performance-based seismic assessment of skewed bridges
DESCRIPTION
Performance-Based Seismic Assessment of Skewed Bridges. PEER. by Ertugrul Taciroglu , UCLA Farzin Zareian , UCI. PEER Transportation Systems Research Program. Collaborators. Students. Peyman Khalili Tehrani , UCLA. Peyman Kaviani , UCI. Ali Nojoumi , UCLA. Pere Pla-Junca , UCI. - PowerPoint PPT PresentationTRANSCRIPT
1
Performance-Based Seismic Assessment of Skewed Bridges
PEER
byErtugrul Taciroglu, UCLA
Farzin Zareian, UCI
PEER Transportation Systems Research Program
2
CollaboratorsMajid Sarraf, PARSONSAnoosh Shamsabadi, Caltrans
StudentsPeyman Khalili Tehrani, UCLAPeyman Kaviani, UCIAli Nojoumi, UCLAPere Pla-Junca, UCI
3
Outline1. 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
4
General ProblemPerformance assessment of skewed abutment
bridges
• Appropriate modeling of bridge superstructure.• Appropriate modeling of bridge abutment.• Selection of appropriate input ground motions.
5
Previous Studies
Straight 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)
6
Ground Motions
Pulse-Like
Faul
t-Nor
mal
Faul
t-Par
alle
l
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 4
0
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 setThree types of GMs: Pulse-like, soil-site, and rock-siteFault Normal: longitudinal direction; Fault parallel: transverse directionThe GMs are from mid- to large-magnitude Near-source GMsSelected GMs have a variety of spectral shapes, durations, and
directivity periods
4.02.00.0
1.0
2.0
3.0
4.02.00.0
1.0
2.0
3.0
4.02.00.0
1.0
2.0
3.0
4.02.00.0
1.0
2.0
3.0
4.02.00.0
1.0
2.0
3.0
4.02.00.0
1.0
2.0
3.0
7
Anatomy of an Abutment
Seat-type
There are also “monolithic abutments”
plan view
8
Skew Bridge Challenges
Deck rotation (esp. for single span bridges)
Backfill response (near field)Shear key failure
Unseating
High seismic demands on columns
9
Skew Bridge Challenges
Deck rotation (esp. for single span bridges)
Backfill response (near field)Shear key failure
Unseating
High seismic demands on columns
10
Skew Bridge Challenges
Deck rotation (esp. for single span bridges)
Backfill response (near field)Shear key failure
Unseating
High seismic demands on columns
11
Skew Bridge Challenges
Deck rotation (esp. for single span bridges)
Backfill response (near field)Shear key failure
Unseating
High seismic demands on columns
12
Skew Bridge Challenges
Deck rotation (esp. for single span bridges)
Backfill response (near field)Shear key failure
Unseating
High seismic demands on columns
13
Skew Bridge Challenges
Deck rotation (esp. for single span bridges)
Backfill response (near field)Shear key failure
Unseating
High seismic demands on columns
14
Skew-angled AbutmentsSkew happens
??
15
Input parameters for “Hardening Soil” PLAXIS model
Lnom
Abutment Modeling
16
Abutment Modeling
Lskew ≠ Lnom
17
straight abutment with wall-width wr
skew abutment with wall-width wr
skew abutment with deck-width wr
Abutment Modeling
18
Bridge ModelingThe Jack Tone Road On-Ramp Overcrossing
The La Veta Avenue Overcrossing
The Jack Tone Road Overhead
19
Bridge MatrixBridges 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
r = roriginal
Hmax = 8Dcol
Horiginal
20
Abutment Modeling
aa aa
Simplified Model
Dual-Rigid Model
Friction Model
Skewed Model
21
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
€
β =tanα
tan60o × 30%
Abutment Modeling
22
-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
”
Shear Key Modeling
23
Deck Rotation – Bridge A
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
24
0 15 30 45 60
2
4
6
8
Skew Angle
Col
umn
Drif
t Rat
io (
%)
PULSESOILROCK
Column Drift Ratio – Bridge A
Bridge “A”, Lower, Sym.
Old Models
25
0 15 30 45 60
2
4
6
8
Skew Angle
Col
umn-
1 D
rift R
atio
(%
)
PULSESOILROCK
Column Drift Ratio – Bridge B
Bridge “B”, Lower, Sym.
Old Models
26
0 15 30 45 600
0.25
0.5
0.75
Skew Angle
Dec
k R
otat
ion
(rad
x10e
-3)
0306090120150
Deck Rotation – Bridge A
Median Response, Bridge “A”, Lower, Symt.
27
0 15 30 45 600
2
4
6
8
10
12
14
16
Skew Angle
Dec
k R
otat
ion
(rad
x10e
-3)
0306090120150
Deck Rotation – Bridge A
Median Response, Bridge “A”, Lower, Symt.NO SHEAR KEY MODELED
28
0 15 30 45 600
1
2
3
4
Skew Angle
Col
umn
Drif
t Rat
io (%
)
0306090120150
Column Drift Ratio – Bridge A
Median Response, Bridge “A”, Lower, Symt.
29
0 15 30 45 600
2
4
6
8
Skew Angle
Col
umn
Drif
t Rat
io (%
)
0306090120150
Column Drift Ratio – Bridge A
Median Response, Bridge “A”, Lower, Symt.NO SHEAR KEY MODELED
30
Deck Rotation – Bridge A
0 15 30 45 600
0.25
0.5
0.75
Skew Angle
Dec
k R
otat
ion
(rad
x10e
-3)
0306090120150
Pulse 1, Bridge “A”, Lower, Symt.
31
0 15 30 45 600
1
2
3
4
Skew Angle
Col
umn
Drif
t Rat
io (%
)
0306090120150
Column Drift Ratio – Bridge A
Pulse 1, Bridge “A”, Lower, Symt.
32
Probability of Collapse – Bridge A
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.
33
0 15 30 45 600
0.25
0.5
0.75
Skew Angle
Dec
k R
otat
ion
(rad
x10e
-3)
0306090120150
Deck Rotation – Bridge B
Median Response, Bridge “B”, Lower, Symt.
34
0 15 30 45 600
1
2
3
4
Skew Angle
Col
umn
Drif
t Rat
io (%
)
0306090120150
Column Drift Ratio – Bridge B
0 15 30 45 600
1
2
3
4
Skew Angle
Col
umn
Drif
t Rat
io (%
)
0306090120150
Median Response, Bridge “B”, Lower, Symt.
35
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.,
Probability of Collapse – Bridge B
Skew Angle = 0o Skew Angle = 30o Skew Angle = 60o
38%25%
38%25%
38%25%
36
Shear Key Performance – Bridge A
1
2
3
4
5
6
0
10
20
0
15
30
45
60
Abutment S
kew
Angle
150
12090
6030
0
Intercept Angle
Num
ber
of F
aile
d Sh
ear
Keys
out
of
40
37
Shear Key Performance – Bridge B
150
12090
6030
0
Intercept Angle Abutment S
kew
Angle
1
2
3
4
5
6
0
10
20
0
15
30
45
60
Num
ber
of F
aile
d Sh
ear
Keys
out
of
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
Next Steps – August Meeting
Next Steps – This Meeting1. 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