Floating buoy fatigue analysis for barge-to-ship operations. (15th June 2023) - Cabral, Weverton
Abstract: Transshipment operations around the world are in high demand, notably so in the Amazon. Usually, this type of operation occurs with mooring buoys. In Brazil, transshipment operations are handled with temporary use contracts of a maximum of 4 years. An adaptation of a method for fatigue analysis of this type of structure is proposed. This method uses computational modeling and simulation via the FEM, focusing on the points of greatest cyclical loading of the padeye, to estimate the useful life of this structural component through S–N curves and internationally recognized regulations. Thereunto, the main tensions in the buoy are obtained from the application of calculated forces for traction on a mooring cable at the bitt of the buoy, whose magnitudes satisfy ranges validated by means of instrumentation on board. The limitations of the method are based on environmental conditions corresponding to a river region with no tidal influence, a fact that allows simplification regarding the influence of waves. The results indicate that regular loads acting on the padeye can ensure a useful life as if the component were a medium-term anchored system since the minimum fatigue life for an applied load of 30 tf is 7.66 years. Highlights: Direct transshipment to Largo is an alternative for handling solid bulk. Mooring buoys will be increasingly used for offshore transshipment operations. An adaptation of a method for fatigue analysis via FEM was proposed. Hot-spot stresses and S–N curves allowed estimating the fatigue life of the padeye. This can indicate specific laws and regulations for offshore transshipment.