Floating structure

Abstract

Provided is a floating structure with which it is possible to increase rigidity and ensure the required strength with less steel material weight than conventional examples. A floating structure 1 according to a first embodiment is provided with: a lower structure 2 formed by a triangular frame; a main column 3 that is disposed at any one vertex section (first vertex section 2a) of the lower structure 2; a linking member 4 that links the main column 3 and remaining vertex sections (second vertex section 2b and third vertex section 2c) of the lower structure 2 and where the main column 3 is not disposed; and sub-columns 5 that are disposed at the vertex sections (second vertex section 2b and third vertex section 2c) where the main column 3 is not disposed.

Description

Floating structure

[0001] The present invention relates to a floating structure, and more particularly to a semi-submersible floating structure.

[0002] For example, floating structures used in floating offshore wind power generation and the like are classified into semi-submersible type, spar type, and TLP (tension leg platform) type. A semi-submersible floating structure has a structure in which a semi-submersible floating platform is fixed to the seabed with mooring cables.

[0003] For example, FIG. 1 of Patent Document 1 discloses a floating structure composed of three columns and a plurality of upper and lower supports connecting these columns. FIGS. 2 to 9 of the same document disclose a floating structure composed of three columns, three pontoon members connecting these columns, and connectors.

[0004] Japanese Patent Publication No. 2024-529652

[0005] Semi-submersible floating structures have problems such as being likely to be enlarged and weighted to obtain sufficient buoyancy and restoring force for maintaining stability, and the structure being likely to become complicated due to many welded columns. These problems will become more prominent as the windmill is enlarged. Furthermore, as the windmill is enlarged, it is also necessary to increase the rigidity of the floating structure in order to avoid resonance with the natural vibration frequency of the windmill.

[0006] The present invention was conceived in view of such problems, and an object thereof is to provide a floating structure that can increase rigidity and ensure required strength with less steel weight than before.

[0007] According to the present invention, there is provided a floating structure including a lower structure body composed of a triangular frame body, a main column disposed at any one vertex portion of the lower structure body, and a connecting member connecting the remaining vertex portions of the lower structure body where the main column is not disposed and the main column, and including a three-dimensional truss structure composed of the lower structure body, the main column, and the connecting member.

[0008] The floating structure may include sub-columns positioned at the apex of the substructure where the main column is not located.

[0009] The floating structure may further include sub-columns positioned via support members connected to the apex portion of the substructure where the main column is not located.

[0010] The floating structure may have a polygonal pyramidal shape with the main column as its vertical axis.

[0011] Furthermore, the present invention provides a floating structure that includes a substructure composed of two triangular frames sharing one side, a main column positioned at one of the vertices located at both ends of the shared side, and a connecting member connecting the remaining vertices of the substructure where the main column is not located to the main column, and the substructure, the main column, and the connecting member constitute a three-dimensional truss structure.

[0012] The floating structure may include sub-columns positioned at the apex where the main column is not located.

[0013] The floating structure may include subcolumns positioned at the remaining vertices of the substructure that do not include the shared side.

[0014] The floating structure may further include subcolumns positioned via support members connected to the vertices of the shared side of the substructure where the main column is not located.

[0015] According to the floating structure of the present invention described above, it is possible to form a floating structure based on a three-dimensional truss structure, thereby increasing the rigidity of the floating structure and ensuring the required strength with less steel weight than in conventional methods.

[0016] This is a perspective view showing the usage state of the floating structure according to the first embodiment. This is an explanatory diagram of the floating structure shown in Figure 1, where (A) is a plan view, (B) is a side view seen from direction B in Figure 1(A), and (C) is a side view seen from direction C in Figure 1(A). This is a perspective view showing the usage state of the floating structure according to the second embodiment. This is an explanatory diagram of the floating structure shown in Figure 3, where (A) is a plan view, (B) is a side view seen from direction B in Figure 3(A), and (C) is a side view seen from direction C in Figure 3(A). This is a perspective view showing the usage state of the floating structure according to the third embodiment. This is an explanatory diagram of the floating structure shown in Figure 5, where (A) is a plan view, (B) is a side view seen from direction B in Figure 5(A), and (C) is a side view seen from direction C in Figure 5(A).

[0017] Embodiments of the present invention will be described below with reference to Figures 1 to 6. Here, Figure 1 is a perspective view showing the floating structure in use according to the first embodiment. Figure 2 is an explanatory diagram of the floating structure shown in Figure 1, where (A) is a plan view, (B) is a side view seen from direction B in Figure 1(A), and (C) is a side view seen from direction C in Figure 1(A). Note that in each of the figures in Figure 2, the superstructure (wind turbine) has been omitted for the sake of explanation.

[0018] The floating structure 1 according to the first embodiment, as shown in Figures 1 to 2(C), comprises a substructure 2 composed of a triangular frame, a main column 3 positioned at one of the vertices of the substructure 2 (first vertex 2a), connecting members 4 that connect the main column 3 to the remaining vertices of the substructure 2 where the main column 3 is not positioned (second vertex 2b and third vertex 2c), and subcolumns 5 positioned at the vertices where the main column 3 is not positioned (second vertex 2b and third vertex 2c). In this specification, "vertex" includes the point where angled lines intersect and the surrounding area (for example, the area enclosed by the dashed line in Figure 2(A)).

[0019] The floating structure 1 shown in Figure 1 has a wind turbine 6 installed on top of a main column 3. Note that the wind turbine 6 is just one example of a superstructure installed on top of the main column 3, and is not limited to this. Also, the dotted line shown on the floating structure 1 in Figure 1 represents the waterline of the floating structure 1.

[0020] The lower structure 2 is composed of a frame having an overall triangular shape, as shown in Figure 2(A), for example. Here, the sub-column 5 located at the second vertex 2b will be referred to as the first sub-column 51, and the sub-column 5 located at the third vertex 2c will be referred to as the second sub-column 52.

[0021] The lower structure 2 comprises a first frame 21 positioned between the main column 3 and the first sub-column 51, a second frame 22 positioned between the main column 3 and the second sub-column 52, and a third frame 23 positioned between the first sub-column 51 and the second sub-column.

[0022] The first frame 21 and the second frame 22 may be directly connected, or they may be connected via the main column 3. The first frame 21 and the third frame 23 may be directly connected, or they may be connected via the first sub-column 51. The second frame 22 and the third frame 23 may be directly connected, or they may be connected via the second sub-column 52.

[0023] The first frame 21, the second frame 22, and the third frame 23 may be made of plate material, or they may be cylindrical in shape with a cavity inside. Ballast tanks may also be placed inside the first frame 21, the second frame 22, and the third frame 23.

[0024] The main column 3 is a cylindrical support column on which a superstructure such as a wind turbine 6 is positioned. As shown in Figure 1, when the floating structure 1 is in use, the upper end of the main column 3 is located above the waterline, and the lower end of the main column 3 is located below the waterline.

[0025] A ballast tank (not shown) may be located inside the main column 3. Additionally, a protrusion (not shown) for connecting a mooring rope (not shown) may be located at the bottom of the main column 3.

[0026] The sub-columns 5 (first sub-column 51 and second sub-column) are cylindrical supports that provide buoyancy to the lower structure 2. As shown in Figure 1, when the floating structure 1 is in use, the upper ends of the sub-columns 5 (first sub-column 51 and second sub-column) are located above the waterline, and the lower ends of the sub-columns 5 (first sub-column 51 and second sub-column) are located below the waterline.

[0027] A ballast tank (not shown) may be placed inside the sub-column 5 (first sub-column 51 and second sub-column). Additionally, a protrusion (not shown) for connecting a mooring rope (not shown) may be placed at the lower part of the sub-column 5 (first sub-column 51 and second sub-column).

[0028] The connecting member 4 is a diagonal member that connects the lower structure 2 and the main column 3. The connecting member 4 comprises a first connecting member 41, one end of which is connected to the upper part of the main column 3 and the other end of which is connected to a position close to the first sub-column 51 of the first frame 21 (i.e., within the range of the second vertex 2b), and a second connecting member 42, one end of which is connected to the upper part of the main column 3 and the other end of which is connected to a position close to the second sub-column 52 of the second frame 22 (i.e., within the range of the third vertex 2c).

[0029] The floating structure 1 according to the first embodiment is composed of a three-dimensional truss structure consisting of a substructure 2 (first frame 21, second frame 22, and third frame 23), a main column 3, and connecting members 4 (first connecting member 41 and second connecting member 42). By using a three-dimensional truss structure as the foundation in this way, the rigidity of the floating structure 1 can be increased, and the required strength can be secured with less steel weight than in conventional structures.

[0030] Therefore, according to the floating structure 1 of this embodiment, even when the wind turbine 6, which is the superstructure, is enlarged, the strength of the floating structure 1 can be easily increased, and resonance with the natural frequencies of the wind turbine 6 and its blades can be easily avoided.

[0031] The floating structure 1 according to the first embodiment described above has a triangular pyramidal three-dimensional truss structure with the main column 3 as the vertical axis, but is not limited to this configuration. For example, although not shown, the floating structure 1 may have a square pyramidal three-dimensional truss structure with the main column 3 as the vertical axis. In other words, the floating structure 1 only needs to have a polygonal pyramidal three-dimensional truss structure with the main column 3 as the vertical axis.

[0032] Furthermore, for example, if the floating structure 1 has a three-dimensional truss structure in the shape of a square pyramid, there will be three vertices where the main column 3 is not located. In this case, sub-columns 5 may be placed at all vertices, or sub-columns 5 may be placed at only at least two vertices.

[0033] Next, the floating structure 1 according to the second embodiment will be described with reference to Figures 3 to 4(C). Note that the same reference numerals are used for components identical to those in the first embodiment described above, and redundant explanations are omitted.

[0034] Here, Figure 3 is a perspective view showing the floating structure in use according to the second embodiment. Figure 4 is an explanatory diagram of the floating structure shown in Figure 3, where (A) is a plan view, (B) is a side view seen from direction B in Figure 3(A), and (C) is a side view seen from direction C in Figure 3(A). Note that in each of the figures in Figure 4, the diagrams of the superstructure (wind turbine) have been omitted for the sake of explanation.

[0035] The floating structure 1 according to the second embodiment has three sub-columns 5. Specifically, as shown in Figure 3, a third sub-column 53 is added to the floating structure 1 according to the first embodiment. The third sub-column 53 is positioned on a support member 7 connected to the vertices (second vertex 2b and third vertex 2c) of the lower structure 2 where the main column 3 is not located.

[0036] As shown in Figures 4(A) to 4(C), the support member 7 comprises a first support member 71 positioned between the first sub-column 51 and the third sub-column 53, and a second support member 72 positioned between the second sub-column 52 and the third sub-column 53. The support member 7 may be made of a plate material, or it may be in a cylindrical shape with a cavity inside.

[0037] In this way, by forming a truss structure with the support members 7 (first support member 71 and second support member 72) and the third frame 23, the strength of the support structure of the third sub-column 53 can be increased.

[0038] Furthermore, although not shown in the diagram, the number of sub-columns 5 can be further increased by similarly increasing the number of truss-shaped support members 7. For example, by configuring the support members 7 to form a triangular truss structure including a first support member 71 and a triangular truss structure including a second support member 72, it becomes possible to arrange four or more sub-columns 5.

[0039] Next, the floating structure 1 according to the third embodiment will be described with reference to Figures 5 to 6(C). Note that the same reference numerals are used for components identical to those in the first embodiment described above, and redundant explanations are omitted.

[0040] Here, Figure 5 is a perspective view showing the floating structure in use according to the third embodiment. Figure 6 is an explanatory diagram of the floating structure shown in Figure 5, where (A) is a plan view, (B) is a side view seen from direction B in Figure 5(A), and (C) is a side view seen from direction C in Figure 5(A). Note that in each of the figures in Figure 5, the diagrams of the superstructure (wind turbine) have been omitted for the sake of explanation.

[0041] The floating structure 1 according to the third embodiment, as shown in Figures 5 to 6(C), comprises a substructure 20 composed of two triangular frames including a shared side, a main column 3 positioned at one of the vertices (first vertex 20a) located at both ends of the shared side, a connecting member 4 connecting the main column 3 to the remaining vertices (second vertex 20b, third vertex 20c, fourth vertex 20d) of the substructure 20 where the main column 3 is not positioned, subcolumns 5 (first subcolumn 51 and second subcolumn 52) positioned at the remaining vertices (second vertex 20b and third vertex 20c) of the substructure 20 that do not include the shared side, and a subcolumn 5 (third subcolumn 53) positioned via a support member 70 connected to the vertex (fourth vertex 20d) at both ends of the shared side of the substructure 2 where the main column 3 is not positioned.

[0042] The main column 3 and sub-column 5 have the same configuration as those of the first embodiment described above. In addition, protrusions 8 for connecting mooring ropes (not shown) may be arranged at the lower part of the main column 3 and sub-column 5.

[0043] The lower structure 20 has a rectangular shape formed by two triangular frames, with one shared side located on the diagonal of the rectangle. Here, the outer shape of the lower structure 20 has four vertices, and as shown in Figure 6(A), the vertex where the main column 3 is located will be called the first vertex 20a, the vertex where the first sub-column 51 is located will be called the second vertex 20b, the vertex where the second sub-column 52 is located will be called the third vertex 20c, and the vertex where the support member 70 is located will be called the fourth vertex 20d.

[0044] The lower structure 20 includes a first frame 201 disposed between the first vertex portion 20a and the fourth vertex portion 20d, a second frame 202 disposed between the first vertex portion 20a and the second vertex portion 20b, a third frame 203 disposed between the second vertex portion 20b and the fourth vertex portion 20d, a fourth frame 204 disposed between the first vertex portion 20a and the third vertex portion 20c, and a fifth frame 205 disposed between the third vertex portion 20c and the fourth vertex portion 20d. The first frame 201 is a member that constitutes a common side shared by two triangular shapes.

[0045] The first frame 201 and the second frame 202 may be directly connected or may be connected via the main column 3. The first frame 201 and the fourth frame 204 may be directly connected or may be connected via the main column 3. The second frame 202 and the third frame 23 may be directly connected or may be connected via the first sub-column 51. The fourth frame 204 and the fifth frame 205 may be directly connected or may be connected via the second sub-column 52.

[0046] The first frame 201 to the fifth frame 205 may be formed of a plate material or may be formed in a cylindrical shape having a cavity inside. Also, a ballast tank may be disposed inside the first frame 201 to the fifth frame 205.

[0047] In the illustrated lower structure 20, the first frame 201, the third frame 203, and the fifth frame are formed relatively thick, and the second frame 202 and the fourth frame 204 are formed relatively thin, but the structure is not limited to such a configuration.

[0048] The connecting member 4 is a diagonal member that connects the lower structure 20 and the main column 3. The connecting member 4 includes a first connecting member 41 having one end connected to the upper part of the main column 3 and the other end connected to the range of the fourth apex portion 20d of the first frame 201, a second connecting member 42 having one end connected to the upper part of the main column 3 and the other end connected to the range of the second apex portion 20b of the second frame 22, and a third connecting member 43 having one end connected to the upper part of the main column 3 and the other end connected to the range of the third apex portion 20c of the fourth frame 24.

[0049] The support member 70 has one end connected to the range of the fourth apex portion 20d and the other end connected to the third sub-column 53. By arranging the support member 70 for arranging the third sub-column 53 at the fourth apex portion 20d and adjusting the length and thickness of the support member 70, the buoyancy and restoring force of the floating structure 1 can be adjusted.

[0050] For example, the support member 70 may be formed relatively thicker than the first frame 201, the third frame 203, and the fifth frame, or may be formed relatively shorter than the first frame 201, the third frame 203, and the fifth frame.

[0051] Of course, the buoyancy and restoring force of the floating structure 1 can also be adjusted by the thickness (diameter) of the main column 3 and the sub-columns 5, the size of the ballast tank, etc. In the illustrated third embodiment, the first sub-column 51 and the second sub-column 52 are formed thinner (smaller diameter) than the main column 3, and the third sub-column 53 has the same thickness (diameter) as the main column 3. Although not shown, all the sub-columns 5 may be formed with the same thickness, or the main column 3 and all the sub-columns 5 may be formed with the same thickness.

[0052] Although not shown, the support member 70 and the third sub-column 53 may be omitted. Also, although not shown, the support member 70 may be omitted and the third sub-column 53 may be arranged at the fourth apex portion 20d. At this time, by adjusting the conditions such as the length, thickness, and intersection angle of the first frame 201 to the fifth frame 205 constituting the lower structure 20, the buoyancy and restoring force of the floating structure 1 can be adjusted.

[0053] The floating structure 1 according to the third embodiment is composed of a three-dimensional truss structure consisting of a substructure 20 (first frame 201, second frame 202, third frame 203, fourth frame 204, and fifth frame 205), a main column 3, and connecting members 4 (first connecting member 41, second connecting member 42, and third connecting member 43). By using a three-dimensional truss structure as the foundation, the rigidity of the floating structure 1 can be increased, and the required strength can be secured with less steel weight than in conventional designs.

[0054] Therefore, according to the floating structure 1 of this embodiment, even when the wind turbine 6, which is the superstructure, is enlarged, the strength of the floating structure 1 can be easily increased, and resonance with the natural frequencies of the wind turbine 6 and its blades can be easily avoided.

[0055] The floating structure 1 according to the third embodiment described above has a three-dimensional truss structure with a square pyramidal shape with the main column 3 as the vertical axis, but is not limited to this configuration. For example, although not shown, the floating structure 1 may have a three-dimensional truss structure with a polygonal pyramidal shape, such as a pentagonal pyramidal shape, with the main column 3 as the vertical axis.

[0056] The present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0057] 1 Floating structure, 2, 20 Substructure, 2a, 20a First vertex, 2b, 20b Second vertex, 2c, 20c Third vertex, 3 Main column, 4 Connecting member, 5 Subcolumn, 6 Wind turbine, 7, 70 Support member, 8 Protrusion, 20d Fourth vertex, 21, 201 First frame, 22, 202 Second frame, 23, 203 Third frame, 24, 204 Fourth frame, 41 First connecting member, 42 Second connecting member, 43 Third connecting member, 51 First subcolumn, 52 Second subcolumn, 53 Third subcolumn, 71 First support member, 72 Second support member, 205 Fifth frame

Claims

1. A floating structure comprising a substructure composed of a triangular frame, a main column positioned at one of the vertices of the substructure, and a connecting member connecting the remaining vertices of the substructure where the main column is not positioned to the main column, wherein the substructure, the main column, and the connecting member constitute a three-dimensional truss structure.

2. The floating structure according to claim 1, further comprising a sub-column positioned at the apex of the lower structure where the main column is not located.

3. The floating structure according to claim 2, further comprising a sub-column positioned via a support member connected to the apex portion of the substructure where the main column is not located.

4. The floating structure according to claim 1, wherein the three-dimensional truss structure has a polygonal pyramidal shape with the main column as the vertical axis.

5. A floating structure comprising a substructure composed of two triangular frames including a shared side, a main column positioned at one of the vertices located at both ends of the shared side, and a connecting member connecting the remaining vertices of the substructure where the main column is not located to the main column, wherein the substructure, the main column, and the connecting member constitute a three-dimensional truss structure.

6. The floating structure according to claim 5, further comprising a sub-column positioned at a vertex where the main column is not located.

7. The floating structure according to claim 5, comprising a sub-column positioned at the remaining vertices of the substructure that do not include the shared side.

8. The floating structure according to claim 7, further comprising subcolumns positioned via support members connected to the vertices of the shared side of the substructure where the main column is not located.

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