Arctic offshore platform

Claim 2

An offshore structure for use in arctic water containing moving ice masses comprising: a frustum base section and a circular upper section, said base section having sufficient height to extend above the surface of the water; the skin of said frustum section having a controlled stiffness cellular structure formed by an outer plate member and an inner plate member, said outer and inner plate members being separated by a series of radial and meridional webs fastened to said plates to form a cellular structure; and a flexible beam structure, said beam structure being formed by a series of circumferential beams supported by a series of radial bulkheads projecting upward from the bottom of said frustum, said skin being attached to said flexible beam structure intermediate said radial bulkheads.

Claim 3

A frusto-conical base member for use in an offshore structure for conducting operations in arctic waters having moving ice, said base member comprising: a solid circular bottom; an outer skin for said base, said outer skin being formed by a solid outer plate and a solid inner plate, said inner and outer plates having a general conical shape and radially spaced, a plurality of meridional web members positioned between said inner and outer plates and fasten thereto to maintain the spacing between said plates; a plurality of radial bulkheads attached to said bottom and terminating short of said outer skin; and a plurality of horizontal flexible beams, said beams being secured between said radial bulkheads to form a series of vertically spaced substantially circular beams, said beams supporting said outer skin at points intermediate said bulkheads.

Claim 4

A frusto-conical base member for use in an offshore structure for conducting operations in arctic waters having moving ice, said base member comprising: a solid circular bottom; an outer skin for said base, said outer skin being formed by a solid outer plate and a solid inner plate, said inner and outer plates having a general conical shape and radially spaced, a plurality of meridional web members positioned between said inner and outer plates and fasten thereto to maintain the spacing between said plates; a plurality of radial bulkheads attached to said bottom and terminating short of said outer skin; and a plurality of horizontal flexible beams, said beams being secured between said radial bulkheads to form a series of vertically spaced substantially circular beams, said beams supporting said outer skin at points intermediate said bulkheads.

Claim 5

The base member of claim 2 wherein in addition to said meridional members a series of circumferential webs are positioned between said inner and outer plates and fastened thereto.

Claim 6

The base member of claim 3 and in addition secondary stiffening webs, said webs being attached to the outer shell and positioned between said meridional members.

Claim 7

The base of claim 4 wherein said inner plate is provided with a series of load transfer boxes that project inwardly from said inner plate, said load transfer boxes having a flat surface that contacts said beams at approximately the center thereof.

Claim 8

The base member of claim 5 wherein said box has a parallelogram cross section.