Enhancing the seismic performance of dual-isolated structure with optimal supplemental inerters

Abstract

Recently, the dual isolation system has been verified to be effective in decreasing the floor acceleration of superstructure and base overturning moments compared with the traditional base isolation system. However, a significant drawback of the dual isolation system is the amplification of the relative displacement of the superstructure. This study proposes an enhanced dual isolation configuration combined with supplemental inerters. By simplifying the dual-isolated structure with supplemental inerters as three degrees-of-freedom (3DOF) model, parametric studies on the modal characteristics of the simplified model have revealed that the transitions of the dual-isolated structure with supplemental inerters to base-isolated structure or fixed-base structure would emerge. Within a probabilistic framework, the optimal inertance values of supplemental inerters have been determined numerically by solving the constrained optimization problem accounting for displacement and acceleration variances of the structural responses. Finally, compared with the original dual-isolated structure and corresponding base-isolated structure, the advantages of the dual-isolated structure with optimal supplemental inerters over the original dual-isolated structure and the corresponding base-isolated structure have been demonstrated by time-history analysis. Consequently, the drawback of the dual-isolated structure has been addressed because the relative displacements of superstructure of the proposed dual-isolated structure with optimal supplemental inerters are considerably decreased compared with those of the original dual-isolated structure and to some extent reduced as well compared with those of the corresponding base-isolated structure.