On the Seismic Protection of Existing Structures: A Large-Scale Modelling of Nonlinear Soil-Structure-TMD Interaction

Design of Tuned Mass Dampers (TMDs) is a very debated topic, with wide literature exploring different strategies for optimal tuning of such devices to mitigate earthquake-induced structural vibration. Notwithstanding, the interaction with the foundation soils can significantly alter the dynamic response of the structural system, reducing the effectiveness of the anti-seismic device, as demonstrated by far for conventional absorbers only. In this study, an advanced numerical investigation on the seismic performance of a coupled soil-structure-TMD system is presented, referring to a non-conventional, large mass ratio TMD (LM-TMD) applied to a real case study. The computation procedure was implemented in OpenSees, allowing for an accurate description of the nonlinear behaviour of both the structural members and the soil. The LM-TMD consists in a superelevation of the existing structure, connected to the latter through a combination of bearing devices providing the desired dynamic coupling between them. The use of the parallel computing on a supercomputer architecture was needed to handle the extremely high computational demand of the nonlinear time domain analyses. The results show that soil-structure interaction significantly alters the LM-TMD performance during strong motion with respect to the structural analysis with fixed base, because it modifies the dynamics of the entire structural system. However, the large mass of the anti-seismic device appears as a promising solution to limit the maximum structural deformations and improve the seismic performance.