Improved seismic base isolation combined with fluid inerter and tuned mass damper

The aim of this contribution is to present an improved seismic base isolation combined with fluid inerter and tuned mass damper (TMD). This combined system exploits the advantageous properties of the fluid inerter device for an optimized structural control of base-isolated buildings. In particular, this device is based on the inertia of a fluid passing through a helical tube surrounding a cylinder equipped with piston. Such inertia induces a beneficial mass-amplification effect that improves the performance of the attached TMD, resulting in the so-called tuned mass damper inerter (TMDI). Moreover, the fluid inerter has some inherent damping properties due to the pressure drops occurring in the helical channels induced by the fluid viscosity. The parameters of the fluid inerter are determined through a numerical procedure aimed to optimize the structural control of base-isolated structures and a sensitivity analysis is also performed. Finally, a practical procedure for converting the optimal parameters obtained from the optimization procedure into a realistic fluid inerter device is presented and applied to a simple case study.