Synthetic member and method for manufacturing the same

Abstract

To provide a composite member capable of improving member yield strength while having fire resistance and a manufacturing method of the same.SOLUTION: A composite member 10 comprises a reinforcement concrete member 12 having fire resistance while supporting a sustained loading and a wooden member 14 provided in contact with a surface of the reinforcement concrete member 12 while not supporting the sustained loading and further comprises a cotter 16 provided on a surface of a side in contact with the reinforcement concrete member 12 of the wooden member 14 to integrate the reinforcement concrete member 12 with the wooden member 14. A machine screw projecting on a surface in contact with the reinforcement member 12 of the wooden member 14 may be further provided to prevent a buckling of the wooden member 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a composite member of wood and reinforced concrete and a method for manufacturing the same.

Background Art

[0002] Conventionally, in fire-resistant buildings, columns (wooden structural columns) using wood as structural members that bear long-term loads are known. When adopting wooden structural columns, it is necessary to cover the surface of the wood with a fire-resistant coating material such as gypsum board, and there is a problem that the structural wood cannot be shown. In addition, the cost increases due to this fire-resistant coating. There is also a method of covering the outside of the fire-resistant coating material with a finishing material made of wood and showing the wood as the finishing material, but the construction labor and cost further increase. Further, since it is difficult to make the joints of the wooden structural columns rigid joints, it is necessary to separately plan earthquake-resistant elements.

[0003] On the other hand, as a member in which a steel frame member is fire-resistant coated with wood, for example, those described in Patent Documents 1 to 3 are known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the structures described in the above-mentioned conventional Patent Documents 1 to 3, wood is only considered as a fire-resistant coating material and a finishing material, and wood cannot be used as a structural body. For this reason, there has been a demand for a composite member that has fire resistance and can improve the member strength.

[0006] The present invention has been made in view of the above, and an object thereof is to provide a composite member having fire resistance and capable of improving the member strength, and a method for manufacturing the same.

Means for Solving the Problems

[0007] In order to solve the above-described problems and achieve the object, a composite member according to the present invention includes a reinforced concrete member that supports a long-term load and has fire resistance, and a wooden member that is provided in contact with the surface of the reinforced concrete member and does not support a long-term load. The composite member further includes a cotter provided on the surface of the wooden member in contact with the reinforced concrete member in order to integrate the reinforced concrete member and the wooden member, and is characterized in that the wooden member is used as a structure.

[0008] Another composite member according to the present invention is characterized in that, in the above-described invention, in order to prevent buckling during stress bearing when a horizontal load acts on the wooden member, it further includes a screw protruding from the surface of the wooden member in contact with the reinforced concrete member.

[0009] Another composite member according to the present invention is characterized in that, in the above-described invention, a mechanism for supporting a long-term load only by the reinforced concrete member is adopted, so that a fireproof coating is not required for the wooden member.

[0010] A method for manufacturing a composite member according to the present invention is a method for manufacturing the above-described composite member, and includes a step of assembling a wooden member as a formwork for concrete, and a step of placing concrete inside the wooden member to construct a reinforced concrete member.

Effects of the Invention

[0011] According to the composite member of the present invention, there is provided a composite member including a reinforced concrete member that supports long-term loads and has fire resistance, and a wooden member that is provided in contact with the surface of the reinforced concrete member and does not support long-term loads. In order to integrate the reinforced concrete member and the wooden member, a cotter provided on the surface of the wooden member in contact with the reinforced concrete member is further provided, so that the wooden member is used as a structure. Therefore, even without a fire-resistant coating as a composite member, it has fire resistance and can improve the member strength.

[0012] Further, according to another composite member of the present invention, in order to prevent buckling during stress bearing when a horizontal load acts on the wooden member, a screw protruding from the surface of the wooden member in contact with the reinforced concrete member is further provided, so that buckling of the wooden member can be prevented.

[0013] Also, according to another composite member of the present invention, by adopting a mechanism in which long-term loads are supported only by the reinforced concrete member, a fire-resistant coating is not required for the wooden member. Since fire resistance performance is not required for members that do not bear long-term loads, a fire-resistant coating can be dispensed with for the wooden member.

[0014] Further, according to the manufacturing method of the composite member of the present invention, it is a method for manufacturing the above-described composite member, and includes a step of assembling a wooden member as a formwork for concrete, and a step of placing concrete inside the wooden member to construct a reinforced concrete member. Therefore, the composite member can be easily manufactured.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the composite member and its manufacturing method according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited by this embodiment.

[0017] (Composite Member and Its Manufacturing Method) As shown in FIG. 1, a composite member 10 according to an embodiment of the present invention is a member used as a column, and includes a reinforced concrete member 12 (hereinafter referred to as an RC member) that supports a long-term load and has fire resistance, and a wooden member 14 that is provided in contact with the surface of the RC member 12 and does not support a long-term load. A cotter 16 is provided on the surface of the wooden member 14 that contacts the RC member 12.

[0018] The RC member 12 includes column-axis-shaped concrete 18 having a rectangular (square) cross section, main reinforcement bars 20 (steel bars) and shear reinforcement bars 22 (steel bars) arranged in the concrete 18. The main reinforcement bars 20 are arranged in the column axis direction at intervals in the horizontal direction, and the shear reinforcement bars 22 are arranged annularly at intervals in the vertical direction.

[0019] The wooden member 14 is composed of four plates that are arranged in contact with the front, rear, left, and right surfaces of the RC member 12. The end portions 24 of each plate are tapered at an angle of 45 degrees in a cross-sectional view, and the adjacent end portions 24 are joined at this part. For this reason, the cross-sectional shape of the entire composite member 10 is rectangular. In addition, for joining the end portions 24 to each other, joining means such as an adhesive, a wood structure screw, or a lag screw can be used, but it is preferable to use a wood structure screw from the viewpoint of workability. For the wooden member 14, for example, glued laminated timber or CLT (Cross Laminated Timber) can be used. The wooden member 14 is used as a formwork for the concrete 18 of the RC member 12 and is constructed integrally with the RC member 12.

[0020] The cotter 16 is provided on the back surface side of the wooden member 14 in order to integrate the RC member 12 and the wooden member 14. The cotter 16 is formed in a rectangular concave shape in a front view, and a plurality of cotters 16 are provided at intervals in the vertical direction and the horizontal direction, respectively. Since the wooden member 14 is used as a formwork for the concrete 18 of the RC member 12, the concrete 18 will be filled inside the concave shape of the cotter 16 by placing the concrete. By transmitting the axial force by the cotter 16, the bending stress can also be borne by the wooden member 14 part as the composite member 10, and the load-bearing capacity is improved. In the example of Fig. 1(2), a case is shown where two rows of cotters 16 are arranged on the left and right portions on the back surface side of one wooden member 14, and the cotter 16 is formed in a rectangular concave shape in a front view. However, the arrangement and shape of the cotter of the present invention are not limited to this. In addition, in the example of Fig. 1(1), the horizontal direction (lateral direction) is the assumed loading direction F, and the length from the compression edge G at the right end to the centroid position of the tension reinforcement is the effective depth H.

[0021] When manufacturing this composite member 10, for example, first assemble the wooden member 14 as a formwork for concrete. Subsequently, assemble the main reinforcement bars 20 and shear reinforcement bars 22 in the inner region of the wooden member 14. Thereafter, place the concrete 18 inside the wooden member 14 to construct the RC member 12. The wooden member 14 is integrally constructed as a formwork for the RC member 12 and is used as it is without being demolded from the RC member 12. Thereby, the composite member 10 can be easily manufactured.

[0022] According to the composite member 10 of the present embodiment, since it is composed of the RC member 12 that supports long-term loads and has fire resistance, and the wooden member 14 that is provided via the cotter 16 on its surface and does not support long-term loads, it has fire resistance and can improve the member load-bearing capacity. Also, in a building where fire resistance performance is required, by having only the RC member 12 with fire resistance performance bear the long-term load and performing the allowable stress design, no special fire protection coating is required. Since the fire protection coating is not needed, the cost can be reduced. Furthermore, it is possible to expose the wood of the structure without providing a fire protection coating. Also, by using a formwork combination finish, the construction labor and cost can be reduced compared to ordinary wood finishes.

[0023] For horizontal loads during an earthquake or the like, the member load-bearing capacity is improved by the composite effect of the RC member 12 and the wooden member 14. By improving the seismic performance of the members, the frame cost can be reduced. In a building where fire resistance performance is not required, it is also possible to design by having the wooden member 14 bear the long-term load. Also, in the secondary design, if it is confirmed that the wooden member 14 does not crush, a structural calculation route 3 with a structural characteristic coefficient Ds equivalent to that of an RC structure can be designed. Furthermore, the environmental load can be reduced by the humidity control and air conditioning effects as described later.

[0024] In the above-described embodiment, the case where the integrator 16 is used to integrate the wooden member 14 and the RC member 12 has been described as an example, but the present invention is not limited thereto. In addition to providing the integrator 16 on the back surface of the wooden member 14, connecting members such as screws may be projected toward the concrete of the RC member 12 at predetermined intervals on the back surface of the wooden member 14. By doing so, buckling of the wooden member 14 can be prevented by the connecting members such as screws. Further, since reduction of the member strength is prevented by the connecting members such as screws, the member strength of the composite member 10 can be further improved by using them in combination with the integrator 16. The connecting members such as screws may be provided inside the integrator 16 on the back surface side of the wooden member 14, or may be provided at a portion where there is no integrator 16.

[0025] (Column-beam joint) Next, the column-beam joint to which the composite member of the present embodiment is applied to a column will be described. FIG. 2 is an example of a column-beam joint to which the composite member 10 of the present embodiment is applied to a column. (1) to (4) show the case where the beam is a steel beam, and (5) to (8) show the case where the beam is an RC (reinforced concrete) beam. (1) is a cross-sectional view taken along line A-A of (2), (2) is a cross-sectional view taken along line B-B of (1), (3) is a cross-sectional view taken along line C-C of (1), and (4) is a cross-sectional view taken along line D-D of (1). (5) is a cross-sectional view taken along line E-E of (6), (6) is a cross-sectional view taken along line F-F of (5), (7) is a cross-sectional view taken along line G-G of (5), and (8) is a cross-sectional view taken along line H-H of (5).

[0026] As shown in Fig. 2, the wooden member 14 that constitutes the composite member 10 is vertically divided at the joint portion 28 of the column-beam joint 26. The joint portion 28 is made of reinforced concrete in a substantially rectangular parallelepiped shape, and its upper and lower parts are continuous with the RC member 12 that constitutes the composite member 10. In the case of the joint portion 28 in the steel beam shown in Figs. 2(1) to (4), steel beams 30 made of H-shaped steel are connected from the four directions of front, back, left, and right. On the other hand, in the case of the joint portion 28 in the RC beam shown in Figs. 2(5) to (8), RC beams 32 are connected from the four directions of front, back, left, and right. In such a configuration, in order to prevent the wooden member 14 from bearing the long-term load, a clearance is provided at the leg portion 34 at the lower end of the wooden member 14, and it is preferable to fill the clearance with non-shrink mortar or the like after the completion of the frame construction of the upper RC member 12 during construction. By doing so, since the wooden member 14 does not bear the long-term load, the member strength during the action of horizontal loads such as during an earthquake is improved.

[0027] In the case of the steel beam in Figs. 2(1) to (4) and the case of the RC beam in (5) to (8), in either case, since the wooden member 14 is divided at the column-beam joint 26, it does not bear the tensile stress but only bears the compressive stress against the horizontal load. Assuming the planar retention of the composite cross-section of RC and wood, the effective flexural rigidity H of the RC member 12 increases, thereby improving the member strength. In the plasticized region of the member, as long as the wooden member 14 has not reached the ultimate strength, brittle fracture of the wooden member 14 does not occur, so in the secondary design, a structural characteristic coefficient Ds equivalent to that of RC construction can be adopted for design.

[0028] The wooden member 14 is not mechanically joined at the column-beam joint 26. In order to prevent damage and local deformation due to the indentation of the corner of the wooden member 14 that becomes the compression edge during horizontal loads, as shown in Fig. 3(1), a protective material 36 such as an angle material is attached to the edge of the lower end of the wooden member 14 with screws or the like to protect the compression end. By doing so, deterioration of strength does not occur during repeated loads due to an earthquake, and the toughness performance is improved. When damage and local deformation due to indentation at the end are not a concern due to the applied stress, the protective material 36 can also be omitted.

[0029] Also, as shown in Fig. 3(2), the edge cutting position of the wooden member 14 can also be provided at the central part 38 of the column instead of the joint part 28 of the column and beam. When the edge cutting of the wooden member 14 is provided near the inflection point of the central part 38 of the column, the protective material 36 for the wooden edge part is unnecessary.

[0030] Figs. 3(3) to (6) show modified examples of Figs. 2(1) to (4). As shown in Figs. 3(3) to (6), tension bolts 40 extending in the vertical direction in a manner straddling the column-beam joint 26 may be provided on the upper and lower wooden members 14, and the wooden members 14 divided vertically may be connected by the tension bolts 40. By having the tension bolts 40 bear the tensile stress, the load-bearing capacity of the composite member 10 is further improved. However, the yield strength of the tension bolts 40 that receive the tensile stress should be equal to or less than the tensile strength and the embedment strength of the wooden member 14, and it is preferable to adopt a design that ensures the toughness performance. The examples in Figs. 3(3) to (6) are examples of the accommodation of the tension bolts 40 in the case of a steel beam, but the tension bolts 40 can also be provided in the same manner in the case of the RC beams in Figs. 2(5) to (8). The design in this case can also be carried out in the same manner as described above.

[0031] In the above embodiment, the case where the composite member 10 is used as a column member has been described as an example, but the present invention is not limited thereto, and it is similarly applicable when the composite member is used as a beam member such as an RC beam or a steel beam. Also in the beam member, by making the wooden member 14 act as a compression element, the effective cross-sectional area of the member increases and the member load-bearing capacity improves.

[0032] (Humidity control and air conditioning effect) Next, the humidity control and air conditioning effect will be described. Wood has a humidity control function of absorbing moisture inside when the surrounding humidity is high and releasing the internal moisture into the air when it is dry. By applying uneven processing to the surface of the wood member 14 that represents the synthetic member 10, or by attaching wood with uneven processing, it is possible to maximize the humidity control effect of the wood by increasing the surface area where the wood touches the air and reduce the indoor environmental load. Fig. 4 shows an example of the uneven processing applied to the surface of the wood member. Also, the thermal conductivity of wood is about 1 / 430 of iron and about 1 / 12 of concrete, and by using thick wood, an effect of moderating the temperature change inside the room can also be expected.

[0033] (Member strength as a synthetic member) Next, a supplementary explanation will be given about the design method of the member strength as the above synthetic member 10. Fig. 5(1) shows the stress distribution diagram within the cross-section when a bending stress acts due to a horizontal load. When comparing the stress distributions in the case of the synthetic member 10 and the case of the RC member 12 alone when a bending stress acts only due to a horizontal load, in the case of the synthetic member 10, since the wood member 14 on the compression side becomes effective, for the stress acting on the concrete and the steel bars, Cσc 1 <Cσc 2 、T 1 <T 2 and the acting stress becomes small. However, Cσc 1 : Compressive edge stress acting on the concrete of the synthetic member Cσc 2 : Compressive edge stress acting on the concrete of the RC member alone T 1 : Tensile stress acting on the steel bars of the synthetic member T 2 : Tensile stress acting on the steel bars of the RC member alone

[0034] The member strength of the composite member 10 is determined as the minimum value among the respective bending moments obtained when the compressive edge stress Mσc acting on the wooden member 14 reaches the allowable compressive stress Mfc of the wooden member 14, when the compressive edge stress Cσc acting on the concrete reaches the allowable compressive stress Cfc of the concrete, or when the tensile reinforcement stress rσt reaches the allowable tensile stress rfc of the reinforcement. For the axial force, the long-term axial force is borne by the RC section, the compressive force generated by the horizontal load is borne by the entire section, and the tensile force is borne by the RC section. When calculating the section, it is desirable to check the following formula. Mσc < Mfc, Cσc < Cfc, rσt < rft

[0035] (Prevention of buckling of wooden members under axial force) Next, a supplementary explanation will be given on the design method for preventing the buckling of the wooden member 14 under axial force. When an axial force is generated in the member as a frame under horizontal load, the wooden member 14 also bears the axial force as the composite member 10. It is desirable to connect the wooden member 14 and the concrete with a connecting member such as a wood structure screw or a lag screw so as not to exceed the allowable compressive stress of the wooden member 14.

[0036] The calculation formula for the wooden member 14 under compressive force is as follows according to the wooden structure design standard and its explanatory notes. σc ≦ ηfc However, when λ ≦ 30, η = 1; when 30 < λ ≦ 100, η = 1.3 - 0.01λ; when 100 < λ, η = 3000 / λ 2 λ = lk / i σc: Compressive edge stress acting on the wooden member, fc: Allowable compressive stress of the wooden member η: Buckling reduction coefficient determined according to the slenderness ratio of the material, λ: Slenderness ratio i: Second moment of area radius in the buckling direction

[0037] The joining method of concrete and wood for restraining the buckling of the wooden member 14 is shown in Fig. 5(2). By joining with concrete via screws for wooden structures etc., the interval between the screws for wooden structures etc. is set to the buckling length lk. In order to obtain an effective buckling length lk, it is a condition that the cone fracture resistance Ta1 of the concrete part, the tensile resistance Ta2 of the cross-sectional area of the screws for wooden structures etc. and the pull-out resistance Ta3 of the screws for wooden structures etc. against the wood are greater than the force P (2% of the compressive bearing capacity of the wooden member) generated in the buckling direction.

[0038] P = 0.02A·fc (A: cross-sectional area of wooden member, fc: allowable compressive stress of wooden member) P < Ta1 = Σ2dπ·fs (fs: shear resistance of concrete, d: protruding length of screws for wooden structures etc.) P < Ta2 = ΣAs·ft (As: effective cross-sectional area of screws for wooden structures etc., ft: allowable tensile stress of screws for wooden structures etc.) P < Ta3 = Σpa (according to the wooden structure design standard and its commentary)

[0039] (Axial force transmission by cotter) Next, a supplementary explanation will be given regarding the design method for axial force transmission by the cotter 16. In order to integrate the RC member 12 and the wooden member 14, the stress generated in the RC member 12 is transmitted through the cotter 16 provided in the wooden member 14. The joint part by the cotter 16 between the wood and the concrete is shown in Fig. 5(3). In order to integrate the RC member 12 and the wooden member 14, it is a condition that the stress Mσc generated at the lower part of the cotter (cotter lower area MA) is equal to or less than the allowable compressive stress Mfc of the wooden member 14. The stress Mσc generated at the lower part of the cotter is given by the following formula from the stress Cσc generated at the compression edge of the concrete due to the cotter interval x and the horizontal load.

[0040] Mfc ≦ Mσc = Cσc·x / MA

[0041] When the cotter 16 and the screws for wooden structures for preventing buckling of the wooden member 14 are used in combination, the screws for wooden structures obtained by the above calculation are arranged at the required pitch in the area having the cotter 16 as shown in Fig. 5(3).

[0042] As described above, according to the composite member of the present invention, there is provided a composite member including a reinforced concrete member that supports a long-term load and has fire resistance, and a wooden member that is provided in contact with the surface of the reinforced concrete member and does not support a long-term load. In order to integrate the reinforced concrete member and the wooden member, by further providing a cotter provided on the surface of the wooden member in contact with the reinforced concrete member, since the wooden member is used as a structure, even without a fireproof coating as a composite member, it has fire resistance and can improve the member strength.

[0043] Further, according to another composite member of the present invention, in order to prevent buckling during stress bearing when a horizontal load acts on the wooden member, by further providing a screw protruding from the surface of the wooden member in contact with the reinforced concrete member, buckling of the wooden member can be prevented.

[0044] Further, according to another composite member of the present invention, by adopting a mechanism in which a long-term load is supported only by the reinforced concrete member, a fireproof coating is not required for the wooden member. Since fire resistance performance is not required for a member that does not bear a long-term load, a fireproof coating can be dispensed with for the wooden member.

[0045] Further, according to the manufacturing method of the composite member of the present invention, which is a method for manufacturing the above-described composite member, it includes a step of assembling a wooden member as a formwork for concrete, and a step of placing concrete inside the wooden member to construct a reinforced concrete member, so that the composite member can be easily manufactured.

Industrial Applicability

[0046] As described above, the composite member and its manufacturing method according to the present invention are useful for fireproof buildings, and in particular, are suitable for obtaining a composite member with improved member strength.

Explanation of Signs

[0047] 10 Composite member 12 Reinforced concrete member 14 Wooden member 16 Cotter 18 Concrete 20 Main reinforcement bar (steel bar) 22 Shear reinforcement bar (steel bar) 24 End part 26 Column-beam joint 28 Joint part 30 Steel frame beam 32 RC beam 34 Leg part 36 Protective material 38 Central part of column 40 Pull bolt

Claims

1. A composite member used as a column, comprising a reinforced concrete member that supports long-term loads and has fire resistance, and a wooden member provided in contact with the front, rear, left, and right surfaces of the reinforced concrete member and not supporting long-term loads. In order to integrate the reinforced concrete member and the wooden member, the composite member further includes a cotter provided on the surface of the wooden member in contact with the reinforced concrete member, thereby utilizing the wooden member as a structural body. The composite member is characterized in that the wooden member is vertically divided at the joint of the column-beam joint where the beam is connected to the column.

2. The composite member according to claim 1, further comprising screws protruding from the surface of the wooden member in contact with the reinforced concrete member in order to prevent buckling during stress bearing when a horizontal load acts on the wooden member.

3. The composite member according to claim 1 or 2, characterized in that a mechanism is provided to support long-term loads only by the reinforced concrete member, so that a fireproof coating is not required for the wooden member.

4. A method for manufacturing the composite member according to any one of claims 1 to 3, characterized by comprising a step of assembling the wooden member as a formwork for concrete, and a step of placing concrete inside the wooden member to construct the reinforced concrete member.

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