Precast member

Abstract

Provided is a precast member or the like that enables safe and easy construction of a wooden board on the surface of the precast member. 【Solution means】The precast member 1 has, in a state before being installed as a part of a building, a concrete main body 2, a wooden board 3 disposed on the surface of the main body 2, a joining member 4 that joins the main body 2 and the wooden board 3 with one end embedded in the main body 2 and the other end embedded in the wooden board 3, and an elastic layer 5 provided between the main body 2 and the wooden board 3. The precast member 1 constitutes, for example, a balcony of a building.

Description

Technical Field

[0001] The present invention relates to precast members.

Background Art

[0002] For the purpose of improving workability and shortening the construction period, when constructing a building, precast members prefabricated in a factory or the like may be used as part of the building. Patent Documents 1 and 2 describe constructing a balcony or eaves by joining a precast member to a building frame.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, from the perspective of CO2 fixation and the like that contribute to SDGs (Sustainable Development Goals), the use of wooden materials in buildings has been increasing. The same is true when constructing a building using precast members. As an example, wooden boards are later constructed as exterior finishing materials on the surface of precast members joined to the building frame. However, the later construction of wooden boards often involves working at heights, requires reliable safety measures, and is time-consuming and costly.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a precast member or the like that can safely and easily construct wooden boards on the surface of the precast member.

Means for Solving the Problems

[0006] To achieve the above object, the present invention provides a precast member having, before being installed as a part of a building, a concrete main body, a wooden board disposed on the surface of the main body, a joining member that joins the main body and the wooden board with one end embedded in the main body and the other end embedded in the wooden board, and an elastic layer provided between the main body and the wooden board. Of the members constituting the exterior It is characterized by having such a structure in a state before being installed as a part of a building.

[0007] The precast member of the present invention has a structure in which a concrete main body and a wooden board on the surface of the main body are pre-mechanically joined by a joining member. By installing this as a part of a building, post-construction of the wooden board due to high-altitude work etc. becomes unnecessary. Therefore, the wooden board can be constructed safely and easily. Also, since an elastic layer is provided between the main body and the wooden board, long-term creep strain of the concrete, and displacement of the behavior between the main body and the wooden board due to temperature fluctuations, humidity fluctuations, etc. can be absorbed, and unnecessary stress can be prevented from occurring in the wooden board.

[0008] The precast member constitutes, for example, a balcony of a building, and the wooden board is disposed on the surface on the eaves lower side of the main body. In this case, a protruding portion protruding downward on the eaves side is provided at the end portion on the eaves tip side of the main body, and it is desirable that the wooden board be disposed with a gap between it and the protruding portion. If a balcony is formed with the precast member of the present invention, the wooden board can be easily constructed as an exterior finishing material for the eaves of the balcony. Also, by providing the above-mentioned protruding portion on the main body, the wooden board can be protected from rainwater and deterioration can be suppressed, and the design property is improved because the end face of the wooden board is hidden by the protruding portion. By disposing the wooden board with a gap between it and the protruding portion, it is possible to prevent the wooden board from coming into contact with the protruding portion due to the displacement of the behavior between the main body and the wooden board described above, and it is possible to prevent unnecessary stress from occurring in the wooden board.

[0009] It is desirable that the joining member does not protrude outside the precast member from the surface of the wooden board. Without penetrating, the wooden board This can prevent corrosion of the joining material etc., and prevent detachment due to deterioration of the joining member. Also, it is possible to prevent a decrease in design property due to the exposure of the joining member. This can prevent corrosion of the joining material, etc., and prevent detachment due to deterioration of the joining member. Also, it is possible to prevent a decrease in design property due to the exposure of the joining member.

[0010] The joining member has, for example, a pair of legs, and the pair of legs are embedded in the wooden board so as to be arranged in the fiber direction of the wooden board. In this case, it is desirable that the embedded portions of the pair of legs in the wooden board are bent toward each other's legs. By using the above joining member, the main body and the wooden board can be joined by a joining member having a simple structure. Further, by arranging the pair of legs so as to be arranged in the fiber direction of the wooden board, cracking of the wooden board caused by the joining member can be suppressed. Furthermore, by forming the embedded portion of the joining member in the wooden board into a bent shape as described above, the joining member can be firmly fixed to the wooden board.

[0011] It is desirable that the strip-shaped wooden boards are arranged side by side in the width direction of the wooden board, and convex portions and concave portions for fitting adjacent wooden boards are provided on respective opposing surfaces of adjacent wooden boards. By engaging adjacent wooden boards with each other by convex and concave portions, intrusion of moisture and the like from the boundary portion of the wooden boards can be prevented, and deterioration of the precast member from the boundary portion can be prevented. Also, the surface accuracy during wooden board construction is improved. Furthermore, by arranging a plurality of wooden boards side by side in the width direction, the individual wooden boards can be made narrower, and the deformation of the wooden boards can be reduced as compared with the case of arranging a single large wooden board.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide a precast member or the like that can safely and easily construct a wooden board on the surface of a precast member.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

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Figure 8

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0015] (1. Precast member 1) FIG. 1 is a view showing a precast member 1 according to an embodiment of the present invention. The precast member 1 is installed as a part of a building during the construction of the building, and FIG. 1 shows the state before being installed as a part of the building.

[0016] The precast member 1 of the present embodiment constitutes a balcony of a building such as a high-rise apartment building. FIG. 2 is a view showing a balcony 100 constructed using the precast member 1.

[0017] FIGS. 1 and 2 show a cross-section in the thickness direction of the precast member 1 (balcony 100) along the front-rear direction. The "front-rear direction" corresponds to the overhanging direction of the balcony 100 from the building, with the eaves side being "front" and the opposite side, i.e., the building interior side, being "rear". "Front" corresponds to the left side of FIGS. 1 and 2, and "rear" corresponds to the right side of FIGS. 1 and 2.

[0018] As shown in FIGS. 1 and 2, the precast member 1 has a main body 2, a wooden board 3, a joining member 4, an elastic layer 5, etc.

[0019] The main body 2 is a concrete member, and reinforcing bars are embedded inside it. In FIGS. 1 and 2, only some of the reinforcing bars 21 are illustrated as the reinforcing bars. One end of the reinforcing bar 21 is inserted into the front end of the cylindrical joint member 22. The joint member 22 is embedded in the rear end face of the main body 2. As shown in FIG. 2, the main reinforcing bars 201 of the building slab 200 are inserted into the rear end of the joint member 22. If there are no problems such as transportation, the joint member 22 can be omitted, and one end of the reinforcing bar 21 can be made to protrude from the rear end face of the main body 2 and used for joining with the slab 200.

[0020] Inside the concrete of the main body 2, a lightweight body 23 such as polystyrene foam, which has a lower density than the concrete of the main body 2, is also provided for the purpose of reducing the weight of the precast member 1. The lightweight body 23 is provided as needed and can also be omitted.

[0021] On the upper surface of the main body 2 that serves as the floor surface of the balcony 100, a drain groove 24 is provided. The groove 24 is provided at the front end of the main body 2 so as to extend in the width direction of the balcony 100. The width direction of the balcony 100 is a direction orthogonal to the cantilever direction of the balcony 100 in the plane and corresponds to the normal direction of the paper surface in FIGS. 1 and 2. The upper surface of the main body 2 has a gentle slope that becomes lower toward the groove 24. Further forward of the groove 24, attachment parts 25 such as sleeves and inserts for attaching handrails, waist walls, etc. are also provided. Note that the groove 24 may also be provided at the rear end of the main body 2. In this case as well, the upper surface of the main body 2 is provided with a gentle slope that becomes lower toward the groove 24 (at the rear end of the main body 2).

[0022] Also, on the lower surface of the main body 2 that serves as the eaves of the balcony 100 (the lower surface of the eaves), a protruding part 26 that protrudes downward is provided at the front side, that is, the eave tip side, of the main body 2.

[0023] The wooden board 3 is a strip-shaped board made of a wood material such as cedar, cypress, or oak, with its fiber direction being the longitudinal direction. The wooden board 3 is arranged on the lower surface of the main body 2 with its longitudinal direction being the front-rear direction and is used as an exterior finishing material for the precast member 1. In order to ensure durability and weather resistance, it is desirable that the wooden board 3 be subjected to heat treatment (carbonization) or antiseptic treatment. Heat treatment is superior to antiseptic treatment in terms of reducing the water absorption of the wooden board 3. A protective layer made of an oil-based paint or the like may be provided on the exposed surface of the wooden board 3 to the outside air to prevent dirt caused by wind and rain. If necessary, the wooden board 3 can also be made into a non-combustible treatment material impregnated with a flame retardant or the like.

[0024] The protruding portion 26 described above is arranged in front of the wooden board 3 to protect the wooden board 3 from rainwater. Also, by providing the protruding portion 26, the end face of the wooden board 3 is hidden when viewed from the outside of the building, so the design property is improved. The wooden board 3 is arranged with a gap 27 of about 20 mm, for example, between it and the protruding portion 26.

[0025] FIG. 3 is a view of a cross-section in the thickness direction near the wooden board 3 of the precast member 1 along the width direction of the balcony 100. As shown in FIG. 3, a plurality of wooden boards 3 are arranged side by side in their width direction. The width direction of the wooden board 3 is a direction orthogonal to the longitudinal direction of the wooden board 3 in a plane and corresponds to the left-right direction in FIG. 3.

[0026] Convex portions 32 and concave portions 33 are respectively provided on the opposing surfaces of adjacent wooden boards 3, and the convex portion 32 and the concave portion 33 on the opposing surfaces of adjacent wooden boards 3 are fitted together. By connecting the wooden boards 3 so that the convex portion 32 and the concave portion 33 engage with each other, it is possible to prevent moisture and the like from entering from the boundary portion between the wooden boards 3 and prevent deterioration of the precast member 1 from the boundary portion. Also, the surface accuracy during wooden board construction is improved.

[0027] The joining member 4 is a member that mechanically joins the main body 2 and the wooden board 3, with one end embedded in the main body 2 and the other end embedded in the wooden board 3. As shown in FIGS. 1 and 2, a plurality of joining members 4 are provided at intervals in the longitudinal direction of the wooden board 3. This interval is set in consideration of wind pressure resistance and the like through prior tests.

[0028] FIG. 4 is a view showing the joining member 4, and is a view of a cross-section in the thickness direction near the joining member 4 of the precast member 1 as seen along the front-rear direction. The joining member 4 is a mountain-shaped joining metal formed by bending a steel bar or the like, and has a pair of leg portions 41. The lower end portions (the other ends of the joining member 4) of these leg portions 41 are inserted into insertion holes 31 formed in the wooden board 3 and buried in the wooden board 3.

[0029] The buried portions 411 of the pair of leg portions 41 in the wooden board 3 are bent and inclined toward each other's leg portions 41. The insertion holes 31 also have an inclination corresponding to the buried portions 411. The insertion holes 31 are formed from the upper surface of the wooden board 3 but do not penetrate to the lower surface, so that the joining member 4 does not protrude from the surface of the wooden board 3 to the outside of the precast member 1.

[0030] As described above, the wooden board 3 is a strip-shaped plate material, and the fiber direction with high strength and difficult to deform is the longitudinal direction. The fiber direction of the wooden board 3 corresponds to the left-right direction in FIG. 4. The joining member 4 is arranged such that the pair of leg portions 41 are aligned in the fiber direction of the wooden board 3, and the lower end portions (buried portions 411) thereof are inserted into the wooden board 3. This is because the deformation of the wooden board 3 in the fiber direction is smaller than the deformation in the direction orthogonal to the fiber direction, and cracks or the like caused by the joining member 4 are less likely to occur.

[0031] The elastic layer 5 is an elastic layer provided between the main body 2 and the wooden board 3. The elastic layer 5 is formed, for example, by applying an elastic silicon-based adhesive to the wooden board 3 to a thickness of about 2 mm. The adhesive has waterproof properties, and the elastic layer 5 also has a water-stopping function.

[0032] The main body 2 is deformed by long-term creep strain of concrete, expansion and contraction due to temperature fluctuations, etc., and the wooden board 3 is deformed by expansion and contraction due to temperature fluctuations and humidity fluctuations, etc. These behaviors are different between the main body 2 and the wooden board 3. However, in this embodiment, by providing the elastic layer 5 between the main body 2 and the wooden board 3, the deviation in the behavior between the main body 2 and the wooden board 3 can be absorbed, and unnecessary stress can be prevented from occurring in the wooden board 3.

[0033] In this embodiment, a gap 27 is provided between the protruding portion 26 of the main body 2 and the wooden board 3, so that the wooden board 3 can be prevented from coming into contact with the protruding portion 26 due to the deviation in behavior between the main body 2 and the wooden board 3, and unnecessary stress can be prevented from being generated on the wooden board 3.

[0034] To construct the balcony 100, first, the precast member 1 prefabricated in a factory or the like in advance is transported to the construction site, lifted by a crane or the like, and installed at the position of the balcony 100. The precast member 1 is suspended and supported from the already constructed building body such as a pillar. At this time, a temporary lifting jig 300 (see FIG. 2) can be attached to the attachment portion 25 of the precast member 1 and used for supporting the precast member 1 by a suspension material 301 such as a wire. By suspending and supporting the precast member 1 from above, the shoring work on the side of the wooden board 3 becomes unnecessary, so damage to the wooden board 3 by the shoring work can be prevented.

[0035] After that, the reinforcement of the slab 200 of the building including the main reinforcement 201 is carried out, and the concrete of the slab 200 is placed, so that the precast member 1 is joined to the building body (slab 200).

[0036] (2. Manufacturing method of the precast member 1) When manufacturing the precast member 1, as shown in FIG. 5(a), the wooden board 3 is arranged in the formwork 6. The formwork 6 has a side portion 61 and a bottom portion 62. A plurality of wooden boards 3 are arranged side by side in their width direction (corresponding to the direction normal to the paper surface of FIG. 5(a)) and placed on the bottom portion 62. In this example, the bottom portion 62 is made of styrofoam, but a steel formwork may also be used. When using a steel formwork, a cushioning material can also be arranged on the bottom portion 62 to prevent the wooden board 3 from being damaged.

[0037] Thereafter, as shown in FIG. 5(b), a joining member 4 is attached to the wooden board 3. At this time, as described with reference to FIG. 4 and the like, the embedded portion 411 at the lower end of the leg portion 41 of the joining member 4 is inserted into the insertion hole 31 of the wooden board 3. If the joining member 4 is attached to the wooden board 3 in advance, space is required for storing the wooden board 3 with the joining member 4. However, as in this embodiment, by attaching the joining member 4 retroactively during the production of the precast member 1, the space required for storing the wooden board 3 can be reduced.

[0038] After attaching the joining member 4, as shown in FIG. 5(c), the above-mentioned adhesive is applied to the upper surface of the wooden board 3 to form the elastic layer 5. It is desirable to repeatedly apply the adhesive also to the boundary portions between adjacent wooden boards 3. Further, a gun-type sealing material 7 is applied along the outer periphery of the area where a plurality of wooden boards 3 are laid side by side to prevent seepage of the concrete from the outer periphery of the area to the lower surface side of the wooden board 3.

[0039] Thereafter, by arranging reinforcing bars such as reinforcing bars 21, joint members 22, lightweight bodies 23, etc. in the formwork 6 and placing concrete on the wooden board 3, the precast member 1 is manufactured. Since the elastic layer 5 has a water-stopping function as described above, during the production of the precast member 1, it is possible to prevent seepage of the concrete from the boundary portion between the wooden boards 3 and deterioration of the performance of the wooden board 3 due to moisture in the concrete.

[0040] As described above, the precast member 1 of this embodiment has a configuration in which the concrete main body 2 and the wooden board 3 on the surface of the main body are mechanically joined in advance by the joining member 4. By installing this as a part of a building, post-construction of the wooden board 3 due to work at heights etc. becomes unnecessary. Therefore, the wooden board 3 can be constructed safely and easily. Further, since the elastic layer 5 is provided between the main body 2 and the wooden board 3, it is possible to absorb the long-term creep strain of the concrete, the displacement of the behavior between the main body 2 and the wooden board 3 due to temperature fluctuations, humidity fluctuations, etc., and prevent the generation of unnecessary stress on the wooden board 3.

[0041] In this embodiment, the balcony 100 is formed using the precast member 1, and the wooden board 3 can be easily constructed as the exterior finishing material for the eaves of the balcony 100. When the wooden board 3 is post-constructed on the eaves, it is necessary to perform upward work on an unstable scaffold, but such work can be omitted in this embodiment.

[0042] Also, by providing a protruding portion 26 that protrudes downward under the eaves at the end of the eaves side of the main body 2, the wooden board 3 can be protected from rainwater and deterioration can be suppressed, and the design is improved because the end face of the wooden board 3 is hidden by the protruding portion 26. By arranging the wooden board 3 with a gap 27 between it and the protruding portion 26, it is possible to prevent the wooden board 3 from coming into contact with the protruding portion 26 due to the displacement of the behavior between the main body 2 and the wooden board 3 described above, and it is possible to prevent unnecessary stress from occurring in the wooden board 3.

[0043] The joining member 4 can join the main body 2 and the wooden board 3 with a simple structure by a pair of leg portions 41, and is excellent in durability and wind pressure resistance. These leg portions 41 are arranged so as to be aligned in the fiber direction of the wooden board 3, and cracking of the wooden board 3 caused by the joining member 4 can be suppressed. Furthermore, by forming the embedded portion 411 of the joining member 4 in the wooden board 3 into a bent shape as described above, the joining member 4 can be firmly fixed to the wooden board.

[0044] Also, since the joining member 4 does not expose from the surface of the wooden board 3 to the outside of the precast member 1, corrosion of the joining member 4 etc. can be prevented, and dropping due to deterioration of the joining member 4 can be prevented. Furthermore, a decrease in design due to the exposure of the joining member 4 can also be prevented.

[0045] In this embodiment, by engaging adjacent wooden boards 3 with each other by the convex portion 32 and the concave portion 33, intrusion of moisture etc. from the boundary portion of the wooden board 3 can be prevented, and deterioration of the precast member 1 from the boundary portion can be prevented. Also, the surface accuracy during wooden board construction is improved. Furthermore, by arranging a plurality of wooden boards 3 side by side in the width direction, the individual wooden boards 3 can be made narrower, and the deformation of the wooden boards 3 can be made smaller compared to the case where one large wooden board 3 is arranged.

[0046] However, the embodiments of the present invention are not limited to those described above. For example, the configuration and shape of the precast member 1 are not limited to those described with reference to FIG. 1 and the like. As an example, in some cases, a part of the concrete on the wooden board 3 may be cast on-site. In such a case, as shown in FIG. 6, the wooden board 3 is arranged to extend from the main body 2. In this example, due to reasons such as continuous casting of concrete from the beam of the building, a part of the concrete 400 on the rear side (inside the building side) is cast on-site. As the precast member 1a, a member in which the part of the concrete 400 is omitted is used with respect to the precast member 1 described above.

[0047] The wooden board 3 extends rearward from the remaining part of the main body 2. However, as it is, the extended part of the wooden board 3 is likely to be deformed by an external force or the like. Therefore, in the example of FIG. 6, a backing plate 8 is provided between the wooden board 3 and the main body 2 so as to straddle the boundary between the main body 2 and the concrete 400 to suppress the deformation of the extended part of the wooden board 3.

[0048] Also, in order to prevent the extended part of the wooden board 3 from being damaged during the transportation or hoisting of the precast member, as shown in FIG. 7, the concrete in a certain height range from the extended part of the wooden board 3 can be precast and made into a part of the main body 2, and on-site, the concrete 400 can be cast on top of the concrete. Thus, the concrete in a certain height range from the extended part of the wooden board 3 can be configured like a half-precast member and can be given a certain strength.

[0049] In addition, when providing an emergency escape opening on the floor of the balcony 100, an opening used as an emergency escape opening may be provided in the precast member 1. The allocation of the wooden board 3 is considered in consideration of the opening and set to avoid the opening.

[0050] In this embodiment, the longitudinal direction (fiber direction) of the strip-shaped wooden board 3 is aligned with the protruding direction of the balcony 100, and a plurality of wooden boards 3 are arranged side by side in the width direction. However, a plurality of wooden boards 3 may be arranged in the protruding direction of the balcony 100, or the longitudinal direction of the wooden board 3 may be aligned with the width direction of the balcony 100. The shape of each wooden board 3 is not particularly limited, and the convex portions 32 and concave portions 33 on the opposing surfaces of adjacent wooden boards 3 can also be omitted.

[0051] Also, in this embodiment, the joining member 4 is arranged such that the pair of leg portions 41 are aligned in the fiber direction of the wooden board 3, but the arrangement of the joining member 4 is not particularly limited. However, it is desirable that the pair of leg portions 41 are not arranged so as to straddle a plurality of wooden boards 3. This is because when the wooden board 3 deteriorates, it may be possible to replace them one by one. If the pair of leg portions 41 straddle a plurality of wooden boards 3, it will be difficult to replace these wooden boards one by one.

[0052] The shape of the joining member 4 is not limited to one having a pair of leg portions 41 as shown in FIG. 4, and any member that mechanically joins the main body 2 and the wooden board 3, that is, one end is embedded in the main body 2 and the other end is embedded in the wooden board 3, may be used. Also, if there are no problems with durability and weather resistance, the other end of the joining member 4 may be exposed outside the precast member 1 from the wooden board 3.

[0053] In this embodiment, a silicon-based adhesive having elasticity is used as the elastic layer 5, but other adhesives may also be used. Also, instead of an adhesive, an elastic sheet-like member may be used as the elastic layer 5. For exterior finishing materials such as tiles, adhesion by an adhesive is necessary. However, in this embodiment, since the main body 2 and the wooden board 3 are joined by the joining member 4, it is not essential to use an adhesive for the elastic layer 5.

[0054] Also, each of the precast members 1, 1a, and 1b described above constitutes the balcony 100 of the building, but the use of the precast member is not limited to this. For example, the precast member may be used as the eaves of the building. Also in this case, a precast member having substantially the same shape and configuration as the precast members 1, 1a, and 1b can be used, and the only difference is that the upper surface of the precast member is not used for walking by residents or the like.

[0055] Further, the precast member of the present invention having the main body 2, the wooden board 3, the joining member 4, and the elastic layer 5 can also be used when constructing a wall body such as a sleeve wall. FIG. 8 is a diagram schematically showing an example of the precast member 10 constituting the wall body. The wooden board 3 is provided on the vertical surface of the main body 2, and the main body 2 and the wooden board 3 are joined by a joining member (not shown) similar to the joining member 4 described above. An elastic layer 5 is also provided between the main body 2 and the wooden board 3. In addition, the precast member of the present invention is also applicable when constructing a column body. Also in this case, the wooden board 3 is joined to the vertical surface of the main body 2.

[0056] As described above, the preferred embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that those skilled in the art can conceive of various modification examples or correction examples within the scope of the technical idea disclosed in the present application, and it is naturally understood that those also belong to the technical scope of the present invention.

Explanation of Reference Numerals

[0057] 1, 1a, 1b, 10: Precast member 2: Main body 3: Wooden board 4: Joining member 5: Elastic layer 6: Formwork 21: Reinforcing bar 22: Joint member 23: Lightweight body 24: Groove 25: Mounting portion 26: Protrusion 31: Insertion hole 32: Convex portion 33: Concave portion 41: Leg portion 100: Balcony 411: Embedded part

Claims

1. The concrete body and A wooden board to be placed on the surface of the main body; a joining member for joining the main body and the wooden board, the joining member having one end embedded in the main body and the other end embedded in the wooden board; an elastic layer provided between the body and the wooden board; A precast component characterized by having the above in a state before being installed as part of a component constituting the exterior of a building.

2. 2. The precast member according to claim 1, wherein the precast member constitutes a balcony of a building, and the wooden board is arranged on the surface under the eaves of the main body.

3. A precast member as described in claim 2, characterized in that a protrusion that protrudes toward the eaves underside is provided at the eaves side end of the main body, and the wooden board is positioned with a gap between it and the protrusion.

4. 2. The precast member according to claim 1, wherein the joint members do not penetrate the wooden boards and are not exposed outside the precast member from the surface of the wooden boards.

5. The joining member has a pair of legs, The precast member according to claim 1, wherein the pair of legs are embedded in the wooden board so as to be aligned in the direction of the fibers of the wooden board.

6. 6. The precast member according to claim 5, wherein the portions of the pair of legs embedded in the wooden board are bent toward each other.

7. The strip-shaped wooden boards are arranged side by side in the width direction of the wooden boards, 2. The precast member according to claim 1, wherein a convex portion and a concave portion for fitting adjacent wooden boards together are provided on each of the opposing surfaces of the adjacent wooden boards.

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