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NUMERICALMODELINGOF

FOUNDATIONDEFORMATION

DUETOFAULTRUPTURE

A. Giannakou, J. Chacko, O. Zarzouras, and W. Chen

NorthAnatolianFault

Istanbul

Izmir

South Approach Viaduct

Izmit Bay Bridge South Approach Viaduct

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IdentificationofActiveFaultsinInterpretedSiteinvestigationData

Active Faults near Bridge Alignment

Identified Secondary Faults Geophysical Data

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Identified Secondary Faults Geophysical Data

Beginning of South Approach ViaductAnchorage Location

Pier 1 Pier 2

Identified Secondary Faults Geotechnical Data

Beginning of South Approach ViaductPier 1 Pier 2

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South Approach Viaduct Pier Foundation Design

P01

P02

P03P04

InthenearshoreareawherefaultswereidentifiedingeophysicaldataPier

foundationswerelocatedinbetweenidentifiedfaults

Imagingoffaultfeatureswasnotpossibleintheonshoreareas,duetohigh

watertable

and

large

thicknesses

of

very

recent

sediments

Foundationdesignneedstoaccommodatethepotentialforfaultsbeingpresent

attheindividualfoundationlocations

2,475yearsurfacefaultrupturedisplacements:1mhorizontaland0.5mvertical

Failure of the Bolu Viaduct in the 1999 Duzce Eq due to Fault Rupture

Anastasopoulos et al (2008)

Case Histories of Bridge Failures due to Fault

Rupture

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Collapse of Two Bridges in the 1999 Chi Chi Eq due to Fault Rupture

Anastasopoulos et al (2008)

Case Histories of Bridge Failures due to Fault

Rupture

Foundation Systems Performance Against Fault

RupturePerformance of Pile Foundation

to Fault Rupture

Performance of Shallow

Foundation to Fault Rupture

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Step 1: Detailed

Soil-Foundation Model

Step 2: Detailed

Superstructure Model

Problem Definition and Design Approach

Idealized Soil Profile

Elevation(m)

StrengthParameters(kPa)

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Sands

Clays

Soil Constitutive Model

HorizontalDistanced(m)

y(m)

e_plastic

0.00E+00 4.00E-02

8.00E-02 1.20E-01

1.60E-01 2.00E-01

Contour interval= 2.00E-02Exaggerated Grid Distortion

Magnification = 1.000E+00Max Disp = 9.694E-01

Validation of Soil Model - Centrifuge Test of

Reverse Fault Rupture

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y(m)

HorizontalDistanced(m)

e_plastic 0.00E+00 4.00E-02

8.00E-02 1.20E-01

1.60E-01 2.00E-01

Contour interval= 2.00E-02Exaggerated Grid Distortion

Magnifica tion = 1.000E+00Max Disp = 9.847E-01

Validation of Soil Model - Centrifuge Test of

Normal Fault Rupture

Mesh Sensitivity

1mx1m elements 2mx2m elements

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Fault Offset

Foundation 26m x 36m

Numerical Model

Modeling of Strike Slip Fault Rupture

ShearStrainContours

FreeFieldFaultRupture

Propagation

Diversionof

Fault

Rupture

DuetoFootingPresence

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Sensitivity to Fault Offset Location with respect to

Footing Centerline

FaultOffsetat+10mFaultOffsetat+5mFaultOffsetat5m

FaultOffset

at

10

mFault

Offset

at

0mFree

Field

Ca s e1b

Ca s e1c

Ca s e1a

Ca s e1d

Ca s e1e

Sensitivity to Fault Offset Location with respect to

Footing CenterlineCa s e1b

Ca s e1c

Ca s e1a

Ca s e1d

Ca s e1e

1.2

1.0

0.8

0.6

0.4

0.2

0

0.2

1.2

1.0

0.80.6

0.4

0.2

0

VerticalDisplacement(m)

HorizontalDispla

cement(m)

30 20 10 0 10 20 30

DistancefromFoundationCenterline(m)

Fault offset -10 m

Fault offset -5 m

Fault offset 0 m

Fault offset 5 m

Fault offset 10 m

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Sensitivity to Fault Rupture Dip Angle

Dip

angle

65

o

Dipangle50o

Found Case 1a

Found Case 4a

Found Case 4b

FF Ca se1a

FF Ca se4a

FF Ca se4b

Sensitivity to Fault Rupture Dip Angle

Dip Angle 80o - Base Case

Dip Angle 65o

Dip Angle 50o

Free Field, Dip Angle 80o

Free Field, Dip Angle 65o

Free Field, Dip Angle 50o

FoundCa se1a

FoundCa se4a

FoundCa se4b

FF Case 1a

FF

Case

4a

FF Case 4b

1.2

1.0

0.8

0.6

0.4

0.2

0VerticalDisplacement(m)

HorizontalDisplacem

ent(m)

DistancefromFoundationCenterline(m)30 20 10 0 10 20 30

1.2

1.0

0.8

0.6

0.4

0.2

0

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Sensitivity to Fault Rupture Direction

45o

Angle

Strike

FoundationFoundation

Transverse

to

Bridge

Axis

F oundCase1a

F oundCase2

FF Case1a

FF Case2

Sensitivity to Fault Rupture Direction

F oundCase1a

F oundCase2

FF Case1a

FF Case2

1.2

1.0

0.8

0.6

0.4

0.2

0

0.2

0.4

1.2

1.0

0.8

0.6

0.4

0.2

0

0.2

VerticalDisplacement(m)

HorizontalDispla

cement(m)

DistancefromFoundationCenterline(m)40 30 20 10 0 10 20 30 40

Transverse to Bridge Axis - Base Case

45oAngle

Free Field, Base Case

Free Field, 45oAngle

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Thefoundation

system

has

been

found

to

play

akey

role

intheresponseofstructuressubjectedtofaultinducedgroundmovement

Structuresrestingonrigidandcontinuousfoundationsystems(suchasaraft,oraboxtypefoundation)havedemonstratedtobecapableofachievingaverysatisfactoryperformance,irrespectiveofthefaultingtype

ThetypeoffootingselectedfortheIzmitBridgeSouth

ApproachViaduct

diverts

fault

rupture

around

the

footing

compressessurfaceasperities,thusleadingtosmallerdifferentialdisplacements,andthefootingblockitselfremainsstructurallysound

Conclusions

Rotationsandtorsionsontheorderof0.5to1degreeareobservedasthefoundationelementspreadsouttheoverallgrounddisplacements

Greatertranslationisobservedforcaseswherethefaultruptureisclosertotheedgesofthefooting,whereasmorerotation/torsionisobservedfortherupturebeneaththefooting

Conclusions