Análise global de fadiga em linhas de ancoragem considerando ultra-baixas frequências de dados de movimentos medidos

Abstract

The present work aims to identify and quantify very low frequency motions for a certain oil platform, as well as to evaluate their contribution to the total fatigue damage in mooring lines. Such motions, above the second order, would have very long periods, not being detected by a three-hour analysis window. On the other hand, as longer period motions are considered, it is also expected larger displacements and, in consequence, a larger tension variation. Through time-domain dynamic analyses performed with the SITUA/PROSIM software, utilizing motion data from field measurements, the fatigue damage for the higher order motions (named ultra-low frequencies motions) was compared to the total damage assessed in the lines. In the end, there was also an analysis for the damage generated by the displacements obtained from field data.