Tubular elements for floating offshore support structures used in wind turbines

Abstract

A method for forming a tubular element used as a longitudinal section of a strut in a truss structure for a floating offshore support structure for wind turbines, the method comprising: providing four elongated flat steel plates, each extending longitudinally and having two opposing lateral edges; deforming each plate such that its cross-sectional shape smoothly transitions between a straight shape and an arcuate shape along the longitudinal direction; and forming the tubular element by interconnecting the four deformed plates along their lateral edges. The interconnecting plates each form a corresponding circumferential section of the tubular element, wherein the cross-sectional shape of the tubular element smoothly transitions from a circular shape to a rectangular shape along the longitudinal direction. The tubular element can connect the strut to another cylindrical tubular element and another portion of the floating offshore support structure.

Description

Technical Field

[0001] This invention relates to a method for forming a tubular element used as a longitudinal section of a strut in a truss structure for a floating offshore support structure for a wind turbine. The invention further relates to: the tubular element formed by the method; a strut comprising the tubular element; a floating offshore support structure comprising the strut; a wind turbine having the floating offshore support structure; an offshore wind farm comprising the wind turbine; and a method for assembling the floating offshore support structure. Background Technology

[0002] Offshore support structures, such as semi-submersible or floating offshore support structures for wind turbines, are known in themselves, for example, through WO2022 / 086329A1. Such offshore support structures typically comprise a truss structure containing several tubular struts as truss members. Floating offshore support structures are typically constructed onshore or at an offshore construction site before being transported to an offshore use location, such as an offshore wind farm site, where the support structure is buoyant to buoyantly support the wind turbine supported thereon, particularly using semi-submersible columns for buoyancy.

[0003] During construction, struts typically must be welded to other components, such as semi-submersible columns and / or wind turbine receiving elements, at one or more of their ends to form a robust and durable structure. Achieving these connections efficiently and effectively is often challenging, especially given the typically large size of floating offshore support structures. For example, some struts may need to be connected while held at a height of approximately 35 meters above the ground, for example, via cranes and / or temporary support frames. Meanwhile, to facilitate welding, struts often must be positioned with extreme precision relative to the components to which they are to be connected. Even with precise positioning, welding can still be complex, for example, when constraints require welding to be performed from below non-vertical direct seams, creating adverse gravitational effects on the safety of the welding and the welding process.

[0004] Based on the above, improvements are needed. Summary of the Invention

[0005] The object of this invention is to at least partially address at least one of the challenges mentioned above, or related challenges. The object of this invention is to provide a floating offshore support structure for wind turbines that is sufficiently robust, durable, and relatively economical, especially in terms of construction. The object is to at least provide an alternative.

[0006] The present invention is based, at least in part, on the unexpected discovery that the aforementioned challenges can be addressed using the end section of a strut in the form of a tubular element, which presents a transition between a circular cross-sectional shape at a position closer to the strut (i.e., more towards the longitudinal center of the strut) and a rectangular cross-sectional shape at a position further to the strut (i.e., more towards the longitudinal end of the strut). Specifically, the circular cross-sectional shape allows the strut to have a circular cross-sectional shape for most of its length, while the rectangular cross-sectional shape facilitates welding of the strut end to another element. More specifically, the rectangular cross-sectional shape allows welding to be performed relatively safely and efficiently: the two vertical sides and the bottom side of the rectangle can be welded from within the tubular strut, and the top side of the rectangle can be welded from a partially flat top surface of the strut.

[0007] Based on this discovery, the present invention provides a strut for a truss structure of a floating offshore support structure for wind turbines, the strut comprising a tubular element as a longitudinal section of the strut, wherein the cross-sectional shape of the tubular element transitions from a circular shape to a rectangular shape along the longitudinal direction of the tubular element.

[0008] Preferably, the aspect ratio of the rectangular cross-section is in the range of 2:1 to 1:2, more preferably in the range of 3:2 to 2:3, and even more preferably in the range of 4:3 to 3:4, for example, in the range of 5:4 to 4:5. Therefore, the rectangular shape can be a square shape or a different rectangular shape. This type of tubular element can be commonly referred to as a round-to-square tubular element, even if the rectangular shape is not square in form. In this context, it should be understood that the expressions "rectangular shape" and "square shape" encompass shapes that deviate slightly from a perfect rectangle or square, such as a slightly trapezoidal rectangular shape. Therefore, the expression "rectangular shape" can be understood as a quadrilateral shape where all four vertices correspond to right angles or near-right angles, for example, angles in the range of 80 degrees to 100 degrees, or in the range of 85 degrees to 95 degrees.

[0009] In this context, expressing a circular cross-sectional shape should be understood as approximating a perfect circle to a degree that is reasonably achievable under given conditions and / or reasonably meaningful in terms of load transfer in a truss structure. For example, in the case where a circular cross-sectional shape is formed by bending a plate at discrete locations corresponding to circumferential positions along the circular cross-sectional shape, the resulting curvature may vary slightly along the circumference while still obtaining an overall cross-sectional shape that a person skilled in the art would consider to be circular in this context. As another embodiment, it should be understood that struts and tubular elements may undergo some deformation under load (including under their own weight), which may cause the cross-sectional shape, such as a circular cross-sectional shape, to also be slightly deformed, for example, resulting in a slightly elliptical shape rather than a perfect circle. Therefore, in this context, expressing a circular cross-sectional shape may cover a deviation of up to 1%, 2%, or 5% from a perfect circle.

[0010] The transition between a circular and a rectangular cross-sectional shape is preferably smooth. This facilitates a relatively uniform force transmission along the longitudinal direction. In contrast, in known tubular elements, the transition between a circular and a rectangular cross-sectional shape is not smooth, especially exhibiting a so-called joint along the longitudinal direction, leading to potential weaknesses and uneven force transmission along the longitudinal direction. The present invention is also based, at least in part, on an unexpected discovery of how this drawback of known tubular elements can be overcome, particularly using the method of forming tubular elements described below.

[0011] The tubular element is preferably formed by, or may be formed by, a method comprising: providing four elongated flat steel plates, each extending longitudinally and having two opposing lateral edges; deforming each plate such that its cross-sectional shape smoothly transitions between a straight shape and an arcuate shape along the longitudinal direction; and forming the tubular element by interconnecting the four deformed plates along their lateral edges. As part of the tubular element, the interconnected deformed plates are arranged such that each deformed plate forms a corresponding circumferential segment of the tubular element, and the cross-sectional shape of the tubular element smoothly transitions longitudinally from a circular shape (i.e., where the cross-sectional shape of the deformed plate is arcuate) to a rectangular shape (i.e., where the cross-sectional shape of the deformed plate is straight).

[0012] In this context, a smooth transition between cross-sectional shapes along the longitudinal direction can be understood as a transition without longitudinal shape discontinuities, such as so-called joints or similar corners. If present, such discontinuities are typically observed as corners in the shape of the longitudinal section of the corresponding element. Such discontinuities are common in known round-to-square tubular elements, leading to uneven force transmission and potential weaknesses as explained above.

[0013] It has been found that the method for forming tubular elements described above advantageously enables the formation of tubular elements with such smooth transitions in cross-sectional shape, particularly in a relatively economical manner, thereby producing particularly effective and economical tubular elements for struts, which may be free of longitudinal shape discontinuities, such as joints. Specifically, the tubular element can therefore include a smooth transition and can be formed from four initial plates, each of which can each form a corresponding side of a rectangular cross-sectional shape and a corresponding arcuate segment of a circular cross-sectional shape, for example, about 90 degrees, the resulting four arcuate segments together forming a circular cross-sectional shape. Each of the plates may itself be free of corners in the longitudinal direction, while the interconnecting lateral edges of the plates may each extend along a cornerless curve or line extending only in the non-circular direction.

[0014] It should be understood that a smooth transition between a rectangular cross-sectional shape and a circular cross-sectional shape does not necessarily require this smoothness to extend beyond the transition zone or even exist at the end of the transition zone. For example, at the end of the transition zone where one of the cross-sectional shapes is circular, a tubular element may connect to another cylindrical tubular element, wherein there may be a longitudinal discontinuity at the connection, which is visible as a corner in some longitudinal cross-sections. Such a corner (if present) may deviate from a level angle by up to 20 degrees, preferably by up to 15 degrees.

[0015] Preferably, interconnecting four deformable plates along their lateral edges involves welding adjacent plates together at least along the transition zone. This interconnection method provides particularly robust and durable tubular elements, especially since the plates are steel plates. When the tubular element has a circular cross-sectional shape, the edges of the plates are preferably welded together by butt joints. When the tubular element has a rectangular cross-sectional shape, the plates are preferably welded together by corner joints. At the midpoint of the transition zone, a weld joint of a corresponding intermediate type can be applied. Additional types of weld joints, such as T-joints, can be applied, as will be further explained elsewhere herein.

[0016] Preferably, each of the four deformable plates extends beyond the end of the transition zone in the longitudinal direction at the longitudinal side of the plate's cross-sectional shape transition zone where the plate's cross-sectional shape is straight. The interconnected deformable plates can then be arranged such that the tubular element extends beyond the end of the transition zone in the longitudinal direction at the longitudinal side of the tubular element's cross-sectional shape transition zone where the tubular element's cross-sectional shape is rectangular.

[0017] Advantageously, tubular elements and struts can be connected to another element of the truss structure at a distance from the end of the transition zone, which has a rectangular cross-sectional shape, wherein such connections can be formed at the corresponding end of the tubular element extending longitudinally beyond the transition zone. This allows the tubular element to be cut to size during the construction of the truss structure, particularly to fit the length and / or the shape and position of the end to be connected, without affecting the transition. Furthermore, this allows welded connections between adjacent plates to form corner joints at the end of the transition zone, while forming potentially stronger T-joints at the end of the tubular element. Between the transition zone and the end of the tubular element, the tubular element can have a rectangular cross-sectional shape, which can be constant or variable, for example, along the longitudinal direction between the transition zone and the end of the tubular element.

[0018] Preferably, a smooth transition zone of the cross-sectional shape of the tubular element is matched at the longitudinal side of the transition zone where the cross-sectional shape of the tubular element is rectangular, with a constant or smoothly varying cross-sectional shape of the tubular element adjacent to the transition zone, so as to provide continuous smoothness across the respective ends of the transition zone in the longitudinal direction, wherein the plates are deformed and arranged to each other to provide this match.

[0019] In this way, the ends of the transition zone, where the cross-sectional shape is rectangular, correspondingly provide the smooth transition itself, as discussed above. In contrast, known round-to-square tubular elements typically have longitudinal shape discontinuities at such ends of the transition zone, especially in the form of joints.

[0020] Preferably, in order to provide this match, the plates are deformed and arranged such that the plates bulge outward along the transition zone at their interconnecting lateral edges, especially compared to an imaginary straight line that interconnects the circular and rectangular shapes at positions corresponding to the respective lateral edges.

[0021] Using this protrusion, the lateral edges of the plate can be smoothly formed in the longitudinal direction, wherein the smoothness can continue across the transition zone where the cross-sectional shape of the plate is a straight shape at the end, for example, continuing all the way to the longitudinal end of the plate.

[0022] Preferably, on the side of the transition zone where the tubular element has a rectangular cross-sectional shape, adjacent plates in the interconnected deformable plates extend at right angles to each other along the circumferential direction of the tubular element, particularly conforming to a rectangular shape. Preferably, on the side of the transition zone where the tubular element has a circular cross-sectional shape, adjacent plates in the interconnected deformable plates extend at flat angles to each other along the circumferential direction of the tubular element at least at the lateral edges of the interconnection, particularly conforming to corresponding local tangents of the circular shape at the lateral edges of the interconnection.

[0023] Preferably, along the transition zone, the angles between the plates at the interconnecting lateral edges gradually and monotonically change between right angles and straight angles. This gradual monotonous change advantageously contributes to the overall smoothness of the transition.

[0024] Preferably, at least along the transition zone, the longitudinal centerline of the plate remains undeformed by the deformation of the plate. Advantageously, such a centerline can provide a straight force transmission in the longitudinal direction.

[0025] Preferably, for each of the plates, the triangular segments of the plate remain undeformed by deformation of the plate, and the triangular segments are defined by a triangular base and a triangular apex. The triangular base preferably corresponds to the straight cross-sectional shape of the plate at the end of the transition zone where the cross-sectional shape of the tubular element is rectangular. The triangular apex preferably corresponds to the intersection of the longitudinal centerline of the plate and the arcuate cross-sectional shape of the plate at the end of the transition zone where the cross-sectional shape of the tubular element is circular.

[0026] This method can provide relatively robust and stable tubular elements. At the same time, the required deformation of the plate can therefore be relatively limited, thus allowing for relatively easy formation of tubular elements.

[0027] Preferably, along the transition zone, the triangular section is the only section of the plate that remains undeformed by the deformation of the plate before the interconnection of the deformed plates.

[0028] In this way, the transition between the arcuate cross-sectional shape and the straight cross-sectional shape of the plate can be achieved particularly effectively, for example by gradually bending away from the lateral side of the triangle through symmetrical or near-symmetrical deformation relative to the center line, so as to form an arcuate cross-sectional shape at the longitudinal position corresponding to the tip of the triangle.

[0029] Preferably, when viewed in the longitudinal direction, the circular cross-sectional shape does not extend beyond the rectangular cross-sectional shape. The sides of the rectangular cross-sectional shape may, for example, correspond to the corresponding tangents of the circular cross-sectional shape.

[0030] In this way, the undeformed centerline and triangular sections mentioned above can be incorporated into the design of tubular elements.

[0031] Preferably, the method further includes attaching one or more reinforcing structures to the tubular element inside the tubular element, particularly where the tubular element has a rectangular cross-sectional shape.

[0032] In this way, the stability and strength of the tubular element can be improved, especially relative to a rectangular cross-sectional shape. Meanwhile, although reinforcing structures can also be applied elsewhere along the tubular element or strut, these may not be necessary due to the inherently greater stability and strength typically associated with the circular cross-sectional shape of the tubular element.

[0033] Preferably, the deformation of the plate is limited such that the deformable plate, as a surface, is a deployable or simply bendable surface. Preferably, the deformation of the plate is limited such that the deformable plate does not contain any joints. Preferably, the deformation of the plate is limited to prevent the deformable plate from having any radius less than ten times the local thickness of the plate. Preferably, the deformation of the plate is limited to prevent any deformation of the plate that results in a local elongation greater than 5% of the steel sheet material containing the plate.

[0034] Such restrictions on plate deformation can advantageously promote relatively uniform force transmission through the plate and the strength of the plate as a tubular element, especially when used as a strut. Specifically, this can thus limit the weakening of the steel plate material due to deformation and prevent unfavorable large stresses in the steel plate material. In this context, a smooth shape transition can be understood as conforming to one or more of these restrictions on the plate, and / or conforming to one or more of the corresponding restrictions on the tubular element.

[0035] Preferably, the tubular element is formed without any joints relative to the longitudinal direction. Preferably, the deformable sections of the plate are shaped according to the corresponding conical surfaces that define imaginary inclined cones having apexes located outside the transition zone and / or the longitudinal and / or lateral extent of the plate. Preferably, the base of the imaginary inclined cone corresponds to the end of the transition zone having a circular cross-sectional shape. Preferably, the position of the apex coincides with the imaginary extension of the triangular side of a preferred flat, undeformed triangular section of the plate.

[0036] In this way, unfavorable high stresses in tubular elements can be prevented, especially in sections used as struts. Specifically, the arrangement of the hypothetical inclined cones advantageously allows for the aforementioned better limitation of plate deformation. In contrast, it is known that tubular elements are essentially shaped with a cone or similar apex that coincides with the end of the transition zone, thereby locally resulting in an excessively small radius of the plate material.

[0037] Preferably, the intersection of the ends of the tubular elements in the transition zone, where the interconnecting lateral edges of the plates have a rectangular cross-sectional shape, is located at less than 90% of the distance from the base to the apex of the imaginary tilted cone, more preferably less than 80%, more preferably less than 70%, and even more preferably less than 60%. In this way, the advantages of the arrangement of the imaginary tilted cone mentioned above can be achieved to a particularly large extent.

[0038] Preferably, the tubular element, particularly on the side of the transition zone where the cross-sectional shape of the tubular element is rectangular, forms a connector structure for connecting the strut to another part of the floating offshore support structure, particularly at the longitudinal end of the strut.

[0039] Such connector structures can advantageously facilitate the construction of truss structures and / or floating offshore support structures. For example, a connector structure can be configured to engage with a matching connector structure that can be disposed on a column assembly of a floating offshore support structure, allowing the struts to form truss members of the truss structure. As explained elsewhere herein, each connector structure may present straight plate edges to facilitate welding.

[0040] Preferably, the strut further includes another cylindrical tubular element as another longitudinal section of the strut, the other cylindrical tubular element being connected to the tubular element at one side of the transition zone where the cross-sectional shape of the tubular element is circular.

[0041] In this way, the advantages of using cylindrical tubes as part of the truss structure can be applied to the struts. This includes, in particular, a relatively high strength-to-weight ratio. Furthermore, when connected, additional cylindrical tubular elements can act as reinforcing structures for the tubular elements. These additional cylindrical tubular elements preferably have a larger longitudinal dimension than the tubular elements, particularly forming a large portion of the strut's length. The additional cylindrical tubular elements are preferably welded to the tubular elements.

[0042] Preferably, the circular cross-sectional shape of the other cylindrical tubular element matches the circular cross-sectional shape of the tubular element.

[0043] Thus, the circular cross-sectional shape of the tubular element can be essentially continued by another cylindrical tubular element.

[0044] On the other hand, an offshore support structure for wind turbines is provided, comprising struts as described herein. The offshore support structure is preferably a floating offshore support structure. In this context, a floating offshore support structure should be understood as a support structure having its own floating capability to float during normal use while performing its supporting function, such as by supporting wind turbines thereon. This floating capability can be provided, in particular, by semi-submersible columns as described herein.

[0045] Such offshore support structures can provide advantages that substantially correspond to those described above for struts. Specifically, the offshore support structure can thus benefit from the advantages provided by the tubular elements described. The struts can particularly form truss members as part of the truss structure of the floating offshore support structure, especially horizontal or diagonal truss members.

[0046] The truss structure and / or connecting structures that may form part of the truss structure preferably interconnect two, three, or more column assemblies of the floating offshore support structure, each column assembly comprising a corresponding semi-submersible column. A strut may be connected to at least one of the column assemblies, particularly at the end of the strut. At the connection to the column assembly, the strut may have a rectangular cross-sectional shape, particularly formed by a tubular element in the transition zone on one side where the tubular element has a rectangular cross-sectional shape.

[0047] Preferably, especially when the strut is used to form horizontal or diagonal truss members, one or more interfaces between the column assembly and the strut (e.g., weldable plate edges) are slanted, particularly during the assembly of the floating offshore support structure, to provide space for maneuvering the ends of the strut into place substantially downstream. This facilitates relatively precise and well-controlled manipulation. It should be understood that the term slanted is used here relative to the orientation of the strut when used as a truss member. Thus, for example, in the case of use as a horizontal truss member (also referred to herein as a horizontal strut), the term slanted means an angle relative to a plane tangential to the longitudinal direction of the strut.

[0048] The column assembly and strut can be configured to help stabilize the strut relative to the column assembly before and / or during the formation of a connection between the column assembly and the strut, particularly by allowing the strut to be at least partially supported on the column assembly. Specifically, the aforementioned connecting structure (if present) can be configured to allow the connector structure of the strut to be at least partially supported on the connector structure of the column assembly.

[0049] Preferably, at the connection between the column assembly and the strut, the column has a polygonal, more preferably hexagonal, cross-sectional shape, and may have rounded vertices.

[0050] This type of cross-sectional shape makes the construction of columns and column assemblies relatively easy.

[0051] The strut is preferably connected to the column assembly at a circumferential position corresponding to the vertices of the polygonal shape of the column. In this way, the longitudinal force associated with the strut can be transferred relatively effectively to the column, and vice versa. Alternatively or additionally, the strut or another strut may be connected to the column assembly at different positions, such as circumferentially located between the vertices of the polygonal shape.

[0052] Preferably, the floating offshore support structure includes a damping box, particularly as part of the column assembly as mentioned above. The damping box may have a top plate and a bottom plate spaced apart from the top plate, wherein the top plate and the bottom plate are interconnected by one or more side plates.

[0053] Such damping boxes can advantageously promote low motion and acceleration in floating offshore support structures, especially in the case of semi-submerged offshore support structures.

[0054] The strut can be connected to the damping box. In this case, the strut is preferably connected to the damping box at one or more side plates, and in particular, it does not overlap with either the top plate or the bottom plate outside the damping box.

[0055] Thus, the longitudinal force associated with the strut can be transferred relatively effectively to the damping box, and vice versa.

[0056] Preferably, at the connection with the damping box, the strut has a rectangular cross-sectional shape, particularly formed by a tubular element in the transition zone on one side where the cross-sectional shape of the tubular element is rectangular.

[0057] This approach facilitates the construction of the connection between the strut and the damping box, especially in terms of welding.

[0058] Preferably, one straight side of the cross-sectional shape of the strut is aligned with or at least parallel to one of the top and bottom plates of the damping box, and preferably, the opposite straight side of the cross-sectional shape of the strut is aligned with or at least parallel to the other of the top and bottom plates of the damping box.

[0059] This arrangement can advantageously facilitate efficient force transmission between one strut and the top and / or bottom plate on the other side, wherein the top and / or bottom plate can in turn facilitate force transmission to another part of the column assembly.

[0060] On the other hand, a wind turbine is provided having a floating offshore support structure as described herein, wherein the wind turbine is supported on the offshore support structure, particularly when the offshore support structure is floating. On the other hand, an offshore wind farm is provided comprising at least one such wind turbine having an offshore support structure as described herein, wherein specifically, the offshore support structure is floating to support the wind turbine in a floating manner.

[0061] Such wind turbines and wind farms can benefit from the advantages described above regarding floating offshore support structures, truss structures, struts, and tubular elements. A wind farm can be considered a floating wind farm when it comprises multiple floating offshore support structures with wind turbines. Nevertheless, in some cases, offshore wind farms may comprise a combination of floating and non-floating support structures, for example, where sea depth varies across the wind farm.

[0062] The wind turbine is preferably supported on a truss structure and / or spaced apart from any semi-submersible columns of the floating offshore support structure. For such an arrangement, reference is made herein to WO2022 / 086329A1, which explains the associated advantages and possible details. For example, as explained therein, and as applicable to the context of this invention, the wind turbine may be supported on a wind turbine receiving element, which may be positioned on one of three preferred outer sides of the floating offshore support structure, between two semi-submersible columns, wherein said three outer sides may be defined by a truss structure serving as a connecting structure.

[0063] Preferably, the floating offshore support structure floats to support the wind turbine. For this purpose, as explained elsewhere herein, the floating offshore support structure has a floating capability, for example, it is semi-submersible, particularly using semi-submersible bollards as described herein. During use, the floating offshore support structure is preferably anchored to substantially maintain its position.

[0064] On the other hand, a method for assembling a floating offshore support structure as described herein is provided. The assembly method includes: providing at least two, preferably three, column assemblies, each column assembly comprising a corresponding semi-submersible column; providing at least one strut as described herein; and interconnecting at least two column assemblies by a truss structure comprising at least one strut, particularly as a corresponding at least one truss member.

[0065] Such methods advantageously enable the assembly of floating offshore support structures as described herein, particularly in a relatively economical manner, wherein column assemblies can be arranged and interconnected, for example, primarily by truss structures as described in WO2022 / 086329A1, but with the additional advantages associated with struts as described in this disclosure.

[0066] Preferably, the interconnection of at least two column assemblies includes connecting (in particular welding) the end of at least one strut to one of the column assemblies, wherein preferably, the end of the strut to be connected has a rectangular cross-sectional shape formed by a tubular element as described herein.

[0067] In this way, truss structures can be formed relatively easily and efficiently. It should be understood that different struts in at least one strut can be connected to the same or different struts in the column assembly, and the offshore support structure can include one or more struts that are not directly connected to any of the column assemblies. Such struts can, for example, be connected to another strut connected to the column assembly, and / or can be connected to a wind turbine receiving element that can be used in the same connecting structure where a portion of the truss structure can be formed.

[0068] Preferably, the connection between the end of the strut and the column assembly includes welding the straight plate edge of the end of the strut to and / or performing the welding of a straight plate edge formed on the column assembly, wherein preferably, the straight plate edge is formed as part of the corresponding connector structure of the strut and the column assembly. The straight plate edges to be connected are preferably arranged and / or shaped to be aligned with each other, particularly extending in the same plane and / or defining an intermediate gap for welding, wherein the gap width is in the range of 1 to 10 mm, preferably 2 to 7 mm, and more preferably 3 to 5 mm. To facilitate welding, the straight plate edges as described herein preferably extend horizontally or vertically during connection, wherein it should be understood that, in this context, a so-called vertical plate edge can still be considered inclined, i.e., in the sense that the corresponding plate extends vertically when viewed perpendicular to the surface of the plate while the edge extends at a slightly inclined angle.

[0069] In this way, the ends of the struts can be welded to the column assembly in a particularly effective and efficient manner.

[0070] Preferably, the end of the strut is cut to size before connection to the column assembly, for example, as mentioned elsewhere in the context of tubular elements. Although there may be possible variable conditions, such as temperature variations that could affect the precise length of the strut, this cutting to size can advantageously facilitate, for example, precise mating with the connector structure of the column assembly.

[0071] Preferably, the connection between the end of the strut and the column assembly involves manipulating the end of the strut to the appropriate position on the column assembly in a substantially downstream direction. In this way, the manipulation can be relatively well controlled, for example, using a crane.

[0072] Preferably, to provide operating space for this manipulation, one or more other interfaces between the weldable plate edges or column assembly and the strut are inclined, for example, as mentioned elsewhere herein. Specifically, the interface of the column assembly may be inclined partially upward, while the interface of the strut may be inclined partially downward, so as to allow the interfaces to approach each other when the strut is lowered relative to the column assembly.

[0073] Optionally, the end of the horizontal strut is connected to the column assembly directly above the end of the diagonal strut already connected to the column assembly. Advantageously, in this way, effective nodes of the truss structure can be formed at the joints of the column assemblies. Alternatively or additionally, the end of the horizontal strut may be connected to the column assembly at a distance from any diagonal strut connected to or to be connected to the same column assembly.

[0074] It should be understood that the various aspects and options described herein can be combined in different ways, such that options described in the context of a structure may be applied in the context of a method, and / or vice versa. Attached Figure Description

[0075] The invention will be further explained below using embodiments and accompanying drawings. The drawings are schematic and only show embodiments. In the drawings, corresponding reference numerals are provided for corresponding elements. For clarity, some reference numerals have been omitted in some of the drawings, wherein the presence of corresponding elements in those drawings can be understood, for example, from one or more other drawings, especially when considered in conjunction with this specific embodiment.

[0076] In the attached diagram:

[0077] Figure 1 A perspective view of a floating offshore support structure, on which a wind turbine is supported;

[0078] Figure 2 A transparent perspective view showing a section of tubular element having connected cylindrical tubular elements.

[0079] Figure 3 A transparent perspective view of the tubular element and illustrations of preferred weld joints at different longitudinal positions in the transverse cross-sectional view;

[0080] Figure 4 Display a plan view of the flat panel;

[0081] Figures 5A to 5E The display shows a structure formed by four plates. Figure 3 A perspective view of subsequent steps in the method for constructing tubular elements, each plate having Figure 4 The design shown in the image, in which Figure 5E The image also shows additional tubular cylindrical elements connected together;

[0082] Figure 6 show Figure 3 An axial view of a tubular element, i.e., a view in the longitudinal direction;

[0083] Figure 7 Display has Figure 5E An opaque perspective view of the tubular element connected to another tubular element;

[0084] Figure 8 Display has Figure 7 A view of the tubular element connected to another tubular element in one direction, which is transverse to the longitudinal direction of the tubular element from the circumferential position of the corner corresponding to the rectangular cross-sectional shape.

[0085] Figure 9 Show an isometric view of the deformable plate of the tubular element and auxiliary lines illustrating its geometry;

[0086] Figures 10A to 10CShowing a perspective view illustrating the steps in assembling the floating offshore support structure, especially the connection between the two struts and the column assembly;

[0087] Figure 11A and Figure 11B Showing a perspective view illustrating the steps in assembling the floating offshore support structure, especially the connection between the struts and the damping box;

[0088] Figure 12 Showing a transparent perspective view of a tubular element with a reinforced structure; and

[0089] Figure 13 Shows a cross-sectional side view of an offshore wind farm that includes a floating offshore support structure and wind turbines supported on the floating offshore support structure. Detailed Implementation

[0090] Figure 1 A floating offshore support structure 1 is shown, on which a wind turbine 2 is supported. The floating offshore support structure 1 includes three column assemblies 3, each comprising a semi-submersible column 4. The column assemblies 3 are interconnected by a truss structure 5, which includes struts 6 (particularly horizontal struts 6a and diagonal struts 6b) as truss members. WO2022 / 086329A1 discloses a floating offshore support structure having a similar integral configuration of semi-submersible columns interconnected by a truss structure, but does not include the various improvements provided in this disclosure.

[0091] Figure 13 Display includes Figure 1 The offshore wind farm 7 is of the type of floating offshore support structure 1 shown in the diagram, wherein the corresponding wind turbines 2 are supported on the floating offshore support structure. The floating offshore support structure 1 is preferably anchored to the seabed. Figure 13 As can be seen, column 4 of the floating offshore support structure 1 is semi-submersible to allow the wind turbine 2 to be floated and supported at sea level S. In column 4 and... Figure 1 The corresponding draft line D is indicated on other components in the system.

[0092] The struts 6 of the truss structure 5 are typically tubular, comprising cylindrical steel tubular elements 8 forming most of the length of the strut, as is typical for struts. In embodiments of this disclosure, advantageously, the strut 6 further comprises one or two steel tubular elements 9 as respective longitudinal end sections of the strut 6, the steel tubular elements providing a rectangular cross-sectional shape Tr for the strut 6 at the respective end, while matching the circular cross-sectional shape Tc of the cylindrical tubular element 8 at the connection point, wherein a smooth transition region Xt relative to the cross-sectional shape is formed therebetween.

[0093] An embodiment of the tubular element 9 providing such a transition is shown in Figure 1 , Figure 2 , Figure 3 , Figure 5E , Figure 6 , Figure 7 , Figure 8 , Figures 10A to 10C , Figure 11B and Figure 12 In particular, this type of tubular element 9 can be formed from four initial flat steel plates 10f, as will be specifically referred to below. Figure 4 and Figures 5A to 5E The explanation given.

[0094] To form the tubular element 9, four elongated flat steel plates 10f may be provided, each extending in the longitudinal direction L and having two opposing lateral edges 11. An embodiment of such plates 10f is shown in... Figure 4 and Figure 5A In the middle. Like with Figure 5A In comparison, for example, in Figure 5B As can be seen, each deformable element in plate 10f causes the cross-sectional shape of deformable plate 10d to smoothly transition between a straight shape Pr and an arcuate shape Pa along the longitudinal direction L. For example... Figures 5C to 5E As illustrated, a tubular element 9 can then be formed by interconnecting four deformable plates 10d along their lateral edges 11. As part of the tubular element 9, the interconnected deformable plates 10d are arranged such that each deformable plate 10d forms a corresponding circumferential segment of the tubular element 9, and the cross-sectional shape of the tubular element 9 smoothly transitions along the longitudinal direction L from a circular shape Tc (i.e., where the cross-sectional shape of the deformable plate 10d is an arc shape Pa) to a rectangular shape Tr (especially a square shape, i.e., where the cross-sectional shape of the deformable plate 10d is a straight shape Pr).

[0095] In the shown embodiment, each of the four deformable plates 10d extends beyond the end of the transition region Xp in the longitudinal direction L at the longitudinal side of the transition region Xp of the cross-sectional shape of the plate 10d, wherein the cross-sectional shape of the plate 10d is a straight shape Pr. The interconnected deformable plates 10d are arranged such that the tubular element 9 extends beyond the end of the transition region Xt in the longitudinal direction L at the longitudinal side of the transition region Xt of the cross-sectional shape of the tubular element 9, wherein the cross-sectional shape of the tubular element 9 is a rectangular shape Tr.

[0096] In the shown embodiments, as from Figure 8It can be best understood that the smooth transition zone Xt of the cross-sectional shape of the tubular element 9 matches the constant or smoothly varying cross-sectional shape of the tubular element 9 adjacent to the transition zone Xt on the longitudinal side where the cross-sectional shape of the tubular element 9 is a rectangular shape Tr, so as to provide continuous smoothness along the longitudinal direction L across the respective ends of the transition zone Xt, wherein the plates 10 are deformed and arranged to each other to provide this match.

[0097] In the illustrated embodiments, please refer again specifically to Figure 8 To provide this match, the plates 10 are deformed and arranged such that the plates 10d bulge outward along the transition region Xt at their interconnecting lateral edges 11, especially compared to the imaginary straight line that interconnects the circular shape Tc and the rectangular shape Tr at the positions corresponding to the respective lateral edges 11.

[0098] In the shown embodiment, on the side of the transition region Xt where the cross-sectional shape of the tubular element 9 is rectangular Tr, adjacent deformable plates in the interconnected deformable plates 10d extend at right angles to each other along the circumferential direction C of the tubular element 9, particularly conforming to the rectangular shape Tr. Figure 3 The corresponding illustration for fillet weld II is shown in the image, as further explained elsewhere in this document.

[0099] In the shown embodiment, on the side of the transition region Xt where the cross-sectional shape of the tubular element 9 is circular Tc, adjacent deformable plates in the interconnected deformable plates 10d extend at least at the lateral edge 11 of the interconnection at a flat angle to each other along the circumferential direction C of the tubular element 9, particularly conforming to the corresponding local tangent of the circular shape Tc at the lateral edge 11 of the interconnection. Figure 3 The corresponding diagram for butt welding IV is shown in the image, as further explained elsewhere in this document.

[0100] In the illustrated embodiment, along the transition region Xt, the angle between the plates 10d at the interconnecting lateral edges 11 gradually and monotonically changes between a right angle and a straight angle. Figure 3 The diagram shows the corresponding type of welding III, which is an intermediate type between fillet weld and butt weld, as further explained elsewhere in this document.

[0101] Special Reference Figure 4 and Figures 5A to 5B The longitudinal centerline M of plate 10 can remain undeformed due to deformation of plate 10. Alternatively, one or more deformations of the centerline M may exist, for example, at the ends of the transition zone Xt where the tubular element 9 has a rectangular cross-sectional shape Tr. In this way, for example, a change in the cross-sectional shape of the tubular element 9 outside the aforementioned transition zone Xt can be achieved, for example, to provide a different rectangular shape at the ends of the tubular element 9 compared to the ends at the ends of the transition zone Xt, as... Figures 10B to 10CThe situation is as described in the embodiment. In this embodiment, the diameter of the tubular element 9 of the horizontal strut 6a is 2 meters, with a circular cross-sectional shape to match the diameter of the other cylindrical tubular element 8. However, at the end of the tubular element 9 forming the connector structure 17 for connection with the column assembly 3, the tubular element 9 has a lateral width of 2 meters and a lateral height of 2.5 meters, i.e., a non-square rectangular cross-sectional shape, to match the corresponding dimensions of the corresponding connector structure 18 of the column assembly 3. Additionally, as... Figure 10C As indicated herein, in detail D of the longitudinal section view, curvature may be formed in one or more of the deformable plates 10d, thereby providing a smooth transition zone along the longitudinal direction between this horizontal section of plate 10d extending toward the connection with column assembly 3 and this inclined section of plate 10d extending toward the additional cylindrical tubular element 8. Such curvature may, for example, be arranged at a distance from the transition zone Xt. It should be understood that the sections referred to herein as horizontal or inclined may be oriented differently depending on other design choices and / or circumstances, for example, where such an arrangement is applied to diagonal struts rather than horizontal struts.

[0102] In the illustrated embodiments, particular reference is made to Figure 4 and Figures 5A to 5B For each of the plates 10, a triangular segment 12 of the plate 10 remains undeformed by deformation of the plate 10. The triangular segment 12 is defined by a triangular base and a triangular apex, where the triangular base corresponds to the straight cross-sectional shape Pr of the plate 10d on the side of the transition zone Xp where the cross-sectional shape Tr of the tubular element 9 is rectangular, and the triangular apex corresponds to the intersection of the longitudinal centerline M and the arcuate cross-sectional shape Pa of the plate 10d on the side of the transition zone Xp where the cross-sectional shape Tc of the tubular element 9 is circular. Along the transition zone Xp, the triangular segment 12 is the only segment of the plate 10d that remains undeformed by deformation of the plate 10 before the interconnection of the deformed plates 10d. Again, as explained above, further deformation of the plate 10 may exist outside the transition zone Xp.

[0103] Special Reference Figure 6 When viewed in the longitudinal direction L, the circular cross-sectional shape Tc does not extend beyond the rectangular cross-sectional shape Tr. Here, the side surface of the rectangular cross-sectional shape Tr corresponds to the corresponding tangent of the circular cross-sectional shape Tc. Alternatively, when viewed in the longitudinal direction, the side surface of the rectangular cross-sectional shape may be spaced apart from the circular cross-sectional shape.

[0104] Special Reference Figure 3 Here, four deformable plates 10d are interconnected along their lateral edges 11, including at least along the transition region Xt and preferably along the entire length of two lateral edges 11 together, welding adjacent lateral edges 11 of adjacent deformable plates 10d together. (See from...) Figure 3 As can be understood from the icons I to IV at different positions along the longitudinal direction L of the tubular element 9, when the cross-sectional shape of the tubular element 9 is circular (Tc), the edges of the plate 10d are preferably welded together by butt joint IV. When the cross-sectional shape of the tubular element 9 is rectangular (Tr), the plate 10d is preferably welded together by corner joint II. Correspondingly, at the middle position along the transition zone Xt, an intermediate type of weld joint III can be applied. At the end of the tubular element 9, a T-joint I can be applied. Although not explicitly shown, it should be understood that another intermediate type of weld joint can be applied between the T-joint I and the corner joint II. It should also be understood that, for clarity of the drawings, Figure 3 The illustrations I through IV show each of the plate edges as a straight line, although the plate can actually be curved at its edges, as described herein.

[0105] Special Reference Figure 12 The method may further include the interior of the tubular element 9, particularly at locations where the cross-sectional shape of the tubular element 9 is rectangular (Tr), by attaching one or more reinforcing structures 13 to the tubular element 9.

[0106] In the shown embodiment, the deformation of plate 10 is limited in that the deformable plate 10d, which serves as a surface, is a deployable or single-bendable surface; the deformable plate 10d does not contain any joints; so as to exclude any radius of the deformable plate 10d that would have a local thickness less than ten times that of the plate 10d; and so as to prevent any deformation of plate 10 that results in a local elongation of more than 5% of the steel plate material comprising plate 10.

[0107] In the illustrated embodiment: the tubular element 9 is formed without any joints relative to the longitudinal direction L; and the deformable sections of the plate 10d are shaped according to corresponding conical surfaces 14, each conical surface defining an imaginary inclined cone having a vertex 15 located outside the longitudinal and / or lateral ranges of the transition zone Xt and / or the plate 10d, wherein preferably, the base 16 of the imaginary inclined cone corresponds to the end of the transition zone Xt having a circular cross-sectional shape Tc. Such vertices 15 and bases 16 have been... Figure 9 As an example, the surface of the deformable plate 10d is shaded to better distinguish plate 10d from the surrounding surface. Figure 9 Various auxiliary lines in the diagram. Based on... Figure 9 The auxiliary lines in the diagram suggest that, given the relatively distant vertex 15, the radius of curvature of the deformable plate 10d can be relatively large throughout the plate 10d, especially near the end of the transition region Xp, where the cross-sectional shape is a straight line shape Pr. In contrast, known tubular elements tend to have excessively small radii in such regions.

[0108] exist Figure 3 , Figure 4, Figures 5A to 5E , Figure 6 , Figure 7 and Figure 8 In order to illustrate the shape of the conical surface 14, lines have been drawn across those surfaces; that is, lines following the curvature of the surface in the corresponding transverse plane, and lines following the trajectory of straight lines across the surface. The lines following the trajectory of straight lines intersect with the lines following the curvature, thus forming a grid. Figure 4 and Figure 5A In these figures, lines following the curvature have been omitted because these figures show plate 10f in its flat state before deformation. It is evident that lines following a straight trajectory extend from the lateral edge 11 of plate 10 to the end of plate 10, which has an arcuate cross-sectional shape Pa after deformation. It should be understood that, according to... Figure 8 The view, following the lines of curvature in Figure 8 It is displayed as a vertical line.

[0109] As mentioned above, in the shown embodiment, the strut 6 further includes an additional cylindrical tubular element 8 as another longitudinal section of the strut 6, which is connected to the tubular element 9 at the side of the transition region Xt where the cross-sectional shape of the tubular element 9 is circular Tc. In the shown embodiment, the circular cross-sectional shape of the additional cylindrical tubular element 8 matches the circular cross-sectional shape Tc of the tubular element 9.

[0110] In the illustrated embodiment, on one side of the transition zone where the tubular element 9 has a rectangular cross-sectional shape Tr, the tubular element 9 forms a connector structure 17 for connecting the strut 6 to the column assembly 3, particularly to its connector structure 18, as another part of the floating offshore support structure 1, especially at the longitudinal end of the strut 6. Such connector structures 17, 18 and connections are shown, for example, in… Figures 10A to 10C and Figures 11A to 11B In the middle. Here, it can be seen that at the connection with the column assembly 3, the strut 6 has a rectangular cross-sectional shape formed by the tubular element 9, thereby facilitating welding. A suitable corresponding connector structure 18 can be seen on the column assembly 3. The connector structure 17 of the strut 6 and the connector structure 18 of the column assembly 3 are specifically presented here as straight plate edges 19, 20 that can be welded together to form a connection.

[0111] like Figures 10A to 10C and Figure 11A and Figure 11B As can be seen, one or more interfaces between the column assembly 3 and the strut 6a, particularly the vertical extender 20 in the edge of the straight plate, may be inclined, in particular to provide maneuvering space for maneuvering the end of the strut 6 to a substantially downstream position for assembling the floating offshore support structure 1.

[0112] Furthermore, it can be seen that the column assembly 3 and the strut 6 are configured here to help stabilize the strut 6 relative to the column assembly 3 before and / or during the formation of the connection between the column assembly 3 and the strut 6, in particular by allowing the strut 6 to be at least partially supported on the column assembly 3, for example by using the connector structure 17 of the strut 6 to partially overlap the connector structure 18 of the column assembly 3.

[0113] Special Reference Figure 1 At the connection between column assembly 3 and strut 6, column 4 has a polygonal, particularly hexagonal, cross-sectional shape with rounded vertices, wherein most of strut 6 connects to column assembly 3 at the circumferential positions corresponding to the vertices of the polygonal shape of column 4. Meanwhile, in Figure 1 In this embodiment, three of the struts 6 are connected to the column assembly 3 at different circumferential positions, particularly at the circumferential positions corresponding to one side of the polygonal shape of the column 4. Specifically, in this embodiment, the corresponding column assembly 3 is arranged opposite the side of the floating offshore support structure 1 with the wind turbine receiving element 25, i.e., facing... Figure 1 The upper right corner of the attached image.

[0114] Figure 1 It can also be seen that each column assembly 3 includes a damping box 21 at its lower end. See also [reference needed] for a portion of this damping box 21. Figures 11A to 11B In these embodiments, the damping box 21 has a top plate 22 and a bottom plate 23 spaced apart from the top plate 22, wherein the top plate 22 and the bottom plate 23 are interconnected by one or more side plates 24, wherein a strut 6a is connected to the damping box 21 at one or more side plates 24, particularly where the exterior of the damping box 21 does not overlap with either the top plate 22 or the bottom plate 23. At the connection with the damping box 21, the strut 6a here has a rectangular cross-sectional shape, particularly formed by a tubular element 9 on one side of the transition zone Xt where the cross-sectional shape of the tubular element 9 is rectangular Tr. One straight side of the cross-sectional shape of the strut 9 (particularly corresponding to the horizontal plate edge 19) is aligned with the top plate 22 of the damping box 21, wherein the opposite straight side of the cross-sectional shape of the strut 9 (particularly corresponding to the other horizontal plate edge 19) is aligned with the bottom plate 23 of the damping box 21. Figure 1 As can be seen, as another possibility, the diagonal strut 6b can be connected to the column assembly 3 at the corner of the top plate 22 of the damping box and one side of the column 4.

[0115] Floating offshore support structure 1, such as Figure 1 The embodiments shown herein can be assembled using a method comprising: providing three column assemblies 3, each column assembly comprising a corresponding semi-submersible column 4; providing a plurality of struts 6 as described herein; and interconnecting the column assemblies 3 by means of a truss structure 5, the truss structure 5 comprising struts 6, particularly as corresponding truss members, including horizontal struts 6a and diagonal struts 6b herein.

[0116] Here, the interconnection of the column assemblies 3 includes connecting the ends of the struts 6 to one of the column assemblies 3. Before or after connecting this end, the opposite ends of the same strut 6 may be connected to another column assembly 3, or to another strut 6, or to the wind turbine receiving element 25. The wind turbine receiving element 25 is preferably positioned between the two in the column assemblies 3. The element to which a particular strut 6 is to be connected typically depends on the design of the particular strut and its position in the design of the truss structure 5, as can be seen from... Figure 1 The embodiments shown herein are for understanding purposes only.

[0117] Here, the connection between the end of the strut 6 and the column assembly 3 is performed by welding the straight plate edges 19, 20 of the end of the strut 6 to the straight plate edges 19, 20 formed on the column assembly 3, wherein the straight plate edges 19, 20 form part of the corresponding connector structures 17, 18 of the strut 6 and the column assembly 3. As part of forming the truss structure 5, the aforementioned connection of the other end of such a strut 6 may or may not involve such welding of the straight plate edges. As explained elsewhere herein, the straight plate edges are preferably horizontal plate edges 19 and vertical plate edges 20, wherein specifically, the vertical plate edge 20 may be tilted to facilitate manipulation during assembly. Alternatively, conventional methods of connecting the ends of struts to form a truss structure may be used for some ends of some struts.

[0118] As needed, the end of the strut 6, particularly the corresponding connector structure 17, can be cut to size before being connected to the column assembly 3. This cutting effectively induces the repositioning of the corresponding straight plate edge by severing the original plate edge to form a new plate edge at the cut. To facilitate this, the strut 6, particularly the connector structure 17, can initially be constructed to be oversized, thereby allowing the dimensions of the strut 6 to be precisely sized shortly before being connected to the column assembly 3.

[0119] Special Reference Figure 10B and Figure 10C The end of the strut 6a is connected to the column assembly 3, which includes manipulating the end of the strut 6a to the appropriate position on the column assembly 3 in the basic downstream direction. Figure 10B The middle is indicated by a dashed arrow.

[0120] As mentioned elsewhere in this document, to provide operating space for this operation, the mutually weldable plate edges 20, which serve as the interface between the column assembly 3 and the strut 6a, are inclined here. Figure 11A and Figure 11B A similar configuration using inclined edges can be seen in the diagram, which is used for the connection between the horizontal strut 6a and the damping box 21. Although not shown, it should be understood that a similar configuration using inclined edges can be applied relative to the diagonal strut 6b.

[0121] Further in Figure 10B and Figure 10C As can be seen, the end of the horizontal strut 6a connects to the column assembly 3 directly above the end of the diagonal strut 6b, which is already connected to the column assembly 3, particularly at the top of the column assembly 3. Specifically, as shown, the horizontal strut 6a and the diagonal strut 6b can therefore butt-joint with each other and / or join at their connection with the column assembly 3, wherein at the butt-joint and / or joint, the struts 6a and 6b can even be welded together, particularly by welding the butt-joint and / or adjacent straight plate edges. Figure 10A and Figure 10B As shown, an intermediate connecting plate 26 may be provided, which can form a common portion of the two struts 6a and 6b. Such a connecting plate may, for example, extend primarily horizontally and may form a horizontal plate edge 19 that can be shared by the connector structure 17 of both struts 6a and 6b. The connecting plate 26 may, for example, initially form a portion of the diagonal strut 6b, wherein the horizontal strut 6a can be connected to the connecting plate 26 (see [link to diagram]). Figures 10B to 10C This allows plate 26 to then form portions of struts 6a and 6b.

[0122] although Figures 10A to 10C The horizontal strut 6 and the diagonal strut 6b are shown to be closely connected to the top of the same column assembly 3, but it should be understood that, for example, they are combined... Figure 1 The connection between the horizontal strut 6a and the top of the column assembly 3 does not always need to be close to the connection between the diagonal strut 6b and the same column assembly 3. Specifically, in Figure 1 In this embodiment, the five ends of the horizontal strut 6a are connected to the top of the column assembly 3, while no diagonal struts are connected directly below. Therefore, in such cases, this can be omitted. Figure 10A The lower connector structure in connector structure 18 shown, and / or similar structures can be applied. Figure 11A The connector structure 18 shown in the diagram, for example, uses a design similar to... Figure 11B The design of the strut 6a in the embodiment shown is also shown in Figure 2 In China. Further integration Figure 1 It should be understood that some struts 6a and / or 6b may be connected to column assembly 3 at a location corresponding to the preferred polygonal cross-sectional shape of column 4, rather than at the vertex.

[0123] Although embodiments and accompanying drawings have been used to explain the invention herein, they are not intended to limit the scope of the invention as defined by the claims. Within this scope, those skilled in the art, possessing the benefit of this disclosure, will understand that many variations, combinations, and extensions are possible. For example, struts may be arranged differently in the truss structure than in the shown embodiments, for instance, with different numbers and / or positions of horizontal and / or diagonal struts, and some of these struts may not contain any rectangular cross-sectional shape. Deformable plates need not be connected along their entire lateral edge, for example, where the lateral edge of one plate extends longitudinally beyond the lateral edge of the adjacent plate, as in, for example… Figure 10B The horizontal strut 6a in the middle is connected to the other strut 6a. Figure 10C The case prior to diagonal strut 6b in the previous version. All such variations are included within the scope of the invention as defined by the appended claims.

[0124] Although the invention has been described herein with reference to embodiments and accompanying drawings, these are not intended to limit the scope of protection of the invention as defined by the claims. Within this scope, those skilled in the art can make various modifications, combinations, and extensions based on the disclosure of this invention. For example, the arrangement of struts in the truss structure may differ from the illustrated embodiments, for example, the number and / or position of horizontal and / or diagonal struts may differ, and some struts may not have a rectangular cross-sectional shape. Deformable plates do not necessarily have to be connected along their entire lateral edge, for example, where the lateral edge of one plate extends longitudinally beyond the lateral edge of the adjacent plate, as in, for example... Figure 10B The horizontal strut 6a in its connection Figure 10C The case prior to diagonal strut 6b in the previous version. All such variations are included within the scope of protection of the invention as defined in the appended claims.

[0125] [List of Labels in the Attached Image] 1. Floating offshore support structure 2. Wind turbine 3. Column assembly 4. Semi-submersible column 5. Truss structure 6. Support struts (including 6a and 6b) 6a. Horizontal strut 6b. Diagonal strut 7. Offshore wind farms 8. Cylindrical tubular elements 9. Tubular elements that provide a transition between circular and rectangular cross-sectional shapes. 10. Slender steel plates for tubular components (including: 10d, 10f) 10d. Deformable plate 10f. Flat plate 11. Lateral edges of the board 12. The triangular section of the board 13. Reinforce the structure 14. Conical surface 15. The vertex of an imaginary tilted cone 16. The base of an imaginary tilted cone 17. Connector structure of the strut 18. Column assembly connector structure 19. The horizontal straight edge of the connector structure. 20. Vertical straight plate edge of connector structure 21. Damping box 22. Top plate of the damping box 23. The base plate of the damping box 24. Side plate of the damping box 25. Wind turbine receiving components 26. Connecting plate between horizontal struts and diagonal struts C. Circumferential direction of tubular elements and struts D. Draft line L. Longitudinal direction M. Longitudinal centerline of the plate Pa. The arcuate cross-sectional shape of the deformed plate Pr. The straight cross-sectional shape of the plate Tc. Circular cross-sectional shape of tubular elements Tr. Rectangular cross-sectional shape of tubular elements S. Sea level Xp. Transition zone of the plate's cross-sectional shape Xt. Transition zone of cross-sectional shape of tubular element I. T-connector II. Fillet weld III. Intermediate type connector IV. Butt joint.

Claims

1. A method of forming a tubular element, said tubular element serving as a longitudinal section of a strut in a truss structure for a floating offshore support structure for a wind turbine, said method comprising: Four elongated flat steel plates are provided, each of the four elongated flat steel plates extending in a longitudinal direction and having two opposite lateral edges; For each of the plates, the plate is deformed such that the cross-sectional shape of the plate smoothly transitions between a straight shape and an arcuate shape along the longitudinal direction; and The tubular element is formed by interconnecting four deformed plates along their lateral edges. As part of the tubular element, the interconnected deformed plates are arranged such that each deformed plate forms a corresponding circumferential segment of the tubular element, and the cross-sectional shape of the tubular element smoothly transitions from a circular shape to a rectangular shape along the longitudinal direction; that is, in the circular shape, the cross-sectional shape of the deformed plate is an arc shape; and in the rectangular shape, the cross-sectional shape of the deformed plate is a straight shape.

2. The method of claim 1, wherein each of the four deformed plates extends beyond the end of the transition zone in the longitudinal direction at the longitudinal side of the plate where the cross-sectional shape of the plate is a straight shape. The interconnected deformed plates are arranged such that the tubular element extends beyond the end of the transition zone in the longitudinal direction at the longitudinal side of the cross-sectional shape of the tubular element, where the cross-sectional shape of the tubular element is rectangular.

3. The method of claim 2, wherein a smooth transition zone of the cross-sectional shape of the tubular element at the longitudinal side of the transition zone where the cross-sectional shape of the tubular element is rectangular matches a constant or smoothly varying cross-sectional shape of the tubular element adjacent to the transition zone, so as to provide continuous smoothness across the respective ends of the transition zone in the longitudinal direction, wherein the plates are deformed and arranged to each other to provide the matching.

4. The method of claim 3, wherein, To provide the matching, the plates are deformed and arranged such that the plates bulge outward along the transition zone at their interconnecting lateral edges, especially compared to an imaginary straight line that interconnects the circular shape and the rectangular shape at positions corresponding to the respective lateral edges.

5. The method as described in any one of the preceding claims, wherein, In the transition zone, on the side where the cross-sectional shape of the tubular element is rectangular, adjacent plates of the interconnected deformed plates extend at right angles to each other along the circumferential direction of the tubular element, particularly conforming to the rectangular shape. In the transition zone, on the side where the cross-sectional shape of the tubular element is circular, adjacent plates of the interconnected deformed plates extend at a flat angle to each other along the circumferential direction of the tubular element at least at the lateral edge of the interconnection, particularly conforming to the corresponding local tangent of the circular shape at the lateral edge of the interconnection.

6. The method of claim 5, wherein, Along the transition zone, the angle between the plates at the lateral edges of the interconnection gradually and monotonically changes between the right angle and the flat angle.

7. The method of any of the preceding claims, wherein the longitudinal centerline of the plate remains undeformed by the deformation of the plate.

8. The method of claim 7, wherein, For each of the plates, the triangular segment of the plate remains undeformed by the deformation of the plate, the triangular segment being defined by a triangular base and a triangular apex. The triangular base corresponds to the straight cross-sectional shape of the side of the tubular element in the transition zone where the cross-sectional shape is rectangular. The apex of the triangle corresponds to the intersection of the longitudinal centerline and the arcuate cross-sectional shape of the plate in the transition zone, where the cross-sectional shape of the tubular element is circular.

9. The method of claim 8, wherein, Along the transition region, the triangular segment is the only segment of the plate that remains undeformed by the deformation of the plate before the interconnection of the deformed plate.

10. The method as described in any of the preceding claims, wherein, When viewed in the longitudinal direction, the circular cross-sectional shape does not extend beyond the rectangular cross-sectional shape, wherein preferably, the side of the rectangular cross-sectional shape corresponds to the corresponding tangent of the circular cross-sectional shape.

11. The method of any of the preceding claims, wherein interconnecting the four deformed plates along their lateral edges comprises at least welding adjacent lateral edges of adjacent plates of the deformed plates together along the transition region.

12. The method as claimed in any of the preceding claims, further comprising attaching one or more reinforcing structures to the tubular element, particularly at locations where the cross-sectional shape of the tubular element is rectangular.

13. The method as described in any of the preceding claims, wherein the deformation of the plate is limited: The plate, which is deformable as a surface, is a deployable or single-bendable surface; and / or The deformed plate contains no joints; In order to eliminate deformation, the plate will have any radius less than ten times the local thickness of the plate; and / or In order to prevent the plate from undergoing any deformation with a local elongation greater than 5% in the steel plate material containing the plate.

14. The method as described in any of the preceding claims, wherein: The tubular element is formed without any joints relative to the longitudinal direction; and / or The deformable sections of the plate are shaped according to the corresponding conical surfaces of the respective defined imaginary tilted cones, which have apexes located outside the longitudinal and / or lateral ranges of the transition zone and / or the plate, wherein preferably, the base of the imaginary tilted cone corresponds to the end of the transition zone having the circular cross-sectional shape.

15. A tubular element formed by the method as described in any of the preceding claims, the tubular element serving as a longitudinal section of a strut for a truss structure for a floating offshore support structure for a wind turbine.

16. A strut for a truss structure of a floating offshore support structure for a wind turbine, the strut comprising a tubular element as a longitudinal section of the strut, preferably the tubular element as claimed in claim 15, wherein... The cross-sectional shape of the tubular element transitions from a circular shape to a rectangular shape along the longitudinal direction of the tubular element.

17. The strut of claim 16, wherein the tubular element, particularly on the side of the transition region where the cross-sectional shape of the tubular element is rectangular, forms a connector structure for connecting the strut to another part of the floating offshore support structure, particularly at the longitudinal end of the strut.

18. The strut as claimed in claim 16 or 17, further comprising an additional cylindrical tubular element as another longitudinal section of the strut, the additional cylindrical tubular element being connected to the tubular element at the side of the transition region where the cross-sectional shape of the tubular element is circular. Preferably, the circular cross-sectional shape of the other cylindrical tubular element matches the circular cross-sectional shape of the tubular element.

19. A floating offshore support structure for a wind turbine, comprising struts as claimed in any one of claims 16 to 18, wherein the struts form truss members as part of a truss structure of the floating offshore support structure, the truss structure interconnecting two, three or more column assemblies of the floating offshore support structure, each column assembly comprising a corresponding semi-submersible column, wherein the struts are connected, particularly at their ends, to at least one of the column assemblies.

20. The floating offshore support structure as described in claim 19, wherein, At the connection with the column assembly, the strut has a rectangular cross-sectional shape, particularly formed by the tubular element in the transition zone on the side where the tubular element has a rectangular cross-sectional shape.

21. The floating offshore support structure of claim 19 or 20, wherein one or more interfaces between the column assembly and the strut are inclined, in particular to provide maneuvering space for maneuvering the end of the strut into place in a substantially downstream direction for assembling the floating offshore support structure.

22. The floating offshore support structure of any one of claims 19 to 21, wherein the column assembly and the strut are configured to help stabilize the strut relative to the column assembly before and / or during the formation of a connection between the column assembly and the strut, particularly by allowing the strut to be at least partially supported on the column assembly.

23. The floating offshore support structure as described in any one of claims 19 to 22, wherein, At the connection between the column assembly and the strut, the column has a polygonal, preferably hexagonal, cross-sectional shape, possibly with circular vertices, wherein the strut is connected to the column assembly at a circumferential position corresponding to the vertex of the polygonal shape of the column.

24. The floating offshore support structure as claimed in any one of claims 19 to 23, comprising a damping box, particularly as part of the column assembly mentioned in any one of claims 19 to 23.

25. The floating offshore support structure of claim 24, wherein the damping box has a top plate and a bottom plate spaced apart from the top plate, wherein the top plate and the bottom plate are interconnected by one or more side plates, wherein the struts are connected to the damping box at the one or more side plates, particularly provided that the exterior of the damping box does not overlap with either the top plate or the bottom plate.

26. The floating offshore support structure as described in claim 24 or 25, wherein, At the connection with the damping box, the strut has a rectangular cross-sectional shape, particularly formed by the tubular element in the transition zone on the side where the cross-sectional shape of the tubular element is rectangular.

27. The floating offshore support structure of claim 26, which is dependent on claim 25, wherein a straight side of the cross-sectional shape of the strut is aligned or at least parallel to one of the top plate and the bottom plate of the damping box, wherein preferably, the opposite straight side of the cross-sectional shape of the strut is aligned or at least parallel to the other of the top plate and the bottom plate of the damping box.

28. A wind turbine comprising a floating offshore support structure as claimed in any one of claims 17 to 27, wherein the wind turbine is supported on the floating offshore support structure, particularly on the truss structure and / or spaced apart from any semi-submersible columns of the floating offshore support structure.

29. An offshore wind farm comprising at least one wind turbine as described in claim 28.

30. The offshore wind farm of claim 29, wherein the floating offshore support structure buoyantly supports the wind turbine.

31. A method for assembling a floating offshore support structure as described in any one of claims 17 to 27, the method comprising: Provide at least two, preferably three, column assemblies, each column assembly comprising a corresponding semi-submersible column; Provide at least one strut as described in any one of claims 14 to 16; The at least two column assemblies are interconnected by a truss structure, which includes the at least one strut, particularly as a corresponding at least one truss member.

32. The method of claim 31, wherein the interconnection of the at least two column assemblies comprises connecting the end of one of the at least one strut to one of the column assemblies.

33. The method of claim 32, wherein the connection between the end of the strut and the column assembly comprises, and preferably is performed by, welding a straight plate edge of the end of the strut to a straight plate edge formed on the column assembly, wherein preferably, the straight plate edge is formed as part of a respective connector structure of the strut and the column assembly.

34. The method of claim 32 or 33, wherein the end of the strut is cut to size prior to its connection with the column assembly.

35. The method of any one of claims 32 to 34, wherein the connection of the end of the strut to the column assembly comprises manipulating the end of the strut to a suitable position at the column assembly in a substantially downstream direction. in, To provide maneuvering space for the aforementioned manipulation, preferably the weldable plate edges or one or more other interfaces between the column assembly and the strut are inclined.

36. The method of any one of claims 32 to 35, wherein the end of the horizontal strut is connected to the column assembly directly above the end of the diagonal strut already connected to the column assembly.

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