JP2022182765A - Composite member and manufacturing method thereof - Google Patents

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

The present invention relates to a composite member of wood and reinforced concrete and a method for producing the same.

2. Description of the Related Art Conventionally, in a fire-resistant building, a column (a wooden structure column) using wood as a structural material bearing a long-term load is known. If a wooden structural column is used, the surface of the wooden structure must be covered with a fireproof covering material such as a gypsum board, which poses a problem that the structural wood cannot be exposed. Also, the refractory coating adds cost. There is also a method of covering the outside of the fireproof covering material with a finishing material made of wood to expose the wood as the finishing material, but this further increases the labor and cost of construction. In addition, since it is difficult to rigidly connect wooden structural columns, seismic elements must be planned separately.

On the other hand, for example, those described in Patent Documents 1 to 3 are known as fireproof coated steel members with wood.

JP 2013-011063 A JP 2019-056202 A JP-A-2000-017752

However, in the structures described in the conventional Patent Documents 1 to 3, wood is considered only as a fireproof covering material and a finishing material, and wood cannot be used as a structure. For this reason, there has been a demand for a synthetic member that has fire resistance and that can improve the strength of the member.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a synthetic member having fire resistance and improved member strength, and a method for manufacturing the same.

In order to solve the above-described problems and achieve the object, the composite member according to the present invention includes a reinforced concrete member that supports a long-term load and has fire resistance, and a reinforced concrete member that is provided in contact with the surface of the reinforced concrete member and supports the long-term load. A synthetic member comprising a non-supporting wooden member, further comprising a cotter provided on a surface of the wooden member on the side contacting the reinforced concrete member in order to integrate the reinforced concrete member and the wooden member, so that the wooden member is It is characterized by being used as a structure.

In addition, in the above-described invention, the synthetic member according to the present invention is provided on the side of the wooden member that is in contact with the reinforced concrete member in order to prevent the wooden member from buckling when stress is applied when a horizontal load is applied. It is characterized by further comprising a set screw.

Further, another synthetic member according to the present invention is characterized in that, in the above-mentioned invention, a fireproof coating is not required for the wooden member by adopting a mechanism in which the long-term load is supported only by the reinforced concrete member.

Further, a method for manufacturing a composite member according to the present invention is a method for manufacturing the above-described composite member, comprising the steps of assembling wooden members as forms for concrete, and placing concrete inside the wooden members to form reinforced concrete. The method is characterized by comprising a step of constructing the member.

A composite member according to the present invention is a composite member comprising a long-term load-bearing and fire-resistant reinforced concrete member and a wooden member provided in contact with the surface of the reinforced concrete member and not long-term load-bearing. , In order to integrate the reinforced concrete member and the wooden member, a cotter is provided on the surface of the wooden member that is in contact with the reinforced concrete member, so that the wooden member is used as a structural body. Even if there is no fireproof coating, it is possible to have fire resistance and to improve member strength.

Further, according to another composite member according to the present invention, in order to prevent buckling of the wooden member when stress is applied when a horizontal load is applied, the screw protrudes from the surface of the wooden member that is in contact with the reinforced concrete member. is further provided, it is possible to prevent buckling of the wooden member.

Further, according to another composite member according to the present invention, a fireproof coating is not required for the wood member by adopting a mechanism in which the long-term load is supported only by the reinforced concrete member. Since fireproof performance is not required for members that do not bear a long-term load, there is an effect that a fireproof coating can be made unnecessary for wooden members.

Further, according to a method for manufacturing a synthetic member according to the present invention, there is provided a method for manufacturing the above-described synthetic member, comprising the steps of assembling wooden members as forms for concrete, and pouring concrete inside the wooden members. Since it has a step of constructing a reinforced concrete member by means of the method, it has the effect that the composite member can be easily manufactured.

FIG. 1 is a diagram showing an embodiment of a synthetic member and a manufacturing method thereof according to the present invention, (1) is a cross-sectional view, (2) is a cross-sectional view along the line AA of (1), (3) is a cross-sectional view taken along line BB of (2). FIG. 2 is a diagram showing an example of a beam-to-column joint to which the present embodiment is applied, where (1) to (4) are for steel beams, and (5) to (8) are for RC beams. . FIG. 3 is a diagram showing another embodiment of the present invention. FIG. 4 is a diagram showing another embodiment of the present invention. FIG. 5 is an explanatory diagram of the action of the synthetic member, (1) is an explanatory diagram when bending stress is applied by horizontal load, (2) is an explanatory diagram of buckling prevention by screws, and (3) is an axial force transmission by a cotter. is an explanatory diagram of .

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a synthetic member and a method for manufacturing the same according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Synthetic member and manufacturing method thereof)
As shown in FIG. 1, a composite member 10 according to the embodiment of the present invention is a member used as a column, and is a reinforced concrete member 12 (hereinafter referred to as RC member) that supports a long-term load and has fire resistance. and a wooden member 14 provided in contact with the surface of the RC member 12 and not supporting a long-term load. A cotter 16 is provided on the surface of the wooden member 14 that is in contact with the RC member 12 .

The RC member 12 includes a concrete 18 having a rectangular (square) cross-section and a shaft shape, and main reinforcing bars 20 (reinforcing bars) and shear reinforcing bars 22 (reinforcing bars) arranged in the concrete 18 . The main reinforcements 20 are arranged in the direction of the column axis with intervals in the lateral direction, and the shear reinforcements 22 are arranged in an annular manner with intervals in the vertical direction.

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 . An end 24 of each plate is tapered at 45 degrees in cross section, and adjacent ends 24 are joined at this portion. Therefore, the overall cross-sectional shape of the synthetic member 10 is rectangular. For joining the ends 24, for example, an adhesive, a wooden structural screw, a lag screw, or other joining means can be used, but it is preferable to use a wooden structural screw in terms of workability. Laminated wood, CLT (Cross Laminated Timber), or the like can be used for the wooden member 14, for example. The wooden member 14 is used as a formwork for the concrete 18 of the RC member 12 and constructed integrally with the RC member 12 .

A cotter 16 is provided on the back side of the wooden member 14 to integrate the RC member 12 and the wooden member 14 . The cotter 16 is formed in a rectangular concave shape when viewed from the front, and a plurality of cotters 16 are provided at intervals in the vertical direction and the horizontal direction. Since the wooden member 14 is used as a formwork for the concrete 18 of the RC member 12, the concave shape of the cotter 16 is filled with the concrete 18 by placing concrete. By transmitting the axial force through the cotter 16, the bending stress of the composite member 10 can also be borne by the wooden member 14, and the yield strength is improved. In the example of FIG. 1(2), two rows of cotters 16 are arranged on the left and right portions of the back side of one wooden member 14, and the cotters 16 are formed in a rectangular concave shape when viewed from the front. However, the arrangement and shape of the cotter of the present invention are not limited to this. In the example of FIG. 1(1), the left-right direction (horizontal direction) is assumed to be the applied force direction F, and the effective length H is the length from the compression edge G at the right end to the position of the center of gravity of the tensile reinforcing bar.

When manufacturing this synthetic member 10, for example, first, the wooden member 14 is assembled as a formwork for concrete. Subsequently, the main reinforcing bars 20 and the shear reinforcing bars 22 are assembled in the area inside the wooden member 14 . After that, concrete 18 is placed inside the wooden member 14 to construct the RC member 12 . The wooden member 14 is constructed integrally as a formwork for the RC member 12, and is used as it is without being demolded from the RC member 12. - 特許庁Thereby, the synthetic member 10 can be manufactured easily.

According to the composite member 10 of the present embodiment, the RC member 12 that supports a long-term load and has fire resistance, and the wooden member 14 that is provided on the surface thereof via a cotter 16 and does not support a long-term load. In addition to having fire resistance, it is possible to improve member strength. Also, in a building that requires fire resistance performance, special fire resistance coating is not required by designing the allowable stress by bearing the long-term load only with the RC members 12 having fire resistance performance. Costs can be reduced by eliminating the need for a fireproof coating. Furthermore, it is possible to expose the wood of the structure without providing a fireproof coating. In addition, by using the formwork together with the finishing, it is possible to reduce the labor and cost of construction compared to ordinary wood finishing.

With respect to a horizontal load such as during an earthquake, the combined effect of the RC member 12 and the wooden member 14 improves the strength of the member. Building frame costs can be reduced by improving the seismic performance of members. In a building where fire resistance is not required, it is possible to design the wooden member 14 to bear a long-term load. Also, if it is confirmed in the secondary design that the wooden member 14 will not collapse, it is possible to design the structural calculation route 3 with the structural characteristic coefficient Ds equivalent to that of the RC structure. Furthermore, the environmental load can be reduced due to the effects of humidity control and air conditioning, which will be described later.

In the above embodiment, the case where the wooden member 14 and the RC member 12 are integrated by the cotter 16 has been described as an example, but the present invention is not limited to this. In addition to providing the cotter 16 on the back surface of the wooden member 14 , connection members such as screws may be provided on the back surface of the wooden member 14 at predetermined intervals so as to protrude toward the concrete of the RC member 12 . In this way, buckling of the wooden member 14 can be prevented by connecting members such as screws. In addition, since a connecting member such as a screw prevents a reduction in member yield strength, the combined use of the cotter 16 can further improve the member yield strength of the synthetic member 10 . A connecting member such as a screw may be provided inside the cotter 16 on the back side of the wooden member 14 or may be provided in a portion where the cotter 16 is not provided.

(Column beam joint)
Next, a column-to-beam joint where the synthetic member of the present embodiment is applied to a column will be described.
FIG. 2 is an example of a column-to-beam joint in which the composite member 10 of the present embodiment is applied to a column. (1) to (4) are steel beams, and (5) to (8) are beams is for RC (reinforced concrete) beams. (1) is a cross-sectional view along line AA of (2), (2) is a cross-sectional view along line BB of (1), and (3) is along line CC of (1). (4) is a cross-sectional view taken along line DD of (1). (5) is a cross-sectional view along the EE line of (6), (6) is a cross-sectional view along the FF line of (5), and (7) is along the GG line of (5). (8) is a cross-sectional view taken along line HH of (5).

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 beam-to-column joint portion 26 . The joint portion 28 is made of reinforced concrete in a substantially rectangular parallelepiped shape, and its upper and lower sides are continuous with the RC member 12 that constitutes the composite member 10 . Steel beams 30 made of H-shaped steel are connected to the joints 28 in the case of the steel beams shown in FIGS. On the other hand, RC beams 32 are connected to the connecting portions 28 in the case of the RC beams shown in FIGS. In such a configuration, in order to prevent the wooden member 14 from bearing a long-term load, a clearance is provided in the leg portion 34 at the lower end of the wooden member 14, and after the construction of the upper RC member 12 is completed, the clearance is provided. It is preferable to fill the clearance with non-shrinking mortar or the like. By doing so, the wooden member 14 does not bear a long-term load, so that the member's bearing strength is improved when a horizontal load is applied during an earthquake or the like.

In the case of the steel beams in FIGS. 2 (1) to (4) and in the case of the RC beams (5) to (8) in FIG. Only compressive stress is borne with respect to the load, not tensile stress. Assuming that the combined cross section of RC and wood is held flat, the member strength is improved by increasing the effective height H of the RC member 12 . In the plasticized region of the member, brittle fracture of the wooden member 14 does not occur unless the wooden member 14 reaches the ultimate yield strength. can be done.

The wooden member 14 is not mechanically joined at the beam-to-column joint 26 . In order to prevent damage and local deformation due to embedding of the corners of the wooden member 14 that act as compression edges when a horizontal load is applied, as shown in FIG. etc. to protect the compression end. By doing so, the toughness performance is improved without deterioration of yield strength during repeated loads due to earthquakes. The protective material 36 may be unnecessary if there is no concern about damage or local deformation due to embedding of the end portion due to the burden stress.

Also, as shown in FIG. 3(2), the edge cutting position of the wooden member 14 can be provided at the column center portion 38 instead of the joint portion 28 of the beam-to-column joint portion 26 . If the wooden member 14 is cut off near the reflex point of the central column 38, the protective material 36 for the wooden edge is not required.

FIGS. 3(3) to 3(6) show modifications of FIGS. 2(1) to 2(4). As shown in FIGS. 3(3) to 3(6), pull bolts 40 extending in the vertical direction are provided on the upper and lower wooden members 14 so as to straddle the beam-to-column joints 26, and the wooden members 14 that are vertically divided are connected to the pull bolts 40. 40 may be connected. By bearing the tensile stress with the pull bolt 40, the strength of the composite member 10 is further improved. However, it is preferable that the yield strength of the pull bolt 40 that receives the tensile stress is equal to or less than the tensile strength and the penetration strength of the wooden member 14, and that the design ensures toughness performance. The examples of FIGS. 3(3) to 3(6) are examples of fitting of the tension bolt 40 in the case of steel beams, but in the case of RC beams in FIGS. can be done. The design in this case can also be performed in the same manner as described above.

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 to this, and when the composite member is used as a beam member such as an RC beam or a steel beam is also applicable. By using the wooden member 14 as a compressive element in the beam member as well, the effective force of the member is increased and the strength of the member is improved.

(humidity control/air conditioning effect)
Next, the humidity control/air conditioning effect will be described.
Wood has a humidity control function that absorbs moisture inside when the surrounding humidity is high and releases the moisture inside into the air when it is dry. The surface of the wooden member 14 that represents the synthetic member 10 is subjected to uneven processing, or the wood subjected to uneven processing is attached to increase the surface area of the wood that is exposed to air, thereby maximizing the humidity conditioning effect of the wood. It is also possible to reduce the environmental load. FIG. 4 shows an example of unevenness processing applied to the surface of a wooden member. In addition, the thermal conductivity of wood is about 1/430 that of iron and about 1/12 that of concrete, so the use of thick wood can be expected to have the effect of softening indoor temperature changes.

(Member yield strength as a synthetic member)
Next, a supplementary description will be given of a method of designing the member yield strength of the composite member 10 described above.
FIG. 5(1) shows a stress intensity distribution diagram in the cross section when bending stress is applied by a horizontal load. When bending stress is applied only by a horizontal load, when comparing the stress intensity distributions of the composite member 10 and the case of the RC member 12 alone, in the case of the composite member 10, the wooden member 14 on the compression side is effective, so concrete and reinforcing bars are effective. Cσc ₁ <Cσc ₂ , T ₁ <T ₂ , and the acting stress becomes smaller.
however,
Cσc ₁ : Degree of compressive edge stress acting on the concrete of the composite member Cσc ₂ : Degree of compressive edge stress acting on the concrete of the RC member alone T ₁ : Tensile stress acting on the reinforcing bar of the composite member T ₂ : On the reinforcing bar of the RC member alone acting tensile stress

When the compressive edge stress Mσc acting on the wooden member 14 reaches the allowable compressive stress Mfc of the wooden member 14, the member yield strength of the composite member 10 is equal to the allowable compressive stress of concrete. Let the minimum value be the allowable bending moment Ma among the respective bending moments obtained when Cfc is reached or when the tensile reinforcing stress degree rσt reaches the allowable tensile stress degree rfc of the reinforcing bar. Regarding 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. It is desirable to check the following formula when calculating the cross section.
Mσc<Mfc, Cσc<Cfc, rσt<rft

(Prevention of buckling of wooden members receiving axial force)
Next, a supplementary description will be given of a design method for preventing buckling of the wooden member 14 that receives the axial force.
When an axial force is generated in a member as a frame when a horizontal load is applied, the wooden member 14 as the synthetic member 10 also bears the axial force. It is desirable to connect the wooden member 14 and the concrete with a connecting member such as a wooden structural screw or a lag screw so that the allowable compressive stress of the wooden member 14 is not exceeded.

The calculation formula for the wooden member 14 that receives the compressive force is based on the following formula according to the wooden structure design standard and its commentary.
σc≦ηfc
However, when λ≤30, η=1, when 30<λ≤100, η=1.3-0.01λ, and when 100<λ, η=3000/ ^λ2.
λ=lk/i
σc: Compressive edge stress acting on the wooden member, fc: Allowable compressive stress of the wooden member, η: Buckling reduction factor determined according to the slenderness ratio of the member, λ: Slenderness ratio, i: Cross-sectional secondary radius in the buckling direction

FIG. 5(2) shows a method of joining concrete and wood for restraining the wooden member 14 from buckling.
The buckling length lk is set to the interval between the wooden structural screws or the like by joining the concrete with the wooden structural screws or the like. In order to obtain an effective buckling length lk, the force P (2% of the compressive strength of the wooden member) generated in the buckling direction must be met by the cone breaking resistance Ta1 of the concrete part and the tension of the cross-sectional area such as the screw for wooden structure The condition is that the yield strength Ta2 and the pull-out yield strength Ta3 of the wooden structural screw or the like to the tree are large.

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

(Axial force transmission by cotter)
Next, a supplementary description will be given of a design method for axial force transmission by the cotter 16. FIG.
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 on the wooden member 14 . FIG. 5(3) shows a joint between wood and concrete by the cotter 16. As shown in FIG. In order to integrate the RC member 12 and the wooden member 14, it is a condition that the stress Mσc generated in the cotter lower portion (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 obtained by the following formula from the stress Cσc generated at the concrete compression edge due to the cotter interval x and the horizontal load.

Mfc≦Mσc
=Cσc x/MA

When the cotter 16 and the wooden structural screw for preventing the buckling of the wooden member 14 are used together, the wooden structural screw obtained by the above calculation is placed in the area having the cotter 16 as shown in FIG. 5(3). are arranged at the required pitch.

As described above, according to the composite member according to the present invention, 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, the composite member further includes a cotter provided on the surface of the wooden member that is in contact with the reinforced concrete member, so that the wooden member can be used as a structure. Therefore, even if the synthetic member does not have a fireproof coating, it can have fire resistance and can improve member yield strength.

Further, according to another composite member according to the present invention, in order to prevent buckling of the wooden member when stress is applied when a horizontal load is applied, the screw protrudes from the surface of the wooden member that is in contact with the reinforced concrete member. is further provided, it is possible to prevent buckling of the wooden member.

Further, according to another composite member according to the present invention, a fireproof coating is not required for the wood member by adopting a mechanism in which the long-term load is supported only by the reinforced concrete member. Since fireproof performance is not required for members that do not bear a long-term load, it is possible to eliminate the need for a fireproof coating for wooden members.

Further, according to a method for manufacturing a synthetic member according to the present invention, there is provided a method for manufacturing the above-described synthetic member, comprising the steps of assembling wooden members as forms for concrete, and pouring concrete inside the wooden members. Composite members can be easily manufactured since the step of constructing the reinforced concrete members is carried out by means of a process.

INDUSTRIAL APPLICABILITY As described above, the synthetic member and the method for manufacturing the same according to the present invention are useful for fire-resistant buildings, and are particularly suitable for obtaining a synthetic member with improved member strength.

10 synthetic member 12 reinforced concrete member 14 wooden member 16 cotter 18 concrete 20 main bar (rebar)
22 Shear reinforcing bars (reinforcing bars)
24 end portion 26 column beam joint portion 28 joint portion 30 steel frame beam 32 RC beam 34 leg portion 36 protective material 38 column central portion 40 tension bolt

Claims (4)

A composite member comprising a long-term load-bearing and fire-resistant reinforced concrete member and a wooden member provided in contact with the surface of the reinforced concrete member and not long-term load-bearing,
In order to integrate the reinforced concrete member and the wooden member, a cotter is further provided on the surface of the wooden member that is in contact with the reinforced concrete member, thereby using the wooden member as a structure. Element. 2. The wooden member according to claim 1, further comprising a screw protruding from a surface of the wooden member which is in contact with the reinforced concrete member in order to prevent buckling of the wooden member when stress is applied when a horizontal load is applied. synthetic material. 3. The synthetic member according to claim 1 or 2, characterized in that a fireproof coating is not required for the wood member by adopting a mechanism in which a long-term load is supported only by the reinforced concrete member. A method for manufacturing a synthetic member according to any one of claims 1 to 3,
1. A method of manufacturing a composite member, comprising the steps of assembling a wooden member as a formwork for concrete, and placing concrete inside the wooden member to construct a reinforced concrete member.

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