Monitoring-based performance analysis of tuned mass dampers in tower structures. Slender structures, such as towers and masts, frequently exhibit unfavourable responses when subjected to dynamic loads, characterized by the non-negligible contribution of higher modes of vibration as well as resonant phenomena between the loads and the structure. To mitigate such responses, tuned mass dampers (TMDs) have been employed in several slender structures. A TMD is a structural sub-system fixed to a structure and “tuned” to counteract a response frequency, which is anticipated to induce large oscillations to the structure, through its out-of-phase response. The design of tuned mass dampers is based on modelling assumptions and on sparse observations of the dynamic behaviour of structures, which changes due to structural ageing, thus rendering the regular performance assessment of TMDs is essential. In this paper, a methodology for assessing TMD performance using structural health monitoring (SHM) data is presented. Specifically, the TMD functionality is assessed upon obtaining the phase shift between the TMD response and the response of the structure, which, according to TMD theory, indicates favourable dampening effect when assuming values close to 90°. The proposed methodology is validated via a case study of a telecommunication tower equipped with a TMD and an SHM system, showcasing the ability of the methodology to assess TMD performance.
