Reliability Analysis And Safety Assessment Of A New Type Of SPAR Platform

A new concept deepwater floating platform, which has the advantage of improved safety and reliability, more integrating functionality, and better performance, is required, especially for such a platform integrating the key functions of drilling, dry-tree production, oil storage and offloading capabilities. This new concept Spar FPSO improves the flexibility of technical solution and decrease the overall development cost. Because the vertical dimension of the SDPSO platform is far greater than its horizontal dimension, it is not possible to prevent the bending moments in the structure during processes of transportation, installation and working. It is of great importance to study the bending strength and fatigue strength of the hull structure of the SDPSO platform.The research computed the hydrodynamics of the SDPSO platform by using SESAM/Wadam. With Standard Wave Data of the North Atlantic and P-M wave spectrum, a set of process was proposed to calculate the distribution of extreme wave bending moment. Usage of ABAQUS software to calculate the extreme bending moment of mid tank. Explicit dynamic step was applied. Obtain the probability distribution of the ultimate strength of the SDPSO platform by using developed Rosenblueth method, with material yielding stress and thicknesses of important shells as random variables.According to the results of extreme wave bending moment and ultimate strength, the research applied reliability method to evaluate the safety and reliability of the SDPSO platform. Combining hot stress method, S-N curve, spectral analytical method and fatigue accumulation damage theory, the fatigue life of key node of the hull structure was analyzed. Computation of the reliability index and fatigue failure probability taking uncertainty of fatigue accumulation damage, uncertainty of S-N curve, and uncertainty of stress calculation as the stochastic variables.