Global Structural Loads Induced by Abnormal Waves and Design Storms on a FPSO

The structural loads on a FPSO induced by a large set of realistic (measured) abnormal waves are compared with the loads induced by “design storms” and also with the minimum values required by Classification Society rules. The design storms have a duration of 3 hours and correspond to the 100 years contour of the scatter diagram of the Northern North Sea. Time domain simulations are performed with a time domain seakeeping program that accounts for the most important nonlinear effects. The results are analyzed to obtain probability distributions of the sagging and hogging peaks of the vertical bending moment. Several theoretical distributions are fitted to the simulated realizations.