NEES Field Facilities: A Resource for Earthquake Engineering (and Seismology) Research and Practice

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NEES Field Facilities A Resource for Earthquake
Engineering (and Seismology) Research and Practice

• Bob Nigbor
• UCLA

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(No Transcript)
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• nees_at_ucsb
• 3D Geotechnical Arrays at 2 permanent field sites
  in Southern California
• Soil-Foundation-Structure-Interaction (SFSI) Test
  Structure
• Real earthquake data
• Test bed for geotechnical and geophysical methods
• Location for active experiments in a
  well-characterized field setting

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• nees_at_ucla
• 3 large mobile building shakers
• Extensive field-deployable instrumentation system
• CPT truck for research applications
• Large-amplitude excitation of structures
• Field testing/monitoring of structures
• Site characterization and installation of
  subsurface sensors using CPT

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Large unidirectional shaker
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15kip Linear Shaker
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High Performance Mobile Network
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Mobile Command Center

• Originally data acquisition trailer
• 8 x 16
• Upgraded to self propelled vehicle
• 2003 Chevy Crew cab
• 8 x 15 van body

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Wireless Network
Data Concentrator
Sensor stations
Access points
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Cone Penetration Testing (CPT) Truck

• Vendor Hogentogler, Inc.
• Site characterization
• Tip resistance
• Sleeve resistance
• Inclination
• Pore pressure
• Geophone for shear wave velocity

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Retrievable Subsurface Accelerometer

• Insert with CPT truck
• Compatible with Q330 data loggers
• Retrievable with winch
• Silicon Designs MEMS triaxial accelerometer
• Downhole signal conditioning to reduce noise
  contamination
• Micro-controller for built in sensor intelligence

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RSA Installation
Q330
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Monitoring Concept
Shaker
To Command Center
Q330
RSA
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Opportunities

• Experimental modal analysis of buildings other
  structures
• Nonlinear excitation of structures
• Verification of computer models of structures
• Field verification of response modification
  devices (active passive control)
• Full-scale SFSI studies
• ????

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• nees_at_ucsb
• 3D Geotechnical Arrays at 2 permanent field sites
  in Southern California
• Soil-Foundation-Structure-Interaction (SFSI) Test
  Structure
• Real earthquake data for pure applied research
• Test bed for geotechnical and geophysical methods
• Location for active experiments in a
  well-characterized field setting

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Acknowledgements

• Principal Investigators are
• Les Youd, BYU
• Jamie Steidl, UCSB
• Bob Nigbor, USC
• UCSB (led by Jamie Steidl) operates the two sites

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Location of Garner Valley Digital Array (GVDA)
and Wildlife Array (WLA)
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GVDA Permanent Array
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GVDA Permanent Surface Array
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Upgraded Instrumentation

• 24-bit real-time dataloggers (Q330)
• On-site data concentrator computer (Antelope ORB)
• High-speed wireless data communications via
  HPWREN
• Concrete instrument building (instead of trailer)

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SFSI Test Structure at GVDA

• 4mx4mx4m
• 35 tons
• Structural stiffnesssoil stiffness
• Configurable bracing to modify stiffness
• Can add mass at roof
• 10 Hz fixed-base frequency without bracing, 15Hz
  with
• Can bolt large shakers from UCLA to roof

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SFSI Structure Testing
F2
F1 Permanent Shaker
F1
F3
F2 NEES_at_UCLA Shaker
Native Soil
5m
Water Table 0-3 m
Pore Pressure
F3 NEES_at_UTexas Shaker
5m
Accelerometer
F4 Natural Earthquake
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Measured Properties
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Instrumentation
Pressure Cell and Sensor
Uni-axial Accelerometer
Tri-axial Accelerometer
Rotation Sensor
Displacement Transducer
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SFSI Data System

• 24-bit resolution
• 1000 sps/channel maximum
• Real-time data output via TCP/IP
• Multiple remote clients can observe and record
  data

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Potential Research Uses

• Passive study of the effect of a structure upon
  ground shaking (What is Free-Field?).
• The existing GVDA array has recorded many small
  to moderate earthquakes, allowing detailed
  characterization of the site with no building.
  After addition of the 120-ton test building, it
  will be possible to study how the simple
  structure affects the earthquake ground motions
  at this simple site. Differences will be due to
  SFSI effects.
• Active study of liquefaction.
• Both the Wildlife and GVDA sites are on
  liquefiable soils, especially during the winter
  wet season. At both sites we will add concrete
  pads on which large shakers from the NEES
  University of Texas mobile shakers can be
  mounted. These shakers should be powerful enough
  to cause localized liquefaction. Data from such
  an experiment could then be used to verify
  predictive models of both liquefaction and ground
  shaking.
• Active study of SFSI physics.
• At GVDA, the reconfigurable test structure will
  have significant SFSI in the soft soil. The
  instrumentation can be used to measure structure
  and soil motion, soil pressures, and pore water
  pressures during active shaking of the structure
  by the UCLA NEES equipment. Such data will be
  invaluable for verification of predictive
  physics-based models of SFSI.