Passive Vibration Control of Offshore Platforms Using Upgraded Tuned Liquid Column Damper With a Grounded Inerter

Abstract An upgraded tuned liquid column damper (UTLCD), combining a tuned liquid column damper (TLCD) with an undamped tuned mass damper (TMD), has recently been introduced and shown to be more efficient than a traditional TMD or TLCD. This study introduces an upgraded version of the UTLCD, where a UTLCD is connected to the ground through an inerter (UTLCDI), to passively control the vibration of offshore platforms. Unlike the earlier inerter-based TLCD models, the UTLCDI is simpler because it connects to the main structure with a spring. In this work, an analytical model of the UTLCDI–platform system is developed, in which a key improvement is that the mass ratio between the undamped TMD and TLCD is treated as a design variable rather than being fixed as done in previous works. This change offers more options in finding the optimal UTLCDI configuration. Then, optimal configurations of UTLCDI for different inertance ratios are determined. The obtained results show that an optimized UTLCDI is more effective and robust than an optimal UTLCD with the same weight. Specifically, the optimal configuration of UTLCDI, characterized by a higher inertance ratio, offers greater control effectiveness. Moreover, the maximum displacements of both the TMD mass and the liquid column in an optimized UTLCDI configuration are much smaller than those observed in the UTLCD. Additionally, with the same inertance ratio given, the UTLCDI provides better control performance compared to the inerter-based TMD (TMDI). However, it is less robust than the TMDI when the natural frequency of the structure changes.