Leg-specific deterministic extreme wave response analysis of offshore fixed platform jacket

For a dynamic in-service analysis fixed platform offshore jacket hit by waves and current in only one direction being extreme case, a leg specific displacement time history has been obtained to check for the effects of one leg on the other with possible phenomenon of diffraction, wave scattering, or reflection of waves. Wave acting on the platform having variable water depth, wave length, wave height and time period applied and analyzed on SACS. The primary objective of in-service analysis was reached by multiple pre-analysis such as pile-soil linearization, creation of super element, basis static analysis, and Eigen value analysis for natural frequency of the structure using different module of SACS. Finally, conducting extreme wave dynamic analysis using Stokes fifth order wave theory and deterministic wave approach to record global and local behavior of the jacket. To keep the analysis as useful as possible, some environmental loads and contingencies has been used in this report such as marine growth, corrosion allowance, etc. The local behavior presenting an overall displacement and direction of the top of deck at instances of wave phases presented in this report. Base shear is also extracted at the mudline with overturning moment on the mudline globally. Wave forces generated by the software are calculated by appropriate theory presented in this report. The directional wave force creating extreme response in terms of displacement is shown in this report. Moreover, to check diffraction and wave scattering, a hypothetical wave of wave length shorter than the extreme waves and not larger than the spacing between legs adjacent to each other and diagonally has been applied on the jacket which shows a decreased top of the deck displacement. The results can be concluded from deck displacement time history, while for a very specific response more research is to be conducted assessing response along the height of the jacket legs and deck.