Method for constructing spar-type floating body and steel-concrete composite structure part of offshore wind power generation equipment

Abstract

[Problem] To enable efficient and low-cost construction of a spar-type floating body and to simultaneously solve problems such as thermal cracking and bending cracking of concrete. [Solution] In a spar-type floating body 4, the lower half side is a steel-concrete composite structure part 4A in which concrete C is cast in a predetermined thickness on the inner surface side of an outer shell steel member 10 covering the outer periphery. In the steel-concrete composite structure part 4A, reinforcing bars placed in the concrete C include polygonal first reinforcing bars 35 and second reinforcing bars 36 disposed alternately in a staggered manner at intervals in the longitudinal direction of the floating body, the first reinforcing bars 35 and the second reinforcing bars 36 being constituted by a large number of joint parts a welded to the outer shell steel member 10 over a predetermined length range and at predetermined intervals in the circumferential direction of the outer shell steel member 10, and chord parts b linearly connecting ends of adjacent joint parts a, a. At the center position of each chord part b of the first reinforcing bars 35 and the second reinforcing bars 36, a predetermined cover to the outer surface of the concrete is ensured.

Description

Construction Method of Spar-Type Floating Body and Steel-Concrete Composite Structure Part of Offshore Wind Power Generation Equipment

[0001] The present invention relates to a construction method of a spar-type floating body and a steel-concrete composite structure part of offshore wind power generation equipment that can be constructed efficiently and at low cost.

[0002] Conventionally, power generation methods such as mainly hydraulic power, thermal power, and nuclear power generation have been adopted. In recent years, however, wind power generation that uses natural wind for power generation has attracted attention from the perspectives of environmental protection and effective utilization of natural energy. This wind power generation equipment includes onshore installation type and offshore (mainly at sea) installation type. In the case of Japan, which is surrounded by the sea on all sides and has mountainous terrain behind the coastal areas, there are few flatlands where stable winds can be expected in the coastal areas. On the other hand, Japan is surrounded by the sea on all sides, and has advantages such as easy access to winds suitable for power generation at sea and fewer installation restrictions. Therefore, in recent years, various types of offshore wind power generation equipment and floating body structures have been proposed.

[0003] The floating body structure is roughly classified into a barge-type floating body that floats the floating body on the water surface, a semi-submersible floating body that submerges the lower part of the floating body underwater and floats in a semi-submerged state, and a spar-type floating body that floats in a standing state like a fishing float.

[0004] Regarding the spar-type floating body, the applicant proposed a spar-type floating body 50 composed of a lower concrete floating body structure part 50A (hereinafter referred to as a concrete floating body part) in which a plurality of precast cylindrical bodies 51, 51... made of concrete are stacked in multiple stages in the height direction and each precast cylindrical body 51, 51... is tightened and integrated by PC steel bars 52, 52... as shown in FIG. 17 in Patent Document 1 below, and an upper steel floating body structure part 50B (hereinafter referred to as a steel floating body part) continuously provided above the concrete floating body part 50A.

[0005] The construction method for the concrete floating body section 50A involves placing the spar-type floating body 50 on its side and, as shown in Figure 18(A), inserting the PC steel rods 52, which extend upward from the precast cylindrical body 51, into the sheath 53 while connecting the precast cylindrical bodies 51, 51. Then, the anchor plate 54 is fitted into the box-shaped section, and tension is introduced into the PC steel rods 52 using the nut member 55 to integrate them. Finally, grout material is injected into the sheath 53 through the grout injection hole 54a.

[0006] Next, as shown in Figure 18(B), the coupler 56 is screwed onto the protruding portion of the PC steel bar 52, and the upper PC steel bar 52 is connected. Then, the PC steel bar 52 is inserted into the sheath 53 of the next precast cylindrical body 51 and installed. Grout material is also injected into the sheath 53 through the grout injection hole 57. By repeating this procedure sequentially, the concrete floating body 50A is constructed.

[0007] Patent No. 5274329

[0008] However, the concrete floating section 50A of the spar-type floating structure is constructed little by little by sequentially connecting precast cylindrical bodies 51 with PC steel bars 52, which meant that the construction of the floating structure required a lot of time, effort, and cost. Furthermore, as offshore wind power generation facilities have become larger, the spar-type floating structures have also become larger, which has led to problems such as increased concrete member thickness and an increase in the number of PC steel bars, resulting in even more time, effort, and cost.

[0009] Furthermore, if offshore wind power generation facilities were to become larger and have a power generation capacity of 15 MW, it is estimated that the diameter of the concrete floating section would be 15 m or more, and the thickness of the concrete members would be 70 cm or more. This would lead to problems such as increased susceptibility to temperature cracking during construction and bending cracking during installation in the concrete section.

[0010] Therefore, the main objective of the present invention is to provide a method for constructing a spar-type floating body and a steel-concrete composite structure for offshore wind power generation equipment that enables the efficient and low-cost construction of a spar-type floating body, while simultaneously solving problems such as temperature cracking and bending cracking of concrete.

[0011] To solve the aforementioned problems, the present invention according to claim 1 provides a spar-type floating offshore wind power generation facility in which the lower half is a steel-concrete composite structure in which concrete is poured to a predetermined thickness on the inner surface of an outer shell steel member covering the outer circumference, and the upper half is a steel structure having an outer shell steel member covering the outer circumference and being entirely made of steel members. In the steel-concrete composite structure, the reinforcing bars arranged inside the concrete are provided as follows: a polygonal first reinforcing bar composed of numerous joint portions welded to the outer steel member at predetermined intervals and over a predetermined length range in the circumferential direction of the outer steel member, and chord portions linearly connecting the ends of adjacent joint portions; and a polygonal second reinforcing bar composed of numerous joint portions welded to the outer steel member at predetermined intervals and over a predetermined length range in the circumferential direction of the outer steel member, and chord portions linearly connecting the ends of adjacent joint portions. These are arranged alternately in a staggered pattern with spacing in the longitudinal direction of the floating body, such that the circumferential position of the joint portions of the second reinforcing bar corresponds to the circumferential position of the chord portions of the first reinforcing bar, and a predetermined cover is secured on the outer surface of the concrete at the central position of the chord portions of the first and second reinforcing bars.

[0012] In the invention described in claim 1 above, the lower half of the spar-type floating body is replaced with a steel-concrete composite structure in which concrete is poured to a predetermined thickness on the inner surface of an outer shell steel member that covers the outer circumference, instead of the conventional concrete floating body portion.

[0013] By using a steel-concrete composite structure, manufacturing becomes more efficient and cost-effective. Furthermore, the thickness of the concrete members can be reduced, making thermal cracking less likely. The steel outer shell also reduces the likelihood of bending cracking. Even if thermal or bending cracking occurs, it will not cause water leakage. Additionally, the overall weight of the floating structure can be reduced, resulting in a more economical floating structure.

[0014] Furthermore, in order to prevent deformation of the outer steel member, the present invention provides a function to prevent deformation of the outer steel member, particularly in the reinforcing bars embedded in the concrete. Generally, it is common to reinforce the outer steel member by providing stiffening ribs on its inner surface, but in the present invention, deformation when the outer steel member is placed horizontally is suppressed by making the reinforcing bars a three-dimensional structure. Specifically, in the steel-concrete composite structure, the reinforcing bars arranged inside the concrete are polygonal first and second reinforcing bars, each composed of numerous joint portions welded to the outer steel member at predetermined intervals and over a predetermined length range in the circumferential direction of the outer steel member, and chord portions linearly connecting the ends of adjacent joint portions. These are arranged alternately in a staggered pattern and spaced apart in the longitudinal direction of the floating body, such that the circumferential position of the joint portion of the second reinforcing bar corresponds to the circumferential position of the chord portion of the first reinforcing bar, and a predetermined cover is secured on the outer surface of the concrete at the central position of the chord portions of the first and second reinforcing bars. By giving the reinforcing steel the function of reinforcing concrete while simultaneously suppressing the deformation of the outer steel shell members, it becomes possible to manufacture steel-concrete composite structures at low cost, and it becomes possible to create rational steel-concrete composite structures with various advantages as described later.

[0015] As part of the present invention according to claim 2, a spar-type floating offshore wind power generation facility is provided, wherein at the boundary between the lower half steel-concrete composite structure and the upper half steel structure, the plate thickness of the outer shell steel member of the steel-concrete composite structure and the outer shell steel member of the steel structure are the same.

[0016] In the invention described in claim 2 above, the plate thickness of the outer shell steel member of the steel-concrete composite structure and the outer shell steel member of the steel structure are made the same so that the load from the steel structure can be easily transmitted.

[0017] As part of the present invention according to claim 3, a spar-type floating structure for a cured wind power generation facility according to claim 1 is provided, having an inner steel member for crack prevention in the steel-concrete composite structure that adheres closely to the inner surface of the concrete and covers the entire surface of the concrete.

[0018] The invention described in claim 3 above is characterized in that, in the steel-concrete composite structure, an inner steel member for crack prevention is provided so as to be in close contact with the inner surface of the concrete and cover the entire surface of the concrete. By providing the inner steel member for crack prevention, it becomes possible to further prevent cracking of the concrete.

[0019] As part of the present invention according to claim 4, a method for constructing a steel-concrete composite structure according to either claim 1 or 2 is provided, wherein the outer shell steel member has a structure in which a plurality of ring-shaped outer shell steel members are connected by welding, and the method for constructing a steel-concrete composite structure is provided, comprising: a first step of fixing the first and second reinforcing bars to the inner surface side of the outer shell steel member by welding while the ring-shaped outer shell steel member is laid flat with its opening surface in the vertical direction; a second step of lifting the ring-shaped outer shell steel member into a horizontal position with its opening surface in the horizontal direction and sequentially connecting the ring-shaped outer shell steel members to each other by welding; and a third step of pouring concrete of a predetermined thickness onto the inner surface side of the outer shell steel member after all the ring-shaped outer shell steel members have been connected and the outer shell steel member is completed.

[0020] The invention described in claim 4 above relates to a method for constructing a steel-concrete composite structure according to claims 1 and 2. When fixing reinforcing bars to the outer steel shell member by welding, it is necessary to do so while the outer steel shell member is not deformed. Therefore, it is desirable to construct the structure by a third step in which, after the ring-shaped outer steel shell member is laid flat with the opening surface in the vertical direction, the ring-shaped outer steel shell member is lifted into a horizontal position with the opening surface in the horizontal direction, and the ring-shaped outer steel shell members are sequentially connected to each other by welding, and finally, after all the ring-shaped outer steel shell members have been connected and the outer steel shell member is completed, concrete of a predetermined thickness is poured into the inner surface of the outer steel shell member.

[0021] As part of the present invention according to claim 5, a method for constructing a steel-concrete composite structure as described in claim 3 is provided, wherein the outer shell steel member has a structure in which a plurality of ring-shaped outer shell steel members are connected by welding, and the first step is to fix the first and second reinforcing bars to the inner surface side of the outer shell steel member by welding while the ring-shaped outer shell steel member is laid flat with its opening surface in the vertical direction, a second step is to suspend the ring-shaped outer shell steel member in a horizontal position with its opening surface in the horizontal direction, and sequentially connect the ring-shaped outer shell steel members to each other by welding, and once all the ring-shaped outer shell steel members have been connected and the outer shell steel member is completed, the crack-prevention inner shell steel member is installed on the inner surface side of the outer shell steel member with a predetermined distance between them, and concrete is poured into the space between the outer shell steel member and the crack-prevention inner shell steel member.

[0022] The invention described in claim 5 above relates to a method for constructing a steel-concrete composite structure according to claim 3. When fixing reinforcing bars to the outer steel shell member by welding, it is necessary to do so while the outer steel shell member is not deformed. Therefore, it is desirable to construct the structure by a third procedure in which, first, the ring-shaped outer steel shell member is laid flat with its opening face in the vertical direction and the reinforcing bars are welded to it, then the ring-shaped outer steel shell member is lifted into a horizontal position with its opening face in the horizontal direction and the ring-shaped outer steel shell members are sequentially connected to each other by welding, and finally, after all the ring-shaped outer steel shell members have been connected and the outer steel shell member is completed, the crack-prevention inner steel shell member is installed on the inner surface side of the outer steel shell member with a predetermined gap between them, and concrete is poured into the space between the outer steel shell member and the crack-prevention inner steel shell member.

[0023] As explained in detail above, the present invention makes it possible to construct spar-type floating bodies efficiently and at low cost, while simultaneously solving problems such as temperature cracking and bending cracking of concrete.

[0024] This is an overall view of the spar-type offshore wind power generation facility 1. This is a longitudinal cross-sectional view of the floating body 4. This shows the steel-concrete composite structure 4A, (A) is a cross-sectional view and (B) is a plan view of the main part. This is an enlarged view of part IV of Figure 3. This is a diagram of the manufacturing procedure for the outer shell steel member 10. This shows the movable formwork device 9, (A) is a side view and (B) is a cross-sectional view of BB. (A) to (D) are the manufacturing procedure (part 1) for the bottom portion of the steel-concrete composite structure 4A. (E) to (G) are the manufacturing procedure (part 2) for the bottom portion of the steel-concrete composite structure 4A. (A) to (D) are the manufacturing procedure (part 1) for the general portion of the steel-concrete composite structure 4A. This is a model diagram for FRAME calculation. This is a table showing the FRAME calculation results. This is an enlarged view of the FRAME calculation model showing the nodal part showing the maximum displacement. This is an enlarged view of the FRAME calculation model showing the member showing the maximum sectional force. This is a cross-sectional view of the steel-concrete composite structure 4A according to the second embodiment example. This is an enlarged view of section XV in Figure 14. This is a diagram showing the concrete pouring procedure for the steel-concrete composite structure section 4A according to the second embodiment. This is a cross-sectional view of a conventional spar-type floating body 50, in which the lower half is a concrete floating body section 50A and the upper half is a steel floating body section 50B. These are diagrams (A) and (B) showing the procedure for connecting the precast cylindrical body 51 of the concrete floating body section 50A with PC steel bars 52.

[0025] Embodiments of the present invention will be described in detail below with reference to the drawings.

[0026] [Spar-type floating offshore wind power generation facility 1] First, the spar-type floating offshore wind power generation facility 1 according to the present invention will be described in detail with reference to Figures 1 and 2.

[0027] As shown in Figure 1, the aforementioned spar-type floating offshore wind power generation facility 1 consists of a spar-type floating body 4, a plurality of mooring lines 5 connected to the spar-type floating body 4, a tower 6 connected to the top of the spar-type floating body 4, and a nacelle 7 and a plurality of blades 8, 8... installed at the top of the tower 6.

[0028] As shown in Figure 2, the spar-type floating body 4 has a steel-concrete composite structure 4A in which concrete C of a predetermined thickness is poured into the inner surface of an outer shell steel member 10 that covers the outer circumference in the lower half, and a steel structure 4B in which an outer shell steel member 12 that covers the outer circumference is made entirely of steel members.

[0029] The hollow portion of the spar-type floating body 4 can be filled with ballast material such as water, gravel, fine aggregate or coarse aggregate, or metal particles, and the buoyancy (draft) can be adjusted. The filling and discharging of ballast material can be done by employing the fluid transport method previously proposed by the applicant in Japanese Patent Application Publication No. 2012-201217.

[0030] As will be described in detail later, the steel-concrete composite structure 4A is designed with a three-dimensional structure in which the reinforcing bars arranged inside the concrete C are arranged to suppress deformation when the outer steel member 10 is placed horizontally. By giving the reinforcing bars both the function of reinforcing the concrete and the function of suppressing deformation of the outer steel member 10, it becomes possible to manufacture the steel-concrete composite structure 4A at a low cost, and it becomes possible to create a rational steel-concrete composite structure 4A with various advantages as described later.

[0031] It is desirable that the bottom of the steel-concrete composite structure 4A also be a composite structure in which concrete C0 is poured on the inner surface side of the bottom steel plate 11. As will be described later, for manufacturing reasons, an opening 30 is provided in this bottom and closed after the concrete C on the bottom side has been poured.

[0032] The steel structure 4B is a cylindrical body whose outer circumference is surrounded by an outer shell steel member 12, and is composed of a steel cylindrical body 17 located on the lower side and a steel cylindrical body 18 located on the upper side. The lower part of the steel cylindrical body 17 has the same outer diameter as the outer shell steel member 10 of the steel-concrete composite structure 4A. The upper part of the steel cylindrical body 17 has a truncated cone shape with a gradually narrowing diameter. The upper steel cylindrical body 18 is a cylindrical body with an outer diameter that is continuous with the upper outer diameter of the steel cylindrical body 17, and is connected to the lower steel cylindrical body 17 by bolts or welding (bolt fastening in the illustrated example). These steel cylindrical bodies 17 and 18 are composed of steel rings divided into predetermined weight units, and each steel ring is integrated by welding in the circumferential direction.

[0033] At the boundary between the steel-concrete composite structure 4A and the steel structure 4B, as shown in Figure 2, it is desirable to make the plate thickness of the outer steel member 10 of the steel-concrete composite structure 4A and the outer steel member 12 of the steel structure 4B the same. This makes it easier for the load from the steel structure 4B to be transmitted to the steel-concrete composite structure 4A.

[0034] Furthermore, at this boundary, as shown in Figure 2, it is desirable to extend the outer shell steel member 10 of the steel-concrete composite structure 4A toward the steel structure 4B by a predetermined length and join it with the outer shell steel member 12 of the steel structure 4B by welding at a distance S from the concrete C (welded joint 19). This prevents the concrete C from spalling due to the heat input during welding.

[0035] On the other hand, the tower 6 is made of steel, concrete, or PRC (prestressed reinforced concrete), but it is preferable to use one made of steel to reduce the total weight. The outer diameter of the tower 6 and the outer diameter of the upper steel cylindrical body 18 are almost the same, and the outer shape is continuous in the vertical direction without any steps or other differences.

[0036] As shown in Figure 1, the mooring point P of the mooring rope 5 to the floating body 4 is set below the sea surface and higher than the center of gravity G of the floating body 4. Therefore, it is possible to prevent ships from coming into contact with the mooring rope 5. In addition, a resistance moment is generated at the mooring point P around the center of gravity G of the floating body 4 to prevent the floating body 4 from tilting too much, so that the tilted posture of the tower 6 can be properly maintained.

[0037] On the other hand, the nacelle 7 is a device equipped with a generator that converts the rotation of the wind turbine into electricity, a controller that can automatically change the angle of the blades 8, and other components.

[0038] [Regarding the steel-concrete composite structure 4A] In the steel-concrete composite structure 4A, as shown in Figures 3 and 4, the reinforcing bars arranged inside the concrete C are a polygonal first reinforcing bar 35 composed of a number of joint portions a welded to the outer shell steel member 10 at predetermined intervals and over a predetermined length range in the circumferential direction of the outer shell steel member 10, and chord portions b linearly connecting the ends of adjacent joint portions a, a, and the outer shell steel member 10 at predetermined intervals and over a predetermined length range in the circumferential direction of the outer shell steel member 10 A polygonal second reinforcing bar 36, composed of numerous welded joint portions a and chord portions b linearly connecting the ends of adjacent joint portions a, a, is arranged alternately in a staggered pattern with spacing in the longitudinal direction of the floating body, such that the circumferential position of the joint portions of the second reinforcing bar 36 corresponds to the circumferential position of the chord portions of the first reinforcing bar 35 in the longitudinal direction of the floating body, and a predetermined cover K is secured on the outer surface of the concrete C at the central position of the chord portions b of the first reinforcing bar 35 and the second reinforcing bar 36.

[0039] In typical reinforcement arrangements, the reinforcing bars are spaced apart from the outer steel member 10 and arranged parallel to it. However, in this invention, in order to provide a function to prevent deformation when the outer steel member 10 is oriented sideways, a portion of the reinforcing bars is welded to the outer steel member 10, and a three-dimensional structure is created toward the inward side, thereby suppressing deformation into an elliptical shape due to its own weight when the circular outer steel member 10 is oriented sideways. Furthermore, by reinforcing the outer steel member 10 with reinforcing bars instead of stiffening ribs, the following advantages can be obtained: (1) By using reinforcing bars, it is possible to create a rational structure by combining deformation suppression during the construction of the steel-concrete composite structure 4A with load-bearing members upon completion. (2) After concrete pouring, the structure becomes SRC, enabling integration of the outer steel member 10, reinforcing bars 35, 36 and concrete C. (3) The welding area is reduced compared to stiffening ribs, resulting in reduced welding time and costs. (4) When concrete is poured, it becomes less likely for the fluidity of the concrete to decrease or for air to be mixed in, making it easier to ensure the quality of the concrete.

[0040] The number of joint portions a between the first reinforcement bar 35 and the second reinforcement bar 36 should preferably be around 20 to 32 around the entire circumference. The length of the joint portions a should be approximately 300 to 1200 mm, preferably 500 to 1000 mm.

[0041] The length of the chord portion b will be naturally determined from the condition that a predetermined cover K is ensured with respect to the outer surface of the concrete C at the central position of the chord portions b of the first reinforcing bar 35 and the second reinforcing bar 36. However, since the number and length of the chord portions b are factors that greatly affect the deformation suppression effect, it is necessary to determine them carefully. The length of the chord portion b varies depending on the diameter of the floating body 4, but is generally about 1000 to 4000 mm, preferably about 2000 to 3500 mm. The ratio of the joint portion a to the chord portion b is desirably such that joint portion a / chord portion b is 0.20 to 0.40, preferably about 0.25 to 0.25. Therefore, the length of the joint portion a is preferably about 200 to 1600 mm, preferably about 400 to 1400 mm, based on the length of the chord portion b and the ratio of the joint portion a to the chord portion b.

[0042] The interval P in the longitudinal direction of the floating body between the first reinforcing bar 35 and the second reinforcing bar 36 varies depending on the diameter of the reinforcing bar used, but is preferably about 200 to 400 mm.

[0043] <Fabrication of the Steel-Concrete Composite Structure Portion 4A> (Fabrication of the Outer Shell Steel Member 10) The outer shell steel member 10 is made of a steel member (steel plate). In fabrication, ring-shaped outer shell steel members 10A, 10A... divided in the longitudinal direction are fabricated separately, and the steel outer shell portion 10 of a predetermined length is constructed by sequentially welding each of these ring-shaped outer shell steel members 10A in a horizontally oriented state (where the opening surface is in the horizontal direction).

[0044] Therefore, as shown in FIG. 5, the ring-shaped outer shell steel members 10A, 10A... are placed flat with the opening surface in the vertical direction, and the first reinforcing bar 35 and the second reinforcing bar 36 are fixed to the outer shell steel member by welding.

[0045] Next, using the first bridge crane 37, the ring-shaped outer shell steel members 10A are sequentially placed on the rotating frames 39, 39..., and the procedure of welding the ring-shaped outer shell steel members 10A in the circumferential direction while rotating them around their axis is repeated to complete the steel outer shell 10. That is, the first ring-shaped outer shell steel member 10A and the second ring-shaped outer shell steel member 10A are placed on the rotating frame 39, and they are welded together in the circumferential direction while rotating them around their axis. Next, the next ring-shaped outer shell steel member 10A is set in an adjacent position, and the entire assembly is rotated around its axis by the rotating frames 39, 39..., and the process of welding them together in the circumferential direction is repeated for all the ring-shaped outer shell steel members 10A, 10A... to complete the outer shell steel member 10. Furthermore, the connection work of the ring-shaped outer shell steel members 10A, 10A... is carried out outdoors at the on-site manufacturing yard G, and if it rains, the welding and painting work cannot be performed. As this can cause delays in the process, it is desirable to cover the area with a mobile tent 38 so that welding and painting work can be carried out even in light rain.

[0046] <Concrete pouring on the inner surface of the outer steel member 10> First, the movable formwork device 9 used to pour concrete on the inner surface of the outer steel member 10 will be described in detail with reference to Figure 6.

[0047] The movable formwork device 9 consists of a formwork support device 13 with a slide guide 23 provided horizontally between a front support leg 20 and a rear support leg 21, and a circular formwork device 14 that is fitted onto the slide guide 23, is movable along the slide guide 23, and allows formwork plates to be installed in a circular shape around the entire circumference at a predetermined radius. The movable formwork device 9 is set inside the outer steel member 10 of the steel-concrete composite structure 4A with the outer steel member 10 installed in a horizontal position, and concrete is poured inside the outer steel member 10 of the steel-concrete composite structure 4A in the direction of its entire circumference. With one span being about 6 to 12 m, concrete is poured over the entire length of the steel-concrete composite structure 4A by repeatedly moving and pouring concrete.

[0048] The following will be described in more specific detail.

[0049] The front support leg 20 and the rear support leg 21 have a jack-type leg 24 that is telescopically extendable downward, and the height position thereof is adjustable. A slide guide 23 is horizontally installed between the front support leg 20 and the rear support leg 21. In the illustrated example, the shape of the slide guide 23 is rectangular.

[0050] The circular formwork device 14 has a rectangular sleeve 24 that fits over the slide guide 23 and is movable along the slide guide 23. On the outer surface of the sleeve 24, there are jack support rods 26, 26... that project outward at appropriate intervals over the entire circumference, and formwork plates 27, 27... that are supported by these jack support rods 26, 26... and are divided into a plurality in the circumferential direction. When these formwork plates 27, 27... are positioned at a predetermined position, they form a complete circle, and a concrete casting space with a certain thickness is formed between them and the outer shell steel member 10. The formwork plates 27, 27... are movable in the outer circumferential direction by jacks provided on the jack support rods 26, so that demolding can be easily performed after concrete casting. The circular formwork device 14 has a formwork distance L in the direction of the slide guide 23. The length of the formwork distance L is preferably about 6 to 12 m.

[0051] Fixing jack facilities 28, 29 are provided on the front upper part and the rear upper part of the circular formwork device 14 with respect to support members extending in the front-rear direction from the circular formwork device 14, respectively. With these fixing jack facilities 28, 29, the circular formwork device 14 can be firmly supported at a predetermined position.

[0052] Next, regarding the concrete pouring method on the inner surface side of the outer shell steel member 10, it will be described in detail by dividing it into the bottom part of the steel-concrete composite structure part 4A and the general part of the steel-concrete composite structure part 4A. Note that the illustration of the first reinforcing bar 35 and the second reinforcing bar 36 is omitted.

[0053] <Concrete pouring procedure for the bottom portion of the steel-concrete composite structure 4A> (Step 1) As shown in Figure 7(A), the outer steel member 10 of the steel-concrete composite structure 4A is installed in a horizontal orientation. At this time, an opening 30 is provided at the bottom of the steel-concrete composite structure 4A that is large enough for the movable formwork device 9 to pass through. It is desirable that the outer periphery of the opening 30 be a composite structure of steel and concrete.

[0054] The movable formwork device 9 is installed with its slide guide 23 passing through the opening 30, and the circular formwork device 14 is positioned at the bottom of the steel-concrete composite structure 4A. Formwork plates 27, 27... are installed on the inner surface of the outer shell steel member 10 that covers the entire circumference, so that concrete can be poured to a predetermined thickness. The circular formwork device 14 is supported by the fixing jack equipment 28, 29 to prevent movement, and end formwork 31 is installed around the entire circumference of the front end (right side of the drawing) of the formwork plates 27, 27... to close the concrete pouring space.

[0055] (Second step) As shown in Figure 7(B), concrete C1 is poured into the space between the outer steel member 10 of the steel-concrete composite structure 4A and the formwork plates 27, 27...

[0056] (Third step) As shown in Figure 7(C), with the circular formwork device 14 in position, the formwork support device 13 is moved to the inner side (right side in the drawing) of the steel-concrete composite structure 4A. The movement is performed with the front support legs 20 and rear support legs 21 of the formwork support device 13 released, and only the formwork support device 13 is moved using human power or a powered moving device. Once the movement is complete, as shown in the figure, the jack-type legs 24 of the front support legs 20 and rear support legs 21 are extended and brought to the ground.

[0057] (Fourth step) As shown in Figure 7(D), the circular formwork device 14 is removed from the concrete C1, and with the formwork support device 13 in place, the circular formwork device 14 is moved to the inner side of the steel-concrete composite structure 4A. Then, formwork plates 27, 27... are installed adjacent to the poured concrete C1 and on the inner side of the outer shell steel member 10 that covers the entire circumference, so that concrete can be poured to a predetermined thickness. Also, as shown in Figure 8(E), the circular formwork device 14 is supported so as not to move by the fixing jack equipment 28, 29, and end formwork 31 is installed around the entire circumference at the front end (front end in the direction of travel) of the formwork plates 27, 27... to close the concrete pouring space.

[0058] (Step 5) As shown in Figure 8(F), concrete C2 is poured into the space between the outer steel member 10 of the steel-concrete composite structure 4A and the formwork plates 27, 27...

[0059] (Next Step) By repeating the second to fourth steps described above, concrete is sequentially poured to a predetermined thickness into the inner surface of the outer steel member 10 of the steel-concrete composite structure 4A. Once the movable formwork device 9 has completely entered the interior of the steel-concrete composite structure 4A, as shown in Figure 8(G), the opening 30 formed at the bottom of the steel-concrete composite structure 4A is closed. Specifically, for example, as shown in Figure 8(G), the inner side of the annular steel plate 32 provided on the outer periphery of the opening 30 is closed with a circular steel plate 33, and then concrete 34 is poured inward to close the opening 30 with a composite structure of steel and concrete.

[0060] <Concrete pouring procedure for the general portion of the steel-concrete composite structure 4A> (Step 1) As shown in Figure 9(A), concrete C is poured into the space between the outer steel member 10 of the steel-concrete composite structure 4A and the formwork plates 27, 27...

[0061] (Second Step) As shown in Figure 9(B), with the circular formwork device 14 in position, the formwork support device 13 is moved to the interior side of the steel-concrete composite structure 4A (to the right in the drawing, towards the steel structure 4B). The movement is performed with the front support legs 20 and rear support legs 21 of the formwork support device 13 released, and only the formwork support device 13 is moved using human power or a powered moving device. Once the movement is complete, as shown in the figure, the jack-type legs 24 of the front support legs 20 and rear support legs 21 are extended and brought to the ground.

[0062] (Third step) As shown in Figure 9(C), with the formwork support device 13 in place, the circular formwork device 14 is moved to the inner side of the steel-concrete composite structure 4A (to the right in the drawing, on the steel structure 4B side), and formwork plates 27, 27... are installed adjacent to the already poured concrete and on the inner side of the outer shell steel member 10 that covers the entire circumference, so that concrete C of a predetermined thickness can be poured. Also, as shown in the same figure, the circular formwork device 14 is supported so as not to move by the fixing jack equipment 28, 29, and end formwork 31 is installed around the entire circumference at the front end (front end in the direction of travel) of the formwork plates 27, 27... to close the concrete pouring space.

[0063] (Subsequent steps) By repeating the above steps 1 to 3, concrete is sequentially poured to a predetermined thickness into the inner surface of the outer steel member 10 of the steel-concrete composite structure 4A.

[0064] <Completion of the spar-type floating body 4> In the steel-concrete composite structure 4A, once the concrete C has been poured onto the inner surface of the outer shell steel member 10 covering the outer circumference, the steel structure 4B is joined by welding around the entire circumference to complete the spar-type floating body 4.

[0065] Next, FRAME calculations were performed for the outer shell steel member 10 reinforced with the first reinforcing bar 35 and the second reinforcing bar 36 (example of the present invention) and for the case where only the outer shell steel member 10 without reinforcing bar reinforcement is used (comparative example). By comparing the maximum displacement and maximum sectional force of each when placed horizontally in the state before concrete pouring (under its own weight), the deformation suppression effect of the reinforcing bar in the outer shell steel member 10 of the present invention was verified.

[0066] As shown in Figure 10, the analytical model of the present invention consists of an outer steel shell member with a radius of 8000 mm (thickness: t=40 mm), and a structure in which first reinforcement bars: D51@400 and second reinforcement bars: D51@400 are arranged on the inner surface of this outer steel shell member. Since the first and second reinforcement bars are arranged alternately, the actual reinforcement bar spacing is 200 mm. The nodes are set at 1° intervals in a counterclockwise direction, with node 1 being the 0° position of the SL (spring line). The member numbering is such that the member connecting node 1 and node 2 is designated as member 1.

[0067] The comparative example model was a model obtained by omitting the first and second reinforcing bars from the analytical model of the present invention.

[0068] The analysis results are shown in Figure 11. The upper section shows the comparative model, where a maximum displacement of 321 mm occurs at node 91 (see Figure 12) and a maximum cross-sectional force of 533 N / mm2 occurs at member 301 (see Figure 13). In contrast, the lower section shows the present invention model, where a maximum displacement of 25.9 mm occurs at node 89 (see Figure 12) and a maximum cross-sectional force of 105 N / mm2 occurs at member 300 (see Figure 13).

[0069] As is clear from this comparative analysis, in the present invention, the structure reinforced with three-dimensional first reinforcement bars 35 and second reinforcement bars 36 makes it possible to reduce the maximum displacement at the top of the floating body to about 1 / 12, and also to reduce the maximum sectional force to about 1 / 5.

[0070] [Second Embodiment Example] In the second embodiment example, as shown in Figures 14 and 15, an inner shell steel member 40 for crack prevention is provided in the steel-concrete composite structure 4A so as to be in close contact with the inner surface of the concrete C and cover the entire surface of the concrete.

[0071] The crack-prevention inner steel member 40 is a steel material that prevents cracks from occurring in the concrete C, so it can be made of a thinner steel plate than the outer steel member 10. The crack-prevention inner steel member 40 is arranged to cover the entire surface of the concrete C.

[0072] As shown in Figure 16, the construction involves preparing a cylindrical crack-prevention inner steel member 40 having a length equivalent to one span length when concrete is poured. When concrete is poured, the circular formwork device 14 of the movable formwork device 9 is used to position the crack-prevention inner steel member 40 on the inner side of the outer steel member 10 with a predetermined gap between them. Then, concrete from the concrete mixer truck 42 is pumped by the concrete pump 41 and poured into the space between the outer steel member 10 and the crack-prevention inner steel member 40. Concrete pouring openings are also provided in a stepped manner on the side of the crack-prevention inner steel member 40, and concrete is poured in through these concrete pouring openings.

[0073] Since the crack-prevention inner steel members 40 are placed for each span of concrete pouring, adjacent already installed crack-prevention inner steel members 40 are connected by welding.

[0074] [Other Examples of Configurations] (1) In the above example of configuration, when concrete is poured into the bottom portion of the steel-concrete composite structure 4A, as shown in Figure 8(G), the opening 30 formed in the bottom of the steel-concrete composite structure 4A is closed immediately after the movable formwork device 9 has completely entered the interior of the steel-concrete composite structure 4A. However, the step of closing the opening 30 can be performed at any time after the movable formwork device 9 has completely entered the interior of the steel-concrete composite structure 4A. For example, it may be done after all the concrete has been poured into the inner surface of the outer shell steel member 10, or after the steel structure 4B has been joined to the steel-concrete composite structure 4A.

[0075] 1...Offshore wind power generation equipment, 4...Spar-type floating body, 4A...Steel-concrete composite structure, 4B...Steel structure, 5...Mooring rope, 6...Tower, 7...Nacelle, 8...Blade, 9...Mobile formwork device, 10...Outer shell steel member, 10A...Steel ring, 13...Formwork support device, 14...Circular formwork device, 20...Front support leg, 21...Rear support leg, 23...Slide guide, 24...Jack-type leg, 26...Jack support rod, 27...Formwork plate, 27...Formwork plate, 28・29...Fixing jack equipment, 30...Opening, 31...End formwork, 35...First reinforcing bar, 36...Second reinforcing bar, 40...Inner shell steel member for crack prevention, a...Joint part, b...Chord part, K...Cover

Claims

1. The spar-type floating body of an offshore wind power generation facility is configured such that the lower half is a steel-concrete composite structure in which concrete of a predetermined thickness is poured onto the inner surface of an outer shell steel member covering the outer circumference, and the upper half is a steel structure having an outer shell steel member covering the outer circumference and being entirely made of steel members, wherein the reinforcing bars arranged inside the concrete are a polygonal first reinforcing bar composed of numerous joint portions welded to the outer shell steel member at predetermined intervals and over a predetermined length range in the circumferential direction of the outer shell steel member, and chord portions linearly connecting the ends of adjacent joint portions, and a polygonal second reinforcing bar composed of numerous joint portions welded to the outer shell steel member at predetermined intervals and over a predetermined length range in the circumferential direction of the outer shell steel member, and chord portions linearly connecting the ends of adjacent joint portions, and are arranged alternately in a staggered pattern and spaced apart in the longitudinal direction of the floating body such that the circumferential position of the joint portions of the second reinforcing bar corresponds to the circumferential position of the chord portions of the first reinforcing bar. A spar-type floating structure for offshore wind power generation equipment, characterized in that a predetermined concrete cover is ensured at the central position of the chord portions of the first and second reinforcing bars relative to the outer surface of the concrete.

2. The spar-type floating offshore wind power generation facility according to claim 1, wherein at the boundary between the lower half steel-concrete composite structure and the upper half steel structure, the plate thickness of the outer shell steel member of the steel-concrete composite structure and the outer shell steel member of the steel structure are the same.

3. The spar-type floating body of a cured wind power generation facility according to claim 1, wherein the steel-concrete composite structure has an inner steel member for crack prevention that adheres closely to the inner surface of the concrete and covers the entire surface of the concrete.

4. A method for constructing a steel-concrete composite structure according to either claim 1 or 2, wherein the outer shell steel member has a structure in which a plurality of ring-shaped outer shell steel members are connected by welding, and the method comprises: a first step of fixing the first and second reinforcing bars to the inner surface of the outer shell steel member by welding while the ring-shaped outer shell steel member is laid flat with its opening surface in the vertical direction; a second step of lifting the ring-shaped outer shell steel member in a horizontal position with its opening surface in the horizontal direction and sequentially connecting the ring-shaped outer shell steel members to each other by welding; and a third step of pouring concrete of a predetermined thickness onto the inner surface of the outer shell steel member after all the ring-shaped outer shell steel members have been connected and the outer shell steel member is completed.

5. A method for constructing a steel-concrete composite structure according to claim 3, wherein the outer shell steel member has a structure in which a plurality of ring-shaped outer shell steel members are connected by welding, and the method comprises: a first step of fixing the first and second reinforcing bars to the inner surface side of the outer shell steel member by welding, with the ring-shaped outer shell steel member in a horizontal position with the opening surface in the vertical direction; a second step of lifting the ring-shaped outer shell steel member in a horizontal position with the opening surface in the horizontal direction, and sequentially connecting the ring-shaped outer shell steel members to each other by welding; and a third step of, once all the ring-shaped outer shell steel members have been connected and the outer shell steel member is completed, installing the crack-prevention inner shell steel member on the inner surface side of the outer shell steel member with a predetermined distance between them, and pouring concrete into the space between the outer shell steel member and the crack-prevention inner shell steel member.

Images