欧洲建筑防火规范(Introduction-to-Eurocode-Structural-Fire-Engineering)课件

IntroductiontoEurocodeStructuralFireEngineeringStructuralSteelworkEurocodes1IntroductiontoEurocodeStrucStrain(%)0.51.01.52.0Stress(N/mm2)03002502001501005020°C200°C300°C400°C500°C600°C700°C800°CSteelsoftensprogressivelyfrom100-200°Cup.Only23%ofambient-temperaturestrengthremainsat700°C.

At800°Cstrengthreducedto11%andat900°Cto6%.Meltsatabout1500°C.Steelstress-straincurvesathightemperatures2Strain(%)0.51.01.52.0Stress(1.0012341000°C800°C20°C200°C400°C600°CStrain(%)NormalisedstressConcretealsolosesstrengthandstiffnessfrom100°Cupwards.Doesnotregainstrengthoncooling.

Hightemperaturepropertiesdependmainlyonaggregatetypeused.Concretestress-straincurvesathightemperatures31.0ThefiretriangleFuel+Oxidant=CombustionproductsCH4+O2=CO2+2H20ReactionoccurswhenOxygen/fuelmixturehotenoughHeatOxygenFuel4ThefiretriangleFuel+OxidanStagesofanaturalfire-andthestandardfiretestcurveCooling….ISO834standardfirecurveIgnition-SmoulderingPre-FlashoverHeatingPost-Flashover1000-1200°CNaturalfirecurveTimeTemperatureFlashover5Stagesofanaturalfire-andTheEC1(ISO834)standardfirecurve30010020004005006007008009001000060012001800240030003600Time(sec)GasTemperature(°C)5766757397818429456TheEC1(ISO834)standardfire200400600800100012000120024003600Time(sec)GasTemperature(°C)TypicalEC1ParametricfirecurveExternalFireStandardFireHydrocarbonFireFireresistancetimesbasedonstandardfurnacetests-NOTonsurvivalinrealfires.EC1ParametricFiretemperature-timecurves.Basedonfireloadandcompartmentproperties(<500m2).Onlyallowedwithcalculationmodels.DifferentEC1

time-temperaturecurves7200400600800100012000120024003CompartmentTemperatureLoad-bearingresistanceTimeTimeFireseveritytimeequivalentUsedtoratefireseverityorelementperformancerelativetofurnacetest.MatchestimestogiventemperatureinanaturalfireandinStandardFire.FireresistancetimeequivalentStandardfireNaturalfireElementTime-equivalence8CompartmentTemperatureLoad-beaFurnacetestsonstructuralelementsFireTesting

Loadkeptconstant,firetemperatureincreasedusingStandardFirecurve.Maximumdeflectioncriterionforfireresistanceofbeams.Loadcapacitycriterionforfireresistanceofcolumns.ProblemsLimitedrangeofspansfeasible,simplysupportedbeamsonly.Effectsofcontinuityignored.Beamsfailby“run-away”.Restrainttothermalexpansionbysurroundingstructureignored.9FurnacetestsonstructuralelStandardfireresistancefurnacetest1002003000120024003600Time(sec)Deflection(mm)10StandardfireresistancefurnaStandardfireresistancefurnacetest1002003000120024003600Time(sec)Deflection(mm)Span2/400dIfrate<span2/9000dStandardFireSpan/3011StandardfireresistancefurnaStructuralfireprotectionPassiveProtectionInsulatingBoardGypsum,Mineralfibre,Vermiculite.

Easytoapply,aestheticallyacceptable.Difficultieswithcomplexdetails.CementitiousSpraysMineralfibreorvermiculiteincementbinder.Cheaptoapply,butmessy;clean-upmaybeexpensive.Pooraesthetics;normallyusedbehindsuspendedceilings.IntumescentPaintsDecorativefinishundernormalconditions.

Expandsonheatingtoproduceinsulatinglayer.Cannowbedoneoff-site.12StructuralfireprotectionPass“Slim-floor”SystemsDownstandBeamShelf-angleBeamInherentfireprotectiontosteelbeams13“Slim-floor”SystemsDownstandStructuralfireprotection

CompositesectionsPassiveProtection–CompositesectionsDownstandBeamTraditionaldownstandbeamtopflangeupperfacetotallyshieldedbytheslab

14Structuralfireprotection

ComStructuralfireprotection

CompositesectionsPassiveProtection–CompositesectionsEncased

BeamBeamswithconcreteencasementHavehighfireresistance(upto180minutes).Involvecomplicatedconstructionofjoints.Requireformwork.15Structuralfireprotection

ComStructuralfireprotection

CompositesectionsPassiveProtection–CompositesectionsPartiallyEncasedBeamSteelbeamswithpartialconcreteencasementConcretebetweenflangesreducestherateofheatingoftheprofile'swebandupperflange.Concretebetweenflangescontributestotheload-bearingresistance.

Thebeamcanbefabricatedintheworkshopwithouttheuseofformwork.Simpleconstructionofjoints.16Structuralfireprotection

ComLoadreductionfactorinfireRelativetoambient-temperaturedesignresistanceEither…..Relativetoambient-temperaturedesignload(moreconservative)Ormoreusefully…..17LoadreductionfactorinfireREstablishingFireResistance:StrategiesEurocodesallowfireresistancetobeestablishedinanyof3“domains”:Time: tfi.d>tfi.requLoadresistance: Rfi.d.t>Efi.d.tTemperature: cr.d>

dUsuallyonlydirectlyfeasibleusingadvancedcalculationmodels.Feasiblebyhandcalculation.Findreducedresistanceatdesigntemperature.MostusualsimpleEC3method.Findcriticaltemperatureforloading,comparewithdesigntemperature.18EstablishingFireResistance:MaterialpropertiesSteelMechanical

(effectiveyieldstrength,elasticmodulus,...)ConcreteThermal

(thermalexpansion,thermalconductivity,specificheat)

Mechanical

(compressivestrength,secantmodulus,...)

Thermal

(thermalexpansion,thermalconductivity,specificheat)19MaterialpropertiesSteelMechaStrength/stiffnessreductionfactorsforelasticmodulusandyieldstrength(2%strain).Strain(%)0.51.01.52.0Stress(N/mm2)03002502001501005020°C200°C300°C400°C500°C600°C700°C800°CElasticmodulusat600°Creducedbyabout70%.Yieldstrengthat600°Creducedbyover50%.

Steelstress-straincurvesathightemperatures20Strength/stiffnessreductionfRftDegradationofsteelstrengthandstiffness0300600900120010080604020%ofnormalvalueTemperature(°C)RftEffectiveyieldstrength(at2%strain)SSElasticmodulusSSStrengthandstiffnessreductionsverysimilarforS235,S275,S355structuralsteelsandhot-rolledreinforcingbars.(SS)Cold-workedreinforcingbarsS500deterioratemorerapidly.(Rft)21RftDegradationofsteelstreng10050020040060080010001200Temperature(°C)654321Strain(%)Strength(%ofnormal)StrainatmaximumstrengthDegradationofconcretestrengthandstiffnessNormal-weightConcreteAccuratefornormaldensityconcretewithsiliceousaggregates.Conservativefornormaldensityconcretewithcalcareousaggregates,.LightweightConcreteConservativeforlight-weightconcretes.Alltypestreatedthesame.Strengthreductionfactors2210050020040060080010001200TempConcretestrengthinheatingandcoolingStress-strainrelationshipincoolingfrom700°C(at400C)Stress-strainrelationshipinheatingphase(700C)515250,010,020,03Stress-strainrelationshipatambienttemperatureStress-strainrelationshipinheatingphase(400C)Stress-strainrelationshipaftercoolingfrom700°C(at20C)23ConcretestrengthinheatingaThermalexpansionofsteelandconcrete00,51,01,52,02,53,03,54,04,5100200300400500600700800900Temperature(°C)ExpansionCoeff/°C(x10-6)SteelSteelthermalexpansionstopsduringcrystalstructrurechangeinthe700-800°Crange.Normal-weightconcreteConcreteunlikelytoreach700°Cintimeofabuildingfire.LightweightconcreteLight-weightconcretetreatedashavinguniformthermalexpansioncoefficient.24Thermalexpansionofsteelandla=45W/m°K(EC3simplecalculationmodel)Thermalconductivity(W/m°K)102030405060020040060080010001200Temperature(°C)Steelca=600J/kg°K(EC3simplecalculationmodel)OthersteelthermalpropertiesSpecificHeat(J/kg°K)5000020040060080010001200Temperature(°C)4000300020001000Steel25la=45W/m°K(EC3simplecalculaOtherconcretethermalpropertiesNCLCNCLCMayassumeconstantvalueforNC:1,60W/m.KMayassumeconstantvalueforNC:1000J/kg.Kcc*Specificheatcc(J/kg.K)400800100012002006001000°CThermalconductivitylc(W/m.K)2006001000°C12326OtherconcretethermalpropertThermalanalysisThermalanalysis:

bothEC3Part1.2andEC4Part1.2

unprotectedandprotectedsteelbeams

Lowerandupperflanges

Considerablydifferenttemperatures

propercalculationoftemperatures!Temperature

27ThermalanalysisThermalanalyTemperatureincreaseofunprotectedsteelTemperatureincreaseintimestepDt:Heatflux

hnet.d

has2parts:Radiation:Convection:SteeltemperatureSteelFiretemperature28TemperatureincreaseofunprotSectionfactorAm/V-unprotectedsteelmembersperimeterc/sareaexposedperimeterc/sareahb2(b+h)c/sarea90%!29SectionfactorAm/V-unprotecTemperatureincreaseofprotectedsteelSteeltemperatureSteelProtectionFiretemperaturedpSomeheatstoredinprotectionlayer.HeatstoredinprotectionlayerrelativetoheatstoredinsteelTemperatureriseofsteelintimeincrementDt30TemperatureincreaseofprotecexposedperimeterTotalc/sareaexposedplateTotalc/sareaexposedflangeTotalc/sareaSectionfactorAm/V-inherentlyprotectedsystems31exposedperimeterTotalc/sareSectionfactorAp/V-protectedsteelmembersSteelperimetersteelc/sareahb2(b+h)c/sareainnerperimeterofboardsteelc/sarea90%!32SectionfactorAp/V-protecte谢谢你的阅读知识就是财富丰富你的人生谢谢你的阅读知识就是财富IntroductiontoEurocodeStructuralFireEngineeringStructuralSteelworkEurocodes34IntroductiontoEurocodeStrucStrain(%)0.51.01.52.0Stress(N/mm2)03002502001501005020°C200°C300°C400°C500°C600°C700°C800°CSteelsoftensprogressivelyfrom100-200°Cup.Only23%ofambient-temperaturestrengthremainsat700°C.

At800°Cstrengthreducedto11%andat900°Cto6%.Meltsatabout1500°C.Steelstress-straincurvesathightemperatures35Strain(%)0.51.01.52.0Stress(1.0012341000°C800°C20°C200°C400°C600°CStrain(%)NormalisedstressConcretealsolosesstrengthandstiffnessfrom100°Cupwards.Doesnotregainstrengthoncooling.

Hightemperaturepropertiesdependmainlyonaggregatetypeused.Concretestress-straincurvesathightemperatures361.0ThefiretriangleFuel+Oxidant=CombustionproductsCH4+O2=CO2+2H20ReactionoccurswhenOxygen/fuelmixturehotenoughHeatOxygenFuel37ThefiretriangleFuel+OxidanStagesofanaturalfire-andthestandardfiretestcurveCooling….ISO834standardfirecurveIgnition-SmoulderingPre-FlashoverHeatingPost-Flashover1000-1200°CNaturalfirecurveTimeTemperatureFlashover38Stagesofanaturalfire-andTheEC1(ISO834)standardfirecurve30010020004005006007008009001000060012001800240030003600Time(sec)GasTemperature(°C)57667573978184294539TheEC1(ISO834)standardfire200400600800100012000120024003600Time(sec)GasTemperature(°C)TypicalEC1ParametricfirecurveExternalFireStandardFireHydrocarbonFireFireresistancetimesbasedonstandardfurnacetests-NOTonsurvivalinrealfires.EC1ParametricFiretemperature-timecurves.Basedonfireloadandcompartmentproperties(<500m2).Onlyallowedwithcalculationmodels.DifferentEC1

time-temperaturecurves40200400600800100012000120024003CompartmentTemperatureLoad-bearingresistanceTimeTimeFireseveritytimeequivalentUsedtoratefireseverityorelementperformancerelativetofurnacetest.MatchestimestogiventemperatureinanaturalfireandinStandardFire.FireresistancetimeequivalentStandardfireNaturalfireElementTime-equivalence41CompartmentTemperatureLoad-beaFurnacetestsonstructuralelementsFireTesting

Loadkeptconstant,firetemperatureincreasedusingStandardFirecurve.Maximumdeflectioncriterionforfireresistanceofbeams.Loadcapacitycriterionforfireresistanceofcolumns.ProblemsLimitedrangeofspansfeasible,simplysupportedbeamsonly.Effectsofcontinuityignored.Beamsfailby“run-away”.Restrainttothermalexpansionbysurroundingstructureignored.42FurnacetestsonstructuralelStandardfireresistancefurnacetest1002003000120024003600Time(sec)Deflection(mm)43StandardfireresistancefurnaStandardfireresistancefurnacetest1002003000120024003600Time(sec)Deflection(mm)Span2/400dIfrate<span2/9000dStandardFireSpan/3044StandardfireresistancefurnaStructuralfireprotectionPassiveProtectionInsulatingBoardGypsum,Mineralfibre,Vermiculite.

Easytoapply,aestheticallyacceptable.Difficultieswithcomplexdetails.CementitiousSpraysMineralfibreorvermiculiteincementbinder.Cheaptoapply,butmessy;clean-upmaybeexpensive.Pooraesthetics;normallyusedbehindsuspendedceilings.IntumescentPaintsDecorativefinishundernormalconditions.

Expandsonheatingtoproduceinsulatinglayer.Cannowbedoneoff-site.45StructuralfireprotectionPass“Slim-floor”SystemsDownstandBeamShelf-angleBeamInherentfireprotectiontosteelbeams46“Slim-floor”SystemsDownstandStructuralfireprotection

CompositesectionsPassiveProtection–CompositesectionsDownstandBeamTraditionaldownstandbeamtopflangeupperfacetotallyshieldedbytheslab

47Structuralfireprotection

ComStructuralfireprotection

CompositesectionsPassiveProtection–CompositesectionsEncased

BeamBeamswithconcreteencasementHavehighfireresistance(upto180minutes).Involvecomplicatedconstructionofjoints.Requireformwork.48Structuralfireprotection

ComStructuralfireprotection

CompositesectionsPassiveProtection–CompositesectionsPartiallyEncasedBeamSteelbeamswithpartialconcreteencasementConcretebetweenflangesreducestherateofheatingoftheprofile'swebandupperflange.Concretebetweenflangescontributestotheload-bearingresistance.

Thebeamcanbefabricatedintheworkshopwithouttheuseofformwork.Simpleconstructionofjoints.49Structuralfireprotection

ComLoadreductionfactorinfireRelativetoambient-temperaturedesignresistanceEither…..Relativetoambient-temperaturedesignload(moreconservative)Ormoreusefully…..50LoadreductionfactorinfireREstablishingFireResistance:StrategiesEurocodesallowfireresistancetobeestablishedinanyof3“domains”:Time: tfi.d>tfi.requLoadresistance: Rfi.d.t>Efi.d.tTemperature: cr.d>

dUsuallyonlydirectlyfeasibleusingadvancedcalculationmodels.Feasiblebyhandcalculation.Findreducedresistanceatdesigntemperature.MostusualsimpleEC3method.Findcriticaltemperatureforloading,comparewithdesigntemperature.51EstablishingFireResistance:MaterialpropertiesSteelMechanical

(effectiveyieldstrength,elasticmodulus,...)ConcreteThermal

(thermalexpansion,thermalconductivity,specificheat)

Mechanical

(compressivestrength,secantmodulus,...)

Thermal

(thermalexpansion,thermalconductivity,specificheat)52MaterialpropertiesSteelMechaStrength/stiffnessreductionfactorsforelasticmodulusandyieldstrength(2%strain).Strain(%)0.51.01.52.0Stress(N/mm2)03002502001501005020°C200°C300°C400°C500°C600°C700°C800°CElasticmodulusat600°Creducedbyabout70%.Yieldstrengthat600°Creducedbyover50%.

Steelstress-straincurvesathightemperatures53Strength/stiffnessreductionfRftDegradationofsteelstrengthandstiffness0300600900120010080604020%ofnormalvalueTemperature(°C)RftEffectiveyieldstrength(at2%strain)SSElasticmodulusSSStrengthandstiffnessreductionsverysimilarforS235,S275,S355structuralsteelsandhot-rolledreinforcingbars.(SS)Cold-workedreinforcingbarsS500deterioratemorerapidly.(Rft)54RftDegradationofsteelstreng10050020040060080010001200Temperature(°C)654321Strain(%)Strength(%ofnormal)StrainatmaximumstrengthDegradationofconcretestrengthandstiffnessNormal-weightConcreteAccuratefornormaldensityconcretewithsiliceousaggregates.Conservativefornormaldensityconcretewithcalcareousaggregates,.LightweightConcreteConservativeforlight-weightconcretes.Alltypestreatedthesame.Strengthreductionfactors5510050020040060080010001200TempConcretestrengthinheatingandcoolingStress-strainrelationshipincoolingfrom700°C(at400C)Stress-strainrelationshipinheatingphase(700C)515250,010,020,03Stress-strainrelationshipatambienttemperatureStress-strainrelationshipinheatingphase(400C)Stress-strainrelationshipaftercoolingfrom700°C(at20C)56ConcretestrengthinheatingaThermalexpansionofsteelandconcrete00,51,01,52,02,53,03,54,04,5100200300400500600700800900Temperature(°C)ExpansionCoeff/°C(x10-6)SteelSteelthermalexpansionstopsduringcrystalstructrurechangeinthe700-800°Crange.Normal-weightconcreteConcreteunlikelytoreach700°Cintimeofabuildingfire.LightweightconcreteLight-weightconcretetreatedashavinguniformthermalexpansioncoefficient.57Thermalexpansio