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Update on Millikan Library Research

Update on Millikan Library Research

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Update on Millikan Library Research

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  1. Update on Millikan Library Research John Clinton Case Bradford V 20 May 2003 Structural Monitoring Group Meeting

  2. Recent Work: • Movies • Hysterisis Plots • Transfer Functions • ModeShape Fitting

  3. Movies • 3 Recorded Data sets from USGS array • M3.8 April ‘98 Alhambra @ 7km • M4.8 Sept ’01 Yorba Linda @ 41km • M5.4 Feb ’03 Big Bear @ 120km Any others - M5.1Anza ‘01, M5.1Big Bear ‘01, Hector Mines ’99, local earthquakes?

  4. 22 Feb 03 Big Bear M5.4 at 120km Primarily 1st Mode resonance in both E-W and N-S directions Yorba Linda event similar – Basin waves dominate ground motion. Ref: www.ecf.caltech.edu/~jclinton/research

  5. 26 Apr 98 Alhambra M3.8 at 7km • small, local earthquake • simple short period pulse as main energy input • little excitation of basin waves • initially 2nd EW mode excited. After ~15s, slow emergence of 1st mode EW resonance.

  6. 26 Apr 98 Alhambra M3.8 at 7km 1st mode response NS 2nd mode response EW At initial S-wave pulse

  7. 26 Apr 98 Alhambra M3.8 at 7km 1st mode response NS 1st mode response EW About 15s after initial S-wave

  8. Time-Series for GSA and Millikan USGS Array (EW Channels, Displacement) No 2nd mode on 8,9 Floors 1st mode only appears later (long period excitation at GSA?)

  9. Hysterisis Plots • Attempting to recreate bi-linear stiffnesses Prof. Iwan showed last time • Same method – plot relative inter-floor displacement versus force of floors above • Problem: • No bilinear stiffnesses • No damping in real data, lots in forced vibrations

  10. 22 Feb 03 Big Bear M5.4 at 120km • EW channels • note: little or no `loop’ • also no change in stiffness • removing part of displacement due to tilt may change shape, but will not affect damping

  11. 22 Feb 03 Big Bear EW Channels Forced Vibration

  12. 22 Feb 03 Big Bear NS Channels Forced Vibration

  13. Transfer Functions • Utilise new data for old method • Old Method: SDOF * GSA = MIK? • New Data: • USGS array for MIK • CRP for GSA

  14. Yorba Linda Event MIK (9th Floor) Roof USGS EW NS

  15. Yorba Linda Event MIK (9th Floor) length of USGS record vs full length of excitation EW NS

  16. Yorba Linda Event 1st Floor 5th Floor Roof EW NS

  17. Alhambra Event 1st Floor 5th Floor Roof EW NS

  18. Alhambra Event – 2nd Mode Modeling 5th Floor 1st Mode EW 5th Floor 2nd Mode EW EW NS

  19. Miscellaneous Notes • Triggering and timing on USGS • Missing Data • Fixed USGS FBAs? • PWP meters? • ETABS model or Millikan in near future

  20. Maybe some CRP noise levels if time…..