Experimental and numerical study of a novel low-frequency tuned mass damper-inerter

A novel low-frequency tuned mass damper-inerter (LF-TMDI) with a rotor is proposed to significantly reduce the initial length and static stretching of the spring. The required installation space is thus reduced, allowing it to accommodate low-frequency vibration control. The proposed LF-TMDI can be installed inside a steel box girder (with internal installation space of 3 similar to 4 m), effectively controlling low-frequency vibrations (e.g., 0.2 Hz) for long-span bridges. A physical LF-TMDI device is fabricated, and the experimental results indicate that the damping of the device can be characterized by Coulomb damping or equivalent viscous damping. The equations of motion for the coupled system of the LF-TMDI device and the controlled structure are derived. Vibration tests confirm that the fabricated LF-TMDI device can effectively control the vibration of a low-frequency (0.5 Hz) oscillator. Numerical parametric analyses show that the TMDI control efficiency remains stable within a deviation range of ( + 5 parts per thousand) optimal damping ratio and ( + 1 %) optimal frequency ratio. In practical engineering, increasing the mass ratio between the LF-TMDI mass block and the main structure, and selecting an appropriate mass ratio between the equivalent mass provided by the rotor and the TMDI mass block, are effective ways to improve the performance of the LF-TMDI. Finally, the optimal stiffness and damping parameters of the LF-TMDI for free vibration control under common conditions are provided through similar parametric analysis.