INFLUENCE OF X DIRECTION MOTION OF THE SUSPENSION POINT AND RIGID BODY SWING ON THE DISPLACEMENT OF A STEEL CATENARY RISER UNDER WAVE ACTION

The response and force effect of rigid body swing (RBS) on transverse flow direction is not negligible.Based on slender beam model, wave action (WA), RBS model and in-line movement of suspension point (TSM) are simulated.And structural response effect of RBS is simulated and estimated.The simulation and evaluation display that in terms of overall motion pattern, response in xy plane develops gradually from a narrow swing in x direction to a narrow swing in y direction.It is important to consider a particular location conservation of energy in three directions with water depth.As water depth increases, displacement and main frequency decrease.The decrease amplitude is strongest or most severe in top suspension region.For the spectrum analysis, the response main frequency and wave frequency are very close, and the motion is a forced motion.As water depth increases, the main frequency first increases then decreases.The trend is similarly to corresponding response change and contrary to energy or amplitude of xy plane change.As the energy decreases and then increases in xy plane, the z direction increase of RBS presents the opposite change in three directions.The effect of RBS on structural response can reach 20% after simulation.The effect of RBS is different from that of WA and TSM, which decreases with depth increase.And RBS is positively correlated to vector diameter S. It is expected that analysis and study may provide some advice for simulation of SCR and its RBS.