Numerical investigation of the specific roll-heave coupled motion in an elastically connected twin barge float-over system

The concept of using an elastic connection between twin barge hulls and topsides offers an advantage in reducing the contact forces and topsides loads in a twin barge float-over (TBFO) system. However, due to the insufficient understanding of the complex motion characteristics of elastically connected multi-body systems, this operational mode has not yet been applied in marine engineering. To investigate the coupled motion characteristics of an elastically connected TBFO system, an experimental study was conducted. The results indicated that the topside's roll motion in such systems is greater than that of the barges under low-frequency wave conditions. Furthermore, a strong coupling exists between the topside's heave motion and the reverse roll motion of the twin barges. A numerical model for the TBFO system with elastic connections was developed and validated against physical model test results. Further numerical analysis revealed that the specific roll-heave coupled motions increase the topside's heave motion at low frequencies while reducing it in the higher frequency range. This suggests that the elastic connection could be effectively applied in TBFO operations under relatively short-wavelength sea conditions.