JP7649710B2 - Fireproofing of synthetic materials - Google Patents

Description

The present invention relates to fire-resistant structures of composite members, including wood-steel hybrid members made of wood and steel.

Previously, the applicant for this patent has developed a wood-steel hybrid beam (hereinafter referred to as a wood-steel beam), a structural member with a fire resistance of one hour, in which a steel beam is fire-resistantly covered with wood (hereinafter referred to as a wood covering material) (see, for example, Patent Document 1). This wood covering material burns at 0.7 to 1.0 mm/min during a fire, but stops burning after the fire, thereby suppressing the temperature rise of the steel beam that supports the load and preventing collapse.

When wood-steel beams are used in buildings, there may be places where the wood covering material and other fire-resistant covering materials come into contact with each other. For example, on the periphery of a steel-framed structure, through holes are provided in the steel beams to allow piping to pass through. From the standpoint of ease of construction, cost reduction, and appearance, it may be possible to provide a fire-resistant covering for the through holes and their surroundings with a fire-resistant covering material other than the wood covering material (for example, fire-resistant paint or sprayed rock wool).

When the type of fire-resistant coating material changes in the axial direction of the beam as described above, several techniques are known to ensure fire resistance at the boundary between different types of fire-resistant coating materials. (See Patent Documents 2 and 3 for examples.)

Patent application No. 2020-148315 (currently unpublished) JP 2020-143528 A JP 2020-172808 A

However, when the above-mentioned wood-steel beams are applied to buildings, there is a risk that the specified fire resistance performance cannot be achieved at the places where the wood coating material and other non-wood-based fire-resistant coating materials meet. When covering steel members with fire-resistant coating materials such as fire-resistant paint or sprayed rock wool, the thickness and specifications of the fire-resistant coating material are determined so that the steel temperature is 350°C or less on average and 450°C or less at most. On the other hand, the ignition temperature of wood is about 200 to 260°C. Therefore, at the places where the wood coating material meets other fire-resistant coating materials, the heat is transferred from the steel member covered with the other non-wood-based fire-resistant coating material to the steel member covered with the wood coating material, and the steel temperature of the steel member on the wood coating material side may reach 200 to 260°C. If this happens, the wood coating material may burn from the inside and not stop burning, causing the steel temperature of the steel member to reach 450°C or more. Furthermore, at the joints between wood covering materials and other non-wood based fire-resistant covering materials, the end faces of the wood covering materials may be exposed, or gaps may appear between the wood covering materials and other non-wood based fire-resistant covering materials, which may result in the specified fire resistance not being ensured.

The present invention has been made in consideration of the above, and aims to provide a fire-resistant structure made of composite members that can ensure the fire resistance of the joint between a wood covering material and another non-wood-based fire-resistant covering material.

In order to solve the above problems, the fireproof structure of the composite member of the present invention is a fireproof structure of the joint between the first and second regions of a composite member comprising a steel member, a thick wood covering material covering a first region of the surface of the steel member, and a thin non-wood-based fireproof covering material covering a second region of the surface of the steel member adjacent to the first region, characterized in that it has a non-wood-based fireproof covering material that covers the surface of the steel member near the joint with a thickness equal to or greater than the thickness of the fireproof covering material of the second region, and an inorganic fireproof material that continuously covers the end surface of the wood covering material and the fireproof covering material of the joint.

The fire-resistant structure of another composite member according to the present invention is characterized in that, in the above-mentioned invention, the non-wood-based fire-resistant coating material is made into a fire-resistant paint and its thickness is increased.

In addition, in the above-mentioned invention, the inorganic fire-resistant material in the fire-resistant structure of another composite member according to the present invention is a reinforced gypsum board attached to the edge of the wood covering material, and an inorganic filler is provided in the gap between the reinforced gypsum board and the steel frame member.

The fire-resistant structure of the composite member according to the present invention is a fire-resistant structure of a joint between a first region and a second region in a composite member comprising a steel member, a thick wood covering material covering a first region of the surface of the steel member, and a thin non-wood-based fire-resistant covering material covering a second region of the surface of the steel member adjacent to the first region. The non-wood-based fire-resistant covering material covers the surface of the steel member near the joint with a thickness equal to or greater than the thickness of the fire-resistant covering material of the second region, and the inorganic fire-resistant material covers the end face of the wood covering material and the fire-resistant covering material of the joint continuously. This has the effect of ensuring the fire resistance of the joint between the wood covering material and another non-wood-based fire-resistant covering material.

In addition, according to the fire-resistant structure of another composite member of the present invention, by using a fire-resistant paint as a non-wood-based fire-resistant coating material and increasing its thickness, it is possible to ensure the fire resistance of the interface between the wood coating material and the fire-resistant paint.

In addition, according to another fire-resistant structure of composite members of the present invention, the inorganic fire-resistant material is a reinforced gypsum board attached to the edge of the wooden covering material, and an inorganic filler is provided in the gap between this reinforced gypsum board and the steel frame member, which has the effect of suppressing the inflow of heat and combustion from the edge and suppressing the rise in the steel temperature of the steel frame member on the wooden covering material side.

FIG. 1 is a side view showing an embodiment of a fire-resistant structure of a composite member according to the present invention. FIG. 2 is a cross-sectional view taken along line AA of FIG. FIG. 3 is a cross-sectional view taken along line BB of FIG. FIG. 4 is a cross-sectional view taken along line CC of FIG. FIG. 5(1) is a graph showing the average temperature change at each cross-sectional position, and (2) is a table showing the maximum temperature at each cross-sectional position.

Below, an embodiment of the fire-resistant structure of a composite member according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment.

As shown in Figures 1 to 4, the fire-resistant structure 10 of a composite member according to an embodiment of the present invention is a fire-resistant structure of a joint 20 between a first region R1 and a second region R2 in a composite member 18 that includes a steel beam 12 (steel member), a thick wood coating material 14 that covers a first region R1 on the surface of the steel beam 12, and a thin fire-resistant paint 16 (non-wood-based fire-resistant coating material) that covers a second region R2 on the surface of the steel beam 12 adjacent to the first region R1.

This fireproof structure 10 has a fireproof paint 22 that covers the surface of the steel beam 12 at the joint 20 with a coating thickness equal to or greater than the coating thickness of the fireproof paint 16 in the second region R2, and a reinforced gypsum board 26 (inorganic fireproof material) that continuously covers the end surface 24 of the wood covering material 14 and the fireproof paint 22 at the joint 20. In this embodiment, the fireproof paints 16 and 22 are applied to a predetermined length range (length range up to the fireproof covering material 42) in the second region R2 from the end surface 24 of the wood covering material 14 with the same thickness equal to or greater than the required coating thickness. On the lateral and downward outer parts of the end surface 24 of the wood covering material 14, a finishing wood 28 and a normal gypsum board 30 are laminated adjacent to the reinforced gypsum board 26. Instead of providing the finishing wood 28 and the normal gypsum board 30, the reinforced gypsum board may be attached to the entire end surface 24 of the wood covering material 14.

The steel beam 12 is made of an H-shaped steel extending in a substantially horizontal direction, and has a web 32, an upper flange 34, and a lower flange 36. The steel beam 12 in the first region R1 and the steel beam 12 in the second region R2 are butted together at the joint 20, and are joined to each other by a plate 38 and a bolt 40 provided on the web 32. The beam formed by the steel beam 12 in the first region R1 and the wood covering material 14 corresponds to a wood-steel beam. In the example shown in the figure, the steel beam 12 on the second region R2 side is provided with a fireproof covering material 42 made of a calcium silicate board and a through hole 44 for passing piping, but these can be omitted. The steel beams 12 in the first region R1 and the second region R2 do not have to be butted together by the bolts 40 and the plate 38. For example, the steel beams 12 in the first region R1 and the second region R2 may be continuous in the beam axis direction.

The wooden covering material 14 is made of laminated wood that is provided to cover the top, bottom, left and right sides of the steel beam 12, and is formed of a tree species such as Japanese cypress or larch that has a fire resistance of one hour. The wooden covering material 14 is fixed to the web 32 of the steel beam 12 with a fixing member 46 such as a lag screw. As shown in FIG. 4, this fixing member 46 is a metal rod-shaped body having a plate-shaped head 48 and a shaft-shaped screw portion 50. The screw portion 50 has a sharp tip and a screw thread on its outer periphery. The fixing member 46 is screwed into the wooden covering material 14 through through holes 52 provided on the upper and lower sides of the web 32 in the same cross section. The through holes 52 are blocked with filler wood 54. As shown in FIG. 1, the fixing members 46 are arranged at a predetermined interval in the horizontal direction in which the steel beam 12 extends, and are arranged so that the screwing directions are staggered horizontally.

The fire-resistant paints 16 and 22 are made of a foaming fire-resistant material that foams at a predetermined temperature range when heated to suppress the temperature rise of the steel material. For example, there is a fire-resistant paint that starts foaming at about 250°C when heated during a fire and foams 20 to 30 times to form an insulating layer. In this embodiment, the coating thickness of the fire-resistant paint 16 in the second region R2 and the coating thickness of the fire-resistant paint 22 in the joint portion 20 are both set to a coating thickness that satisfies the two-hour fire resistance performance, but the present invention is not limited to this. In this embodiment, the fire-resistant paints 16 and 22 are provided in a length range from the end surface 24 of the wood coating material 14 to the fire-resistant coating material 42, and have a coating thickness that satisfies the two-hour fire resistance performance, but the present invention is not limited to this. For example, fire-resistant paint 16, 22 with a coating thickness that satisfies two-hour fire resistance may be applied to the length range extending beyond the above range from the end surface 24 of the wood coating material 14, and fire-resistant paint with a coating thickness that satisfies one-hour fire resistance may be applied to the range beyond that.

The reinforced gypsum board 26 is a plate-like member that is attached to the end surface 24 of the wooden covering material 14. For construction purposes, a certain gap (clearance) is required between the reinforced gypsum board 26 and the steel beam 12. To prevent heat from entering through this gap, an inorganic filler 56 (e.g., calcium carbonate-based filler) is placed in the gap.

As described above, in this embodiment, in the area where the wooden coating material 14 of the wooden steel beam and the fire-resistant paint 16 (non-wood-based fire-resistant coating material) meet, the coating thickness of the fire-resistant paint is increased to meet the one-hour fire resistance performance, and reinforced gypsum board 26 (inorganic fire-resistant material) is provided at the interface 20 between the wooden coating material 14 and the fire-resistant paint 22. According to this embodiment, the following effects are obtained.

(1) By changing the coating thickness of the fire-resistant paint from a 1-hour fire-resistant specification to a 2-hour fire-resistant specification, the increase in the temperature of the steel on the fire-resistant paint 16 side (second region R2) is reduced, and the increase in the temperature of the steel due to heat transfer to the steel beam 12 on the wood coating material 14 side (first region R1) is suppressed.
(2) By attaching the reinforced gypsum board 26 to the end surface 24 of the wooden covering material 14, the inflow of heat from the end surface 24 is suppressed. Also, the end surface 24 of the wooden covering material 14 is prevented from being directly exposed to flames and burning.
(3) By providing a reinforced gypsum board 26 between the wood covering material 14 and the fire-resistant paint 16, the reinforced gypsum board 26 absorbs the heat of the steel beam 12 on the fire-resistant paint 16 side, thereby suppressing the rise in the temperature of the steel on the wood covering material 14 side.

<Example>
Next, an embodiment of the present invention will be described. The following is a specification for verifying fire resistance performance in a one-hour fire resistance test. The specifications of the joint between the wood-steel beam and the fire-resistant paint verified in the fire resistance test are as shown in Figures 1 to 4. The dimensions and steel type of the steel beam used for the test specimen are BH-900 x 150 x 16 x 19, total length 3450 mm (SS400). The wood coating material is hiba laminated lumber (symmetrical different grade E95-F270), coating material thickness 80 mm, and the cross-sectional dimensions of the wood-steel beam are 1067 mm x 317 mm. In the fire resistance test, a case where a through hole is provided in the steel beam is assumed.

(Fireproof paint film thickness)
Generally, if the structure is fire-resistant for one hour, a fire-resistant paint with a coating thickness specified for one-hour fire resistance should be applied. However, for fire-resistant paint that is used in contact with wooden steel beams, a fire-resistant paint with a coating thickness that can achieve two-hour fire resistance was applied to reduce the rise in the temperature of the steel material on the fire-resistant paint side and to suppress the rise in the temperature of the steel material due to heat transfer to the steel beam on the wooden covering material side. This fire-resistant paint was applied within a length range of 650 mm from the small end of the wooden covering material.

(Installation of reinforced gypsum board)
A number of reinforced gypsum boards were provided on the edge of the wooden covering material. In the fire resistance test, reinforced gypsum boards (21 mm thick x 3 sheets) and reinforced gypsum boards (12.5 mm thick) were laminated together to a total thickness of 75.5 mm. It is considered that increasing the thickness of the reinforced gypsum boards improves the insulation performance and increases the heat absorption capacity of the reinforced gypsum boards, thereby improving the fire resistance performance. Therefore, if the total thickness of the reinforced gypsum boards provided on the edge of the wooden covering material is 75.5 mm or more, it is considered that the fire resistance performance is guaranteed even if the number and thickness of the reinforced gypsum boards are changed.

(Filling the gap)
In construction, a clearance is required between the reinforced gypsum board attached to the edge of the wooden covering material and the steel beam. To prevent heat from entering through this gap, an inorganic filler (such as a calcium carbonate filler) is injected to fill the gap.

In addition, for the fire resistance tests, test specimens were manufactured so that the clearance between the reinforced gypsum board and the steel beams was 3 mm. However, by reducing the clearance between the reinforced gypsum board and the steel beams, it is believed that the reinforced gypsum board can more easily absorb the heat from the steel beams, and that the inflow of heat through the gaps can be minimized. Therefore, it is believed that fire resistance can be guaranteed if the clearance between the reinforced gypsum board and the steel beams is 3 mm or less.

(Installation of finishing wood)
To improve the appearance, a finishing wood (Japanese cypress laminate, 55 mm thick) and a normal gypsum board (12.5 mm thick) were laminated on the outer periphery of the end surface of the wooden covering material. Also, if finishing wood is not attached, it is believed that fire resistance can be guaranteed by attaching reinforced gypsum board to the entire end surface of the wooden covering material.

(Fire resistance test results)
Next, the results of a one-hour fire resistance test at the joint using the above test specimen will be explained. The fire resistance test was completed by heating the test specimen for one hour, then cooling it in the furnace for 48 hours. At the end of the test, no red heat or smoke was observed, and the wood covering material had stopped burning. In addition, the finishing wood (55 mm thick) and the ordinary finishing gypsum board (12.5 mm thick) had fallen off, but the reinforced gypsum board (21 mm thick x 3 sheets + 12.5 mm thick) on the small end surface remained.

Figure 5 (1) shows the time progression of the average temperature at each cross-sectional position measured by thermocouples installed on the upper and lower flanges and web. The legend in the figure indicates the horizontal distance from the end face of the wood coating material. Figure 5 (2) shows the maximum temperature at each cross-sectional position. As shown in Figure 5 (2), the maximum steel temperature of the steel beam coated with fire-resistant paint was 341.5°C, and the maximum steel temperature of the steel beam coated with wood coating material was 202.0°C, both of which are below the allowable temperature of 350°C for steel in fire resistance tests. Therefore, it can be said that the specifications of this embodiment have a fire resistance performance of 1 hour.

According to this embodiment, by using reinforced gypsum board at the joint between the wood covering material and the fire-resistant paint, it is possible to realize specifications that are easy to process and install on-site. In addition, by using fire-resistant paint and making specifications that assume the installation of finishing wood, it is possible to take into consideration the appearance of the finished product.

In the above embodiment, a fire-resistant paint is used for a non-wood-based fire-resistant coating material that competes with a wood-based coating material, but the present invention is not limited to this. If the specifications of the non-wood-based fire-resistant coating material are such that the steel temperature is 340°C or less in a one-hour fire resistance test, a non-wood-based fire-resistant coating material other than a fire-resistant paint (such as sprayed rock wool or wet ceramic fire-resistant coating material) may be used.

As explained above, the fire-resistant structure of the composite member according to the present invention is a fire-resistant structure of the joint between the first and second regions of a composite member that includes a steel member, a thick wood coating material that covers a first region of the surface of the steel member, and a thin non-wood-based fire-resistant coating material that covers a second region of the surface of the steel member adjacent to the first region. The non-wood-based fire-resistant coating material covers the surface of the steel member near the joint with a thickness equal to or greater than the thickness of the fire-resistant coating material of the second region, and the inorganic fire-resistant material continuously covers the end surface of the wood coating material and the fire-resistant coating material of the joint, so that the fire resistance of the joint between the wood coating material and another non-wood-based fire-resistant coating material can be ensured.

In addition, according to the fire-resistant structure of another composite member of the present invention, the non-wood-based fire-resistant coating material is made into a fire-resistant paint, and by increasing its thickness, the fire-resistant performance of the interface between the wood coating material and the fire-resistant paint can be ensured.

In addition, according to another fire-resistant structure of a composite member of the present invention, the inorganic fire-resistant material is a reinforced gypsum board attached to the edge of the wooden covering material, and an inorganic filler is provided in the gap between this reinforced gypsum board and the steel frame member, which suppresses the inflow of heat and combustion from the edge and also suppresses the temperature rise of the steel frame member on the wooden covering material side.

As described above, the fire-resistant structure of the composite member according to the present invention is useful for a composite member having a steel member and a wood-based covering material, and is particularly suitable for ensuring the fire resistance of the joint between the wood-based covering material and other non-wood-based fire-resistant covering materials.

10 Fireproof structure of composite members 12 Steel beam (steel member)
14 Wood coating material 16, 22 Fireproof paint (non-wood-based fireproof coating material)
18 Composite member 20 Joint portion 24 End surface 26 Reinforced gypsum board (inorganic fireproof material)
28 Finishing wood 30 Ordinary gypsum board 32 Web 34 Upper flange 36 Lower flange 38 Plate 40 Bolt 42 Fireproof covering material 44 Through hole 46 Fixing member 48 Head 50 Threaded portion 52 Through hole 54 Filler wood 56 Filler material R1 First region R2 Second region

Claims (3)

A fireproof structure of a joint between a first area and a second area of a composite member comprising a steel member, a thick wood covering material covering a first area of the surface of the steel member, and a thin non-wood based fireproof covering material covering a second area of the surface of the steel member adjacent to the first area,
A non-wood-based fire-resistant coating material that covers the surface of the steel member near the joint with a thickness equal to or greater than the thickness of the fire-resistant coating material in the second region;
A fireproof structure of a composite member, characterized in that it has an inorganic fireproof material that continuously covers the end surface of a wood covering material and the fireproof covering material at the joint. The fire-resistant structure of composite members described in claim 1, characterized in that the non-wood-based fire-resistant coating material is made into a fire-resistant paint and its thickness is increased. The fireproof structure of composite members described in claim 1 or 2, characterized in that the inorganic fireproof material is a reinforced gypsum board attached to the edge of the wood covering material, and an inorganic filler is provided in the gap between the reinforced gypsum board and the steel frame member.

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