Geotechnical and SSI Simulations -...
Transcript of Geotechnical and SSI Simulations -...
9/14/2008
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Geotechnical and SSI Simulations
Ahmed Elgamal
Jinchi Lu
Zhaohui Yang
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Yuyi Zhang, Joel P. Conte, Zhaohui Yang, Ahmed Elgamal, Jacobo Bielak, and Gabriel Acero, Two-
Dimensional Nonlinear Earthquake Response Analysis of a Bridge-Foundation-Ground System,
Earthquake Spectra, Volume 24, No. 2, pages 343–386, May 2008, Earthquake Engineering Research
Institute
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2-D Finite Element Model in OpenSeesProf. Joel Conte, Joint Research
• Plane strain condition
• 11,000 nodes and 10,900 elements; 20,000 DOF’s
• 370 beam-column elements
• 9,900 quadrilateral “soil” elements
• 590 zero-length elements3A. Elgamal Sept 2008
ZeroLength Element ZeroLength Element
Column
Beam
Gap & Hook
Beam
Gap & Hook
• Expansion joints: Zero-length elements with gap-hook material
Superstructure Joints
1/2” Expanded Joint
Filler All Around
Shear Key
5 #4 Rebars
per Key
Cap Beam
Superstructure
• Abutment joints: Zero-length elements with gap-hook material
ZeroLength Element ZeroLength Element
Column
Beam
Gap & Hook
Beam
Gap & Hook
1/2” Expanded Joint
Filler All Around
Shear Key
5 #4 Rebars
per Key
Cap Beam
Superstructure
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OpenSees 3D FE Model • 30,237 nodes
• 1,140/280 linear/nonlinear beam-column elements
• 81 linear shell elements
• 23,556 solid brick elements
• 1,806 zero-length elements
Transverse and Longitudinal Response
3D Spatial Configuration
Abutments
Pile Foundations
Ground
Three-Dimensional Seismic Response of Humboldt Bay
Bridge-Foundation-Ground System, A. Elgamal,
L. Yan, Z. Yang, and J. P. Conte, Journal of
Structural Engineering, Vol. 134, No. 7, July 1, 2008.
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Piers and Pile Groups (Fiber Discretization of Pier and Pile Cross-Sections)
(Prof. P. Fillippou)
Bilinear
Kent-Scott-Park model
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(1) Rock outcrop motion
Deconvolu
tion
Usin
g S
hake91
(2) Incident motion at the top of bedrock (2)
Pro
pagation
Usin
g S
hake91
(3) Incident motion at FE model base
Soil profile
Shear Wave Velocity (m/s)
Depth
(m
)
0 200 400 600 800 10000
40
80
120
160
200
240
Rock
profile
Measured
Model
Idealization
Definition of Seismic Excitation (Engineering Seismology)
Stage I
Stiff spring
Stage II
Equivalent
supporting force
Equivalent
earthquake forceDashpot
1σ ′
2σ ′
3σ ′
321 σσσ ′=′=′
Note: Tied node condition on lateral boundaries (shear beam concept) 7A. Elgamal Sept 2008
1 2 3
4
Elevation and Plan View
of Residual Deformation
(Scaling Factor = 50)
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Three-Dimensional Seismic Response of Humboldt Bay
Bridge-Foundation-Ground System, A. Elgamal,
L. Yan, Z. Yang, and J. P. Conte, Journal of Structural
Engineering, Vol. 134, No. 7, July 1, 2008.
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Numerical Analysis
Permanent Deformation of Bridge, Foundations, and Abutments
Original position Final position with residual deformation
#1 Pier
& pile
group
#2 Pier
& pile
group
#3 Pier
& pile
group
#4 Pier
& pile
group
#5 Pier
& pile
group
#6 Pier
& pile
group
#7 Pier
& pile
group
#8 Pier
& pile
groupLeft
abutment
Right
abutment
Original position
Final position with residual deformation
(a) Elevation view (exaggerated scale by a factor of 50)
(b) Plan view (exaggerated scale by a factor of 150)
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Shallow Foundation Settlement due to Liquefaction
(Scale factor for deformed meshes: 10)
Untreated case
Treated by compaction and high permeability
Treated by stone columns
0 20 40 60 80 100 120 140 160 180
−0.25
−0.2
−0.15
−0.1
−0.05
0
Time (sec)
Ver
tical
dis
plac
emen
t (m
) Medium Sand (LMS) Dense Gravel (LDG)Stone Column (LSC)
Foundation settlement time histories
0 10 20 30 40 50 60 70 80 90 100−0.2
−0.15
−0.1
−0.05
0
0.05
0.1
0.15
0.2
Time (sec)
Accele
ration (
g)
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US-Japan Cooperative Research (2003-2005)
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1.8m high, UCSD Shake table tests (Prof. Dobry, RPI Test Setup
Laminar container provided by Prof. Scott Ashford, UCSD
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Experiment Preparation
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UCSD Shake table test
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Shaking Table Tests: US-Japan Research (NSF, NIED, PEER, CALTRANS)
5m height: Liquefaction-Induced lateral Spreading Effects on Piles (NIED, Tsukuba)
Professor Kohji Tokimatsu, Dr. Masayoshi Sato, and Dr. Akio Abe
NIED, Tsukuba, Japan
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Before After
1m of Lateral Spreading ( > 3 pile diameters)
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Gravel Drain/Stone column Ground Modification
a) Isometric view
b) Pile head close-up
Finite element mesh for the 3x3 pile group. 26A. Elgamal Sept 2008
User Interface for Pile-ground systems
http://cyclic.ucsd.edu/openseespl
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0
0.05
0.1
0.15
0.2
0.25
0.3
2 3 4 5 6 7 8
Spacing (xD)
Pile h
ead
defl
ecti
on
(in
) 3x3 pile group
Single pile
Pile group displacement of the 3x3 pile group (for
different spacing) and the single pile under lateral
loading.
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OpenSees Computations through Graphical Interface OpenSeesPL
Spacing = 2D
Spacing = 3D28A. Elgamal Sept 2008
OpenSees Computations through Graphical Interface OpenSeesPL
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Spacing = 4D
Spacing = 5D29A. Elgamal Sept 2008
OpenSees Computations through Graphical Interface OpenSeesPL
Spacing = 6D
Spacing = 7D30A. Elgamal Sept 2008
OpenSees Computations through Graphical Interface OpenSeesPL
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Spacing = 8D
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OpenSees Computations through Graphical Interface OpenSeesPL
Chapter 6 Examples
6.1 Example 1: Linear Pile in Rigid Ground
6.2 Example 2: Linear Pile in Loose Sand
6.3 Example 3: Linear Pile in Medium Sand
6.4 Example 4: Nonlinear Pile in Linear Soil
6.5 Example 5: Saturated Medium Sand
6.6 Example 6: Stone Columns
6.7 Example 7: Pile in Sloping Ground
Appendix A Benchmark Linear Finite Element Analysis of Laterally Loaded Single Pile
Using OpenSees & Comparison with Analytical Solution
Appendix B Finite Element Analysis of Arkansas Test Series Pile #2 Using Opensees
(with LPILE Comparison)
Appendix C Finite Element Analysis of Standard CalTrans 16" CIDH Pile Using
Opensees for General Comparison with LPILE (with Default P-Y Multiplier = 1.0)
Appendix D Finite Element Analysis of Caltrans 42" CIDH Pile Using OpenSees for
General Comparison with LPILE (with Default P-Y Multiplier = 1.0)
Appendix E Finite Element Analysis of Standard CalTrans 16" CIDH Pile Subjected to
Axial Load
Appendix F Moment-Curvature Analysis of Circular Nonlinear RC Beam (Fiber
Section)
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OpenSeesPL Manual Examples
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl
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OpenSeesPL: http://cyclic.ucsd.edu/openseespl