SIMULATION OF RINGING IN OFFSHORE SYSTEMS UNDER VISCOUS LOADS

In recent years, significant interest has been shown in identifying th e nonlinear mechanisms that induce ringing in complex offshore structu ral systems. This high-frequency transient-type response has been obse rved in offshore systems, particularly in tension leg platforms (TLPs) . Given the implications of this behavior on the fatigue life of TLP t endons, it is essential that ringing be considered in the overall resp onse evaluation. This study uses a simplified structural model exposed to viscous-type loading to demonstrate several of the salient feature s observed in higher-order potential-type wave-induced loads. Ringing response in pitching mode caused by viscous-type loading is simulated on a cylinder piercing the water surface, and significant mechanisms r eponsible for inducing ringing are delineated. Results clearly indicat e that, under certain conditions, ringing-type response characteristic s are captured under viscous-type loading. The cylinder characteristic s are varied to ameliorate the system performance by altering the cond itions conducive to ringing.