Invited Workshop on Strong-Motion Record Processing Convened by

1. Invited Workshop on Strong-Motion Record Processing Convened by The Consortium of Organizations for Strong-Motion Observation Systems (COSMOS) Strong Motion Data Processing in Taiwan and its Engineering Application Chin-Hsiung Loh Department of Civil Engineering National Taiwan University Pacific Earthquake Engineering Research Center Richmond, California May 26, 27, 2004

3. Taiwan Strong Motion Instrumentation Program (TSMIP) 700 free-field stations 60 sets of strong motion arrays in structures 200-250 samples/sec 16/24-bits resolution Taiwan Rapid Earthquake Information Release System (TREIRS) 80 rapid stations 50 samples/sec 16-bits resolution An integrated seismic early warning system Strong Motion Instrumentation in Taiwan

4. No. of Earthquake 1989 1991 1994 1999 2003 Time (year) Chi-Chi earthquake

6. Using TREIRS to determine the earthquake intensity

7. CWB Earthquake Information Backup System 3rd Backup Line 3rd Backup line IDU CWB Third Backup Line Second Backup System First Backup Line Main Line First Backup Line Third Backup Line T1 專 線 Cisco7206 陽明山 HUB ATM/FR ISDN/PSTN Second Backup System HPP& Router Main Line 2nd Backup Line 3rd Backup line IDU Cisco 3640 1st Backup line CWB Meteorology Station HUB (集線器) Satellite Telephone Fax Tel Line Computer

8. Site Investigation at Each Strong Motion Station

10. Low-pass filter Input H(f) Least square straight line fit a0and a1 f f1 f2 Least square fit for v & a Correct accelerogram Integrate for v(t) High pass Least square fit for v01 and a2 Integrate for v2(t) Low-pass filter to get v4(t) f Differentiate V4(t) to get a10 Flow Chart for the Baseline Correction of Accelerogram (1)

11. Correct Accelerogram a6(t) Least square fit Integrate a6(t) for v4(t) Correct displacement Low-pass filter Low-pass filter to get d2(t) Correct velocity to get v6(t) Integrate for displacement d1(t) Calculate Velocity & Displacement from Corrected Accelerogram

12. Estimate Noise Level From Pre-event Record Input Acceleration a’(t) a1(t) = a’(t) - (noise level) Fourier transform F {a1(t)} Trend removal (using least square method) Error correction on measurement system: Low-pass filter: < 25 Hz 100% High-pass filter: >0.2 Hz 100% A1() Inverse Fourier Transform Output: a(t) =F-1 {A1()} Inverse Fourier Transform Output: v(t) = F -1 {V1()} Inverse Fourier Transform Output: d(t) = F -1 {D1()} V1()=A1() ∙(1/i ) D1()=V1() ∙(1/i ) Flow Chart for the Baseline Correction of Accelerogram & Generation of Velocity and Displacement (2)

13. Empirical mode decomposition 1 Extreme Sifting 2 Curvature Sifting 3 Intermittency Hilbert transform: Hilbert spectrum: (Time_frequency energy) Application damping estimation Loss damping factor Q(f) ( Q(f)=2 * damping ratio ) Empirical Mode Decomposition & Hilbert Transform (EMD+HHT)

15. Example: Using Chi-Chi Earthquake data recorded at Station TCU052 (Near-fault Ground Motion Data) Applied trend removal on velocity data Direct Integration

16. Example: Using Chi-Chi Earthquake data recorded at Station TCU068 (Near-fault Ground Motion Data) Applied trend removal on velocity data Direct Integration

17. Example:Using Chi-Chi Earthquake data recorded at Station CHY088 (Far-field Ground Motion Data) Direct Integration Applied trend removal on velocity data

18. Engineering Application of Taiwan Strong Ground Motion Data

19. PGA Attenuation Model

20. Site amplification: Predicted vs. Observed

21. Site Amplification Factor ▪ Using RTD & TSMIP data ▪ Depend on Intensity Level

22. Taiwan Rapid Earthquake Information Release System (TREIRS) Site Effect Modification Earthquake Parameters (Magnitude, Depth, Epicenter etc.) Attenuation Model Update estimation using Taiwan Rapid Information Release System Spatial Distribution of Ground Motion Estimation HAZ-Taiwan : Potential Earthquake Ground Motion Analysis

23. Generate Shake Map Observation Sa(1.0 sec) & Sa(0.3 sec) Estimation Sa(1.0sec & Sa(0.3 sec)

24. Taipei City Taipei Basin

25. 地 震 參 數 Microzonation Study of Taipei basin

27. ■︰ 0.8g ■︰ 0.7g ■︰ 0.6g ■ ︰ 0.5g ■︰ 0.45g ■︰ 0.40g ■︰ 0.35g ■ ︰ 0.30g S1D(T=1.0 s): 475 Yrs SSD(T=0.3 s): 475 Yrs SSM (T=0.3 s) : 2500 Yrs S1M (T=1.0 s) : 2500 Yrs ■︰ 1.0g ■︰ 0.9g ■︰ 0.8g ■ ︰ 0.7g ■︰ 0.55g ■︰ 0.50g ■︰ 0.45g ■ ︰ 0.40g • Map of Acceleration Response Spectrum

28. t-distribution(=3) Given earthquake Magnitude & Epicenter Distance  jtgr  jtgr J() t jgr() Modeling of phase spectra • Wavelet analysis • Concept of group delay time • Stochastic characteristics of group delay time • Mean value & Standard deviation of Group Delay time tjgr()=J()/

29. CWB Structural Seismic Monitoring Array

31. 400 350 300 250 200 150 100 50 0 2 4 6 8 10 12 14 Output Measurement: Bridge response data(EMD+HHT method) Longitudinal Direction Transverse Direction Mode 1: f = 1.083 Hz

32. Conclusions • The Taiwan Strong Motion Array (TSMIP-CWB) provides valuable ground • motion data for both seismology and engineering application. • These high resolution seismographs can record ground motion accurately up • to frequency of 50Hz. In engineering application there is no correction on the • original data except the constant DC trend removal. • Engineering applications of these Strong Motion Array Data include: • a. Generate ground motion attenuation model • b. Generate shake map for use in seismic emergency response, • c. Generate site amplification factor, • d. Develop Sa-value for short period and long period for Taiwan Seismic • Design Code, • e. Damage assessment program is now under developing and will be used • in building/bridge seismic monitoring array,

33. The End Thank you for your attention

34. Taiwan-Luzon Velocity field 80 mm/yr convergence across the active Taiwan arc-continent collision zone

38. Basin Effect : Site Amplification Taipei Basin

39. 北二高碧潭橋橋體-2 Z-Direction

41. Empirical Mode Decomposition