Optimal and seismic response analysis of inter-story isolation system with tuned inerter damper (IIS-TID)

The optimal and seismic performance of the inter-story isolation with tuned inerter damper (IIS-TID) is studied using simplified 3-degree-of-freedom (3DOF) and multi-degree-of-freedom (MDOF) models. Considering the spatial relationship between the inertial mass and the damper units, two distinct models—referred to as Model A and Model B—were established. Firstly, a 3DOF motion governing equation is used to derive the seismic response variance of the substructure, superstructure, and isolation layer of IIS-TID system under white noise excitation. The effects of structural and TID parameters on enhanced control are analyzed. Considering different objective functions, the frequency and damping parameters are optimized and the simplified expression of the optimal TID with each structure parameter is conducted. Further, comparison of the seismic response of the IIS with and without TID is made by using a MDOF model example under ordinary and near-fault earthquake excitation. Finally, the sensitivity of the optimized design parameters of the TID is analyzed as reference for engineering practice. The results illustrate the TID system is effective to control acceleration and story drift responses of the substructure, superstructure, and isolation layer of the IIS, especially for isolation displacement and substructure acceleration.