1 OpenSeesPL – 3D Pile-Ground Interaction Jinchi Lu University of California, San Diego [email protected]Ahmed Elgamal Zhaohui Yang Thomas Shantz September 3, 2010 Outline Soil constitutive models Solid-fluid fully-coupled elements OpenSeesPL graphical user interface Examples of using OpenSeesPL Ongoing research projects
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OpenSeesPL – 3D Pile-Ground Interactionopensees.berkeley.edu/.../workshops/OpenSeesDays2010/B7_OpenSeesPL.pdfOpenSeesPL – 3D Pile-Ground Interaction Jinchi Lu ... liquefaction
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a) 140-element mesh b) 260-element mesh c) 500-element mesh
−0.2
−0.1
0
0.1
0.2
Acc
eler
atio
n (g
) Base excitation
0 2 4 6 8 10 12
0
0.5
1
Time (sec)
Dis
plac
emen
t (m
) Pile head longitudinal displacement
140−element mesh260−element mesh500−element mesh
−20
−10
0
10
20
2m depth
0 2 4 6 8 10 12−20
0
20
40
60
Exc
ess
pore
pre
ssur
e (k
Pa)
6m depth
Time (sec)
Excess pore pressure time histories in the free-field (500-element mesh)
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25
Schematic view Of stone column or pile layout
Example 2: Stone Column Ground Modification
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14
4 x 8 4.5 ft Diameter Hollow RC Piles
2D (long) x 2.15D (trans) pile spacing
Dumbarton Bridge16
m 1
4 m
27
m
Pier 23
Example 3: Large Pile Group
8 x 4 Pile Group in Half Mesh
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C (kPa)345874
G (MPa)193560
0 0.02 0.04 0.06 0.08 0.1 0.120
0.5
1
1.5
2
2.5
3x 10
4
Pile cap displacement (m)
Pile
gro
up s
hear
load
(kN
)
Applied Loads
1. Bridge Own weight
2. Pushover analysis (1 g)
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Front Corner PileMoment =1.35 of inner pile
Case of force only
Axial force
Axial force
Down‐drag
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For the employed cohesive soil scenario:
- Corner piles are most vulnerable- Edge piles carry much more axial load than inner piles- Axial response and skin friction (t-z springs) may play a critical role
- Pile tensile forces may be quite significant and affect RC response (connection to pile-cap, reduction in confinement)
Summary for Pile Group Study
Machine: Teragrid IA-64
Parallel Computing on Supercomputer
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Ongoing Project: OpenSeesPBEEPerformance-Based Earthquake Engineering (PBEE) Analysis of Bridge Systems - with Prof. Mackie (Univ. of Central Florida)
Bridge and Ground Model
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Input Motions
Concurrent Execution for Multiple Records
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Performance Group (PG) Quantities
Report Generator
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Unit Costs
PBEE Outcome: Repair Cost
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30% of original cost
Total Repair Cost Ratio
Ongoing Project: Deep Soil MixingJoint project with UC Davis (Prof. Boulanger) and Oregon State Univ. (Prof. Ashford)