WO2024128273A1 - Structure cylindrique polygonale, procédé de conception de structure cylindrique polygonale et structure de fondation pour installation de production d'énergie éolienne océanique utilisant une structure cylindrique polygonale - Google Patents

Structure cylindrique polygonale, procédé de conception de structure cylindrique polygonale et structure de fondation pour installation de production d'énergie éolienne océanique utilisant une structure cylindrique polygonale Download PDF

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Publication number
WO2024128273A1
WO2024128273A1 PCT/JP2023/044779 JP2023044779W WO2024128273A1 WO 2024128273 A1 WO2024128273 A1 WO 2024128273A1 JP 2023044779 W JP2023044779 W JP 2023044779W WO 2024128273 A1 WO2024128273 A1 WO 2024128273A1
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polygonal
cylindrical structure
cross
corners
section
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PCT/JP2023/044779
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English (en)
Japanese (ja)
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克也 ▲廣▼▲瀬▼
和正 久積
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日本製鉄株式会社
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  • the present invention relates to a polygonal tubular structure, a design method for a polygonal tubular structure, and a foundation structure for offshore wind power generation facilities using a polygonal tubular structure.
  • Patent Document 2 a polygon is constructed by connecting flat steel plates in the circumferential direction by welding, but there is a risk of the cost increasing due to the excessive increase in the number of corners. Furthermore, in order for a polygonal structure to exhibit bending performance equivalent to that of a circle under the same cross-sectional area, it is generally thought that the outer diameter should be increased to increase the second moment of area. However, as the perimeter increases, the plate thickness becomes relatively smaller, and the local buckling strength of the plate decreases.
  • the buckling mode that determines the limit state changes from elephant foot buckling that occurs in circular members to local buckling of plates, so it is necessary to increase the number of corners of the polygon and reduce the width-thickness ratio of one side to improve the local buckling strength.
  • increasing the number of corners increases the welding line length and assembly labor, which increases costs, and there is room for improvement in this regard.
  • the present invention was made in consideration of the above-mentioned problems, and aims to provide a polygonal tubular structure that can achieve a good balance between exhibiting bending performance equivalent to that of a circular structure and reducing costs by omitting bending processes and reducing welding processes, a design method for a polygonal tubular structure, and a foundation structure for offshore wind power generation facilities that uses a polygonal tubular structure.
  • Aspect 1 of the polygonal tubular structure of the present invention is a polygonal tubular structure whose horizontal cross-sectional shape is formed with the same number of corners, and is constructed by connecting steel flat plate members by welding in the circumferential direction and the column axial direction, the cross-sectional shape is a polygonal cross-section having 6 to 24 sides, the plate thickness of the flat plate members is 40 mm or more and 250 mm or less, and the ratio of the outer diameter to the plate thickness (outer diameter/plate thickness) of the polygonal cross-section is 200 or less.
  • Aspect 1 of the design method for a polygonal tubular structure of the present invention is a design method for a polygonal tubular structure whose horizontal cross-sectional shape is formed with the same number of corners, characterized in that the method is constructed by connecting steel flat plate members by welding in the circumferential direction and the column axial direction, the cross-sectional shape is a polygonal cross-section having 6 to 24 sides, the plate thickness of the flat plate members is 40 mm or more and 250 mm or less, and the polygonal cross-section is designed so that the ratio of outer diameter to plate thickness (outer diameter/plate thickness) is 200 or less.
  • the plate thickness of the flat plate member is set to 40 mm or greater and 250 mm or less, and the ratio of the outer diameter to the plate thickness (outer diameter/plate thickness) is set to 200 or less, thereby making it possible to suppress local buckling, and to select a specification for the number of corners that has the same cross-sectional area as a circle and exhibits bending performance equivalent to that of a circle, and a polygonal tubular structure can be manufactured in which the weld line length can be shortened.
  • the present invention allows the arrangement of the flat plate members to be constructed by merely adjusting the geometry, and it is possible to omit the bending process and reduce the costly assembly and welding process. Therefore, the present invention can achieve a good balance between improving the bending performance to be equivalent to that of a circle and suppressing increases in costs. Furthermore, the present invention can provide a low-cost polygonal cylindrical structure because reinforcing members such as ribs are not required.
  • n ⁇ 6 when D/t ⁇ 80 ⁇ ...
  • D outer diameter (mm)
  • t plate thickness (mm)
  • n number of corners (natural number).
  • the minimum number of corners n that results in the same cross-sectional area as a circle and the same bending performance can be determined according to the diameter-to-thickness ratio D/t using formula (1) or (2), making it possible to manufacture a polygonal cylindrical structure with the minimum weld line length.
  • the polygonal cross section is a regular polygon.
  • the polygonal cross section is a regular polygon.
  • the cross-sectional shape approaches a circle, so as described above, it is possible to more precisely manufacture a polygonal cylindrical structure with the minimum number of corners (i.e., the minimum welding line length) that exhibits bending performance equivalent to that of a circle.
  • Aspect 1 of the foundation structure for offshore wind power generation equipment according to the present invention is characterized in that it comprises a polygonal tubular structure according to any one of aspects 1 to 3, and that the polygonal tubular structure serves as the foundation for the offshore wind power generation equipment.
  • the polygonal tubular structure, the design method for the polygonal tubular structure, and the foundation structure for offshore wind power generation facilities using the polygonal tubular structure of the present invention achieve a good balance between exhibiting bending performance equivalent to that of a circular structure and reducing costs by eliminating bending processes and reducing welding processes.
  • FIG. 2 is a perspective view showing a polygonal column according to an embodiment of the present invention.
  • 2 is a horizontal cross-sectional view of a portion of the polygonal column shown in FIG. 1 in the height direction.
  • 4 is a horizontal cross-sectional view showing a welding state between circumferentially adjacent flat plate members.
  • FIG. FIG. 1 is a diagram showing an analytical model according to an embodiment.
  • 4A to 4D are diagrams showing an example of contours of the distribution of equivalent plastic strain at maximum bending load based on the analysis results of an embodiment.
  • FIG. 13 is a diagram showing the relationship between the number of corners and the bending performance of a polygonal tubular structure according to an embodiment.
  • FIG. 1 is a diagram showing an analytical model according to an embodiment.
  • 4A to 4D are diagrams showing an example of contours of the distribution of equivalent plastic strain at maximum bending load based on the analysis results of an embodiment.
  • FIG. 13 is a diagram showing the relationship between the number of corners and the bending
  • FIG. 13 is a diagram showing the relationship between the number of corners and the diameter-to-thickness ratio that provides performance equivalent to that of a circular cylinder according to an embodiment.
  • FIG. 2 is a perspective view showing a polygonal column according to an embodiment of the present invention.
  • FIG. 2 is a perspective view showing a polygonal column according to an embodiment of the present invention.
  • FIG. 2 is a perspective view of a cylinder for explaining the structure.
  • the polygonal cylindrical structure of this embodiment is exemplified by a tower (not shown) that secures a rotor made of blades, and a foundation structure (hereinafter referred to as polygonal columnar body 1) for wind power generation equipment that supports the tower from below.
  • a tower not shown
  • polygonal columnar body 1 for wind power generation equipment that supports the tower from below.
  • the direction parallel to the central axis O is called the column axis direction
  • the direction going around the central axis O is called the circumferential direction
  • the direction perpendicular to the central axis O is called the radial direction
  • the radial direction toward the central axis O is called the inward direction
  • the direction away from the central axis O is called the outward direction.
  • the polygonal columnar body 1 is a polygonal cylindrical structure whose horizontal cross-sectional shape is formed by the same number of corners (here, an octagon).
  • the polygonal columnar body 1 is constructed by connecting steel flat plate members 10 in the circumferential and column axial directions by welding.
  • the horizontal cross-sectional shape of the polygonal columnar body 1 perpendicular to the column axial direction forms a regular polygonal cross section of a regular octagon.
  • the flat plate member 10 may be a single steel plate, or may be a steel plate constructed by welding multiple plates together in the circumferential or column axial direction.
  • the cross-sectional shape of the polygonal columnar body 1 may be a polygonal cross section having a hexagon or more and a 24-sided or less side. It is not limited to a regular polygon with equal side lengths, and it is also possible to adopt a polygon with some or all of the side lengths being different. It is also not limited to a polygonal or regular polygonal cylindrical structure with equal plate thickness in the column axis direction, and it is also possible to adopt a polygonal or regular polygon with different plate thickness in the column axis direction. For example, the plate thickness of the flat plate member 10 may become thinner from a predetermined height position in the column axis direction toward the top (the upper part of the cylindrical structure).
  • the predetermined height position may be, for example, any position above the lower end of the polygonal columnar body 1. In the portion where the plate thickness changes in this way, the plate thickness of a certain flat plate member 10 is thinner than that of another flat plate member 10 adjacent to the upper side.
  • the flat plate members 10 are not limited to being cylindrical structures of polygons or regular polygons in which the lengths in the column axis direction are all equal, and it is also possible to adopt polygons or regular polygons in which the lengths in the column axis direction of each ring body 10A are different.
  • the length of the flat plate members 10 in the column axis direction may be increased from a predetermined height position in the column axis direction toward the top (upper part of the cylindrical structure).
  • the length in the column axis direction of another flat plate member 10 adjacent to the upper side is longer than the length in the column axis direction of a certain flat plate member 10.
  • the plate thickness of the flat plate member 10 may be thin and the length in the column axis direction may be long toward the top (upper part of the cylindrical structure) in the column axis direction.
  • the plate thickness and length of the flat plate member 10 do not need to gradually change toward the top (upper part of the cylindrical structure) in the column axis direction, and may change from any height position in the column axis direction.
  • the plate thickness and length in the column axis direction of another flat plate member 10 adjacent to the upper side are thinner and longer than the plate thickness and length in the column axis direction of a certain flat plate member 10.
  • the following cases are treated as regular polygons in the present invention.
  • the dimensions of all the flat plate members 10 fall within ⁇ 2% of the average value.
  • angles with adjacent flat plate members 10 inner angles of a regular polygon, all inner angles fall within ⁇ 2% of (180 ⁇ (n ⁇ 2))/n).
  • the polygonal column 1 is a long body that is installed with the column axis direction parallel to the vertical direction, and has a cylindrical shape with a hollow interior. Devices that do not contribute to structural performance may be installed in the hollow part of the polygonal column 1.
  • the polygonal column 1 is also made to have a truncated pyramid shape (tapered shape) in which the cross-sectional shape gradually decreases only in the upper part or as it goes upward. In other words, the cross-sectional shapes at any height in the column axis direction are similar.
  • the polygonal column 1 does not have to be tapered in the column axis direction.
  • the flat plate member 10 constituting the polygonal column 1 is a thick plate member in which no curved or bent portion is formed.
  • the plate thickness t of the flat plate member 10 is 40 mm or more and 250 mm or less.
  • the polygonal cross section of the polygonal column 1 having bending performance equivalent to that of a circle is preferably set to have a ratio of the outer diameter D (mm) to the plate thickness t (mm) (outer diameter D/plate thickness t) of 200 or less. If it exceeds 440, it becomes difficult to exhibit bending performance equivalent to that of a circle even if the polygonal cross section has a 24-sided polygon.
  • 10 shows a cylinder 100 whose perimeter is the same as the perimeter of the cross section of the polygonal column 1.
  • the outer diameter D of the polygonal column 1 corresponds to a diameter D100 at the center line of a flat plate member 110 of the cylinder 100 whose perimeter is the same in cross section.
  • the number of corners n (a natural number) of the polygonal cross section of the polygonal column 1 satisfies formula (1) or formula (2).
  • n ⁇ 6 when D/t ⁇ 80 ⁇ ...
  • D outer diameter (mm)
  • t plate thickness (mm)
  • n number of corners (natural number).
  • the unit of the outer diameter D is meters (m)
  • the unit is first changed to millimeters (mm) when calculating D/t.
  • the flat plate members 10 connected in the circumferential and column axial directions are formed by connecting them with welding.
  • the symbol W in FIG. 1 indicates the welded portion (weld).
  • the weld W has a horizontal weld W1 extending along the circumferential direction and a vertical weld W2 extending along the column axial direction.
  • eight flat plate members 10 of the same shape are connected in the circumferential direction, so that the cross-sectional shape of the polygonal columnar body 1 is a regular octagon.
  • the polygonal columnar body 1 of this embodiment is formed by connecting ring bodies, each of which is made of eight flat plate members 10 connected in the circumferential direction, in one or more stages (six stages are shown in FIG. 1 ) in the column axial direction.
  • the vertical welds W2 of the ring bodies 10A connected in the column axial direction are continuous with each other in the column axial direction.
  • the horizontal welds W1 of the ring bodies 10A may be continuous with each other in the circumferential direction.
  • the horizontal welds W1 will be discontinuous in the circumferential direction, but the vertical welds W2 will be continuous in the column axis direction.
  • a plate piece (flat plate member 10) of a predetermined size is cut out from a large steel plate serving as a base material.
  • the plate piece (flat plate member 10) of a predetermined size is, for example, a plate piece having a length corresponding to the circumferential direction when the polygonal columnar body is constructed, which is 1.0 m or more and 5.0 m or less, and a length corresponding to the column axis direction, which is 2.0 m or more and 15.0 m or less.
  • the necessary number of flat plate members 10 for constructing the polygonal columnar body 1 are cut out.
  • the large steel plate serving as the base material may be used as the flat plate member 10 as it is without going through the cutting process.
  • the flat plate member 10 may be a cut plate piece or a single steel plate used without cutting, or may be a steel plate formed by welding the cut plate piece or the steel plate used without cutting in the circumferential direction or the column axis direction. In this way, when the flat plate member 10 is formed by welding a plurality of plate pieces in the circumferential direction or the column axis direction, the plate pieces adjacent to each other in the circumferential direction can be treated as the same flat plate member 10 if the angle between them in the circumferential direction is within 1.0°.
  • the flat plate members 10 are arranged, for example, on a stand (not shown).
  • two flat plate members 10 adjacent in the circumferential direction are arranged so as to butt against each other at a predetermined crossing angle.
  • the predetermined crossing angle is an angle (i.e., an interior angle of a polygon) at which the cross-sectional shape (polygon) of the intended polygonal columnar body 1 is completed by the plurality of flat plate members 10, and in the case of a regular octagon as shown in FIG. 1, the crossing angle that is a right angle to each side of the two adjacent flat plate members 10 is 135°.
  • the flat plate members 10 are arranged as they are without bending the flat plate members 10 as in the conventional technology.
  • the flat plate members 10 arranged on the stand are arranged with the side to be welded facing upward, and are welded in a state in which the welding torch faces downward.
  • a plurality of flat plate members 10 are arranged vertically while maintaining a predetermined interior angle, and welding is performed in a state where the welding torch faces horizontally or downward. In this case, it is not necessary to use a stand.
  • a placement jig (not shown) with abutment surfaces set at the above-mentioned predetermined intersection angle is used, and the flat plate members 10 are placed against the abutment surfaces of the placement jig, so that adjacent flat plate members 10 can be easily positioned.
  • a groove shape is formed at the butt joint between the adjacent flat plate members 10, and the groove is welded to connect the flat plate members 10 together via the weld W.
  • the flat plate members 10 are assembled, for example, into the above-mentioned ring body 10A, or a partial cross-section ring body obtained by dividing the cross section of the ring body 10A.
  • the ring body 10A or the partial cross-section ring body is then welded and connected to the upper side in the column axis direction at a predetermined installation position of the polygonal columnar body 1, thereby constructing the polygonal columnar body 1. As shown in FIG.
  • the butt joint between the adjacent flat plate members 10 may be a natural groove or a V-shaped groove, and the weld W may be formed by welding from the outside of the cross section, and is not limited to welding from one side (inside or outside), and the weld W may be formed from both sides.
  • X-shaped grooves 10c, 10d may be provided in advance at the ends of the flat plate members 10 adjacent in the circumferential direction, and the portions where the X-shaped grooves 10c, 10d meet may be welded from both the outside and inside of the cross section to form the welded portion W. Welding is not limited to being done from one side (inside or outside), and the welded portion W may be formed from both sides.
  • the divided ring bodies 10A etc. may be manufactured in a factory or yard near the installation location of the polygonal column 1, or they may be manufactured in a processing factory away from the installation location of the polygonal column 1, and then transported by truck or ship to the installation location of the polygonal column 1.
  • the polygonal columnar body 1 which is a polygonal cylindrical structure described above, has a horizontal cross-sectional shape formed with the same number of corners.
  • the polygonal columnar body 1 is formed by connecting steel flat plate members 10 in the circumferential direction and the column axial direction by welding.
  • the polygonal columnar body 1 has a polygonal cross-sectional shape with a hexagon or more and a 24-sided shape or less, and the plate thickness of the flat plate members 10 is 40 mm or more and 250 mm or less.
  • the ratio of the outer diameter D to the plate thickness t (outer diameter D/plate thickness t) of the polygonal cross section is 200 or less.
  • the plate thickness t of the flat plate member 10 is set to 40 mm or more and 250 mm or less, and the ratio of the outer diameter D to the plate thickness t (outer diameter D/plate thickness t) is set to 200 or less, so that local buckling can be suppressed, and the polygonal columnar body 1 can be manufactured with the minimum weld line length by selecting the specifications for the minimum number of corners that exhibits the same cross-sectional area as a circle and bending performance as a circle.
  • the above “equivalent” is defined as, for example, a maximum strength ratio of the polygonal cross section to the circular cross section of 0.9 (90%) or more. Therefore, in this embodiment, the arrangement of the flat plate members 10 can be constructed only by geometric adjustment, the bending process can be omitted, and the increase in cost can be suppressed by minimizing the costly assembly welding process. Furthermore, in this embodiment, since reinforcing members such as ribs are not required, a low-cost polygonal columnar body 1 can be provided.
  • the number of corners n of the polygonal cross section satisfies the above formula (1) or (2).
  • the minimum number of corners n that results in the same cross-sectional area and same bending performance as a circle according to the diameter-to-thickness ratio D/t using equation (1) or (2), it is possible to manufacture a polygonal columnar body 1 with a minimum weld line length.
  • the number of corners n (a natural number) of the polygonal cross section of the polygonal column 1 may satisfy formula (3) or formula (4).
  • the maximum strength ratio is 0.95 (95%) or more.
  • the number of corners n (a natural number) of the polygonal cross section of the polygonal column 1 may satisfy formula (5) or formula (6).
  • the maximum strength ratio is 0.99 (99%) or more.
  • the number of corners n (a natural number) of the polygonal cross section of the polygonal columnar body 1 may satisfy formula (7) or formula (8).
  • the maximum strength ratio is 0.90 (90%) or more.
  • the number of corners n (a natural number) of the polygonal cross section of the polygonal column 1 may satisfy formula (9) or formula (10).
  • the number of corners n (a natural number) of the polygonal cross section of the polygonal column 1 may satisfy formula (11) or formula (12).
  • the polygonal cylindrical structure is designed as described above.
  • the polygonal cross section is designed so that the ratio of the outer diameter D to the plate thickness t (outer diameter/plate thickness) is 200 or less.
  • the number of corners n of the polygonal cross section is designed to satisfy formula (1) or formula (2).
  • the polygonal cross section is designed to be a regular polygon.
  • the polygonal cross section is a regular polygon, and the cross-sectional shape is closer to a circle than polygons with different side lengths, so that the polygonal columnar body 1 can be manufactured with greater precision, with a specification set to the minimum number of corners (i.e., the minimum weld line length) that exhibits bending performance equivalent to that of a circle, as described above.
  • a polygonal cylindrical structure can be manufactured with greater precision by connecting flat plate members with the same side length, rather than connecting flat plate members with different side lengths.
  • the polygonal columnar body 1 of the wind power generation facility according to this embodiment, the design method of the polygonal cylindrical structure, and the foundation structure for offshore wind power generation facility using the polygonal cylindrical structure can achieve a good balance between exhibiting bending performance equivalent to that of a circular structure and reducing costs by omitting the bending process and reducing the welding process.
  • the polygonal column 1 shown in FIG. 1 has a truncated pyramid shape (tapered shape) whose cross-sectional shape gradually decreases toward the top.
  • Each flat plate member 10 constituting the polygonal column 1 shown in FIG. 1 has a trapezoid shape that decreases toward the top when viewed from the front.
  • the polygonal column 1' may have a cylindrical shape. That is, the outer diameter of the cross section of the polygonal column 1' may be approximately the same in the height direction.
  • Each flat plate member 10' constituting the polygonal column 1' shown in FIG. 8 has a rectangular shape when viewed from the front.
  • the polygonal column 1' By making the polygonal column 1' cylindrical, a process of cutting the flat plate member 10 into a trapezoid shape is not required.
  • the welded portion W' of the polygonal columnar body 1' shown in Figure 8 similarly to the welded portion W of the polygonal columnar body 1 shown in Figure 1, the vertical welded portions W2' of each ring body 10A' connected in the column axis direction are continuous with each other in the column axis direction, and the horizontal welded portions W1' of each ring body 10A' may be continuous with each other in the circumferential direction or may be staggered.
  • the polygonal columnar body 1B' may have a frustum shape only at a portion of the upper end, and a cylindrical shape below that.
  • the upper two-stage ring body 10B' has a frustum shape.
  • the welded part W'(W1',W2') is the same as the welded part W described above.
  • the polygonal body 1 has a tapered shape, it is desirable that the bottommost part, which is most susceptible to buckling, satisfy formula (1) or (2), and more desirably, the outer diameter D and plate thickness t may vary in the column axial direction as long as formula (1) or (2) is satisfied at any column axial height.
  • a horizontal load F was applied to the apex (upper part) of a cantilever beam model 2, which models the polygonal cylindrical structure shown in Figure 4, using a numerical simulation analysis (finite element analysis), and the strength of the polygonal cylindrical structure was evaluated.
  • a cantilever model 2 as shown in FIG. 4 was created for each of five analytical cases (CASE 1, CASE 2, CASE 3, CASE 4, CASE 5), and a numerical simulation analysis was performed by changing the diameter-to-thickness ratio (D/t) of the polygonal shape for each of analytical cases 1 to 5.
  • the specific conditions for each of analytical cases 1 to 5 are as shown in Table 1.
  • the diameter-to-thickness ratio (D/t) in the analytical cases was 40 for CASE 1, 80 for CASE 2, 120 for CASE 3, 160 for CASE 4, and 200 for CASE 5.
  • "outer diameter” is the distance between the center of the thickness of the flat plate member 10 and the center line of a cylinder that has the same reference circumference in cross section.
  • “Circumference” is the outer diameter (m) of a cylinder that has the same reference circumference in cross section multiplied by pi, that is, plate width multiplied by number of corners. "Area” is calculated by plate thickness (mm) multiplied by circumference (m), that is, circumference multiplied by plate thickness (plate width multiplied by number of corners multiplied by plate thickness).
  • Table 2 also shows the side width B (m), plate thickness t (mm), and width-thickness ratio (B/t) for each of the seven patterns of corner numbers n (number of corners n of the polygonal shape is 4, 6, 8, 10, 12, 16, and 24) in analysis cases 1 to 5.
  • n number of corners n of the polygonal shape is 4, 6, 8, 10, 12, 16, and 24
  • Table 2 also shows the side width B (m), plate thickness t (mm), and width-thickness ratio (B/t) for each of the seven patterns of corner numbers n (number of corners n of the polygonal shape is 4, 6, 8, 10, 12, 16, and 24) in analysis cases 1 to 5.
  • the analysis conditions for the circular cylindrical structure were that a regular 256-sided polygonal cylindrical structure with a side width of 0.123 m was considered to be equivalent to a cylinder in analysis cases 1 to 5.
  • the "side width" in Table 2 is the value of the circumference divided by the number of corners n.
  • the maximum stress (equivalent plastic strain, maximum strength) acting when a horizontal load (bending load) is applied to each polygonal cylindrical structure for each of the seven patterns of corner numbers n in analysis cases 1 to 5 was obtained by analysis.
  • the maximum stress (strength) acting when a horizontal load is applied to the circular cylindrical structure of the comparative example was obtained by analysis.
  • Figures 5(a) to (d) each show the cross-sectional shape of a cylindrical structure on the left side of the page, and an example of the distribution of equivalent plastic strain at maximum bending load based on the analysis results shown as a contour diagram on the right side of the page.
  • Figure 5(a) is an example of a quadrangular case with four corners.
  • Figure 5(b) is an example of an octagonal case with eight corners.
  • Figure 5(c) is an example of a dodecagonal case with 12 corners.
  • Figure 5(d) is an example of a comparative example with a circular cross section.
  • the symbol K in Figures 5(a) to (d) indicates the area (high stress area) where equivalent plastic strain occurs in each contour.
  • FIG. 6 shows the relationship between the number of corners n and the bending performance of the polygonal cylindrical structure, and shows the case where the diameter-thickness ratio D/t is 80 (CASE 2).
  • FIG. 6 shows only the case where the diameter-thickness ratio D/t is 80 as a representative example, but the graph shows roughly the same tendency in the cases where the diameter-thickness ratio D/t is 40 (CASE 1), 120 (CASE 3), 160 (CASE 4), and 200 (CASE 5).
  • the horizontal axis is the number of corners n
  • the vertical axis is the ratio (maximum strength ratio) of the maximum strength of the polygonal cylindrical structure (polygon) to the maximum strength of the circular cylindrical structure (cylinder).
  • maximum strength ratio it is defined that the polygonal cylindrical structure has the same cross-sectional area as the circular cylindrical structure and the maximum strength is 90% or more, and has the same strength (bending performance).
  • the number of corners n at which the maximum strength ratio is 90% or more is 6 or more. Specifically, it was confirmed that the maximum strength ratio is 90% or more when the number of corners is 6 or more (hexagon), the maximum strength ratio is 95% or more when the number of corners is 8 or more (octagon), and the maximum strength ratio is 99% or more when the number of corners is 10 or more (decagon). From this, it can be seen that the minimum number of corners n to obtain a maximum strength ratio of 90% or more equivalent to that of a circular cross section is 6 (hexagon).
  • the subject is a circular cylindrical structure with an outer diameter D of 8 to 12 m.
  • the plate thickness t required when the outer diameter D is 8 to 12 m is 40 mm or more.
  • the plate thickness t may be 50 mm or more, 60 mm or more, 65 mm or more, 70 mm or more, 75 mm or more, or 80 mm or more.
  • the upper limit of the plate thickness is set to 250 mm to prevent an increase in assembly costs due to an increase in the weight of the plate material.
  • the upper limit of the plate thickness is preferably 200 mm, and more preferably 150 mm.
  • Figure 7 shows the relationship between the number of corners n and the diameter-thickness ratio D/t that results in bending performance equivalent to or greater than that of a circular cylindrical structure (90%).
  • the horizontal axis is the number of corners n
  • the vertical axis is the diameter-thickness ratio D/t.
  • Figure 7 plots the points where the number of corners n is 90% or more, 95% or more, and 99% or more of the maximum strength ratio when the number of corners n is increased at a certain diameter-thickness ratio D/t.
  • the buckling strength insufficient region R2 is a region where the bending strength is significantly reduced due to local buckling of the plate as the side width B becomes longer and the plate thickness t becomes thinner as the number of corners n becomes smaller.
  • the cross-sectional performance insufficient region R3 is a region where the cross-sectional performance cannot be obtained when the number of corners n is small, as the second moment of area against the bending load becomes smaller.
  • the maximum strength ratio is 90% or more for any diameter-thickness ratio D/t, and the circular equivalent region R1 is reached, and the maximum strength ratio for the diameter-thickness ratio D/t also becomes large.
  • the maximum strength ratio is 99% or more for any diameter-thickness ratio D/t, and it is found that the bending performance is almost the same as that of a circular cross section.
  • the maximum strength ratio is less than 90% regardless of the diameter-thickness ratio D/t, which is in the region R3 where the cross-sectional performance is insufficient. In other words, when only the number of corners n is small, the second moment of area against the bending load becomes small, and therefore it is found that the cross-sectional performance cannot be obtained.
  • the condition for the polygonal tubular structure to ensure 90% or more of the circular performance (maximum strength ratio) of the circular tubular structure is that the number of corners n is 6 or more.
  • the condition for the polygonal tubular structure to ensure 95% or more of the circular performance (maximum strength ratio) of the circular tubular structure is that the number of corners n is 8 or more.
  • the condition for the polygonal tubular structure to ensure 99% or more of the circular performance (maximum strength ratio) of the circular tubular structure is that the number of corners n is 10 or more. Furthermore, when the diameter-thickness ratio D/t is 120, the condition for the polygonal tubular structure to ensure 90% or more of the circular performance (maximum strength ratio) of the circular tubular structure is that the number of corners n is 8 or more. When the diameter-thickness ratio D/t is 120, the condition for the polygonal tubular structure to ensure 95% or more of the circular performance (maximum strength ratio) of the circular tubular structure is that the number of corners n is 10 or more.
  • the condition for the polygonal tubular structure to ensure 99% or more of the circular performance (maximum strength ratio) of the circular tubular structure is that the number of corners n is 12 or more.
  • the number of corners n may be an even number.
  • the polygonal columnar body 1 (polygonal cylindrical structure) is exemplified as a foundation structure for a wind power generation facility, but another embodiment is a foundation structure for an offshore wind power generation facility that uses the above-mentioned polygonal columnar body 1 (polygonal cylindrical structure).
  • the polygonal columnar body 1 becomes, for example, the foundation of the offshore wind power generation facility.
  • it may be used for bottom-fixed monopile, gravity, or jacket-type foundation structures for offshore wind power, or floating TLP (Tension Leg Platform) or semi-submerged foundation structures, and it is also possible to make structures for other purposes into polygonal cylindrical structures.
  • a tapered polygonal columnar body 1 in which the cross-sectional shape tapers upward in the column axis direction, but a polygonal cylindrical structure that has the same cross-sectional shape and dimensions at any height in the column axis direction, that is, a polygonal cylindrical structure that does not taper overall, may also be used.
  • the number of corners n of the polygonal cross section of the polygonal columnar body 1 may be configured to satisfy the above formula (1) or (2), but is not limited to the number of corners n satisfying formula (1) or (2).
  • the present invention achieves a good balance between providing bending performance equivalent to that of a circular shape and reducing costs by eliminating bending processes and reducing welding processes.
  • Polygonal columnar body (polygonal cylindrical structure) 10 Flat plate member 10A: Ring body W: Welded portion

Landscapes

  • Rod-Shaped Construction Members (AREA)

Abstract

Selon la présente invention, une forme de section transversale dans la direction horizontale est formée par le même nombre de coins, et un corps colonnaire polygonal (1) est formé par des éléments de plaque plate en acier (10) couplés par soudage dans la direction circonférentielle et la direction d'axe de colonne. Le corps colonnaire polygonal (1) forme une section transversale polygonale présentant une forme de section transversale ayant de 6 à 24 carrés, et l'épaisseur de plaque des éléments de plaque plate (10) est de 40 à 250 mm. Le rapport du diamètre externe D à l'épaisseur de plaque t (diamètre externe D/épaisseur de plaque t) de la section transversale polygonale est de 200 ou moins.
PCT/JP2023/044779 2022-12-14 2023-12-14 Structure cylindrique polygonale, procédé de conception de structure cylindrique polygonale et structure de fondation pour installation de production d'énergie éolienne océanique utilisant une structure cylindrique polygonale WO2024128273A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2022199328 2022-12-14
JP2022-199328 2022-12-14

Publications (1)

Publication Number Publication Date
WO2024128273A1 true WO2024128273A1 (fr) 2024-06-20

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PCT/JP2023/044779 WO2024128273A1 (fr) 2022-12-14 2023-12-14 Structure cylindrique polygonale, procédé de conception de structure cylindrique polygonale et structure de fondation pour installation de production d'énergie éolienne océanique utilisant une structure cylindrique polygonale

Country Status (1)

Country Link
WO (1) WO2024128273A1 (fr)

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