GVDA NEES Field Facilities: A Resource for Earthquake Engineering (and Seismology) Research and Practice Bob Nigbor UCLA

GVDA

3 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

GVDA 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

GVDA Large unidirectional shaker

GVDA kip Linear Shaker

GVDA High Performance Mobile Network

GVDA Mobile Command Center  Originally data acquisition trailer 8’ x 16’  Upgraded to self propelled vehicle 2003 Chevy Crew cab 8’ x 15’ van body

GVDA Wireless Network Wireless Backbone Workgroup Access points Sensor stations Data Concentrator

GVDA Cone Penetration Testing (CPT) Truck  Vendor: Hogentogler, Inc.  Site characterization Tip resistance Sleeve resistance Inclination Pore pressure Geophone for shear wave velocity

GVDA 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 Drive shoe Probe Triaxial accelerometer Cable

GVDA Q330 RSA Installation

GVDA Shaker RSA Q330 To Command Center Monitoring Concept

GVDA 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  ????

GVDA D 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

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

GVDA Location of Garner Valley Digital Array (GVDA) and Wildlife Array (WLA)

GVDA GVDA Permanent Array

GVDA GVDA Permanent Surface Array

GVDA 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)

GVDA SFSI Test Structure at GVDA 4mx4mx4m 35 tons Structural stiffness~soil 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

GVDA F4: Natural Earthquake Native Soil Water Table 0-3 m Pore Pressure Accelerometer F1 F2 F3 5m F1 : Permanent Shaker F2 : Shaker F3 : Shaker SFSI Structure Testing

GVDA Measured Properties

GVDA Uni-axial AccelerometerTri-axial Accelerometer Rotation SensorDisplacement Transducer Pressure Cell and Sensor Instrumentation

GVDA 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

GVDA 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.