Nonlinear Response of Steel Fixed Offshore Platform

What is it about?

The structural design requirements of a fixed offshore platform subjected to wave-induced forces and moments in steel jacket can play a major role in the design of the offshore structures. For an economic and reliable design, good estimation of wave loadings is essential. Wave plus current kinematics are generated using fifth-order Stokes wave theory. The horizontal components of the wave velocity and acceleration fields are multiplied by a wave kinematics factor that is intended to account for direction spreading and irregularity of the wave profile. The wave and current forces acting on the member is computed using Morison’s equation, which decomposes the total force into an inertia component and a drag component. A nonlinear response analysis of a fixed offshore platform under wave loadings is presented; the structure is discretized using the finite element method. The dynamic response of fixed offshore structure together with the distribution of displacement, axial force, and bending moment along the leg is investigated for regular and extreme conditions, where the structure should keep production capability in conditions of the 1-year return period wave and must be able to survive the 100-year return period storm conditions. The result of the study shows that the nonlinear response investigation is quite crucial for safe design and operation of offshore

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