Combined Tuned Mass Dampers for structural vibration control

A Combined Tuned Mass Damper (CTMD), including a Tuned Liquid Column Damper (TLCD) integrated on the top of a traditional Tuned Mass Damper (TMD), is proposed to control vibrations of a Single Degree-Of-Freedom (SDOF) structure. This device can also be considered as a new hybrid type of tuned mass damper. The gained results from the parametric study indicate that the mass ratio between the TLCD and the TMD significantly affects the CTMD's effectiveness. In order to assess the structural vibration absorption capacity of this device, the effectiveness and robustness of an optimized CTMD are compared with those of optimum TMD and TLCD with the same weight as the CTMD. The numerical simulations show that the proposed CTMD provides a higher performance over a broader excitation frequency domain compared with both a conventional TMD and TLCD in mitigating structural vibration. Furthermore, the frequency response curve of the structure using the CTMD is relatively flat, whereas the frequency response curves of the structure with the TMD and TLCD remain a two-peak characteristic on the same frequency range considered. In another aspect, although the optimum CTMD is not more robust than the TMD or TLCD in resisting the change of the structural stiffness, it offers a wider range for choosing the frequency and damping ratio to aim at remaining similar efficiency to that of the optimized TMD (or TLCD). Therefore, a CTMD is much more robust than a single TMD or TLCD having equal weight to the CTMD. For parameters of the CTMD, the present research also indicates that the damping ratio of the TMD does not display an essential role in the CTMD. In contrast, although the TLCD mass is much smaller than the TMD mass, the appearance of the TLCD is very important in this device.