Controlling Floor Vibration with Active and Passive Devices

Abstract

This paper reviews research, conducted by the authors over the last decade, pertaining to the control of ex- cessive floor vibration using active and passive devices. The active device studied uses a proof-mass actuator to deliver the control force to the floor system. Effectiveness and stabil- ity characteristics for a single-input/single-output (SISO) con- trol scheme, using velocity feedback, are explored. The SISO system is shown to increase damping to 40% of critical on an experimental floor when amplitudes remain in the linear range. When implemented on two in-place floors, at least a 70% reduction in vibration amplitudes due to walking was ob- served. Next, the benefits of expanding to a practical single- input/multi-output (SIMO) control system are identified. Ad- ditionally, techniques to optimize the SIMO scheme are presented. Because of the stability characteristics of the controlled system, the improvement noted for the SIMO scheme is most dramatic for floors with fundamental frequen- cies near the natural frequency of the actuator. I na2H zfloor example, a SIMO control scheme provided seven times more reduction than that of the SISO system. The passive device research focuses on the experimental implementation of tuned mass dampers (TMDs) to control floor vibration. Two different configurations are explored. The uniqueness of the first device is that liquid filled bladders are used to provide an economical damping mechanism. When implemented on an office floor, a significant improvement of walking vibration lev- els was observed. Satisfaction with the repair was noted from the occupants. The second device utilizes a configuration that has great flexibility in the field, thus allowing for more eco- nomical mass production. Using two TMDs, a significant re- duction of response was noted for the 5 and 6 Hz modes. Research to improve these active and passive strategies continues and will be reported as significant results are achieved.