Passive Control of Heave Motion in an Offshore BLSRP for Enhanced Operational Safety
Abstract
: The buoyant leg storage and regasification platform (BLSRP) is a compliant offshore structure for liquefied natural gas (LNG) storage and regasification in deep waters. Although the hinged deck – leg arrangement improves structural performance, severe environmental loading may induce excessive radial leg motion and associated deck heave, affecting operational safety. To address this issue, a passive linear spring – based response control mechanism (LS-RCM) is proposed to limit the inward – outward radial motion of the buoyant legs, thereby indirectly suppressing excessive deck heave without altering the inherent compliant characteristics of the platform. Time-domain simulations incorporating irregular waves, current, and wind were performed in ANSYS AQWA for moderate, high, and very high sea states. Power spectral density analyses showed consistent suppression of heave response peaks with negligible shifts in dominant response frequencies. Phase-plot trajectories became more compact, indicating improved recentering behavior and enhanced dynamic stability. The LS-RCM also reduced response variability, with the deck-heave standard deviation decreasing from 1.141 m to 0.621 m under the very high sea state at 0° wave approach under wave-alone loading. Furthermore, buoyant-leg responses demonstrated a more balanced distribution of radial deformation under controlled conditions. The proposed LS-RCM provides an effective passive strategy for enhancing the operational safety and stability of BLSRP systems without requiring external power input.