Impact of Soil-Structure Interaction on the Effectiveness of Tuned Mass Dampers

Tuned Mass Dampers (TMDs) can represent an attracting solution to mitigate vibrations of a structure under seismic excitation, but their effectiveness can be considerably altered by the dynamic interaction with the foundation soil. The available design criteria for TMDs do not account for these effects and can therefore lead to a non-optimised structural performance. In this paper an investigation onthedynamicinteractionoftheTMDwiththewholesoil-structuresystem is presented, with the objective of highlighting the system parameters governing the response and the effectiveness of the device as seismic protection. An interpretative model of the soil-structure-TMD system expressed in a rigorous nondimensional form is proposed, and an extensive global sensitivity analysis on its performanceunderharmonicloadingiscarriedout.Theidentificationofthetypical performanceregionsshowsthattheseismiceffectivenessofaTMDismainly controlledbyalimitednumberofparametersdescribingthestructuralbehaviour and the soil-structure interaction, such as the structure-to-soil relative stiffness and those governing foundation rocking. The non-dimensional system parameters leading to either a favourable or detrimental effect on the TMD performance due to soil-structure interaction are also identified, and two design methodologies proposed in the literature are critically assessed in light of the framework proposed.