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The control of broadband steady state vibration amplitude of a multi-mode system is presented. This objective is achieved using an Active Dynamic Vibration Absorber (ADVA). The stiffness property of the ADVA is adaptively tuned to attenuate the vibration of the multi-mode system at resonance. The ADVA detects the excitation frequency of the multi-mode system and calibrates its stiffness property to give the required stiffness for that mode. To implement the ADVA, a prototype model with low modal frequencies is designed. The equations of the steady state response of the multi-mode system with the attached ADVA are derived. The behavior of the prototype model when the ADVA is attached to different locations is used to determine the optimal location of the ADVA. The simulation result shows a reduction in the broadband of the multi-mode system. The result of the implementation of the ADVA reveals a 46% , 73% and 97% vibration amplitude reduction at first, second and third mode of the multi-mode system respectively.

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Civil structures experience vibrations due to natural dynamic forces such as earthquakes and wind loads. Often, mass-spring system is used to reduce such vibrations. The mass-spring system can either serve as absorbers or dampers. Usually, such system is tuned to absorb or damp a single frequency of excitation or resonance frequency respectively. However, ability to vary the absorber's natural frequency would allow broadband vibration absorption. In this paper, an Active Mass Damper (AMD) is presented to eliminate broadband vibration. The lowest frequencies are the main interest as they cause larger displacement. The AMD is tuned actively to match the first three resonance frequencies of a three story building model thus making it effective for a broadband vibration control. The tuning of AMD's natural frequency is done using piezoelectric patch that effectively change its stiffness. Simulation studies on the performances of the AMD are shown. The optimal location of the AMD is also identified. The findings of this study shows reduction in all response of the individual floors at the resonance frequencies.