Verification of Hybrid Simulation

1. Verification of Hybrid Simulation by Ali. Ozdagli, Wang Xi, GeOu, Bo Li, GuoshanXu Shirley Dyke, Jian Zhang and Bin Wu Project funded by National Science Foundation - CMMI Grant #1011534 National Science Foundation of China – Project #90715036

2. Presentation Outline • Introduction • Background and Motivation • Experimental Setup • Modeling of the System • RTHS Comparison • HS Efforts • Conclusion

3. Introduction Need for Testing • Global performance of new systems • Nonlinear response Options • Shake-table: Scaled Structural Testing • Hybrid Simulation (HS)

4. Background “Comparison of Real-Time Hybrid Testing with Shake Table Tests for an MR Damper Controlled Structure” by Lin et al. (2009) • “The results show a close correlation between the shake table tests and the real-time hybrid simulation.” • “There is clearly a difference between the hybrid tests and shake table tests.”

5. Background “Development of a Versatile Hybrid Testing System for Seismic Experimentation” by Shao et al. (2012)

6. Motivation • How do we know? • RTHS and Numerical Simulations represent the real structural behavior? • Gain acceptance in community • Compare the RTHS to the real structure responses Numerical Simulation ? RTHS Shake Table

7. Challenges • Accurate modeling of the target structure • System Identification • Semi-active controllable nonlinear damper • Hard to model rate dependent dynamics • Damper-structure interaction

8. Objective • Verification of RTHS methodology using shake table tests on mid-scale structure Research Program • Phase 1: Numerical Modeling and Simulation • Phase 2: Shake Table Tests • Phase 3: RTHS Testing

9. Phase 1: Numerical Simulation Test Structure • Base Dimension: 1.84 m by 2.04 m • Story height: 1.2 m • Material: Structural Steel

10. MCK Update Method More details were given in ‘Modeling of Distributed Real-time Hybrid Simulation’ accessible from http://nees.org/resources/6641/ Model is awarded by NEES as the best simulation model.

11. MR damper numerical model • Lord MR damper RD-1005-03

12. Phase 2: Shake Table Tests Location: Harbin Institute of Technology Size: 3m×4m (shaking direction) Peak acceleration: ±1.33g Peak velocity: ±600 mm/s Stroke: ±125 mm Maximum payload: 12t Force capacity: 200kN Maximum overturning moment: 30 t-m Frequency bandwidth: 0 - 30 Hz Conducted uncontrolled, passive off, passive on and semi-active control cases

13. Comparison – Shake Table vs Simulation

14. Phase 3: RTHS MTS loading Frame @ HIT MTS Loading Frame, 2500kN, Internal LVDT Load cell, 15kN Lord MR damper, 2kN MTS Flex GT Controller Inner Loop Control Clamp for vertical loading

15. RTHS Setup Force Numerical substruc. Physical substruc. Complete Structure Damper Desired Displacement

16. RTHS Result: Kobe Due to the limitation of Pump Velocity Limitation, Piston maximum moving speed 50mm/s

17. RTHS Result: Morgan

18. Phase 3: RTHS (Replace pics with IISL Actuator) Shore Western loading Frame @ IISL 2 kip Actuator Loading Frame • High performance programmable DSP system plus high precision servo-hydraulic motion control system. Servo Valve Lord MR Damper

19. Compensation Performance NRMS: 3.62%

20. Comparison – ST vsRTHS

21. Remarks on RTHS • To verify the RTHS methodology, shake table responses at HIT are compared to RTHS results at IISL. • A new control oriented model updating method is implemented using mode shapes to derive MCK. • MCK model based on fully identified results • Accurate zero tracking • A new compensation scheme, RIAC is implemented. • High performance even in large noise/signal ratio condition • Flexible to choose loop shaping function • Experimental tuning is easy to perform

22. Model updating with UKF Numerical BRB Constrained Kalman filter Physical BRB

23. Physical BRB Numerical BRB

24. Physical BRB Numerical BRB Real-time hybrid test validations

25. Initial CUKF UKF

26. Finite element based sectional constitutive model • Section Yield Function • Section Restoring Force Model (RFM) When , Section- elastic When , Section- plastic where

27. Numerical example • Identification results • Model updating results

28. Experiment plan • Test scheme • Test setup and three cases of HS Traditional HS (Linear/Nonlinear) FE Model updating by HS Distributed Hybrid Simulation

29. Delay over-prediction Delay compensation based on over-prediction ①Calculate di+1 ②Predict with c ③Load with prediction ④Find force measure-ment Delay Compensation: Compensated Delay > System Delay

30. Fixed Number of Iterations with Interpolation (Shing et al) Implicit algorithms for RTHS Limitations: Iteration Intensive computation Time delay Equivalent Force Control Method (Wu et al)

31. New implicit algorithm based on over-prediction Process 1 Process 2 1、Modified Newton’s Method applied results in good iteration performance. 2、System delay is compensated for based on over-prediction method.

32. Test validation • Single time step • 10 seconds • Delay comptn error

33. Trans-pacific test between UCB and HIT

34. HIT,CHINA UCB, USA Data available @ http://peer.berkeley.edu/~aschell/DHS%20with%20HIT/

35. Acknowledgements • National Science Foundation - CMMI Grant #1011534 • National Science Foundation of China – Project #90715036 • HIT Lab • Steve Mahin & Andreas Schellenberg@ UCB • Tao Wang @ IEM Project data will be available @ NEES.org #1076

36. China-US collaborative project on hybrid simulation Bin Wu, Professor Harbin Institute of Technology YurongGuo, Professor Hunan University Tao Wang , Assoc Professor Institute of Eng. Mechanics Shirley Dyke, Professor Purdue University Jian Zhang , Associate Professor UCLA

37. THANK YOU!