Semi-active control of pendulum-like TMD with variable length
Date Issued
2011
Date
2011
Author(s)
Lien, Kuan-Hua
Abstract
The tuned mass damper has been well developed and widely applied in vibration reduction for buildings today. However, it is very sensitive to frequency ratio and not adaptive under winds which are different from the design ones. For this reason, an active tuned mass damper was developed. Although active tuned mass damper possesses adaptive function, it must have control algorithms, sensors and external power. Stability may also be a problem. In recent years, the semi-active tuned mass damper is widely studied because it combines the stability of passive tuned mass damper with adaptability of active tuned mass damper. Its adaptive function is realized only by changing system parameters to reach the control effect indirectly.
In view of this, the semi-active control of pendulum-like tuned mass damper (SAPTMD) with variable pendulum length is investigated. In addition to the optimal design theory for the pendulum-like tuned mass damper (PTMD) with nonlinear viscous damper, the optimal, adaptive and combined stiffness control algorithms for SAPTMD are proposed and compared in this study. When the dissipated energy is insufficient for the demand of SAPTMD, the controllable restoring force is provided by variable pendulum length based on optimal stiffness control algorithm to dissipate energy. For the detuning effect, the adaptive stiffness control algorithms through two identified methods which are Hilbert transform-polynomial fitting and relation of maximum structural responses to track the instantaneous frequency of structure to keep the optimal frequency ratio by variable pendulum length. When the inadequate energy dissipation and the detuning effect occur simultaneously, it can be overcome through the combination of optimal and adaptive stiffness control control algorithms.
The multi-degree-of-freedom (MDOF) and single-degree-of-freedom (SDOF) structures implemented with the SAPTMD using three stiffness control algorithms under the white-noise wind, respectively, are taken as examples to conduct the numerical simulation and parameter analysis. Based on numerical results, no matter the structure is MDOF or SDOF, the functions of the SAPTMD using three stiffness control algorithms can be achieved, respectively. By the parameter analysis results, the effectiveness of the SAPTMD using optimal stiffness control algorithm is sensitive to the frequency ratio but not that sensitive to the damping coefficient; the SAPTMD using adaptive stiffness control algorithms or combined stiffness control algorithms are not sensitive to both frequency ratio and damping coefficient. The robustness of the SAPTMD using three stiffness control algorithms are better than that of the PTMD under sinusoidal wind force, respectively. Finally, the feasibility of the SAPTMD using the three stiffness control algorithms is illustrated numerically by using the Taipei 101 subjected to the design wind force. From the numerical verification, SAPTMD using the three stiffness control algorithms are so effective that the requirement of serviceability of the buildings can be met.
Subjects
pendulum-like tuned mass damper
optimal design theory
variable pendulum length
variable stiffness
semi-active control
optimal stiffness control
adaptive stiffness control
combined stiffness control
Type
thesis
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