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Performance‐BasedSeismicAssessmentofSkewedBridges

PEER

byErtugrulTaciroglu,UCLA

FarzinZareian,UCI

PEER Transportation Systems Research Program

2

Collaborators Majid Sarraf, PARSONS

Anoosh Shamsabadi, Caltrans

Students Peyman Khalili Tehrani, UCLA

Peyman Kaviani, UCI

Ali Nojoumi, UCLA

Pere Pla-Junca, UCI

3

Outline

1. Skew bridges & project goals

2. Modeling skew abutment response

3. Developing NLTH simulation models for skew bridges

4. Exploring and quantifying skew-bridge response

5. Discussion

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GeneralProblemPerformance assessment of skewed abutment bridges

•  Appropriate modeling of bridge superstructure.

•  Appropriate modeling of bridge abutment.

•  Selection of appropriate input ground motions.

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PreviousStudiesStraight Abutment:

Aviram, Mackie, and Stojadinovic 2008

Johnson et al. (2009), Kotsoglou and Pantazopoulou (2010), Mackie

and Stojadinovic (2007), Paraskeva et al. (2006)

Skewed Abutment:

Abdel-Mohti and Pekcan (2008) Meng and Lui (2000), Maragakis (1984), Wakefield et al. (1991),

Ghobarah and Tso (1974)

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GroundMoFons

Pulse-Like

Faul

t-Nor

mal

Fa

ult-P

aral

lel

0 0.5 1 1.5 2 2.5 3 3.5 40

0.5

1

1.5

2

2.5

3

Period [sec]

Sa[g

]

0 0.5 1 1.5 2 2.5 3 3.5 40

0.5

1

1.5

2

2.5

3

Period [sec]

Sa[g

]

0 0.5 1 1.5 2 2.5 3 3.5 40

0.5

1

1.5

2

2.5

3

Period [sec]

Sa[g

]

0 0.5 1 1.5 2 2.5 3 3.5 40

0.5

1

1.5

2

2.5

3

Period [sec]

Sa[g

]

0 0.5 1 1.5 2 2.5 3 3.5 40

0.5

1

1.5

2

2.5

3

Period [sec]

Sa[g

]

0 0.5 1 1.5 2 2.5 3 3.5 40

0.5

1

1.5

2

2.5

3

Period [sec]

Sa[g

]

Soil-Site Rock-Site

 Three sets of GMs were selected by the PEER Transportation Research Program  40 GMs per set  Three types of GMs: Pulse-like, soil-site, and rock-site  Fault Normal: longitudinal direction; Fault parallel: transverse direction  The GMs are from mid- to large-magnitude  Near-source GMs  Selected GMs have a variety of spectral shapes, durations, and directivity periods

4.0 2.0 0.0

1.0

2.0

3.0

4.0 2.0 0.0

1.0

2.0

3.0

4.0 2.0 0.0

1.0

2.0

3.0

4.0 2.0 0.0

1.0

2.0

3.0

4.0 2.0 0.0

1.0

2.0

3.0

4.0 2.0 0.0

1.0

2.0

3.0

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AnatomyofanAbutment

Seat-type

There are also “monolithic abutments”

plan view

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SkewBridgeChallenges

  Deck rotation (esp. for single span bridges)

  Backfill response (near field)

  Shear key failure

  Unseating

  High seismic demands on columns

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SkewBridgeChallenges

  Deck rotation (esp. for single span bridges)

  Backfill response (near field)

  Shear key failure

  Unseating

  High seismic demands on columns

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SkewBridgeChallenges

  Deck rotation (esp. for single span bridges)

  Backfill response (near field)

  Shear key failure

  Unseating

  High seismic demands on columns

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SkewBridgeChallenges

  Deck rotation (esp. for single span bridges)

  Backfill response (near field)

  Shear key failure

  Unseating

  High seismic demands on columns

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SkewBridgeChallenges

  Deck rotation (esp. for single span bridges)

  Backfill response (near field)

  Shear key failure

  Unseating

  High seismic demands on columns

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SkewBridgeChallenges

  Deck rotation (esp. for single span bridges)

  Backfill response (near field)

  Shear key failure

  Unseating

  High seismic demands on columns

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Skew‐angledAbutmentsSkew happens

? ?

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Input parameters for “Hardening Soil” PLAXIS model

Lnom

AbutmentModeling

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AbutmentModeling

Lskew ≠ Lnom

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straight abutment with wall-width wr

skew abutment with wall-width wr

skew abutment with deck-width wr

AbutmentModeling

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BridgeModelingThe Jack Tone Road On-Ramp Overcrossing

The La Veta Avenue Overcrossing

The Jack Tone Road Overhead

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BridgeMatrixBridges Col.

Elev. Symmetry Asymmetry

00° 15° 30° 45° 60° 00° 15° 30° 45° 60° 2 Span-Single Col. (A)

Higher AUS0 AUS1 AUS2 AUS3 AUS4 AUA0 AUA1 AUA2 AUA3 AUA4 Lower ALS0 ALS1 ALS2 ALS3 ALS4 ALA0 ALA1 ALA2 ALA3 ALA4

2 span-Multi Col. (B)

Higher BUS0 BUS1 BUS2 BUS3 BUS4 BUA0 BUA1 BUA2 BUA3 BUA4 Lower BLS0 BLS1 BLS2 BLS3 BLS4 BLA0 BLA1 BLA2 BLA3 BLA4

3 Span-Multi Col. (C)

Higher CUS0 CUS1 CUS2 CUS3 CUS4 CUA0 CUA1 CUA2 CUA3 CUA4 Lower CLS0 CLS1 CLS2 CLS3 CLS4 CLA0 CLA1 CLA2 CLA3 CLA4

Developed after: Mackie & Stojadinovich

Abutment Spring

Elastic Deck Abutment Spring

Plastic Hinge

Simple Support for Multi-Column

Fixed Support for single column

Plastic Hinge

ddeck = 0.04L

Dcol = 0.8 ddeck

ρ = ρoriginal

Hmax = 8Dcol

Horiginal

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AbutmentModeling

a a a a

Simplified Model

Dual-Rigid Model

Friction Model

Skewed Model

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0

50

100

150

200

0 2 4 6 8 10

Forc

e (k

ips)

Displ. (in)

ZL-1 ZL-2 ZL-3 ZL-4 ZL-5

!"

ACU

OBT

Dec

k!

Bac

kfill

so

il!

! =tan"

tan60o# 30%

AbutmentModeling

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-2800

-2400

-2000

-1600

-1200

-800

-400

0-10 -8 -6 -4 -2 0

Forc

e (k

ips)

Displ. (in)

Bridge-A Bridge-B Bridge-C

VN,C= 2360 kips VN,B= 1810 kips VN,A= 755 kips

Brid

ge “

C”

Brid

ge “

B”

Brid

ge “

A”

ShearKeyModeling

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DeckRotaFon–BridgeA

0 15 30 45 60

0.002

0.004

0.006

0.008

0.01

0.012

Skew Angle

Dec

k R

otat

ion

(rad)

PULSESOILROCK

Bridge “A”, Lower, Symt.:

Old Models

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0 15 30 45 60

2

4

6

8

Skew Angle

Col

umn

Drif

t Rat

io (%

)

PULSESOILROCK

ColumnDriNRaFo–BridgeA

Bridge “A”, Lower, Sym.

Old Models

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0 15 30 45 60

2

4

6

8

Skew Angle

Col

umn-

1 D

rift R

atio

(%)

PULSESOILROCK

ColumnDriNRaFo–BridgeB

Bridge “B”, Lower, Sym.

Old Models

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0 15 30 45 600

0.25

0.5

0.75

Skew Angle

Dec

k R

otat

ion

(radx

10e-

3)

0306090120150

DeckRotaFon–BridgeA

Median Response, Bridge “A”, Lower, Symt.

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0 15 30 45 600

2

4

6

8

10

12

14

16

Skew Angle

Dec

k R

otat

ion

(radx

10e-

3)

0306090120150

DeckRotaFon–BridgeA

Median Response, Bridge “A”, Lower, Symt. NO SHEAR KEY MODELED

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0 15 30 45 600

1

2

3

4

Skew Angle

Col

umn

Drif

t Rat

io (%

)

0306090120150

ColumnDriNRaFo–BridgeA

Median Response, Bridge “A”, Lower, Symt.

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0 15 30 45 600

2

4

6

8

Skew Angle

Col

umn

Drif

t Rat

io (%

)

0306090120150

ColumnDriNRaFo–BridgeA

Median Response, Bridge “A”, Lower, Symt. NO SHEAR KEY MODELED

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DeckRotaFon–BridgeA

0 15 30 45 600

0.25

0.5

0.75

Skew Angle

Dec

k R

otat

ion

(radx

10e-

3)

0306090120150

Pulse 1, Bridge “A”, Lower, Symt.

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0 15 30 45 600

1

2

3

4

Skew Angle

Col

umn

Drif

t Rat

io (%

)

0306090120150

ColumnDriNRaFo–BridgeA

Pulse 1, Bridge “A”, Lower, Symt.

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ProbabilityofCollapse–BridgeA

Skew Angle = 0o Skew Angle = 30o Skew Angle = 60o

2

4

6

30

210

60

240

90

270

120

300

150

330

180 0

Number of GMs Caused CollapseBridge "A"Abut. skew= 015%

10%

2

4

6

30

210

60

240

90

270

120

300

150

330

180 0

Number of GMs Caused CollapseBridge "A"Abut. skew= 6015%

10%

2

4

6

30

210

60

240

90

270

120

300

150

330

180 0

Number of GMs Caused CollapseBridge "A"Abut. skew= 3015%

10%

Bridge “A”, Lower, Symt.

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0 15 30 45 600

0.25

0.5

0.75

Skew Angle

Dec

k R

otat

ion

(radx

10e-

3)

0306090120150

DeckRotaFon–BridgeB

Median Response, Bridge “B”, Lower, Symt.

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0 15 30 45 600

1

2

3

4

Skew Angle

Col

umn

Drif

t Rat

io (%

)

0306090120150

ColumnDriNRaFo–BridgeB

0 15 30 45 600

1

2

3

4

Skew Angle

Col

umn

Drif

t Rat

io (%

)

0306090120150

Median Response, Bridge “B”, Lower, Symt.

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5

10

15

30

210

60

240

90

270

120

300

150

330

180 0

Number of GMs Caused CollapseBridge "B"Abut. skew= 60

5

10

15

30

210

60

240

90

270

120

300

150

330

180 0

Number of GMs Caused CollapseBridge "B"Abut. skew= 30

5

10

15

30

210

60

240

90

270

120

300

150

330

180 0

Number of GMs Caused CollapseBridge "B"Abut. skew= 0

Bridge “B”, Lower, Symt.,

ProbabilityofCollapse–BridgeB

Skew Angle = 0o Skew Angle = 30o Skew Angle = 60o

38% 25%

38% 25%

38% 25%

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ShearKeyPerformance–BridgeA

0

15

30

45

60

0

5

10

15

20

1

2

3

4

5

6

Num

ber

of F

aile

d S

hear

K

eys

out o

f 40

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ShearKeyPerformance–BridgeB

0

15

30

45

60

0

5

10

15

20

1

2

3

4

5

6

Num

ber

of F

aile

d S

hear

K

eys

out o

f 40

1. Develop a three-DOF macro-element through numerical simulations with 3D continuum FE models and analytical considerations for torsionally flexible bridges.

2.  Finalize the bridge models including the new abutment model.

3.  Rotate Ground motions?

4.  Quantify the Sensitivity of Skew Bridge Response and Damage Metrics to Key Input Parameters

5.  Update Caltrans Seismic Design Criteria for Skew-Angled Bridges

NextSteps–AugustMeeFng

NextSteps–ThisMeeFng1. Develop a three-DOF macro-element through

numerical simulations with 3D continuum FE models and analytical considerations for torsionally flexible bridges.

2.  Finalize the bridge models including the new abutment model.

3.  Rotate Ground motions?

4.  Quantify the Sensitivity of Skew Bridge Response and Damage Metrics to Key Input Parameters

5.  Update Caltrans Seismic Design Criteria for Skew-Angled Bridges