WIND VIBRATION CONTROL USING A VARIABLE LENGTH PENDULUM MASS DAMPER

摘要

A Semi-active Variable-length Pendulum Mass Damper is modelled and applied to a single-storey building for proof of concept. Structural mass and stiffness are chosen to achieve resonance at the dominant frequency of wind excitation. A semi-active control law is formulated based on the horizontal component of the force generated by the pendulum. The control law yields the required change in length of the pendulum, i.e., the control input, and relies on measurement of only the storey displacement and pendulum angle for feedback. Various types of feedback, i.e., Constant-rate, Displacement, Displacement-Velocity, Displacement-Acceleration, and Acceleration feedback are considered in order to obtain the control input. The respective percentage attenuation in RMS (peak) displacement vis-a-vis the passive pendulum mass damper is 53 (47), 55 (48), 63 (54), 57 (46), 52 (36), and corresponding maximum percentage change in length of the pendulum is 12, 25, 9, -3, and 39. Thus, Constant-rate feedback provides effective control, although Displacement-Acceleration feedback control requires the least variation in pendulum length. Subsequently, the dynamics of a DC servomotor actuator is included in the control loop. After tuning the required gains, the performance obtained by including actuator dynamics is found to be nearly as good as that of the ideal-actuator system.