Abstract:In order to solve the problem of mistuing of tuned mass damper (TMD) and overcome the difficulty to adjust the frequency of TMD during normal using, a selfadjusting TMD was proposed. The selfadjustable TMD was generated by a tank instead of solid mass, using a servo control system to start the drive to change the mass of (TMD) and spontaneously adjust the frequency of TMD to main structure near the natural frequency of vibration, under the special harmonic excitation. The vibration reduction effects with or without this selfadjustable device under freedom vibration and forced vibration were set to investigate the effect on improving the previous TMD based on the equivalent damping ratio, the peak value of acceleration, and rootmeansquare. The results indicate that the selfadjustable TMD has a good convergence and could increase the equivalent damping ratio of the structure. The selfadjustable TMD has good vibration tuned effects for the various excitation conditions.