performance‐based seismic assessment of skewed...
TRANSCRIPT
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Performance‐BasedSeismicAssessmentofSkewedBridges
PEER
byErtugrulTaciroglu,UCLA
FarzinZareian,UCI
PEER Transportation Systems Research Program
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Collaborators Majid Sarraf, PARSONS
Anoosh Shamsabadi, Caltrans
Students Peyman Khalili Tehrani, UCLA
Peyman Kaviani, UCI
Ali Nojoumi, UCLA
Pere Pla-Junca, UCI
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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