supervision ian f. c. smith - documents.epfl.ch · supervision ian f. c. smith edce 2011 modelling...

ENAC /

How do structures really behave?Why does it matter?... to save money!Author James-A. Goulet

Supervision Ian F. C. Smith EDCE 2011/

Modelling uncertainties

p i

j

kLm

no x0

y0z0

PROBABILITY-BASEDOBJECTIVE FUNCTION

0

=

THE ‘’MOST-LIKELY‘’ MODELIS OFTEN NOT THE RIGHT MODEL

SEVERAL MODELS EXPLAINMEASUREMENTS

1STEP

Objectivefunction

Measuring and Modelling

2STEP Developping an objective function

3STEP

Interpreting measurements

Measurement uncertainties

+

MODEL FILTERINGMODEL FITTING

AccelerometersInclinometersTransducerStrain guagesetc...

(Model calibration does not work!)

0

Objectivefunction

Prediction-measure

(Sensor location #i)

Prediction-measure

(Sensor location #j)

Set of acceptablemodels

Single ‘’most-likely’’model

Used to compare measured values to the predictions ofseveral thousand models

Prediction-measure

(Sensor location #i)

Prediction-measure

(Sensor location #j)

(One per sensor location) 0

0

0Boundary conditions?

What is the prestress level?

What is theexpansion joint condition?

What is the saddle condition?

Sensors

ENAC /

How do structures really behave?Why does it matter?... to save money!Author James-A. Goulet

Supervision Ian F. C. Smith EDCE 2011/

Modelling uncertainties

p i

j

kLm

no x0

y0z0

PROBABILITY-BASEDOBJECTIVE FUNCTION

0

=

THE ‘’MOST-LIKELY‘’ MODELIS OFTEN NOT THE RIGHT MODEL

SEVERAL MODELS EXPLAINMEASUREMENTS

1STEP

Objectivefunction

Measuring and Modelling

2STEP Developping an objective function

3STEP

Interpreting measurements

Measurement uncertainties

+

MODEL FILTERINGMODEL FITTING

AccelerometersInclinometersTransducerStrain guagesetc...

(Model calibration does not work!)

0

Objectivefunction

Prediction-measure

(Sensor location #i)

Prediction-measure

(Sensor location #j)

Set of acceptablemodels

Single ‘’most-likely’’model

Used to compare measured values to the predictions ofseveral thousand models

Prediction-measure

(Sensor location #i)

Prediction-measure

(Sensor location #j)

(One per sensor location) 0

0

0Boundary conditions?

What is the prestress level?

What is theexpansion joint condition?

What is the saddle condition?

Sensors