Joint, tower support structure, floating body structure, and offshore wind power generation facility

Abstract

A joint 80 comprises: a cylindrical part 82 having an inner peripheral surface 82a and an outer peripheral surface 82b; a projection part 84 concentric with the cylindrical part 82 and forming an annular shape projecting in a radial direction from the outer peripheral surface 82b, the projection part 84 having end surfaces 84a, 84b facing in an axial direction; and a first connection part 86 forming the annular shape concentric with the cylindrical part 82 between the cylindrical part 82 and the projection part 84, the first connection part 86 continuously connecting the outer peripheral surface 82b and the end surfaces 84a, 84b. The cylindrical part 82, the projection part 84, and the first connection part 86 are integrally formed from the same forged material 80S.

Description

Joints, tower support structures, floating structures, offshore wind power generation facilities

[0001] The present disclosure relates to a joint, a tower support structure, a floating structure, and an offshore wind power generation facility.

[0002] One example of an offshore wind power generation facility is described in Japanese Patent Laid-Open No. 2023-124020 (hereinafter referred to as Patent Document 1), which includes a tension-moored float, a bottom mooring, tension mooring lines, and a wind power generation facility. In this type of offshore wind power generation facility, a joint is used to connect the base of the tower structure supporting the wind power generation facility to the column of the tension-moored float on which the tower structure is attached.

[0003] The conventional joint has a cylindrical portion that is welded to the tower structure and a ring-shaped protruding portion that protrudes radially from the outer periphery of the cylindrical portion and is welded to the tension-moored float. In the conventional joint, the cylindrical portion and the protruding portion are each constructed as separate bodies. The conventional joint has a triangular bracket that welds the cylindrical portion to the protruding portion.

[0004] In recent years, there has been a demand for even higher power output from individual offshore wind power generation facilities. To meet this demand, the enlargement of wind power generation facilities and tower structures has been considered. Specifically, wind power generation facilities with larger and higher power output than conventional structures are being considered, with tower structures having a diameter of 7.8 m or more. In this case, the cyclic loads imposed on the offshore wind power generation facility due to the rotational motion of the wind power generation facility's blades, waves, wind, etc. increase as the wind power generation facility and tower structure become larger. Therefore, each member supporting the tower structure is required to have a fatigue life sufficient to withstand the cyclic loads that increase with the enlargement of the wind power generation facility and tower structure over a long period of time. In other words, to meet the demand for higher power output from offshore wind power generation facilities, the joints connecting the tower structure and the tension-moored floating body are required to have a fatigue life longer than conventional structures.

[0005] The present disclosure aims to improve the fatigue life of a joint when joining the base of a tower structure installed offshore and the column portion of a floating structure, compared to a configuration in which the cylindrical portion and the protruding portion are separate and joined by welding.

[0006] A first aspect of the present disclosure is a joint for joining a base of a tower structure to be installed offshore and a column of a floating structure, the joint comprising: a cylindrical portion having an inner peripheral surface and an outer peripheral surface, a ring-shaped protruding portion concentric with the cylindrical portion and protruding radially from the outer peripheral surface, the protruding portion having an end face facing in the axial direction, and a first connecting portion between the cylindrical portion and the protruding portion, the first connecting portion being concentric with the cylindrical portion and continuously connecting the outer peripheral surface and the end face, the cylindrical portion, the protruding portion, and the first connecting portion being integrally formed from the same forged material.

[0007] According to the present disclosure, when joining the base of a tower structure installed offshore and the column portion of a floating structure, the fatigue life of the joint can be improved compared to a configuration in which the cylindrical portion and the protruding portion are separate and joined by welding.

[0008] 9 is a schematic diagram of an offshore wind power generation facility according to an embodiment. A perspective view of a floating body structure according to an embodiment. A plan view of the column section and its surroundings of the floating body structure according to an embodiment. A cross-sectional view taken along line 4-4 of FIG. 3. A cross-sectional view of a tower support structure according to an embodiment. A perspective view of a joint according to an embodiment. A cross-sectional view of a joint according to an embodiment. A cross-sectional view of a material for a joint according to an embodiment. A perspective view of a bracket according to an embodiment. A view taken along arrow B of FIG. 9. A perspective view of a joint according to a comparative embodiment. A cross-sectional view of a joint according to a comparative embodiment. A cross-sectional view of a joint according to a modified embodiment. A cross-sectional view of a tower support structure according to a modified embodiment. A cross-sectional view of a joint according to a modified embodiment. A partial cross-sectional perspective ...

[0009] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. The drawings are not necessarily to scale, and some features may be exaggerated or omitted. In the following description, the normal direction (up-down direction, vertical direction, or height direction) to the water surface S will be referred to as the Z direction. Furthermore, when the water surface S is used as a reference, the atmosphere side (upper side) of the water surface S will be referred to as the +Z side, and the bottom side (lower side) of the water surface S will be referred to as the -Z side.

[0010] 1 is a schematic diagram of an offshore wind power generation facility 10 according to the present disclosure. The offshore wind power generation facility 10 is arranged offshore using a TLP (Tension Leg Platform) system. As shown in FIG. 1 , the offshore wind power generation facility 10 includes a wind turbine 20, a floating structure 30, mooring lines 34, and mooring portions 36.

[0011] The floating structure 30 floats on the ocean, and the wind turbine generator 20 is disposed on a portion that is exposed to the atmosphere more than the water surface S. The floating structure 30 is maintained in its position on the ocean by mooring lines 34 and mooring parts 36. Details of the floating structure 30 will be described later.

[0012] The mooring portion 36 is a foundation structure placed on the seabed B. The mooring portion 36 maintains the position of the offshore wind power generation facility 10 via the mooring lines 34. The mooring portion 36 is, for example, a foundation pile. The mooring portion 36 is, for example, a gravity anchor, a pile anchor, or a suction anchor. The mooring portion 36 has a connecting portion such as a hook or ring (not shown) for connecting to the mooring lines 34.

[0013] The mooring lines 34 connect the floating structure 30 to the mooring portion 36. The mooring lines 34 are made of steel rods, steel ropes, fiber ropes, or the like.

[0014] The wind turbine generator 20 converts wind power into electric power and outputs the electric power. The wind turbine generator 20 is disposed on a tower structure 50 of a floating structure 30, which will be described later. The wind turbine generator 20 has a nacelle 22, a boss 24, and blades 26.

[0015] The nacelle 22 is disposed at the upper end of the tower structure 50. The nacelle 22 has a hollow cylindrical shape extending horizontally. The nacelle 22 houses a generator, a transmission mechanism, and a brake device (not shown). The generator converts rotational force transmitted from the boss 24, which rotates about the axis of the nacelle 22, via the transmission mechanism into electric power. The transmission mechanism transmits the rotational force between the boss 24 and the generator. The transmission mechanism includes a transmission device such as a gearbox. As described below, the blades 26 receive wind force, causing the boss 24 to rotate at a first rotational speed. The transmission mechanism receives the rotational force from the boss 24, which rotates at the first rotational speed. The transmission mechanism converts the rotational force transmitted from the boss 24 into rotational force having a second rotational speed via the transmission device and transmits the rotational force to the generator. The second rotational speed is preferably greater than the first rotational speed. The brake device transmits a braking force to the boss 24 to place the boss 24 in a non-rotating state.

[0016] The boss 24 is provided at one end in the axial direction of the nacelle 22. The boss 24 is cylindrical and extends along the axial direction of the nacelle 22. The boss 24 is rotatable around the axial direction of the nacelle 22. The boss 24 has a shaft portion (not shown) that extends in the axial direction. The shaft portion is connected to a transmission mechanism.

[0017] The blades 26 are integrally provided with the boss 24 so as to protrude from the cylindrical surface of the boss 24. A plurality of blades 26 are provided on the cylindrical surface of the boss 24. The blades 26 have an aerofoil cross section. When subjected to wind force, the blades 26 rotate around the boss 24 in the CW direction (clockwise in FIG. 1 ), causing the boss 24 to rotate in the CW direction. In other words, the blades 26 convert the wind force into rotational force for the boss 24.

[0018] 1 and 2 , the floating structure 30 has three column sections 40a, 40b, and 40c, three braces 31a, 31b, and 31c, three pontoons 32a, 32b, and 32c, and a tower structure 50. The floating structure 30 further has a tower support structure 60.

[0019] The column sections 40 a, 40 b, 40 c, the braces 31 a, 31 b, 31 c, and the pontoons 32 a, 32 b, 32 c are each made of steel, and the steel used to make the column sections 40 a, 40 b, 40 c, the braces 31 a, 31 b, 31 c, and the pontoons 32 a, 32 b, 32 c is preferably a shipbuilding steel or a high-tensile steel for a ship hull specified by a classification society of any country.

[0020] In a plan view facing the water surface S, the floating structure 30 has an equilateral triangular shape with the three column sections 40a, 40b, and 40c as vertices and the three braces 31a, 31b, and 31c as sides (see Figure 2).

[0021] Each of the column sections 40a, 40b, and 40c is a floating body that floats in water. As shown in FIG. 2, each of the column sections 40a, 40b, and 40c is a hexagonal column-shaped structure extending vertically. As shown in FIG. 1, each of the column sections 40a, 40b, and 40c is moored by a mooring line 34 and a mooring section 36 with its upper end exposed to the atmosphere above the water surface S and its lower end submerged below the water surface S. A tower structure 50 is disposed on the column section 40a. The column section 40a will be described in detail below.

[0022] As shown in Figure 2, the braces 31a, 31b, and 31c are each columnar and connect the upper ends of the column sections 40a, 40b, and 40c. The brace 31a connects the upper end of the column section 40a to the upper end of the column section 40b. The brace 31b connects the upper end of the column section 40b to the upper end of the column section 40c. The brace 31c connects the upper end of the column section 40c to the upper end of the column section 40a. The braces 31a, 31b, and 31c are provided on two side surfaces of the hexagonal column sections 40a, 40b, and 40c, respectively, that sandwich the side closest to the center of the equilateral triangle formed by the floating structure.

[0023] As shown in Fig. 2, the pontoons 32a, 32b, and 32c are each columnar and connect the lower ends of the column sections 40a, 40b, and 40c. The pontoon 32a connects the lower end of the column section 40a to the lower end of the column section 40b. The pontoon 32b connects the lower end of the column section 40b to the lower end of the column section 40c. The pontoon 32c connects the lower end of the column section 40c to the lower end of the column section 40a. The pontoons 32a, 32b, and 32c are provided on two side surfaces of the hexagonal column sections 40a, 40b, and 40c, respectively, that sandwich the side surface closest to the center of the equilateral triangle formed by the floating structure.

[0024] <Tower Structure 50> The tower structure 50 is provided on the column section 40a and has a cylindrical shape extending in the vertical direction. The tower structure 50 has a diameter of 7 m or more. The tower structure 50 of this embodiment also has a diameter of 7.9 m or more. The tower structure 50 has a diameter of 13 m or less. The tower structure 50 of this embodiment has a diameter of approximately 8 m. In this embodiment, the height from the top of the tower structure 50 to the deck section 44a of the column section 40a (described in detail below) is determined by the longitudinal length of the blade 26 and the height of the column section 40a. The tower structure 50 has a main body section 52 and a base section 54.

[0025] The main body 52 has a hollow cylindrical shape extending in the vertical direction. The main body 52 has an imaginary axis C as its central axis. The wind turbine generator 20 is disposed at the upper end of the main body 52. ​​As shown in FIG. 4 , the main body 52 has a flange 52a. The flange 52a protrudes from the inner circumferential surface of the lower end of the main body 52 toward the imaginary axis C, and forms the lower end face of the main body 52. ​​The flange 52a is annular with the imaginary axis C as its central axis.

[0026] The base 54 is a hollow cylinder disposed below the main body 52 and coaxially overlaps the main body 52. ​​The base 54 is disposed above the deck 44a of the column 40a. As shown in FIG. 4 , the base 54 has a flange 54a and a rib 54b. The flange 54a protrudes from the inner circumferential surface of the upper end of the base 54 toward the imaginary axis C and forms the upper end face of the base 54. The flange 54a is annular and overlaps with the flange 52a of the main body 52 in a plan view. The flange 54a is connected to the flange 52a of the main body 52 by a connecting portion 56, thereby connecting the main body 52 and the base 54. The connecting portion 56 is, for example, a bolt and nut fastener. The rib 54b is plate-shaped and protrudes from the inner circumferential surface of the base 54 toward the imaginary axis C and has a surface facing vertically. The rib portion 54b has an annular shape with the imaginary axis C as its central axis. The rib portion 54b reinforces the base portion 54.

[0027] <Tower Support Structure 60> The tower support structure 60 supports the tower structure 50 at the column portion 40a. As shown in Figure 4, the tower support structure 60 has the column portion 40a, the base portion 54 of the tower structure 50, and a joint 80.

[0028] As shown in Figures 2 and 3, the column portion 40a has a hexagonal prism shape in which the tower structure 50 is disposed. The column portion 40a has a hollow structure. As shown in Figure 4, the column portion 40a has an inner diameter portion 42, a deck portion 44a, and a bracket 70. The column portion 40a further has a bracket 47 and a stiffener portion 48. Note that, as shown in Figure 3, the column portion 40a has a plurality of brackets 70 provided so as to surround the inner diameter portion 42 in a plan view.

[0029] As shown in FIG. 4, the deck portion 44a is a plate-like structure that forms the upper end surface of the column portion 40a. The outer shape of the deck portion 44a is hexagonal in a plan view. The deck portion 44a has a surface facing the axial direction of the tower structure 50. The deck portion 44a is configured to have a hole H. The hole H is a circular hole configured to overlap with the tower structure 50 (or the inner diameter portion 42 described below) and the joint 80 in the vertical direction. The central axis of the hole H is the imaginary axis C. In other words, the deck portion 44a is provided radially outward from the inner diameter portion 42.

[0030] As shown in Figures 3 and 4, the deck portion 44a has a rib portion 45a and a flange portion 45b. The rib portion 45a is provided so as to protrude toward the bottom from the surface of the deck portion 44a facing the bottom, and is plate-shaped with a surface facing in the radial direction of the tower structure 50. The rib portion 45a is annular with the imaginary axis C as its central axis. The rib portion 45a reinforces the deck portion 44a. The flange portion 45b is provided so as to protrude in the radial direction from the end of the rib portion 45a facing the bottom, and is plate-shaped with a surface facing in the vertical direction. The flange portion 45b is annular with the imaginary axis C as its central axis. The flange portion 45b reinforces the rib portion 45a.

[0031] As shown in Figures 3 and 4, the inner diameter portion 42 is a hollow cylinder that overlaps the main body portion 52 and the base portion 54 coaxially in a plan view and is located on the opposite side of the joint 80 from the base portion 54. The inner diameter portion 42 is located below the deck portion 44a. As shown in Figure 4, the inner diameter portion 42 has a rib portion 43. The rib portion 43 is provided so as to protrude from the inner peripheral surface of the inner diameter portion 42 toward the imaginary axis C and is plate-shaped with a surface facing vertically. The rib portion 43 is annular with the imaginary axis C as its central axis. The rib portion 43 overlaps with the rib portion 54b in a plan view. The rib portion 43 reinforces the inner diameter portion 42.

[0032] 4, the stiffener portion 48 is provided so as to connect the inner peripheries of the rib portions 43, 54b, and has a hollow cylindrical shape with its central axis coincident with the imaginary axis C. The stiffener portion 48 reinforces the rib portions 43, 54b.

[0033] As shown in FIG. 4 , the bracket 47 is disposed in the closed space CS surrounded by the structures of the base 54, the joint 80, the inner diameter portion 42, and the stiffener portion 48, and is a plate-like member that welds these structures together. Specifically, the bracket 47 is joined to the inner peripheral surfaces of the base 54, the joint 80, and the inner diameter portion 42. The bracket 47 is joined to the upper surface of the rib portion 43 and the lower surface of the rib portion 54b. The bracket 47 is joined to the outer peripheral surface of the stiffener portion 48. The bracket 47 has a cutout portion 47a. The cutout portion 47a overlaps with a corner of the closed space CS formed by the rib portion 43 and the stiffener portion 48. The cutout portion 47a prevents the bracket 47 from being joined to a portion of the rib portion 43 or the stiffener portion 48. A plurality of brackets 47 are provided along the circumferential direction of the outer peripheral surface of the stiffener portion 48 .

[0034] 4 and 9, the bracket 70 is a plate-like member that is welded to the outer peripheral surface of the inner diameter portion 42 and the lower surface of the deck portion 44a. The bracket 70 has a surface that faces the circumferential direction of the inner diameter portion 42. The thickness of the bracket 70 is preferably within a range of 20 mm to 80 mm.

[0035] The bracket 70 has joints 71 and 72, peripheral edges 73 and 74, an edge 75, and corners 76, 77, 78, and 79. The joints 71 and 72, the peripheral edges 73 and 74, and the edge 75 are each outer edge that defines the outer shape of the bracket 70, as shown in Figures 9 and 10 .

[0036] As shown in Fig. 4, the joint portion 71 is joined by welding to the outer peripheral surface of the inner diameter portion 42. The joint portion 72 is joined by welding to the lower surface of the deck portion 44a, which is on the outer peripheral side of the rib portion 45a. The peripheral edge portion 73 faces the joint portion 71 with the joint portion 72 in between. The peripheral edge portion 74 faces the joint portion 72 with the joint portion 71 in between.

[0037] As shown in Fig. 10, the peripheral edge portion 73 and the peripheral edge portion 74 are connected to each other and form a corner portion 76. In other words, the corner portion 76 connects the peripheral edge portion 73 and the peripheral edge portion 74. The peripheral edge portion 73 and the joint portion 72 are connected to each other and form a corner portion 77. In other words, the corner portion 77 connects the peripheral edge portion 73 and the joint portion 72. The peripheral edge portion 74 and the joint portion 71 are connected to each other and form a corner portion 78. In other words, the corner portion 78 connects the peripheral edge portion 74 and the joint portion 71. The imaginary line segment connecting the corner portion 77 and the corner portion 78 is called a diagonal line 70d.

[0038] 4, the end of the joint 71 opposite the corner 78 and the end of the joint 72 opposite the corner 77 do not reach the joint 80. In other words, the ends of the joints 71 and 72 on the joint 80 side are not in contact with the joint 80 and are not joined to the joint 80.

[0039] The edge portion 75 connects the end of the joint portion 71 on the joint 80 side and the end of the joint portion 72 on the joint 80 side. The edge portion 75 is not in contact with and is not joined to the joint 80. The edge portion 75, together with the inner diameter portion 42, the joint 80, and the deck portion 44a, defines a cutout portion 75c. The cutout portion 75c is a space surrounded by the edge portion 75, the inner diameter portion 42, the joint 80, and the deck portion 44a when the bracket 70 is viewed from the plate surface side. In other words, the bracket 70 has the cutout portion 75c surrounded by the edge portion 75. The edge portion 75 has a curved portion 75a and a joint portion 75b.

[0040] 4 and 9, the joint portion 75b is a portion that is joined to the rib portion 45a by welding. The joint portion 75b is connected to the joint portion 72 and forms a corner portion 79. In other words, the corner portion 79 connects the joint portion 72 and the joint portion 75b.

[0041] As shown in Figures 4 and 10, the curved portion 75a is a curved portion of the edge portion 75 when the bracket 70 is viewed from the plate surface side. In this embodiment, the curved portion 75a extends from the end of the joint 71 on the joint 80 side and curves toward the lower end of the joint 75b. That is, the curved portion 75a curves in a direction away from the joint 80. The curved portion 75a is formed from the end of the joint 71 on the joint 80 side and the lower end of the joint 75b so as to straddle the diagonal line 70d. That is, the cutout portion 75c surrounded by the edge portion 75 extends toward the corner 76 beyond the diagonal line 70d.

[0042] <Joint 80> As shown in Figures 4 and 5, the joint 80 is a structural member that is disposed between the base portion 54, the inner diameter portion 42, and the deck portion 44a and joined by welding. The joint 80 is machined from a hollow cylindrical joint material 80S shown in Figure 8, to form an annular shape having a T-shaped cross section that protrudes horizontally as shown in Figures 6 and 7. The joint 80 has a cylindrical portion 82, a protruding portion 84, and a first connecting portion 86.

[0043] The cylindrical portion 82 has a hollow cylindrical shape that extends substantially uniformly along the imaginary axis C. The cylindrical portion 82 is arranged so as to overlap the base portion 54 coaxially in a plan view. The cylindrical portion 82 has an inner circumferential surface 82a and an outer circumferential surface 82b. The inner circumferential surface 82a has a diameter of 7 m or more. The inner circumferential surface 82b has a diameter of 12.9 m or less. One end of the cylindrical portion 82 is joined by welding to the base portion 54 of the tower structure 50, as shown in FIG. 5 . The end of the cylindrical portion 82 opposite the base portion 54 is joined by welding to the inner diameter portion 42 of the column portion 40a.

[0044] As shown in Fig. 5, the protruding portion 84 is in the form of a plate that protrudes radially from the outer circumferential surface 82b. The protruding portion 84 is annular and concentric with the cylindrical portion 82. As shown in Figs. 6 and 7, the protruding portion 84 has an end face 84a and an end face 84b. The end face 84a faces in a direction along the imaginary axis C. The end face 84b faces in the opposite direction to the end face 84a. Specifically, the end face 84a faces in the +Z direction. The end face 84b faces in the -Z direction.

[0045] The first connection portions 86 are corners of the joint 80 located between the cylindrical portion 82 and the protruding portion 84. The first connection portions 86 connect the outer peripheral surface 82b to each of the end faces 84a, 84b over the entire circumferential direction. In other words, the first connection portions 86 are provided on both the vertically upper and lower sides of the protruding portion 84. The joint 80 has two first connection portions 86. The first connection portions 86 are annular and concentric with the cylindrical portion 82. The first connection portions 86 have corner rounded surfaces 86a.

[0046] 6 and 7, the corner rounded surface 86a is a curved surface that defines the outer shape of the first connecting portion 86. In the cross-sectional view shown in Fig. 7, the corner rounded surface 86a has an arc shape with a radius RC that continuously connects the outer circumferential surface 82b and each of the end surfaces 84a, 84b. The corner rounded surface 86a is annular and concentric with the cylindrical portion 82.

[0047] The cylindrical portion 82, the protruding portion 84, and the first connecting portion 86 shown in Fig. 7 are formed by machining the joint material 80S shown in Fig. 8. That is, the cylindrical portion 82, the protruding portion 84, and the first connecting portion 86 are integrally formed from the same joint material 80S.

[0048] In this embodiment, the cylindrical portion 82 and the protruding portion 84 have a maximum wall thickness of 150 mm. In other words, the cylindrical portion 82 and the protruding portion 84 have a wall thickness that is a ratio of a maximum of 1.8% to the diameter of the tower structure 50, which is 8 m. That is, the ratio of the maximum wall thickness of the cylindrical portion 82 and the protruding portion 84 to the diameter of the tower structure 50 is 1.0% or more and 2.0% or less.

[0049] As shown in Figure 8, the joint material 80S is a hollow cylindrical steel material. The joint material 80S is a forged material. The joint material 80S is preferably a forged material specified by a classification society of any country or a forged material specified by an industrial standard of any country. The joint material 80S has a shape in which the outer shape of the joint 80 is offset by a machining allowance.

[0050] Next, the operation and effects of the present disclosure will be described. In this description, a joint H80 will be described as a comparative example to the embodiment, using Figures 11 and 12. In describing the joint H80, when parts and the like similar to those of the joint 80 of the embodiment are used, the symbols and names of those parts and the like will be used as they are.

[0051] As shown in FIG. 11, the comparative joint H80 has a cylindrical portion H82, a protruding portion H84, and a triangular bracket H86 instead of the cylindrical portion 82, the protruding portion 84, and the first connecting portion 86 of the embodiment.

[0052] The cylindrical portion H82 is a hollow cylindrical member corresponding to the cylindrical portion 82 of the embodiment.

[0053] The protrusion H84 is a member corresponding to the protrusion 84 of the embodiment. The protrusion H84 is annular and concentric with the cylindrical portion H82. The protrusion H84 is a separate member from the cylindrical portion H82.

[0054] The triangular brackets H86 are welded to the outer peripheral surface H82b of the cylindrical portion H82 and the end faces H84a, H84b of the protruding portion H84. A plurality of triangular brackets H86 are provided along the circumferential direction of the outer peripheral surface H82b. The joint H80 has five triangular brackets H86.

[0055] The cylindrical portion H82, the protruding portion H84, and the triangular bracket H86 are each formed from a steel material having properties equivalent to those of the steel material forming the joint 80 of the embodiment.

[0056] Other than the above, the comparative joint H80 has the same configuration as the joint 80.

[0057] The cylindrical portion H82 and the protruding portion H84 of the joint H80 of the comparative embodiment are separate bodies and are joined to the triangular bracket H86 by welding. Therefore, the fatigue strength around the welded portions between the triangular bracket H86 of the joint H80 and the cylindrical portion H82 and the protruding portion H84 is lower than the fatigue strength of each of the base materials, i.e., the cylindrical portion H82, the protruding portion H84, and the triangular bracket H86. On the other hand, the cylindrical portion 82, the protruding portion 84, and the first connecting portion 86 of the joint 80 of the embodiment are integrally formed from the same joint material 80S. Therefore, the fatigue strength around the boundaries between the first connecting portion 86 of the joint 80 and the cylindrical portion 82 and the protruding portion 84 is higher than the fatigue strength around the welded portions of the joint H80 of the comparative embodiment. Therefore, according to the joint 80 of the tower support structure 60 of the embodiment of the offshore wind power generation facility 10, when a joint is used to join the base 54 of the tower structure 50 installed offshore and the column portion 40a of the floating structure 30, the fatigue life of the joint 80 can be improved compared to the comparative joint H80.

[0058] In particular, when the tower structure 50 has a diameter of 7 m or more, the fatigue load acting on the welded portion of the joint H80 increases, thereby reducing the fatigue life of the joint H80. On the other hand, in the joint 80 of the embodiment, the cylindrical portion 82, the protruding portion 84, and the first connecting portion 86 are integrally formed from the joint material 80S, and therefore the joint 80 has sufficient fatigue strength against the fatigue load acting around the boundaries between the first connecting portion 86 and each of the cylindrical portion 82 and the protruding portion 84. Therefore, according to the joint 80 of the embodiment, the fatigue life of the joint 80 can be improved when the tower structure 50 has a diameter of 7 m or more.

[0059] The inner circumferential surface 80a of the joint 80 has a diameter of 7 m or more. As the diameter of the inner circumferential surface of the cylindrical portion increases, the thickness of the cylindrical portion of the joint decreases. In this case, the fatigue strength of a joint having an aspect in which the protruding portion and the cylindrical portion are separate and joined by a joint bracket, as in the comparative example, decreases. In particular, when the ratio of the maximum thickness of the cylindrical portion and the protruding portion to the diameter of the tower structure 50 is 1.0% or more and 2.0% or less, the fatigue strength of a joint having the comparative example decreases. On the other hand, the joint 80 of the embodiment has sufficient fatigue strength even when the inner circumferential surface 80a has a diameter of 7 m or more because the cylindrical portion 82, the protruding portion 84, and the first connecting portion 86 are integrally formed from the same joint material 80S. Furthermore, the joint 80 of the embodiment has sufficient fatigue strength even when the ratio of the maximum thickness of the cylindrical portion 82 and the protruding portion 84 to the diameter of the tower structure 50 is 1.0% or more and 2.0% or less. Therefore, according to the joint 80 of the embodiment, when the inner circumferential surface 80a has a diameter of 7 mm or more, it is possible to improve the fatigue life of the joint 80. Furthermore, according to the joint 80 of the embodiment, when the ratio of the maximum thickness of the cylindrical portion 82 and the protruding portion 84 to the diameter of the tower structure 50 is 1.0% or more and 2.0% or less, it is possible to improve the fatigue life of the joint 80.

[0060] A comparative fatigue life test was conducted by numerical simulation using the finite element method between a floating structure having the comparative joint H80 and a floating structure 30 having the joint 80 of the embodiment. As a result, the fatigue life of the floating structure having the comparative joint H80 was approximately 7 years. On the other hand, the fatigue life of the floating structure having the joint 80 of the embodiment was approximately 330 years. Thus, the comparative test by numerical simulation confirmed that the joint 80 of the embodiment has a longer fatigue life than joints of conventional structures. The calculation conditions for the comparative test by numerical simulation conformed to the guidelines established by the classification society.

[0061] The joint 80 has an annular first connection portion 86. Therefore, the stress generated in the first connection portion 86 of the joint 80 due to operation of the offshore wind power generation facility is smaller than the stress generated in the triangular bracket H86 provided in the joint H80 of the comparative embodiment. Therefore, the joint 80 can improve the fatigue life of the first connection portion 86 compared to the joint H80 of the comparative embodiment. In particular, the first connection portion 86 has a corner R surface 86a. Therefore, the joint 80 can further improve the strength of the first connection portion 86. Therefore, the joint 80 can further improve the fatigue life of the first connection portion 86.

[0062] The tower support structure 60 further includes a bracket 70. Therefore, the tower support structure 60 can improve the fatigue life of the tower support structure 60.

[0063] The joints 71, 72 and the edge 75 of the bracket 70 are not joined to the joint 80. As a result, the load of the tower structure 50 is not directly transmitted from the joint 80 to the bracket 70. In other words, the load of the tower structure 50 is transmitted to the bracket 70 only from the joint 80 via the inner diameter portion 42 or the deck portion 44a. That is, the bracket 70 is not subjected to repeated loads directly from the joint 80. Therefore, the tower support structure 60 can improve the fatigue life of the bracket 70.

[0064] The edge portion 75 has a curved portion 75a that curves in a direction away from the joint 80. Therefore, the tower support structure 60 having the bracket 70 can improve the fatigue life of the column portion 40a.

[0065] The cutout portion 75c surrounded by the edge portion 75 extends further toward the corner portion 76 than the diagonal line 70d. Therefore, the tower support structure 60 having the bracket 70 can further improve the fatigue life of the column portion 40a.

[0066] As described above, the embodiments of the present disclosure have been described, but the present disclosure is not limited to the above embodiments, and various modifications, changes, and improvements are possible within the scope of the technical idea of ​​the present disclosure.

[0067] For example, the floating structure 30 is used in an offshore wind power generation facility 10. However, the floating structure according to the present disclosure may be used in floating facilities other than offshore wind power generation facilities. The floating structure according to the present disclosure may be used in, for example, a floating airport, a floating production storage and offloading system (FPSO), or a megafloat.

[0068] The bracket 70 is intended to be used in the floating structure 30 of the offshore wind power generation facility 10. However, the bracket that joins the deck portion and the inner diameter portion of the column according to the present disclosure may also be used in floating structures other than offshore wind power generation facilities.

[0069] The joint 80 is formed by machining a hollow cylindrical joint material 80S. However, the forged material according to the present disclosure is not limited to a hollow cylindrical shape. The forged material according to the present disclosure may be a solid columnar shape or may have a cross section substantially similar to the cross-sectional shape of the joint 80.

[0070] The first connecting portion 86 has a rounded corner 86a. However, the first connecting portion according to the present disclosure does not need to have the rounded corner 86a as long as it continuously connects the outer peripheral surface 82b and the end faces 84a and 84b. For example, the first connecting portion according to the present disclosure may have a curved surface that forms an elliptical arc in cross-section instead of the rounded corner 86a. Furthermore, as shown in FIG. 13 , the first connecting portion according to the present disclosure may have a first connecting portion 286 that has an inclined surface 286a and curved surfaces 286b and 286c instead of the rounded corner 86a. The inclined surface 286a is a surface that is inclined with respect to the outer peripheral surface 82b and the end face 84a or 84b and overlaps with an imaginary line that intersects the outer peripheral surface 82b and the end face 84a or 84b in cross-section. The curved surface 286b is a curved surface that continuously connects the outer peripheral surface 82b and the inclined surface 286b. The curved surface 286c is a curved surface that continuously connects the end surface 84a or the end surface 84b and the inclined surface 286b.

[0071] The floating structure 30 of the offshore wind power generation facility 10 has a tower support structure 60 having a joint 80. However, the floating structure 30 of the offshore wind power generation facility 10 according to the present disclosure may have a tower support structure 360, which will be described below, as shown in Fig. 14. When describing the tower support structure 360, when parts and the like similar to those of the tower support structure 60 are used, the symbols and names of those parts and the like will be used as they are.

[0072] The tower support structure 360 ​​has a column portion 340a and a joint 380 instead of the column portion 40a and the joint 80 of the tower support structure 60. The column portion 340a has an inner diameter portion 342 and a bracket 370 instead of the inner diameter portion 42 and the bracket 70 of the column portion 40a. The inner diameter portion 342 is a hollow cylinder arranged coaxially with the main body portion 52 (not shown in FIG. 14 ) and the base portion 54 of the tower structure 50. The diameter of the cylindrical portion 382 is larger than the diameters of the main body portion 52 and the base portion 54. That is, the cylindrical portion 382 is arranged radially outward from the main body portion 52 and the base portion 54 in a plan view. The cylindrical portion 382 does not overlap with the main body portion 52 and the base portion 54 in a plan view. As shown in FIG. 14 , the bracket 370 is a plate-like member that is welded to the outer circumferential surface of the inner diameter portion 342 and the lower surface of the deck portion 44a. The bracket 370 is further joined by welding to a second connecting portion 389 of the joint 380, which will be described later. The bracket 370 may be further joined by welding to the cylindrical portion 382 and / or the protruding portion 84 of the joint 380. Note that the column portion 340a is provided with a plurality of brackets 370, similar to the plurality of brackets 70 of the column portion 40a (see FIG. 3). The brackets 370 will be described in detail below.

[0073] The joint 380 is disposed between the base 54, the inner diameter portion 342, and the deck portion 44a and joined by welding. As shown in Figures 15 and 16, the joint 380 has a cylindrical portion 382 instead of the cylindrical portion 82 of the joint 80. The joint 380 has a second connecting portion 389 instead of the first connecting portion 86 on the vertically lower side of the joint 80. The joint 380 also has a first connecting portion 386 instead of the first connecting portion 86 on the vertically upper side of the joint 80. In other words, the joint 380 has a single first connecting portion 386.

[0074] As shown in FIG. 15 , the cylindrical portion 382 has a hollow cylindrical shape extending along an imaginary axis C (not shown in FIG. 15 ). The cylindrical portion 382 has a tower side portion 387, a column inner portion 388, and a boundary portion 382c. The boundary portion 382c is an annular boundary line that imaginarily separates the tower side portion 387 from the column inner portion 388. It is preferable that the position of the boundary portion 382c in the Z direction overlaps with the protrusion 84.

[0075] The tower side portion 387 is located vertically above the column inner portion 388 in the cylindrical portion 382. The tower side portion 387 is an example of an upper cylindrical portion. The tower side portion 387 has a hollow truncated cone shape extending along the imaginary axis C. The tower side portion 387 is concentric with the base portion 54 of the tower structure 50. The diameter of the tower side portion 387 decreases as it moves from the boundary portion 382c to the +Z side. As shown in FIG. 14 , the +Z side end of the tower side portion 387 is joined by welding to the −Z side end of the base portion 54. The diameter R1 of the inner circumferential surface of the +Z side end of the tower side portion 387 is within a range of 7 m to 12.9 m.

[0076] As shown in FIG. 15 , the column inner portion 388 is located vertically below the tower side portion 387 in the cylindrical portion 382. The column inner portion 388 is an example of a lower cylindrical portion. The column inner portion 388 has a hollow cylindrical shape extending uniformly along the imaginary axis C. The column inner portion 388 is concentric with the tower side portion 387 and the inner diameter portion 342 of the column portion 340a. The column inner portion 388 extends from the boundary portion 382c to the −Z side along the imaginary axis C. The diameter R2 of the inner circumferential surface of the column inner portion 388 is larger than the diameter R1 of the inner circumferential surface of the +Z side end of the tower side portion 387. In other words, the diameter of the vertical lower end of the cylindrical portion 382 is larger than the diameter of the vertical upper end of the cylindrical portion 382. The −Z side end of the column inner portion 388 is joined by welding to the +Z side end of the inner diameter portion 342, as shown in FIG. 14 . The diameter R2 of the inner peripheral surface of the column inside portion 388 is preferably the same as the diameter of the inner peripheral surface of the inner diameter portion 342. In other words, the diameter of the vertical lower end of the cylindrical portion 382 is preferably the same as the diameter of the inner diameter portion 342.

[0077] 15 , the first connection portion 386 is a corner portion of the joint 380 located between the tower side portion 387 and the protruding portion 84. The first connection portion 386 connects the outer peripheral surface of the tower side portion 387 and the end face 84a over the entire circumferential direction. In other words, the first connection portion 386 is provided vertically above the protruding portion 84. The first connection portion 86 is annular in shape and concentric with the cylindrical portion 382 in a plan view. The first connection portion 386 has a corner R surface 386a.

[0078] The corner R surface 386a is a curved surface that defines the outer shape of the first connecting portion 386. In the cross-sectional view shown in Fig. 15 , the corner R surface 386a has an arc shape with a radius RC that continuously connects the outer circumferential surface of the tower side portion 387 and the end face 84. In a plan view, the corner R surface 386a has an annular shape that is concentric with the cylindrical portion 382.

[0079] The second connecting portion 389 is formed between the column inner portion 388 and the protruding portion 84. That is, the second connecting portion 389 is provided vertically below the protruding portion 84. The second connecting portion 389 connects the column inner portion 388 and the protruding portion 84. The second connecting portion 389 protrudes radially outward from the column inner portion 388. The length by which the second connecting portion 389 protrudes radially outward from the column inner portion 388 is shorter than the length by which the protruding portion 84 protrudes radially outward from the column inner portion 388. The second connecting portion 389 protrudes toward the -Z side from the protruding portion 84. In the cross-sectional view shown in FIG. 15 , the second connecting portion 389 has a rectangular cross section protruding from the column inner portion 388 and the protruding portion 84. As shown in FIG. 16 , the second connecting portion 389 extends in the circumferential direction. That is, the second connecting portion 389 is a hollow cylinder concentric with the cylindrical portion 382 in a plan view and protrudes from the column inner portion 388 and the protruding portion 84. The second connecting portion 389 connects the outer peripheral surface of the column inner portion 388 to the end face 84b over the entire circumferential direction. The second connecting portion 389 has a first protruding surface 389a and a second protruding surface 389b. The first protruding surface 389a faces the -Z direction. The protruding length of the first protruding surface 389a from the end face 84b is preferably longer than the protruding length of the first connecting portion 386 from the end face 84a. That is, the protruding amount of the second connecting portion 389 from the protruding portion 84 is preferably greater than the protruding amount of the first connecting portion 386 from the protruding portion 84. The second protruding surface 389b is a cylindrical surface facing radially outward. The protruding length of the second protruding surface 389b from the outer circumferential surface of the column inside portion 388 is preferably longer than the protruding length of the first connecting portion 386 from the outer circumferential surface of the tower side surface. In other words, the protruding amount of the second connecting portion 389 from the cylindrical portion 382 is preferably greater than the protruding amount of the first connecting portion 386 from the cylindrical portion 382.

[0080] The cylindrical portion 382, ​​the protruding portion 84, the first connecting portion 386, and the second connecting portion 389 are formed by machining the joint material 80S shown in Fig. 8. That is, the cylindrical portion 382, ​​the protruding portion 84, the first connecting portion 386, and the second connecting portion 389 are integrally formed from the same joint material 80S.

[0081] As shown in FIG. 14 , the bracket 370 has a frame shape that follows the inner diameter portion 342 and the deck portion 44a when viewed in the circumferential direction. The bracket 370 has joints 371 and 372 instead of the joints 71 and 72 of the bracket 70. The bracket 370 has an inner edge portion 370a and a joint 379. The bracket 370 does not have the edge portion 75. As shown in FIG. 14 , the joint 371 is joined to the outer peripheral surface of the inner diameter portion 342 by welding. The joint 371 may be joined to the column inner portion 388 of the joint 380 by welding. The joint 372 is joined to the lower surface of the deck portion 44a by welding. The joint 372 may be joined to the protrusion 84 of the joint 380 by welding. The joint portion 379 connects the end of the joint portion 371 on the joint 380 side to the end of the joint portion 372 on the joint 380 side. As shown in FIG. 14 , the joint portion 379 has a shape corresponding to the cross-sectional shape of the second connecting portion 389 of the joint 380. The joint portion 379 is joined by welding to the protruding surfaces 389a, 389b of the second connecting portion 389. The inner edge portion 370a is the inner peripheral portion of the bracket 370, which is frame-shaped when viewed from the circumferential direction. The inner edge portion 370a is generally rectangular when viewed from the circumferential direction. The corners of the generally rectangular inner edge portion 370a are preferably rounded and curved. The inner edge portion 370a defines an opening 370b. The opening 370b penetrates the plate surface of the bracket 370 in the plate thickness direction. The aperture 370b is preferably provided so as to be sandwiched between the joint 379 and the corner 76. The aperture 370b is further preferably provided so as to be sandwiched between the corner 77 and the corner 78.

[0082] Next, the operation and effect of the joint 380 will be described. The diameter of the vertical lower end of the cylindrical portion 382 is larger than the diameter of the vertical upper end of the cylindrical portion 382. Therefore, with the joint 380, even when the joining end (inner diameter portion 371) of the column portion 340a to the joint 380 has a larger diameter than the base 54 of the tower structure 50, the joint 380 can be joined to the column portion 340a.

[0083] The joint 380 has a second connecting portion 389. Therefore, the joint 380 can improve the strength and fatigue life of the joint 380. The second connecting portion 389 has protruding surfaces 389 a and 389 b. Therefore, the joint 380 can be easily joined to the bracket 370.

[0084] The bracket 370 is joined to the joint 380. Therefore, according to the tower support structure 360, the fatigue life of the joint 380 in the tower support structure 360 ​​can be improved.

[0085] The cylindrical portion 82 of the joint 80 has a hollow cylindrical shape that extends substantially uniformly along the imaginary axis C. However, the cylindrical portion of a joint according to the present disclosure may have a hollow cylindrical shape that does not have a uniform diameter. For example, the cylindrical portion 82 of the joint 80 may have a hollow cylindrical shape with different diameters at both ends in the extension direction, like the cylindrical portion 382 of the joint 380 shown in Figures 14 and 15. The cylindrical portion of a joint according to the present disclosure may have a hollow truncated cone shape that extends along the imaginary axis C.

[0086] The second connection portion 389 of the joint 380 extends in the circumferential direction. However, the second connection portion according to the present disclosure does not have to extend in the circumferential direction. The second connection portion according to the present disclosure may be a wall-like portion facing in the circumferential direction, such as the second connection portion 489 shown in FIG. 17 , provided between the cylindrical portion 82 and the protruding portion 84a. The second connection portion 489 is joined to the bracket 370. In the joint 380, a plurality of second connection portions 489 are provided to correspond to the plurality of brackets 370 provided on the column portion 340a. In other words, the plurality of second connection portions 489 are provided so as to surround the cylindrical portion 82.

[0087] 10: Offshore wind power generation facility 20: Wind power generation device 30: Floating structure 31a: Brace 31b: Brace 31c: Brace 40a: Column section 40b: Column section 40c: Column section 42: Inner diameter section 44a: Deck section 50: Tower structure 52: Main body section 52a: Flange section 54: Base section 60: Tower support structure 70: Bracket 70d: Diagonal line 71: Joint section 72: Joint section 73: Edge section 74: Edge section 75: Edge section 75a: Curved section 75c: Notch section 76: Corner section 77: Corner section 78: Corner section 80: Joint 82: Cylindrical section 82a: Inner peripheral surface 82b: Outer circumferential surface 84: Protrusion 84a: End surface 84b: End surface 86: First connecting portion 86a: Corner R surface 80S: Joint material (forged material) 340a: Column portion 360: Tower support structure 370: Bracket 380: Joint 382: Cylindrical portion 388: First connecting portion 389: Second connecting portion C: Central axis B: Water bottom S: Water surface

Claims

1. A joint for joining a base of a tower structure to be installed on the ocean and a column part of a floating structure, comprising: a cylindrical portion having an inner circumferential surface and an outer circumferential surface; a protruding portion concentric with said cylindrical portion and forming an annular shape protruding radially from said outer circumferential surface, said protruding portion having an end face facing in the axial direction; and a first connecting portion between said cylindrical portion and said protruding portion forming an annular shape concentric with said cylindrical portion, said first connecting portion continuously connecting said outer circumferential surface and said end face, wherein said cylindrical portion, said protruding portion and said first connecting portion are integrally formed from the same forged material.

2. The joint according to claim 1, wherein the first connection portion has a corner R surface.

3. A joint as claimed in claim 1 or 2, wherein the cylindrical portion extends in a vertical direction, and the diameter of the vertical lower end of the cylindrical portion is larger than the diameter of the vertical upper end of the cylindrical portion.

4. A joint as claimed in any one of claims 1 to 3, wherein the cylindrical portion extends in the vertical direction, the first connection portion is provided vertically above the protruding portion, and a cylindrical second connection portion is provided vertically below the protruding portion, connecting the cylindrical portion and the protruding portion, the second connection portion protruding greater than the first connection portion with respect to the cylindrical portion and the protruding portion, and the cylindrical portion, the protruding portion, the first connection portion, and the second connection portion are integrally formed from the same forged material.

5. A joint according to any one of claims 1 to 4, wherein the tower structure has a diameter of 7m or more.

6. A joint as claimed in any one of claims 1 to 5, wherein the inner circumferential surface has a diameter of 7 mm or more.

7. A tower support structure for supporting a tower structure provided on a floating structure, comprising: a base of the tower structure; a first column portion having an inner diameter portion concentric with the tower structure and a deck portion provided radially outward from the inner diameter portion and facing the axial direction; and a joint described in any one of claims 1 to 6 that joins the base, the inner diameter portion, and the deck portion.

8. The tower support structure according to claim 7, further comprising a bracket connecting said inner diameter portion and said deck portion.

9. A tower support structure as described in claim 8, wherein the bracket has: a first joint portion that joins with the inner diameter portion; a second joint portion that joins with the deck portion; and an edge portion that connects the joint side end of the first joint portion and the joint side end of the second joint portion; and the first joint portion, the second joint portion, and the edge portion are not joined to the joint.

10. A tower support structure as claimed in claim 9, wherein said edge has a curvature that curves away from said joint.

11. A tower support structure as described in claim 9 or 10, wherein the bracket further has: a first edge portion facing the first joint across the second joint; a second edge portion facing the second joint across the first joint; a first corner portion connecting the first edge portion and the second edge portion; a second corner portion connecting the first edge portion and the second joint; a third corner portion connecting the second edge portion and the first joint; and a cutout portion surrounded by the edges, wherein the cutout portion extends further toward the first corner than a diagonal line between the second corner portion and the third corner portion.

12. The tower support structure of claim 8, wherein said bracket further joins with said joint.

13. A floating structure comprising: a tower support structure as defined in any one of claims 7 to 12; a second column section; a third column section; a first brace provided between the first column section and the second column section; a second brace provided between the second column section and the third column section; a third brace provided between the third column section and the first column section; and a tower structure provided on the first column section.

14. An offshore wind power generation facility comprising: a floating structure as claimed in claim 13; and a wind power generation device mounted on the tower structure.

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