Civil engineering structures are prone to collapse when subjected to severe seismic events, thus, protecting them from undesired vibrations is of vital importance. This paper proposes an innovative base isolation system based on a semi-active inerter using magnetorheological (MR) technology. Through the employment of an MR bearing, the inertance of the semi-active inerter could be switched between a large value and a small value, adapting to various seismic events. A scaled three-storey building based on the scaling laws was developed to evaluate the performance of the proposed novel base isolation system, and the isolation system consists of four rubber bearings and the semi-active inerter. Four scaled earthquake signals with different dominant frequencies were given as the ground motion excitations, a Short Time Fournier Transformation (STFT) methodology was utilized to recognize the dominant frequency of the input excitations, then output the desired working mode of the inerter. Finally, both the simulation and the experimental results indicated that the proposed base isolation system could provide superior vibration mitigation capacity.
 

MR bearing,inerter,base isolation