Effect of inerter for seismic mitigation comparing with base isolation

Summary In this paper, the effect of inerter arranged at the bottom of the structure on seismic mitigation is studied in comparison with base isolation system (BIS). First, a simplified two degree‐of‐freedoms (DOFs) structure is used to study the influence of the inerter on the modal characteristics and the transfer function of the structure by means of the analytical solutions. Second, regarding a multiple DOFs structure, an H2‐norm‐based parameter optimization algorithm is used to find the optimal inertance‐mass ratio, which is corresponding to the optimal structural damping performance. Finally, a numerical study is conducted to verify the feasibility of the optimization algorithm and the damping effect under the optimal parameters by simulations with artificial seismic waves. Related results have shown that with the increase of inertance, the addition of inerter in substructure is also effective in reducing the basic natural frequency and changing the first‐order mode as BIS does. The H2‐norm evaluation of the simplified model shows the existence of the optimal inertance‐mass ratio, which is finally verified by the optimization results on the multiple DOFs structure. Results have indicated the superiority of the inerter‐based systems compared with the BIS in terms of the less dependence on site conditions, the better controlled displacement of the substructure and superstructure, and the less seismic energy input to the structure.