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Earthquake Engineering and theEarthquake Engineering and theAlaskan Way ViaductAlaskan Way Viaduct
Steve Kramer
University of Washington
Seattle, Washington
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
Caused by excessive ground shakingStrongly influenced by local soil conditions
StructuralStructural
GeotechnicalGeotechnical
Caused by ground failureStrongly influenced by local soil conditions
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
StructuralStructural
Mexico City, 1985Low bedrock accelerationsStrong amplificationStrong ground surface motions
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
StructuralStructural
Loma Prieta, 1989
Modest rock accelerationsStrong amplificationStrong ground surface motions
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
StructuralStructural
San Fernando, 1971
Strong motionLack of transverse reinforcement
Engineering for Earthquakes
Structures
Engineering for Earthquakes
Structural Engineering Considerations
• Design of new structures
• Retrofitting of existing structures
Engineering for Earthquakes
Design Considerations
Performance objectives
Immediate Occupancy Life Safety Collapse Prevention
Immediate OccupancyImmediate Occupancy Life SafetyLife Safety
Collapse PreventionCollapse Prevention Seismic Loading on Structures
Earthquake motion
Gravity load (vertical)
Weight of structure
Weight of contents
Vertical
seismic
loads
Horizontal
seismic
loads
Seismic Loading on Structures
Earthquake motion
Seismic Loading on Structures
LengtheningShortening
Rotation
To prevent excessive movement, must restrain
rotation and/or lengthening/shortening
Types of structures
Moment frame
Strong
beam/column
connections
resist
rotation
Types of structures
Braced frameDiagonal bracing
resists lengthening
and shortening
Concrete Shear Wall
Shear wall
resists
rotation and
lenthening/
shortening
Structural Materials
MasonryVery brittle if unreinforcedCommon in older structuresCommon facing for newer structures
Structural Materials
Timber
Structural Materials
ConcreteHeavy, brittle by itselfDuctile with reinforcement
Rebar
Structural Materials
SteelLight, ductileEasy connections
Structural Damage
Masonry
IranSan Francisco
Watsonville
Structural Damage
Timber
Structural Damage
Timber
Soft first floor
Reinforced Concrete Column
Structural Damage
Reinforced Concrete
Axial
Lateral
Overturning
Rebar
Structural Damage
Reinforced Concrete
Insufficient
confinement
Insufficient
confinement
Structural Damage
Reinforced Concrete
Increased
confinement
Structural Damage
SteelFractured weld
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
Occurs in loose, saturated sands
Grain structure collapses
Pore pressure increases
Effective stress decreases
Strength and stiffness decrease
LiquefactionLiquefaction
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LiquefactionLiquefaction
Niigata, 1964
LiquefactionBearing failure
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LiquefactionLiquefaction
Kobe, 1995
LiquefactionLateral spreading
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LiquefactionLiquefaction
Niigata, 1964
LiquefactionLateral spreadingPile foundation failure
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LiquefactionLiquefaction
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
Can occur due to liquefaction
Can occur in non-liquefiable soil
LandslidesLandslides
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LandslidesLandslides
Peruvian Andes, 1970
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LandslidesLandslides
Yungay, Peru
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LandslidesLandslides
Yungay, Peru
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LandslidesLandslides
Peruvian Andes, 1970
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LandslidesLandslides
Peruvian Andes, 1970
Source
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LandslidesLandslides
Peruvian Andes, 1970
Source
Yungay
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LandslidesLandslides
Yungay, Peru
Before After
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
Retaining Structure FailuresRetaining Structure Failures
Active pressure on back of wall increases
Passive pressure on front of wall decreases
Wall translates and/or rotates
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
Retaining Structure FailuresRetaining Structure Failures
Port of Seattle, 1965
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
Retaining Structure FailuresRetaining Structure Failures
Port of Kobe, 1995
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
Retaining Structure FailuresRetaining Structure Failures
Port of Kobe, 1995
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LifelinesLifelines
GasElectrical powerWaterSewerStorm drainData
HighwaysBridgesPorts
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LifelinesLifelines
GasElectrical powerWaterSewerStorm drainData
HighwaysBridgesPorts
Required forphysical health
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LifelinesLifelines
GasElectrical powerWaterSewerStorm drainData
HighwaysBridgesPorts
Required forphysical health
Required foreconomic health
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LifelinesLifelines
Natural Gas
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LifelinesLifelines Water
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LifelinesLifelines
Ports
Principal Types of Earthquake DamagePrincipal Types of Earthquake Damage
LifelinesLifelines
Transportation
Alaskan Way ViaductAlaskan Way Viaduct
• 2.2 miles long
• 86,000 vehicles per day
• North of Yesler
Designed by City of Seattle
Constructed in 1950
• South of Yesler
Designed by Washington State DOH
Constructed in 1956
Alaskan Way ViaductAlaskan Way Viaduct
© 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping
SeattleSeattleSeattleSeattleSeattleSeattleSeattleSeattleSeattle
Yesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler Terrace
Elliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott Bay
999999999999999999
Harborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview Hospital
U S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina Hospital
Mason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason Hospital
Union DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street Station
Seattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle University
1ST
4TH
BO
RE
N
E MADISON
RAIN
IER
AVE S
S 1
ST
STE
WART
YESLER WAY
I-5
RAMP
I-90
© 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping
AWV
© 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping
SeattleSeattleSeattleSeattleSeattleSeattleSeattleSeattleSeattle
Yesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler TerraceYesler Terrace
Elliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott BayElliott Bay
999999999999999999
Harborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview HospitalHarborview Hospital
U S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina HospitalU S Marina Hospital
Mason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason HospitalMason Hospital
Union DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotUnion DepotKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street StationKing Street Station
Seattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle UniversitySeattle University
1ST
4THALA
SKAN
WAY
BO
RE
N
E MADISON
RAIN
IER
AVE S
S 1
ST
STE
WART
YESLER WAY
I-5
RAMP
I-90
© 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping © 1993 DeLorme Mapping
Seattlesection
WSDOTsection
Alaskan Way ViaductAlaskan Way Viaduct Alaskan Way ViaductAlaskan Way Viaduct
Alaskan Way ViaductAlaskan Way Viaduct
Seattlesection
WSDOTsection
Alaskan Way ViaductAlaskan Way Viaduct
Seattle Section
Alaskan Way ViaductAlaskan Way Viaduct
WSDOT Section
Seismic Vulnerability ConcernsSeismic Vulnerability Concerns
• Loma Prieta earthquake
M=7.1
100 km south of Oakland
• Cypress Structure
Highway 17 in Oakland
Double-deck reinforced concrete structure
Similar age
Similar design requirements
Pile supported due to soft surficial soils
Cypress StructureCypress Structure Cypress StructureCypress Structure
Alaskan Way Viaduct InvestigationsAlaskan Way Viaduct Investigations
• 1990 WSDOT internal review
• 1991-92 UW review
• 1993-95 UW/WSDOT investigation
• 1995-96 WSDOT seawall investigation
UW / WSDOT InvestigationUW / WSDOT Investigation
WSDOT Seawall InvestigationWSDOT Seawall Investigation
• Structural Engineering Aspects
• Geotechnical Engineering Aspects
• Seawall performance
• Effects on AWV
• Remediation strategies
Geotechnical Engineering InvestigationGeotechnical Engineering Investigation
• Site characterization
• Seismic hazard analysis
• Ground response analyses
• Foundation response characteristics
• Evaluation of liquefaction hazards
Site CharacterizationSite Characterization
• Review of historical records
• Review of previous subsurface investigations
• Supplemental subsurface investigations
- SPT
- CPT
- Seismic cone
- Downhole seismic
Seattle, 1888Seattle, 1888Historical RecordsHistorical Records
Seattle, 1884Seattle, 1884Historical RecordsHistorical Records
Lake Washington
Yesler
I-5
Looking NW fromBeacon Hill
Looking north along waterfront
Looking eastfrom Elliot Bay
Tideflats, 1896
TideflatTideflat Reclamation Reclamation
TideflatTideflat Reclamation Reclamation Railroad Avenue - 1920sRailroad Avenue - 1920s
Railroad Avenue - 1920sRailroad Avenue - 1920s Seattle SeawallSeattle Seawall
• 12,000 lb/ft lateral thrust
• Four different wall types
- Timber pile-supported relieving platform (2)
- Pile-supported concrete wall
- Fill and rip rap wall
• Total cost: $1.4 million
Type B Seawall SectionType B Seawall Section Type B Seawall SectionType B Seawall Section
Precast Section
Master Pile
Timber Relieving Platform
BatterPiles (12)
VerticalPiles (6)
Pile/Platform ConnectionPile/Platform Connection Seawall ConstructionSeawall Construction
Seawall ConstructionSeawall Construction
40
50
60
30
20
10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
-150
1601501401301201101009080706050403020100100110120130150160170180190200 210220230240250260250260270280290300310300310320330340350360 90 80 70 60 50 40 30 20 10
B-7
105/9"
1/24"
1/18"
1/40"
14
3
4
2
8
53
45
49
65
30
92/10"
97/9"
50
8
6
6
6
3
2
5
13
2
1
53/6"65/6"
4750/2"
25
H-4-93
MUDLINE
VIC. BENT 75
VIADUCT STA 70+45
SEAWALL STA. 5+30
60' S. CL SENECA
DAMES AND MOORE SAMPLER
WT.= 320 lb STROKE 30"
?
?
TILL
50/3"(ON ROCK)0
50/3"
50/5"
50/4"
B-2-81
?
WATER LINE
CITY OF SEATTLE DATUM
TILL
CL
140
H-34-96
4
8
2
0
0
50/3"
65
18
24
36
370380
?
?
DATE
SCALE VERT.
HORIZ.
SHEET OF
DRAWN BY
JOB S.R. C.S.
WASHINGTON STATE
DEPARTMENT OF TRANSPORTATION
MATERIALS BRANCHMATERIALS ENGINEER
TRANSPORTATION COMMISSION
40
50
60
30
20
10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
-150
D. C. JACKSON
FEB. 1996
1"=40'
1"=40'
LSH
MS-2494 99 1102
ALASKAN WAY VIADUCT
ALASKAN WAY VIADUCT
FIGURE 4: SECTION C - C'
1 2
B-2, B-7 AND B-8
Type A Seawall SectionType A Seawall Section
40
50
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
-150
-160
250240230220210200190180170160150140130120110100908070605040302010010203040
CL
5060708090100110120130140150160170180190200210220230240250260270280290300310320330340350360370380
60
70
1.25:1
70
60
50
40
30
-90
-100
-110
-120
-130
-140
-150
0
0788737
69
4084927850/4"
78/6"
B-7
Boring Projected
70' South
B-2
R-3 R-4-72-72
Projected270' NW
6541/6"012114450/4"50/3"50/6"4788/11"50/5"758950/6"
50/4"
9
342
1/18"
43765
H-3-93
Projected
310' NW
73
8516100+
R-16-82
Projected 115' NW
55125510100+
R-17-82
Projected175' NW
DATE
SCALE VERT.
HORIZ.
SHEET OF
DRAWN BY
JOB S.R. C.S.
WASHINGTON STATE
DEPARTMENT OF TRANSPORTATION
MATERIALS BRANCHMATERIALS ENGINEER
TRANSPORTATION COMMISSION
CITY OF SEATTLE DATUM
ALASKAN WAY VIADUCT
D. C. JACKSON
1"=40'
1"=40'
JAN. 1996
22
112
1328134
6351/6"5160/6"84/6"
R-5-68
Projected 15' SE
171491612114/10"65/6"6974100/2"
R-6-68
Projected 300' NW
01/60"42/18"1/12"1/24"
H-35-96
Hole terminateddue to
contaminated soil? ??
??
TILL
TILL
TILL
TILL
Projected 105' NW
CPT38
VIC. BENT 96
VIADUCT STA. 85+46
30' SOUTH OF INTERSECTIONWITH CL OF YESLER WAY
MS-2494 99 1102
500
Qc (tsf)
ALASKAN WAY VIADUCT
WATER LINE
FIGURE 5: SECTION D - D'
1 1
LSH
Pile-Supported Concrete Wall SectionPile-Supported Concrete Wall Section
40
50
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
-140
-150
-160
250240230220210200190180170160150140130120110100908070605040302010010203040
CL
5060708090100110120130140150160170180190200210220230240250260270280290300310320330340350360370380
60
70
1.25:1
70
60
50
40
30
-90
-100
-110
-120
-130
-140
-150
0
0788737
69
4084927850/4"
78/6"
B-7 B-2
R-3 R-4-72-72
Projected117' NW
6541/6"012114450/4"50/3"50/6"4788/11"50/5"758950/6"
50/4"
9
342
1/18"
43765
H-3-93
Projected157' NW
73
8516100+
R-16-82
Projected
551255
10100+
R-17-82
Projected
DATE
SCALE VERT.
HORIZ.
SHEET OF
DRAWN BY
JOB S.R. C.S.
WASHINGTON STATE
DEPARTMENT OF TRANSPORTATION
MATERIALS BRANCHMATERIALS ENGINEER
TRANSPORTATION COMMISSION
CITY OF SEATTLE DATUM
ALASKAN WAY VIADUCT
D. C. JACKSON
1"=40'
1"=40'
FEB. 1996
FILL2
22
112
1328134
6351/6"
5160/6"84/6"
R-5-68
Projected
85' SE
R-6-68
171491612114/10"65/6"6974100/2"
Projected
147' NW
Projected154' NW
H-35-96
Projected 38' SE25' SE
0
42/18"1/12"1/24"
1/60"
20
10
Hole terminateddue to
contaminated soil
MS-2494 99 1102
22' NW
?
?
?
??
TILL
TILLTILL
TILL
CPT38
VIC. BENT 97
VIADUCT STA. 86+15
200' SOUTH OF CL
OF YESLER WAY
500
Qc (tsf)
WATER LINE
'
ALASKAN WAY VIADUCT1 1
LSH
FIGURE 6: SECTION E - E'
Fill and Rip Rap Wall SectionFill and Rip Rap Wall Section
Alaskan Way ViaductAlaskan Way Viaduct
• History
-Originally intended as downtown bypass
- Design began in 1948, bids opened 1949
- Seattle section opened April 4, 1953
- WSDOT section opened Sept 3, 1959
- Seneca Street off-ramp opened 1961
- Columbia Street on-ramp opened 1966
• Facts
- 7,600 ft long
- 58,867 yards of concrete, 7,460 tons of rebar
- 171,410 ft of piling
36 ft
22 ft
70 ft
Typical Elevation (WSDOT Section)Typical Elevation (WSDOT Section)
57 ft57 ft
36 ft
22 ft
47 ft
Typical Interior Bent (WSDOT Section)Typical Interior Bent (WSDOT Section)FoundationsFoundations
WSDOT Section Seattle Section
2’
2.5’
FoundationsFoundations
Seattle Section WSDOT Section
17’
13.5’
12’
12’
3.5’
Seattle Section WSDOT Section
Originally intended to useonly H-piles
Contractor requestedchange
Steel piles - 48 tons
All other piles - 40 tons
Originally intended to useonly H-piles
Contractor requestedchange
Steel piles - 48 tons
All other piles - 40 tons
Seattle Section WSDOT Section
S. Massachusetts St.
Columbia St.
University S
t.
Yesler Way
S. Royal Brougham
Way
Bla
ncha
rdSubsurfaceSubsurface
DataData
Ste
war
t St.
50 shallow borings by SEDin 1948
17 deep borings by WSDOHin mid-1950s
Various borings by others
8 borings with SPT
16 CPT soundings withseismic cone
2 deep borings with downholeseismic
100
50
0
-50
-100
-150
Ele
va
ion
(ft
)
Ele
vation (
ft)
100
0
50
-50
-100
-150
Waterfront FillTideflat Deposit
Till
1000 ft
Bla
nch
ard
Ste
wa
rt
Un
ive
rsity
Ye
sle
r
Ma
ssa
ch
use
tts
Ro
ya
l B
rou
gh
am
Subsurface ProfileSubsurface Profile
0
50
100
150
0 10 20 30 40 50
Existing Data
SupplementalSubsurfaceInvestigation
Standard Penetration Resistance (blows/ft)D
ep
th (
ft)
Uncorrected SPT ResistanceUncorrected SPT Resistance
-0.5
0
0.5
0 20 40 60 80
Input MotionsInput Motions
• PSHA (10% in 50 yrs = 475-year return period)
- Peak acceleration
- Spectral velocities
- Bracketed duration
• Design-level response spectrum
• Quasi-synthetic time histories
• Deconvolution to produce 3 “bedrock” motions
Accele
ration (
g)
Time (sec) 0 20 30 40 5010
Time (sec)
0.6
0.0
-0.6
0.6
0.0
-0.6
0.6
0.0
-0.6
Acce
lera
tion (
g)
Acce
lera
tion (
g)
Acce
lera
tion (
g)
10 ft soft soil
50 ft soft soil
100 ft soft soil
Ground Surface MotionsGround Surface Motions
Liquefaction SusceptibilityLiquefaction Susceptibility
• Historical evidence
- Sand boils in 1949 and 1965
- Broken pipes in 1949 and 1965
- Lateral movements in 1965
• Construction techniques
- Hydraulic filling
- Dumping through water
• Previous investigations
- Mabey and Youd (1991)
- Grant et al. (1992)
Scenario Earthquake #1 Scenario Earthquake #2
M 7.5 7.5
a max 0.30 g 0.15 g
Displacement (in.)
>100 14 - 100
84 - 100 6 - 48
45 - 84 2 - 12
10 - 45 0 - 4
Little liquefaction susceptibility but in areas with
steep slopes. Liquefaction is unlikely, but if it
were to occur, large displacements are
possible.
No displacement likely due to liquefaction.
Mabey and Youd (1991)
0
10
20
0 5 10 15 20 25 30 35
Depth
(ft)
(N )1 60
(N )1 60required to prevent
liquefaction
Liquefaction EvaluationLiquefaction Evaluation
Standard Penetration Test
0
10
20
30
40
50
0 5 10 15 20 25 30 35
(N )1 60
Depth
(ft)
(N )1 60
required to preventliquefaction
Liquefaction EvaluationLiquefaction Evaluation
Standard Penetration Test
0
10
20
30
40
50
60
70
0 0.25 0.5 0.75 1 1.25
FS L
Depth
(ft
)
SPT-Based Factor of SafetySPT-Based Factor of Safety
0
10
20
0 5 10 15 20 25 30 35
Depth
(ft)
(N )1 60
Design-levelground motion
Liquefaction EvaluationLiquefaction EvaluationComparison with 1965 observations
Depth
(ft)
(N )1 60
0
10
20
0 5 10 15 20 25 30 35
Design-levelground motion
1965groundmotion
Liquefaction EvaluationLiquefaction EvaluationComparison with 1965 observations
0
10
20
30
40
50
0 5 10 15 20 25 30 35
(N )1 60
Depth
(ft)
Design-levelground motion
Liquefaction EvaluationLiquefaction EvaluationComparison with 1965 observations
0
10
20
30
40
50
0 5 10 15 20 25 30 35
(N )1 60
Depth
(ft)
Design-levelground motion
1965groundmotion
Liquefaction EvaluationLiquefaction EvaluationComparison with 1965 observations
0
10
20
30
40
50
60
70
0 1 2 3
FS L
De
pth
(ft
)
SPT-Based Factor of SafetySPT-Based Factor of Safety
1965groundmotion
Effects of LiquefactionEffects of Liquefaction
• Sand boils - expected over most of length
• Post-earthquake settlement
- Up to 1” in fill above water table
- Up to 25” in soft, saturated soils
• Vertical pile movement
- Tip capacity reached at r = 0.6
- Tips of southernmost piles in liquefiable soil
• Lateral pile movement
- Depends on lateral soil movement
- 10”-12” expected to cause bending failure
- Lateral soil movement depends on seawall movement
u
All movements variable due to variability of soil profile
Seawall InvestigationSeawall Investigation
• Transverse profile characterization
- 5 additional borings (2 offshore)
- 3 additional CPT soundings
• Seawall structure characterization
- Member sizes
- Member properties
- Connection strengths
• Computational model
- Soil
- Seawall
- Soil-seawall interaction
Estimation of permanent deformations due to liquefaction
FLAC
FLACFLAC
Fast Lagrangian Analysis of Continua
• Explicit finite difference code
• Large-strain capabilities
• Several soil constitutive models
• Structural elements (beams, piles, cables)
• Interface elements (normal and shear)
• Coupled stress-deformation and flow capabilities
• Incremental construction modeling
• Graphical display of results
• Dynamic option
• Creep option
• FISH programming language
Alaskan Way Viaduct
Type B Wall ModelType B Wall Model
Entire Section
Alaskan Way Viaduct
Type B Wall ModelType B Wall Model
Entire Section
3400 soil elements610 structural elements
Type B Wall ModelType B Wall Model
Precast Section
Master Pile
Timber Relieving Platform
BatterPiles (12)
VerticalPiles (6)
Type B Wall ModelType B Wall Model Type B WallType B Wall
Beforeliquefaction
Type B WallType B Wall
Duringliquefaction
Type B WallType B Wall
Afterliquefaction
Fill and Rip Rap WallFill and Rip Rap Wall
Beforeliquefaction
Fill and Rip Rap WallFill and Rip Rap Wall
Duringliquefaction
Fill and Rip Rap WallFill and Rip Rap Wall
Afterliquefaction
Columbia St.
Madison St.
University S
t.
S. Washington St.
Zones of Large Lateral MovementsZones of Large Lateral Movements
Structural Aspects of Seismic VulnerabilityStructural Aspects of Seismic Vulnerability
• Dynamic Response Spectrum Analyses
• Nonlinear “Pushover” Analyses
• Investigated capacities and demands for:
- Flexure (beams and columns)
- Shear (beams and columns)
- Splices
- Joints
- Pile Caps
Capacity/Demand RatiosCapacity/Demand Ratios
3.12
4.35
0.62
0.49 0.56
0.69
1.96
2.15
Exterior Frame - Column Flexure
Capacity/Demand RatiosCapacity/Demand Ratios
1.91
9.87
0.60
0.46 0.53
0.67
1.88
1.17
Interior Frame - Column Flexure
Capacity/Demand RatiosCapacity/Demand Ratios
Longitudinal Frame - Column Flexure
3.57
0.61
0.66
1.70
1.65 3.18 2.72
1.971.58
0.71
0.92
0.43
0.50
0.43
0.50
0.69
Capacity/Demand RatiosCapacity/Demand Ratios
0.02
0.10 0.12
0.03
Splices
InteriorFrame
ExteriorFrame
Pile CapsPile Caps
FlexuralCapacity - OK
Shear Capacity -Insufficient (C/D= 0.3 - 0.6)
AnchorageCapacity -Insufficient
Joint Capacity -Insufficient (C/D= 0.6 - 1.2)
Summary of Structural VulnerabilitySummary of Structural Vulnerability
• Lower-level splices highly vulnerable
• Joints highly vulnerable
• Columns - shear capacity marginal
• Footings - vulnerable to brittle failure
• Special sections require additional investigation
- Outrigger bents
- On/off ramp sections
Summary of Structural VulnerabilitySummary of Structural Vulnerability
• Lower-level splices highly vulnerable
• Joints highly vulnerable
• Columns - shear capacity marginal
• Footings - vulnerable to brittle failure
• Special sections require additional investigation
- Outrigger bents
- On/off ramp sections
Effects of liquefaction-induced lateral soilmovements will dominate effects of shaking
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