How to design an offshore wind system

Abstract

To provide a jacket structure and an offshore wind system having sufficient ultimate strength at low cost.SOLUTION: A jacket structure 10 that includes a transition piece 11 that supports an offshore wind turbine 200, a plurality of legs 12 that supports the transition piece 11, a plurality of braces 13 that connect the plurality of legs 12, and a plurality of stakes 15. A part of the steel material of the jacket structure 10 is characterized by being SA440 or SM570.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a jacket structure and an offshore wind system. [Background technology]

[0002] 2. Description of the Related Art In order to install wind turbines and other devices used for wind power generation offshore, a jacket structure made of steel pipes is sometimes used. Patent Document 1 discloses a jacket structure in which a reinforcing portion is provided inside a main member that also serves as a pile guide as a countermeasure against earthquakes. Patent Document 2 discloses a joint structure that reduces the number of welded points between a steel pipe pile and an outer steel pipe as a measure against repeated loads caused by vibrations of a wind turbine. Patent Document 3 discloses a structure in which, to enable rational design of the jacket and piles, a pile with a shear key that protrudes from the water bottom to a required height or more is inserted into the lower part of a leg whose inner diameter is larger than the pile diameter, and the joint is joined by filling a specified length of the inner periphery of the leg and the outer periphery of the pile with grout material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-11363 A [Patent Document 2] International Publication No. 2012 / 118186 [Patent Document 3] JP 2003-221816 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the jacket structure, it is sometimes required to improve the ultimate strength of a part of it.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a jacket structure and an offshore wind power system that are low cost and have sufficient ultimate strength. [Means for solving the problem]

[0006] <1> The jacket structure according to aspect 1 of the present invention is a jacket structure comprising a transition piece supporting an offshore wind turbine, a plurality of legs supporting the transition piece, a plurality of braces connecting the plurality of legs, and a plurality of piles, wherein a portion of the steel material of the jacket structure is SA440 or SM570.

[0007] According to the present invention, some of the steel materials in the jacket structure are SA440 or SM570. Here, as a result of a structural analysis in the design process of the jacket structure, it may become clear that it is necessary to improve the ultimate strength of some part of the jacket structure. In this case, if a measure is taken to change the shape of the jacket structure, for example by changing the plate thickness of the steel materials constituting the jacket structure, the rigidity of the part whose shape has been changed will change. For this reason, when changing the shape of the jacket structure, it is necessary to perform a structural analysis of the jacket structure and the offshore wind turbine again. However, structural analysis of the jacket structure takes a long time (for example, several months), and therefore measures to change the shape of the jacket structure cannot be easily taken.

[0008] Among the steel materials used in the construction of the jacket structure, SA440 and SM570 are steel materials with a relatively high yield stress. Steel materials with a high yield stress, including SA440 and SM570, are characterized by, for example, being relatively expensive and taking a long time to procure.

[0009] In contrast, by using SA440 or SM570 as the steel material for a portion of the jacket structure, for example, SA440 or SM570, which has a large yield stress, can be used only in the portion of the jacket structure that needs to have improved ultimate strength. Therefore, the ultimate strength of any portion of the jacket structure can be improved without changing the shape of the jacket structure. Therefore, the jacket structure can be designed efficiently.

[0010] Furthermore, by limiting the portions in which SA440 or SM570 is used, it is possible to efficiently use steel materials having the above-mentioned characteristics and high yield stress. Therefore, for example, it is possible to prevent the cost of the jacket structure from increasing more than necessary. For example, it is possible to prevent the time required for procuring steel materials from becoming longer.

[0011] <2> An offshore wind system according to a second aspect of the present invention is an offshore wind system comprising a plurality of jacket structures, each of which is provided in the same wind farm or sea area and each of which supports an offshore wind turbine, wherein each of the plurality of jacket structures includes a transition piece supporting the offshore wind turbine, a plurality of legs supporting the transition piece, a plurality of braces connecting the plurality of legs, and a plurality of piles, each of the plurality of jacket structures belonging to a first group or a second group, and a portion of the steel material of each of the plurality of jacket structures belonging to the first group is common and is SA440 or SM570.

[0012] According to the present invention, each of the multiple jacket structures belongs to a first group or a second group. A group refers to a collection of jacket structures that have something in common. This allows the multiple jacket structures to be classified into groups according to characteristics such as water depth and ground hardness of the location where the jacket structures are installed. A part of the steel material of each of the multiple jacket structures belonging to the first group is common and is SA440 or SM570. This allows the efficient use of steel material with a large yield stress. By making the structure of each of the multiple jacket structures common, the design of the multiple jacket structures can be made more efficient.

[0013] <3> An offshore wind system according to aspect 3 of the present invention is characterized in that, in the offshore wind system according to aspect 2, the transition pieces of each of the plurality of jacket structures belonging to the first group include an upper plate and a center pipe which is a cylindrical member supporting the tower of the offshore wind turbine, and the portion includes an intersection between the upper plate and the center pipe.

[0014] According to the present invention, a part of the jacket structure using SA440 or SM570 includes the intersection between the upper plate of the transition piece and the center pipe. The intersection between the upper plate and the center pipe is a location where stress is likely to concentrate, and therefore requires high ultimate strength. By efficiently using SA440 or SM570, which has a high yield stress, in this location, the jacket structure can be designed efficiently while suppressing increases in costs and extensions in the period required for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures.

[0015] <4> An offshore wind system according to aspect 4 of the present invention is characterized in that, in the offshore wind system according to aspect 2 or aspect 3, each of the plurality of jacket structures belonging to the first group includes a connecting member connecting the plurality of legs and the plurality of piles, the connecting member including an upper flange, and the portion including an intersection of the upper flange and one of the plurality of legs.

[0016] According to the present invention, a portion of the jacket structure using SA440 or SM570 includes an intersection between the upper flange of the connection member and one of the multiple legs. The intersection between the upper flange and the leg is a location where stress is likely to concentrate, and therefore requires high ultimate strength. By efficiently using SA440 or SM570, which has a high yield stress, in this location, the jacket structure can be designed efficiently while suppressing increases in costs and extensions in the period required for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures.

[0017] <5> An offshore wind system according to a fifth aspect of the present invention is the offshore wind system according to any one of the second to fourth aspects, characterized in that the portion includes the plurality of braces.

[0018] According to the present invention, a part of the jacket structure using SA440 or SM570 includes multiple braces. The brace has a function of reinforcing the jacket structure by connecting multiple legs, and therefore is required to have high ultimate strength. By efficiently using SA440 or SM570, which has a high yield stress, in this part, the jacket structure can be designed efficiently while suppressing increases in costs and extensions in the period for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures.

[0019] <6> An offshore wind system according to aspect 6 of the present invention is an offshore wind system according to any one of aspects 2 to 5, characterized in that the plurality of braces include a first brace and a second brace, and the portion includes an intersection between the first brace and the second brace.

[0020] According to this invention, among the jacket structures, a part using SA440 or SM570 includes an intersection between the first brace and the second brace. The intersection between the first brace and the second brace is a part where stress is likely to concentrate due to the load transmitted from the leg, and therefore high ultimate strength is required. By efficiently using SA440 or SM570, which has a large yield stress, in this part, it is possible to efficiently design the jacket structure while suppressing increases in costs and extensions in the period for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures.

[0021] <7> An offshore wind system according to aspect 7 of the present invention is an offshore wind system according to any one of aspects 2 to 6, characterized in that the plurality of braces include a first brace and a second brace, and the portion includes a portion of the first brace and the second brace that does not include an intersection between the first brace and the second brace.

[0022] According to this invention, the part of the jacket structure using SA440 or SM570 includes the part of the first brace and the second brace that does not include the intersection of the first brace and the second brace. A large load is applied to the part of the first brace and the second brace that does not include the intersection of the first brace and the second brace through the legs, so high ultimate strength is required. By efficiently using SA440 or SM570, which has a large yield stress, in this part, it is possible to efficiently design the jacket structure while suppressing increases in costs and lengthening of the material procurement period. Furthermore, it is possible to easily standardize the structure of multiple jacket structures.

[0023] <8> An offshore wind system according to aspect 8 of the present invention is an offshore wind system according to any one of aspects 2 to 7, characterized in that the portion includes ends of the multiple braces.

[0024] According to the present invention, a part of the jacket structure using SA440 or SM570 includes the ends of multiple braces. For example, legs are connected to the ends of the braces. Therefore, the ends of the braces are required to have high ultimate strength because they are prone to stress concentration due to the load transmitted from the legs. By efficiently using SA440 or SM570, which have a large yield stress, in these parts, the jacket structure can be designed efficiently while suppressing increases in costs and extensions in the period for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures.

[0025] <9> An offshore wind power system according to a ninth aspect of the present invention is the offshore wind power system according to any one of the second to eighth aspects, characterized in that the portion includes the plurality of legs.

[0026] According to the present invention, a part of the jacket structure using SA440 or SM570 includes multiple legs. The legs are required to have high ultimate strength because they are subjected to a large load transmitted from the offshore wind turbine via the transition piece. By efficiently using SA440 or SM570, which have a high yield stress, in this part, the jacket structure can be designed efficiently while suppressing increases in costs and extensions in the period required for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures.

[0027] <10> An offshore wind system according to aspect 10 of the present invention is characterized in that, in the offshore wind system according to any one of aspects 2 to 9, the portion includes a portion of the plurality of legs that includes an intersection between the plurality of legs and the plurality of braces.

[0028] According to the present invention, the part of the jacket structure using SA440 or SM570 includes a part of multiple legs including intersections between multiple legs and multiple braces. The intersections between the legs and braces are areas where stress is likely to concentrate due to the load transmitted from the legs, and therefore require high ultimate strength. By efficiently using SA440 or SM570, which has a large yield stress, in these areas, the jacket structure can be designed efficiently while suppressing increases in costs and extensions in the period required for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures.

[0029] <11> An offshore wind system according to aspect 11 of the present invention is an offshore wind system according to any one of aspects 2 to 10, characterized in that the portion includes a portion of the plurality of legs that does not include intersections between the plurality of legs and the plurality of braces.

[0030] According to the present invention, the part of the jacket structure using SA440 or SM570 includes a part of multiple legs that does not include intersections between the multiple legs and multiple braces. The part that does not include intersections between the legs and braces is required to have high ultimate strength because a large load transmitted from the offshore wind turbine via the transition piece is applied to the part. By efficiently using SA440 or SM570, which has a large yield stress, in this part, the jacket structure can be designed efficiently while suppressing increases in costs and extensions in the period for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures. Effect of the Invention

[0031] According to the present invention, it is possible to provide a jacket structure and an offshore wind power system that have sufficient ultimate strength at low cost. [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a perspective view of an entire wind farm. [Diagram 2]FIG. [Diagram 3] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] An offshore wind power system 100 and a jacket structure 10 according to one embodiment of the present invention will be described below with reference to the drawings. As shown in Fig. 1, the offshore wind power system 100 includes a plurality of jacket structures 10. The plurality of jacket structures 10 are each provided in the same wind farm or sea area, and each support an offshore wind turbine 200. For example, about 25 offshore wind turbines 200 are provided in one offshore wind power system 100. Note that a wind farm (offshore wind farm) refers to, for example, a plurality of offshore wind power systems 100 arranged on the sea.

[0034] (Configuration of jacket structure 10) As shown in FIG. 2, the jacket structure 10 includes a transition piece 11, a leg 12, a brace 13, a connecting member 14, and a pile 15. The transition piece 11 supports the offshore wind turbine 200. The transition piece 11 includes an upper plate 11a, a center pipe 11b, a lower plate 11c, and a reinforcing plate 11d.

[0035] The upper plate 11a is disposed in a horizontal direction above the transition piece 11. Hereinafter, when referring to the upper plate 11a, it may be simply referred to as the upper end of the transition piece 11. In this embodiment, the horizontal direction is a direction parallel to the sea surface on which the offshore wind turbine 200 is disposed. As shown in Fig. 3, the upper plate 11a is cross-shaped, and a center pipe 11b is disposed in the center.

[0036] The center pipe 11b is a cylindrical member that supports the tower of the offshore wind turbine 200. As shown in Figs. 2 and 3, the center pipe 11b is disposed in the center of the transition piece 11. The center pipe 11b is supported by the upper plate 11a, the lower plate 11c, and the reinforcing plate 11d. In this embodiment, the offshore wind turbine 200 is connected to the center pipe 11b. In this way, the offshore wind turbine 200 is supported by the transition piece 11. The center pipe 11b is fixed to the upper plate 11a, the lower plate 11c, and the reinforcing plate 11d by, for example, welding.

[0037] The lower plate 11c is disposed horizontally at the lower end of the transition piece 11. Hereinafter, when referring to the lower plate 11c, it may be simply referred to as the lower end of the transition piece 11. As shown in Fig. 3, the lower plate 11c is cross-shaped like the upper plate 11a, and includes a center pipe 11b in the center. This allows the transition piece 11 to support the center pipe 11b at two points, above and below.

[0038] The reinforcing plate 11d is a member that reinforces the spaces between the upper plate 11a, the lower plate 11c, the center pipe 11b, and the legs 12 described below. As shown in FIG. 2, the reinforcing plate 11d is a substantially rectangular plate. The reinforcing plate 11d connects the four sides of the substantially rectangular shape to the upper plate 11a, the lower plate 11c, the center pipe 11b, and the legs 12, respectively. This reinforces the transition piece 11.

[0039] The leg 12 is a cylindrical member that supports the transition piece 11. As shown in Fig. 2, the upper end of the leg 12 is connected to the transition piece 11. The lower end of the leg 12 is connected to a pile 15 via a connection member 14. A plurality of legs 12 are provided in the jacket structure 10. In the present embodiment, for example, four legs 12 are provided in the jacket structure 10.

[0040] The brace 13 is a cylindrical member that connects multiple legs 12. Specifically, as shown in Fig. 2, the brace 13 connects adjacent legs 12 to each other in a circumferential direction about an axis extending in the vertical direction of the jacket structure 10. This allows the brace 13 to have a function of reinforcing the jacket structure 10. A plurality of braces 13 are provided between the legs 12.

[0041] The brace 13 includes a first brace 13a and a second brace 13b. The brace 13 forms an X-shape with the first brace 13a and the second brace 13b. At this time, the intersection of the first brace 13a and the second brace 13b has the following shape. That is, as shown in FIG. 2, the end of the second brace 13b contacts the side surface of the first brace 13a. In other words, the first brace 13a is a so-called through member, and the second brace 13b is in a state of being divided by the first brace 13a.

[0042] Hereinafter, the side surface of the first brace 13a to which the end of the second brace 13b is connected is referred to as the brace can. The end of the second brace 13b connected to the first brace 13a is referred to as the brace stub. In order to meet the required fatigue strength in the brace 13, it is preferable that the plate thickness of the brace can and the brace stub is thicker than, for example, portions other than the brace can and the brace stub. In this embodiment, the plate thickness of the brace can and the brace stub are equal.

[0043] Hereinafter, when there is no need to distinguish between the first brace 13a and the second brace 13b, they will be referred to as the brace 13. The X-shape formed by the brace 13 is provided, for example, in two stages in the vertical direction in the jacket structure 10. However, the X-shape may be provided in only one stage in the vertical direction in the jacket structure 10, or may be provided in three or more stages.

[0044] The connecting member 14 connects a plurality of legs 12 and a plurality of piles 15. In other words, the connecting member 14 connects one of the plurality of legs 12 provided in the jacket structure 10 and a pile 15 corresponding to one of the legs 12. In the present embodiment, as described above, four legs 12 are provided. Therefore, four connecting members 14 are provided corresponding to the number of legs 12. As shown in FIG. 2, the connecting member 14 includes an upper flange 14a, a lower flange 14b, a web 14c, and a sleeve 14d.

[0045] The upper flange 14a is a plate-like member provided on the upper side of the connecting member 14. The upper flange 14a is provided, for example, substantially horizontally. The lower flange 14b is a plate-like member provided on the lower side of the connecting member 14. The lower flange 14b is provided, for example, substantially horizontally. That is, the lower flange 14b may be provided horizontally or may be provided at an angle of 45° or less with respect to the horizontal direction. The upper flange 14a and the lower flange 14b are each provided with a leg through-hole H1 through which the leg 12 is inserted and a sleeve through-hole H2 through which the sleeve 14d passes. Thereby, the leg 12 and the sleeve 14d are connected by the upper flange 14a and the lower flange 14b. Note that the leg through-hole H1 may be provided only in the upper flange 14a or may be provided in both the upper flange 14a and the lower flange 14b as described above.

[0046] The web 14c is a plate-like member provided between the upper flange 14a and the lower flange 14b. The web 14c is provided, for example, vertically. Thereby, the upper flange 14a and the lower flange 14b are reinforced. Both ends of the web 14c in the horizontal direction are arranged, for example, along the leg 12 or the sleeve 14d.

[0047] The sleeve 14d is a cylindrical member disposed along the up-down direction. The pile 15 is inserted into the sleeve 14d. As described above, the leg 12 and the sleeve 14d are connected by the upper flange 14a and the lower flange 14b. Therefore, the leg 12 and the pile 15 are connected by inserting the pile 15 into the sleeve 14d. In this embodiment, for example, two sleeves 14d are provided in one connection member 14.

[0048] As shown in Fig. 2, the piles 15 are driven into the ground of the wind farm or sea area where the offshore wind power system 100 is provided. The piles 15 are, for example, cylindrical. A plurality of piles 15 are provided in one jacket structure 10. In this embodiment, for example, two piles 15 are provided for one leg 12. The upper end of the pile 15 is inserted into the sleeve 14d of the connection member 14. As a result, the pile 15 is connected to the leg 12. In this way, the jacket structure 10 is placed offshore.

[0049] (Regarding the steel material constituting the jacket structure 10) In this embodiment, some of the steel materials of the jacket structure 10 are SA440 according to the product regulations of the Japan Iron and Steel Federation, or SM570 according to the JIS standard. An example of SA440 is BT-HT440 manufactured by Nippon Steel Corporation. SA440 and SM570 are steel materials with a relatively high yield stress among the steel materials used in the construction of the jacket structure 10. For example, the yield stress of SA440 is 440 N / mm 2 The yield stress of SM570 varies with the plate thickness as follows. For example, when the plate thickness of SM570 is 16 mm or less, the yield stress is 460 N / mm 2 When the plate thickness of SM570 is more than 16 mm and less than 40 mm, the yield stress is 450 N / mm 2 When the plate thickness of SM570 is more than 40 mm and less than 75 mm, the yield stress is 430 N / mm 2 When the plate thickness of SM570 is more than 75 mm and less than 100 mm, the yield stress is 420 N / mm 2That is all. These steel materials have characteristics such as being relatively expensive and taking a long time to procure them.

[0050] 2 or 3, the jacket structure 10 according to the present embodiment partially uses SA440 or SM570 in the following portions, thereby reducing the cost of the jacket structure 10 and shortening the time required for procurement. Note that, for example, SM400, SM490, SM490Y, SM520, etc. are preferably used in the portions of the jacket structure 10 where SA440 or SM570 is not used. In the following description, SA440 and SM570 are referred to as high-strength steel materials, and SM400, SM490, SM490Y, SM520, etc. are referred to as general steel materials. In this embodiment, the general steel materials refer to steel materials having a lower yield stress than high-strength steel materials, for example.

[0051] The portion of the jacket structure 10 using high-strength steel includes, for example, an intersection between the upper plate 11a and the center pipe 11b (hereinafter, referred to as the first portion P1). The first portion P1 is, for example, a region of the upper plate 11a that is located particularly on the side of the center pipe 11b. The first portion P1 includes a welded portion between the upper plate 11a and the center pipe 11b. The first portion P1 may be, for example, a region of the center pipe 11b that is located particularly near the upper plate 11a. In other words, the high-strength steel is used for at least a portion of the upper plate 11a and a portion of the center pipe 11b. For example, a load transmitted from the offshore wind turbine 200 supported by the jacket structure 10 is applied to the first part P1. It is preferable to use high-strength steel material for the first part P1 so that the first part P1 can withstand the load transmitted from the offshore wind turbine 200.

[0052] A general steel material is used for the portion of upper plate 11a other than first portion P1. The portion of upper plate 11a other than first portion P1 is a region of upper plate 11a located on the leg 12 side. The portion of upper plate 11a other than first portion P1 includes an intersection between upper plate 11a and leg 12.

[0053] 3, the high-strength steel material of the first portion P1 of the upper plate 11a and the general steel material of the portion other than the first portion P1 are joined by, for example, welding. In this way, forming the upper plate 11a by welding the high-strength steel material and the general steel material has the effect of reducing the cost and shortening the procurement period as described above, and also has the effect of reducing the area of ​​the plate-shaped high-strength steel material to be procured, for example, compared to the case where the upper plate 11a is formed from a single plate-shaped high-strength steel material.

[0054] The portion of the jacket structure 10 using high-strength steel includes an intersection (hereinafter, second portion P2) between the upper flange 14a of the connection member 14 and one of the multiple legs 12. The second portion P2 is, for example, a region of the upper flange 14a that is located particularly on the leg 12 side. The second portion P2 may be, for example, a region of the leg 12 that is located particularly on the upper flange 14a side. In other words, the high-strength steel is used for at least a portion of the upper flange 14a and a portion of the leg 12. For example, earthquake load is applied to the second part P2. It is preferable to use high-strength steel material for the second part P2 so that it can withstand the earthquake load. Note that the upper flange 14a is formed of, for example, a single steel plate. Therefore, the entire upper flange 14a may be the second part P2.

[0055] The portion of the jacket structure 10 that uses high strength steel includes a plurality of braces 13 . Specifically, the portion of the jacket structure 10 that uses high-strength steel includes, for example, an intersection between the first brace 13a and the second brace 13b (hereinafter, the third portion P3). The third portion P3 is the brace can and the brace stub. When high-strength steel is used for one of the brace can and the brace stub, it is preferable that high-strength steel is also used for the other.

[0056] Of the jacket structure 10, a portion using high-strength steel may not include, for example, an intersection between the first brace 13a and the second brace 13b. In other words, of the jacket structure 10, a portion using high-strength steel may include, for example, a portion of the first brace 13a and the second brace 13b that does not include an intersection between the first brace 13a and the second brace 13b (hereinafter, a fourth portion P4). The fourth portion P4 is a portion of the brace 13 other than the brace can and the brace stub. A portion of the jacket structure 10 using high-strength steel includes ends (hereinafter, a fifth portion P5) of the braces 13. The fifth portion P5 is, for example, a connection portion between the first brace 13a or the second brace 13b and the leg 12.

[0057] The brace 13 has a function of reinforcing the jacket structure 10 by connecting the multiple legs 12, and therefore is required to have high fatigue strength and high ultimate strength. That is, for example, a large load is continuously transmitted from the offshore wind turbine 200 via the legs 12 to the connections between the first brace 13a and the second brace 13b and the legs 12, the brace cans, and the brace stubs. Increasing the plate thickness is effective for improving fatigue strength, but using high-strength steel is effective for improving ultimate strength.

[0058] The portion of the jacket structure 10 that uses high strength steel includes a plurality of legs 12 . Specifically, the portion of the jacket structure 10 that uses high-strength steel includes, for example, a portion of the multiple legs 12 that includes intersections between the multiple legs 12 and the multiple braces 13 (hereinafter, sixth part P6). The sixth part P6 is a connection portion between the first brace 13a and the second brace 13b and the legs 12. Hereinafter, the sixth part P6 will be referred to as a leg can.

[0059] A portion of the jacket structure 10 using high-strength steel may not include, for example, intersections between the legs 12 and the braces 13. In other words, a portion of the jacket structure 10 using high-strength steel may include, for example, a portion of the legs 12 that does not include intersections between the legs 12 and the braces 13 (hereinafter, a seventh portion P7). The seventh portion P7 is a portion of the leg 12 other than the leg can. In other words, the seventh portion P7 is, for example, a portion located between the leg cans or in the vicinity of the upper flange 14a of the connection member 14.

[0060] A large load is applied to the leg 12 from the offshore wind turbine 200 via the transition piece 11, and therefore a high ultimate strength is required. The sixth part P6, which is the leg can, is a connection part with the brace 13, and therefore a large load is continuously applied to the leg 12. For this reason, the sixth part P6 is required to have high fatigue strength in addition to high ultimate strength. The seventh part P7 is also required to have high ultimate strength because a large load is applied to the seventh part P7, similar to the sixth part P6. The seventh part P7 is not required to have high fatigue strength compared to the sixth part P6. For this reason, when high-strength steel is used for both the sixth part P6 and the seventh part P7, it is preferable to deal with the fatigue strength by increasing the plate thickness of the sixth part P6.

[0061] As described above, in this embodiment, a plurality of legs 12 are provided. When high-strength steel is used in the sixth portion P6 or the seventh portion P7 of the legs 12, it is preferable that the high-strength steel is used in the same portion in all the legs 12 in order to ensure the isotropy of the entire jacket structure 10.

[0062] The portion of the jacket structure 10 that uses high-strength steel includes piles 15 . Specifically, the part of the jacket structure 10 using high strength is, for example, a region (part 8 P8) including a part where the upper end of the pile 15 protrudes from the ground where the pile 15 is driven. For example, the lower part of part 8 P8 is located inside the ground and the upper part is located underwater. Here, the part of the pile 15 located inside the ground is supported by the ground. The part of the pile 15 located in the shallow part of the ground or the part located underwater, like part 8 P8, cannot obtain the effect of support by the ground. For this reason, part 8 P8 is required to have high fatigue strength. It is preferable to use high-strength steel material for part 8 P8 to meet the above-mentioned requirements.

[0063] A part of the jacket structure 10 using high-strength steel is, for example, a region (ninth part P9) including a boundary between strata in the ground where the piles 15 are driven. For example, one of the upper and lower parts of the ninth part P9 is located in a relatively hard stratum, and the other is located in a relatively soft stratum. In this case, for example, when an earthquake occurs in the place where the piles 15 are driven, a force acts so that the hard stratum and the soft stratum are displaced horizontally. At this time, a shear force is applied to the piles 15. It is preferable to use high-strength steel in the ninth part P9 so that it can withstand the shear force.

[0064] (About the offshore wind power system 100) In this embodiment, each of the multiple jacket structures 10 included in the offshore wind power system 100 belongs to a first group G1 or a second group G2. In this embodiment, a group refers to a collection of jacket structures 10 that have something in common. The first group G1 and the second group G2 are determined, for example, by the propulsion and ground conditions of the wind farm or the sea area where the offshore wind power system 100 is installed. In the offshore wind power system 100, the jacket structures 10 belonging to the same group have the same shape. Specifically, the jacket structures 10 belonging to the same group have the same framework and cross-sectional shapes of each part. For example, some of the steel materials of the multiple jacket structures 10 belonging to the first group G1 are common and are high-strength steel materials. The yield stress of the multiple jacket structures 10 belonging to the same group is common. The yield stress of the jacket structures 10 belonging to the same group does not have to be common. In this case, the jacket structure 10 is designed according to the one having the highest required yield stress among the multiple jacket structures 10 belonging to the same group.

[0065] (Method of designing jacket structure 10) Next, a method for designing the jacket structure 10 in this embodiment will be described. First, the jacket structures 10 provided in the offshore wind power system 100 are classified into a first group G1 and a second group G2. At this time, more groups may be provided depending on the water depth and ground conditions of the wind farm or the sea area.

[0066] Next, a structural analysis is performed on the jacket structure 10 classified as described above. In the structural analysis, for example, the stress, pile axial force, and deformation occurring in each part of the jacket structure 10 are analyzed. Once the structural analysis is complete, it is determined which parts of the jacket structure 10 should use high-strength steel and which parts should use general steel. Through the above steps, the jacket structure 10 is designed.

[0067] As described above, according to the jacket structure 10 of this embodiment, some of the steel materials of the jacket structure 10 are SA440 or SM570. Here, as a result of a structural analysis in the design process of the jacket structure 10, it may be found that it is necessary to improve the ultimate strength of any part of the jacket structure 10. In this case, if a measure is taken to change the shape of the jacket structure 10, for example, by changing the plate thickness of the steel materials constituting the jacket structure 10, the rigidity of the part whose shape has been changed will change. For this reason, when changing the shape of the jacket structure 10, it is necessary to perform a structural analysis of the jacket structure 10 and the offshore wind turbine 200 again. However, structural analysis of the jacket structure 10 takes a long time (for example, about several months), and therefore measures to change the shape of the jacket structure 10 cannot be easily taken.

[0068] SA440 or SM570 is a steel material having a relatively high yield stress among the steel materials used in the construction of the jacket structure 10. Steel materials having a high yield stress, such as SA440 or SM570, are characterized in that they are relatively expensive, may take a long time to procure, and so on.

[0069] In contrast, by using SA440 or SM570 as the steel material for a portion of the jacket structure 10, for example, SA440 or SM570, which has a large yield stress, can be used only in a portion of the jacket structure 10 that needs to have an improved ultimate strength. Thus, the ultimate strength of any portion of the jacket structure 10 can be improved without changing the shape of the jacket structure 10. Thus, the jacket structure 10 can be designed efficiently.

[0070] Furthermore, by limiting the portions in which SA440 or SM570 is used, it is possible to efficiently use steel materials having the above-mentioned characteristics and high yield stress. Therefore, for example, it is possible to prevent the cost of the jacket structure 10 from increasing more than necessary. For example, it is possible to prevent the time required for procuring steel materials from becoming longer.

[0071] Each of the multiple jacket structures 10 belongs to a first group G1 or a second group G2. A group refers to a collection of jacket structures 10 that have something in common. This allows the multiple jacket structures 10 to be classified into groups according to characteristics such as water depth and ground hardness of the place where the jacket structures 10 are installed. A part of the steel material of each of the plurality of jacket structures 10 belonging to the first group G1 is common and is SA440 or SM570. Thereby, a steel material with a high yield stress can be used efficiently. By making the structures of the plurality of jacket structures 10 common, the design of the plurality of jacket structures 10 can be made efficient.

[0072] Also, a part of the jacket structure 10 that uses SA440 or SM570 includes the intersection of the upper plate 11a of the transition piece 11 and the center pipe 11b. Since the intersection of the upper plate 11a and the center pipe 11b is a site where stress concentration is likely to occur, a high ultimate strength is required. By efficiently using SA440 or SM570 with a high yield stress at this site, it is possible to efficiently design the jacket structure 10 while suppressing an increase in cost and an extension of the material procurement period. Furthermore, the standardization of the structures of the plurality of jacket structures 10 can be facilitated.

[0073] Also, a part of the jacket structure 10 that uses SA440 or SM570 includes the intersection of the upper flange 14a of the connecting member 14 and one of the plurality of legs 12. Since the intersection of the upper flange 14a and the leg 12 is a site where stress concentration is likely to occur, a high ultimate strength is required. By efficiently using SA440 or SM570 with a high yield stress at this site, it is possible to efficiently design the jacket structure 10 while suppressing an increase in cost and an extension of the material procurement period. Furthermore, the standardization of the structures of the plurality of jacket structures 10 can be facilitated.

[0074] Also, a part of the jacket structure 10 that uses SA440 or SM570 includes the plurality of braces 13. Since the braces 13 have a function of reinforcing the jacket structure 10 by connecting the plurality of legs 12, a high ultimate strength is required. By efficiently using SA440 or SM570 with a high yield stress at this site, it is possible to efficiently design the jacket structure 10 while suppressing an increase in cost and an extension of the material procurement period. Furthermore, the standardization of the structures of the plurality of jacket structures 10 can be facilitated.

[0075] Furthermore, among the jacket structures 10, a portion that uses SA440 or SM570 includes an intersection between the first brace 13a and the second brace 13b. The intersection between the first brace 13a and the second brace 13b is a portion where stress is likely to concentrate due to the load transmitted from the leg 12, and therefore requires high ultimate strength. By efficiently using SA440 or SM570, which have a large yield stress, in this portion, the jacket structure 10 can be designed efficiently while suppressing increases in costs and extensions in the period required for material procurement. Furthermore, it is possible to easily standardize the structure of a plurality of jacket structures 10.

[0076] In addition, a portion of the jacket structure 10 using SA440 or SM570 includes a portion of the first brace 13a and the second brace 13b that does not include the intersection between the first brace 13a and the second brace 13b. A large load is applied to the portion of the first brace 13a and the second brace 13b that does not include the intersection between the first brace 13a and the second brace 13b through the leg 12, so high ultimate strength is required. By efficiently using SA440 or SM570, which has a large yield stress, in this portion, the design of the jacket structure 10 can be efficiently performed while suppressing increases in costs and lengthening of the period for material procurement. Furthermore, it is possible to easily standardize the structure of a plurality of jacket structures 10.

[0077] Furthermore, among the jacket structures 10, a portion that uses SA440 or SM570 includes the ends of multiple braces 13. For example, the legs 12 are connected to the ends of the braces 13. Therefore, the ends of the braces 13 are required to have high ultimate strength because they are locations where stress is likely to concentrate due to the load transmitted from the legs 12. By efficiently using SA440 or SM570, which have a large yield stress, in these locations, the jacket structure 10 can be designed efficiently while suppressing increases in costs and extensions in the period required for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures 10.

[0078] Furthermore, among the jacket structures 10, a portion that uses SA440 or SM570 includes multiple legs 12. A large load is applied to the legs 12, which is transmitted from the offshore wind turbines 200 via the transition pieces 11, and thus high ultimate strength is required. By efficiently using SA440 or SM570, which have a large yield stress, in this portion, the jacket structure 10 can be designed efficiently while suppressing increases in costs and extensions in the period required for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures 10.

[0079] Furthermore, the portion of the jacket structure 10 that uses SA440 or SM570 includes a portion of the multiple legs 12 that includes the intersections between the multiple legs 12 and the multiple braces 13. The intersections between the legs 12 and the braces 13 are areas where stress is likely to concentrate due to the load transmitted from the legs 12, and therefore require high ultimate strength. By efficiently using SA440 or SM570, which have a large yield stress, in these areas, the jacket structure 10 can be designed efficiently while suppressing increases in costs and extensions in the period required for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures 10.

[0080] Furthermore, the portion of the jacket structure 10 that uses SA440 or SM570 includes a portion of the multiple legs 12 that does not include an intersection between the multiple legs 12 and the multiple braces 13. A large load transmitted from the offshore wind turbine 200 via the transition piece 11 is applied to the portion that does not include the intersection between the legs 12 and the braces 13, and therefore high ultimate strength is required. By efficiently using SA440 or SM570, which have a large yield stress, in this portion, the jacket structure 10 can be designed efficiently while suppressing increases in costs and extensions in the period for material procurement. Furthermore, it is possible to easily standardize the structure of multiple jacket structures 10.

[0081] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the above-mentioned second portion P2 has been described as a region including the upper flange 14a and the leg 12, but may further include the web 14c. That is, the web 14c of the connection member 14 may be made of a high-strength steel material. Furthermore, as long as some of the steel materials of the multiple jacket structures 10 belonging to the first group G1 have a common shape, they do not necessarily need to be made of a common material. In this embodiment, the jacket structure 10 has been described as an example, but the present invention is not limited thereto. For example, a monopile structure may be adopted instead of the jacket structure 10. In such a case, a portion of the monopile structure using SA440 or SM570 becomes, for example, a member of the monopile structure near the seabed surface.

[0082] In addition, within the scope of the invention, the components in the above-described embodiments may be replaced with well-known components, and the above-described modified examples may be combined as appropriate. [Explanation of symbols]

[0083] 10 Jacket structure 11 Transition Piece 11a Upper plate 11b Center pipe 11c Lower plate 11d Reinforcement plate Leg 12 13. Brace 13a First Brace 13b 2nd brace 14 Connection parts 14a Upper flange 14b Bottom flange 14c Web 14d Sleeve 15 stake 200 Offshore Wind Turbines G1 1st Group G2 2nd Group H1 leg through hole H2 Sleeve Through Hole P1 Part 1 P2 Part 2 P3 Part 3 P4 Part 4 P5 Part 5 P6 Part 6 P7 Part 7 P8 Part 8 P9 Part 9

Claims

1. A plurality of marine structures each installed in the same wind farm or sea area and each supporting an offshore wind turbine; Equipped with Each of the plurality of marine structures includes a transition piece that supports the offshore wind turbine; Each of the plurality of marine structures belongs to a first group or a second group, The first group and the second group are determined based on the water depth and ground conditions of the wind farm or the sea area, The marine structures belonging to the same group have the same shape, A method for designing an offshore wind power system, wherein a part of the steel materials of each of the plurality of marine structures belonging to the first group is common and is SA440 or SM570, A structural analysis step of performing a structural analysis of the marine structure belonging to the wind farm or the first group determined by the water depth and ground conditions of the sea area, The part is a part for which it has been determined that a high-strength steel material having a higher yield stress than a general steel material should be used as the part for which the ultimate strength of the marine structure needs to be improved when it has been found based on the results of the structural analysis that the ultimate strength of any part of the marine structure needs to be improved. A method for designing an offshore wind power system, comprising:

2. Each of the plurality of marine structures is a jacket structure including a plurality of legs supporting the transition piece, a plurality of braces connecting the plurality of legs, and a plurality of piles; The transition piece of each of the plurality of jacket structures belonging to the first group includes: An upper plate and a center pipe which is a cylindrical member supporting a tower of the offshore wind turbine; Including, the portion includes an intersection between the upper plate and the center pipe. The method for designing an offshore wind power system according to claim 1 .

3. Each of the plurality of marine structures is a jacket structure including a plurality of legs supporting the transition piece, a plurality of braces connecting the plurality of legs, and a plurality of piles; Each of the plurality of jacket structures belonging to the first group includes a connection member connecting the plurality of legs and the plurality of piles, The connecting member includes an upper flange, the portion includes an intersection of the upper flange and one of the plurality of legs. The method for designing an offshore wind power system according to claim 1 .

4. Each of the plurality of marine structures is a jacket structure including a plurality of legs supporting the transition piece, a plurality of braces connecting the plurality of legs, and a plurality of piles; the portion includes the plurality of braces, The method for designing an offshore wind power system according to claim 1 .

5. the plurality of braces includes a first brace and a second brace; The portion includes an intersection point between the first brace and the second brace. The method for designing an offshore wind power system according to claim 4.

6. the plurality of braces includes a first brace and a second brace; The portion includes a portion of the first brace and the second brace that does not include an intersection between the first brace and the second brace. The method for designing an offshore wind power system according to claim 4.

7. the portion includes ends of the plurality of braces; The method for designing an offshore wind power system according to claim 4.

8. Each of the plurality of marine structures is a jacket structure including a plurality of legs supporting the transition piece, a plurality of braces connecting the plurality of legs, and a plurality of piles; the portion includes the plurality of legs, The method for designing an offshore wind power system according to claim 1 .

9. The portion includes a portion of the plurality of legs including an intersection between the plurality of legs and the plurality of braces, The method for designing an offshore wind system according to claim 8.

10. The portion includes a portion of the plurality of legs that does not include an intersection between the plurality of legs and the plurality of braces, The method for designing an offshore wind system according to claim 8.

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