Cylindrical hull structural arrangement

Abstract

An improved floating circular hull construction arrangement. The hull is divided into sections by watertight flats. The flats are stiffened with angles or bulb tees curved to form concentric circles that are in turn supported by the radial girders spaced around the flats and spanning between the inner and outer-shells. In each section, longitudinal girders spaced radially around the inside of the outer-shell terminate at the flats and attach to the flats and do not penetrate the flats. The longitudinal girders are attached to flats aligned with the locations of the radial girders that extend across the flats to the inner and outer shells. A panel stiffening arrangement on the inner circumference of the outer shell is attached to the outer shell and the longitudinal girders. Longitudinal girders spaced around the outer circumference of the inner shell extend along the length of the inner shell and are attached to the radial girders. With the inner and outer longitudinal girders connected to the radial girders, moment resisting frames are created that are arranged radially in each compartment. These frames stiffen the individual girders as well as balance the differential axial loadings in the inner shell and outer shell surfaces. The compartments are assembled with the sections in a vertical orientation to minimize self-weight distortion during erection and to provide direct access with shop cranes during assembly of the full sections. The completed sections are rotated to the horizontal to be joined to the other sections to form a complete cylinder.

Description

[0001] related application [0002] This application is related to and claims the benefit of Provisional Application Serial No. 60 / 654,994, filed February 22,2005. technical field [0003] The present invention relates generally to floating offshore structures, and more particularly to cylindrical hulls or cylindrical portions of hulls. Background technique [0004] The offshore oil and gas industry uses various forms of floating systems to provide "platforms" from which to drill and produce hydrocarbons at water depths that are relatively low for fixed platforms, offshore rigs, and other bottom-building systems. Not economically or technically feasible. The most common floating systems used for these purposes are Spar platforms (Spars), tension post platforms (TLPs), semi-submersible platforms (Semis) and traditional bridge structures (Ships). All of these systems use some form of stiffener structure to form their housings. In a broad sense, the invention applies general...

AI Technical Summary

Problems solved by technology

While the sections are naturally rigid when made as a sector in a jig, making them suitable for carrying loads from horizontal assemblies, this rigidity is not suitable for the flexibility to fit the sections together

The result is a contradiction in terms of rigidity requirements for erection and preparation, complicating the assembly process

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