Refractory structural material

Abstract

To provide a fire-resistant structural material capable of lengthening a fire-resistant time without thickening a burning stop part.SOLUTION: This fire-resistant structure material 1A is provided with a load support part 2 whose central part is made of wood and whose cross section is approximately rectangular, a burning stop part 3 provided outside the load support part 2, a foaming fire-resistant layer 4 provided outside the burning stop part 3, and a finish layer 5 provided outside the foaming fire-resistant layer 4. The corners of the rectangle are occupied by the spacer side 2a. The 2a of the spacer is a polymer material having a predetermined melting temperature, and the thickness of the burning stop portion 3 is within a predetermined range. When the structural refractory 1A is heated, the spacer 2a melts and flows out, creating a gap or cavity. This retards heat transfer to the wood parts.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fire-resistant structural material. [Background technology]

[0002] In wooden buildings, fire resistance is required for the structural materials that make up the columns and beams so that they do not collapse in the event of a fire. It is desirable that the center of a structural material, which supports the load, does not carbonize even when exposed to flames and the surface burns. To achieve this, for example, a fire-resistant structure has been studied that includes a fire-stopping section impregnated with a fire-retardant treatment agent and a surface layer that does not contain the fire-retardant treatment agent (Patent Document 1). This fire-resistant structure can prevent carbonization from progressing toward the center after the fire has ended by adjusting the thickness of the fire-stopping section so that the burning area at the end of the fire is the area injected with the fire-retardant treatment agent, and the fire will naturally stop burning, preventing the building from collapsing.

[0003] In addition, in order to slow down the transfer of heat, it has been devised to chamfer the corners of the core material that makes up the center of the structural material or to fill the corners with mortar (Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4958098 [Patent Document 2] Patent No. 6864996 [Patent Document 3] Patent No. 6949464 Summary of the Invention [Problem to be solved by the invention]

[0005] To extend the fire resistance time, it is conceivable to simply thicken the fire-stopping portion. However, thickening the fire-stopping portion not only reduces the indoor space but also increases the cost of wood and fire-retardant treatment chemicals, which is undesirable from the viewpoint of resource conservation. Therefore, the object of the present invention is to provide a fire-resistant structural material that can extend the fire resistance time without thickening the fire-stopping portion. [Means for solving the problem]

[0006] The present invention provides a fire-resistant structural material comprising a load-bearing portion having a central portion made of wood and a substantially rectangular cross section, a fire-stopping portion provided on the outside of the load-bearing portion, an intumescent fire-resistant layer provided on the outside of the intumescent fire-resistant layer, and a finishing layer provided on the outside of the intumescent fire-resistant layer, wherein the corners of the rectangle are occupied by spacers made of a polymeric material having a melting temperature of 150°C or less, and the thickness of the fire-stopping portion is less than 35 mm.

[0007] The present invention also provides a fire-resistant structural material comprising a load-bearing portion having a central portion made of wood and a substantially rectangular cross section, a fire-stopping portion provided on the outside of the load-bearing portion, an intumescent fire-resistant layer provided on the outside of the intumescent fire-resistant layer, and a finishing layer provided on the outside of the intumescent fire-resistant layer, wherein the corners of the rectangle are occupied by spacers made of a polymeric material having a melting temperature of 250°C or less, and the thickness of the fire-stopping portion is 35 mm or more.

[0008] When these fire-resistant structural materials are exposed to a fire, the spacers melt and flow out as the finishing layer and the fire-stopping area carbonize. When the spacers flow out, gaps or cavities form in the areas where the spacers used to be. These gaps or cavities slow the heat transfer to the load-bearing wood parts, prolonging the fire-resistance time.

[0009] The intumescent fire-resistant layer may have a thickness of 1 mm or more, which will provide a longer fire resistance time.

[0010] In the fire-resistant structural material of the present invention, the center of the load-bearing section may be made of laminated lumber with laminated lamina. If the load-bearing section is made of a single piece of square timber, cutting work is required to locate the spacer, which is time-consuming. If the load-bearing section is made of laminated lumber with laminated lamina, the spacer location can be adjusted by using a lamina with a shorter width, which is less time-consuming.

[0011] The fire stop portion may be wood impregnated with a fire retardant treatment.

[0012] The finishing layer may be made of wood and may have a thickness of 20 mm to 40 mm. The finishing layer has the purpose of preventing the intumescent fireproof layer from being obscured from the outside from the viewpoint of design, and also has the effect of increasing heat insulation by being carbonized by exposure to flames, thereby delaying the progress of carbonization toward the burn-out portion.

[0013] The fire-resistant structural material of the present invention may be a column or a beam. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a fire-resistant structural material that can extend the fire-resistant time without increasing the thickness of the fire-stop portion. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view of a fire-resistant structural material according to one embodiment of the present invention. [Figure 2] 1 is a cross-sectional view of a fire-resistant structural material according to one embodiment of the present invention. [Figure 3] 1 is a graph showing temperature changes. [Figure 4] 1 is a graph showing temperature changes. [Figure 5] 1 is a graph showing temperature changes. [Figure 6] 1 is a graph showing temperature changes. [Figure 7] FIG. 10 is a cross-sectional view of a comparative test specimen. [Figure 8]1 is a graph showing temperature changes. DETAILED DESCRIPTION OF THE INVENTION

[0016] The fire-resistant structural material of the present invention is made of wood and is intended to be used mainly as a pillar or beam, and to improve the fire resistance of such a structure. Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted.

[0017] <Fireproof structural materials> FIG. 1 conceptually illustrates a fire-resistant structural material 1A according to one embodiment of the present invention, and FIG. 2 illustrates a more specific embodiment, a fire-resistant structural material 1B. As shown in FIG. 1, the fire-resistant structural material 1A of this embodiment is a column, and includes a long, square-shaped load-bearing portion 2, a fire-stopping portion 3 disposed outside the load-bearing portion 2, an intumescent fire-resistant layer 4 disposed outside the intumescent fire-resistant portion 3, and a finishing layer 5 disposed outside the intumescent fire-resistant layer. Here, "outside" refers to the radially visible side of the fire-resistant structural material 1A. The fire-stopping portion 3 is disposed around the entire periphery of the side of the load-bearing portion 2, which forms the center of the fire-resistant structural material 1A. The intumescent fire-resistant layer 4 is disposed around the entire periphery of the intumescent fire-resistant layer 4. The finishing layer 5 is disposed around the entire periphery of the intumescent fire-resistant layer 4. In addition, although each part is depicted in Figure 1 as if it were a single piece of solid wood, Figure 1 merely shows the concept of the arrangement of each part, and in reality, as will be described later, each part may be a laminated piece of wood made by pressing multiple parts together using adhesive or the like.

[0018] The load-bearing portion 2 is a core portion that supports the load of the building. The load-bearing portion 2 is made of wood in all areas other than the corners (hereinafter referred to as the "center"), and the specific type and density of the wood may be the same as the wood used for the fire-stopping portion 3 described below, or a tree species with higher density and structural performance may be used. The size of the cross section of the load-bearing portion 2 may be 120 mm to 680 mm, 180 mm to 560 mm, or 240 mm to 440 mm as one side of a square. When the fire-resistant structural material 1A is a beam, the beam cross section may have a beam depth of 120 mm to 890 mm and a beam width of 120 mm to 480 mm.

[0019] The center of the load-bearing portion 2 may be made of laminated timber in which lamina 6 are stacked, as shown in Figure 2. At the same time, the load-bearing portion 2 may be integrated with the fire-stopping portion 3. For example, as shown in Figure 2, the lamina 6 that forms the center of the load-bearing portion 2 may be wide and extend to the outside of the load-bearing portion 2, simultaneously forming the fire-stopping portion 3. In this case, the boundary between the load-bearing portion 2 and the fire-stopping portion 3 is determined based on whether or not this portion should be included in the seismic structural calculations. The portion that is included in the structural calculations is the load-bearing portion 2. The lamina 6 are bonded together using an adhesive or the like. Resorcinol-based resin is preferred as the adhesive material.

[0020] Spacers 2a are provided at the four corners of the load support portion 2. The spacers 2a are square in cross section, and each spacer 2a extends along the length of the column. The size of the spacers 2a may be such that the length of one side is 5% to 25%, or 10% to 20%, of the length of one side of the load support portion 2.

[0021] The material constituting the spacer 2a may be a polymer material having a melting temperature of 150°C or less. The melting temperature may be 150°C or more and 300°C or less, 170°C or more and 260°C or less, or 190°C or more and 220°C or less. Alternatively, the melting temperature may be 40°C or more and 120°C or less, or 60°C or more and 80°C or less. Examples of polymer materials used for the spacer 2a include polystyrene, polyvinyl chloride, chloroprene rubber, polyethylene, polycarbonate, ABS resin, and acrylic resin.

[0022] When providing the spacer 2a, for example, an epoxy resin adhesive is applied and then the spacer 2a is clamped.

[0023] The fire-stopping portion 3 functions as a layer that stops the progress of carbonization of the fire-resistant structural material 1A in the event of a fire, and is designed to be thick enough that it will not burn up completely in its thickness direction even during a fire. Materials that make up the fire-stopping portion 3 include wood injected with a fire-retardant treatment agent, and non-combustible materials such as gypsum board, calcium silicate board, and mortar.

[0024] Generally, the greater the density of wood, the slower the heat conduction and the harder it is to burn. Therefore, when the fire-stopping portion 3 is made of wood, the density of the wood is 400 kg / m 3 It is preferable that the saturation is 450 kg / m or more. 3 More preferably, it is 480 kg / m or more. 3 The upper limit is preferably 600 kg / m or more. 3 , 580 kg / m 3 , 550 kg / m 3 Examples of wood having such a density include larch, cypress, fir, Japanese cypress, white pine, Yezo spruce, camphor tree, red pine, etc. Larch is preferred in terms of abundance of resources and market price.

[0025] The wood that forms the fire-stopping portion 3 has a density of 400 kg / m3 so that it can be easily impregnated with fire-retardant chemicals. 3 The density may be less than 390 kg / m3 may be less than 380 kg / m 3 The lower limit of the density is 250 kg / m 3 , 270 kg / m 3 , 290 kg / m 3 Examples of wood with such a density include cedar, Paulownia, and Japanese black pine. When wood with a low density is selected, it may be necessary to make the fire-stopping portion 3 thicker than when wood with a high density is selected. Cedar is suitable in terms of abundance of resources and market price.

[0026] The fire retardant treatment agent injected into the wood that constitutes the fire-stopping portion 3 can be any type, including phosphorus-based, nitrogen-based, boron-based, and halogen-based agents. The method for injecting the fire retardant treatment agent into the wood can be any method, including dipping, painting, spraying, and vacuum / pressure treatment.

[0027] The thickness of the fire-stopping portion 3 varies depending on the type of wood constituting the fire-stopping portion 3 and the desired fire resistance time. For example, if a 60-minute fire resistance is desired, the thickness is preferably 25 mm to 65 mm, and more preferably 35 mm to 55 mm. If a 90-minute fire resistance is desired, the thickness is preferably 30 mm to 70 mm, and more preferably 40 mm to 60 mm. If the melting temperature of the spacer 2a is 150°C or lower, the thickness of the fire-stopping portion is less than 35 mm. Specifically, it may be 10 mm or more but less than 35 mm, or 20 mm or more but 30 mm or less. If the melting temperature of the spacer 2a is 250°C or lower, the thickness of the fire-stopping portion is 35 mm or more. Specifically, it may be 35 mm or more but 60 mm or less, or 40 mm or more but 50 mm or less.

[0028] The fire-stopping portion 3 can be fixed to the load-supporting portion 2 by applying a resorcinol-based resin adhesive or the like and then clamping it.

[0029] The intumescent fire-resistant layer 4 is a layer containing an intumescent fire-resistant agent, such as ammonium polyphosphate.

[0030] When the fireproofing agent is a solid, the intumescent fireproof layer 4 can be formed by dispersing the fireproofing agent in a resin to prepare a coating liquid, which is then applied to the surface of the fire-stopping portion 3. Methods for curing the resin include air drying, heating, and ultraviolet irradiation. By this method, the intumescent fireproof layer 4 can be laminated on the fire-stopping portion 3.

[0031] Alternatively, as shown in FIG. 2, the intumescent fire-resistant layer 4 may be formed by laminating a preformed intumescent fire-resistant sheet 4a onto the fire-stopping portion 3. When forming the intumescent fire-resistant layer 4 into a sheet, it is preferable to prepare a liquid in which the fire-resistant agent is dispersed in resin, which can then be poured into a predetermined space to form the sheet. Methods for laminating the intumescent fire-resistant sheet 4a onto the fire-stopping portion 3 include providing a layer of adhesive or adhesive material on the back of the sheet and adhering it to the fire-stopping portion 3, fastening the sheet to the fire-stopping portion 3 by driving fixing members such as screws into the sheet, or a combination of these methods. When driving fixing members, it is preferable to use fixing members with a length shorter than the thickness of the fire-stopping portion 3 (i.e., a length that does not penetrate the fire-stopping portion 3) so as not to reach the fire-resistant object. Alternatively, the finishing layer 5 (described later) may be laminated onto the intumescent fire-resistant sheet 4a, and then fixing members may be driven into the finishing layer 5 side to simultaneously fasten the finishing layer 5 and the intumescent fire-resistant sheet 4a to the fire-stopping portion 3. Because the joints of the sheets at the corners of the fire-stopping portion 3 are likely to be weak points in terms of fire resistance, it is preferable to extend one side of the sheet and attach it, as shown in Figure 2. The extension length may be 1 mm or more and 5 mm or less, or 2 mm or more and 4 mm or less. By using these methods, the intumescent fire-resistant layer 4 can be laminated on the surface of the fire-stopping portion 3 without any other fire-resistant layer in between.

[0032] The thickness of the intumescent fire-resistant layer 4 varies depending on the required fire resistance time. For example, if 60 minutes of fire resistance is required, the thickness of the intumescent fire-resistant layer 4 is 1 mm or more. This thickness may be 1.5 mm or more and 3.0 mm or less, or 2.0 mm or more and 2.5 mm or less. If 90 minutes of fire resistance is required, the thickness of the intumescent fire-resistant layer 4 is preferably 2 mm or more, and may be 2.5 mm or more and 6.0 mm or less, or 3.0 mm or more and 5.0 mm or less.

[0033] The finishing layer 5 is also called the decorative layer, and is the layer that building users come into contact with on a daily basis. Since the finishing layer 5 may be touched by hand, if the fire-stopping portion 3 contains a fire-retardant treatment agent, it acts as a lid to prevent the fire-retardant treatment agent from leaking out. Materials that can be used to make the finishing layer 5 include the same wood as the wood that makes up the fire-stopping portion 3, and cedar or larch is particularly preferred.

[0034] The thickness of the finishing layer 5 is preferably 20 mm to 40 mm, more preferably 25 mm to 35 mm, and even more preferably 28 mm to 33 mm. Since manufacturing the fire-stop portion 3 is time-consuming and expensive, in order to improve the fire resistance of the fire-resistant structural material 1A, by setting the thickness of the finishing layer 5, which is the outermost layer and can be manufactured relatively easily, within the above range, it is possible to easily buy time for heat to be transmitted to the interior.

[0035] 2, the finishing layer 5 can be provided by attaching four finishing plates 5a having the above-mentioned thickness to each side of the intumescent fire-resistant layer 4. The finishing plates 5a can be fixed to the intumescent fire-resistant layer 4 and the fire-stopping portion 3 by applying a resorcinol-based resin adhesive or the like and then pressing them together, or by using metal fixing members such as screws or nails.

[0036] The typical carbonization rate of wood is approximately 0.6 mm / min, for example. In this case, the required thickness of the finishing layer 5 can be calculated by multiplying this rate by the desired fire resistance time. For example, if a 30-minute fire resistance time is desired, the finishing layer 5 should be made 0.6 mm / min x 30 = 18 mm thick. If a 10 mm thick decorative layer was previously used as the finishing layer 5, the thickness of the finishing layer 5 in this embodiment would be 10 mm + 18 mm = 28 mm. On the other hand, if the finishing layer 5 is too thick, the burning time as a combustible material will be longer, increasing the thermal impact on the load-bearing portion 2. Therefore, the upper limit of the thickness of the finishing layer 5 is preferably the value described above.

[0037] <Effects> Generally, structural materials with polygonal cross sections are prone to burn at their corners, which receive heat from two sides. The fire-resistant structural material 1A of this embodiment has spacers 2a provided inside the corners. When the fire-resistant structural material 1A is exposed to flames, the spacers 2a, which are heated through the fire-stopping portion 3 and reach their melting temperature during the carbonization process of the finishing layer 5 and fire-stopping portion 3, melt and flow out. When the spacers 2a flow out, gaps form in the areas previously occupied by the spacers 2a, or these areas become hollow. These gaps or hollows slow the transfer of heat to the wood portion of the load-bearing portion 2, thereby extending the fire-resistant time.

[0038] Before the fire-stop portion 3 begins to carbonize, the intumescent fire-resistant layer 4 foams and expands due to the heat of the fire, providing a heat insulating effect. The fire-stop portion 3 burns and carbonizes, and the carbonization gradually spreads inside the fire-stop portion 3 toward the load-bearing portion 2, but the entire thickness does not burn, and the fire stops inside the fire-stop portion 3 some time after the fire is extinguished.

[0039] As described above, the function of the spacer 2a and the function of the intumescent fire-resistant layer 4 make it possible to extend the fire-resistant time of the fire-resistant structural material 1A without increasing the thickness of the fire-stop portion 3.

[0040] Furthermore, if the center of the load-bearing portion 2 of the fire-resistant structural material 1A is made of laminated timber with laminated lamina 6, the effort required to fabricate the fire-resistant structural material 1A is reduced. That is, if the load-bearing portion 2 is made of a single piece of square timber, cutting is required to locate the spacers 2a, which is time-consuming, and it is also necessary to prevent the lamina 6 from shifting out of position. In contrast, if the load-bearing portion 2 is made of laminated timber with laminated lamina 6, the adjustment of the spacers 2a can be achieved by preparing a lamina with a shorter width, as shown in Figure 2, which reduces the effort required for fabrication.

[0041] Furthermore, the provision of the finishing layer 5 prevents the intumescent fire-resistant layer 4 from being obscured from the viewpoint of design, and also increases the insulating properties by being carbonized by exposure to flames, thereby slowing the progression of carbonization to the burn-out area. In particular, when the thickness of the finishing layer 5 is 30 mm or less, it does not hinder the expansion of the intumescent fire-resistant layer 4, and the performance of the intumescent fire-resistant layer 4 is fully exhibited.

[0042] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, although the above embodiments show an aspect in which the load support portion 2 has a square cross section, the load support portion may have any cross section as long as it is rectangular, and may also be rectangular. [Example]

[0043] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0044] <60-minute fire resistance test> (Preparation of test specimen) A fire-resistant structural member with the structure shown in Figure 2 was fabricated. Starting from the center, it consisted of a load-bearing section (larch wood; 180 mm square), a fire-stop section (larch wood; 30 mm thick), a foam fireproofing layer (a sheet made of ammonium polyphosphate; 1 mm thick), and a finishing layer (larch wood; 20 mm thick). More specifically, the load-bearing section and the fire-stop section were made up of eight lamina (each 30 mm thick), some of which were common. The two lamina at each end constituted the fire-stop section. The six lamina in the middle constituted the load-bearing section, and the four in the middle spanned both the load-bearing section and the fire-stop section. The two lamina at each end, which sandwiched the four lamina, were short in width, leaving space at the corners of the load-bearing section. One of the spacers described below was installed in this space. "Styrofoam" [registered trademark] (polystyrene), melting temperature: approx. 100°C "Plaban" (polyvinyl chloride), melting temperature: approx. 210°C "Rubber" (chloroprene rubber), heat resistance temperature: approx. 70°C

[0045] Eight thermocouples S1 to S8 were installed between the load-supporting part and the flame-extinguishing part, as shown in Figure 2. The installation locations were the corners closest to the center of each spacer (four points: S1, S3, S5, S7) and the midpoints between the four corners of the load-supporting part (i.e., the points farthest from the center of the spacer) (four points: S2, S4, S6, S8).

[0046] The fire-resistant structural material shown in Figure 2 is called "Specimen A," and the fire-resistant structural material shown in Figure 2 with a 40mm thick flame-stopping section is called "Specimen B." In Specimen B, the two lamina at both ends of the eight lamina in Specimen A were replaced with two lamina with a thickness of 20mm. The dimensions of Specimen A and B, as well as Specimen C and D described below, are summarized in Table 1. The thickness of each specimen (length in the depth direction shown in Figure 2) is 700mm.

[0047] [Table 1]

[0048] The above three types of spacers were provided for each of the test specimen dimensions A and B. Test specimens 1 to 6 shown below were fabricated by combining the test specimen dimensions and spacers. Test piece 1 = Test piece size A + "Styrofoam" Test piece 2 = Test piece size B + "Styrofoam" Test piece 3 = Test piece size A + "Plastic board" Test piece 4 = Test piece size B + "Plastic board" Test piece 5 = Test piece size A + "Rubber" Test piece 6 = Test piece size B + "Rubber"

[0049] (Test Method) Specimens 1 to 6 were heated in a refractory furnace for 60 minutes so that the temperatures on all four sides followed the ISO 834 curve. Heating was carried out from one side.

[0050] (Judgment method) The results of the fire test were judged both visually and by temperature. Visual inspection: The surfaces of the load-bearing parts were visually inspected to see if they were carbonized at any point. Temperature determination: We checked whether the temperatures of all eight thermocouples exceeded 260°C, which is said to be the carbonization temperature of wood.

[0051] (result) Visual inspection results The load-bearing parts of specimens 1, 2, and 4 to 6 were not burned. In specimen 3, not only the part directly hit by the burner flame but also other parts of the body were burned up to the load-bearing parts. Temperature determination results In specimens 1, 2, and 4 to 6, the temperature of none of the eight thermocouples reached 260°C. In specimen 3, the temperature of the thermocouple on the side that was directly hit by the burner flame reached 260°C. Figures 3 to 5 show the temperature changes over time for representative thermocouples.

[0052] <90-minute fire resistance test> A 90-minute fire resistance test was conducted using "Plastic board" as the spacer, which had been found to have burned in the load-bearing section in the 60-minute fire resistance test. As shown in "Specimen Dimensions C" in Table 1, Specimen 7 was prepared in the same manner as Specimen 4, except that the thickness of the foam fire-resistant layer was set to 2 mm.

[0053] (Test Method) Specimen 7 was heated in a refractory furnace for 90 minutes so that the temperature on all four sides followed the ISO 834 curve. Heating was carried out from one side.

[0054] (Judgment method and results) The results of the fire resistance test were judged both visually and by temperature, just like the 60-minute fire resistance test. Visual inspection results In specimen 7, the load-bearing part was not burned. Temperature determination results In specimen 7, the temperature of all thermocouples never reached 260°C. Figure 6 shows the temperature changes over time for all thermocouples.

[0055] <Fire resistance test of specimen without spacer> A 60-minute fire resistance test was conducted on a specimen without a spacer. A structural member (reference numeral 10) was fabricated with the structure and dimensions shown in Figure 7. From the center, it consists of a load-bearing portion (cedar wood; 120 mm square), a fire-stopping portion (larch wood; 30 mm thick), a foam fire-resistant layer (a sheet made of ammonium polyphosphate; 1 mm thick), and a finishing layer (larch wood; 30 mm thick). The load-bearing portion is made of solid wood. The thickness (length in the depth direction shown in Figure 7) is 700 mm.

[0056] Eight thermocouples S1 to S8 were installed between the load-bearing section and the flame-extinguishing section, as shown in Figure 7. They were installed at eight locations in total: the four corners of the load-bearing section and four locations in the center of each side. The structural material shown in Figure 7 is called "specimen size D." The dimensions of specimen size D are as shown in Table 1. The specimen prepared here is called specimen 8.

[0057] (Test Method) Specimens 1 to 6 were heated in a refractory furnace for 60 minutes so that the temperatures on all four sides followed the ISO 834 curve. Heating was carried out from one side.

[0058] (Judgment method and results) The results of the fire resistance test were judged both visually and by temperature, similar to the 60-minute fire resistance test using specimens with spacers. Visual inspection results In specimen 8, the load-bearing part where the burner flame had directly hit was burned. Temperature determination results In specimen 8, the temperature reached 260°C at several thermocouples, mainly in the area directly hit by the burner flame. Figure 8 shows the temperature changes over time at each thermocouple. [Industrial Applicability]

[0059] The present invention can be used in wooden buildings. [Explanation of symbols]

[0060] 1A, 1B...fire-resistant structural material, 2...load-bearing part, 2a...spacer, 3...fire-stop part, 4...foam fire-resistant layer, 4a...foam fire-resistant sheet, 5...finishing layer, 5a...finishing board, 6...lamina, 10...structural material, S1 to S8...thermocouples.

Claims

1. a load-bearing portion having a central portion made of wood and a substantially rectangular cross section; a flame-stopping portion provided on the outer side of the load-bearing portion; an intumescent fire-resistant layer provided on the outside of the fire-stopping portion; A fire-resistant structural material comprising: a finishing layer provided on the outside of the intumescent fire-resistant layer; the corners of the rectangle are occupied by spacers; the spacer is a polymer material having a melting temperature of 150°C or less, A fire-resistant structural material in which the thickness of the fire-stopping portion is less than 35 mm.

2. a load-bearing portion having a central portion made of wood and a substantially rectangular cross section; a flame-stopping portion provided on the outer side of the load-bearing portion; an intumescent fire-resistant layer provided on the outside of the fire-stopping portion; A fire-resistant structural material comprising: a finishing layer provided on the outside of the intumescent fire-resistant layer; the corners of the rectangle are occupied by spacers; the spacer is a polymer material having a melting temperature of 250°C or less, A fire-resistant structural material in which the thickness of the fire-stopping portion is 35 mm or more.

3. 3. The fire-resistant structural material according to claim 1, wherein the intumescent fire-resistant layer has a thickness of 1 mm or more.

4. 3. The fire-resistant structural material according to claim 1, wherein the central portion of the load-bearing portion is made of laminated wood in which lamina are stacked.

5. 3. The fire-resistant structural material according to claim 1, wherein the fire-stopping portion is made of wood impregnated with a fire-retardant agent.

6. the finish layer is wood; 3. The fire-resistant structural material according to claim 1, wherein the thickness of the finishing layer is 20 mm to 40 mm.

7. 3. The fire-resistant structural material according to claim 1, which is a pillar or a beam.

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