Wave vibration mitigation of offshore structures using a compliant cell tuned liquid mass damper

Abstract

The water depth could be very small in a typical water tank used as a tuned liquid mass damper (TLMD) for functional reasons. This may result in a higher sloshing mass than the impulsive mass, leading to a thrashing phenomenon. The present study proposes an innovative geometry modification of a deep-water tank by compartmentalisation to minimise such phenomena for using it as a TLMD to mitigate wave-induced vibrations of offshore jacket platforms. Dividing the single tank into several cell tanks maintains the deep tank condition for a wide water level fluctuation. Thereby, such modification maximises the impulsive mass and utilises most of the water mass as the auxiliary mass of the TLMD, even for a low water depth. The efficacy of the proposed liquid mass damper in controlling the wave-induced vibration of a jacket platform is demonstrated by comparing its performance with a conventional TLMD. A probabilistic performance analysis is also made to show its effectiveness considering the stochastic nature of wave load. Further, a comparative study with traditional TLMD under seismic excitation demonstrates its efficacy in controlling the vibrations of building structures.