Interaction of MSE Abutments with Superstructures under Seismic Loading

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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

30

35

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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36

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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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40

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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41

Additional Schematics

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42

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Additional Schematics

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43

Construction

44

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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47

Instrumentation Plan

Longitudinal Section L1


Transverse Section T1

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48

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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52

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


4 2010 Maule 0.40 109 Displacement


6 1994 Northridge 0.58 88.7 Displacement


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


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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 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)


0

0.5

1.0

1.5

2.0

0 1 2 3 4 5

L1

L2

T1

Ele

vati

on (

m)


Test 4 - Imperial Valley Motion Test 4 - Northridge Motion

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58

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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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59

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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62

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Bridge Seat and Deck Accelerations

63

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

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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


-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.)


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


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


Longitudinal Section L2 Transverse Section T1

max strain

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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

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Interaction of MSE Abutments with Superstructures under Seismic Loading

Engineering

Transcript of Interaction of MSE Abutments with Superstructures under Seismic Loading