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

1. NEES Field Facilities: A Resource for Earthquake Engineering (and Seismology) Research and Practice Bob Nigbor UCLA GVDA-051906

2. GVDA-051906

3. nees@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 GVDA-051906

4. nees@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 GVDA-051906

5. Large unidirectional shaker GVDA-051906

6. 15kip Linear Shaker GVDA-051906

7. High Performance Mobile Network GVDA-051906

8. 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-051906

9. Workgroup Wireless Backbone Wireless Network Data Concentrator Sensor stations Access points GVDA-051906

10. Cone Penetration Testing (CPT) Truck • Vendor: Hogentogler, Inc. • Site characterization • Tip resistance • Sleeve resistance • Inclination • Pore pressure • Geophone for shear wave velocity GVDA-051906

11. Cable Driveshoe Probe Triaxial accelerometer 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 GVDA-051906

12. RSA Installation Q330 GVDA-051906

13. Monitoring Concept Shaker To Command Center Q330 RSA GVDA-051906

14. 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-051906

15. nees@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 GVDA-051906

16. Acknowledgements • Principal Investigators are: • Les Youd, BYU • Jamie Steidl, UCSB • Bob Nigbor, USC • UCSB (led by Jamie Steidl) operates the two sites GVDA-051906

17. Location of Garner Valley Digital Array (GVDA) and Wildlife Array (WLA) GVDA-051906

18. GVDA Permanent Array GVDA-051906

19. GVDA Permanent Surface Array GVDA-051906

20. 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-051906

21. 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-051906

22. SFSI Structure Testing F2 F1 : Permanent Shaker F1 F3 F2 : NEES@UCLA Shaker Native Soil 5m Water Table 0-3 m Pore Pressure F3 : NEES@UTexas Shaker 5m Accelerometer F4: Natural Earthquake GVDA-051906

23. Measured Properties GVDA-051906

24. Instrumentation Pressure Cell and Sensor Uni-axial Accelerometer Tri-axial Accelerometer GVDA-051906 Rotation Sensor Displacement Transducer

25. 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-051906

26. 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. GVDA-051906