analysis of rc structures subjected to blast loading
TRANSCRIPT
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AnalysisAnalysis ofofReinforcedReinforced ConcreteConcreteStructuresStructures SubjectedSubjected toto BlastBlast LoadingLoading
S.S. KarapinarKarapinar, I ., I . SanriSanri, G. Altay, G. Altay
Workshop Prague, March 30Workshop Prague, March 30--31, 200731, 2007
COST Action C26COST Action C26
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AimAim ofof thethe StudyStudy
AnalyzeAnalyze thethe structuresstructures underunder thethe effectseffects ofof blastblastloadingloading..
IncludingIncluding
;;
thethe
threatthreat
definitiondefinition
,,
blastblast
wavewave
parametersparameters,, dynamicdynamic propertiesproperties ofof materialsmaterials andand
damagedamage assessmentassessment..
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Definition of Blast LoadingDefinition of Blast Loading
Blast loading may result from the detonation of highBlast loading may result from the detonation of highexplosives, chemical ammunitions.explosives, chemical ammunitions.
Type of extraordinary dynamic load and it has to beType of extraordinary dynamic load and it has to be
described by two parameters; peak overpressuredescribed by two parameters; peak overpressure
and duration.and duration.
Blast loading is a function of : Distance of theBlast loading is a function of : Distance of thestructure from the explosion, and the charge weightstructure from the explosion, and the charge weight
or a weapon size.or a weapon size.
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FormationFormation of aof a BlastBlast WaveWave
Variation of pressure within a shock wave (Variation of pressure within a shock wave (Fertis,1973, DynamicsAnd Vibration Of Structures)
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ThreatThreat DefinitionDefinition
Charge WeightCharge Weightororweapon size (W) :weapon size (W) :W is expressed in weight orW is expressed in weight ormass of TNTmass of TNT ; the equivalent W of any other explosive material is; the equivalent W of any other explosive material isbased on experimentally determined factors or the ratio of itsbased on experimentally determined factors or the ratio of itsheat of detonation to that of TNT.heat of detonation to that of TNT.
StandStand--offoffDistancesDistances(R) :(R) :R measures how close to the building aR measures how close to the building abomb could explode and is therefore a function of the physicalbomb could explode and is therefore a function of the physicalcharacteristics of the surrounding site.characteristics of the surrounding site.
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GeneralGeneral OverviewOverview ofof BlastBlast
LoadingLoading
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DynamicDynamic BehaviourBehaviour ofof MaterialMaterialUnderUnder BlastBlast LoadingLoading
WhenWhen thethe concreteconcrete isis strainedstrained;;
TheThe resistanceresistance increasesincreases linearlylinearly withwith deflectiondeflection untiluntil thethe
reinforcingreinforcing barsbars yieldyield..
TheThe deflectiondeflection isis increasingincreasing butbut thethe resistantresistant remainsremains constantconstant
untiluntil at aat a deflectiondeflection correspondingcorresponding toto aa supportsupport rotationrotation of 2of 2
At aAt a deflectiondeflection correspondingcorresponding toto aa valuevalue ofof aboutabout 44thethe
elementelement willwill loselose itsits structuralstructural integrityintegrity andand fail.fail.
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DynamicDynamic StrengthStrength IncreaseIncrease
Effects of strain rate on stressEffects of strain rate on stress--strain curve for concretestrain curve for concrete ((RefRef: TM 5: TM 5--1300)1300)
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DynamicDynamic IncreaseIncrease FactorFactor (DIF)(DIF)
DIF isDIF is
equalequal
toto
thethe
ratioratio
ofof
thethe
dynamicdynamic
materialmaterial
strengthstrength
toto
staticstatic
strengthstrength..
DIF is aDIF is a functionfunction of;of;
StaticStatic materialmaterial strengthstrength :: IfIf thethe staticstatic strengthstrength ofof materialmaterial isis highhigh
thenthen thethe increaseincrease inin dynamicdynamic strengthstrength willwill bebe lowlow..
StrainStrain rate :rate : IfIf thethe materialmaterial isis strainedstrained rapidlyrapidly thenthen thethe increaseincrease inindynamicdynamic strengthstrength willwill bebe highhigh..
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DeformationDeformation LimitsLimits
TheThe
controllingcontrolling
criteriacriteria
inin
thethe
blastblast
--resistantresistant
designdesign
is a limit onis a limit on
thethe deformationdeformation oror deflectiondeflection of element.of element.
TwoTwo methodsmethods forfor evaluationevaluation ofof structuralstructural responseresponse ::
DuctilityDuctility ratioratio
SupportSupport rotationrotation
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CaseCase StudyStudy
TheThe analysisanalysis ofof thethe structuralstructural elementselements underunder blastblastloadingloading withwith aa givengiven chargecharge weightweight andand standstand--offoff
distancedistance..
TheThe investigationinvestigation ofof thethe damageddamaged systemsystem whichwhich
containscontains thethe analysisanalysis ofof thethe systemsystem withwith membermember
removedremoved accordingaccording toto thethe explosionsexplosions..
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AnalysisAnalysis ofof StructureStructure underunder BlastBlastLoadingLoading
ChargeCharge weightsweights areare 500 kg , 750 kg , 1000 kg500 kg , 750 kg , 1000 kg andand
1500 kg of TNT.1500 kg of TNT.
StandStand--offoff distancedistance isis consideredconsidered as 6m.as 6m. whichwhich isis thethe
closestclosest pointpoint toto thethe buildingbuilding accordingaccording toto thethe planplan
configurationconfiguration ofof thethe buildingbuilding..
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Location of explosion to the buildingLocation of explosion to the building
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BlastBlast LoadLoad ParametersParameters
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BlastBlast
AnalysisAnalysis
ofof
StructuralStructural
FrameFrame
TheThe frameframe membersmembers onon whichwhich thethe planeplane isissubjectedsubjected toto explosionexplosion directlydirectly areare takentaken intointoconsiderationconsideration seperatelyseperately..
An elementAn element loadedloaded byby aa blastblast can becan be modeledmodeled as aas adynamicdynamic systemsystem withwith aa singlesingle degreedegree ofof freedomfreedomcorrespondigcorrespondig toto itsits midmid--spanspan deflectiondeflection..
TheThe responseresponse ofof thethe element iselement is determineddetermined usingusingABAQUS,ABAQUS, finitefinite element program,element program, whichwhich containscontainsgeometrygeometry andand materialmaterial nonnon--linearitylinearity..
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viewview ofof thethe xx--zz planeplane whichwhich isis subjectedsubjected directlydirectly totothethe explosionexplosion
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ModellingModelling ofof thethe ElementElement
Structural frames are modeled using solid, homogenousStructural frames are modeled using solid, homogenouselement.element.
Mesh design is a relatively fine mesh which providesMesh design is a relatively fine mesh which providesmoderate accuracy.moderate accuracy.
The material is concrete (YoungsThe material is concrete (Youngs modulmodulusus of 28500Mpa andof 28500Mpa andPoissons ratio of 0,2)Poissons ratio of 0,2)
The plasticity stressThe plasticity stress--strain curve is increased by the D.I.Fstrain curve is increased by the D.I.F
The pressureThe pressure--time load values are defined by applying to thetime load values are defined by applying to the
surface of thesurface of the element.element.
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BlastBlast AAnalysisnalysis ofof CColumnolumn SB121SB121 SSubjectedubjected
to 500kg of TNTto 500kg of TNT EExplosionxplosion
W=500 kg of TNT , R=6,16m.W=500 kg of TNT , R=6,16m. andand Z=0,78 (m/kgZ=0,78 (m/kg1/31/3))
PPsoso=1,54=1,54 MpaMpa
PPrr=9,405=9,405 MpaMpa
ttoo=0,008=0,008 secsec..
BlastBlast loadingloading ofof columncolumn SB121SB121
0
2
4
6
8
10
0 0,005 0,01
Time (sec.)
Averagepressu
re(Mpa)
Outside
pressure
inside
pressure
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AnalysisAnalysis ResultResult
MaxMax--stressstress distributiondistribution ColumnColumn midmid--pointpoint deflectiondeflection
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Damage AssessmentDamage Assessment
If the support rotation of the element is exceededIf the support rotation of the element is exceeded44, then it is said to be failed. By this way, three, then it is said to be failed. By this way, threemodels are considered with the member removedmodels are considered with the member removedaccording to the results are taken from theaccording to the results are taken from the AAbaqusbaqus
program.program.
The rest of the system is analyzed according to theThe rest of the system is analyzed according to thevertical loads by using SAP2000 package program.vertical loads by using SAP2000 package program.
TheThenn thethe capacities of the rest of the structuralcapacities of the rest of the structuralframes are checked to be the limitframes are checked to be the limit oror not.not.
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TheThe AnalysisAnalysis ofof thethe DamagedDamaged
SystemSystem
Model 1Model 1 duedue toto 750 kg of TNT750 kg of TNT
Model 2Model 2 duedue toto 1000 kg of TNT1000 kg of TNT
Model 3Model 3 duedue toto 1500kg of TNT1500kg of TNT
ThreeThree damagedamage scenariosscenarios areare preparedprepared..
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DamageDamage ScenariosScenarios
KB122, KZ16,KN116, KB123,KZ17, KB124,
KZ18, KN118,KB137, KZ31,KB142, KZ36,
KB149
SB120, SZ20,SB121, SZ21
Model 3
KB122, KZ16,
KB123, KB124,KZ18, KB137,KB142
SB121, SZ21,SB120Model 2
KB122, KB124,KZ18, KB142
SB121Model 1
Removed BeamsRemoved ColumnsDamagedScenario
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ModelModel 33 PP--M interaction of column SN121, SN221, SN321 inM interaction of column SN121, SN221, SN321 in
yy--directiondirection
-1500,00
-1000,00
-500,00
0,00
500,00
1000,00
1500,00
2000,00
2500,00
3000,00
3500,00
-800,00 -600,00 -400,00 -200,00 0,00 200,00 400,00 600,00
M (Knm)
P
(Kn)
P-M interactionP-M interaction
Balance LimitSN121SN221SN321
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SummarySummary ofof ResultsResults
KB 119, KB 138, KB141,KB143, KB121, KB120,
KZ25, KZ32, KZ35, KZ37,KZ15, KZ43, KN115,
KN125, KN132, KN135,KN137, KN143, KN217,KN218, KN225, KN235,KN237, KN238, KN325,KN335, KN337, KN343
SN120, SN220,SN320, SN121,SN221, SN321
KB122, KZ16,
KN116, KB123,KZ17, KB124,KZ18, KN118,KB137, KZ31,KB142, KZ36,
KB149
SB120, SZ20,SB121, SZ21
Model 3
KB 119, KB 138, KB141,KB143, KB121, KZ32,
KZ35, KZ37, KZ15,KN116, KN118, KN135,KN137, KN143, KN216,
KN218, KN235, KN237,KN238, KN316, KN317,KN318, KN335, KN337
SZ20, SN120,SN220, SN121,
SN221, SN321
KB122, KZ16,KB123, KB124,KZ18, KB137,
KB142
SB121, SZ21,SB120
Model 2
KB 119, KB 138, KB141SB120, SZ20,SZ21, SN121
KB122, KB124,KZ18, KB142SB121Model 1
Damaged BeamsDamagedColumns
RemovedBeams
RemovedColumns
DamagedScenario
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ConclusionConclusion
According to the results, the system affects significantly whenAccording to the results, the system affects significantly when thethe
charge weight increases. But the actual charge weight of explosicharge weight increases. But the actual charge weight of explosiveveused by the terrorist, the efficiency of the chemical reaction aused by the terrorist, the efficiency of the chemical reaction and thend thesource location are not reliably predictable.source location are not reliably predictable.
The standThe stand--off distance is the key parameter that determines theoff distance is the key parameter that determines the
blast pressure so for protecting a structure is to keep the bombblast pressure so for protecting a structure is to keep the bomb asasfar away as possible by maximizing the standfar away as possible by maximizing the stand--off distance.off distance.
Blast has a characteristic of high amplitude. The results showedBlast has a characteristic of high amplitude. The results showed thatthatif the member subjected to high pressure, they could cause bigif the member subjected to high pressure, they could cause bigdeformation on the element and cause to be exceed the supportdeformation on the element and cause to be exceed the supportrotation so the elements which are close to explosion are damagerotation so the elements which are close to explosion are damageddand failed.and failed.
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THANK YOU FORTHANK YOU FOR
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