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DISCOVERY IN THE ENGINEERING SIDE OF SEISMIC MONITORING

DISCOVERY IN THE ENGINEERING SIDE OF SEISMIC MONITORING. Bob Nigbor, NEES@UCLA. Discovery from data IS important in earthquake engineering.

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DISCOVERY IN THE ENGINEERING SIDE OF SEISMIC MONITORING

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  1. DISCOVERY IN THE ENGINEERING SIDE OF SEISMIC MONITORING Bob Nigbor, NEES@UCLA SITS 2013, Albuquerque

  2. Discovery from data IS important in earthquake engineering. • There is much to discover about structural behavior from better measurements and more complete monitoring, including different time scales, length scales, and metrics. • Lessons learned from Earthscope, hi-res seismic exploration, and decades of continuous recording of ground motions can be applied to experimental study of the “engineering layer” • The existing strong-motion infrastructure should be leveraged to provide better measurements SITS 2013, Albuquerque

  3. Samoa Bridge, Eureka, CA SITS 2013, Albuquerque

  4. Accelerometer Recording Samoa Bridge Strong Motion Infrastructure SITS 2013, Albuquerque

  5. SITS 2013, Albuquerque

  6. SITS 2013, Albuquerque

  7. SITS 2013, Albuquerque

  8. SITS 2013, Albuquerque

  9. Active & Passive Testing 6/6/13 SITS 2013, Albuquerque

  10. SITS 2013, Albuquerque

  11. SITS 2013, Albuquerque

  12. Watts Towers Monitoring SITS 2013, Albuquerque

  13. SITS 2013, Albuquerque

  14. Repair & Preservation of Watts Towers by LA County Museum of Art • What is causing cracking? • Earthquakes • Wind • Temperature • Differential temperature (sunlight) • Can dominant cause be mitigated? SITS 2013, Albuquerque

  15. NSF-funded Monitoring by NEES@UCLA (Taciroglu PI) • Acceleration • Tilt (AGI, microradian precision) • Temperature • Static & dynamic wind • Crack displacement • Others in future • Continuous data recording to capture different time scales SITS 2013, Albuquerque

  16. Acceleration & Tilt SITS 2013, Albuquerque

  17. Dynamic Wind (5Hz) SITS 2013, Albuquerque

  18. Crack Displacement SITS 2013, Albuquerque

  19. Frequencies (modes) of the main tower are at 2.2, 3.7, 6.5 Hz in the N-S direction. Vibration is complex in E-W direction due to coupling with other towers. NEES at Watts Towers, 4/23/2013

  20. Temperature variation of first mode in N-S direction NEES at Watts Towers, 4/23/2013

  21. North Tilt and Temperature vs. Time in Hours NEES at Watts Towers, 4/23/2013

  22. Crack Movement SITS 2013, Albuquerque

  23. Monitoring Discoveries So Far • 4 months of monitoring shows importance of different time scales and different measurements • Thermal effects govern • Strong thermal effect on stiffness (frequency) is interesting • Still waiting for earthquake & strong Santa Ana winds SITS 2013, Albuquerque

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