Stochastic fatigue approach has been presented for the topside process platform structure on floating units such as FPSO and FLNG. The methodology implies that the topside and hull structure are modeled in an integrated model and solved through finite element hydro-structural solver. With reference to a real project, the result compared with simplified and more conservative approach demonstrating the engineering added value with a fit for purpose methodology.

With full integrated model, the correct capture of inertia and deflection and considering wave spectra applied to the response function in full range of applicable waves, a proper fatigue damage for each probable wave calculated which in sum concludes about the total fatigue damage with neither any fatigue contribution overlooked, nor any unnecessary conservatism taken. Such approach is very effective to find out real critical fatigue spots helping for an effective engineering effort and schedule target achievement.

The full practical workflow involving naval and structural discipline is presented and with reference to a real project experience which implemented the presented methodology, the effectiveness to narrow down the fatigue concerned spots are reviewed. Meanwhile some hints about susceptible spots subject to fatigue on a floating production unit are provided.

The workflow as proposed aims to connect and integrate naval and structural expertise using synergy between offshore and shipbuilding industry. Meanwhile the results of the proposed method will provide more clarity about the effects of integrated modeling and stochastic fatigue method for the offshore floating units.

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