Dynamic analyses and preliminary design of offshore triceratops in ultra-deep waters

Abstract

More adaptable geometric form of offshore platforms, counting on the benefits of form-dominant design, is effective to encounter various environmental loads. Offshore triceratops is a new-generation offshore platform, whose conceptual design showed good degree-of-adaptability to ultra-deep-water conditions. Deck is partially isolated from the buoyant legs by ball joints by allowing transfer of partial displacements of buoyant legs to deck but restraining transfer of rotational responses. Prior to the suitability assessment of triceratops for ultra-deep waters, detailed dynamic analysis on the preliminary geometric form is necessary as a proof of validation for design applications. Current study discusses a detailed numeric analysis of triceratops at 2400 m water depth under regular and irregular waves; preliminary design of both buoyant legs and the deck is also presented. Buoyant Legs are designed as stiffened cylinders and the deck is designed as the integrated truss system. In compliant structures, the role of tethers is of paramount importance. Hence, the stress analysis and fatigue analysis of the tethers are also carried out to assess the service life of the structure. Presented study shall aid offshore engineers and contractors to understand suitability of triceratops, in terms of design and dynamic response behaviour.