwork. When assessing a material to ENV Part 4 or to the draft pren Part 8 the required tests are slightly different. Beams are tested with a layer of insulation between the top flange and the floor slab and a loaded test on a column is generally not required. It is common when referring to the testing and use of fire protection to use the term orientation to mean horizontally, as a beam, or vertically, as a column. The term orientation is used throughout this publication. The data sheets in this publication have largely been derived from tests carried out at the BRE/FRS fire laboratory at Garston, Watford, UK, or at Bodycote Warringtonfire, together with support data from other laboratories. The UK test facilities are approved for this test work under the UKAS scheme. The results of a standard fire resistance test relate to the steel section size and loading, together with the thickness and performance of the protection system. To repeat the procedure to explore those important and numerous variables for all steel sections and protection parameters would be prohibitive. Assessment procedures have therefore been developed which allow the performance of a range of steel sections to be estimated from the information gained from a limited number of tests. 1.3 Fire Resistance Testing Fire test standards The general procedures used for determining the fire resistance of load-bearing elements of structure are specified in BS476 series. In assessing the performance of fire protection materials the relevant parts are: Part 20 Method of determination of the fire resistance of elements of construction (general principles) Part 21 Method of determination of the fire resistance of load-bearing elements of construction Whilst BS 476 Part 20 is concerned with general principles and covers requirements which are common to the other Parts of BS 476, the BS 476 Part 21 fire resistance testing covers load-bearing elements of construction, such as steel beams, columns or walls, whilst BS 476 Part 22 fire resistance tests are intended for non load-bearing elements of construction European fire testing standards have been published. In assessing the performance of fire protection materials the relevant part is presently ENV Test methods for determining the contribution to the fire resistance of structural members Part 4: Applied protection to steel members. This standard makes reference to the EN 1363 Series of standards which contain general information about conducting fire resistance tests. However, as all the procedures for assessing fire protection are currently specified in ENV , it is this standard which is generally referred to in this publication. The European standards will gradually replace the British Standards. ENV has no parallel British Standard. In the UK, it is generally accepted that the procedures for determining the contribution of applied protection to the fire resistance of steel members are covered by this ASFP publication. In both BS476 and the new European Standards the fire resistance performance of an element is judged against the three criteria of load-bearing capacity, integrity and insulation. The European Classification System will use the abbreviations of R, E and I respectively for these three criteria;- Association for Specialist Fire Protection 10 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

11 Resistance to collapse [load-bearing capacity (R)] is the ability of the element to remain in place and support the required load without excessive deformation. Resistance to fire penetration [integrity (E)] is the ability of the element to resist the passage of flame and hot gases and also, not to exhibit flame on the unexposed side. Resistance to the transfer of excessive heat [insulation (I)] is the ability of the element to resist the passage of heat by conduction., and may be of particular importance where steel structure passes through compartments, or fire resisting walls or floors The use of REI terminology has already become more common. Note the requirement to maintain REI for compartment walls and floors penetrated by protected steel. Simple linear elements such as beams or columns are only judged against loadbearing capacity for the fire resistance period under consideration. Separating elements, such as floors or walls, are judged against all three criteria Description of Fire tests to BS476 Beams are tested horizontally in conjunction with a floor slab (Figure 3) and columns are tested vertically (Figure 4). Currently in the UK, loaded beam tests are carried out on a nominal span of 4.25 metres using a 305x127x42 Universal Beam for passive insulating materials and a 406x178x60 Universal Beam for intumescent coatings. Loaded column tests are normally carried out on a 203 x 203 x 52 kg/m Universal Column with an exposed length of at least 3 metres (Figure 4). The specimen is initially held vertically and, although it has freedom to expand longitudinally, its ends are rotationally fixed so that, structurally, an effective length factor of 0.7 can be assumed. It is then axially loaded to develop the required stress which is normally the maximum permitted by design. The level of the applied load traditionally used in the UK is slightly lower than that specified in the new European EN standard. The higher EN load could make the test more onerous in that the ability of the fire protection to maintain its stickability could be affected. However, any difference in the final assessed thickness of protection required to keep a steel member below a specified temperature is likely to be insignificant. It is usual to include information on the fire insulating properties of fire protection materials obtained from tests performed on unloaded exploratory specimens (about 1m in length). This information is used in both the UK and European methods of assessing fire protection materials, and is often combined with loaded tests to form a complete test package. The procedures used in most UK fire testing laboratories have been agreed and standardised through the Fire Test Study Group, which embraces members from UKAS approved fire testing laboratories, representatives from the UKAS executive and BRE Fire Research Station, to ensure that consistent techniques are adopted in the generation of data for appraisal purposes. It is recognised that varying results can be obtained on identical specimens tested in different furnaces. To reduce the effect of such variations, the UK laboratories use common preparation, testing and measuring techniques. Figure 3: General arrangement for BS 476 fire tests on beams Furnace cover slab Seal LOAD Concrete cover Slab to steel beam Furnace cover slab Association for Specialist Fire Protection 11 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

12 1.3.2 Description of fire tests to ENV The testing programme for the assessment of a fire protection material to ENV differs in a number of respects from the BS 476 programme. The main difference is that a loaded column test is not required in the European Standard, except for products which are only used for protecting columns. The other main difference is that, for the loaded beam test, a layer of insulation is placed between the top flange of the beam and an ultra lightweight concrete floor slab. This serves to reduce the heat sink effect of the slab and to minimise the effects of composite action. UK beam tests use a segmented dense concrete slab in intimate contact with the top flange of the beam. The European procedures do not always require a loaded column to be tested. However, when assessing intumescent coatings, an unloaded column 2000mm high must be tested to assess stickability. Another major difference between European and UK testing is in the type of furnace thermocouple used. The European test uses a plate thermometer. This a special type of thermocouple used for measuring the temperature within the furnace. It consists of a small plate, insulated on one side, with a thermocouple welded to its centre. The plate thermometer is intended to reduce the differences between fire tests carried out in different furnaces and thus to promote European harmonisation. Figure 4: General arrangement for BS 476 fire tests on loaded columns Association for Specialist Fire Protection 12 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

13 1.4 Assessment of fire protection materials Methods of assessing the performance of fire protection materials have been developed which enable the thickness of protection for a wide range of situations to be predicted. The procedure is in two parts. Firstly, a carefully designed programme of fire tests is carried out on both loaded and unloaded specimens and, secondly, a mathematical procedure is applied to the results of the tests which enables predictions of required thickness to be made. These programmes of tests are designed to determine both the insulation characteristics of a fire protection material and its physical performance under fire conditions for a range of steel sizes (in terms of Section Factor, protection thicknesses and fire resistance periods). They generate the maximum amount of data from a minimum number of tests. A method of assessing fire protection materials has been developed and used in the UK for a number of years. It was used to generate the data in the earlier editions of this publication and is one of the methods used in this edition. More recently, European methods of assessing fire protection materials have been developed. These methods have been formally codified in ENV In a similar programme of tests to those already used in the UK, both loaded and unloaded specimens are tested and an appraisal of the fire protection material is derived. The method has a number of technical differences from the UK procedure which make an exact comparison difficult. Further information on fire resistance testing, programming and the assessment procedures are given in Sections 3, 4 and 5 - for general conditions, for passive [e.g. boards and sprays] and for reactive fire protection systems [e.g intumescent coatings] respectively. 1.5 Material thickness and steel temperature In this publication, the thickness of fire protection materials to maintain steel sections below specified temperatures is given in product data tables. It is important that the basis for these temperatures is understood. In the 1 st and 2 nd editions of this publication, the thickness of fire protection was specified such that the maximum temperatures of 550 C for columns, and 620 C for beams (supporting concrete floors), were not exceeded for a given period of fire resistance. This assumed that the structural section was fairly heavily loaded at the time of the fire, together with a simplistic representation of the behaviour of steel at elevated temperatures. Since the introduction of these temperatures, we have improved understanding of how steel columns and beams behave in fire, resulting in the development of fire design codes. It is now known that the original approach was almost invariably conservative, but, in some limited cases can be shown to be unconservative. Using fire design codes such as BS :2003 or the Structural Eurocodes, EC and EC 4-1.2, designated ENV and ENV , the load on the structure at the time of the fire can be calculated by treating it as an accidental limit state. If used, this will allow structural fire designers to specify a limiting or failure temperature for a given structural section, to the fire protection contractor. The protection contractor will then be able to use the required thickness of material to ensure that the steel section does not exceed this temperature, within the fire resistance period. This process could be simplified by the designer specifying a maximum steel temperature, based on the worst case, for all beams or columns on one floor level. If the structural fire design codes are not used to calculate the maximum allowable temperature in the steel sections, then the temperatures of 550 C and 620 C, used earlier, may not always be appropriate and some reference to the composite or non-composite steel members and the usage of the proposed building should be made, see Table 1. Buildings such as offices, residences, schools, hospitals, etc, which are not used for storage, have a high percentage of non-permanent loads. For this type of building, the structural codes, BS and ENV (the loading code) assume that a proportion of the design load will not be present at the time of the fire. Other types of buildings such as warehouses, libraries, etc are primarily used for storage, so a high percentage of load is permanent, and the codes allow no reduction in design load for the fire condition. Note that in BS 5950 Part 8:2003 the load factor for offices has been reduced from a generalised value of 0.6, as used in previous Editions, to a lower value of 0.5. This means that the failure temperature will increase marginally. In fire, it is permissible to consider only the strength of an element. The fire testing standards, such as BS 476, effectively base the failure criteria for load-bearing elements on strength. However, beams are often designed for serviceability (deflection) requirements which mean that their strength is not fully utilised in the cold state and they would therefore have an additional reserve of strength at the fire limit state. Columns are frequently constructed so that a single length will be two or three storeys high. The lowest storey will be the highest loaded but the upper storey will be very lightly loaded. Another factor affecting the failure temperature in fire is that there Association for Specialist Fire Protection 13 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

14 are only a finite number of serial sizes. The designer is almost invariably forced to use the next size up. Steel members which, in terms of strength, are not fully utilised in the normal, cold, state will have reduced load ratios in the fire limit state Performance criteria In case of a fire, the mechanical resistance of the entire structure or individual structural members should be designed and constructed in such a way that their load bearing function is maintained under the factored loads for permanent or non-permanent loads during the relevant fire exposure. The load factors for the fire limit state are provided in Table 5 of BS 5950 Part 8:2003. Any specified design or regulatory requirements for the insulation and integrity of compartment walls and floors, including any incorporated members, should also be satisfied Limiting temperatures The limiting temperatures shown in Table 1, are provided for various categories as listed, for a range of load ratios based on BS : They may be used to determine the behaviour in fire of columns, tension members and beams with low shear load, designed in accordance with BS :2000. Table 1 Limiting temperatures for the design of protected and unprotected hot finished members Description of steel member Limiting temperature [degrees C] at a load ratio of (2) Members in compression, for a slenderness > 70 but Non-composite members in bending supporting concrete slabs or composite slabs: Unprotected members or protected members complying with of BS Other protected members Composite members in bending supporting concrete slabs or composite slabs: Unprotected members, or protected members complying with of BS [i] 100% degree of shear connection [ii] 40% degree of shear connection (2) 600 (2) 610 (2) 635 (2) Other protected members - [i] 100% degree of shear connection [ii] 40% degree of shear connection Members in bending not supporting concrete slabs: Unprotected members, or protected members complying with of BS Other protected members Members in tension: all cases NOTE For beams supporting a composite slab, the limiting temperatures only apply when the voids between the top of the beam and underside of the steel deck are filled with non-combustible void fillers. Also see 2.3 of this ASFP publication SCI 4 November 1997 The existing temperatures of 550C and 620C are acceptable for most circumstances, but they are not always conservative. A suitable statement must be provided in all contracts and quotations Association for Specialist Fire Protection 14 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

15 NOTE 1 - The ratio of the load or moment carried by a steel member at the time of a fire compared to the strength of the member at normal temperatures is called the load ratio. For practical designs the load ratio will vary between approximately 0.4 to The higher the load ratio, the lower the failure temperature. NOTE 2 It is important to recognise that changes have been introduced to the text in this 4 th Edition when compared to the data in earlier Editions. These changes arise from the revision of load factors in BS : [a] For example, the load factor for Offices has been reduced from 0.6 for general buildings, to a lower value of 0.5 in BS 5950 Part 8:2003. This means that the failure temperature will increase marginally. The load ratio is higher in storage buildings but not usually above This has an effect on the limiting temperature as shown in Table 1. [b] [c] It is also important to differentiate between the effect on limiting temperature from non-composite decks and composite decks with different levels of shear connection as shown in Table 1, as extracted from BS5950-8:2003 Roof loading is non-permanent in nature regardless of the use of a building. Therefore, in assessing the appropriate steel temperature of columns and beams supporting roofs in storage buildings, the higher steel temperatures appropriate for offices etc should be used. NOTE 3 - Users of the tabulated data should be aware of the lower recommended temperatures for storage buildings. As the limiting temperatures assumed may affect the thickness and cost of fire protection, users of the data are reminded that the basis on which the thicknesses are specified in contracts should be clear to all parties. NOTE 4 - In Section 9, fire protection system thicknesses are given for typical steel temperatures. It is the responsibility of the design engineer, using design codes such as BS or ENV , to specify the appropriate limiting steel temperatures. 1.6 Thermal Response and Section Factor The rate of increase in temperature of a steel cross-section is determined by the ratio of the heated surface area (A) to the volume (V). This ratio, A/V, has units of m -1 and is known as the Section Factor. Members with low Section Factors will heat up more slowly, and this is shown diagrammatically in Figure 5. Figure 5: Concept of the section factor Section Factor = A/V where A = surface area of steel exposed to fire per unit of length V = Volume of the section per unit length High A Low V Fast Heating Low A High V Slow Heating In earlier editions of this publication the Section Factor was written as Hp/A. In the new European testing and design standards (ENV , ENV and ENV ) the Section Factor is presented as A/V, which generally has the same numerical value as Hp/A. It is likely that the designation Hp/A will gradually fall into disuse. Throughout this publication the term A/V will be used. A steel section with a large surface area (A) will receive more heat than one with a smaller surface area. Also, the greater the volume (V) of the section, the greater is the heat sink. It follows therefore, that a small thick section will be slower to increase in temperature than a large thin one. The Section Factor (A/V) is thus a measure of the rate at which a section will heat up in a fire. The higher the value of the Section Factor the greater will be the protection thickness required. Values of Section Factor, rounded to the nearest 5 units, for the range of sections for fire Association for Specialist Fire Protection 15 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

16 exposure on both three and four sides are given in Tables 3 to 15. Figure 6 illustrates the appropriate perimeter dimension to be used when calculating the Section Factor for a variety of steel sections in different situations. In calculating the Section Factor values the full volume, V, is used whether the section is exposed on three or four sides as the whole of the steel section will be receiving heat. The value of A is the exposed surface area and that depends on the configuration of the fire protection. In the case of a box protection, the surface area is taken as the sum of the inside dimensions of the smallest possible rectangular or square encasement (except for circular hollow sections - see Figure 6) whilst for a profile protection, it is taken as the external surface area of the steel section itself. Where a section supports a floor or is against a wall which themselves provide fire protection, the surface in contact is ignored in calculating A. For solid protection the Section Factor value should be taken as that for box protection. Where a spray or trowelled system has been tested as a profile protection, the use of the same material as a box protection is permissible, provided there is adequate evidence of physical performance (commonly referred to as stickability ). In the absence of a full programme of tests on the system as a boxed protection, the thickness should be derived on the basis of the Section Factor for the profiled application In some cases the appropriate Section Factor may not be based on simple geometric considerations. Guidance on some common cases is given below Section Factor (1400/t) for cellular beams including castellated sections Cellular beams To satisfy building design requirements, steel beams are now available with a variety of apertures created in the basic section size, during a secondary manufacturing process, to form deeper cellular beams than the parent beam. Alternatively, cellular beams can be created from three flat steel plates welded together. Whilst rectangular and/or elliptical elongated aperture shapes are available, most apertures are circular in shape. A large range of circular aperture sizes and spacing/pitch is available. The dimensions of the residual web post can significantly affect the performance of the cellular beam in fire. The method of calculating section factor AND fire protection thickness for cellular beams is considered to be different than for other solid steel sections. Different approaches have been introduced for the use of passive fire protection products (boards and sprays) and reactive coatings (intumescent products). The issue is discussed further in Section 6. Castellated sections This publication considers that castellated beams are one form of cellular beams. Fire test experience has shown that the temperature of castellated members may increase at a slightly faster rate than the conventional parent sections and that an increase in the fire protection thickness is prudent. Although minimal steel is effectively removed from the parent steel section volume, the steel depth is increased. N.B. In previous editions of this publication, it has been recommended that to obtain the thickness of passive fire protection [boards and sprays] for a castellated section, the thickness of fire protection should first be obtained based on the section factor as determined for the original parent steel section and then increased by 20%, for the installed fire protection product. This guidance is now withdrawn and replaced by new guidance for cellular beams in Section 6. Furthermore, the 20% rule does not apply when using reactive coatings [e.g intumescent paint] for the fire protection of castellated sections and cellular beams. New recommendations are also provided in Section Section Factor (A/V) for structural hollow sections Other than where stated in Section 2, the fire test data relates specifically to universal beams and columns, as the bulk of test work over the years has concentrated on these sections. However, test data exists on structural hollow sections (SHS) as compression and flexural members, and the comparability between SHS sections and I sections in terms of protection thickness related to Section Factor, for rectangular, square and circular sections, has been established. The same critical temperatures can be adopted for analysis purposes for SHS and I sections. The modifications listed below would not apply to intumescent coatings. Guidance on fire protection with intumescent coatings is presented in Section 5. Association for Specialist Fire Protection 16 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

17 For fire protection materials, whether boards or spray (on lath), whose thicknesses have been assessed from test data on boxed I sections (see Figure 1), no change in thickness is required, i.e. the thickness for an SHS of a given Section Factor, is equal to that for the I section of the same box Section Factor. For fire protection materials, whether board or spray whose thickness has been assessed from test data on profiled I sections (see Figure 2), some modification in thickness is required. The extent of the modification is related to the Section Factor of the section and is derived as follows: (a) (b) (c) Establish the Section Factor of the SHS section. Establish the required thickness of profiled protection material based upon the tables relating to Section Factor and fire resistance period and protection thickness, derived for I sections. This is the thickness d p (mm). Increase thickness d p as follows For Section Factor up to 250m -1 Modified thickness = d p 1 + A/V 1000 For Section Factor between 250 to 310m -1 Modified thickness = 1.25 d p NOTE 1 - The maximum thickness that can be applied to SHS sections should not exceed that given for I sections listed under item 11 of the data sheet (see in Section 7). NOTE 2 - It should be noted that any changes resulting from the transposition from I sections to SHS sections may affect the retention of the material. Where modifications are considered significant, appropriate loaded fire resistance tests should be carried out. NOTE 3 - Where the fire protection thickness of I sections has been established by a test conducted on members which were solid protected, then a separate appraisal for the hollow section is necessary Section Factor for partially exposed members When a section is partially exposed to fire, for instance when a column is built into a wall or a beam is embedded in a floor slab, and robust construction materials such as brick, block or concrete have been used, the Section Factor may be traditionally calculated as shown in Figure 6. In such situations the same principle is used as for other configurations where A is the surface area of the part of the section exposed to the fire and V is the volume of the section. The Section Factor will change depending upon the degree of exposure and the equations given in Figure 6 can be used. It should be noted that the calculation method in Table 4.2 of Eurocode EN :2005, for unprotected steel members uses a more conservative value for the Section Factor[A/V] as calculated by division of the exposed steel perimeter [A EXP ] by the exposed steel cross section area [V EXP ] rather than the entire volume of the steel section, despite the fact that heat is conducted into the entire volume of the steel section and also into the mass in contact with the embedded steel surface. That is, for partially exposed unprotected steel, the Eurocode Section Factor (A/V) = (A EXP / V EXP ) Notwithstanding the above, for partially exposed steelwork, separate consideration should be given to the stability of the encompassing wall or partition in fire, since this will play a part in the conduction of heat away from the steel, as will the thermal conductance at the contact points. Being mindful of modern trends towards greater use of lightweight wall and sandwich panel or partition constructions, the method generally used in Figure 6 may no longer be as generally applicable when steel is not embedded in robust walls such as brick, block or concrete. In the case of lightweight walls/partitions it would be prudent to assume that the entire perimeter of the steel may become exposed to fire, and the Section Factor should then be calculated in the traditional manner. Note that where the steel section penetrates through both sides of a fire resisting construction, the thickness of protection may be determined by other requirements, such as compliance with the appropriate integrity and/or insulation requirements of BS 476 for elements performing a fire separation function. As an example, consider a steel section partially exposed on both sides of a wall or floor as shown in Figure 6. Different approaches should be followed according to the degree of fire resistance required of the wall or floor, whether it be similar to or less than that of the steel member, or zero. In the case of walls, for example, the following have to be considered: (a) Solid masonry or concrete wall having comparable fire resistance. Association for Specialist Fire Protection 17 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

18 (b) Since the insulation criterion must be satisfied for both steel member and wall, the thickness of protection to the exposed steel should be sufficient to ensure that the rise in mean surface temperature of the protection on the side remote from the fire does not exceed 140 C, and the rise in maximum surface temperature does not exceed 180 C. In assessing fire protection requirements to maintain the structural performance of the column, the exposed steel on each side of the wall will have its own heated surface area, A, and therefore its own A/V, consequently different protection thicknesses may be required on each side depending upon the degree of exposure. Walls having lower fire resistance or formed from material which will degrade when exposed to fire, e.g. timber stud with combustible facings. The effective surface area will relate to all steel which has the potential of becoming exposed and the fire protection should be applied in such a manner that its performance is independent of the wall. In some load bearing walls, simultaneous attack from fire on both sides may occur on columns partially exposed within the wall. Where this occurs, the Section Factor must be based on the sum of the fire exposed areas, either side of the wall, and the total volume of the section Section Factor (A/V) for wind and stability bracing [extracted from BS :2003] The apparent cost of fire protecting bracing members is often expected to be high because the members are comparatively light and therefore have high Section Factors and correspondingly require high thicknesses of fire protection. However, for the reasons now discussed BS :2003 recommends that the fire protection thickness should be based on the section factor of the steel member, or a value of 200-1, whichever is the smaller value. In some cases, it might not be necessary to apply fire protection to bracing members and consideration should be given to: a) Shielding bracing from fire by installing it in shafts or within walls. b) The use of infill masonry walls, which can provide the sufficient shear capacity during a fire instead of relying on the steel bracing systems c) The possibility that only bracing systems within a fire compartment might be subjected to elevated temperatures and the other unaffected bracing systems might be sufficient to provide the required stability at the fire limit state. d) The possibility that the steel beam to column connections might have sufficient stiffness to ensure stability at the fire limit state The recommendations in previous Editions for fire protection to bracing members are retained in Table 2. Building Single storey Not more than 8m to eaves Single storey More than 8m to eaves Two storey Other multi-storey Table 2: Assessment of fire protection requirements for bracing Degree of fire protection to bracing system Association for Specialist Fire Protection 18 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09 None Generally none Generally none Walls and frame stiffness will contribute considerably to stability. Protected to achieve required fire resistance. However the selection of thickness may be based on allowable reductions in applied loads in fire given in BS Section Factor (A/V) for tees, angles, channels Where these sections are used structurally, it is necessary to determine the A/V values using the surface area, A, values illustrated in Figure 6. Where such members are considered as wind bracing, a modified approach is recommended and is discussed in the following section Tapered sections Use the maximum section factor for the tapered steel section

19 1.6.7 Section Factor (A/V) for lattice members Ideally, wherever possible, a lattice beam should be judged by a full test as a loaded member. However, with existing fire testing equipment this is not always practicable and recourse to appraisal using A/V can be made. When the elements of a lattice beam are to be individually protected, the thickness of protection required for each element should be based on the Section Factor of the individual element. Where a lattice beam is to be protected by encasing the entire beam by either boards, or sprays applied to an expanded metal lathing, no recommendation can be given and each case must be considered on its own merits, according to any test information available. The use of the limiting temperature method of BS : 2003 or the similar EC3-1.2 method is not recommended for the diagonal bracing members because these members might be subject to significant thermal stresses from restrained thermal expansion. In the absence of a detailed analysis a general steel temperature of 550 C is recommended. In any case it is important that the final appraisal be based on a broad consideration of the lattice design Light gauge cold rolled sections This type of section would normally necessitate separate appraisal because of the high values of A/V and the manner in which the sections are formed which can influence their failure criteria. Research is continuing to formulate recommendations for the applications of data given in this publication. Some information on the protection of cold formed members is given in the SCI publication Building design using cold formed members. There are a variety of sections formed from cold rolled sections and normally each would require separate appraisal Unprotected steel According to BS :2003, fire resistance tests have demonstrated that 30 minutes fire resistance can be achieved with fully stressed unprotected steel sections as follows: Rolled steel section columns filled with aerated concrete blockwork between the flanges A/V up to 69m -1 Columns, in simple construction, four sided exposure - A/V up to 50m -1 Beams, in bending, directly supporting concrete or composite slabs - A/V up to 90m -1 Where these specific conditions arise on site, protection may not be necessary subject to agreement with the approving authority Novel steel beam designs Steel manufacturers may have different approaches to novel steel beam designs in buildings. For example, in the UK, Slimflor and Slimdek are the trade names for a form of shallow floor construction developed by Corus. There are three forms available as briefly described below. Other variations of a similar or different approach may be available from suppliers located in other countries Slimflor with precast planks In this form, the beam is manufactured by welding a plate to a column section. The floor is then created by laying a pre-cast concrete floor slab on the outstand of the plate. In situations where fire protection is required, the bottom plate only should be protected. As with standard downstand beams, the protection material thickness is based on the section factor and for calculation purposes, the heated perimeter is the width of the plate plus 2 x plate thickness, in metres, divided by the cross sectional area of the column section and plate combined. This will usually result in low section factors. Slimflor with deep decking In this form, the beam is also manufactured by welding a plate to a column section. However the floor is then created by laying a deep metal deck on the outstand of the plate. The deck is then filled with in-situ concrete. When fire protection is required, the bottom plate only should be protected. As with standard down-stand beams, the protection material thickness is based on the section factor and this calculation is identical to that for Slimflor with pre-cast planks. This will also usually result in low section factors. Association for Specialist Fire Protection 19 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

20 Slimdek flooring systems In this form, the beam is a rolled asymmetric section with the lower flange wider than the upper. The floor is created by laying a deep metal deck on the outstand of the bottom plate. The deck is then filled with in-situ concrete. The beams are normally rolled with a thick web and, in the fire condition, this web takes much of the load shed by the hot bottom flange. Where the thick web is not sufficient to compensate for the loss in strength of the flange, it is usually more economic for the designer to use a beam without a thick web. Asymmetric Slimdek Beams with a fire engineered (thick) web are designated ASB(FE); those without the thick web are designated ASB. As previously stated, when fire protection is required, the bottom flange only should be protected. For calculation purposes the heated perimeter is also taken as the width of the bottom flange plus 2 x bottom flange thickness, in metres, divided by the cross sectional area of the ASB. This will also usually result in low section factors. Contact should be made with Corus Steel for further information relating to the above systems Galvanised surfaces The application of intumescent (reactive) coatings to galvanised surfaces may occur either off-site in a factory controlled environment or on-site during the construction of the building. OFF SITE: Steel Construction Institute publication P160 Structural fire design: Offsite applied thin film intumescent coatings (2 nd edition) makes reference to substrate preparation in Section 4.1 of that document. ONSITE: ASFP technical guidance documents provide advice for the application of different types of fire protection systems in relevant documents. [a] TGD11 Code of practice for the specification and on-site installation of intumescent coatings for the fire protection of structural steelwork contains Section 3.4 with specific advice for the preparation of galvanised steelwork before coatings are applied. [b] TGD 15 Code of practice for the installation and inspection of sprayed non-reactive coatings for the fire protection of structural steelwork contains Section 4 and 4.4 in relation to preparation of substrates and galvanised steelwork. 1.7 Performance of steel encased passive protection systems To assess the performance of a steel encased protection system, a fire resistance test should be performed for the maximum fire resistance period on a fully loaded specimen in the orientation in which the system is to be assessed. The fire resistance test shall be performed on the steel encased protection system incorporating the board to be used in practice. The performance of the structural member fitted with the steel encased protection system in the test shall be compared with the value(s) taken from the appropriate data sheet(s) at the required critical steel temperature(s) derived from tests of the structural member protected with the same material but without the steel encasement. (i) (ii) If the fire performance achieved by the steel encased specimen is greater than, or equal to the fire performance of the specimen without the steel encasement, the data sheets for the protection material without the encasement can be used for the steel encased protection system without correction. The same test data may be used to show the suitability of other protection materials of similar type. If the fire performance achieved at the required critical steel temperature is less than the value expected from test data for the protection system without the steel encasement the data sheet for the encased system shall be modified by the use of a correction factor to bring the two sets of information into agreement. 1.8 New steel section designations As part of the process of compliance with European Construction Products Directive [CPD 89/106/EEC], steel sections may be encountered with amended prefixes for relevant applications, as follows Universal beams - UB becomes UKB; Universal columns - UC becomes UKC Parallel flange channels - PFC becomes UKPFC Asymmetric Slimflor Beams - ASB Slimflor beams - SFB Angles UKA Tees - UKT Association for Specialist Fire Protection 20 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

21 NOTE 1- The figures for section factors in the following Tables 3-15 have been provided by Corus and include corner radii. They may therefore vary from simpler calculation of similar steel sizes from other sources. NOTE 2 - That in Figure 6, that follows, calculations for 1 sided exposure should reflect the text in NOTE 3 The dimensions of historically available steel sections and steel sections from other sources will be made available in the Technical Section of the ASFP web site Association for Specialist Fire Protection 21 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

22 Figure 6: 6: Protection configurations with values of perimeter Hp for use in the calculation of section factor Hp/A (A/V) Note: the values are approximate in in that radii at at corners and and roots roots of all of all sections may are be ignored. In this figure Hp/A = A/V Steel section Profile protection Universal beams, universal columns and joists (plain and castellated) 4 sides 3 sides 3 sides 2 sides 1 side d D t Partially exposed Partially exposed B Hp 2B + 2D + 2(B - t) = 4B + 2D - 2t B + 2D + 2(B - t) = 3B + 2D - 2t B + 2d + (B - t) = 2B + 2d - t B + D + 2(B - t)/2 = 2B + D - t B Structural and rolled tees 4 sides 3 sides 3 sides B D t Flange to soffit Toe of web to soffit Hp 2B + 2D B + 2D B + 2D + (B - t) = 2B + 2D - t Angles 4 sides 3 sides 3 sides D B t Flange to soffit Toe of flange to soffit t Hp 2B + 2D B + 2D B + 2D + (B - t) = 2B + 2D - t Channels 4 sides 3 sides 3 sides B D t Web to soffit Flange to soffit Hp 2B + 2D + 2(B - t) = 4B + 2D - 2t 2B + D + 2(B - t) = 4B + D - 2t B + 2D + 2(B - t) = 3B + 2D - 2t Hollow sections, square or rectangular 4 sides 3 sides B D Hp 2B + 2D B + 2D Hollow sections, circular D Hp πd Example using 203 x 203 x 52 kg/m universal beam B = 204.3mm 203.9mm; D D = 206.2mm = 206.2mm t = 8.0 mm. A = 66.4 cm² t = 7.9mm A = cm2 a) Profile protection - 4 sided exposure b) Profile protection - 3 sided exposure Hp = 4B + 2D - 2t Hp = 4B+2D-2t=[4x204.3]+[2x206.2]-[2x7.9] Hp = 4 x x x 8.0 = =1213.8mm=1.214m = 1212 mm = m Hp/A = 1.214/ m -1 Hp/A = 1.212/ = m Hp Hp = = 3B 3B+2D-2t= t Hp = = mm=1.01m = 1008 mm = m Hp/A = 1.01/ = 152.4m -1 Hp/A = 1.008/ = m -1-1 Association for Specialist Fire Protection 22 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

23 Figure 6 (continued) In this figure Hp/A = A/V Steel section Box and solid protection Universal beams, universal columns and joists (plain and castellated) 4 sides 3 sides 3 sides 2 sides 1 side d Partially exposed Partially exposed Hp 2B + 2D B + 2D B + 2d B + D B Structural and rolled tees 4 sides 3 sides 3 sides Flange to soffit Toe of web to soffit Hp 2B + 2D B + 2D B + 2D Angles 4 sides 3 sides 3 sides Flange to soffit Toe of flange to soffit Hp 2B + 2D B + 2D B + 2D Channels 4 sides 3 sides 3 sides Web to soffit Flange to soffit Hp 2B + 2D 2B + D B + 2D Hollow sections, square or rectangular 4 sides 3 sides Hp 2B + 2D B + 2D Hollow sections, circular Hp πd Note. The air space created in boxing a section improves the insulation and a value of Hp/A, and therefore Hp, higher than for profile protection would be anomalous. Hence Hp is taken as the circumference of the tube and not 4D. Example continued c) c) Box Box - 4 sided protection exposure 4 sided exposure d) Box d) - 3 sided Box exposure protection 3 sided exposure Hp Hp = 2B + 2D = = 3B + 2D 2t = = mm = = mm 1.01m = m Hp Hp = B + 2D = = B +2D = = 616.7mm = 0.617m m Hp/A = -1 Hp/A = / 0.82/ = m m Hp/A -1 Hp/A = = 0.617/ / = 92.8 = 93.04m m Association for Specialist Fire Protection 23 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

24 Table 3: October 2006 UK Beams (UKB) Section factor A/V(Hp/A) Profile Box 3 sides 4 sides 3 sides 4sides Dimensions to BS4 Part 1:2005 Designation Thickness Depth of Width of Area of Mass per Flange Serial size section D section B Web t section metre T mm kg mm mm mm mm cm 2 m -1 m -1 m -1 m x x x x x x x x x x x continued overleaf Association for Specialist Fire Protection 24 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

25 Table 3: October 2006 UK Beams (UKB) Section factor A/V(Hp/A) Profile Box 3 sides 4 sides 3 sides 4sides Dimensions to BS4 Part 1:2005 Designation Thickness Depth of Width of Area of Mass per Flange Serial size section D section B Web t section metre T mm kg mm mm mm mm cm 2 m -1 m -1 m -1 m x x x x x x x x x x x x continued overleaf Association for Specialist Fire Protection 25 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

26 Table 3: October 2006 UK Beams (UKB) Section factor A/V(Hp/A) Profile Box 3 sides 4 sides 3 sides 4sides Dimensions to BS4 Part 1:2005 Designation Thickness Depth of Width of Area of Mass per Flange Serial size section D section B Web t section metre T mm kg mm mm mm mm cm 2 m -1 m -1 m -1 m x x x x x NB - Data on older and other steel sizes can be found on ASFP website/technical section Association for Specialist Fire Protection 26 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

27 Table 4: October 2006 Columns (UKC) Section factora/v(hp/a) Profile Box 3 sides 4 sides 3 sides 4sides Dimensions to BS4 Part 1:2005 Designation Thickness Area of Mass per Depth of Width of Web Flange Serial size section metre section D section B t T mm kg mm mm mm mm cm 2 m -1 m -1 m -1 m x x x x x x Association for Specialist Fire Protection 27 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

28 Table 5: July 06 JOISTS Section factor A/V (Hp/A) Profile Box 3 sides 4 sides 3 sides 4sides Dimensions to BS 4 Part 1:1993 Designation Thickness Area of Mass per Depth of Width of Web Flange Serial size section metre section D section B t T mm kg mm mm mm mm cm 2 m -1 m -1 m -1 m X X Table 6: October 2006 Parallel Flange Channels Dimensions to BS 4 Part 1: 2005 Designation Depth Width Mass of of Serial size per section section metre D B Thickness Web t Flange T Area of section Section factor A/V (Hp/A) Profile 4 3 sides sides 3 sides mm Kg mm mm mm mm cm 2 m -1 m -1 m -1 m -1 m -1 m -1 m -1 m x x x x x x x x x x x x x x x x Box 4 sides NB Data on older and other steel sizes can be found on ASFP website / technical section Association for Specialist Fire Protection 28 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

29 Table 7: October 2006 Equal Angles (UKA) Section factor A/V (Hp/A) Profile Box 3 sides 4 sides 3 sides 4 sides Dimensions to BS EN :1999 Size D x D Thickness t Mass per metre Area of Section mm mm Kg/m cm 2 m -1 m -1 m -1 m -1 m x x x x x Association for Specialist Fire Protection 29 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

30 Table 8: October 2006 Unequal Angles (UKA) Section factor A/V (Hp/A) Profile Box 3 sides 4 sides 3 sides 4 sides Dimensions to BS EN :1999 Designation Mass Area of Size Thickness per section D x B t metre mm mm kg cm 2 m -1 m -1 m -1 m -1 m -1 m -1 m -1 m -1 m -1 m x x x x x x x NB Data on older and other steel sections can be found on ASFP website/technical section Association for Specialist Fire Protection 30 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

31 Table 9: October 2006 Tees (UKT) Split from UK Beams Section factor A/V (Hp/A) Profile Box 3 sides 4 sides 3 sides 4 sides Dimensions to BS4 Part 1:2005 Serial size Mass per metre Width of section B Depth of section D Web thicknes s t Area of section mm kg mm mm mm cm 2 m -1 m -1 m -1 m -1 m -1 m x x x x x x x x x Association for Specialist Fire Protection 31 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

32 Table 9: October 2006 Tees (UKT) Split from UK Beams Section factor A/V (Hp/A) Profile Box 3 sides 4 sides 3 sides 4 sides Dimensions to BS4 Part 1:2005 Serial size Mass per metre Width of section B Depth of section D Web thicknes s t Area of section mm kg mm mm mm cm 2 m -1 m -1 m -1 m -1 m -1 m x x x x x x x x x x x NB Data on older and other steel sections can be found on ASFP website/technical section Association for Specialist Fire Protection 32 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

33 TABLE 10: October 2006 Structural Tees Split from UK Columns Dimensions to BS4 Part 1:2006 Serial size Mass per metre Width of section B Depth of section D Web thickness t Area of section Section factor A/V (Hp/A) Profile Box 3 sides 4 sides 3 sides 4 sides mm kg mm mm mm cm 2 m-1 m-1 m-1 m-1 m-1 m x x x x TABLE 11: July 06 ROLLED TEES NOTE: Whilst this ASFP publication has previously included listings for 4 sizes of rolled tees we are informed by Corus Construction & Industrial Division that rolled tees are no longer available from their current manufacturing facilities Association for Specialist Fire Protection 33 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

34 Table 12: October 2006 Circular Hollow Sections Dimensions to EN S355J2H Section factor A/V (Hp/A) Profile or box Table 13:Oct 06 Square Hollow Sections Dimensions to EN S355J2H Designation Section factor A/V (Hp/A) 3 sides 4 sides Wall Area of Size Wall Area of Outside Mass per Mass per thickness the D x D thickness the diameter metre metre t section a t section a mm mm Kg/m cm 2 m -1 mm mm Kg/m cm 2 m -1 m x x x x x x x table continued overleaf table continued overleaf Association for Specialist Fire Protection 34 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

35 Table 12: October 2006 Circular Hollow Sections Dimensions to EN S355J2H Section factor A/V (Hp/A) Profile or box Table 13:Oct 06 Square Hollow Sections Dimensions to EN S355J2H Designation Section factor A/V (Hp/A) 3 sides 4 sides Wall Area of Size Wall Area of Outside Mass per Mass per thickness the D x D thickness the diameter metre metre t section a t section a mm mm Kg/m cm 2 m -1 mm mm Kg/m cm 2 m -1 m x x x x x x x x table continued overleaf table continued overleaf Association for Specialist Fire Protection 35 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

36 Table 12: October 2006 Circular Hollow Sections Dimensions to EN S355J2H Section factor A/V (Hp/A) Profile or box Table 13:Oct 06 Square Hollow Sections Dimensions to EN S355J2H Designation Section factor A/V (Hp/A) 3 sides 4 sides Wall Area of Size Wall Area of Outside Mass per Mass per thickness the D x D thickness the diameter metre metre t section a t section a mm mm Kg/m cm 2 m -1 mm mm Kg/m cm 2 m -1 m x x x x x x x NB Data on older and other steel sections can be found on ASFP website/technical section Association for Specialist Fire Protection 36 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

37 Table 14: 2006 Rectangular Hollow Sections Section factor A/V (Hp/A) 3 sides 4 sides Dimensions to EN S355J2H Designation Area of the Mass per metre Size D x B Thickness t section mm mm Kg cm 2 m -1 m -1 m x x x x x x x Association for Specialist Fire Protection 37 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

38 Table 14: 2006 Rectangular Hollow Sections Section factor A/V (Hp/A) 3 sides 4 sides Dimensions to EN S355J2H Designation Area of the Mass per metre Size D x B Thickness t section mm mm Kg cm 2 m -1 m -1 m x x x x x x x x Association for Specialist Fire Protection 38 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

39 Table 14: 2006 Rectangular Hollow Sections Section factor A/V (Hp/A) 3 sides 4 sides Dimensions to EN S355J2H Designation Area of the Mass per metre Size D x B Thickness t section mm mm Kg cm 2 m -1 m -1 m x x x x x x x x x Association for Specialist Fire Protection 39 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

40 Table 14: 2006 Rectangular Hollow Sections Section factor A/V (Hp/A) 3 sides 4 sides Dimensions to EN S355J2H Designation Area of the Mass per metre Size D x B Thickness t section mm mm Kg cm 2 m -1 m -1 m x x x x x x x x x x Association for Specialist Fire Protection 40 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09

41 Table 14: 2006 Rectangular Hollow Sections Section factor A/V (Hp/A) 3 sides 4 sides Dimensions to EN S355J2H Designation Area of the Mass per metre Size D x B Thickness t section mm mm Kg cm 2 m -1 m -1 m NB Data on older and other steel sections can be found on ASFP website/technical section Association for Specialist Fire Protection 41 Fire protection for structural steel in buildings SECTION 1 4 th Edition revised 7 Oct 09