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Structural Dynamics & Vibration Control Lab. 1 MR 유체 감쇠기를 이용한 사장교의 지진응답 제어 기법 정형조, 한국과학기술원 건설환경공학과 문영종, 한국과학기술원 건설환경공학과 고만기, 공주대학교 토목공학과 이인원, 한국과학기술원 건설환경공학과.

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Presentation on theme: "Structural Dynamics & Vibration Control Lab. 1 MR 유체 감쇠기를 이용한 사장교의 지진응답 제어 기법 정형조, 한국과학기술원 건설환경공학과 문영종, 한국과학기술원 건설환경공학과 고만기, 공주대학교 토목공학과 이인원, 한국과학기술원 건설환경공학과."— Presentation transcript:

1 Structural Dynamics & Vibration Control Lab. 1 MR 유체 감쇠기를 이용한 사장교의 지진응답 제어 기법 정형조, 한국과학기술원 건설환경공학과 문영종, 한국과학기술원 건설환경공학과 고만기, 공주대학교 토목공학과 이인원, 한국과학기술원 건설환경공학과 한국전산구조공학회 춘계 학술발표회 서울대학교, 서울 2002 년 4 월 13 일

2 Structural Dynamics & Vibration Control Lab. 2 OUTLINE Introduction Benchmark Problem Statement Seismic Control System Using MR Dampers Numerical Simulation Results Conclusions

3 Structural Dynamics & Vibration Control Lab. 3 INTRODUCTION The control of cable-stayed bridges is a unique and challenging problem. During the 2 nd International Workshop on Structural Control (Hong Kong, 1996), a working group was formed to develop a benchmark control problem for bridges. Dyke et al. have developed a benchmark control problem for seismically excited cable-stayed bridges (2000).

4 Structural Dynamics & Vibration Control Lab. 4 Semiactive Control Using MR Dampers –Magnetorheological (MR) fluid dampers: new class of semiactive control devices that utilize MR fluids to provide controllable damping forces.

5 Structural Dynamics & Vibration Control Lab. 5 Semiactive Control Using MR Dampers –Magnetorheological (MR) fluid dampers: new class of semiactive control devices that utilize MR fluids to provide controllable damping forces.

6 Structural Dynamics & Vibration Control Lab. 6 Semiactive Control Using MR Dampers –Magnetorheological (MR) fluid dampers: new class of semiactive control devices that utilize MR fluids to provide controllable damping forces.   MR damper-based control strategies Reliability of passive control devices Versatility and adaptability of fully active control system – –Attractive features Bounded-input, bounded-output stability Small energy requirements

7 Structural Dynamics & Vibration Control Lab. 7 Objective of This Study: to investigate the effectiveness of semiactive control strategies using MR fluid dampers for seismic protection of cable-stayed bridges

8 Structural Dynamics & Vibration Control Lab. 8 BENCHMARK PROBLEM STATEMENT   Missouri Side – –350 m main span – –142m side span – –128 Cables   Illinois Approach – –12 additional piers – –570 m 570 m636 m Benchmark Bridge Model –Under construction in Cape Griardeau, Missouri, USA. –To be completed in 2003.

9 Structural Dynamics & Vibration Control Lab. 9 Longitudinal excitation applied simultaneously. For proposed controllers, designers must define –Sensor models and locations –Device models and locations –Control algorithm Control Design Problem K(s)

10 Structural Dynamics & Vibration Control Lab. 10 El Centro PGA = 0.36g Historical Earthquakes Considered

11 Structural Dynamics & Vibration Control Lab. 11 El Centro PGA = 0.36g Mexico City PGA = 0.14g Historical Earthquakes Considered

12 Structural Dynamics & Vibration Control Lab. 12 El Centro PGA = 0.36g Mexico City PGA = 0.14g Gebze Turkey PGA = 0.26g Historical Earthquakes Considered

13 Structural Dynamics & Vibration Control Lab. 13 Peak Responses (J 1 – J 6 ) Peak Responses (J 1 – J 6 ) – Base shear – Shear at deck level – Overturning moment – Moment at deck level – Cable tension – Deck displacement at abutment Normed Responses (J 7 – J 11 ) Normed Responses (J 7 – J 11 ) –Base shear – Shear at deck level –Overturning moment – Moment at deck level –Cable tension Evaluation Criteria Control Strategy (J 12 – J 18 ) Control Strategy (J 12 – J 18 ) –Peak control force and device stroke –Peak and total power required –Number of control devices and sensors

14 Structural Dynamics & Vibration Control Lab. 14 SEISMIC CONTROL SYSTEM USING MR DAMPERS Sensors –Five accelerometers –Four displacement transducers –24 force transducers for measuring control forces Control Devices –24 MR dampers (capacity: 1000 kN/each)

15 Structural Dynamics & Vibration Control Lab. 15 Previous methods: based on the small-scale damper  Bingham model (Stanway et al. 1985, 1987)  Simple Bouc-Wen model (Spencer et al. 1997)  Modified Bouc-Wen model (Spencer et al. 1997) Proposed method: based on the large-scale damper  Modified Bouc-Wen model (Spencer et al. 1997) Dynamic Model of MR Dampers

16 Structural Dynamics & Vibration Control Lab. 16 Previous methods: based on the small-scale damper  Bingham model (Stanway et al. 1985, 1987)  Simple Bouc-Wen model (Spencer et al. 1997)  Modified Bouc-Wen model (Spencer et al. 1997) Proposed method: based on the large-scale damper  Modified Bouc-Wen model (Spencer et al. 1997) Dynamic Model of MR Dampers

17 Structural Dynamics & Vibration Control Lab. 17 where Control force: Control force: First-order filter: First-order filter:, and Modified Bouc-Wen Model (Spencer et al. 1997)

18 Structural Dynamics & Vibration Control Lab. 18 ParameterValueParameterValue aa 46.2 kN/mk0k0 0.002 kN/m bb 41.2 kN/m/Vk1k1 0.0097 kN/m c 0a 110 kNs/m  164 m -2 c 0b 114 kNs/m/V  164 m -2 c 1a 8359 kNs/mA1107.2 c 1b 7483 kNs/m/Vn2 x0x0 0.0 m  100 Optimized Parameters of Dynamic Model for MR Dampers

19 Structural Dynamics & Vibration Control Lab. 19 Physical Structure

20 Structural Dynamics & Vibration Control Lab. 20 Physical Structure Detailed F.E. Model ~ 10 5 - 10 6 DOF

21 Structural Dynamics & Vibration Control Lab. 21 Physical Structure Detailed F.E. Model ~ 10 5 - 10 6 DOF Evaluation Model ~ 10 2 - 10 3 DOF

22 Structural Dynamics & Vibration Control Lab. 22 Physical Structure Detailed F.E. Model ~ 10 5 - 10 6 DOF Evaluation Model ~ 10 2 - 10 3 DOF Control Design Model ~ 10 - 10 2 DOF

23 Structural Dynamics & Vibration Control Lab. 23 Control Design Model Reduced-Order Model (30 states) –By forming a balanced realization and condensing out the states with relatively small controllability and observability grammians

24 Structural Dynamics & Vibration Control Lab. 24 Control Law MR Damper Structure Decision Block Nominal Controller Control Strategy for Semiactive Control

25 Structural Dynamics & Vibration Control Lab. 25 Control Law MR Damper Structure Decision Block Nominal Controller Alternatively, H , Cumulant Control, Risk Sensitive, etc., can be employed. LQG / H 2 Linear Output Feedback Controller Control Strategy for Semiactive Control

26 Structural Dynamics & Vibration Control Lab. 26 Control Law MR Damper Structure Decision Block Nominal Controller Clipped-Optimal Control u = 0 u = u max Control Strategy for Semiactive Control

27 Structural Dynamics & Vibration Control Lab. 27 Weighting Parameters for Semiactive Control Appropriate Weighting Parameters by Stochastic Response Analyses –Overturning moment (Q over_mom ) –Deck displacement (Q deck_disp ) Performance Index where Q: Response weighing matrix R: Control force weighting matrix (identity matrix)

28 Structural Dynamics & Vibration Control Lab. 28 NUMERICAL SIMULATIONS Comparison Methods –Ideal active control –Ideal semiactive control –Passive control using MR dampers Passive-off (command signal u = 0 Volts) Passive-on (command signal u = 10 Volts) –Semiactive control using MR dampers Values of Optimized Weighting Parameters –Q over_mom = 6×10 -9 ; Q deck_disp = 6×10 3

29 Structural Dynamics & Vibration Control Lab. 29 Time-History Responses (Base Shear Force) El Centro earthquake: 71% reduction in peak Gebze Turkey earthquake: 64% reduction in peak kN kN Mexico City earthquake: 54% reduction in peak kN

30 Structural Dynamics & Vibration Control Lab. 30 Maximum Evaluation Criteria (Peak Responses)

31 Structural Dynamics & Vibration Control Lab. 31 Maximum Evaluation Criteria (Normed Responses)

32 Structural Dynamics & Vibration Control Lab. 32 Maximum Evaluation Criteria (Control Strategy)

33 Structural Dynamics & Vibration Control Lab. 33 Robustness to Earthquake Motion Intensities

34 Structural Dynamics & Vibration Control Lab. 34 CONCLUSIONS A semiactive control strategy using MR dampers has been proposed for the benchmark bridge problem. The performance of the proposed semiactive control design using MR dampers nearly achieves the same performance as that of the ideal active or semiactive control system. MR dampers show great promise for response control of seismically excited cable-stayed bridges.


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