Structural fire engineering design:materials behaviour – steel

C Bailey BEng PhD CEng MIStructE MIFireE

UMIST

Digest 487Part 2

This Digest is part of a suite of related documents containing guidance for the construction industry on structural fire engineering design. Theintention is to produce performance based guidance that brings together fire engineering and structural engineering providing aframework within which designers are free to develop site specificsolutions based on real performance criteria. The Digests containinformation complementary to the existing and emerging fire engineering codes and standards. Each Digest may be used in isolation or as part of the full integrated suite.Owing to its high thermal conductivity exposed steel will increase intemperature very quickly during a fire, losing strength and stiffness. The designer must ensure that any building will maintain its stability for a reasonable period should any accidental fire occur. This Digest presents the current available design tools to ensure stability of steelframed buildings during a fire.

dige

st

For the safety of the occupants, firefighters andpeople in the proximity of a building, the designermust ensure that if a fire occurs the building willnot collapse for a reasonable period. To achievethis aim for steel framed buildings, the mostcommon approach adopted by designers is toprovide fire resistance to each steel member asstated in the Approved Document B[1]. The fireresistance of members can be achieved by:● applying some form of fire protection, currently

the most common approach adopted in the UK;● using current codes to design individual

members at the fire limit-state which takes intoaccount realistic load levels at the time of thefire, realistic temperature distributions boththrough the cross-section and along the lengthof members, together with actual materialresponse at elevated temperatures;

● using the numerous available fire design guideswhich employ forms of construction wheresteel is provided with partial protection byconcrete or masonry;

● applying sophisticated finite-element models.

There is no need for the designer to ensure the fireresistance of each steel member in the building if itcan be shown by other means that the building willmaintain its stability for a reasonable period. Forconstruction using typical downstand steel beamsand composite floor slabs, a new design approachmay be used where the fire resistance of the wholefloorplate, instead of individual members, isassessed. The designer could also use natural fires(defined by the amount of combustible material,ventilation and the characteristics of compartmentboundaries) to determine the time–temperatureresponse for a given fire compartment. A thermalanalysis is then conducted to assess thetemperature distribution through the structurefollowed by a structural analysis.

The design tools now available to ensure thatsteel framed buildings maintain their stability for areasonable time are described in the pages thatfollow, with their advantages and disadvantagessummarised at the end of each section. Theimportance of maintaining the integrity of steelmember-to-member connections is also discussed.

Lice

nsed

Cop

y: m

pp, M

icha

el P

unch

& P

artn

ers

Ltd,

12/

11/2

007

09:2

7:08

, Unc

ontr

olle

d C

opy,

© IH

S B

RE

Pre

ss

Generic and proprietary fire protection materialsThe traditional, and still the most common, method ofensuring fire resistance for steel structures is to protectexposed steel members using various generic or proprietaryfire protection systems. For generic protection materialscomprising concrete, brick and blockwork, gypsum plasterand certain types of plasterboard, guidance is given in theBRE publication Guidelines for the construction of fireresisting structural elements[2]. For proprietary materialscomprising sprays, boards and intumescent coatings,guidance is obtained directly from the manufacturer or fromthe publication Fire protection for structural steel inbuildings[3] (commonly referred to as the Yellow Book).

The main advantage of using generic or proprietaryprotection systems is that the calculation effort required bythe designer is nominal. For a given steel framed building, thedesigner concentrates on the ultimate and serviceabilitylimit-states, together with buildability, and generally ignoresthe actual structural behaviour of the building due to apossible fire. To provide the required fire resistance to a steelmember the designer uses standard tables, for the chosenprotection system, and simply specifies a protectionthickness based on the steel section size, shape and requiredfire resistance.

Experience has shown that protection systems, which aresufficiently maintained and remain in place during a fire, willperform adequately with the protected steel retainingsufficient strength and stiffness in a fire. However, due to thematerial cost – and possibly more importantly theconstruction time (with the task of fixing protection typicallybeing on the critical path of the construction programme) –the steel industry, together with a number of researchorganisations, have developed alternative methods ofachieving fire resistance which reduce or eliminate the use ofapplied fire protection systems.

Although the prescriptive approach of specifyingprotection systems has generally been shown to be adequate,it is known that the approach is typically conservative. Forproprietary sprays and boards the thickness is generallyspecified on the basis that the steel will not exceed 550 °C fora given section size, shape and fire resistance period. At atemperature of 550 °C it is assumed that steel’s ambientdesign safety margin is removed, which is a reasonableassumption provided the steel member is uniformly heated,fully stressed at ambient temperature and acts as an isolatedmember when forming part of a whole building. If non-uniform heating, realistic load levels and actual structuralbehaviour are considered, failure temperatures significantlyhigher than 550 °C can be obtained.

For some protection types, the recent edition of the YellowBook does provide separate thicknesses for columns andbeams supporting concrete floor slabs. Due to the non-uniform heating caused by the heat-sink effect of thesupported slab, the protection thickness for beams is based onensuring that the steel does not exceed a maximumtemperature of 620 °C for a given section size, shape and fireresistance period. However, the specified protection stillignores the fact that members are generally not fully stressedat ambient temperature and their real behaviour in a wholestructure is significantly different from the memberbehaviour assumed.

A distinct advantage of intumescent coatings is that theycan readily be applied to the steel members prior to deliveryto site, with the connections between members beingprotected following erection[4]. The approach of applying theprotection off-site can be beneficial in reducing theconstruction time and enhancing the quality of application ofthe protection. However, care should be taken to ensuredamage to the protection does not occur during the storage,transportation or erection stages. It is also possible to applyspray protection off-site, though it can be difficult to ensurethat damage to the protection does not occur prior to, orduring, construction.

The advantages and disadvantages of using generic andproprietary protection materials are shown in Table 1.

2

Table 1 Use of generic and proprietary protection materials

Advantages● Limited design effort required● Investigation of real fires, over an extended period of time, has

shown the approach to be adequate● Approach is easily understood by designers and Checking

Authorities● Intumescent coatings can be easily applied off-site resulting in

reduced construction time

Disadvantages● Generally a conservative approach resulting in the use of material

that is not required● Fixing of protection material generally lies on the critical path of the

construction programme● Design approach ignores the actual behaviour of a building in a fire● Some protection materials are susceptible to impact damage● Some protection systems are easily damaged by the maintenance

and upgrading of buildings

Lice

nsed

Cop

y: m

pp, M

icha

el P

unch

& P

artn

ers

Ltd,

12/

11/2

007

09:2

7:08

, Unc

ontr

olle

d C

opy,

© IH

S B

RE

Pre

ss

Structural steel and composite design codesThe fire design codes BS 5950-8[5], Eurocode 3 Part 1-2[6] andEurocode 4 Part 1-2[7] provide the framework for designers tocalculate the temperature at which a given steel member willfail in a fire situation. These design methods incorporatemore realistic estimates of the applied load during a fire andinclude the effects of non-uniform heating through and alongthe member. The design methods are based on either fireresistance, which is a measure of an element to withstandgiven criteria in a standard furnace test, or natural fires wherethe size of the fire compartment, available combustiblematerial, characteristics of the compartment boundaries andair supply are considered.

It seems that the practical use of the codified methods toreduce or eliminate the use of applied fire protection has beenlimited, which could be attributed to the following.

● For designs of typical downstand beams and H-columns,based on the concept of fire resistance, it is only possible toachieve 30 minutes fire resistance for totally unprotectedsteel if the steel structure is typically over-designed atambient temperature.

● Using natural fires, instead of fire resistance, iscomplicated and a new concept to most designers. Atpresent only specialised designers take advantage of thisdesign method.

● Owing to the reduced margins on the cost of design work,designers are reluctant to include extra design work withintheir programmes of work.

● The suppliers of proprietary protection materials havebeen reluctant to issue thermal characteristics for theirproducts, which allow the protection thicknesses to bereduced from current values by basing requiredthicknesses on the actual failure temperature of members.

Although using the codified methods has been limited bydesigners, the steel industry, notably the Steel ConstructionInstitute (SCI), has used the basic principles set out in thecodes to promote forms of construction that offer sufficientpartial protection to the steel structure. These developedconstruction systems eliminate the need to supply and fixtypical proprietary fire protection systems. Typical forms ofconstruction are described on page 4.

The advantages and disadvantages of using the currentdesign codes are summarised in Table 2.

3

Table 2 Use of design codes

Advantages● Steel members can be designed without the need for applied fire

protection● Allows the thickness of generic and proprietary protection materials

to be reduced compared to values specified which are based on the typical 550/620 °C failure temperature

● Allows systems that utilise partial protection to be assessed● Allows the use of natural fires in the assessment of structural

behaviour

Disadvantages● Using unprotected steel members generally results in the need

to specify larger sections compared to those required to satisfy serviceability and ultimate limit-states

● Only 30 minutes fire resistance can be achieved for totally unprotected steel members

● Requires more design effort compared to using simple look-up tables associated with the conservative application of generic and proprietary protection materials

● The thermal characteristics of proprietary protection materials which are required to reduce their thickness are not readily available from manufacturers

Lice

nsed

Cop

y: m

pp, M

icha

el P

unch

& P

artn

ers

Ltd,

12/

11/2

007

09:2

7:08

, Unc

ontr

olle

d C

opy,

© IH

S B

RE

Pre

ss

Structural members using partial protectionIt is possible to adopt forms of construction which eliminatethe need for additional passive fire protection[8]. The commonforms of beams, columns and floors that utilise partialprotection are described below.

BeamsBy placing a significant portion of the beam within the depthof the supported concrete slab it is possible to specify steelbeams without the need to apply additional fire protection.For typical downstand I-beams, the floor slab can besupported by shelf-angles with the legs of the angles pointingupwards into the slab – a form of construction commonlyreferred to as shelf-angle beams (Figure 1). The part of thesteel section and supporting angles embodied in thesupporting slab can allow 30 minutes fire resistance to bereadily obtained for this type of member. It is possible toincrease the fire resistance to 60 minutes although therequired thickness of concrete slab may make this form ofconstruction uneconomical.

Some systems, known as slim-floor beams, areconstructed such that the beam is encased in the supportingconcrete slab with only the bottom flange or plate exposed toany fire (Figure 1). SCI and Corus have promoted systemsknown as Slimflor® and Slimdek® where beams can readilyachieve 60 minutes fire resistance without the need to protectthe exposed bottom flange or plate. Another form of slim-floor beam is the Deltabeam, marketed by BRC ConcreteConnections, which can readily achieve two hours fireresistance. The systems available on the UK market havetheir own advantages and disadvantages, and it is difficult toprovide generalised information on the choice of the bestsystem. The use of the systems should be assessed on aproject-by-project basis.

Another form of construction, where the beam is partiallyprotected by concrete, consists of filling the area between theflanges and web with reinforced concrete (Figure 1). Thistype of construction is popular in continental Europe wherethe cost of proprietary fire protection materials is relativelyhigh. The system can readily achieve two hours fireresistance and has the advantage of being resistant to impactdamage, although the increase in self-weight of the structurecan be seen as a disadvantage when designing thefoundations.

4

Figure 1 Forms of beams with partial protection

•••

•

• •

•

In situ concrete

Precast floor unit Shelf-angle

Mesh reinforcement

Deep composite floor slab or precast unit

Assymmetric ‘rolled’ beamProfiled metaldeck

Precast floor unit or deep composite floor slab

Additional reinforcement to achieve fire resistance

Bottom plate

Reinforcing bar

Link welded to web

Shelf-angle beam

Asymmetrical slim-floor beam

Deltabeam

Partially encased beam

Lice

nsed

Cop

y: m

pp, M

icha

el P

unch

& P

artn

ers

Ltd,

12/

11/2

007

09:2

7:08

, Unc

ontr

olle

d C

opy,

© IH

S B

RE

Pre

ss

ColumnsAs with steel beams it is possible to enhance the fireresistance of steel columns by adopting systems whereconcrete and masonry materials provide sufficient, althoughpartial, protection. A simple method is to place aeratedconcrete blocks between the inner faces of the flanges(Figure 2). For columns, of size 203 x 203 x 46 UC andgreater, 30 minutes fire resistance can be achieved. Anothermethod, developed by SCI[8], involves filling between theflanges with unreinforced concrete. Welded plates and shearfixings allow the load to be transferred from the steel sectionto the concrete during a fire. This system can achieve60 minutes fire resistance and can resist impact damage. Avariation of the SCI infill column is to provide reinforcementto the infill concrete (Figure 2). Similar to the infill beams,this system is popular in continental Europe and can achievetwo hours fire resistance.

The most common form of steel column that generallydoes not use applied proprietary fire protection materials isthe concrete-filled hollow steel section (Figure 2). The infillconcrete may be unreinforced or reinforced depending on therequired load capacity and fire resistance. For reinforcedconcrete infill columns, two hours fire resistance can beeasily obtained. To achieve the most efficient concrete-filledcolumn, in terms of fire resistance, the section should bedesigned in the cold state so that the load carrying capacity ofthe steel shell is low compared to the load carrying capacityof the concrete core.

FloorsComposite floor slabs – comprising profiled steel deck,concrete and mesh reinforcement – have been shown to havea good, inherent fire resistance. Standard fire tests, to definefire resistance periods, have shown that two hours fireresistance can be obtained with the underside of the steeldeck left exposed to the fire. Most composite floor slabs, usedin the UK, are designed using the Simplified Methoddeveloped by SCI[8]. This method is usually presented inmanufacturers’ design tables which are typically applied bydesigners. However, it is important to emphasise that themethod is only valid for slabs that are continuous over at leastone span and the mesh reinforcement must be placed within aspecified depth range. The Fire Engineering method, alsodeveloped by SCI, can be used to design composite floors toresist fire. The method consists of placing additionalreinforcement bars within the ribs of the slab and over thesupports. The temperature through the cross-section of theslab is determined, followed by a plastic analysis usingreduced material properties. Any contribution from the steeldeck is ignored.

The advantages and disadvantages of using systems thatuse partial protection are summarised in Table 3.

5

Figure 2 Forms of columns with partial protection

Table 3 Structural members using partial protection

Advantages● Most typical structural forms are covered by simple design

guidance● Structural members are generally robust and have significant

resistance to impact damage● Maintenance and upgrading of building services will (generally) not

cause damage which reduces fire resistance● The construction time is generally reduced compared to using

applied fire protection

Disadvantages● Some knowledge of the fire design codes is required to calculate

loads and moments at the fire limit-state● Design guidance is currently limited to fire resistance periods and

natural fires cannot be easily applied● Structural members are difficult to design from first principles

without using accurate thermal and mechanical models● The concrete used in some of structural forms increases the

deadweight of the structure● Connections between different structural forms may be difficult and

costly

Aerated concrete blocks(minimum density 475 kg/m3)

Partially encasedcolumn

Concrete-filled, hollow steel-section column

Blocked-in concretecolumn

Reinforcing bar

•

•••

• •

• •

•

• •

•Reinforcing bar

Link welded to web

Lice

nsed

Cop

y: m

pp, M

icha

el P

unch

& P

artn

ers

Ltd,

12/

11/2

007

09:2

7:08

, Unc

ontr

olle

d C

opy,

© IH

S B

RE

Pre

ss

Design of composite floorplatesFrom the results of fire tests carried out on the eight-storeyfull-scale, steel framed building at the BRE laboratories inCardington, together with research into the behaviour ofconcrete and composite floors slabs at large displacements, anew fire design method has been developed. The method canbe only applied to designs for buildings with composite floorslabs supported by downsand steel beams. By applying themethod, where the fire resistance of the floor slab andsupporting steel beams is considered in its entirety, it ispossible for a significant number of beams, within a givenfloorplate, to be left unprotected for any specified fireresistance period. The design method is presented in easy touse tables in a design guide published by the SCI[9]. Due tothe requirement of presenting the method in design tables,some limitations are imposed in the guide. However, themethod can be used to its full potential by adopting theprocedures outlined in Digest 462[10]. At present the methodis limited to fire resistance periods. In the near future it isanticipated that the method will be extended so that natural(parametric) fires can be used.

The advantages and disadvantages of using the new designmethod for composite floorplates are summarised in Table 4.

Using finite-element modelsSophisticated finite-element computer models can be used topredict the structural response of steel members, sub-frames,or entire buildings. The application of these models iscomplex and should only be used by competent designerswho fully understand both the limitations and capabilities ofthe models.

Due to the complex nature of these models it is difficult forChecking Authorities to understand and approve designswhich rely heavily on the results from the models. If complexfinite-element models are used, careful consideration shouldbe given to:1 the adopted failure criteria and the consequences on the

overall fire engineering strategy;2 consideration of the localised behaviour, especially the

fracture of steel reinforcement and robustness ofconnections;

3 validation of the model;4 boundary conditions and assumptions of lines of

symmetry for sub-frames;5 interpretation of the results;6 the adopted heating regime. If natural fires are considered,

a range of feasible fire scenarios should be considered.

The above list should be considered only as a minimumrequirement and further checks could be required dependingon the type of building being considered.

The advantages and disadvantages of using finite-elementmodels are summarised in Table 5.

6

Table 4 Composite floorplates

Advantages● 40–50% of steel beams within a given floorplate can be left

unprotected● Material cost and construction time are reduced● Problems with damage to protection systems are reduced● The design method is based on fundamental engineering principles

which can be easily checked and assessed

Disadvantages● Mesh reinforcement typically needs to be increased in size

compared to systems where all beams are protected● The SCI guide is simple to use but imposes limitations● Digest 462 allows the method to be used to its full potential but

requires more design effort● A new concept which requires educating both designers and

Checking Authorities before it becomes widely accepted

Table 5 Finite-element models

Advantages● Generally results in an overall reduction of applied fire protection● Provides an understanding of the true behaviour of the whole

building● Allows the displacement of the structure to be predicted throughout

the full duration of a fire

Disadvantages● These models are seen as ‘black boxes’ making checking of

designs difficult● Most models are still not able to predict localised fracture of

reinforcement in slabs● The use and application of the models can be expensive● Large scale tests (required to provide validation) are limited

Lice

nsed

Cop

y: m

pp, M

icha

el P

unch

& P

artn

ers

Ltd,

12/

11/2

007

09:2

7:08

, Unc

ontr

olle

d C

opy,

© IH

S B

RE

Pre

ss

ConnectionsFor simplicity, most multi-storey, steel framed buildings inthe UK are designed assuming that the connectionseffectively transfer no moment between connected members,with lateral loads resisted by shear walls or bracing. It is,however, well known that even so-called ‘simple’connections transfer some moment. In a fire where largedisplacements are acceptable, the rotational restraintprovided by simple connections can assist with the survivalof the beams. Recognising the beneficial effect of therotational restraint of connections, which is ignored in thecold design, the SCI has published design guidance[11] whichallows designers to include the rotational restraint of theconnection when assessing the fire resistance of the steelbeams. This guidance was based on 12 small-scale testscarried out on various connections using standard, small-scale cruciform frames.

Following observations of the Cardington fire tests, it isgenerally considered that the SCI guidance is unconservativefor exposed downstand beams supporting a composite floorslab and should not be used. The Cardington tests showedthat local buckling typically occurred in the lower flange ofthe beam in the proximity of the connection. The localbuckling was caused by the high compressive forces inducedinto the heated beam from restraint to thermal expansionprovided by the surrounding cold structure and the negativemoment induced into the connection by the increasedcurvature of the heated beam. The induction of local bucklingdue to restraint of thermal expansion did not occur in the 12small-scale tests (which formed the basis of the SCI designguide on connections) since the heated beams where free toexpand. As it is difficult to assess the transfer of momentacross the local buckle and into the connection under thecombined load of axial force and negative moment, aconservative and recommended design approach is to assumethat the connections are ‘pinned’ in the fire situation.

Another observation of connection behaviour from theCardington fire tests was the fracture down one side of theplate of the partial depth, end-plate connections (Figure 3)and shear of the bolts in the fin-plate connections. Thisbehaviour was attributed to the high tensile forces inducedinto the steel beams as they cooled down from an inelasticstate reached during heating. Consideration in the choice ofconnection is needed to ensure stability during the coolingphase of the fire. End-plate types of connections havegenerally shown that vertical shear capacity is maintained.For fin-plate connections, the consequence of bolt shear,during cooling, should be considered. Vertical support can bemaintained if either the top flange of the beam is supported bythe fin-plate or the supporting composite slab can provide therequired vertical shear. Web cleat connections are consideredto be sufficiently ductile to maintain vertical support underlarge tensile forces in the beam[9].

7

Figure 3 Fracture of end-plate type of connection during cooling

Typical fracture in

end-plate occurring

during cooling

Shear capacity of

connection maintained by

unfractured side of plate

Tensile force induced

during cooling

Design approaches

This Digest discusses the various approaches, available todesigners, for achieving the required fire resistance for members andcomposite floor plates. The use of natural fires in the application ofdesign codes and finite-element models has briefly been discussed.

The design method chosen for ensuring fire resistance, or thedecision to use natural fires, will be based on the willingness of thedesigner to carry out the required design calculations and thepotential overall cost saving associated with carrying out thesecalculations. The calculation effort increases once the designermoves away from the conservative prescriptive approach of applyinggeneric and proprietary protection materials and is perhaps theprimary reason why this method of achieving fire resistance is still themost common. It is difficult to provide an indication of the potentialcost savings that can be achieved by adopting an alternative method,instead of the common approach of applying fire protection, sincethis can only realistically be assessed on a project-by-project basis.

Lice

nsed

Cop

y: m

pp, M

icha

el P

unch

& P

artn

ers

Ltd,

12/

11/2

007

09:2

7:08

, Unc

ontr

olle

d C

opy,

© IH

S B

RE

Pre

ss

8

BRE is committed to providingimpartial and authoritative informationon all aspects of the built environmentfor clients, designers, contractors,engineers, manufacturers, occupants,etc. We make every effort to ensurethe accuracy and quality of informationand guidance when it is first published.However, we can take no responsibilityfor the subsequent use of thisinformation, nor for any errors oromissions it may contain.

BRE is the UK’s leading centre ofexpertise on building and construction,and the prevention and control of fire.Contact BRE for information about itsservices, or for technical advice, at:BRE, Garston, Watford WD25 9XXTel: 01923 664000Fax: 01923 664098email: enquiries@bre.co.ukWebsite: www.bre.co.uk

Details of BRE publications are availablefrom:www.brebookshop.comorIHS Rapidoc (BRE Bookshop)Willoughby RoadBracknell RG12 8DWTel: 01344 404407Fax: 01344 714440email: brebookshop@ihsrapidoc.com

Published by BRE Bookshop Requests to copy any part of thispublication should be made to:BRE Bookshop, Building Research Establishment,Watford WD25 9XXTel: 01923 664761Fax: 01923 662477email: brebookshop@emap.com

© Copyright BRE 2004June 2004ISBN 1 86081 699 1

www.bre.co.uk

References

[1] Department of the Environment and the Welsh Office. The Building Regulations 2000 ApprovedDocument B: Fire Safety (2000 edn). London, The Stationery Office.

[2] Morris W A, Read R E H and Cooke G M E. Guidelines for the construction of fire-resisting structuralelements. BRE Report 128. Garston, BRE Bookshop, 1988.

[3] Association for Specialist Fire Protection and The Steel Construction Institute. Fire protection forstructural steel in buildings (3rd edition). Ascot, SCI, 2002.

[4] Yandzio E, Dowling J J, and Newman G M. Structural fire design. Off-site applied thin film intumescentcoatings. Steel Construction Institute publication P160. Ascot, SCI, 1996.

[5] British Standards Institution. Structural use of steelwork in buildings. Code of practice for fire resistantdesign. British Standard BS 5950-8:2003. London, BSI, 2003.

[6] European Committee for Standardisation. Eurocode 3. Design of steel structures. General rules.Structural fire design. prEN 1993-1-2:2002.

[7] European Committee for Standardisation. Eurocode 4. Design of composite steel and concretestructures. General rules. Structural fire design. prEN 1994-1-2:2002.

[8] Bailey C G, Newman G M and Simms W I. Design of steel framed buildings without applied fire protection.Steel Construction Institute publication P186. Ascot, SCI, 1999.

[9] Newman G M, Robinson J T and Bailey C G. Fire safe design. A new approach to multi-storey steel-framedbuildings. Steel Construction Institute publication P288. Ascot, SCI, 2000.

[10] Bailey C. Steel structures supporting composite floor slabs: design for fire. BRE Digest 462. Garston, BRE,2001.

[11] Lawson R M. Enhancement of fire resistance of beams by beam to column connections. Steel ConstructionInstitute publication P086. Ascot, SCI, 1990.

Acknowledgement

This Digest has been produced with the support of the Office of theDeputy Prime Minister

Other BRE and FBE publications concerned with fire engineering and fire designDigest 462 Steel structures supporting composite floor slabs: design for fireBR 128 Guidelines for the construction of fire-resisting structural elementsBR 135 Fire performance of external thermal insulation for walls of multi-storey buildings

(2nd edition)BR 368 Design methodologies for smoke and heat exhaust ventilationBR 459 Fire safety engineering. A reference guideFB 5 New fire design method for steel frames with composite floor slabs

Lice

nsed

Cop

y: m

pp, M

icha

el P

unch

& P

artn

ers

Ltd,

12/

11/2

007

09:2

7:08

, Unc

ontr

olle

d C

opy,

© IH

S B

RE

Pre

ss