Simulation in Shaking

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Simulation in Shaking
Table Tests of Soil-Structure
Interaction Effect
KONAGAI Laboratory
IIS, University of Tokyo
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World largest shake table
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World largest shake table
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Energy used up within a structure
Super-structure
Structure pushes back the soil
Wave dissipation
Wave dissipation
Influx of Energy
Efflux of energy
Input seismic motion
Concept of Soil-Structure Interaction
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Kinematic interaction andInertia interaction
p
f
p
x
u
r
u
f
u
s
u
f
u
s













inertia interaction
kinematic interaction
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Simulation of Soil-Structure Interaction Effect
Force transducers
p
Shaking table
DSP or Analog Circuits
u
r
Energy used up within structure
Efflux
Influx
-

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Beam Analogy for Soil-Pile group Interaction
Analysis
BASPIA
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Kinematic Interaction
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Variation of
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Inertia Interaction
u
r
Function of
Active Pile Length
P

M
K

C

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Spring constant K
Function of
Active Pile Length
P

M
K

C

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Radiation Damping C
Function of
Active Pile Length
P

M
K

C
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Whats Radiation Damping?
A jelly-like soft soil model of urethane with an
upright and flexible gelatin plate sandwiched in
its interior was prepared in an acrylic box. An
impulse was then applied to a foundation resting
on or embedded in the soil model. Since
photo-elastic sensitivity of gelatin, when
compared with that of urethane, is extremely
high, cross sections of sharp wave fronts induced
by the impulse and transmitted through the 3D
soil model are clearly visualized on the inner
plane of gelatin through a polariscope
arrangement
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Variations of
p

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APPROXIMATION
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Technical problems
Delay D t
Cancellation of time delay effect
K
M
C
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Slip of Rigid Block on Mat Foundation

• Simple phenomenon to simulate

Rigid block radius 7m height 2m
Mat foundation radius 11 m Height 1.6 m
Half space of soil shear wave velocity 100
m/sec Poissons ratio 0.5
Influx Efflux of energy
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Rigid block (6.75 kgf)
Stiff upright beam
50mm
Shaking table
24cm
Shaking table
Strain gages
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Measured displacements
u (no interaction)
Du (no interaction)
Du distance that the block slipped
Du (with interaction)
(with interaction)
Shaking table
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Numerical Simulation of Du
No interaction
With interaction
Thick lineobserved broken linesimulated
Du
Shaking table
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Without interaction
Influx of energy
Energy loss through friction
Kinematic energy
friction
Energy influx
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Influx and Efflux of energy
Influx of energy
Energy loss through friction
Efflux of energy
Kinematic energy
Energy loss through friction
Influx
Efflux
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Prototype structure
Shaking Table
K
M
C
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Free-field ground motion
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Model Experiment
K
M
C
Shaking Table
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Energy Influx and Efflux
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New Shaking Table at IIS