1. DISCOVERY IN THE ENGINEERING SIDE
OF SEISMIC MONITORING
Bob Nigbor,
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. Samoa Bridge Strong Motion Infrastructure
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
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