Fire-resistant structure of column-beam connection

Abstract

To provide a fire-resistant structure constituted of column-beam connection parts which can secure fire resistance efficiency equivalent to that of the column / beam itself.SOLUTION: A fire-resistant structure 10 is constituted of a column-beam connection part that is constructed by connecting: a fire-resistant ligneous column 12, which consists of a load-supporting ligneous core material 20 and a first fire-resistant covering material 22 arranged outside of the core material 20; and a fire-resistant steel frame beam 14, which consists of a steel frame member 28 and a dry-type second fire-resistant covering material 30 arranged outside of the steel frame member 28; via a joint metal 16 with a T-shape section, which consists of a gusset plate 40 attached to the side end part of the steel frame member 28 and a base plate 42 attached to the first fire-resistant covering material 22 at the side surface of the fire-resistant ligneous column 12. The fire-resistant structure's fittings include a dry-type third fire-resistant covering material 18 arranged on the surface of the base plate 42 and the gusset plate 40, fire resistance efficiency of the third fire-resistant covering material 18 being designed to be greater than that of the second fire-resistant covering material 30.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Previously, the applicant of this patent has developed a fire-resistant wooden component (Slim Fire Wood (registered trademark)) that ensures fire resistance for one or two hours by fire-proofing wood that supports a load with reinforced gypsum board and a fire-resistant sheet (see, for example, Patent Document 1). Fire-resistant wooden components are required to ensure that the wood, which is the load-supporting part, does not carbonize during and after the fire heating, and fire resistance is ensured by covering it with a fire-resistant coating material according to the required fire resistance time so that the temperature is below the carbonization temperature of wood, about 200 to 260°C.

[0003] On the other hand, steel components are said to collapse when the temperature of the steel reaches about 550°C, so by covering them with fire-resistant coating materials such as sprayed rock wool, wrapped rock wool, calcium silicate boards, and fire-resistant paint, the rise in steel temperature can be suppressed and fire resistance can be ensured.

[0004] Furthermore, as conventional fireproof structures for column-beam joints, those described in Patent Documents 2 to 4 are known, for example. In Patent Document 2, at the joint between a fireproof wooden column and a steel beam, the steel beam is covered to prevent the core material of the fireproof wooden column from burning. In Patent Document 3, at the joint between a wooden column and a steel beam, high-density wood or wood that has been treated with a flame retardant is covered as a burning substitute. In Patent Document 4, at the joint between a fireproof wooden column and a steel beam, the web part of the steel beam near the column is filled with concrete to increase the heat capacity, and the general part of the steel beam is covered with a fireproof coating material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6414670 [Patent Document 2] Patent No. 5990425 [Patent Document 3] Patent No. 6936561 [Patent Document 4] JP 2023-9421 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in a structure in which connecting metal fittings such as base plates or gusset plates are directly attached to the fire-resistant wooden columns and steel beams are joined via the connecting metal fittings, it may not be possible to ensure the fire resistance of the fire-resistant wooden columns.

[0007] As mentioned above, because the allowable temperatures for fire heating of wood and steel members are different, even if the steel members are below the collapse temperature of 550°C, the heat transfer from the fire-resistant covered steel beams and metal joints to the wood core of the fire-resistant wood column may cause the wood core to reach a temperature of 200-260°C, carbonize, and lose its strength. For this reason, a structure with improved fire resistance around the joints was required so as not to impair the fire resistance of the fire-resistant wood column. In addition, a fire-resistant structure for column-beam joints using a dry method with excellent workability was required to reduce the labor and cost of construction.

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

[0009] In order to solve the above-mentioned problems and achieve the object, the fireproof structure of a column-beam joint of the present invention is a fireproof wooden column comprising a wooden core material for supporting a load and a first fireproof covering material provided on the outside of the core material, and a fireproof steel beam comprising a steel member and a dry-type second fireproof covering material provided on the outside of the steel member, joined together via a T-shaped cross-section connecting metal fitting consisting of a gusset plate fixed to the side end of the steel member and a base plate attached to the first fireproof covering material on the side of the fireproof wooden column, characterized in that the fireproof structure comprises a dry-type third fireproof covering material provided on the surfaces of the base plate and the gusset plate, and the fireproof performance of the third fireproof covering material is higher than that of the second fireproof covering material.

[0010] In addition, another fire-resistant structure of a column-beam joint according to the present invention is characterized in that, in the above-mentioned invention, the thickness of the third fire-resistant covering material is greater than the thickness of the second fire-resistant covering material.

[0011] In addition, another fire-resistant structure of a column-beam joint according to the present invention is characterized in that, in the above-mentioned invention, the second fire-resistant covering material and the third fire-resistant covering material are wrapped-around rock wool. Effect of the Invention

[0012] According to the fireproof structure for a column-beam joint of the present invention, a fireproof wood column including a wood core material that supports a load and a first fireproof covering material provided on the outside of the core material, and a fireproof steel beam including a steel member and a dry second fireproof covering material provided on the outside of the steel member are joined together via a T-shaped metal joint consisting of a gusset plate fixed to the side end of the steel member and a base plate attached to the first fireproof covering material on the side of the fireproof wood column, and a dry third fireproof covering material provided on the surfaces of the base plate and the gusset plate, and the fireproof performance of the third fireproof covering material is higher than that of the second fireproof covering material, so that the fireproof structure for a column-beam joint between a fireproof wood column and a fireproof steel beam can ensure fireproof performance equivalent to that of the column-beam alone. In addition, dry fire-resistant coating materials reduce the effort required for curing compared to wet fire-resistant coating materials, and since they do not require drying time, they lead to shorter construction times.

[0013] In addition, according to another fire-resistant structure of a column-beam joint of the present invention, the thickness of the third fire-resistant covering material is greater than the thickness of the second fire-resistant covering material, so that it is possible to ensure fire resistance performance at a column-beam joint between a fire-resistant wood column and a fire-resistant steel beam equivalent to that of the column and beam alone.

[0014] In addition, according to another fire-resistant structure of a column-beam joint of the present invention, the second fire-resistant covering material and the third fire-resistant covering material are wrapped rock wool, which has the effect of making them easy to install. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a vertical sectional view showing an embodiment of a fireproof structure for a beam-column joint according to the present invention. [Diagram 2] FIG. 2 is a schematic diagram of the test specimen 1 used in the fire resistance test, where (1) is a vertical cross-sectional view and (2) is a horizontal cross-sectional view. [Diagram 3] FIG. 3 is a schematic diagram of the test specimen 2 used in the fire resistance test, where (1) is a vertical cross-sectional view and (2) is a horizontal cross-sectional view. [Figure 4] FIG. 4 shows the fire resistance test results of test specimen 1, where (1) is a temperature measurement position diagram, (2) is an internal temperature transition diagram of Example 1-1, and (3) is an internal temperature transition diagram of Example 1-2. [Diagram 5] FIG. 5 shows the fire resistance test results of test specimen 2, where (1) is a temperature measurement position diagram, (2) is an internal temperature transition diagram of Example 2-1, and (3) is an internal temperature transition diagram of Example 2-2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a fire-resistant structure for a column-beam joint according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these preferred embodiments.

[0017] In this specification, it is defined that a 1-hour or 2-hour fire resistance performance has been achieved when the following two conditions are met after heating for 1 hour or 2 hours in accordance with the standard heating curve specified in ISO834, stopping the heating, and allowing to cool for 24 hours: (1) The fire should stop burning while it is cooling (it should go out on its own without the need for water or other extinguishing measures). (2) After cooling, all of the wood in the pillar core remains uncarbonized.

[0018] As shown in Fig. 1, a fire-resistant structure 10 for a column-beam joint according to an embodiment of the present invention is a structure in which a fire-resistant wooden column 12 and a fire-resistant steel beam 14 are joined via a joint metal 16, and a dry fire-resistant covering material 18 is provided around the joint metal 16. This embodiment is intended for a structure that ensures fire resistance of 1 hour or 2 hours.

[0019] (Fireproof wooden pillar) The fireproof wooden column 12 is a column with a rectangular cross section, which includes a wooden core material 20 that supports a load, a fireproof covering material 22 provided on the entire outer circumference of the core material 20, and a finishing material 24. The core material 20 can be made of laminated wood such as larch. The fireproof covering material 22 is the first fireproof covering material of the present invention, and is composed of two reinforced gypsum boards 22A provided on the outer side of the core material 20 and a fireproof sheet 22B provided on the outer side. The fireproof sheet 22B is a thermally expandable fireproof sheet that expands when heated to form a heat insulating layer and exhibits heat insulating performance. The finishing material 24 is composed of a wooden board provided on the outer side of the fireproof sheet 22B. In this embodiment, it is assumed that one side of the cross section of the core material 20 is several hundred mm, the thickness of the fireproof covering material 22 is about 30 to 50 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.

[0020] (Fire-resistant steel beams) The fire-resistant steel beam 14 is composed of a steel beam 28 made of H-shaped steel extending horizontally, and fire-resistant covering material 30 provided on both the left and right outer sides and the underside of the steel beam 28. A floor material 32 is provided on the upper surfaces of the steel beam 28 and the fire-resistant wooden columns 12. The floor material 32 is composed of a floor slab using, for example, reinforced concrete or ALC (lightweight aerated concrete) boards. The steel beam 28 is composed of H-shaped steel (steel member) having an upper flange 34, a lower flange 36, and a web 38. The steel beam in this embodiment is H-346×174×6×9 mm (section shape coefficient: 235.7 m -1 ) is used. The fireproof coating material 30 is a second dry fireproof coating material of the present invention, and is made of a blanket of wrapped rock wool. For example, high heat resistant rock wool (product name: Makibee (registered trademark)) manufactured by Nichias Corporation can be used as the wrapped rock wool. In the example shown in the figure, the fireproof steel beam 14 is arranged only on the right side of the fireproof wooden column 12, but a similar fireproof steel beam 14 may be arranged on the right side, front and rear sides, etc. of the fireproof wooden column 12 to form a column-beam joint at each location.

[0021] The fire-resistant covering material 30 is arranged so as to be wrapped around the steel beam 28 in a U-shape when viewed in the beam axis direction. Specifically, it is arranged so as to continuously cover the underside of the floor material 32 above the upper flange 34 of the steel beam 28, the end surface of the upper flange 34, and the end surface and underside of the lower flange 36. The fire-resistant covering material 30 is fixed to the steel beam 28 by fastening the ends to the upper flange 34 with welding pins (not shown).

[0022] The thickness of the wrapped rock wool used in the fire-resistant coating material 30 is preferably 65 mm or more, which corresponds to a 2-hour fire resistance, for a 1-hour fire resistance, and 105 mm or more, which corresponds to a 3-hour fire resistance, for a 2-hour fire resistance. -1 The specified fire resistance is guaranteed if the steel dimensions are as follows. The wrapped rock wool can be configured in one layer or two or more layers. For example, if the wrapping rock wool covering the steel beam 28 is to be 105 mm thick, wrapping rock wool (65 mm thick) is attached to the steel beam 28, and then wrapping rock wool (40 mm thick) is attached on top of that. As a result, the layer of wrapping rock wool covering the steel beam 28 will be 105 mm thick.

[0023] (Metal joints) The joint metal 16 has a T-shaped cross section when viewed from a horizontal plane, and is composed of a gusset plate 40 that is bolted to the side end of the steel beam 28, and a base plate 42 that is connected to the side end of the gusset plate 40 and attached to the surface of the fireproof sheet 22B on the side of the fireproof wooden column 12. To allow for thermal expansion and deformation of the fireproof sheet 22B when heated by a fire, the base plate 42 and the fireproof sheet 22B are not in close contact with each other, but a thin layer of air is provided between them.

[0024] The gusset plate 40 is butted against the web 38 at the side end of the steel beam 28 in the left-right direction, and a plate 44 is disposed on the front and rear surfaces of this butting portion, straddling the gusset plate 40 and the web 38. The plates 40, 44 and the web 38 are joined by a plurality of bolts 46 that are passed through through holes that pass through each of the plates.

[0025] The base plate 42 is fixed to the fire-resistant wooden column 12 via steel rods 48 that are embedded horizontally in the left-right direction in the fire-resistant wooden column 12. The upper end of the base plate 42 is approximately aligned with the upper end of the fire-resistant wooden column 12. The base plate 42 in this embodiment is made of a rectangular steel plate with a width of about 300 mm, a height of 600 mm, and a thickness of about 25 mm. The steel rods 48 are arranged in three locations spaced apart in the vertical direction, two locations at the front and rear of the connection between the gusset plate 40 and the base plate 42, but the present invention is not limited to this, and other layouts and quantities may be used.

[0026] The end 48A of the steel bar 48 on the base plate 42 side passes through an insertion hole provided in the base plate 42. The end 48A is threaded, and nuts 50A, 50B are screwed on both sides of the base plate 42. The end 48A is fixed to the base plate 42 by fastening the nut 50. The nut 50A arranged on the fireproof wooden column 12 side of the base plate 42 is arranged in the joint portion 22C of the fireproof covering material 22. A fireproof joint material 52 is filled around the nut 50A in the joint portion 22C. For example, a silicone-based sealant can be used for the fireproof joint material 52. A recess 54 is formed between the inside of the core material 20 and the steel bar 48. The recess 54 is filled with a grout material 56 such as non-shrink mortar. The grout material 56 is provided to suppress heat conduction from the steel bar 48 to the core material 20.

[0027] The other side 48B of the steel bar 48 passes through an anchor plate 58 arranged in the recess 54 and is screwed into a nut (not shown) on the opposite side of the fire-resistant wooden column 12. The steel bar 48 may be, for example, a fully threaded bolt, a round bar with threads cut on both ends, an anchor bolt used in the foundations of buildings, a deformed bar with threads cut on both ends, or the like.

[0028] (Fireproof coating material around metal joints) The fireproof covering material 18 is a third dry fireproof covering material of the present invention, and is provided so as to cover the surfaces of the base plate 42 and the gusset plate 40. The fireproof covering material 18 is thicker than the fireproof covering material 30 covering the steel beam 28, and the fireproof performance of the fireproof covering material 18 is higher than the fireproof performance of the fireproof covering material 30. The fireproof covering material 18 is composed of wound rock wool in a rectangular blanket shape. The wound rock wool can be made of the same material as the wound rock roll of the fireproof covering material 30 covering the steel beam 28. The wound rock wool used for the fireproof covering material 18 of this embodiment is 130 mm thick, about 700 mm high, and about 500 mm wide. When this wound rock wool is placed on the surface of the base plate 42, the entire base plate 42 is covered with this wound rock wool, and the entire surface of the gusset plate 40 is covered with the thickness of the wound rock wool together with the plate 44.

[0029] (Fireproof coating installation procedure) The procedure for installing the wrapped rock wool (fireproof coating material 18) is as follows: first, the wrapped rock wool is layered and attached to the base plate 42 fixed to the fireproof wooden column 12, and then the wrapped rock wool (fireproof coating material 30) is attached to the steel beam 28. Specifically, two layers of wrapped rock wool (65 mm thick) of the fireproof coating material 18 are layered on the base plate 42 attached to the fireproof wooden column 12. This results in a layer thickness of 130 mm of the wrapped rock wool covering the base plate 42. Note that the larger the layer thickness, the better the thermal insulation performance, so the layer thickness may be 130 mm or more. The thickness of the wrapped rock wool covering the base plate 42 is preferably 65 mm or more for a 1-hour fireproof specification and 105 mm or more for a 2-hour fireproof specification.

[0030] Regarding the method of fastening the wrapped rock wool, the first layer is fastened to the base plate 42 with a welding pin (not shown), and the second layer is fastened to the fire-resistant wooden pillar 12 with a screw with a washer (not shown). When stacking the wrapped rock wool on the base plate 42, it is desirable to make a cut in the part of the gusset plate 40 that attaches to the base plate 42 of the wrapped rock wool and stack it.

[0031] The wrapped rock wool (fire-resistant coating material 30) to be attached to the steel beam 28 is attached to the steel beam 28 so as to be in close contact with the surface of the wrapped rock wool (fire-resistant coating material 18) that has previously been layered on the base plate 42.

[0032] According to the above configuration, the same fire resistance performance as that of the fire-resistant wooden columns 12 and fire-resistant steel beams 14 alone can be secured at the column-beam joints. This ensures the fire safety of buildings using fire-resistant wooden columns 12 and fire-resistant steel beams 14. Also, a hybrid structure of wooden and steel members can be realized as a one-hour or two-hour fire-resistant structure. Furthermore, by using dry fire-resistant coating materials for the fire-resistant coating materials 18, 30 around the column-beam joints, the effort of curing can be reduced compared to wet fire-resistant coating materials, and the lack of drying time leads to a shortened construction period.

[0033] (Verification of the Effects of the Invention) Next, a fire resistance test carried out to verify the effects of the present invention and the results thereof will be described.

[0034] A test specimen simulating the above fire-resistant structure 10 was fabricated, and a fire resistance test was conducted to confirm the fire resistance performance. The fire resistance test was conducted by placing the test specimen in a furnace and heating it for 1 or 2 hours according to the standard heating curve specified in ISO834, and then allowing it to cool in the furnace for 24 hours. Test specimens 1 for the 1-hour fire resistance test and test specimen 2 for the 2-hour fire resistance test were fabricated. Figure 2 shows a schematic diagram of test specimen 1, and Figure 3 shows a schematic diagram of test specimen 2. The steel beams and metal joints of test specimens 1 and 2 were the same as those used in the above fire-resistant structure 10.

[0035] The left side of the test specimen 1 corresponds to Example 1-1 of the present invention, and the right side corresponds to Example 1-2. Example 1-1 has a thickness of 65 mm wrapped around the steel beam, and Example 1-2 has a thickness of 105 mm (two layers of 65 mm + 40 mm). In the center of the inside of the fire-resistant wooden column 12, board-shaped fire-resistant materials 26 are stacked to divide the core material into left and right, providing thermal insulation between Example 1-1 and Example 1-2.

[0036] The left side of the test specimen 2 corresponds to Example 2-1 of the present invention, and the right side corresponds to Example 2-2. Example 2-1 has a thickness of 105 mm (two layers of 65 mm + 40 mm) wrapped around the steel beam, and Example 2-2 has a thickness of 145 mm (three layers of 65 mm + 40 mm + 40 mm). In the center of the interior of the fire-resistant wooden column 12, board-shaped fire-resistant materials 26 are stacked to divide the core material into left and right, providing thermal insulation between Example 2-1 and Example 2-2.

[0037] Figure 4(1) shows the temperature measurement positions of specimen 1, (2) shows the temperature measurement results of Example 1-1, and (3) shows the temperature measurement results of Example 1-2. Figure 5(1) shows the temperature measurement positions of specimen 2, (2) shows the temperature measurement results of Example 2-1, and (3) shows the temperature measurement results of Example 2-2. Figures 4(1) and 5(1) show the maximum temperatures at each temperature measurement position. The temperature measurement results in Figures 4(2), (3), and 5(2), (3) use the maximum temperature values ​​measured at each temperature measurement position P1 to P4.

[0038] As shown in FIG. 4, in the test specimen 1 for the one-hour fire resistance test, the maximum temperature of the wooden column core material around the joints was 200°C or less in both specifications (Examples 1-1 and 1-2), and did not reach the temperature at which wood would be carbonized. In addition, no discoloration or carbonization was observed on the surface of the column core material around the joints. Furthermore, the maximum steel temperature of the steel beam was 251°C, and the maximum steel temperature of the base plate was 110°C or less, confirming the effectiveness of the fire-resistant coating material. From the above, it was confirmed that the fire-resistant coating specifications around the joints of Examples 1-1 and 1-2 have one-hour fire resistance.

[0039] As shown in FIG. 5, in the test specimen 2 for the 2-hour fire resistance test, the maximum temperature of the column core material around the joint was 200°C or less in both specifications (Examples 2-1 and 2-2), and did not reach the temperature at which wood would be carbonized. In addition, no discoloration or carbonization was observed on the surface of the column core material around the joint. Furthermore, the steel temperature of the steel beam reached a maximum of 478°C in Example 2-1, but the steel temperature of the base plate reached a maximum of 162°C, and it was confirmed that the temperature rise of the base plate portion was suppressed by the fire-resistant coating material of the base plate portion. On the other hand, in Example 2-2, the steel temperature of the steel beam reached a maximum of 606°C. This is because part of the fire-resistant coating material of the steel beam fell off during heating. However, the steel temperature of the base plate reached a maximum of 228°C, and it was confirmed that the temperature rise of the base plate portion was suppressed by the fire-resistant coating material of the base plate portion. From the above, it was confirmed that the fire-resistant coating specifications around the joints of Examples 2-1 and 2-2 had a fire resistance performance of 2 hours.

[0040] As described above, the fireproof structure for a column-beam joint according to the present invention is a fireproof structure for a column-beam joint formed by joining a fireproof wood column comprising a wood core material for supporting a load and a first fireproof covering material provided on the outside of the core material, and a fireproof steel beam comprising a steel member and a dry-type second fireproof covering material provided on the outside of the steel member, via a T-shaped metal joint consisting of a gusset plate fixed to the side end of the steel member and a base plate attached to the first fireproof covering material on the side of the fireproof wood column, and further comprising a dry-type third fireproof covering material provided on the surfaces of the base plate and the gusset plate. The fireproof performance of the third fireproof covering material is higher than that of the second fireproof covering material, so that the fireproof performance of the column-beam joint between the fireproof wood column and the fireproof steel beam is equivalent to that of the column-beam alone. In addition, dry fire-resistant coating materials reduce the effort required for curing compared to wet fire-resistant coating materials, and since they do not require drying time, they lead to shorter construction times.

[0041] In addition, according to another fire-resistant structure of a column-beam joint of the present invention, the thickness of the third fire-resistant covering material is greater than the thickness of the second fire-resistant covering material, so that the column-beam joint between a fire-resistant wood column and a fire-resistant steel beam can ensure fire resistance performance equivalent to that of the column and beam alone.

[0042] In addition, according to another fire-resistant structure of a column-beam joint of the present invention, the second fire-resistant covering material and the third fire-resistant covering material are wrapped rock wool, and therefore can be easily applied.

[0043] The "Sustainable Development Goals (SDGs)" are 17 international goals that were adopted at the United Nations Summit in September 2015. The fireproof structure of the column-beam joint according to this embodiment can contribute to the achievement of, for example, "11. Sustainable urban and human settlements" among the 17 SDGs. [Industrial Applicability]

[0044] As described above, the fire-resistant structure of the column-beam joint according to the present invention is useful for the joint between a fire-resistant wooden column and a fire-resistant steel beam, and is particularly suitable for ensuring fire resistance equivalent to that of the column and beam alone. [Explanation of symbols]

[0045] 10 Fireproofing of beam-column joints 12 Fireproof wooden pillar 14 Fireproof steel beams 16 Joint metal fittings 18 Fireproof sheathing (third fireproof sheathing) 20 Core material 22 Fireproof sheathing (first fireproof sheathing) 24 Finishing Materials 26 Fireproof materials 28 Steel beams (steel members) 30 Fireproof sheathing (secondary fireproof sheathing) 32 Flooring 34 Upper flange 36 Lower flange 38 Web 40 Gusset plate 42 Base Plate 44 Plate 46 Volts 48 steel rod 50A, 50B Nut 52 Fireproof joint material 54 Recess 56 Grout material 58 Fixing plate

Claims

1. A fireproof structure of a column-beam joint formed by joining a fireproof wooden column including a wooden core material supporting a load and a first fireproof covering material provided on the outside of the core material, and a fireproof steel beam including a steel member and a dry second fireproof covering material provided on the outside of the steel member, via a T-shaped cross-section connecting metal fitting consisting of a gusset plate fixed to a side end of the steel member and a base plate attached to the first fireproof covering material on a side of the fireproof wooden column, a dry third fire-resistant coating material provided on a surface of the base plate and the gusset plate; A fire-resistant structure for a column-beam joint, characterized in that the fire resistance of the third fire-resistant coating material is higher than the fire resistance of the second fire-resistant coating material.

2. The fireproof structure for a column-beam joint according to claim 1, characterized in that the thickness of the third fireproof coating material is greater than the thickness of the second fireproof coating material.

3. 3. A fireproof structure for a column-beam joint according to claim 1, wherein the second fireproof coating material and the third fireproof coating material are wrapped around rock wool.

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