Experimental shake table validation of damping behaviour in inerter-based dampers

Inerter-based-dampers have received substantial interest from the earthquake engineering community in the last two decades. These typically consist of an inerter, a linear spring and a viscous damper arranged into various possible configurations. In this paper, for the first time, experimental results are presented from shake table tests on a scaled three-storey structure with an inerter-based damper included, in order to suppress vibration amplitudes at the resonant frequencies. In particular two types of device are used to demonstrate the differences between using viscous and hysteretic damping in the inerter-based device. The two different types of experimental dampers were manufactured using eddy current dampers and gel damping material. The inerter was manufactured based on a flywheel design. The experimental results were compared with four analytical models tuned to suppress vibrations in the first resonance; namely the tuned-inerter-damper, the tuned-inerter-hysteretic-damper, the tuned-mass-damper-inerter, and the tuned-mass-hysteretic-damper-inerter. These experimental results confirm the observations made from the models that the suppression of higher resonance peaks is significantly different between the viscous and hysteretic damped inerter-based-dampers. Consequently, it is recommended that future studies exploring the performance of inerter-based seismic mitigation systems pay close attention to the damping mechanisms that are prevalent within the structure.