Fire-resistant structure and construction method for fire-resistant structure

Abstract

To provide a fire-resistant structure and the like that can prevent a decrease in fire resistance due to thermal bridges and an interference between a fire-resistant coating and a rib of a flat deck in a fire-resistant structure of a wooden beam in a floor structure using the wooden beam and a flat deck.SOLUTION: The fire-resistant structure of the present invention is a fire-resistant structure in which a flat deck 2 is provided between wooden beams, a slab 3 is constructed on the flat deck 2 and a wooden beam 1, and a fire-resistant coating 4 is provided to cover the outer surface of the wooden beam 1. There is a gap between an upper edge 1e of a side surface 1S of the wooden beam 1 and an edge 2E of the flat deck 2 in the direction along the horizontal plane.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fire-resistant structure in which a steel deck plate for floor formwork (hereinafter referred to as a "flat deck") is used, a slab is constructed on the flat deck and wooden beams, and a fire-resistant coating is provided on the outer surface of the wooden beams, and a construction method for the fire-resistant structure. [Background technology]

[0002] BACKGROUND ART A formwork construction method is known in which a floor structure is constructed by combining wooden beams and a slab by assembling a formwork between wooden beams and pouring concrete onto the formwork and the wooden beams. However, this formwork method requires a lot of work, such as the installation of supports and the installation and dismantling of formwork. Therefore, in order to save labor and shorten the construction period, a construction method using a flat deck is known. The flat deck is a steel deck plate configured to function as a formwork, and is configured to have a flat plate portion and ribs protruding downward from the underside of the flat plate portion (see Patent Document 1). When using the flat deck to construct a floor structure that combines wooden beams and a slab, for example, as shown in Figure 3(a), the flat deck 2 is placed between one wooden beam 1 and another wooden beam 1 not shown in the figure, and concrete C is poured on the flat deck 2 and wooden beam 1 to construct the slab 3. The flat deck 2 comprises a flat plate portion 20 that is long in one direction and has a plurality of ribs 21 that protrude downward from the underside 2a of the flat plate portion 20 and extend in the longitudinal direction of the flat plate portion 20, and both end sides of the ribs 21 have inclined edges 21S that are formed to rise at an angle toward the longitudinal edge 2E of the flat plate portion 20, and the longitudinal end of the flat plate portion 20 between the upper end 21t of the inclined edge 21S of the rib 21 and the longitudinal edge 2E of the flat plate portion 20 is configured so that no ribs 21 are present. Therefore, the underside 2a of the edge 2E at the longitudinal end of the flat plate portion 20 is placed on the upper surface 1T of the wooden beam 1, and the underside 2a of the middle part of the longitudinal direction of the flat plate portion 20 is supported with a support material not shown in the figure, and then concrete C is poured on the flat deck 2 and wooden beam 1, thereby constructing a slab 3 on the flat deck 2 and wooden beam 1. Although not shown in the figure, fixing members such as studs are provided on the upper surface of the wooden beam 1 and the upper surface of the flat plate portion 20 of the flat deck 2 to secure the concrete C, and reinforcing bars of the slab 3 are arranged above the wooden beam 1 and the flat deck 2. Then, as shown in FIG. 3(b), a fire-resistant coating 4 is provided to cover the outer surfaces of the wooden beam 1 (side surfaces 1S, 1S and bottom surface 1B of the wooden beam 1). The fire-resistant cladding 4 is made up of one or more layers of gypsum boards 40 attached to one another. As a result of the above, concrete C is poured onto the flat deck 2 and the wooden beams 1 to construct the slab 31, and a fire-resistant structure is obtained in which the fire-resistant coating 4 is provided to cover the outer surfaces of the wooden beams 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-110485 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional fire-resistant structure shown in Figure 3, the underside 2a of the edge 2E at the longitudinal end of the flat plate portion 20 of the flat deck 2 is placed on the upper surface 1T of the wooden beam 1, which causes the following problems. (1) In the event of a fire, the flat deck 2 could act as a thermal bridge, transferring heat to the wooden beam 1. In other words, there was a problem of reduced fire resistance due to thermal bridging. (2) The gap wb between the upper end 21t of the inclined edge 21S at the end of the rib 21 of the flat deck 2 and the side surface 1S of the wooden beam 1 becomes narrow, which may cause interference between the upper end of the gypsum board 40 attached to the side surface 1S of the wooden beam 1 and the inclined edge at the end of the rib 21. If this interference occurs, the gypsum board must be cut out. In this case, as shown in Figure 3(b), a gap S is created between the cut surface 40t of the cutout portion and the inclined edge 21S at the end of the rib 21, which may result in the fire-resistant coating 4 not meeting the required thickness for fire resistance, potentially resulting in a fire-resistant structure that does not achieve the desired fire resistance. That is, there was a problem of deterioration in fire resistance due to interference between the fire-resistant coating 4 and the rib 21 of the flat deck 2. The present invention has been made in consideration of the above-mentioned problems, and provides a fire-resistant structure that can prevent a decrease in fire resistance performance due to thermal bridging and a decrease in fire resistance performance due to interference between the fire-resistant coating and the ribs of the flat deck in a fire-resistant structure of a wooden beam in a floor structure using wooden beams and a flat deck, and a construction method for the fire-resistant structure. [Means for solving the problem]

[0005] The fire-resistant structure of the present invention is a fire-resistant structure in which a steel deck plate for floor formwork is provided between wooden beams, a slab is constructed on the steel deck plate for floor formwork and the wooden beams, and a fire-resistant coating is provided to cover the outer surface of the wooden beams, and is characterized in that there is a gap between the upper edge of the side of the wooden beam and the edge of the steel deck plate for floor formwork in the direction along the horizontal plane. The fire-resistant structure of the present invention makes it possible to provide a fire-resistant structure that can prevent a decrease in fire resistance due to thermal bridges and a decrease in fire resistance due to interference between the fire-resistant coating and the ribs of the flat deck. The fire-resistant structure construction method of the present invention is a fire-resistant structure construction method as described above, characterized in that it comprises the steps of fixing a support material on which the edge side of the steel deck plate for the floor formwork is placed to the upper edge side of the side of the wooden beam, placing the edge side of the steel deck plate for the floor formwork on the support material so that the upper edge side of the side of the wooden beam is spaced apart from the edge of the steel deck plate for the floor formwork in a direction along the horizontal plane, pouring concrete on top of the wooden beam, support material, and steel deck plate for the floor formwork to construct a slab, and after constructing the slab, removing the support material and forming a fire-resistant coating that covers the side and underside of the wooden beam. The fire-resistant structure construction method of the present invention is a fire-resistant structure construction method described above, characterized in that it includes the steps of fixing to the top surface of the wooden beam a non-combustible plate material that covers the top surface of the wooden beam and has an end face that is positioned outward from the upper edges of the left and right side surfaces of the wooden beam; placing the end edge side of the steel deck plate for the floor formwork on the non-combustible plate material so that the upper edge side of the wooden beam is spaced apart from the end edge of the steel deck plate for the floor formwork in a direction along the horizontal plane; pouring concrete on the non-combustible plate material and the steel deck plate for the floor formwork to construct a slab; and forming a fire-resistant coating that covers the side and underside of the wooden beam. According to the method for constructing a fire-resistant structure of the present invention, the fire-resistant structure of the present invention can be constructed easily and reliably. [Brief explanation of the drawings]

[0006] [Figure 1] 1A and 1B are diagrams showing a construction method and a fire-resistant structure of a fire-resistant structure according to embodiment 1, in which (a) shows a state in which a slab is constructed on a flat deck and wooden beams, and (b) shows a fire-resistant structure in which a fire-resistant coating is formed to cover the sides and undersides of the wooden beams. [Figure 2] 10A and 10B are diagrams showing a construction method and a fire-resistant structure of a fire-resistant structure according to a second embodiment, in which (a) shows a state in which a slab is constructed on a flat deck and wooden beams, and (b) shows a fire-resistant structure in which a fire-resistant coating is formed to cover the sides and undersides of the wooden beams. [Figure 3]The figures show an example of a conventional fire-resistant construction method and a fire-resistant construction, where (a) shows a slab constructed on a flat deck and wooden beams, and (b) shows a fire-resistant construction in which a fire-resistant coating is formed to cover the sides and underside of the wooden beams. DETAILED DESCRIPTION OF THE INVENTION

[0007] Embodiment 1 A fire-resistant structure according to a first embodiment of the present invention will be described with reference to FIGS. As shown in Figures 1 and 2, the fire-resistant structure of embodiment 1 has a flat deck 2 provided between one wooden beam 1 and another wooden beam 1 not shown, a slab 3 constructed on the flat deck 2 and the wooden beam 1, and a fire-resistant coating 4 provided on the outer surface of the wooden beam 1, and is configured so that the upper edge 1e of the side surface 1S of the wooden beam 1 and the edge 2E of the flat deck 2 are separated by a predetermined distance a in the direction along the horizontal plane.

[0008] As described above, the flat deck 2 is a steel deck plate configured to function as a formwork, and comprises a long, plate-shaped flat portion 20 that is long in one direction, and a plurality of ribs 21 that protrude downward from the underside 2a of the flat portion 20 and extend in the longitudinal direction of the flat portion 20, with both end sides of the ribs 21 having inclined edges 21S that are configured to rise at an angle toward the longitudinal edge 2E of the flat portion 20, and the longitudinal end of the flat portion 20 between the upper end 21t of the inclined edge 21S of the rib 21 and the longitudinal edge 2E of the flat portion 20 is configured so that no ribs 21 are present.

[0009] Next, a construction method for the fire-resistant structure according to the first embodiment will be described. As shown in Figure 1, the construction method of embodiment 1 includes the following steps: a first step of fixing the support material 5, on which the edge 2E side of the flat deck 2 is placed, to the upper edge 1e side of the side 1S of the wooden beam 1; a second step of placing the edge 2E side of the flat deck 2 on the support material 5 so that the upper edge 1e side of the side 1S of the wooden beam 1 and the edge 2E of the flat deck 2 are spaced apart in the direction along the horizontal plane; a third step of pouring concrete C on the wooden beam 1, support material 5, and flat deck 2 to construct a slab 3; and a fourth step of removing the support material 5 after constructing the slab 3 and forming a fire-resistant coating 4 to cover the side 1S and underside 1B of the wooden beam 1.

[0010] In the first step, for example, as shown in FIG. 1(a), a long material with an L-shaped cross section that is long in the extension direction of the wooden beam 1 (direction perpendicular to the paper surface of FIG. 1) is used as a receiving material 5. Then, the outer plate surface 5b of one of the L-shaped plate portions 5a of the receiving material 5 is brought into contact with the upper edge 1e of the side surface 1S of the wooden beam 1, and the outer plate surface 5d of the other L-shaped plate portion 5c of the receiving material 5 and the upper surface 1T of the wooden beam 1 are positioned on the same horizontal plane or approximately on the same horizontal plane, and one of the L-shaped plate portions 5a of the receiving material 5 is fixed to the side surface 1S of the wooden beam 1 using a screw 51 such as a screw.

[0011] In the second step, for example, as shown in Fig. 1(a), the lower surface 2a of the flat plate portion 20 on the edge 2E side of the flat deck 2 is placed on the outer plate surface 5d of the other L-shaped plate portion 5c of the receiving member 5. At this time, a predetermined distance a is set between the edge 2E of the flat deck 2 and the upper edge 1e of the side surface 1S of the wooden beam 1 in the direction along the horizontal plane.

[0012] In the third step, the underside 2a of the middle part of the longitudinal direction of the flat plate portion 20 of the flat deck 2 is supported with a support material not shown in the figure, and then concrete C is poured on top of the flat deck 2, supporting material 5 and wooden beams 1 to construct a slab 3 on top of the flat deck 2, supporting material 5 and wooden beams 1. Although not shown in the figure, fixing members such as studs are provided on the upper surface of the wooden beam 1 and the upper surface of the flat plate portion 20 of the flat deck 2 to secure the concrete C, and reinforcing bars of the slab 3 are arranged above the wooden beam 1 and the flat deck 2.

[0013] In the fourth step, after the slab 3 is constructed, the receiving material 5 is removed. Then, for example, gypsum board 40 is attached to cover the side surface 1S and the underside 1B of the wooden beam 1 to form the fire-resistant covering 4. In this case, the gypsum board 40 is attached with the upper edge surface of the gypsum board 40 in contact with the underside of the slab 3, or with the underside 2a of the flat plate portion 20 of the flat deck 2 on the edge 2E side.

[0014] According to the fire-resistant structure and construction method of the first embodiment, the upper edge 1e of the side surface 1S of the wooden beam 1 and the edge 2E of the flat deck 2 are spaced apart by a predetermined distance a in the direction along the horizontal plane. In other words, since the lower surface 2a on the edge 2E side at the longitudinal end of the flat portion 20 of the flat deck 2 is not in contact with the upper surface 1T of the wooden beam 1, the flat deck 2 can be prevented from becoming a thermal bridge. Therefore, in a fire-resistant structure in which a flat deck 2 is provided between wooden beams 1, a slab 3 is constructed on the flat deck 2 and wooden beams 1, and a fire-resistant coating 4 is provided on the outer surface of the wooden beams 1, it is possible to prevent a decrease in fire resistance performance due to thermal bridging. In addition, since the upper edge 1e of the side surface 1S of the wooden beam 1 and the edge 2E of the flat deck 2 are spaced apart by a predetermined distance a in the direction along the horizontal plane, the distance wa between the upper end 21t of the inclined edge 21S on the end side of the rib 21 and the side surface 1S of the wooden beam 1 is widened. Therefore, the upper end of the fire-resistant coating 4 provided on the side surface 1S of the wooden beam 1 and the inclined edge 21S on the end side of the rib 21 are less likely to interfere with each other, and it is no longer necessary to cut out, for example, the gypsum board 40 that forms the fire-resistant coating 4. This makes it possible to provide a fire-resistant structure that meets the required coating thickness for fire resistance performance and satisfies the desired fire resistance performance. In addition, since the gap wa between the upper end 21t of the inclined edge 21S on the end side of the rib 21 and the side surface 1S of the wooden beam 1 is wider, the thickness of the fire-resistant coating 4 can be made thicker, resulting in a fire-resistant structure with higher fire resistance performance.

[0015] Next, a construction method for a fire-resistant structure according to the second embodiment will be described. As shown in Figure 2, the construction method of embodiment 2 includes the following steps: a first step of fixing a non-combustible plate 6 to the upper surface 1T of the wooden beam 1, the non-combustible plate 6 being large enough to cover the upper surface 1T of the wooden beam 1 and having its edges 6E, 6E positioned outward from the upper edges 1e, 1e of the left and right side surfaces 1S, 1S of the wooden beam 1; a second step of placing the edge 2E side of the flat deck 2 on the non-combustible plate 6 so that the upper edge 1e side of the side surface 1S of the wooden beam 1 is spaced apart from the edge 2E of the flat deck 2 in the direction along the horizontal plane; a third step of pouring concrete C on the non-combustible plate 6 and the flat deck 2 to construct a slab 3; and a fourth step of forming a fire-resistant coating 4 that covers the sides 1S, 1S and the underside 1B of the wooden beam 1.

[0016] In the first step, for example, as shown in FIG. 2(a), a non-combustible plate material 6 having a predetermined thickness (for example, about 50 mm) is used as a receiving material. The non-combustible board 6 may be, for example, an ALC panel or a wood wool cement board. Then, the non-combustible board 6 is positioned so that it covers the upper surface 1T of the wooden beam 1 and its edges 6E, 6E are located outward from the upper edges 1e, 1e of the left and right side surfaces 1S, 1S of the wooden beam 1 (on the left and right sides of the wooden beam 1 in Figure 2), and then the non-combustible board 6 is fixed to the upper surface 1T of the wooden beam 1 using screws 61 or other screws that also function as fixing members for the concrete C.

[0017] In the second step, for example, as shown in Fig. 2(a), the lower surface 2a of the flat plate portion 20 on the edge 2E side of the flat deck 2 is placed on the upper surface 6a of the non-combustible plate material 6. At this time, a predetermined distance a is set between the upper edge 1e side of the side surface 1S of the wooden beam 1 and the edge 2E of the flat deck 2 in the direction along the horizontal plane.

[0018] In the third step, the underside 2a of the middle part of the longitudinal direction of the flat plate portion 20 of the flat deck 2 is supported with a support material not shown in the figure, and then concrete C is poured on top of the flat deck 2 and the non-combustible plate material 6 to construct a slab 3 on top of the flat deck 2 and wooden beams 1. Although not shown in the figure, fixing members such as studs are provided on the upper surface of the flat plate portion 20 of the flat deck 2 to secure it to the concrete C, and steel bars for the slab 3 are arranged above the wooden beams 1 and the flat deck 2.

[0019] In the fourth step, after constructing the slab 3, for example, gypsum boards 40 are attached to cover the side surfaces 1S, 1S and the underside 1B of the wooden beam 1 to form the fire-resistant covering 4. In this case, the upper edge surfaces of the gypsum boards 40 are attached in contact with the undersides of the non-combustible boards 6.

[0020] According to the construction method of the fire-resistant structure of embodiment 2, the upper edge 1e of the side surface 1S of the wooden beam 1 and the edge 2E of the flat deck 2 are spaced apart by a predetermined distance a in the direction along the horizontal plane, thereby achieving the same effect as the fire-resistant structure and construction method of embodiment 1 described above.

[0021] In the first embodiment, an example is shown in which a long material having an L-shaped cross section is used as the receiving material 5, but for example, a square timber or a crosspiece may also be used as the receiving material 5. That is, the support member 5 may be any member that extends along the extension direction of the wooden beam 1, is fixed to the upper edge 1e of the side surface 1S of the wooden beam 1, and on which the edge 2E side of the flat deck 2 can be placed. [Explanation of symbols]

[0022] 1 wooden beam, 1B bottom surface of wooden beam, 1S side of wooden beam, 1T top surface of wooden beam, 1e Upper edge of the side of the wooden beam, 2 Flat deck (steel deck plate for floor formwork), 2E Flat deck edge, 3 Slab, 4 Fireproof coating, 5 Support material, 6 Non-combustible board material, C. Concrete.

Claims

1. A fire-resistant structure in which a steel deck plate for floor formwork is provided between wooden beams, a slab is constructed on the steel deck plate for floor formwork and the wooden beams, and a fire-resistant covering is provided to cover the outer surface of the wooden beams, A fire-resistant structure characterized in that the upper edge of the side of the wooden beam is spaced apart from the edge of the steel deck plate for the floor formwork in a direction along the horizontal plane.

2. A construction method for the fire-resistant structure according to claim 1, a step of fixing a support material on which the edge side of the steel deck plate for floor formwork is placed to the upper edge side of the side of the wooden beam; a step of placing the edge side of the steel deck plate for the floor formwork on a support material so that the upper edge side of the side of the wooden beam and the edge side of the steel deck plate for the floor formwork are spaced apart in a direction along the horizontal plane; A step of pouring concrete onto the wooden beams, support members, and steel deck plates for floor formwork to construct a slab; A construction method for a fire-resistant structure, characterized by comprising the steps of: after constructing the slab, removing the support material and forming a fire-resistant covering to cover the sides and underside of the wooden beams.

3. A construction method for the fire-resistant structure according to claim 1, a step of fixing a non-combustible board to the upper surface of the wooden beam, the board being large enough to cover the upper surface of the wooden beam and have end faces positioned outward from the upper edges of the left and right sides of the wooden beam; a step of placing the edge side of the steel deck plate for floor formwork on the non-combustible plate material so that the upper edge side of the side of the wooden beam and the edge of the steel deck plate for floor formwork are spaced apart in a direction along the horizontal plane; A step of pouring concrete onto the non-combustible board material and the steel deck plate for floor formwork to construct a slab; and forming a fire-resistant covering to cover the sides and underside of the wooden beams.

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