Enhanced seismic isolation system by using a yoke-type inerter

Abstract. Previous studies have shown that inserting an inerter whose force-acceleration relationship is linear into the isolation layer of a base-isolated structure can effectively improve its seismic performance. A nonlinear strategy has the potential to provide a better control effect than its linear counterpart. This study proposed a yoke-type nonlinear inerter device by employing the Scotch yoke mechanism. The mechanical model of the proposed nonlinear inerter is built to illustrate the nonlinear inertial behavior using the Euler-Lagrange method. Then, The yoke-type inerter is incorporated into the isolation layer of a base-isolated structure to improve seismic performance. The relative displacement of isolation layer and responses of the superstructures are checked under different seismic events. The nonlinear inertial behavior of the yoke-type inerter is indicated by the proposed mechanical model. The relative displacement of the isolation layer and responses of the superstructures for the base-isolated structure with yoke-type inerter is smaller than that of the base-isolated structure with a linear inerter whose inertance is the same as the linearized yoke-type inerter, especially for the rare earthquake. It is said that the proposed yoke-type inerter can be seen as a candidate of the nonlinear inerter and can be used to improve the seismic performances of base-isolated structures.