A semi-submersible wind turbine platform is capable of floating on a body of water and supporting a wind turbine, and includes a keystone. At least three bottom beams extend radially outward of the keystone, and a center column extends perpendicularly from an upper surface of the keystone, a first axial end of the center column attached to the keystone; the center column configured to have a tower attached to a second axial end thereof. One of a plurality of outer columns extends perpendicularly from an upper surface of each bottom beam, wherein first axial ends of the outer columns are attached to a distal end of each bottom beam. One of a plurality of top beams extends between a second axial end of each outer column and a second axial end of the center column, wherein the top beams are configured substantially not to resist bending moment of a tower attached to the center column.

A semi-submersible wind turbine platform is capable of floating on a body of water and supporting a wind turbine, and includes a keystone. At least three bottom beams extend radially outward of the keystone, and a center column extends perpendicularly from an upper surface of the keystone, a first axial end of the center column attached to the keystone; the center column configured to have a tower attached to a second axial end thereof. One of a plurality of outer columns extends perpendicularly from an upper surface of each bottom beam, wherein first axial ends of the outer columns are attached to a distal end of each bottom beam. One of a plurality of top beams extends between a second axial end of each outer column and a second axial end of the center column, wherein the top beams are configured substantially not to resist bending moment of a tower attached to the center column.

A method of constructing and assembling a floating wind turbine platform includes constructing pre-stressed concrete sections of a floating wind turbine platform base, assembling the floating wind turbine platform base sections to form the base at a first location in a floating wind turbine platform assembly area, and moving the base to a second location in the floating wind turbine platform assembly area. Pre-stressed concrete sections of floating wind turbine platform columns are constructed, and the column sections are assembled to form a center column and a plurality of outer columns on the base to define a hull at the second location in the floating wind turbine platform assembly area. The hull is then moved to a third location in the floating wind turbine platform assembly area. Secondary structures are mounted on and within the hull, and the hull is moved to a fourth location in the floating wind turbine platform assembly area. A wind turbine tower is constructed on the center column, and a wind turbine is mounted on the wind turbine tower, thus defining the floating wind turbine platform. The floating wind turbine platform is then moved to a launch platform in a fifth location and launched into a body of water.

The floating body structure is a floating body structure that supports an object to be supported so that the object to be supported floats in the sea, including a floating body section connected to a base end portion of the object to be supported, wherein the floating body section has a lid body made of steel, an outer pipe made of steel, and an inner pipe made of steel and provided inside the outer pipe, and the floating body section is hermetically sealed by the lid body in a state where at least a portion of a gap formed between an outer wall surface of the inner pipe and an inner wall surface of the outer pipe is filled with concrete or mortar.

The floating body structure is a floating body structure that supports an object to be supported so that the object to be supported floats in the sea, including a floating body section connected to a base end portion of the object to be supported, wherein the floating body section has a lid body made of steel, an outer pipe made of steel, and an inner pipe made of steel and provided inside the outer pipe, and the floating body section is hermetically sealed by the lid body in a state where at least a portion of a gap formed between an outer wall surface of the inner pipe and an inner wall surface of the outer pipe is filled with concrete or mortar.

A semi-submersible platform for supporting wind turbines comprising a mixed structure with two portions: a first concrete caisson-type structure, which serves as hydrodynamic stability and flotation of the platform, consisting of: a hollow, closed base plate, and cylindrical and/or frustoconical-shaped bodies, the bases of which are embedded in the base plate, in areas close to the vertices thereof, which are closed at the top by covers; and, a second structure formed by a transition piece that connects the base plate to the lower end of the tower of the wind turbine at connection points, located on each side of the base plate, distributing the service loads of the wind turbine towards the concrete caisson-type structure.

A semi-submersible platform for supporting wind turbines comprising a mixed structure with two portions: a first concrete caisson-type structure, which serves as hydrodynamic stability and flotation of the platform, consisting of: a hollow, closed base plate, and cylindrical and/or frustoconical-shaped bodies, the bases of which are embedded in the base plate, in areas close to the vertices thereof, which are closed at the top by covers; and, a second structure formed by a transition piece that connects the base plate to the lower end of the tower of the wind turbine at connection points, located on each side of the base plate, distributing the service loads of the wind turbine towards the concrete caisson-type structure.