Effectiveness of an innovative seismic resilient superelevation in an archetype, existing soil-structure system

Tuned Mass Dampers (TMDs) can be used for mitigating vibrations in structures caused by ground motion, with an effectiveness significantly increasing with the TMD mass. However, due to spatial constraints, the latter is usually limited to 2-3% of the structural mass. As a remedy, in a novel fashion the TMD can be regarded as a superelevation of the existing layout, potentially having a mass of 30-40% of the structural one. This approach, referred to as Large Mass ratio TMD (LM-TMD), can be particularly advantageous for retrofitting existing buildings. Conversely to earlier studies overlooking the soil compliance, this paper shows numerical evidence about the role of soil-structure interaction on the seismic effectiveness of LM-TMDs in an archetype building designed in accordance with old technical provisions. This is accomplished through the development of a coupled soil-building-LM-TMD model in OpenSees, simulating the nonlinear interactions between soil and structure under multi-directional seismic loading. The results of the nonlinear dynamic analyses shed light on the marked enhancement of the performance of the benchmark building produced by LM-TMDs compared to conventional dampers and, at the same time, the favourable or detrimental role of soil-structure interaction. The latter induces combined deformation modes of the structural system, further magnified by a pronounced nonlinear soil behaviour in case of severe scenarios, pointing out the necessity of a substantial LM-TMD mass for avoiding adverse effects on the superstructure response.