An enhanced base isolation system equipped with optimal tuned mass damper inerter (TMDI)

Abstract

Summary In seismic base isolation, most of the earthquake‐induced displacement demand is concentrated at the isolation level, thereby the base‐isolation system undergoes large displacements. In an attempt to reduce such displacement demand, this paper proposes an enhanced base‐isolation system incorporating the inerter, a 2‐terminal flywheel device whose generated force is proportional to the relative acceleration between its terminals. The inerter acts as an additional, apparent mass that can be even 200 times higher than its physical mass. When the inerter is installed in series with spring and damper elements, a lower‐mass and more effective alternative to the traditional tuned mass damper (TMD) is obtained, ie, the TMD inerter (TMDI), wherein the device inertance plays the role of the TMD mass. By attaching a TMDI to the isolation floor, it is demonstrated that the displacement demand of base‐isolated structures can be significantly reduced. Due to the stochastic nature of earthquake ground motions, optimal parameters of the TMDI are found based on a probabilistic framework. Different optimization procedures are scrutinized. The effectiveness of the optimal TMDI parameters is assessed via time history analyses of base‐isolated multistory buildings under several earthquake excitations; a sensitivity analysis is also performed. The enhanced base‐isolation system equipped with optimal TMDI attains an excellent level of vibration reduction as compared to the conventional base‐isolation scheme, in terms not only of displacement demand of the base‐isolation system but also of response of the isolated superstructure (eg, base shear and interstory drifts); moreover, the proposed vibration control strategy does not imply excessive stroke of the TMDI.

Analytical solution of seismic response of base‐isolated structure with supplemental inerter

“…Inerter is a two-terminal device with the property that the force applied at its two terminals is proportional to the relative acceleration between them, 2 with the constant proportionality named as the inertance in the unit of mass (eg, kilogram). [10][11][12][13][14] Pradono et al 10 investigated the effectiveness of application of inerter to BIS. [3][4][5] Inspired by the successful application of inerters in mechanical engineering, the structural engineering community is now engaged in applying inerters to vibration control of buildings subjected to seismic excitations.…”

Seismic response control of base‐isolated buildings using multiple tuned mass dampers

“…However, Hessabi et al concluded that the effectiveness of the TMDs in base‐isolated structures with nonlinear base isolation systems is not as significant as for the linear base isolation systems. De Domenico and Ricciardi and De Domenico et al were mainly focused on the possibility of enhancing the effectiveness of the TMD by adding additional rotational inertia via the inerter configuration for response control of isolated buildings.…”

Earthquake Protection of Existing Structures with Limited Seismic Joint: Base Isolation with Supplemental Damping versus Rotational Inertia

“…It has been found that by attaching a TMD to the BIS, a certain reduction of the displacement demand of a base-isolated structure is achieved, depending on the TMD mass. Conversely, applications of inerter-based devices in the context of base-isolated structures are really few [21][22][23][24][25]. To the authors' best knowledge, the dynamic layout of the BIS coupled with the TMDI has never been studied in the literature as a seismic retro tting strategy of existing structures, which constitutes the main novelty of the present research work.…”