Variability Characteristics of Structural Health Variability Characteristics of Structural Health Monitoring Data and Monitoring Data and Development of Engineering Report ToolDevelopment of Engineering Report Tool

Nicolás A. LondoñoNicolás A. Londoño

David T. LauDavid T. Lau

Department of Civil & Environmental EngineeringDepartment of Civil & Environmental Engineering

Carleton UniversityCarleton University

Ottawa, CanadaOttawa, Canada

SAMCO Summer AcademyZell am See, Austria

Sept 5-9, 2005

OverviewOverview

► IntroductionIntroduction► Computer ToolsComputer Tools► Research using Confederation Research using Confederation

Bridge field monitoring dataBridge field monitoring data1.1. Design properties verificationDesign properties verification

2.2. Variability of monitoring dataVariability of monitoring data

► Engineering Report ToolEngineering Report Tool► ConclusionsConclusions

Confederation BridgeConfederation Bridge

Monitoring SystemMonitoring System

Sensors

Data logger

On Site Computers

Carleton University

Processing

Internet

Analysis (System Identification)• Frequency

• Mode-shape

• Damping ratios

Condition Assessment

Engineering Reporting and Interpretation

LAN

Wind scenario Traffic scenario

40

seconds

600

seconds

Data characteristicsData characteristics

Wind scenarios

Traffic scenarios

Stochastic Subspace IdentificationStochastic Subspace Identification

Data cross-correlations

TN

k

refkik

refi N

1

1ˆ yyR

Output-only monitoring data Nkk ,...,1, y

Block Toeplitz Matrix

refi

refi

refi

refrefi

refi

refrefi

refi

refi

RRR

RRR

RRR

T

ˆ...ˆˆ............

ˆ...ˆˆ

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ˆ

2212

21

11

|1

refii

refrefrefi

i

refi ΓOGAGGA

CA

CA

C

T

......

1

1

|1

GCAR 1 ii

Singular Value Decomposition T

T

TTref

i 111

2

1121|1 VSU

V

V

00

0SUUUSVT

21

11SUO iTref

i 121

1 VSΓ

Stochastic State-Space Model Matrices

:),:1(:)),1(:1( lilil ii OOA

:,:1 liOC

FrequenciesMode Shapes

Damping Ratios

1ΨΛΨACΨV

kkk

kkk

vCxy

wAxx

1State Space

model

SPPLASH – Signal Processing PLatform for Analysis of Structural Health

Identified 2.76 HzIdentified 2.76 Hz

Theoretical 2.59 HzTheoretical 2.59 Hz

MAC 0.89MAC 0.89

Verification StudyVerification Study – Modal Frequencies –– Modal Frequencies –

Mod

e N

um

ber

Mod

e N

um

ber

Typ

eTyp

e

EXPERIMENTAL FREQUENCYEXPERIMENTAL FREQUENCY Experimental – Theoretical Experimental – Theoretical Frequency DifferenceFrequency Difference

MeanMean(Hz)(Hz)

MinMin (Hz)(Hz)

MaxMax (Hz)(Hz)

Range ofRange ofVariability Variability

(%)(%)

StdStd (% of (% of mean)mean)

Beam Beam E35E35 (%)(%)

Beam Beam E43E43 (%)(%)

Shell Shell E35E35 (%)(%)

Shell E43Shell E43 (%)(%)

11 T T 0.340.34 0.320.32 0.370.37 1616 5.85.8 2222 1010 66 -4-422 TT 0.470.47 0.460.46 0.480.48 55 1.41.4 22 -8-8 -3-3 -12-1233 VV 0.570.57 0.520.52 0.630.63 1919 6.86.8 2121 99 1515 4444 VV 0.650.65 0.640.64 0.660.66 33 11 1212 11 33 -7-755 VV 0.680.68 0.650.65 0.710.71 99 2.12.1 1010 -1-1 -- --77 VV 0.920.92 0.890.89 0.950.95 77 22 1616 55 77 -4-488 VV 0.970.97 0.950.95 0.990.99 44 1.51.5 1818 77 -- --

1010 VV 1.621.62 1.61.6 1.661.66 44 1.31.3 -- -- -- --1111 VV 1.811.81 1.781.78 1.861.86 55 1.21.2 1313 22 1010 -1-11212 VV 2.732.73 2.702.70 2.792.79 33 0.90.9 1717 55 -- --1313 VV 2.832.83 2.762.76 2.912.91 55 2.02.0 1515 44 77 -3-31414 VV 2.882.88 2.832.83 2.942.94 44 1.71.7 -- -- -- --1616 TP31-ToTP31-To 3.303.30 3.263.26 3.343.34 33 1.01.0 -- -- 44 -6-61818 VV 3.43.4 3.293.29 3.473.47 55 1.51.5 -- -- -- --1919 V-LV-L 3.793.79 3.713.71 3.923.92 55 1.81.8 2323 1111 1010 552323 4.714.71 4.664.66 4.744.74 22 0.60.6 -- -- -- --2525 VV 5.135.13 5.035.03 5.205.20 33 1.31.3 1616 55 -- --AveragesAverages -- -- -- 4.84.8 1.81.8 1515 44 77 -3-3

Verification StudyVerification Study – Modal Damping and MAC – Modal Damping and MAC ––

Mod

e N

um

ber

Mod

e N

um

ber

Fre

qu

en

cy

Fre

qu

en

cy

MODAL DAMPING MODAL DAMPING RATIOS (RATIOS ())

MODAL ASSURANCE MODAL ASSURANCE CRITERIONCRITERION (MAC)(MAC)

Mean Mean (%)(%)

Standard Standard Deviation Deviation

(% of mean)(% of mean)

ExperimentExperimentalal

ExperimentaExperimental vs.l vs.

FE (shell)FE (shell)

11 0.340.34 1.91.9 6666 0.940.94 0.890.8922 0.470.47 1.71.7 3939 0.900.90 0.850.8533 0.570.57 3.83.8 3737 0.820.82 0.870.8744 0.650.65 1.41.4 7373 0.890.89 0.970.9755 0.680.68 2.12.1 3737 0.850.85 --77 0.920.92 1.51.5 4242 0.910.91 0.980.9888 0.970.97 1.61.6 4242 0.920.92 --

1010 1.621.62 1.61.6 7070 0.930.93 --1111 1.811.81 1.51.5 5353 0.940.94 0.960.961212 2.732.73 0.80.8 5252 0.910.91 --1313 2.832.83 1.31.3 5757 0.920.92 0.890.891414 2.882.88 1.01.0 5959 0.890.89 --1616 3.303.30 0.60.6 4848 0.560.56 0.730.731818 3.43.4 0.80.8 5050 0.900.90 --1919 3.793.79 0.90.9 5757 0.910.91 0.580.582323 4.714.71 0.80.8 4242 0.850.85 --2525 5.135.13 0.80.8 4848 0.860.86 --

AverageAveragess

-- 1.31.3 5454 0.880.88 0.790.79

VariabilityVariability-Sources--Sources-

►Numerical uncertaintiesNumerical uncertainties Deviation from model assumptionsDeviation from model assumptions

►Data non-stationarityData non-stationarity►Non-whiteness of the inputsNon-whiteness of the inputs

Measurement noiseMeasurement noise Computational uncertaintiesComputational uncertainties

►Use of finite datasetsUse of finite datasets►Analyst inputAnalyst input

► Physical UncertaintiesPhysical Uncertainties Environmental and loading fluctuationsEnvironmental and loading fluctuations

►Temperature effectsTemperature effects►Bridge-vehicle coupling, etc.Bridge-vehicle coupling, etc.

Baseline VariabilityBaseline Variability

Mode Mode shape shape

variabilitvariabilityy

Baseline variabilityBaseline variability

General variabilityGeneral variability

Temperature EffectTemperature Effect

Temperature (Hz)Temperature (Hz)

Mod

al Fre

qu

en

cy (

Hz)

Mod

al Fre

qu

en

cy (

Hz)

Variability vs. sensitivityVariability vs. sensitivity

Engineering Report ToolEngineering Report Tool

►MotivationMotivation Enhance feedback given to bridge owners Enhance feedback given to bridge owners

and operators and operators Provide timely systematic information of Provide timely systematic information of

engineering relevance for decision engineering relevance for decision supportsupport

►RequirementsRequirements Automated file sorting and processingAutomated file sorting and processing Easy to search database Easy to search database

ENDEND

Confederation Bridge Monitoring Confederation Bridge Monitoring DataData

► Truck Traffic induced vibrationTruck Traffic induced vibration

► Wind storm Wind storm (Nov. 7 2001)(Nov. 7 2001)

► Typical ambient vibrationTypical ambient vibration