Fire-resistant structure of column-beam joints

Abstract

To provide a fire-resistant structure for column-beam joints that can ensure fire resistance equivalent to that of columns and beams. [Solution] A fire-resistant column-beam joint structure 100 is formed by joining a fire-resistant wooden column 12 and a fire-resistant wooden beam 14 via a T-shaped cross-section joining hardware 16, which consists of a gusset plate 50 fixed to a plate 36 protruding from the side end of the core material 26 of the fire-resistant wooden beam 14 toward the fire-resistant wooden column 12, and a base plate 52 attached to the side surface of the core material 20 of the fire-resistant wooden column 12, wherein a cement-based solidifying material 18 is filled in the area around the joining hardware 16 between the side end of the fire-resistant wooden beam 14 and the side surface of the fire-resistant wooden column 12. A fire-resistant coating material or a wood coating material may be provided on the outside of the cement-based solidifying material 18. A fire-resistant coating material may be provided on the end face of the beam.

Description

[Technical Field]

[0001] The present invention relates to a fire-resistant structure for a beam-column joint. [Background Art]

[0002] Conventionally, the applicant of the present patent has developed fire-resistant wooden columns and beams (Slim Fire-Resistant Wood (registered trademark)) that ensure 1-hour or 2-hour fire resistance by performing fire-resistant coating on load-supporting wood with reinforced gypsum boards and fire-resistant sheets (see, for example, Patent Document 1). On the other hand, although specifications for beam-column joints are not defined, if the structural performance around the joint decreases due to fire heating, there is a risk of leading to building collapse, so beam-column joints are also required to have the same fire resistance performance as columns and beams.

[0003] As conventional fire-resistant structures for beam-column joints, those described in Patent Documents 2 and 3 are known, for example. Patent Document 2 discloses a joint between a wooden column and a steel beam, in which high-density wood or flame-retardant treated wood is coated as a burn allowance. Patent Document 3 discloses a structure in which grout material is filled around a steel joint member that joins a wooden column and a concrete member. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent No. 6414670 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2018-3475 [Patent Document 3] Japanese Unexamined Patent Application Publication No. 2022-19358 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] Incidentally, joining metal hardware such as gusset plates are often used for joints between fire-resistant wooden columns and beams. The following problems arise when ensuring the fire resistance performance of such joints.

[0006] • The temperature of the steel in the connecting hardware exceeds the allowable temperature (average 350°C, maximum 450°C), causing failure. • Heat conduction from the connecting hardware causes the wood, which is the load-bearing member, to carbonize. • Gaps form in the joints between materials, allowing heat to enter and carbonize the wood, which is the load-bearing member.

[0007] Therefore, there was a need to develop a structure that could ensure fire resistance equivalent to that of fire-resistant wooden columns and beams alone, even in column-beam joints using connecting hardware.

[0008] The present invention has been made in view of the above, and aims to provide a fire-resistant structure for a column-beam joint that can ensure fire resistance equivalent to that of a column-beam joint. [Means for solving the problem]

[0009] To solve the above-mentioned problems and achieve the objective, the fire-resistant structure for a column-beam joint according to the present invention is a fire-resistant structure for a column-beam joint comprising a fire-resistant wooden column comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, and a fire-resistant wooden beam comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, joined via a T-shaped connecting fitting consisting of a gusset plate fixed to a plate protruding from the side end of the core material of the fire-resistant wooden beam toward the fire-resistant wooden column, and a base plate attached to the side surface of the core material of the fire-resistant wooden column, wherein the structure is characterized by comprising a cement-based solidifying material filled in the area around the connecting fitting between the side end of the fire-resistant wooden beam and the side surface of the fire-resistant wooden column.

[0010] Furthermore, the fire-resistant structure for a column-beam joint according to the present invention is a fire-resistant structure for a column-beam joint comprising, in the above-described invention, a fire-resistant wooden column comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, and a fire-resistant wooden beam comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, joined via a T-shaped connecting fitting comprising a gusset plate fixed to a plate that protrudes from the side end of the core material of the fire-resistant wooden beam toward the fire-resistant wooden column, and a base plate attached to the side surface of a concrete member fixed to the upper or lower surface of the core material of the fire-resistant wooden column, characterized in that a cement-based solidifying material is filled in the area around the connecting fitting between the side end of the fire-resistant wooden beam and the side surface of the concrete member.

[0011] Furthermore, the fire-resistant structure for the column-beam joint according to the present invention is characterized in that, in the invention described above, a fire-resistant covering material or a wood-based covering material is provided on the outside of the cement-based solidification material.

[0012] Furthermore, the fire-resistant structure for a column-beam joint according to the present invention is characterized in that, in the invention described above, a non-wood-based fire-resistant covering material is provided on the end face of the side end of the fire-resistant wooden beam. [Effects of the Invention]

[0013] The fire-resistant column-beam joint structure according to the present invention provides the effect of ensuring fire resistance equivalent to that of a single column and beam at the column-beam joint, as it includes a fire-resistant wooden column comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, and a fire-resistant wooden beam comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, via a T-shaped connecting fitting consisting of a gusset plate fixed to a plate that protrudes from the side end of the core material of the fire-resistant wooden beam toward the fire-resistant wooden column, and a base plate attached to the side surface of the core material of the fire-resistant wooden column. The structure further includes a cement-based solidifying material filled in the area around the connecting fitting between the side end of the fire-resistant wooden beam and the side surface of the fire-resistant wooden column.

[0014] Furthermore, according to the fire-resistant column-beam joint structure of the present invention, a fire-resistant wooden column comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, and a fire-resistant wooden beam comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material are joined via a T-shaped connecting fitting consisting of a gusset plate fixed to a plate that protrudes from the side end of the core material of the fire-resistant wooden beam toward the fire-resistant wooden column, and a base plate attached to the side surface of a concrete member fixed to the upper or lower surface of the core material of the fire-resistant wooden column. The fire-resistant column-beam joint structure comprises a cement-based solidifying material filled in the area around the connecting fitting between the side end of the fire-resistant wooden beam and the side surface of the concrete member, thereby achieving the effect of ensuring fire resistance performance equivalent to that of a single column and beam at the column-beam joint between the fire-resistant wooden column and the fire-resistant wooden beam.

[0015] Furthermore, according to the fire-resistant structure for column-beam joints of the present invention, a fire-resistant coating material or a wood-based coating material is provided on the outside of the cement-based solidification material, which has the effect of suppressing the temperature rise of the joint hardware and preventing carbonization of the core material.

[0016] Furthermore, according to the fire-resistant structure for column-beam joints of the present invention, a non-wood-based fire-resistant covering material is provided on the end face of the side end of the fire-resistant wooden beam. This suppresses the inflow of heat through gaps caused by the shrinkage of the cement-based solidification material, thereby contributing to preventing carbonization of the core material of the fire-resistant wooden beam. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 shows Embodiment 1 of the fire-resistant structure for a column-beam joint according to the present invention, where (1) is a vertical cross-sectional view and (2) is a horizontal cross-sectional view. [Figure 2] Figure 2 shows Embodiment 2 of the fire-resistant structure for a column-beam joint according to the present invention, where (1) is a vertical cross-sectional view and (2) is a horizontal cross-sectional view. [Figure 3]Figure 3 is a diagram relating to the fire resistance test of Example 1 of the present invention, wherein (1) shows the test specimen and temperature measurement positions, and (2) shows the internal temperature transition. [Figure 4] Figure 4 is a diagram relating to the fire resistance test of Example 2 of the present invention, wherein (1) shows the test specimen and temperature measurement positions, and (2) shows the internal temperature transition. [Figure 5] Figure 5 is a diagram relating to the fire resistance test of Example 3 of the present invention, wherein (1) shows the test specimen and temperature measurement positions, and (2) shows the internal temperature transition. [Figure 6] Figure 6 is a cross-sectional view showing the temperature measurement positions of the fire-resistant test specimens of Examples 1 to 3 of the present invention, wherein (1) is the measurement cross-section P1, (2) are the measurement cross-sections P2 and P3, (3) is the measurement cross-section P4, (4) are the measurement cross-sections P5 and P6, (5) is the measurement cross-section P7, and (6) is the measurement cross-section P8. MODE FOR CARRYING OUT THE INVENTION

[0018] The present invention has the features shown in the following (1) to (4). (1) Concrete is filled to suppress the temperature rise of the joint hardware. (2) The concrete-filled portion is covered with a reinforced gypsum board or a wooden board, which contributes to suppressing the temperature rise of the joint hardware and suppressing the temperature rise of the wooden core material of the fire-resistant wooden column. (3) By attaching a reinforced gypsum board of appropriate thickness to the end face of the fire-resistant wooden beam, the reinforced gypsum board absorbs heat to suppress the inflow of heat from the end face, thereby preventing carbonization of the wood that serves as the load-bearing member. (4) Joints are staggered so that no gap is generated at the junctions between materials around the beam-column joint.

[0019] In the present specification, after performing 1-hour heating or 2-hour heating in accordance with the standard heating curve specified in ISO834, stopping heating and allowing cooling for 24 hours, it is defined that 1-hour fire resistance or 2-hour fire resistance is achieved when the following two conditions are satisfied. (1) The fire stops spreading during cooling (self-extinguishes without fire extinguishing such as water spraying). (2) All of the wood of the core material remains uncarbonized after cooling. In the following, a fire resistance rating of 1 hour may be referred to as 1-hour fire resistance, and a fire resistance rating of 2 hours may be referred to as 2-hour fire resistance.

[0020] The following describes in detail an embodiment of the fire-resistant structure for a column-beam joint according to the present invention, based on the drawings. However, this embodiment does not limit the present invention.

[0021] <Embodiment 1> First, Embodiment 1 of the present invention will be described. Embodiment 1 is a structure designed for one hour of fire resistance. As shown in Figure 1, the fire-resistant structure 100 of the column-beam joint according to this embodiment 1 is a structure in which a fire-resistant wooden column 12 and a fire-resistant wooden beam 14 are joined via a connecting metal fitting 16, and includes concrete 18 (cement-based solidifying material) filled in the area around the connecting metal fitting 16.

[0022] (Fireproof wooden pillar) The fire-resistant wooden column 12 is a square-section column comprising a wooden core material 20 that supports the load, a fire-resistant covering material 22 provided around the entire outside of the core material 20, and a finishing material 24. The core material 20 can be made using laminated timber such as larch. The fire-resistant covering material 22 is made of two reinforced gypsum boards 22A provided on the outside of the core material 20 and a fire-resistant sheet 22B provided on the outside of those. The fire-resistant sheet 22B is a thermally expanding fire-resistant sheet that expands upon heating, and the combustion residue forms a fire-resistant insulation layer, exhibiting fire-resistant insulation performance. The finishing material 24 is made of a wooden board provided on the outside of the fire-resistant sheet 22B. In this embodiment 1, it is assumed that the side length of the cross-section of the core material 20 is 540 mm, the thickness of the reinforced gypsum board 22A is 15 mm, the thickness of the fire-resistant sheet 22B is 2 mm, and the thickness of the wooden board of the finishing material 24 is 15 mm, but the present invention is not limited to this.

[0023] (Fireproof wooden beam) The fire-resistant wooden beam 14 is a rectangular cross-section beam comprising a horizontally extending wooden core material 26, fire-resistant covering material 28 provided on the sides and bottom of the core material 26, and a finishing material 30. The core material 26 can be made using laminated timber such as larch. The fire-resistant covering material 28 consists of two reinforced gypsum boards 28A provided on the outside of the core material 26 and a fire-resistant sheet 28B provided on the outside of those. The fire-resistant sheet 28B is a thermally expanding fire-resistant sheet that expands upon heating, causing the combustion residue to form a fire-resistant insulation layer and exhibit fire-resistant insulation performance. The finishing material 30 consists of a wooden board provided on the outside of the fire-resistant sheet 28B. In this embodiment 1, the core material 26 is assumed to have a cross-sectional width of 250 mm and a height of 510 mm, the reinforced gypsum board 28A has a thickness of 15 mm, the fire-resistant sheet 28B has a thickness of 2 mm, and the wooden board of the finishing material 30 has a thickness of 15 mm. However, the present invention is not limited to this.

[0024] Reinforced gypsum board 32 (a non-wood-based fire-resistant covering material) is attached to the end faces 14A of the side ends of the fire-resistant wooden beam 14. This reinforced gypsum board 32 absorbs heat when heated by fire, suppressing the inflow of heat from the end faces 14A and preventing carbonization of the core material 26. It also suppresses the continued burning of the core material 26 due to heat inflow through gaps caused by the shrinkage of the concrete 18 after casting. The heat shielding performance and heat absorption effect improve as the thickness of the reinforced gypsum board 32 increases. For example, if the thickness of the reinforced gypsum board 32 is 21 mm or more, it is considered that fire resistance performance for one hour is guaranteed. In the example in Figure 1, two sheets of reinforced gypsum board 32 (thickness 21 mm) are attached to the end face 14A of the fire-resistant wooden beam 14 on the left, and one sheet of reinforced gypsum board 32 (thickness 21 mm) is attached to the end face 14A of the fire-resistant wooden beam 14 on the right. To prevent carbonization of the core material due to heat inflow from the joints of the reinforced gypsum board 32, the reinforced gypsum board 32 is attached so that the joints are stepped. The fire-resistant covering material provided on the end face 14A of the side end of the fire-resistant wooden beam 14 is not limited to reinforced gypsum board 32, but any non-wood-based fire-resistant covering material may be used. Furthermore, the thickness and number of sheets of this fire-resistant covering material can be appropriately set according to the required fire resistance performance.

[0025] A slit-shaped groove 34 extending in the direction of the beam axis is formed in the central part of the side end face of the core material 26 and the reinforced gypsum board 32. A part of a steel plate 36 is inserted into the groove 34, and the plate 36 and the core material 26 are fixed together by drift pins 40 inserted through multiple through holes 38 that penetrate each other in the front-to-back direction. To prevent opening, a through bolt 41 is inserted in only one place in the central part. The end 41A of the through bolt 41 is housed in a recess 42 formed on the side surface of the core material 26 and passes through a fixing plate 44 that is positioned in contact with the side surface of the recess 42. This end 41A is threaded, and a nut 46 is screwed onto the outside of the fixing plate 44. The end 41A is fixed to the side surface of the recess 42 via the fixing plate 44 by fastening the nut 46.

[0026] A flooring material 48 is provided on the upper surface of the core material 26. The flooring material 48 is made of, for example, a floor slab using reinforced concrete or ALC (autoclaved lightweight concrete) panels. In the example shown in the figure, the fire-resistant wooden beams 14 are shown only on the left and right sides of the fire-resistant wooden column 12, but similar fire-resistant wooden beams 14 may also be placed on either the left or right side or the front and rear surfaces of the fire-resistant wooden column 12 to form column-beam joints in each section.

[0027] (Connecting hardware) The connecting hardware 16 has a T-shaped cross-section in a horizontal view and consists of a gusset plate 50 that is bolted to a plate 36 at the side end of the fire-resistant wooden beam 14, and a base plate 52 that is connected to the side end of the gusset plate 50 and attached to the side surface of the core material 20 of the fire-resistant wooden column 12. In this embodiment 1, assuming a 1-hour fire resistance specification, the base plate 52 is directly attached to the core material 20 in order to make the fire-resistant wooden column 12 a continuous column. The fire-resistant covering material 22 of the fire-resistant wooden column 12 is placed up to near the periphery of the base plate 52.

[0028] The gusset plate 50 is butted in the left-right direction against a plate 36 that protrudes from the side end of the core material 26 of the fire-resistant wooden beam 14 toward the fire-resistant wooden column 12, and a plate 54 is positioned on the front and rear surfaces of this butt joint, straddling the gusset plate 50 and plate 36. Each plate 50, 36, and 54 is joined together by multiple bolts 58 passed through through holes 56.

[0029] The base plate 52 is fixed to the fire-resistant wooden column 12 via steel rods 60 that are arranged to penetrate the column horizontally in the left-right direction. The steel rods 60 are arranged at two locations spaced apart in the vertical direction and at two locations on either side of the connection between the gusset plate 50 and the base plate 52, but the present invention is not limited to this, and other arrangement layouts and quantities are also possible.

[0030] The left and right ends 60A of the steel rod 60 pass through through holes 52A provided in the base plate 52. These ends 60A are threaded, and nuts 62 are screwed onto the outside of the base plate 52. The ends 60A are fixed to the base plate 52 by fastening the nuts 62.

[0031] The steel bar 60 may be any of the following: a fully threaded bolt, a round steel bar with threads cut to both ends, an anchor bolt used in the foundation of a building, or a deformed reinforcing bar with threads cut to both ends.

[0032] (concrete) The concrete 18 is intended to suppress the temperature rise of the connecting hardware 16 and is filled in the area around the connecting hardware 16 between the side end of the fire-resistant wooden beam 14 and the side surface of the fire-resistant wooden column 12. The heat capacity increases as the thickness of the concrete 18 increases, and the heat shielding performance improves. For this reason, if the thickness of the concrete 18 is greater than or equal to that of the test specimen described later, it is considered that the predetermined fire resistance performance (for example, 1 hour) can be guaranteed. It is desirable to pour the concrete 18 at the same time as pouring the concrete for the floor material 48, taking workability into consideration. Furthermore, the present invention is not limited to concrete 18, and other cement-based solidifying materials such as mortar may be used instead of concrete 18.

[0033] Fire-resistant covering material 64 and finishing material 66 are provided on the sides and bottom of the concrete 18. Flooring material 48 is provided on the top of the concrete 18. The fire-resistant covering material 64 is made of reinforced gypsum board. The finishing material 66 is made of a wooden board provided on the outside of the fire-resistant covering material 64. Covering the filling portion of the concrete 18 with reinforced gypsum board and wooden board helps to suppress the temperature rise of the connecting hardware 16 and prevent carbonization of the core material 20 of the fire-resistant wooden column 12. In this embodiment 1, it is assumed that the reinforced gypsum board of the fire-resistant covering material 64 has a thickness of 12.5 mm and the wooden board of the finishing material 66 has a thickness of 10 mm, but it is not limited to this. The heat-shielding performance improves as the thickness of the wooden board increases, so it is thought that the required fire resistance performance can be guaranteed if the thickness of the wooden board is 10 mm or more.

[0034] The reinforced gypsum board fire-resistant coating material 64 is attached to the surface of the concrete 18 after the concrete 18 has been poured and cured. A gypsum-based adhesive can be used for attachment. However, for the bottom surface, it is desirable to use concrete screws and adhesive together to prevent detachment. For attaching the wooden boards of the finishing material 66, a vinyl acetate resin adhesive and staples can be used. Alternatively, the reinforced gypsum board may be omitted, and a configuration in which wooden boards are attached to wooden furring strips may be adopted. It is desirable to use concrete screws for attaching the wooden furring strips. Even in a specification without reinforced gypsum board, the required fire resistance performance can be ensured as shown in the fire resistance test described later.

[0035] According to this embodiment 1, the column-beam joint (concrete-filled section) can be made to have fire resistance performance equivalent to that of the fire-resistant wooden column 12 and the fire-resistant wooden beam 14. This ensures the fire safety of buildings using the fire-resistant wooden column 12 and the fire-resistant wooden beam 14. Furthermore, the concrete 18 of the column-beam joint can be constructed simultaneously with the concrete pouring of the flooring material 48 to be built on top of the fire-resistant wooden beam 14. This reduces the labor and cost of concrete pouring. Therefore, it also offers excellent workability. In addition, by installing the reinforced gypsum board 32 on the end faces 14A of the fire-resistant wooden beam 14 in the factory, the construction period at the construction site can be shortened.

[0036] <Embodiment 2> Next, Embodiment 2 of the present invention will be described. Embodiment 2 is a structure designed for 2-hour fire resistance. As shown in Figure 2, the fire-resistant structure 200 of the column-beam joint according to this embodiment 2 is a structure in which a fire-resistant wooden column 12 and a fire-resistant wooden beam 14 are joined via connecting hardware 16 on the side of a concrete member 68 fixed to the upper surface of the fire-resistant wooden column 12, and includes concrete 18 (cement-based solidifying material) filled in the area around the connecting hardware 16.

[0037] (Fireproof wooden pillar) The fire-resistant wooden column 12 is the same as in Embodiment 1 described above. In this Embodiment 2, it is assumed that the cross-section of the core material 20 has a side length of 540 mm, the reinforced gypsum board 22A has a thickness of 25 mm, the fire-resistant sheet 22B has a thickness of 2 mm, and the wooden board of the finishing material 24 has a thickness of 15 mm, but the fire-resistant wooden column of the present invention is not limited to these. Furthermore, the fire-resistant coating material of the present invention is not limited to these, and fire-resistant coating materials of other materials may be used.

[0038] (Fireproof wooden beam) The fire-resistant wooden beam 14 is the same as in Embodiment 1 described above. In this Embodiment 2, the cross-sectional width of the core material 26 is assumed to be 250 mm, the height 510 mm, the thickness of the reinforced gypsum board 28A is 25 mm, the thickness of the fire-resistant sheet 28B is 2 mm, and the thickness of the wooden board of the finishing material 30 is 15 mm, but the fire-resistant wooden beam of the present invention is not limited to this. Furthermore, the fire-resistant coating material of the present invention is not limited to this, and fire-resistant coating materials of other materials may be used.

[0039] Similar to Embodiment 1 described above, reinforced gypsum board 32 (a non-wood-based fire-resistant covering material) is attached to the end faces 14A of the side ends of the fire-resistant wooden beam 14. For example, if the thickness of the reinforced gypsum board 32 is 50 mm or more, it is considered that a 2-hour fire resistance performance can be guaranteed. In the example shown in Figure 2, three sheets of reinforced gypsum board 32 (21 mm thick) are attached to the end face 14A of the left fire-resistant wooden beam 14, and two sheets of reinforced gypsum board 32 (25 mm thick) are attached to the end face 14A of the right fire-resistant wooden beam 14.

[0040] Similar to Embodiment 1 described above, the plate 36 and the core material 26 are fixed with drift pins 40. A floor material 48 is provided on the upper surface of the core material 26. The floor material 48 is connected to the side surface of the concrete member 68. In the example shown in the figure, the fire-resistant wooden beam 14 is shown to be placed only on the left and right sides of the concrete member 68, but similar fire-resistant wooden beams 14 may be placed on either the left or right side, or on the front and rear surfaces of the concrete member 68, to form column-beam joints in each area.

[0041] (Concrete members) The concrete member 68 is a square-section precast concrete fixed to the upper surface of the core material 20 at the top of the fire-resistant wooden column 12. In this embodiment 2, the concrete member 68 is assumed to have a horizontal cross-section with sides of 530 mm and a height of 850 mm, but the present invention is not limited to this. Eight vertically extending recessed holes 68A are provided on the lower surface of the concrete member 68 at approximately equal intervals in the circumferential direction of a circle centered on the axis of the concrete member 68. The upper portion of a lag screw 70, which is driven into the core material 20 from the upper surface of the core material 20 of the fire-resistant wooden column 12, is fitted into these recessed holes 68A. Grout material 72 is filled into the gap between the lag screw 70 and the recessed holes 68A, thereby integrating the concrete member 68 and the core material 20. Furthermore, in order to suppress heat conduction from the concrete member 68 to the core material 20, the fire-resistant covering material 22 and finishing material 24 of the fire-resistant wooden column 12 are extended upwards to the lower part of the concrete member 68, covering the outer perimeter of this portion of the concrete member 68. Finishing material 76 is provided around the front and rear outer perimeters of the upper concrete member 68 via multiple wooden furring strips 74. The finishing material 76 is made of the same material and thickness as the finishing material 24 of the fire-resistant wooden column 12. It is considered advantageous in terms of fire resistance if the upward length of the fire-resistant covering material 22 is greater than, for example, 133 mm.

[0042] (Connecting hardware) The connecting hardware 16 has a T-shaped cross-section in a horizontal view and consists of a gusset plate 50 that is bolted to the plate 36 at the side end of the fire-resistant wooden beam 14, and a base plate 52 that is connected to the side end of the gusset plate 50 and attached to the side surface of the concrete member 68. The gusset plate 50 and the plate 36 are fixed in the same manner as in Embodiment 1 described above.

[0043] The base plate 52 is fixed to the concrete member 68 via a steel rod 60 that is positioned to penetrate the concrete member 68 horizontally in the left-right direction. The left and right ends 60A of the steel rod 60 pass through through holes 52A provided in the base plate 52. These ends 60A are threaded, and nuts 62 are screwed onto the outside of the base plate 52. The ends 60A are fixed to the base plate 52 by tightening the nuts 62.

[0044] The steel bar 60 may be any of the following: a fully threaded bolt, a round steel bar with threads cut to both ends, an anchor bolt used in the foundation of a building, or a deformed reinforcing bar with threads cut to both ends.

[0045] (concrete) The concrete 18 is intended to suppress the temperature rise of the connecting hardware 16 and is filled in the area around the connecting hardware 16 between the side end of the fire-resistant wooden beam 14 and the side surface of the concrete member 68. The greater the thickness of the concrete 18, the greater the heat capacity and the better the heat shielding performance. For this reason, if the thickness of the concrete 18 is greater than or equal to that of the test specimen described later, it is considered that the predetermined fire resistance performance (for example, 2 hours) can be guaranteed. It is desirable to pour the concrete 18 at the same time as pouring the concrete for the floor material 48, taking workability into consideration. Furthermore, the present invention is not limited to concrete 18, and other cement-based solidifying materials such as mortar may be used instead of concrete 18.

[0046] Similar to Embodiment 1 above, fire-resistant covering material 64 and finishing material 66 are provided on the sides and bottom of the concrete 18. Flooring material 48 is provided on the top surface of the concrete 18. The fire-resistant covering material 64 is made of reinforced gypsum board. The finishing material 66 is made of a wooden board provided on the outside of the fire-resistant covering material 64. Covering the filling portion of the concrete 18 with reinforced gypsum board and wooden board helps to suppress the temperature rise of the connecting hardware 16 and prevent carbonization of the core material 20 of the fire-resistant wooden column 12. In this Embodiment 2, it is assumed that the reinforced gypsum board of the fire-resistant covering material 64 has a thickness of 12.5 mm and the wooden board of the finishing material 66 has a thickness of 10 mm, but it is not limited to these. As the thickness of the wooden board increases, the heat shielding performance improves, so it is thought that the required fire resistance performance can be ensured if the thickness of the wooden board is 10 mm or more.

[0047] The reinforced gypsum board fire-resistant coating material 64 is attached to the surface of the concrete 18 after the concrete 18 has been poured and cured. A gypsum-based adhesive can be used for attachment. However, for the bottom surface, it is desirable to use concrete screws and adhesive together to prevent detachment. For attaching the wooden boards of the finishing material 66, a vinyl acetate resin adhesive and staples can be used. Alternatively, the reinforced gypsum board may be omitted, and a configuration in which wooden boards are attached to wooden furring strips may be adopted. It is desirable to use concrete screws for attaching the wooden furring strips. Even in a specification without reinforced gypsum board, the required fire resistance performance can be ensured as shown in the fire resistance test described later.

[0048] According to this second embodiment, the column-beam joint (concrete-filled section) can be made to have fire resistance performance equivalent to that of the fire-resistant wooden column 12 and the fire-resistant wooden beam 14. This ensures the fire safety of buildings using the fire-resistant wooden column 12 and the fire-resistant wooden beam 14. Furthermore, the concrete 18 of the column-beam joint can be constructed simultaneously with the concrete pouring of the floor material 48 to be built on top of the fire-resistant wooden beam 14. This reduces the labor and cost of concrete pouring. The fire-resistant wooden column 12 and the concrete member 68 are directly joined by lag screws 70 and grout material 72, improving constructability. Therefore, it also has excellent constructability. In addition, the reinforced gypsum board 32 on the end face 14A of the fire-resistant wooden beam 14 is installed in the factory, which shortens the construction period at the construction site.

[0049] <Verification of the effects of the present invention> Next, we will describe the tests and results conducted to verify the effects of the present invention.

[0050] Test specimens simulating the fire-resistant structure of the present invention were prepared, and fire resistance tests were conducted to investigate their fire resistance performance. The fire resistance tests were carried out by placing the test specimens in a furnace and heating them for 1 or 2 hours according to the standard heating curve specified in ISO 834, followed by 24 hours of cooling in the furnace. Three specifications of test specimens (test specimens 1 to 3) were prepared. Test specimen 1 has the structure shown in Embodiment 1 above, and is a 1-hour fire-resistant specification (Example 1) in which the concrete filling section is covered with reinforced gypsum board (thickness 12.5 mm) and wooden board (thickness 10 mm). Test specimen 2 has the structure shown in Embodiment 2 above, and is a 2-hour fire-resistant specification (Example 2) in which the concrete filling section is covered with reinforced gypsum board (thickness 12.5 mm) and wooden board (thickness 10 mm). Test specimen 3 is a 2-hour fire-resistant specification (Example 3) in which the reinforced gypsum board is omitted in Embodiment 2 above, and the concrete filling section is covered with a wooden board (thickness 10 mm). Wooden boards (10mm thick) are attached to wooden furring strips (20mm thick).

[0051] The specifications common to test specimens 1 to 3 are as follows: First, the core material 26 of the fire-resistant wooden beam 14 was made of laminated larch timber (symmetrical different grades E105-F315, width 250 x height 510 mm). The core material 20 of the fire-resistant wooden column 12 was made of laminated larch timber (same grade E95-F315, 540 x 540 mm). The steel rod 60 was fitted with M30 through bolts (with φ32 pre-drilled holes). The base plate 52 was made of a plate with a thickness of 25 x width 200 x height 400 mm. The gusset plate 50 was made of a plate with a thickness of 12 x height 360 x length 165 mm. The plate 36 was made of a plate with a thickness of 12 x height 360 mm. The surface of the concrete 18 was finished so that the sides and bottom surfaces were vertical and horizontal planes, respectively. The top surface of the concrete 18 was finished flush with the top surface of the core material 26. Precast concrete (530 x 530 mm, 850 mm high) was used for the concrete members 68 of test specimens 2 and 3. To suppress heat conduction from the concrete members 68 to the core material 20 of the fire-resistant wooden column 12, the fire-resistant covering material 22 of the fire-resistant wooden column 12 was raised 133 mm towards the concrete member 68. The lag screws 70 were 760 mm long and φ25 mm in diameter, and were inserted into the recessed holes 68A (φ50 mm) of the concrete member 68, with grout material 72 filling the gaps. The diameter of the drift pins 40 of the fire-resistant wooden beam 14 was 22 mm.

[0052] The thickness of the concrete 18 for test specimens 1 to 3 was set as follows: First, for test specimen 1, the thickness was 97 mm when measured downward from the lower end of the gusset plate 50 of the connecting hardware 16, 42 mm when measured laterally from the side end of the base plate 52, and 77 mm when measured downward from the lower end. For test specimens 2 and 3, the thickness was 117 mm when measured downward from the lower end of the gusset plate 50 of the connecting hardware 16, 62 mm when measured laterally from the side end of the base plate 52, and 97 mm when measured downward from the lower end.

[0053] The fire-resistant covering material 28 and finishing material 30 for the fire-resistant wooden beams 14 of test specimens 1 to 3 were set as follows. First, for the fire-resistant covering material 28 on the sides and bottom of the fire-resistant wooden beam 14 of test specimen 1, two sheets of reinforced gypsum board (15 mm thick x 2) and a fire-resistant sheet (2 mm thick) were used. For the finishing material 30, a wooden board (cedar veneer, 15 mm thick) was used. For the reinforced gypsum board 32 attached to the end face 14A of the fire-resistant wooden beam 14, two sheets of reinforced gypsum board (21 mm thick x 2) were used for the fire-resistant wooden beam 14 on the left side of Figure 3, and one sheet of reinforced gypsum board (21 mm thick) was used for the fire-resistant wooden beam 14 on the right side of Figure 3. In addition, for the fire-resistant covering material 28 on the sides and bottom of the fire-resistant wooden beams 14 of test specimens 2 and 3, two sheets of reinforced gypsum board (25 mm thick x 2) and a fire-resistant sheet (2 mm thick) were used. For the finishing material 30, a wooden board (cedar veneer, 15 mm thick) was used. For the reinforced gypsum board 32 attached to the end face 14A of the fire-resistant wooden beam 14, three reinforced gypsum boards (21 mm thick x 3) were used for the fire-resistant wooden beam 14 on the left side of Figures 4 and 5, and two reinforced gypsum boards (25 mm thick x 2) were used for the fire-resistant wooden beam 14 on the right side of Figures 4 and 5.

[0054] Figures 3 to 5 show schematic diagrams of the test specimens, temperature measurement locations, and temperature measurement results. Figure 3 corresponds to test specimen 1, Figure 4 to test specimen 2, and Figure 5 to test specimen 3. The temperature measurement locations for temperature measurement cross-sections P1 to P8 are as shown in Figure 6. Figures 3(1), 4(1), and 5(1) show the highest temperatures at each cross-section. The temperature measurement results in Figures 3(2), 4(2), and 5(2) use the highest temperature value among the temperatures measured at each measurement location in temperature measurement cross-sections P1 to P8.

[0055] As shown in Figures 3 and 4, the maximum temperature of the wooden core material around the joints in both test specimens 1 and 2 was 200°C or less. Furthermore, the maximum temperature of the connecting hardware was 80°C or less for test specimen 1 (1-hour fire resistance specification) and 120°C or less for test specimen 2 (2-hour fire resistance specification), neither of which reached the temperature at which the wooden core material would carbonize. In addition, no discoloration or carbonization was observed on the surface of the wooden core material around the joints.

[0056] On the other hand, as shown in Figure 5, for test specimen 3 (2-hour fire-resistant specification), the maximum temperature of the wooden core material around the joint was 200°C or less. Furthermore, the maximum temperature of the connecting hardware was 150°C or less, which did not reach the temperature at which the wooden core material would carbonize. In addition, no discoloration or carbonization was observed on the surface of the wooden core material around the joint. Therefore, it was confirmed that the fire-resistant covering structure around the column-beam joint in this embodiment has fire resistance for one or two hours.

[0057] As described above, the fire-resistant structure for a column-beam joint according to the present invention is a fire-resistant wooden column comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, and a fire-resistant wooden beam comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, joined via a T-shaped connecting fitting consisting of a gusset plate fixed to a plate that protrudes from the side end of the core material of the fire-resistant wooden beam toward the fire-resistant wooden column, and a base plate attached to the side surface of the core material of the fire-resistant wooden column. The fire-resistant structure for a column-beam joint comprises a cement-based solidifying material filled in the area around the connecting fitting between the side end of the fire-resistant wooden beam and the side surface of the fire-resistant wooden column, so that fire resistance performance equivalent to that of a column and beam alone can be ensured at the column-beam joint of the fire-resistant wooden column and the fire-resistant wooden beam.

[0058] Furthermore, according to the fire-resistant column-beam joint structure of the present invention, a fire-resistant wooden column comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, and a fire-resistant wooden beam comprising a wooden core material that supports a load and a fire-resistant covering material provided on the outside of the core material, are joined via a T-shaped connecting fitting consisting of a gusset plate fixed to a plate that protrudes from the side end of the core material of the fire-resistant wooden beam toward the fire-resistant wooden column, and a base plate attached to the side surface of a concrete member fixed to the upper or lower surface of the core material of the fire-resistant wooden column, wherein a cement-based solidifying material is filled in the area around the connecting fitting between the side end of the fire-resistant wooden beam and the side surface of the concrete member, so that fire resistance performance equivalent to that of a column and beam alone can be ensured at the column-beam joint of the fire-resistant wooden column and the fire-resistant wooden beam.

[0059] Furthermore, according to the fire-resistant structure for column-beam joints of the present invention, a fire-resistant coating material or a wood-based coating material is provided on the outside of the cement-based solidification material, which can help suppress the temperature rise of the joint hardware and prevent carbonization of the core material.

[0060] Furthermore, according to the fire-resistant structure for column-beam joints of the present invention, a non-wood-based fire-resistant covering material is provided on the end face of the side end of the fire-resistant wooden beam. This suppresses the inflow of heat through gaps caused by the shrinkage of the cement-based solidification material and contributes to preventing carbonization of the core material of the fire-resistant wooden beam. [Industrial applicability]

[0061] As described above, the fire-resistant structure for column-beam joints according to the present invention is useful for joints between fire-resistant wooden columns and fire-resistant wooden beams, and is particularly suitable for ensuring fire resistance equivalent to that of columns and beams. [Explanation of symbols]

[0062] 12 Fireproof wooden pillar 14 Fireproof wooden beams 14A Small end 16. Connecting hardware 18. Concrete (cement-based solidifying agent) 20, 26 Core material 22,28,64 Fireproof cladding 22A Reinforced Gypsum Board 22B Fireproof Sheet 24, 30, 66, 76 Finishing materials 32. Reinforced gypsum board (non-wood-based fire-resistant coating material) 34 Concave groove part 36,54 Plate 38 Through holes 40 drift pins 41 Through bolts 41A, 60A end 42 recess 44 Fixing plate 46,62 nuts 48 Flooring 50 Gusset Plates 52 Base Plate 52A Through hole 56 Through hole 58 volts 60 steel bar 68 Concrete members 68A recessed hole 70 lag screws 72 Grout material 74 Wooden rafters 100,200 Fire-resistant structure of column-beam joints

Claims

1. A fire-resistant column-beam joint structure comprising a fire-resistant wooden column comprising a wooden core material that supports a load, a fire-resistant covering material provided on the outside of the core material, and a finishing material provided on the outside of the fire-resistant covering material, and a fire-resistant wooden beam comprising a wooden core material that supports a load, and a fire-resistant covering material provided on the outside of the core material, is joined via a T-shaped connecting fitting consisting of a gusset plate fixed to a plate that protrudes from the side end of the core material of the fire-resistant wooden beam toward the fire-resistant wooden column, and a base plate attached to the side surface of a concrete member fixed to the upper surface of the core material of the fire-resistant wooden column, wherein A cement-based solidifying material is filled in the area surrounding the connecting hardware between the side end of the fire-resistant wooden beam and the side surface of the concrete member, A lag screw is fitted into a recessed hole provided on the lower surface of the concrete member and driven into the interior from the upper surface of the core material of the fire-resistant wooden column, The lag screw and the grout material filled in the gap between the recessed hole are provided. The lag screw and the grout material integrate the concrete member and the core material of the fire-resistant wooden column. The fire-resistant covering material and finishing material of the fire-resistant wooden column are extended to the lower portion of the concrete member, covering the outside of the lower portion of the concrete member, and the finishing material is provided on the outside of the upper portion of the concrete member via a plurality of wooden furring strips, characterized in that the finishing material is provided on the outside of the upper portion of the lower portion of the concrete member.

2. The gusset plate is abutted against the plate in the left-right direction, a connecting plate is positioned on the front and rear surfaces of the abutting portion so as to straddle the gusset plate and the plate, the gusset plate and the connecting plate are joined by bolts passed through through holes, and the plate and the connecting plate are joined by bolts passed through through holes, characterized in that the column-beam joint structure is as described in claim 1.

3. The fire-resistant structure for a column-beam joint according to claim 1 or 2, characterized in that a fire-resistant covering material made of reinforced gypsum board with a thickness of 12.5 mm or more is provided on the outside of the cement-based solidification material.

4. The fire-resistant structure for a column-beam joint according to claim 3, characterized in that a fire-resistant covering material made of reinforced gypsum board with a thickness of 21 mm or more is provided on the end face of the side end of the fire-resistant wooden beam.

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