A novel tuned torsional mass damper (TTMD) for seismic protection of structures

Energy dissipators are being increasingly utilized in the seismic protection of both newly constructed and retrofitted buildings. However, their control effectiveness would decline when applied to the stiff structures with small responses, such as drifts and inter-story velocities. To more effectively dissipate the vibration energy, this paper proposes a novel energy dissipator dubbed as tuned torsional mass damper (TTMD) based on the amplification effect of inerter. In particular, the conceptual design and ideal mechanical model of the proposed TTMD are firstly elaborated. A single degree of freedom (SDOF) system is then established to derive the optimal parameters of TTMD, namely the frequency and damping ratios, based on the fixed-point theory. Subsequently, a three-story benchmark building is adopted to demonstrate the control effectiveness of TTMD in the frequency domain. For comparison, the control effectiveness of the conventional viscous damper (VD) and viscous mass damper (VMD) are also examined. Moreover, parametric studies are conducted to investigate the influences of the mass ratio, secondary mass ratio, and lead of ball screw on the control performances of TTMD, and sensitivity analyses are also performed to assess the robustness of TTMD against the structural uncertainties. Finally, case studies are performed to further illustrate the control performance and the hysteretic behaviors of TTMD in the time domain. The results show that the proposed TTMD is more effective than the conventional VD and VMD in reducing the seismic responses of building; the relative angle of TTMD can be effectively reduced by increasing either the mass ratio or the lead of ball screw. The proposed TTMD could be a promising and viable alternative to conventional dampers in the field of structural vibration control.