interaction of mse abutments with superstructures under seismic loading
TRANSCRIPT
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Interaction of MSE Abutments with Superstructures under
Seismic Loading
Prof. John S. McCartney and Yewei Zheng
University of California San Diego
Department of Structural Engineering
Presentation to: GI of ASCE Orange County Section
November 3, 2016
Presentation Overview
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• Personal Research Introduction• Geotechnical Engineering at UCSD
– Faculty – Facilities – New MS in Geotechnical Engineering
• Technical Presentation: MSE Bridge Abutments– Motivation– Numerical Simulations with FLAC– Experimental Shaking Table Testing Program– Unsaturated Soil Aspect: Apparent Cohesion Estimates – Preliminary Results
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Personal Research Introduction
University of Colorado Boulder BS/MS 2002Faculty 2008-2014
University of Arkansas Faculty 2007-2008
University of California San DiegoFaculty 2014-present University of Texas at Austin
PhD 2007
Personal Research Focus
Material Characterization1. Unsaturated soil mechanics
• Effective stress evaluation• Yielding mechanisms under changes in temperature and suction• Compression behavior of soils to high stresses • Thermal volume change mechanisms• Measurement of hydro/thermal properties (SWRC, HCF, TCF, VHCF)
2. Geosynthetics engineering 3. Shear strength of tire-derived aggregatesFoundation Engineering1. Centrifuge and full-scale modeling2. Thermally active geotechnical systems (energy piles, geothermal heat
storage systems, thermal soil improvement)3. Offshore foundationsEarthquake Engineering and Soil-Structure Interaction1. Seismic response of unsaturated soils2. Seismic response of MSE bridge abutments
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Personal Research Introduction
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Geotechnical Faculty at UCSD
Ahmed Elgamal, Professor
Enrique Luco, Professor
John McCartney, Associate Professor
Ingrid Tomac, Asst. Research Scientist
Tara Hutchinson, Professor
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http://nees.ucsd.edu/facilities/shake-table.shtml
Large-scale experiments (UC San Diego outdoor shake table)
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Length of 6.7 m (22 ft), width of 3 m (9.6 ft) and height of 4.7 m (15.2 ft)
Facilities: Large Laminar Container
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Facilities: Container for Retaining Wall Testing on the Large Shaking Table
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Facilities: Powell Laboratory Shake Table
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UCSD South Powell Structural Lab Shake Table:
• Dimension: 10 ft. x 16 ft.
• Shaking DOF: 1D in N‐S direction
• Maximum gravity load: 80 kips
• Dynamic stroke: ± 6 in.
• Dynamic capacity: 90 kips
• Large laminar container
Facilities: Large Soil Pit for Foundation Testing
9m-deep soil pit and reaction wall for
foundation testing
Earth moving equipment:Bobcat, compactor, backhoe, crane
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Facilities: Full-Scale Soil-Borehole Thermal Energy Storage System
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0
5
10
15
20
25
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Thermal energy (GJ)
SolarBorehole Array
Actidyn Model C61-3
Capacity: 50 g-ton Nominal radius: 1.70m Max. acc.: 130g
UCSD Facilties: Geotechnical Centrifuge
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Facilities: Update of the Geotechnical Centrifuge
New features:• Data acquisition system and actuators• Containers (laminar, 3 clay tanks)• Shaking table• Control room
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UCSD Element‐Scale Geotechnical Laboratory
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Stress path triaxial testing setup
Standard soil characterization
equipment
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UCSD Element‐Scale Geotechnical Laboratory
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Geosynthetic pullout box
Large-scale direct shear/simple shear device for shear strength of
large particle materials (tire derived aggregates)
MS in Geotechnical Engineering at UCSDGoals:• Provide advanced degree option for students seeking to specialize in geotechnical
engineering• Meet demand of local employers and interest of current undergraduate students
• Build links to practice for students only interested in MS• Provide a recruiting tool for top MS students to continue for a PhD in
geotechnical engineering• Facilitate completion of MS coursework in 4 quarters plus a summer• Leverage and build upon existing courses in the department • Build upon existing strengths: earthquake engineering, soil-structure interaction,
computational geotechnics, and large-scale evaluation of geotechnical systemsProgram:• The M.S. degree program includes required core courses and technical electives• M.S. students must complete 48 units of graduate credits for graduation (12 courses)• Suggested focus sequences:
• Geotechnical engineering and geomechanics• Geotechnical earthquake engineering• Soil-structure interaction
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MS in Geotechnical Engineering at UCSDCore Courses (Students must take all four):• SE 271 Solid Mechanics for Structural & Aerospace Engineering• SE 241 Advanced Soil Mechanics• SE 242 Advanced Foundation Engineering• SE 250 Stability of Earth Slopes & Retaining WallsGeotechnical electives (students must select at least four):• SE 222 Geotechnical Earthquake Engineering• SE 226 Groundwater Engineering• SE 243 Soil-Structure Interaction• SE 244 Numerical Methods in Geomechanics• SE 247 Ground Improvement• SE 248 Engineering Properties of Soils• SE 207 Rock Mechanics • SE 207 Soil Dynamics • SE 207 Unsaturated Soil MechanicsOther technical electives (choose up to 4):• Students may select from a list of structural, computational mechanics, or geology
courses for the remaining 4 technical electives
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Geotechnical Engineering Graduate Student Organizations
CalGeo Student Chapter (Initiated 2015)• Brings in local geotechnical engineers for seminars
GeoInstitute Graduate Student Organization (Initiated 2016)• Facilitates engagement of graduate students in international geotechnical conferences
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Technical Presentation: Seismic Response of MSE Bridge Abutments
Roadways
Slopes
Embankments
Retaining walls
Bridge abutments• General trend is toward the use of GRS‐IBS abutments (close spacing, variable
lengths, specific design details from FHWA), but current study is on MSE bridge abutments (length = 0.7H, load applied to bridge seat on reinforced soil mass)
• GRS and MSE have many advantages over pile‐supported bridge abutments, including cost savings, easier and faster construction, and smoother transition
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Geosynthetics in transportation applications:
Acknowledgements
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• Project sponsors: – Caltrans
– Pooled fund members (WashDOT, UDOT, MDOT)
• Collaborators– Yewei Zheng, Ph.D. Candidate
– Prof. Benson Shing, Chair of SE at UCSD
– Prof. Patrick Fox, Head of CEE at Penn State University
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Research MotivationGRS bridge abutments have been widely used in US, but has not been adopted in California due to uncertainty about seismic performance:• Geotechnical: backfill settlement and facing displacement• Structural: bridge deck and seat movements, impact force between bridge deck and seat, and interaction between bridge superstructure and GRS abutment, overall philosophy of GRS vs. MSE (concerns with bridge deck being placed directly onto the reinforced soil mass)
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MSE wall performance
in Maule Earthquake,
Chile
Research MotivationGRS bridge abutments have been widely used in US, but has not been adopted in California due to uncertainty about seismic performance:• Geotechnical: backfill settlement and facing displacement• Structural: bridge deck and seat movements, impact force between bridge deck and seat, and interaction between bridge superstructure and GRS abutment, overall philosophy of GRS vs. MSE (concerns with bridge deck being placed directly onto the reinforced soil mass)
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MSE bridge abutment
performance in Maule
Earthquake, Chile
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Literature Review – Static Performance
• Lee and Wu (2004) reviewed several case studies of in‐service GRS abutments and reported satisfactory performance under service load conditions
• Adams et al. (2011) reported excellent performance for five in‐service GRS‐IBS abutments
• Field and laboratory static loading tests indicate that the GRS piers and abutments had satisfactory performance under design loads and relatively high load‐bearing capacity (Adams 1997; Gotteland et al. 1997; Ketchart and Wu 1997; Wu et al. 2001, 2006; Adams et al. 2011; Nicks et al. 2013)
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Literature Review – Seismic Performance
• El‐Emam and Bathurst (2004, 2005, 2007) performed a series of shake table tests on reduced‐scale GRS walls with a full‐height rigid facing panel
• Ling et al. (2005, 2012) conducted full‐scale shake table tests on GRS walls with modular block facing using fine sand and silty sand as backfill soils
• Yen et al. (2011) found that GRS abutments performed well from post‐earthquake reconnaissance for 2010 Maule Earthquake
• Helwany et al. (2012) conducted large‐scale shake table tests on a GRS abutment and found that it can sustain sin motion up to 1g without significant distresses
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Literature Review – Seismic Performance
ReferencesHeight
(m)Facing Backfill Reinforcement
Input
motionFindings
El‐Emam and
Bathurst
(2004, 2005,
2007)
1.0rigid
panelsand
polyester
geogridsinusoidal
facing lateral displacement could be
reduced by using smaller facing
panel mass, inclined facing panels,
longer reinforcement, stiffer
reinforcement, and smaller vertical
reinforcement spacing
Ling et al.
(2005, 2012)2.8
modular
block
sand/silty
sand
polyester
geogridearthquake
longer reinforcement at top layer
and smaller reinforcement vertical
spacing improved seismic
performance; vertical acceleration
has little influence; apparent
cohesion improved seismic
performance
Helwany et al.
(2012)3.6
modular
blocksand
woven
geotextilesinusoidal
GRS abutment remained functional
under sinusoidal motions up to 1.0 g
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Project Objectives
• Investigate performance of MSE abutments for service limit state, strength limit state, and extreme event limit state (seismic loading)
• Approaches:
• Numerical simulations using FLAC2D and FLAC3D
• ½ scale experimental physical modeling
• Improve design guidelines for external and internal stability of MSE bridge abutments for static and seismic loading
0 ~ 200 kPa 200 ~ > 1000 kPa extreme loadings
service limit strength limit extreme event limit
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Validation of FLAC 2D Model for Static Loading
Founders/Meadows Parkway Bridge, CO (Abu-Hejleh et al. 2002)
Extensive instrumentation
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Instrumented section 800 (after Abu-Hejleh et al. 2002)
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Validation of FLAC 2D Model for Static Loading
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Backfill Soil for Founders‐MeadowsBackfill treated as an elastic‐plastic material with Mohr‐Coulomb failure criterion, and Duncan‐Chang hyperbolic relationship
Comparison of measured and simulated triaxial test results
0
200
400
600
800
1000
1200
0 2 4 6 8 10
SimulatedMeasured (69 kPa)Measured (138 kPa)Measured (207 kPa)
Dev
iato
ric
Stre
ss (
kPa)
Axial Strain (%)
3' = 207 kPa
3' = 138 kPa
3' = 69 kPa
-1.0
-0.5
0
0.5
1.0
1.5
2.0
0 2 4 6 8 10
SimulatedMeasured (69 kPa)Measured (138 kPa)Measured (207 kPa)
Vol
um
etri
c St
rain
(%
) 3' = 69 kPa
3' = 138 kPa
Axial Strain (%)
3' = 207 kPa
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Reinforcement and Interfaces
linearly elastic‐plastic cable elements
Axial strain Relative displacement
Tensile force Shear force Shear strength
Normal force
interface elements with Coulomb sliding
Reinforcement: Interfaces:
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Initial Numerical Model Validation
In general, simulated results are in good agreement with field measurements, including displacements, lateral and vertical earth pressures, and tensile strains and forces in reinforcement
Lower Wall Construction
(Stage 1)
Bridge/Approach Construction
(Stages 2-6)
TrafficLoading
(Stage 7)
Incremental Maximum Lateral Facing Displacement (mm)
Measured 12 10 5
Simulated HR n/a 9 3
Simulated NHR 11 14 4
Incremental Bridge Footing Settlement (mm)
Measured n/a 12 10
Simulated HR n/a 13 5
Simulated NHR n/a 14 7
Incremental displacements for Founders/Meadows GRS bridge abutment (Zheng and Fox 2016 in JGGE)
0
1
2
3
4
5
6
0 2 4 6 8 10 12 14 16
MeasuredSimulated HRSimulated NHR
Ele
vati
on (
m)
Lateral Facing Displacement (mm)
Horizontal restraint (HR) from the bridge structure has important effect on abutment deflections
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Shake Table Testing Program
UCSD South Powell Structural Lab Shake Table:
• Dimension: 10 ft. x 16 ft.
• Shaking DOF: 1D in N‐S direction
• Maximum gravity load: 80 kips
• Dynamic stroke: ± 6 in.
• Dynamic capacity: 90 kips
Shake table testing has been successfully used to investigate seismic performance of GRS structures (El‐Emam and Bathurst 2004, 2005, 2007; Ling et al. 2005, 2012; Tatsuoka et al. 2009, 2012; Helwany et al. 2012)
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Longitudinal Testing
Powell lab shake table
Supportwall
Steel beams
Bridge deck
Bridge seat
GRS abutment
Upper wall
Sliding platform
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Transverse Testing
Bridge deck
Powell lab shake table
GRS abutment
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1g Shake Table Similitude Relationships
Scaling Factor λ=2
Length λ 2
Density 1 1
Strain 1 1
Mass λ3 8
Acceleration 1 1
Velocity λ1/2 1.414
Stress λ 2
Stiffness λ2 4
Force λ3 8
Time λ1/2 1.414
Frequency λ‐1/2 0.707
Similitude relationships for 1 g shake table test (Iai 1989)
Stress-strain relationships for model and prototype (Rocha 1957; Roscoe 1968)
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Goal: same strains in model and prototype
UCSD Sand Backfill
0
20
40
60
80
100
0.01 0.1 1 10
Per
cent
Fin
er (
%)
Particle Size (mm)
SW SandCu = 6.1, Cz = 0
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UCSD Sand Backfill
-2
0
2
4
6
8
0 2 4 6 8 10
Vol
um
etri
c St
rain
(%
)
3' = 7 kPa
3' = 138 kPa
Axial Strain (%)
3' = 207 kPa
3' = 69 kPa
3' = 34 kPa
0
200
400
600
800
1000
1200
0 2 4 6 8 10
Dev
iato
r S
tres
s (k
Pa)
Axial Strain (%)
3' = 69 kPa
3' = 34 kPa
3' = 7 kPa
3' = 138 kPa
3' = 207 kPa
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UCSD Sand Backfill
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Properties Value Specific gravity, Gs 2.61
Coefficient of uniformity, Cu 6.1Coefficient of curvature, Cz 1.0Maximum void ratio, emax 0.853Minimum void ratio, emin 0.371Recompression index, Cr 0.001Compression index, Cc 0.006Friction angle, ′ (°) 49.3
van Genuchten (1980) SWRC model parameter, vG (kPa‐1) 0.5
van Genuchten (1980) SWRC model parameter, NvG 2.1Drying curve volumetric water content at zero suction, d 0.319Wetting curve volumetric water content at zero suction, w 0.204
Residual volumetric water content, r 0
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0
250
500
750
1000
1 10 100
Ten
sile
Sti
ffn
ess
(kN
/m)
Strain Rate (%/min)
Geogrid Reinforcement
0
200
400
600
800
1000
1200
1400
0 5 10 15 20
Ten
sile
Loa
d (N
)
Strain (%)
10%/min - 1
10%/min - 2
10%/min - 3
0
200
400
600
800
1000
1200
1400
0 5 10 15 20
Ten
sile
Loa
d (N
)
Strain (%)
1%/min
5%/min
10%/min50%/min
100%/min
J = 580 kN/m
2%
Typical range
J = 378 kN/m
<1%
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Prototype (target) Model (used in tests)
Manufacturer Model ‐ Tensar LH800
Materials HDPE HDPE
Aperture Size (MD x TD) 9 in x 2.4 in 4.5 in x 1.2 in
Stiffness (kip/ft) 104 kip/ft 26 kip/ft
Length – 0.7H (ft) 9.8 4.9
Shaking Table Testing Plan
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Focus of this presentation
Test 1 2 3 4 5 6 7
Purpose
Reduced
Bridge
Load
Reinf.
spacing
Reinf.
stiffnessBaseline Baseline
Steel
mesh
Reduced
Bridge
Load
(repeat)
Shaking
DirectionLong. Long. Long. Long. Transverse Long. Long.
Reinf. spacing
(in)6 12 6 6 6 6 6
Reinf. stiffness
(kip/ft)25.9 25.9 12.9 25.9 25.9 327.6 25.9
Average bridge
surcharge (psf)940 1340 1340 1340 1340 1340 940
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Experimental/Numerical Design
• Bridge deck: 6.4 m long, 0.9 m wide, and 0.45 m deep, 2.3 m clearance
• Bridge load: 7 kN + 65 kN + 33 kN (vertical stress = 63 kPa)
• MSE abutment: 2.15 m high lower wall and 0.6 m high upper wall
• Reinforcement: 0.15 m spacing and 1.5 m (0.7H) long
GRS abutment
Bridge seat
Bridge deck
Support wall
Sliding platform
Upper wall
Shake table
Steel beam
Reaction wall
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Additional Schematics
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42
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Additional Schematics
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Construction
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44
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Test Setup
GRS abutment Support wall
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45
Test Setup
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46
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Instrumentation
Strain gages
String potentiometers
Linear potentiometers
Pressure cells
Load cells
Accelerometers
Dielectric sensors
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Instrumentation Plan
Longitudinal Section L1
Longitudinal Section L2
Transverse Section T1
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L1T1
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Estimates of Apparent Cohesion in Backfill
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49
0
0.5
1.0
1.5
2.0
2.5
0 2 4 6 8 10
Ele
vati
on, z
(m
)
Gravimetric Water Content (%)
S = wGs/e
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0.1 1.0 10.0 100.0 1000.0Degree of saturation, S
Suction, ψ (kPa)
DryingWetting
e = 0.50n = 0.33p = 0relative density = 60%
α = 0.85N = 1.80
α = 0.65N = 1.80
res
rese S
SSS
1
vGvG NN
vGeS1
11
Apparent Cohesion
50
50
0
0.5
1.0
1.5
2.0
2.5
0 2 4 6 8 10 12 14
DryingWetting
Ele
vati
on, z
(m
)
Apparent Cohesion (kPa)
f = ’tan’ = (Se)tan’
’ = (-ua)+s
’ = (-ua)+’ = (-ua)+Se
’ = (Se)
SWRC is needed for to estimate the apparent cohesion, but
otherwise the material properties for saturated/dry soil can be used
Apparent cohesion changes with wetting/drying:
Effective stress:
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Concept of Applied Shaking Motions
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51
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0 5 10 15 20 25 30 35 40
OriginalScaled
Acc
eler
atio
n (
g)
Time (s)
-150
-100
-50
0
50
100
150
0 5 10 15 20 25 30 35 40
OriginalScaled
Dis
pla
cem
ent
(mm
)
Time (s)
• Frequency of motion is reduced by √2, which shortens the duration
• Acceleration amplitude stays the same
• Displacement amplitude is scaled by half
Typical Response Spectrum of Applied Motion
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0
0.2
0.4
0.6
0.8
1.0
1.2
0.1 1 10
Target input
Shaking table
Psu
edo
Sp
ectr
al A
ccel
erat
ion
(g)
Frequency (Hz)
1940 Imperial Valley Motion (El Centro Station): 5% damping
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Applied Shaking Motions
Shaking
NumberMotion
Maximum
Acceleration (g)
Maximum
Displacement
(mm)
Control Mode
1 White Noise 0.1 26.1 Acceleration
2 1940 Imperial Valley 0.31 66 Displacement
3 White Noise 0.1 26.1 Acceleration
4 2010 Maule 0.40 109 Displacement
5 White Noise 0.1 26.1 Acceleration
6 1994 Northridge 0.58 88.7 Displacement
7 White Noise 0.1 26.1 Acceleration
8 Sin @ 0.5 Hz 0.05 50 Displacement
9 Sin @ 1 Hz 0.1 25 Displacement
10 Sin @ 2 Hz 0.2 12.5 Displacement
11 Sin @ 5 Hz 0.25 2.5 Displacement
12 White Noise 0.1 26.1 Acceleration
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Applied Shaking Motions
• White noise – characterize frequencies
• Earthquake motions (frequencies scaled)
1. 1940 Imperial Valley (El Centro) – PGA = 0.31 g/ PGD = 66 mm
2. 2010 Maule (Concepcion) – PGA = 0.40 g/ PGD = 109 mm
3. 1994 Northridge (Newhall) – PGA = 0.58 g/ PGD = 89 mm
• Sinusoidal motions (0.5, 1, 2, and 5 Hz)
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0 4 8 12 16 20 24 28
Acc
eler
atio
n (g
)
Time (s)
-100
-50
0
50
100
0 4 8 12 16 20 24 28
Dis
plac
emen
t (m
m)
Time (s)
-60
-40
-20
0
20
40
60
0 5 10 15 20 25 30 35 40
Dis
pla
cem
ent
(mm
)
Time (s)
-3
-2
-1
0
1
2
3
0 5 10 15 20 25 30 35 40
Dis
pla
cem
ent
(mm
)
Time (s)
0.5 Hz 5 Hz
Imperial Valley ‐ AccelerationImperial Valley ‐ Displacement
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Bridge Seat Settlements
Test 4, Maule Earthquake
SE SW
NENW
Bridge Seat Instrumentation
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55
Confinement of the soil at the back of the wall (south)
leads to less variable strains during shaking
-2
0
2
4
6
8
10
0 20 40 60 80 100
NWNE
SWSE
Set
tlem
ent
(mm
)
Time (s)
-2
0
2
4
6
8
10
0 20 40 60 80 100
Set
tlem
ent (
mm
)
Time (s)
Bridge Seat Settlements
TestVerticalStress (kPa)
Residual Bridge Seat Settlements (mm)
Bridge Deck Placement
Imperial Valley Motion
Maule Motion
Northridge Motion
Test 1 (reducedload)
44 1.4 2.7 2.5 ‐
Test 4 (baseline)
63 2.1 1.5 1.5 2.1
Note: Values are incremental for each testing stage, and are the average of the settlements of the four corners
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Lateral Facing Displacements
• Lateral face displacements generally increase with elevation• Residual displacements are incremental for each shaking event• Maximum dynamic lateral facing displacements are greater than residual values
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0
0.5
1.0
1.5
2.0
0 1 2 3 4 5 6
EOC - AbutmentImperial Valley - ResidualImperial Valley - Max
Maule - ResidualMaule - Max
Ele
vati
on, z
(m
)
Lateral Facing Displacement (mm)
Lateral Facing Displacements
• Displacements for L1 are larger than L2 despite greater confinement in L1 • Displacements are larger for the Northridge Earthquake, which has larger PGA• Displacements for T1 are larger than L1 and L2
0
0.5
1.0
1.5
2.0
0 0.5 1.0 1.5 2.0
L1
L2
T1
Ele
vati
on (
m)
Lateral Facing Displacement (mm)
0
0.5
1.0
1.5
2.0
0 1 2 3 4 5
L1
L2
T1
Ele
vati
on (
m)
Lateral Facing Displacement (mm)
Test 4 - Imperial Valley Motion Test 4 - Northridge Motion
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Relative Movements of Bridge Seat and Top of the Wall
Test
Vertical
Stress
(kPa)
Relative Bridge Seat Lateral Movements (mm)
Imperial
Valley
Motion
Maule
Motion
Northridge
Motion
Test 1 44 2.4 6.4 ‐
Test 4 63 ‐0.2 0.4 0
Note: Incremental average values, (‐) is toward the back of the wall
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Fundamental Frequency from White Noise Motions
60
60
0
5
10
15
20
25
0 5 10 15 20 25
Shaking event 1Shaking event 3Shaking event 5
Fou
rier
Am
plit
ud
e
Frequency (Hz)
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Acceleration Amplification
• Acceleration amplification increases with elevation
• Amplification ratios increase from retained soil zone to reinforced soil zone to wall facing
• Amplification ratios are larger for L1 than L2
Imperial Valley Earthquake
0
0.5
1.0
1.5
2.0
0.8 1.0 1.2 1.4 1.6 1.8
L1 - Wall FacingL1 - Reinforced Soil ZoneL1 - Retained Soil Zone
L2 - Reinforced Soil ZoneL2 - Retained Soil Zone
Ele
vati
on (
m)
Acceleration Amplification Ratio
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61
Bridge Seat and Deck Accelerations
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
0 4 8 12 16 20 24 28
Bridge SeatBridge Deck
Acc
eler
atio
n (
g)
Time (s)
Imperial Valley Earthquake
Bridge deck: Max acceleration = 0.53 g Amplification ratio = 1.29
Bridge seat:Max acceleration = 0.64 g Amplification ratio = 1.56
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Bridge Seat and Deck Accelerations
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63
0
5
10
15
20
25
0 5 10 15 20 25
Bridge deck/shaking table
Bridge seat/shaking table
Fou
rier
Am
plit
ud
e
Frequency (Hz)
Bridge Seat and Deck Movements
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64
-16
-12
-8
-4
0
4
8
12
16
0 20 40 60 80 100
EastWest
Hor
izon
tal D
isp
lace
men
t (m
m)
Time (s)
-16
-12
-8
-4
0
4
8
12
16
0 20 40 60 80 100
Hor
izon
tal D
isp
lace
men
t (m
m)
Time (s)
Test 4 – Maule Motion
2/16/2017
33
Bridge Seat and Deck Movements
65
65
-16
-12
-8
-4
0
4
8
12
16
0 20 40 60 80 100
Rel
ativ
e H
oriz
onta
l Dis
pla
cem
ent
(mm
)
Time (s)
Test 4 – Maule Motion
Bridge Seat and Deck Movements
-30
-20
-10
0
10
20
30
0 4 8 12 16 20 24 28
Rel
ativ
e D
isp
lace
men
t (m
m)
Time (s)
Relative Displacement
(mm)1940 Imperial Valley 2010 Maule 1994 Northridge
Residual 2.1 1.4 ‐4.3
Maximum ‐ 6.8/8.3 ‐9.7/9.8 ‐30/20.6
Test 4 Bridge deck sliding relative to bridge seat (relative displacement)
Northridge Earthquake
seismic joint closed
moving away from bridge seat
moving towards bridge seat
seismic joint remained open
66
66
2/16/2017
34
Seismic Joint Closure
0
10
20
30
40
50
60
0 4 8 12 16 20 24 28
Sei
smic
Joi
nt
Size
(m
m)
Time (s)
Northridge Earthquake
closed
remained open
67
67
Horizontal Contact Forces: Earthquake
-100
-50
0
50
100
0 4 8 12 16 20 24 28
Load Cell - EastLoad Cell - West
Hor
izon
tal C
onta
ct F
orce
(k
N)
Time (s)
Horizontal contact forces for the Northridge Earthquake, Test 4
68
68
2/16/2017
35
Reinforcement Strains
69
69
0
0.05
0.10
0.15
0.20
TopBottom
x = 0.46 m, z = 1.875 m
0
0.05
0.10
0.15
0.20
TopBottom
Rei
nfor
cem
ent
Stra
in (
%)
x = 0.46 m, z = 0.975 m
0
0.05
0.10
0.15
0.20
0 4 8 12 16 20 24 28
TopBottom
Time (s)
x = 0.46 m, z = 0.075 m
Test 4 1940 Imperial Valley Motion
Reinforcement Strains
70
70
Test 4 1940 Imperial Valley Motion
bridge load
0
0.1
0.2
0.3
InitialMaximumMinimumResidual
z = 1.95 mlayer 13
0
0.1
0.2
0.3
z = 1.50 mlayer 10
0
0.1
0.2
0.3
Rei
nfor
cem
ent
Stra
in (
%)
z = 1.05 mlayer 7
0
0.1
0.2
0.3
z = 0.60 mlayer 4
0
0.1
0.2
0.3
0 0.5 1.0 1.5 2.0
z = 0.15 mlayer 1
Distance from Facing, x (m)
2/16/2017
36
Reinforcement Strains (Max.)
Longitudinal Section L1
bridge load
Rei
nfor
cem
ent
Stra
in (
%)
00.10.20.30.40.5
EOCImperial ValleyMauleNorthridge
z = 1.95 mlayer 13
00.10.20.30.40.5
z = 1.05 mlayer 7
00.10.20.30.40.5
0 0.5 1.0 1.5 2.0
z = 0.15 mlayer 1
Distance from Facing (m)
bridge load
-0.10
0.10.20.30.4
EOCImperial ValleyMauleNorthridge
z = 1.95 mlayer 13
-0.10
0.10.20.30.4
z = 1.5 mlayer 10
-0.10
0.10.20.30.4
Rei
nfor
cem
ent
Stra
in (
%)
z = 1.05 mlayer 7
-0.10
0.10.20.30.4
z = 0.6 mlayer 4
-0.10
0.10.20.30.4
0 0.5 1.0 1.5 2.0
z = 0.15 mlayer 1
Distance from Facing (m)
bridge load
Rei
nfor
cem
ent
Stra
in (
%)
00.10.20.30.40.5
z = 1.95 mlayer 13
00.10.20.30.40.5
z = 1.05 mlayer 7
00.10.20.30.40.5
0 0.2 0.4 0.6 0.8 1.0
z = 0.15 mlayer 1
Distance from Facing (m)
Longitudinal Section L2 Transverse Section T1
max strain
71
71
Preliminary Findings• The bridge deck load was observed to lead to more static deformations (lateral and
vertical), but less dynamic deformations due to the greater geosynthetic confinement
• Lateral displacements are greater near the top of the wall but are not large enough to cause geotechnical concerns
• Lateral displacements and acceleration responses for section L1 are larger than L2
• Acceleration amplifies with elevation, and amplification ratios increase from retained soil zone to reinforced soil zone to wall facing
• Seismic‐induced reinforcement strains are largest near the wall face due to the inertia of the facing blocks
• Seismic joint might close during shaking and result in impact force on the bridge seat, but only during high frequency sinusoidal movements or Northridge EQ
• Overall, MSE abutments show good seismic performance in terms of lateral facing displacements and bridge seat movements
72
72