Using tuned liquid column dampers (TLCDs) for heave motion mitigation of very large floating structures (VLFSs)

Abstract

In offshore engineering, tuned liquid column dampers (TLCDs) have been widely employed to mitigate the horizontal and pitch motions of floating structures. However, their application in controlling heave motion remains unexplored, due to the working mechanism of TLCDs. This study delves into the feasibility of deploying non-submerged TLCDs in very large floating structures (VLFSs) to achieve heave motion mitigation. Analytical models of a VLFS-TLCD system are developed in both the frequency and time domains. Five wave loading scenarios are considered for a VLFS with a size of 300 m × 100 m. An optimization design program using the genetic algorithm is developed to obtain the optimized control parameters of TLCDs. Based on the heave motion response amplitude operators, response spectra, and transmissibility curves of the VLFS-TLCD system, parametric analyses are undertaken for TLCDs to elucidate the influences of various key parameters on the control performance. Besides, the results of using conventional submerged fixed heave plates (FHPs) are also included for comparison. The outcome illuminates the effectiveness and control characteristics of non-submerged TLCDs in mitigating the heave motion of VLFSs in both the frequency and time domains.