Biomimetic Nonlinear X-Shaped Vibration Isolation System for Jacket Offshore Platforms

Vibrations induced by marine environmental loads can compromise the operational performance of offshore platforms and, in severe cases, result in structural instability or overturning. This study proposes a biomimetic nonlinear X-shaped vibration isolation system (NXVIS) to suppress earthquake-induced vibration responses in offshore platforms. The key difference between the novel isolator and traditional systems lies in the proposed NXVIS can be tailored to different load requirements and resonant frequencies to accommodate diverse offshore platforms and environmental loads. By adjusting isolator parameters (e.g., link length and spring stiffness, etc.), the anti-vibration system can achieve different types of nonlinear stiffness and a large-stroke quasi-zero stiffness (QZS) range, enabling ultra-low frequency (ULF) vibration control without compromising load capacity. To evaluate the effectiveness of the designed NXVIS for the vibration suppression of jacket offshore platforms under seismic loads, numerical analysis was performed on a real offshore platform and seismic loads. The results show that the proposed nonlinear vibration isolation solution significantly reduces the dynamic responses of deck displacement and acceleration under seismic loads, demonstrating effective low-frequency vibration control. This proposed NXVIS provides a novel and effective method for manipulating beneficial nonlinearities to achieve improved anti-vibration performance.