Analysis of RC Structures Subjected to Blast Loading

8/9/2019 Analysis of RC Structures Subjected to Blast Loading

1/26

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


2/26

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..


3/26

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.


4/26

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)


5/26

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.


6/26

GeneralGeneral OverviewOverview ofof BlastBlast

LoadingLoading


7/26

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.


8/26

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)


9/26

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..


10/26

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


11/26

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..


12/26

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..


13/26

Location of explosion to the buildingLocation of explosion to the building


14/26

BlastBlast LoadLoad ParametersParameters


15/26

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..


16/26

viewview ofof thethe xx--zz planeplane whichwhich isis subjectedsubjected directlydirectly totothethe explosionexplosion


17/26

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.


18/26

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


19/26

AnalysisAnalysis ResultResult

MaxMax--stressstress distributiondistribution ColumnColumn midmid--pointpoint deflectiondeflection


20/26

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.


21/26

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..


22/26

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


23/26

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


24/26

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


25/26

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.


26/26

THANK YOU FORTHANK YOU FOR

YOUR ATTENTIONYOUR ATTENTION

Documents

Analysis of RC Structures Subjected to Blast Loading