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Gain insights into seismic monitoring discoveries in earthquake engineering through enhanced measurements and complete monitoring, utilizing existing infrastructure and data to study structural behaviors, crack movements, and environmental impacts.
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DISCOVERY IN THE ENGINEERING SIDE OF SEISMIC MONITORING Bob Nigbor, NEES@UCLA SITS 2013, Albuquerque
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
Samoa Bridge, Eureka, CA SITS 2013, Albuquerque
Accelerometer Recording Samoa Bridge Strong Motion Infrastructure SITS 2013, Albuquerque
Active & Passive Testing 6/6/13 SITS 2013, Albuquerque
Watts Towers Monitoring SITS 2013, Albuquerque
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
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
Acceleration & Tilt SITS 2013, Albuquerque
Dynamic Wind (5Hz) SITS 2013, Albuquerque
Crack Displacement SITS 2013, Albuquerque
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
Temperature variation of first mode in N-S direction NEES at Watts Towers, 4/23/2013
North Tilt and Temperature vs. Time in Hours NEES at Watts Towers, 4/23/2013
Crack Movement SITS 2013, Albuquerque
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