케이블 진동 감쇠를 위한 반능동 제어 장치 성능의 실험적 평가

1. 2004년도 한국전산구조공학회 추계 학술발표회 목포해양대학교 2004년 10월 9일 케이블 진동 감쇠를 위한 반능동 제어 장치 성능의 실험적 평가 장지은, 한국과학기술원 건설 및 환경공학과 석사과정 정형조, 세종대학교 토목환경공학과 조교수 정 운, 현대건설기술개발원 주임연구원 이인원, 한국과학기술원 건설 및 환경공학과 교수

2. Contents • Introduction • Cable Damping Experimental Setup • Experimental Results • Conclusions Structural Dynamics & Vibration Control Lab., KAIST, Korea

3. Introduction • Cable • Cables are efficient structural elements that are used in • cable-stayed bridges, suspension bridges and other cable • structures. • Steel cables are flexible and have low inherent damping, • resulting in high susceptibility to vibration. • Vibration can result in premature cable or connection • failure and/or breakdown of the cable corrosion protection • systems, reducing the life of the cable structure. • Numerous passive and active cable damping studies have • been performed and full-scale applications realized. Structural Dynamics & Vibration Control Lab., KAIST, Korea

4. Semiactive damping system - Johnson et al. (1999, 2000): verification of the efficacy of a semiactive damper for a taut/sagged cable model - Christenson (2001): experimental verification of the performance of an MR damper in mitigating cable responses by using a medium-scale cable - Ni et al. (2002), Ko et al. (2002), Duan et al. (2002): field comparative tests of cable vibration control using MR dampers (the world’s first time implementation of MR-based smart damping technology in civil engineering structures) Structural Dynamics & Vibration Control Lab., KAIST, Korea

5. Objectives • To experimentally verify the performance of the MR • damper-based control systems for suppressing vibration of • real-scaled stay cables using various semiactive control • algorithms Structural Dynamics & Vibration Control Lab., KAIST, Korea

6. Cable Damping Experimental Setup • Schematic of smart cable damping experiment spectrum analyzer shaker flat-sag cable digital controller MR dampers : shaker force Where, : damper force : displacement at damper location : evaluation displacement : control signal Structural Dynamics & Vibration Control Lab., KAIST, Korea

7. Cable Real-scaled cable at HICT Structural Dynamics & Vibration Control Lab., KAIST, Korea

8. Cable model • Transverse motion of cable could be modeled by • the motion of a taut string because of small sag • (0.1% sag-to-span ratio with tension of 500 kN). Structural Dynamics & Vibration Control Lab., KAIST, Korea

9. where : transverse deflection of the cable : transverse damper force at location : transverse shaker force at location : angle of inclination Structural Dynamics & Vibration Control Lab., KAIST, Korea

10. MR damper • MR controllable friction damper • (RD-1097-01 from Lord Corporation) • Maximum force level: 100 N • Maximum voltage: 1.4 V Structural Dynamics & Vibration Control Lab., KAIST, Korea

11. MR damper installation • Twin damper setup • Location : 1.34m • from bottom support • Measurement : Damper force, • displacement, and • acceleration Structural Dynamics & Vibration Control Lab., KAIST, Korea

12. Cable exciting system (Kim et al. 2002) (1) Structural Dynamics & Vibration Control Lab., KAIST, Korea

13. Controller • The controller is constructed by the Matlab Real-Time • Workshop executed in real time using MS Visual C++. • The measured responses are acquired from displacement • and acceleration sensors at damper location and converted • into digital data by NI DAQ Card-6062E. Structural Dynamics & Vibration Control Lab., KAIST, Korea

14. Control algorithms: to calculate the command voltage input • Passive-mode cases • - passive-off (v=0V), • - passive-on (v= 1.4V) • - other passive-modes (v= 0.6V, 1.0V, 1.1V, 1.2V, 1.3V) Structural Dynamics & Vibration Control Lab., KAIST, Korea

15. Semiactive control cases (Jansen and Dyke 2000) • - Clipped-optimal control algorithm • where, Vmax=1.4V, Fd ci= the desired control force, and • Fd = the measured control force • - Control based on Lyapunov stability theory • where, z = the state vector, and • P = the matrix to be found using the Lyapunov • equation (2) (3) Structural Dynamics & Vibration Control Lab., KAIST, Korea

16. - Maximum energy dissipation algorithm where, vd = the velocity at the damper location - Modulated homogeneous friction algorithm (4) (5) P[i(t)] = i(t-s), where s = {min x0: i(t-x)=0} Structural Dynamics & Vibration Control Lab., KAIST, Korea

17. Experimental Results • Displacement in free vibration Displacement (m) Time (sec) Structural Dynamics & Vibration Control Lab., KAIST, Korea

18. Damping ratios for verification of performances • The amplitude-dependent damping ratios are calculated by • the Hilbert transform-based identification method • (Duan et al. 2002) Structural Dynamics & Vibration Control Lab., KAIST, Korea

19. Damping ratios in the passive-mode cases Damping ratio (%) Amplitude (mm) at the location of 10.2 m away from the bottom support Structural Dynamics & Vibration Control Lab., KAIST, Korea

20. Damping ratios in the semiactive control cases Damping ratio (%) Amplitude (mm) at the location of 10.2 m away from the bottom support Structural Dynamics & Vibration Control Lab., KAIST, Korea

21. Conclusions • The performance of MR damper-based control systems for suppressing vibration of stay cables is experimentally verified. • Semiactive control systems significantly improve the mitigation of stay cable vibration over the uncontrolled and the passive-off cases. • The control based on Lyapunov stability and the clipped- optimal control show slightly better performance than the passive-on case. • The Modulated homogeneous friction algorithm shows nearly the same performance as the passive-on case. Structural Dynamics & Vibration Control Lab., KAIST, Korea