6-DOF Motion Assessment of A Hydrodynamic Numerical Simulation of A Semisubmersible Platform Using Prototype Monitoring Data

Hydrodynamic numerical simulations are used to conduct structural analyses and inform the design of engineered marine structures. In this paper, a hydrodynamic numerical model of "Nanhai Tiaozhan" (NHTZ) FPS platform was established according to its design specifications. The model was assessed with two sets of field monitoring data representing harsh and conventional sea states. The motion responses of the platform according to the measured data and the hydrodynamic simulation were compared by reviewing their statistical characteristics, distributions, and spectrum characteristics. The comparison showed that the hydrodynamic model could correctly simulate the frequency domain characteristics of the motion responses of the platform. However, the simulation underestimated the reciprocating motions of the floating body and the influence of slow drift on the motion of the platform. Meanwhile, analysis of the monitoring data revealed that the translational degrees of freedom (DOF) and rotational DOF of the platform were coupled, but these coupled motion states were not apparent in the hydrodynamic simulation.