WUT - KULeuven

Research topics and perspectives at K.U.Leuven

Luc Schueremans

April 17 , Warszawa, Poland

http://www.kuleuven.be/bwk/materials

2

Research TopicsKVB LS

(historical)mortars + grout; (historical)

masonry; timber, steel

LVDW

JVD JM AB

Cement and concrete

chemistry & technology;

fiber reinfored concrete

(Historical) binders and lime based materials;

microscopic materialresearch

Polymer-gemodified concrete

soilGroundmechanics &

foundationtechniques [EC7],

Environment-geotechnics Road construction

Risc-analysis [EC0]

Probabilistic Design

Statistical data-processing

RLICC

Preventive Maintenance

Unesco-Chair

SPRECOMAH

monitoring -geometry

Concrete design [EC2]

Structural Design [EC0]:

Steel [EC3]; timber [EC5]; masonry [EC6]

Evaluation of existingmonumental structures

NDT - monitoring

Consolidation

strengthening

4/17/2009

Structural reliability for the built heritage

ShipsShips

Nuclear Nuclear InstallationsInstallations Structural Structural

analysis*analysis*

Power generation Power generation

and distributionand distribution PipelinesPipelines AerospaceAerospace

Road and rail vehiclesRoad and rail vehicles Onshore Onshore Buildings and Buildings and

StructuresStructures

Bridges and Bridges and TunnelsTunnels

Offshore Offshore structuresstructures

ReliabilityReliability

analysisanalysis

*[ASRANET:(http://www.intes.de/asra/asra.html) Advanced Structural Reliability Analysis Network) ]

4/17/2009

Structural reliability for the built heritage

Level 0 Rules of thumb and the so-called “elastic method”.

Level I These methods are based on the partial safety factor principle.

Level II Probabilistic techniques, that use First and Second Order Reliability Methods [EN 1990, 2002].

Level III Level III methods are most accurate. These compute the exact probability of failure of the whole structural system, or structural elements, using the exact probability density function of all random variables.

Tendency towards level III:Tendency towards level III:

Computational capacity and speedComputational capacity and speed

Continuous improvement of reliability methodsContinuous improvement of reliability methods

increasing accuracy of structural modelsincreasing accuracy of structural models

Availability of material models and dataAvailability of material models and data

UserUser--friendly software applicationsfriendly software applications

4/17/2009

Structural reliability for the built heritage

Structural Structural

analysisanalysis

ββ, p, pff

Random variablesRandom variables

R, SR, S, a, , a, θθ

FEM:FEM:

NascomNascom

PERMASPERMAS

DianaDiana

AnsysAnsys

PowerframePowerframe

Nastran,...Nastran,...

FORM/SORMFORM/SORM

Numerical Numerical IntegrationIntegration

Monte CarloMonte Carlo

&&

Directional Directional SamplingSampling

ReliabilityReliability

analysisanalysis

Analytical model: g=RAnalytical model: g=R--SS

Implicit model g=f(R,SImplicit model g=f(R,S,a,,a,θθ))

Tendency towards level III: 5. Target failure probabilitiesTendency towards level III: 5. Target failure probabilities

ββTT, p, pf,Tf,T

4/17/2009

How safe must it be ?Economical factor Cf Warning factor W

not seriousseriousvery serious

101 0.1

Fail-Safe conditionGradual failure with some warning likelyGradual failure hidden from viewSudden failure without previous warning

0.010.10.31.0

Activity factor Ac Social criterion factor – “Preservation value” Sc

- Post-disaster activity- Normal activities :

BuildingsBridges

- High exposure structures (offshore)

0.3

1.03.010.0

- Places of public assembly, dams (historical buildings of great importance for mankind, listed by UNESCO e.g.)- Domestic buildings, offices, trade buildings, industrial buildings (listed historical buildings)- Bridges- Towers, masts, off-shore structures

0.005

0.05

0.55

SScc

( )p f = −Φ βpf 10-1 10-2 10-3 10-4 10-5 10-6 10-7

β 1.3 2.3 3.1 3.7 4.2 4.7 5.2

Structural reliability for the built heritageββTT, , ppf,Tf,T

p Stn

AW

CfT cL

p

cf= −10 4

4/17/2009

How safe must it be ?Economical factor Cf Warning factor W

not seriousseriousvery serious

1010.1

Fail-Safe conditionGradual failure with some warning likelyGradual failure hidden from viewSudden failure without previous warning

0.010.10.31.0

Activity factor Ac Social criterion factor – “Preservation value” Sc

- Post-disaster activity- Normal activities :

BuildingsBridges

- High exposure structures (offshore)

0.3

1.03.010.0

- Places of public assembly, dams (historical buildings of great importance for mankind, listed by UNESCO e.g.)- Domestic buildings, offices, trade buildings, industrial buildings (listed historical buildings)- Bridges- Towers, masts, off-shore structures

0.005

0.05

0.55

SScc

( )p f = −Φ βpf 10-1 10-2 10-3 10-4 10-5 10-6 10-7

β 1.3 2.3 3.1 3.7 4.2 4.7 5.2

Structural reliability for the built heritagep S

tn

AW

CfT cL

p

cf= −10 4 54 107.11

3.0101100

005.010 −− =××

××=

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Structural reliability methodssystem failure probabilityefficiëncy: nLSFE

applicability large nsmall pf

implicit LSFrobuustness

Integration methods: - analytical/numerical integration- directional integration

Simulatiemethodes: (Importance Sampling) Monte Carlo/ Directional Sampling

FORM/SORM: 1st and 2nd order reliability methodsMethods with adaptable response surface (2de order polynomial):

- FORM/SORM with adaptable response surface (ARS)- Directional Sampling : DARS (III; D-ID)- Monte Carlo: MCARS (III:D-ID)

Structural analysis

β, pf

Random variablesR, E, a, θ

Reliabilityanalysis

βT, pfT

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Structural reliability methods

Methods with adaptable Meta-Model- response surface- Splines- Neurale Netwerken- Ordinary Kriging

- Directional Sampling- Monte Carlo

Structural analysis

β, pf

Random variablesR, E, a, θ

Reliabilityanalysis

βT, pfT

( ) ∑∑∑= ≥=

++=n

1i

n

ijjiij

n

1iii0MM xxaxaaxg

( ) ( )∑=

−ψ=N

1jjcjMM xxaxg

θ+ϕ= ∑

=

n

1ikii,kk xwy

Schueremans L., Van Gemert Dionys, “Kriging as an alternative for increased predictive power of meta-models in structural reliability”, International Journal of Materials and Structural Reliability, Vol. 4, No. 2 , 185-198, September 2006

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Applications in design and assessmentDesign of structures Evaluation of extisting structures

- Design of foundation strengthening

- Structural safety of Romanesque city wall of Leuven

Schueremans L., Van Gemert D., “Assessing the safety of existing structures: reliability based assessment framework, examples and application”, JCEM , Lithuania, Issue 2, Vol X, 2004, pp. 131-141.

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Applications in design and assessmentDesign of structures Evaluation of extisting structures

-Probabilistic design of portal steel frame

- Safety of arches

5 m

12.5 m

IPE 360

IPE

400

KA

KB KC

KD

pqqsn

Steelgrade: S235

[Post-doc research: (http://www.kuleuven.be/bwk/materials/Research) - IWT/OZM/030932 – example worked out in collaboration with Buildsoft NV]

Schueremans L., Van Gemert D. and Smars P., “Safety assessment of masonry arches using probabilistic methods”, International Journal for Restoration of Buildings and Monuments, Aedificatio Verlag - Fraunhofer IRB Verlag, Heft 5, pp. 517-538, 2001

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Applications in design and assessmentDesign of structures Evaluation of extisting structures

-flood risk analysis of the Scheldt basin

Blanckaert J., Bulckaen D. (IMDC NV), Schueremans L., “Average annual flood risk analysis of the Scheldt basin”, Australian Journal of Civil Engineering, Vol.4, No. 1, pp. 73-87, 2007.

: Flooded area (based on hydrodynamic model): Output node from hydrodynamic model: Flood cell around node for calculation of total damage function: River in hydrodynamic model0 €

100.000.000 €

200.000.000 €

300.000.000 €

400.000.000 €

500.000.000 €

600.000.000 €

700.000.000 €

800.000.000 €

4 5 6 7 8 9 10 11 12 13 14Water Height TAW [h]

Dam

age

[€]

1. Antwerp - city center2. Industrial area - harbour at Oosterweel3. Residential Area - Kieldrecht4. Rural area - Kalken (Laarne)

1

2

34

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Applications in design and assessmentDesign of structures Evaluation of extisting structures

-Chloride penetration in RC-structures in marine conditions: Long term evaluation of effectiveness of preventive hydrophobic treatment

Schueremans L., Van Gemert D., Giessler S. “Chloride penetration in RC-structures in marine environment – long term assessment of a preventive hydrophobic treatment”, Construction and Building Materials, Volume 21, Issue 6, June 2007, Pages 1238-1249. (SCI-IF: 0.343 (2005); 0.506 (2006))

δδ

δδ

=δδ

xC

Dxt

C0,00

0,50

1,00

1,50

2,00

2,50

3,00

3,50

0 20 40 60 80 100Depth [mm]

% C

l- /cem

1996199820051-2mm

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Possibilities of applications

Structural analysis

Random variablesR, E, a, θ

Reliabilityanalysis

IN:tL

Pfβ

/

OUT:Pfβ

tL

pf(t)β(t)

Long term behavior - durability:•Corrosion of steel bars•Alkali-Silica-Reaction

Material degradation:•Carbonation•Freeze-thaw cycles•Timber (wrot-fungi-insects)

Deterioration processes:•Chloride penetration

Time dependent material behavior:•Creep

⇒ Probabilistic design supports:

•Durable design (sustainability);

•Performance based design.