SHM details 2

8/21/2019 SHM details 2

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STRUCTURALHEALTHMONITORING

dr.ing.NAGYGYRGY Tams

lecturer2012v1


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REFERENCES

. . SAMCO http://www.samco.org/network/index.htm ISIS and SAMCO Educational Module 5: An Introduction to Structural Health


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INTRODUCTION WhyweneedSHM?

Populationdependsonanextensiveinfrastructuresystem

roads

buildingsetc

Theinfrastructuresystemhassuffered

neglect eter orat onlackoffunding

ISIS Canada Educational Module 5


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Factorsleadingtotheextensivedegradation

existinginfrastructure

Consequences: Problemsbecomeapparentonlywhenstructuresareindireneedofrepair

Result Repaircostsbecomecomparableto

replacementcosts



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reinforcementwithinconcrete

Consequences: Expansionofsteelleadstocrackingandspalling,furtherdeterioration

Result Reductionsinstrengthandserviceability,

resultinginneedforrepairand/orreplacement



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time(e.g.heaviertrucks)

Consequences: Increaseddeteriorationduetooverloadsortostructuralinadequaciesresultingfromdesign

Result Structuresdeemedunsafeorunserviceable

andstrengtheningorreplacementisrequired



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Consequences: Variousdetrimentaleffectsonstructuralperformance,bothsafetyandserviceability

Result Needforrepair,rehabilitation,

strengtheningorreplacement



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INTRODUCTION Materials&Technologies

SHM FRP

Newandinnovativematerialsandmonitoringtoolsthatprolongtheservicelivesofstructureswhiledecreasingcosts



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WHATISSHM?

Assessingtheinserviceperformanceofstructuresusingavarietyofmeasurementtechniques

Leadingtosmartstructures

EXTERNALDISTURBANCES

STRUCTURE RESPONSE

SENSORSACTUATORS

CONTROLLER



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WHATISSHM?

Inspection Onsitenondestructiveexaminationtoestablishthe resentconditionofthestructure

Loadtesting Testofthestructureorpartthereofbyloadingtoeva ua e s e av ororproper es,or opre c sloadbearingcapacity

Monitoring Frequentorcontinuous,normallylongterm,observationormeasurementofstructuralconditionsoractions

Bjrn Tljsten


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WHATISSHM? Whymonitoring?

followupphysicalphenomenon

Bjrn Tljsten

assessmentofstructures

verificationofthestrengtheningeffects


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WHATISSHM? WhatisSHM becomingpopular?

EmerginguseofSHM isaresultof:

1.

The

increasing

need

forMonitoringofinnovativedesignsandmaterials

2.Theongoingdevelopmentof ewsensors e.g. er p c ensors , smar materialsetc.)Dataacquisitionsystems(DAS)

WirelessandinternettechnologiesDatatransmission,collection,archivingandretrievalsystems



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WHATISSHM? BodyAnalogy

MedicalDoctor SHM Engineer

Monitorpatientshealth

Monitorconditionofstructures

tocheckoverallhealth

Prescribescorrective

structuralhealth

Ifexcessivestressor

me c ne requ re e orma on,correc s u a o n



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WHATISSHM? SystemComponents

AcquisitionofData

CommunicationofData

http://www.smartstructuresinc.com

StorageofProcessedData RetrievalofData

DiagnosticsISIS Canada Educational Module 5


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WHATISSHM? SHM Categories

StaticFieldTesting:

DynamicFieldTesting:Stresshistor tests

DiagnostictestsProoftests

AmbientvibrationtestsDyn.LoadAllowance(DLA)tests

PeriodicMonitoring:Field testin

ContinuousMonitoring:Active monitorin

Teststodeterminechangesinstructure

Passivemonitoring



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WHATISSHM? ClassificationofSHM Systems

LevelIV , ,

L v l IIIDetectpresence,locationandseverityofdamage

Leve IIDetectpresenceandlocationofdamage

LevelI



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WHATISSHM? ClassificationofSHM Systems



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WHATISSHM? AdvantagesofSHM

AdvantagesofSHM

Increasedunderstandin ofinsitustructuralbehaviour

Earlydamagedetection

Decreaseddowntimeforinspectionandrepair

Developmentofrationalmaintenance/managementstrategies

Increasedeffectivenessinallocationofscarceresources

Enablesandencouragesuseofnewandinnovativematerials



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METHODOLOGY

IdealSHM system:

1.

Information

on

demand

about

a

structures

health2.Warningsregardinganydamagedetected

DevelopmentofaSHM systeminvolvesutilizing

Computers

Materials

ommun cat onStructuresSensors


IntelligentProcessing

DataCollection


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METHODOLOGY SystemComponents



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METHODOLOGY Monitoringprinciples

Competenceof theMonitoringobjectives

ri geengineer

What?Bridgemodel Constraints

When?Designmodelmonitoringsystem

How?Designofphysical

monitoringsystem

Installationofphysicalmonitoring

Competenceofthemonitoringengineer

Validationofmodeland physicalmonitoringsystem

After Glauco Feltrin, EMPA, 2007

Maintenanceofmodelandphysicalmonitoringsystem


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0

0.05

]

g

0 1 2 3 4 5 6-0.1

-0.05d[m

Displacement D1

0

0.05

m]

Interactionbridge

0 1 2 3 4 5 6-0.1

-0.05d[

Displacement D2

time [s]

DomodelresultsmatchImproved

model/monitoring withmonitoringresults?corre a on

Bjrn Tljsten

o ca ono mo e


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g

Verificationbymonitoring notnew

TestingofasteeltrussinEnglandforarailwaybridgeinIndiainthe19thcentury



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METHODOLOGY 1 AcquisitionofData

Thecollection

of

raw

data:strains,deformations,

accelerations,temperatures,moisture levels,acousticem ss onsan oa s

(a)SelectionofSensors

Appropriateandrobustsensors

Whataspectsofthestructurewillbemonitored?



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(b)SensorInstallationandPlacement

Mustbeabletoinstallsensorswithoutalterin thebehaviour of

thestructure

, ,

accessoriesmustbeaccountedforintheinitialstructuraldesign



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(c)TransfertoDataAcquisitionSystem(DAS)

Method1LeadwiredirectphysicallinkbetweensensorandDAS

notpracticalforsomelargestructures

long

lead

wires

increase

signal

noise

Method WirelesstransmissionMore ex ensive

SignalsaretransferredmoreslowlyandarelesssecureUseisexpectedtoincreaseinthefuture



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(d)DataSamplingandCollection

GeneralRule:

Theamountofdatashouldnotbesoscantyasto jeopardize

,overwhelminterpretation

Issues:NumberofsensorsanddatasamplingratesData sortin for onsite stora e

Insomecases,largevolumesofdata


esu :Efficient

strategies

needed

for

data

sampling

and

storing


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Whatismonitored,howandwhy?

oa

Magnitudeandconfigurationofforcesappliedtoa

Aretheyasexpected?

How

are

they

distributed?

Deformation

Excessiveorunexpecteddeformation,mayresultinaneedforrehabilitationorupgrade


Measuredusingvarioustransducers


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Strain

Intensityofdeformation

Magnitudeandvariationofstrainscanbeexaminedto

evaluatesafetyandintegrity Measuredusin strain au es

FOS,electrical,vibratingwire,etc.

empera ure Changesintemperature causedeformation

ThermalExpansion

Repeatedcyclescancausedamage Temperatureaffectsstrainreadings


MeasuredusingThermocouples(TC),Temperature

IndicatorControllers(TIC),thermistors


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Acceleration

Loadscauseaccelerationsofstructuralcomponentsand

viceversa

Howisthestructureresistingaccelerationsandtheresultin loads?

Widespreaduseinhighlyseismicregions Measuredusingaccelerometers

WindSpeedandPressure Windloadscangovernthedesignoflongspan bridgesand

tallbuildingsRecordspeedandpressureatvariouslocations


i i i f


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AcousticEmissions

Whencertainstructuralelementsbreak,theyemitnoise

AElistensforthenoises,andpinpointslocations

usingtriangulation Usedin osttensionedconcreteandcablesta edstructures

Measuredusingmicrophones

VideoMonitoring Timestampedvideosandpicturescanbeusedtowitness

extremeloadsoreventsDatacanbecorrelatedwithimages


Emerginginternetcameratechnologyisused

HO OLOGY 2 C i ti f D t


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METHODOLOGY 2 CommunicationofData

ReferstodatatransferfromtheDAStoanoffsitelocation

Allowsforremotemonitoring,eliminationofsitevisits

Telephone

lines

DAS Internet Offsite

Wireless


METHODOLOGY 3 I t lli t P i f D t


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METHODOLOGY 3 IntelligentProcessingofData

Requiredbeforedatacanbestoredforlaterinterpretationandanalysis

Thegoalistoremovemundanedata,noise,thermal,or

Easier

FasterMoreaccurate


METHODOLOGY 4 Storage of Processed Data


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METHODOLOGY 4 StorageofProcessedData

DatamaybestoredforverylongperiodsoftimeRetrieveddatamustbeunderstandableDatamustnotbecorruptedSufficientmemorymustbeavailable

Datafilesmustbewelldocumentedforfuture

inter retation

Itiscommontodisregardrawdataandstoreonly

processedoranalyzeddataThisdoesnotallowforreinterpretation


METHODOLOGY 5 Diagnostics


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METHODOLOGY 5 Diagnostics

ExtremelyimportantcomponentConvertsabstractdatasignalsintousefulinformationaboutstructuralresponseandcondition

Methodolo used de ends onTypeofstructureTypeandlocationofsensorsused

MotivationformonitoringStructuralresponsesunderconsideration


METHODOLOGY 6 Data Retrieval


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METHODOLOGY 6 DataRetrieval

Whenstoringdataforretrieval,consider1.Significanceofdata2.Confidenceinanalysis

Remember:

The oal o SHM is to rovide detailed h sical data whichcanbeusedtoenablerational,knowledgebasedengineeringdecisions.


SENSOR TECHNOLOGY


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SENSORTECHNOLOGY

ManysensortypesarecurrentlyavailableChoiceforSHM dependsonvariousfactors

Fibre opticsensors(FOSs)

Emergingforinfrastructureapplications


SENSOR TECHNOLOGY FOS


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SENSORTECHNOLOGY FOS

FOSAdvantages:

Stability Increasedlongtermstabilityanddecreased

noise

Nonconductive Immunetoelectromagneticandradio

fre uenc interference

Flexibility MultiplexingandDistributedsensing

Convenience Light,smalldiameters,noncorrosive,


em e a e,eas y on a e

SENSOR TECHNOLOGY How do FOSs work?


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SENSORTECHNOLOGY HowdoFOSs work?

Sensingusingopticalfibres andtechniques

Lightbeam laser issentdownanopticalfibre towardagauged

lengthLi htwavesmeasurechan esinstate i.e.elon ationorcontractionChangeinreflectedlightwavesiscorrelatedtostrainreadingDemodulationunitcalculatesstrainfromlightsignalsandgives

DASconvertsvoltagetostraindataforprocessing


SENSOR TECHNOLOGY Sensor Technology


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SENSORTECHNOLOGY SensorTechnology


SENSOR TECHNOLOGY Sensor Technology


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SENSORTECHNOLOGY SensorTechnology

Characteristics:

Useforstaticanddynamicmonitoring

Embeddable,bondableandweldableGau elen thcanvar fromcmtomorethan1kmThermalandmechanicalstrainscanbeseparated

WidthofcracksStraintransferinbondedjoints

tress

concentrat ons


SHM SYSTEM DESIGN


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SHM SYSTEMDESIGN

1.DesignIssues DefinitionofSHM objectives

Typesofmonitoring

Sensorplacement

DurabilityandlifespanofSHM


SHM SYSTEM DESIGN


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SHM SYSTEMDESIGN

2.InstallationIssues Contractoreducation

Sensoridentification

Sensordamageduring

construction

Structuralchangesinducedby

presence

o

SHM system


Protect onaga nstdeteriorationandvandalism

SHM SYSTEMDESIGN


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3.Use

Issues Disseminationof

performanceresults

Continuit ofknowled e

Datacollectionandmanagement

Publicawareness


SHM SYSTEMDESIGN Methodology


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1. Identifythedamageordeteriorationmechanisms

.

responseTheoreticalandnumericalmodelsofstructure

3.Establishcharacteristicresponseofkeyparameters sta s sens t v tyo eac toanappropr ate eve o deterioration

4.SelecttheparametersanddefineperformanceindexRelateschangesinresponsetolevelofdeterioration


SHM SYSTEMDESIGN Methodology


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5.DesignsystemSelectionofsensors,dataacquisitionandmanagementData inter retation

6.InstallandcalibrateSHM system(baselinereadings)

7.Assessfielddataandadaptsystemasnecessary


THEFUTUREOFSHM


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SHMisincreasinglyseenasanimportanttoolinthemaintenanceofsustainableinfrastructuresystems

Ongoingadvancementsareexpected,emergingtechnolo iesinclude:

Smart

CompositesLiveStructures


THEFUTUREOFSHM SmartComposites


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SmartComposites

. .

provideinformationabouttheconditionofthestructuralcom onent

Muscle/MemberAnalogy:

Muscleshavenervecellsembeddedinthemthatprovide

Smartcompositeshavesensorsinsidethatprovideinformation

theconditionsofthemuscles

condition


THEFUTUREOFSHM SmartComposites


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LiveStructures

analysis

Livestructuresarecapableof:

Sensingloads,

deformations,

and

damage

Correctingandcounteringtheloadeffects

Accom lishedusin emer in selfactuatin materials


SUMMARYANDCONCLUSION


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StructuralHealth

Monitoring

optionsfor

monitoring,analysingandunderstandingthe

healthofourinfrastructures stems

Provide

essential

tools

toengineers

who

must

take

steps

toimprovethesustainabilityofinfrastructuresystems




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Ste 1

Assessmentprocedureforthebridge

Initialassessment

Sitevisits several

LaboratoryinvestigationsInvestigationsofLoadModels

Step3

StudyofdocumentsStudyandcarriedout

simplecalculations

StrengtheningcalculationsMonitoringRefinedcalculations,FEmodels

Intermediateassessment

Furtherinspections

Destructivetesting

Step2

,

DetailedcalculationsInvestigationsofloadingetcPlanningfortestingetc

DesignModelsUltimateLimitStateVerification

Bjrn TljstenStep4

. Detai e ana ysisNonlinearFEModels



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CaseStud Thernskldsviksbrid e 2006

StructuralAssessment

S1:Survey S1:QuestionnaireBridgeowner/Consultant Bridgeowner/consultant

S2:Conditionassessment

Visual Ins ections

S2:SimpleFE

Consultant

S2:Nondestructivetests

Radar ultrasonic tests etc.

S2:Materialsamples

S3:Laboratorytesting

Bjrn Tljsten

Drillingofcores,pulloffetc. Concrete,Steeletc.



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CaseStud Thernskldsviks brid e 2006

StructuralAssessment

S3:Sensorinstallation

Specialistconsultant

120

130

Slab

26 Ftg A1 30 Ftg A5 V

120

130

Slab

26 Ftg A1 30 Ftg A5 V

S4:Loadtest1

Testinginstitutes 010

20

30

40

50

60

70

80

90

100

110

0 500 1000 1500 2000 2500 3000 3500 4000Timevik2(Platta1U1.bin)

0

10

20

30

40

50

60

70

80

90

100

110

0 500 1000 1500 2000 2500 3000 3500 4000Timevik2(Platta1U1.bin)

S4:Strengthening

Specialistcontractors

S4:Loadtest2Testinginstitutes

S4:Detailedevaluation

Bjrn Tljsten



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PredictedLoadCarryingCapacity

Bjrn Tljsten



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PredictedLoadCarryingCapacity

Eurocode 2,

=

30o

P=6,1MN = o =

MCFT,Response,30o P=8,7MN

o =, , ,

Test, 30o P=11,7MN

Bjrn Tljsten



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Periodiclongtimemonitoring

CaseStudy Kallkllan 1998

80.00

Strains

40.00

60.00

ra

in

[e-6]

20.00

St

0.00

Time

Before strengthening After strengthening "Long-term" behavior

Measurementofstrains

Bjrn Tljsten


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st

SHM details 2

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