Covering material

Abstract

To provide a covering material that can be easily applied to existing steel members and has high fire resistance.SOLUTION: The present invention relates to a covering material 20 that covers a steel member 10. The covering material 20 is formed from a plurality of part covering materials 21. Each part covering material 21 has a laminated structure in which a burn-off covering layer 25 made of solid wood that forms the surface of the covering material 21 and a fire-resistant covering layer 26 made of solid wood that is positioned between the steel member 10 and the burn-off covering layer 25 are laminated. The part covering materials 21 can be joined together to be integrated so as to cover the surface of the steel member 10. The part covering materials 21 are provided with a fire-resistant foam material 29 that closes joint portions 27 of the joints.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a coating material. [Background technology]

[0002] Various types of materials have been proposed that exhibit fire resistance, such as covering materials for covering the surfaces of steel members and fire-resistant coated structural materials in which steel members are covered with such covering materials. For example, the present applicant has previously proposed a fire-resistant structural material comprising a steel member and a fire-resistant coating layer and a burn-off coating layer made of pure wood covering the steel member, in which the burn-off coating layer burns and is burned off when exposed to flames (Patent Document 1).

[0003] Patent Document 2 discloses a fire-resistant coating structure that includes a steel member and a plurality of wooden coating materials surrounding the steel member, and a backing plate for closing the joint where the end faces of adjacent wooden coating materials butt together is provided on the steel member side. Patent Document 3 discloses a fire-resistant structure comprising a steel member, an air layer surrounding the steel member, and a wood fire-resistant covering material surrounding the air layer, the wood fire-resistant covering material having three or more flame penetration prevention corners and fire-resistant material facing the air layer and connecting adjacent flame penetration prevention corners. Patent Document 4 discloses a fire-resistant covering structure comprising a steel pipe, a plurality of wood fire-resistant covering materials arranged around the steel pipe, and corner base materials supporting adjacent wood fire-resistant covering materials, the corner support materials having a pair of flange portions that are bent and attached along the corners where the ends of the adjacent wood fire-resistant covering materials abut. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-112906 [Patent Document 2] Japanese Patent Publication No. 2022-172488 [Patent Document 3] Patent No. 7287562 [Patent Document 4] Japanese Patent Publication No. 2023-084597 Summary of the Invention [Problem to be solved by the invention]

[0005] When the covering material is composed of multiple covering parts, as in Patent Documents 2 to 4, it is effective in that it can be applied to existing steel members such as pillars, and that it is not necessary to transport to the construction site a covering structure in which steel members have been pre-covered with a covering material. However, when the covering material is composed of multiple wooden covering parts, the fire resistance tends to decrease, and there are cases where burning continues due to burning in or remaining red heat. The techniques of Patent Documents 1 to 4 have room for improvement in terms of achieving both ease of coating construction and fire resistance.

[0006] An object of the present invention is to provide a covering material that can be easily applied to existing steel members and has high fire resistance. [Means for solving the problem]

[0007] The present invention provides a covering material for covering steel members, the covering material being formed from a plurality of part covering materials, each of which has a laminated structure in which a burn-off covering layer made of solid wood forms the surface of the covering material, and a fire-resistant covering layer made of solid wood is positioned between the steel member and the burn-off covering layer, the part covering materials can be joined together to form an integrated structure covering the surface of the steel member, and the part covering materials are provided with a fire-resistant foam material that seals the joints of the joints. [Effects of the Invention]

[0008] According to the present invention, it is possible to easily apply a covering to an existing steel member and to provide a covering material with high fire resistance. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view schematically showing a fire-resistant structural material equipped with an embodiment of the covering material of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 3 is a cross-sectional view of the part covering material shown in FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view of the joint shown in FIG. [Figure 5] FIG. 5 is a view corresponding to FIG. 1, showing another embodiment of the dressing material of the present invention. [Figure 6] FIG. 6 is a perspective view of a fire-resistant structure equipped with yet another embodiment of the cladding material of the present invention. [Figure 7] 7(a) is a view corresponding to FIG. 2 showing the fire-resistant structural material of Comparative Example 1, and FIG. 7(b) is a view corresponding to FIG. 4 showing the joint of the covering material of Comparative Example 1. FIG. [Figure 8] 8(a) to 8(c) are diagrams showing the measurement positions of temperature changes when combustion test I was carried out on the fire-resistant structural material. [Figure 9] 9(a) to 9(d) are graphs showing the results of measuring the temperature of the fire-resistant structural material of Example 1 when combustion test I was carried out on the fire-resistant structural material. [Figure 10] 10(a) to 10(d) are graphs showing the results of measuring the temperature of the fire-resistant structural material of Comparative Example 1 when Combustion Test I was carried out on the fire-resistant structural material. [Figure 11] FIG. 11 is an image showing the state of the fire-resistant structural materials of Example 1 and Comparative Example 1 after the combustion test. [Figure 12] FIG. 12 is an image of cross section I of the fire-resistant structural materials of Example 1 and Comparative Example 1 after the combustion test. [Figure 13] 13(a) to 13(f) are cross-sectional views showing the joints of the covering materials of Examples 2 to 7. FIG. [Figure 14] FIG. 14 is an explanatory diagram showing the dimensions of each part of the covering materials of Examples 2 to 7. [Figure 15]15(a) and (b) are diagrams showing the measurement positions of temperature changes when combustion test II was carried out on the coating materials of Examples 2 to 7. FIG. [Figure 16] FIG. 16 is a graph showing the results of measuring the temperature at cross section I when combustion test II was carried out on the coating materials of Examples 2 to 7. [Figure 17] FIG. 17 is a graph showing the results of measuring the temperature at cross section II when combustion test II was carried out on the coating materials of Examples 2 to 7. [Figure 18] 18(a) to 18(f) are images showing the state of the coating materials of Examples 2 to 7 after the combustion test. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below based on preferred embodiments thereof. A fire-resistant structural material 1 equipped with a preferred embodiment of the covering material of the present invention is shown in Fig. 1. Fig. 1 shows a perspective view of the fire-resistant structural material 1. The fire-resistant structural material 1 of this embodiment is a structural square timber used as a beam or column in a building. The fire-resistant structural material 1 includes a steel member 10 and a covering material 20 that covers the steel member 10.

[0011] The steel member 10 can be a steel load-bearing part such as a beam, a column, a floor, or a wall. The cross-sectional design of the load-bearing part is such that it is structurally safe against long-term loads (long-term loads) such as dead loads, live loads, and snow loads. Such cross-sectional designs are well known. The steel member 10 shown in FIG. 1 has a rectangular cross section. The vertical and horizontal lengths of the steel member 10 in the cross section of the fire-resistant structural material 1 can be changed as appropriate depending on the shape or size of a load-bearing part such as a beam or a column. For example, the steel member 10 can be a square steel pipe, an H-shaped steel, a square steel, a flat steel, a channel steel, or the like. The steel member 10 may also have a shape other than these, and any steel member that can be coated with a coating material 20 can be used without any particular restrictions.

[0012] The covering material 20 covers the steel member 10. In this embodiment, the covering material 20 covers four side surfaces of the steel member 10, which is a column A, along the axial direction. The covering material 20 may cover three axial side surfaces of the steel member 10. As shown in Fig. 5, when the steel member 10 is a beam B, the upper side of the steel member 10 may be covered by placing, for example, a floor or the like on the upper side of the fire-resistant structural material 1 on which the covering material 20 is not formed.

[0013] 2 is a schematic diagram showing a cross section (transverse cross section) in a direction perpendicular to the axial direction of the fire-resistant structural material 1. The axial directions of the covering material 20 and the part covering material 21 are the same as the axial direction of the fire-resistant structural material 1. The covering material 20 is formed by a plurality of part covering materials 21. The covering material 20 of this embodiment has four part covering materials 211, 212, 213, and 214, and these part covering materials 211, 212, 213, and 214 cover the outer peripheral surface of the steel member 10. The number of part coating materials 21 provided in the coating material 20 is not particularly limited, and may be any number that can adequately cover a part or the entire outer circumferential surface of the steel member 10 .

[0014] FIG. 3 shows a schematic cross section of the part covering material 21 in a direction perpendicular to the axial direction of the covering material 20. In the covering material 20, each part covering material 21 has a laminated structure in which a burn-resistant covering layer 25 made of solid wood forms the surface of the part covering material 21, and a fire-resistant covering layer 26 made of solid wood is positioned between the steel member 10 and the burn-resistant covering layer 25. That is, in the part covering material 21, the fire-resistant covering layer 26 forms the inner layer, and the burn-resistant covering layer 25 forms the outer layer.

[0015] The burn-dissipating coating layer 25 covers the fire-resistant coating layer 26. The burn-dissipating coating layer 25 is configured to burn and be destroyed when exposed to a flame. As a result, the coating material 20 of this embodiment can prevent the fire-resistant coating layer 26 from becoming red-hot. Although the reason for this is not entirely clear, as described in paragraph

[0017] of Patent Document 1, it is presumed that the surface of the fire-resistant coating layer 26 can be kept smooth for a while after combustion begins, and that the time during which the thermal decomposition reaction or oxidation reaction of the fire-resistant coating layer 26 occurs can be shortened during the time the fire-resistant structural material 1 is burning, making it less likely for cracks to occur in the fire-resistant coating layer 26 and preventing it from continuing to become red-hot.

[0016] Furthermore, even if cracks or the like occur in the burn-dissipating coating layer 25 due to a thermal decomposition reaction or an oxidation reaction, and red heat is generated in the cracks, the burn-dissipating coating layer 25 is burned away, and therefore the burn-dissipating coating layer 25 does not continue to be red-heated. Therefore, the red heat of the burn-dissipating coating layer 25 can be prevented from being transmitted to the fire-resistant coating layer 26. This also contributes to suppressing the red heat of the fire-resistant coating layer 26.

[0017] The thickness of the burn-off coating layer 25 is preferably less than 25 mm, which allows the burn-off coating layer 25 to be burned off more reliably and the red heat of the fire-resistant coating layer 26 to be further suppressed. From the same viewpoint as above, the thickness of the burn-resistant coating layer 25 is preferably less than 25 mm, more preferably less than 20 mm. Furthermore, from the viewpoint of delaying the onset of the thermal decomposition reaction or oxidation reaction of the fire-resistant coating layer 26, the thickness of the burn-resistant coating layer 25 is preferably 10 mm or more, more preferably 15 mm or more.

[0018] The coating material 20 of this embodiment preferably satisfies the following criteria (1) and (2) when a 60-minute combustion test using standard heating in accordance with ISO834-1 is conducted on a fire-resistant structural material 1 in which a steel member 10 is coated with the coating material 20 and a comparative coating material in which the burnable coating layer 25 of the fire-resistant structural material is replaced with a fire-resistant coating layer 26. Criterion (1): Immediately after heating, the rate of mass loss of Fire-Resistant Structural Material 1 is greater than that of the Comparative Structural Material. Criterion (2): Within 180 minutes after the end of heating, the rate of mass loss of Fire-Resistant Structural Material 1 is smaller than that of the Comparative Structural Material. The fact that the fire-resistant structural material 1 satisfies the criterion (1) is considered to mean that the burn-resistant coating layer 25 is more likely to burn when exposed to a flame. In addition, the fact that the fire-resistant structural material 1 satisfies the criterion (2) is considered to mean that the thermal decomposition reaction and oxidation reaction of the fire-resistant coating layer 26 settle at an earlier stage after the burn-resistant coating layer 25 is burned. Therefore, the fire-resistant structural material 1 that satisfies the criterion (1) and (2) can further suppress the red heat of the fire-resistant coating layer 26.

[0019] To describe the comparative structural material in more detail, the comparative structural material has the same configuration as the fire-resistant structural material 1, except that the burn-wicking coating layer 25 in the fire-resistant structural material 1 is replaced with a fire-resistant coating layer 26. The cross-sectional dimensions of the comparative structural material are the same as those of the fire-resistant structural material 1. The comparative structural material can also be manufactured by replacing the burn-wicking coating layer 25 and the fire-resistant coating layer 26 in the fire-resistant structural material 1 with a fire-resistant coating layer 26 having the same thickness as the combined thickness of the burn-wicking coating layer 25 and the fire-resistant coating layer 26.

[0020] The mass loss rate can be measured, for example, as follows. <Method for measuring mass loss rate> First, a 60-minute combustion test is conducted using standard heating in accordance with ISO 834-1 on Fire-Resistant Structural Material 1 and the comparative structural material. During this test, the mass change of the fire-resistant structural material is measured. Then, the mass of the structural material at time T minutes after the start of heating is W, and the mass at time T one minute after time T is Δ The mass of the structural material at W Δ Then, calculate the mass loss rate using the following formula: Mass reduction rate (kg / min)=(WW Δ ) / (T Δ -T) When calculating the mass loss rate immediately after the end of heating, T should be set to 60 (minutes).

[0021] From the viewpoint of making it easier for the fire-resistant coating layer 26 to remain when the fire-resistant structural material 1 burns and improving the fire resistance of the fire-resistant structural material 1, the thickness of the fire-resistant coating layer 26 is preferably 60 mm or more, and more preferably 75 mm or more. Furthermore, from the viewpoint of making use of the thermal conductivity of the steel members 10 and the heat absorption ability due to the influence of their heat capacity, and improving the fire-stopping effect of the wood, the thickness of the fire-resistant coating layer 26 is preferably 95 mm or less, and more preferably 90 mm or less.

[0022] In the covering material 20, the fire-resistant covering layer 26 and the burn-off covering layer 25 are made of wood materials made of pure wood. In this specification, pure wood means wood that does not contain flame retardants, non-combustible materials, inorganic materials, etc.

[0023] Examples of pure wood that can form the fire-resistant coating layer 26 include laminated lumber, lumber, cross-laminated timber (CLT), laminated veneer lumber (LVL), parallel strand lumber (PSL), and plywood. CLT and laminated lumber may be formed by stacking multiple lamina with rectangular cross sections in the short direction, with the vertices of the rectangles overlapping. Examples of pure wood species that can form the fire-resistant coating layer 26 include larch, Douglas fir, red pine, spruce, white birch, cypress, Japanese cypress, zelkova, Scots pine, and radiata pine, with larch being preferred.

[0024] Examples of pure wood that can be used to form the fire-resistant coating layer 25 include laminated lumber, lumber, cross-laminated timber (CLT), laminated veneer lumber (LVL), parallel strand lumber (PSL), and plywood. CLT and laminated lumber may be formed by stacking multiple lamina with rectangular cross sections in the short direction, with the vertices of the rectangles overlapping. Examples of pure wood species that can be used to form the fire-resistant coating layer 25 include cedar, fir, SPF, and balsa, with cedar being preferred.

[0025] Various known adhesives conventionally used in the manufacture of fire-resistant structural materials can be used to bond the fire-resistant coating layer 26 and the burn-off coating layer 25, and to bond the lamina that make up the fire-resistant coating layer 26 and the burn-off coating layer 25. Examples include resorcinol resin adhesives, resorcinol-phenol resin adhesives, aqueous polymer isocyanate resin adhesives, polyurethane adhesives, and vinyl acetate adhesives. Of these, resorcinol resin adhesives are preferred from the viewpoint of further suppressing red heat.

[0026] The covering material 20 is formed by disposing part covering materials 21 on the surface of the steel member 10, and at least partially covering the surface of the steel member 10. As shown in Figures 1 and 2, the part covering materials 21 can be joined together to form an integrated structure so as to cover the surface of the steel member 10. 2 and 3, the part covering material 21 of this embodiment has a substantially L-shape in a cross section taken along an orthogonal axis. As shown in FIG. 3, the part covering material 21 in this cross section has two sides a and b that intersect at a right angle. A first part joint 22 is formed at the end of one side a, which extends away from the right-angled corner, and a second part joint 23 is formed at the end of the other side b, which also extends away from the right-angled corner. The first part joint 22 has a portion on the front side of the part covering material 21 that protrudes more than the portion on the back side, and the second part joint 23 has a portion on the back side of the part covering material 21 that protrudes more than the portion on the front side. The back side of the part covering material 21 faces the steel member 10. 3 and 4, each of the first and second part-joints 22, 23 has a generally L-shape in which a convex portion and a concave portion are aligned in the thickness direction of the covering material 20 when viewed in an orthogonal cross section. Multiple part-covering materials 21 can be fitted together with the convex portion of the first part-joint 22 butting against the concave portion of the second part-joint 23 and the concave portion of the first part-joint 22 butting against the convex portion of the second part-joint 23. This allows the first part-joint 22 of one part-covering material 21 to be joined with the second part-joint 23 of another part-covering material 21 to integrate the multiple part-covering materials 21.

[0027] As shown in Fig. 4, a seam 27 is formed by joining multiple part covering materials 21 together. The part covering material 21 is provided with a fire-resistant foam material 29 that closes the seam 27. The fire-resistant foam material 29 is provided at one of the part joints 22, 23 of the part covering material 21. In a cross section of the covering material 20 formed by joining multiple part covering materials 21 together, the fire-resistant foam material 29 closes at least a portion of the seam 27. From the perspective of further improving fire resistance, it is preferable that the fire-resistant foam material 29 closes the seam 27 over the entire length of the part covering material 21 in the axial direction of the part covering material 21. The fire-resistant foam material 29 is joined to the part joints 22, 23 by joining means such as a stapler or adhesive tape. Furthermore, the part joints 22, 23 where the fire-resistant foam material 29 is provided preferably have a recess formed in a protruding portion on the front or back side of the part covering material 21 to accommodate the fire-resistant foam material 29. This allows the fire-resistant foam material 29 to more effectively seal the joints 27.

[0028] Examples of the fire-resistant foam material 29 include known materials (e.g., foamable fire-resistant paint and foamable fire-resistant sheet material) that expand when exposed to heat and the temperature rises, with the expanded portion functioning as a heat insulating layer. Among these, those containing thermally expandable graphite are preferred.

[0029] As shown in Fig. 4, the multiple part covering materials 21 in this embodiment are joined together and secured to one another by fasteners 24. As a result, the multiple part covering materials 21 are secured to the steel member 10 in an integrated state surrounding the periphery of the steel member 10. The part covering materials 21 are secured to one another by, for example, multiple fasteners 24 arranged at intervals along the axial direction of the covering material 20. There are no particular restrictions on the spacing between the fasteners 24 in the axial direction. The fastening device 24 may be, for example, a screw, a nail, or a staple. In this embodiment, the part coverings 21 are fastened together with screws. That is, the covering 20 includes fastening devices 24 at the joints 28 of the multiple part coverings 21, which penetrate the laminated structure of the burn-off covering layer 25 and the fire-resistant covering layer 26. Using these fastening devices 24 improves the efficiency of the workability during covering application. The fastening devices 24 are driven into the thickness direction Y of the covering 20, penetrating the first part joint 22 through the dowel holes and reaching a portion of the second part joint 23. That is, the fastening devices 24 extend from the burn-off covering layer 25 to at least a portion of the fire-resistant covering layer 26 in the thickness direction. In the covering 20 of this embodiment, the dowel holes into which the fastening devices 24 are driven are blocked by wooden dowels 24a.

[0030] The covering material 20 of this embodiment has a plurality of part covering materials 21 that can be joined together, and therefore can be easily applied to covering existing steel members 10 such as pillars. Furthermore, in the covering material 20 of this embodiment, the fire-resistant foam material 29 foams in the event of a fire, filling gaps in the joints 27. As a result, it is possible to effectively prevent burning through the joints 27 or residual red heat in the joints 27, thereby achieving excellent fire resistance.

[0031] As shown in Fig. 2, in the covering material 20 of this embodiment, the substantially L-shaped corners of the part covering material 21 are arranged at the corners of the steel members 10, whose cross section is rectangular. From the viewpoint of further suppressing burning through the joint portions 27 or remaining red heat at the joint portions 27, it is preferable that the joint portions 27 of the covering material 20 are located outside the corners of the covering material 20. In this embodiment, the joint portions 27 are located between the corners of the steel members 10 that are adjacent in the circumferential direction of the steel members 10. More specifically, the joint portions 27 are located midway between the corners of the steel members 10 that are adjacent in the circumferential direction.

[0032] From the viewpoint of further improving fire resistance, it is preferable that the joint portion 27 be bent in a crank shape as shown in Fig. 4 when viewed in cross section in the orthogonal direction, i.e., when viewed in cross section in the thickness direction Y of the covering material 20. This makes it difficult for the rear side of the joint portion 27, i.e., the steel member 10 side, to burn.

[0033] In the covering material 20, the first and second part joints 22, 23 of adjacent part covering materials 21 are fitted together to form a joint 28 where these part joints 22, 23 face each other. That is, in the joint 28, the first and second part joints 22, 23 face each other across a seam 27. As shown in FIG. 4 , the coating material 20 of this embodiment has a front-side facing portion 28a that faces each other on the front side of the coating material 20 and a back-side facing portion 28b that faces each other on the back side of the front-side facing portion 28a. In a cross-sectional view of the coating material 20 in the thickness direction Y, the front-side facing portion 28a includes a burn-off coating layer 25 and is formed by a protruding portion in the first-part seam 22 and a corresponding recess in the second-part seam 23. In a cross-sectional view of the coating material 20 in the thickness direction Y, the back-side facing portion 28b is formed by a protruding portion in the second-part seam 23 and a corresponding recess in the first-part seam 22. In this embodiment, the front-side facing portion 28a and the back-side facing portion 28b are offset in the joining direction. The joining direction X is the direction in which the first-part seam 22 and the second-part seam 23 are aligned in the seam 28 and is perpendicular to the thickness direction Y of the coating material 20.

[0034] The position of the fire-resistant foam material 29 in the joint portion 28 is not particularly limited, and it can be disposed in either or both of the front surface side facing portion 28a and the back surface side facing portion 28b. When the positions of the front-side facing portion 28a and the back-side facing portion 28b are misaligned in the joining direction X, it is preferable that the fire-resistant foam material 29 be provided so as to be located at the front-side facing portion 28a, from the viewpoint of further improving fire resistance. This makes it possible to further suppress burning into the joint portion 27.

[0035] From the viewpoint of further improving fire resistance, it is preferable that the dimensions of each portion of the joint 28 in the thickness direction Y of the covering material 20 be within the following ranges. The thickness T2 of the front surface-side opposing portion 28a is preferably 40% to 80% and more preferably 60% to 70% of the thickness T1 of the covering material 20. These thicknesses T1 and T2 are lengths in the thickness direction Y of the covering material 20. The length L1 between the seam 27 of the front surface side facing portion 28a and the seam 27 of the back surface side facing portion 28b in the joining direction X is preferably 20 mm to 100 mm, more preferably 30 mm to 60 mm. The length L2 of the fire-resistant foam material 29 in the thickness direction Y of the covering material 20 is preferably 30% to 80% of the thickness T2 of the front surface-side opposing portion 28a, and more preferably 50% to 60%. The width L3 of the fire-resistant foam material 29 in the joining direction X is preferably 1 mm or more and 10 mm or less, and more preferably 6 mm or more and 8 mm or less.

[0036] From the same viewpoint as above, the fire-resistant foam material 29 is preferably located in the fire-resistant covering layer 26 at the joint portion 27. In this case, the fire-resistant foam material 29 is provided preferably within 60 mm, more preferably within 40 mm, from the surface of the covering material 20 in the thickness direction Y of the covering material 20. The fire-resistant foam material 29 is also provided preferably at a distance of 20 mm or more, more preferably 15 mm or more, from the surface of the covering material 20 in the thickness direction Y of the covering material 20.

[0037] As shown in Figure 4, the seam 27 in the rear-side facing portion 28b preferably has a gap G1 between the protruding portion of the second-part seam 23 and the corresponding recess of the first-part seam 22. This makes it easy to eliminate dimensional errors. The gap G1 is preferably between 1 mm and 3 mm.

[0038] The joint structure between the part covering materials 21 is not particularly limited, and may be a known joint such as a two-piece joint, a dovetail joint, a tenon joint, a half-tongue joint, etc. The shape of the part covering material 21 or the shapes of the part joints 22, 23 are set according to the type of joint. For example, the part covering material 21 shown in FIG. 1 has a substantially L-shaped cross section in a direction perpendicular to the axial direction of the part covering material 21. However, as shown in FIG. 5, the cross section of the part covering material 21 in the orthogonal direction may have a shape other than a substantially L-shape. The covering material 20B shown in FIG. 5 includes part covering materials 21a and 21b that cover the web portion of a beam B made of H-shaped steel, and a part covering material 21c that covers the bottom flange portion of the beam B. The part covering material 21a that covers the web portion has first part joints 22 on both sides that protrude along the axial direction of the beam B. This part covering material 21a has second part joints 23 and is joined to another part covering material 21b that covers the web portion. The part covering material 21c covering the lower flange portion has a step formed between the central protruding portion 26a protruding toward the beam B side and its surrounding area, and the part covering materials 21a and 21b covering the web portion are arranged in this step, and these part covering materials 21a, 21b, and 21c are joined together.

[0039] 1 is a horizontal joint of multiple part covering materials 21, but as shown in FIG. 6, multiple part covering materials 21 may also be vertically joined. The covering material 20C shown in FIG. 6 includes a part covering material 21d having at its upper end a second part joint 23a that protrudes in the axial direction of the steel member 10 that is the column A, and a short-side part covering material 21e and a long-side part covering material 21f having at their lower end a first part joint 22a that has a recess into which the second part joint 23a fits. The long-side part covering material 21f has a longer length in the circumferential direction of the steel member 10 than the short-side part covering material 21e. By fitting the second part joint 23a located at the upper end of the part covering material 21d with the first part joint 22a located at the lower end of the short side and long side part covering materials 21e, 21f, these part covering materials 21d, 21e, 21f are joined along the axial direction of the steel member 10.

[0040] The covering material 20 may cover the steel member 10 with a spacer disposed between the steel member 10 and the covering material 20. For example, if the steel member 10 is an H-beam, disposing a spacer on the web portion can facilitate the attachment of the part covering material 21 around the steel member 10. Wood plywood such as cedar can be used as the spacer. Furthermore, the spacer and the steel member 10 can be joined by known joining means such as an epoxy resin adhesive or staples.

[0041] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to such an embodiment and can be modified as appropriate. 2 has both the first part seam 22 and the second part seam 23, but the part covering material 21 may have either the first part seam 22 or the second part seam 23. For example, in a configuration in which the part covering material 21 has a generally L-shape in cross section in the orthogonal direction, the part covering material 21 may have the first part seam 22 at each end of one side a extending away from the right-angled corner and at each end of the other side b extending away from the right-angled corner, or may have the second part seam 23 at each end of these sides a and b. In this case, the part covering material 21 having the first part seam 22 at each end of both sides a and b is joined to the part covering material 21 having the second part seam 23 at each end of both sides a and b.

[0042] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples. [Example]

[0043] Example 1 A fire-resistant structural material having a configuration similar to that of the fire-resistant structural material 1 shown in FIG. 1 was manufactured by covering a steel member 10 with a covering material 20. A 2.5 mm-thick spacer was placed between the steel member 10 and the part covering material 21 on each of the four axially aligned sides of the steel member 10. Four part covering materials 211-214 having a generally L-shaped cross section were then placed, and joints 28 were fastened with screws 24 to secure adjacent part covering materials 211-214 to each other in the circumferential direction of the steel member 10. The length of the screws 24 in the joint direction X was 12 mm. In Example 1, a plurality of screws 24 were arranged intermittently along the vertical direction Z in the joints 28, starting from a position 75 mm below the top end of the covering material 20, and the spacing between the screws 24 in the Z direction was 150 mm. As shown in Fig. 4, a fire-resistant foam material 29 was placed at the joint 27 of the front surface-side opposing portion 28a. The fire-resistant foam material 29 was placed at the joint 27 over the entire axial length of the part covering material 21. At the locations corresponding to the part covering materials 211 and 214, the steel members 10 and the spacer were joined with an epoxy resin adhesive. At the locations corresponding to the part covering materials 212 and 213, the steel members 10 and the spacer were joined with staples.

[0044] The steel member 10 used was a square steel pipe with a cross-sectional (transverse) dimension of 350 mm x 350 mm in the orthogonal direction. The part covering material 21 used had a burnable covering layer 25 with a thickness of 15 mm and a fire-resistant covering layer 26 with a thickness of 85 mm. The burnable covering layer 25 was made of cedar board (density: 0.33 g / cm 3 , moisture content: 11%), and the fire-resistant coating layer 26 is made of larch (density: 0.45 g / cm 3 The building was made of laminated wood with a moisture content of 13.1%, and the burn-off coating layer 25 and the fire-resistant coating layer 26 were bonded together with a resorcinol-based resin adhesive. The square steel pipes used were STKR490 as specified in JIS G 3466. Cedar plywood was used as the spacers. As the fire-resistant foam material 29, a foamable fire-resistant sheet material was used. The obtained fire-resistant structural material had a cross-sectional dimension of 555 mm x 555 mm, an axial length of 3300 mm, and the length of the covering material 20 in the axial direction was 3000 mm.

[0045] (Comparative Example 1) A fire-resistant structural material was produced in the same manner as in Example 1, except that the covering material shown in FIG. 7 was used. The covering material of Comparative Example 1 did not include the fire-resistant foam material 29, and was fastened at the joint 28 with a pair of screws 24 aligned in the joint direction X. In this Comparative Example 1, at the joint 28, a plurality of screws 24 were aligned in two rows, spaced apart 75 mm below the top end of the covering material 20, along the vertical direction Z, with the spacing between the screws 24 in the direction Z being 150 mm. The steel member 10 and the spacer were joined with an epoxy resin adhesive.

[0046] (evaluation) (Combustion Test I) The fire-resistant structural materials of Example 1 and Comparative Example 1 were placed upright in a test furnace, and each of the four sides of the steel member 10 was heated for one hour using the ISO834 standard heating method, which simulates a normal fire.After heating was completed, Example 1 was allowed to cool in the furnace for eight hours, and Comparative Example 1 for nine hours. At that time, the temperature change was measured at each position shown in Figures 8(a) to (c), and the temperature change over time at each position was recorded. Hereinafter, each position indicated by a black dot in Figures 8(b) and (c) will be referred to using the numbers shown in Figure 8, such as Position 1, Position 2, etc. The shapes of the joints of the parts differ slightly between Example 1 and Comparative Example 1, but Positions 13 to 16 and Positions 29 to 32 in Comparative Example 1 were positioned 50 mm away from the recesses of the joints of the parts. The results of measuring the temperature change at each position are shown in Figure 9 for Example 1 and Figure 10 for Comparative Example 1. Furthermore, the state of the heating surface was visually confirmed for Example 1 and Comparative Example 1. The state of the fire-resistant structural materials of Example 1 and Comparative Example 1 after the combustion test is shown in Fig. 11 and Fig. 12, respectively.

[0047] For the fire-resistant structural material of Example 1, the cedar boards on the surface continued to burn after heating was completed, but as the flames died down, the temperature inside the furnace was observed to drop (not shown). Furthermore, for the burn-resistant coating layer 25, the red heat on the surface subsided about 45 minutes after the flaming combustion and then cooled down, and the red heat almost completely stopped after about 2 hours. In Example 1, as shown in Figure 11, no red heat was observed at the seam portion 27, and as shown in Figure 9(c), at positions 13 to 16 located near the seam portion 27, after the temperature dropped, the temperature did not rise again until the end of the test. Furthermore, as shown in FIG. 12, in Example 1, the burned charcoal and the like did not reach the rear surface side at the joint portion 27 of the fire-resistant coating layer 26 after the combustion test.

[0048] On the other hand, in Comparative Example 1, red heat was observed at the seam 27, and this red heat continued even after about 7 hours of cooling. In Figure 11, the red heat at the seam 27 is shown by a white circle. The temperature rise at position 5 indicated by the arrow in Figure 10(a) is thought to be due to the red heat. Furthermore, as shown by the arrow in Figure 10(c), at position 16 located near the seam 27, the temperature dropped and then rose again. This is thought to be due to the red heat at the seam 27. As shown in FIG. 12, in Comparative Example 1, the joint portion of the fire-resistant coating layer 26 after the combustion test was burned all the way to the back side. Therefore, it is understood that the covering material 20 of Example 1 was able to suppress red heat in the fire-resistant structural material.

[0049] Examples 2 to 7 As shown in FIG. 13, a covering material was prepared by joining two part covering materials at a joint 28. The part covering material 21 used had a burn-off covering layer 25 with a thickness of 15 mm and a fire-resistant covering layer 26 with a thickness of 85 mm. This part covering material was made of cedar (density: 0.33 g / cm3) as the burn-off covering layer 25. 3 , moisture content: 9%), and the fire-resistant coating layer 26 is made of larch (density: 0.44 g / cm 3The two part covering materials were constructed of laminated wood with a moisture content of 11%, and the burn-off covering layer 25 and the fire-resistant covering layer 26 were joined with a resorcinol-based resin adhesive. The two part covering materials were fastened together at a joint 28 with screws 24. In Examples 2 to 7, the joint 28 had a plurality of screws 24 intermittently arranged in a line along the vertical direction Z, starting from a position 75 mm below the top end of the covering material 20, with the spacing between the screws 24 in the same direction Z being 150 mm. The lowest screw 24 in the joint 28 was driven into a position 75 mm above the bottom end of the covering material 20. The screws 24 were the same as those in Example 1. The fire-resistant foam material 29 was the same as that in Example 1, and was disposed in the front-side facing portion 28a. At this time, the fireproof foam material 29 was arranged over the entire axial length of the part covering material 21 in the front surface side facing portion 28a. 13(a) to 13(f), the covering materials of Examples 2 to 7 were each varied in the length of the front-side facing portion 28a in the thickness direction Y of the covering material, or in the position of the fireproof foam material 29 in the front-side facing portion 28a. Specifically, for each covering material 20 of Examples 2 to 7, the thickness a1 of the front-side facing portion 28a, the thickness a2 of the back-side facing portion 28b, the distance a3 of the fireproof foam material 29 from the surface of the covering material, and the length a4 of the fireproof foam material 29 in the thickness direction of the covering material were varied as shown in Table 1 below. These lengths a1, a2, a3, and a4 are shown in FIG. 14.

[0050] [Table 1]

[0051] (evaluation) (Combustion Test II) The coating materials 20 of Examples 2 to 7 were placed upright in a test furnace, and the surface on the side of the burnable coating layer 25 was heated for one hour using the ISO834 standard heating method, which simulates a normal fire.After heating was completed, the materials were allowed to cool in the furnace for six hours. At that time, the temperature change was measured at each position shown in Figures 15(a) and (b), and the temperature change over time at each position was recorded. Hereinafter, each position indicated by a black dot in Figure 15(b) will be referred to as position 1, position 2, etc. using the numbers shown in Figure 15. The results of measuring the temperature change at each position are shown in Figures 16 and 17, respectively. The state of the upper surface was also visually confirmed for Examples 2 to 7. The state of each of the coating materials for Examples 2 to 7 after the combustion test is shown in FIG.

[0052] As shown in Figures 16 and 17 (a) to (f), no significant temperature increase was observed at positions 2, 10 or 6, 14 or positions further back, i.e., at the back-side facing portion 28b, and after the temperature dropped, it did not increase again until the end of the test. As shown in FIGS. 18(a) to (f), although the burnable coating layer 25 was burned, the burned state did not reach the rear surface facing portion 28b. Therefore, it is understood that the coating materials 20 of Examples 2 to 7 exhibited good flame-extinguishing performance. [Explanation of symbols]

[0053] 1 Fireproof structural materials 10 Steel parts 20 Covering material 21 Parts coating material 22 First part joint 23 Second part joint 24 Fasteners 24a Filler Dowel Material 25 Burnable coating layer 26 Fire-resistant coating layer 27 Seam 28 Joint 28a Front facing part 28b Back side facing part 29 Fireproof foam Y: thickness direction of coating material Z vertical direction

Claims

1. A coating material for coating a steel member, The covering material is formed by a plurality of part covering materials, each of the part covering materials has a laminated structure including a burnable covering layer that forms the surface of the covering material and is made of pure wood, and a fire-resistant covering layer that is located between the steel member and the burnable covering layer and is made of pure wood; The part covering materials can be joined together to cover the surface of the steel member, The part covering is provided with a fire-resistant foam material that seals the seam portion of the joint.

2. The covering of claim 1 , wherein the seam is located other than at a corner of the covering.

3. The covering material according to claim 1 or 2, wherein a fastener penetrating the laminated structure is provided at a joint between a plurality of the part covering materials.

4. The covering material according to claim 1 or 2, wherein the joint portion is bent in a crank shape in a cross section of the covering material in a thickness direction.

5. The covering material according to claim 1 or 2, wherein the part covering material has a substantially L-shape in a cross section taken along a direction perpendicular to an axial direction of the part covering material.

6. the joints of the plurality of part covering materials each have a front-side opposing portion that faces each other on the front side of the covering material and a back-side opposing portion that faces each other on the back side of the front-side opposing portion, and the positions of the front-side opposing portion and the back-side opposing portion are offset in the joint direction; The covering material according to claim 1 or 2, wherein the fire-resistant foam material is provided so as to be located at the surface-side facing portion.

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