Fireproof structure

Abstract

To provide a fireproof structure suppressing deflection of a floor part at high temperature.SOLUTION: A fireproof structure 1 comprises: fireproof beams 10 having a prescribed fireproof performance; fireproof columns, which have the prescribed fireproof performance and are connected to the fireproof beams so that a fireproof annular body 32 consists of a portion of the fireproof columns and the whole of the fireproof beams; reduced fireproof beams 35 that are disposed in the fireproof annular body without having the prescribed fireproof performance so that both ends thereof are connected to the fireproof beams; and a fireproof floor part 51, which has a tensile force transmission member 57 provided in a concrete 52 and outer peripheral edge 51a thereof so as to be supported by the fireproof annular body; and a non-fireproof floor part 61, which is formed of a material that burns or fuses at high temperature and fitted to an undersurface of the fireproof floor part and supported by the reduced fireproof beams. When directions intersecting each other on the top surface of the fireproof floor part are defined as a first intersection direction X and a second intersection direction Y, the tensile force transmission member transmits the tensile force between ends in the first intersection direction of the fireproof floor part and the tensile force between ends in the second intersection direction of the fireproof floor part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, fire-resistant structures have been known in which a reinforced concrete slab (floor section) is supported by a main beam (fire-resistant beam) with fire resistance and a sub-beam (reduced fire-resistant beam) with reduced fire-resistant coating (see, for example, Patent Document 1). In the fire-resistant structure of Patent Document 1, the minor beams are rigidly connected to the major beams. The slab is flat and supported by girders and sub-girders, to which horizontal steel plates are connected. With this configuration, the horizontal steel plates reinforce the connection structure between the main girder and the secondary girder, and the fire-resistant structure can ensure its strength in the event of a fire (high temperature). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6864991 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the event of a fire, the slab will deflect downward. In some fire-resistant structures, a fire wall (fire compartment) is located below the slab. In this case, the deflected slab may come into contact with the fire wall, and the load of the slab may act on the fire wall, potentially damaging it.

[0005] The present invention has been made in consideration of such problems, and has as its object to provide a fire-resistant structure in which deflection of the floor portion at high temperatures is suppressed. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention proposes the following means. (1) Aspect 1 of the present invention is a method for constructing a ring-shaped fire-resistant structure comprising: a plurality of fire-resistant beams having a predetermined fire resistance; a plurality of fire-resistant columns having the predetermined fire resistance and joined to the plurality of fire-resistant beams, with a portion of the columns and the entirety of the plurality of fire-resistant beams constituting a ring-shaped fire-resistant ring; a reduced fire-resistant beam that does not have the predetermined fire resistance and is placed inside the fire-resistant ring, with both ends joined to the plurality of fire-resistant beams; and a tensile force transmission member provided in the concrete, with the outer periphery of the beam being completely surrounded by the fire-resistant ring from below. and a non-fire-resistant floor section formed of a material that burns or melts at high temperatures, attached to the underside of the fire-resistant floor section, and supported from below by the fire-reducing beams, wherein when the directions that intersect with each other within the upper surface of the fire-resistant floor section are defined as a first intersecting direction and a second intersecting direction, the tensile force transmission member transmits the tensile force between the ends of the fire-resistant floor section in the first intersecting direction and the tensile force between the ends of the fire-resistant floor section in the second intersecting direction, respectively.

[0007] In this invention, reduced fire-resistance beams, each of whose ends is joined to a plurality of fire-resistance beams, are arranged inside the fire-resistant ring body. Therefore, during normal times when no fire has occurred, the non-fire-resistant floor section and the fire-resistant floor section can be supported not only by the fire-resistant ring body but also by the reduced fire-resistance beams. The outer periphery of the fire-resistant floor section is supported from below by a fire-resistant ring body that has a predetermined fire resistance and can maintain a certain level of rigidity and strength even at high temperatures during a fire, etc. The tensile force transmission members provided within the fire-resistant floor section transmit the tensile force between the ends of the fire-resistant floor section in the first cross direction and the tensile force between the ends of the fire-resistant floor section in the second cross direction.

[0008] At high temperatures, non-fire-resistant floor sections burn or melt. Furthermore, due to gravity and other factors acting on the fire-resistant floor section, the center of the fire-resistant floor section bends downward in a plan view, becoming convex. However, due to the membrane effect, the outer periphery of the fire-resistant floor section is supported by the fire-resistant ring body. The tensile force transmission members, which are stretched by the bending of the fire-resistant floor section, transmit tensile forces in the first intersecting direction and the second intersecting direction, respectively, thereby supporting the center of the fire-resistant floor section. Therefore, the fire resistance of the fire-resistant structure can be maintained at the same level as before. Even if the fire-resistant floor section bends downward, the non-fire-resistant floor section will burn and disappear or melt and melt off the fire-resistant floor section, thereby minimizing deflection of the fire-resistant and non-fire-resistant floor sections as a whole at high temperatures.

[0009] (2) Aspect 2 of the present invention may be the fire-resistant structure according to (1), in which the non-fire-resistant floor section is made of at least one of wood, plastic, and aluminum. In this invention, a non-fire-resistant floor section that burns or melts at high temperatures can be reliably constructed using at least one of wood, plastic, and aluminum, materials commonly used in fire-resistant structures. [Effects of the Invention]

[0010] In the fire-resistant structure of the present invention, deflection of the floor portion at high temperatures can be suppressed. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view schematically showing a fire-resistant structure according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along the line A1-A1 in FIG. [Figure 3] FIG. 2 is a plan view of the main parts of the non-fire-resistant floor section of the fire-resistant structure. [Figure 4] FIG. 2 is a cross-sectional view of a main part of the fireproof structure at high temperatures. [Figure 5] FIG. 10 is a cross-sectional view of a main part of a fire-resistant structure according to a first modified example of an embodiment of the present invention. [Figure 6] FIG. 10 is an exploded and cutaway perspective view of a main part of a fire-resistant structure according to a second modified example of one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, one embodiment of a fire-resistant structure according to the present invention will be described with reference to FIGS. As shown in Figures 1 and 2, the fire-resistant structure 1 of this embodiment includes a plurality of fire-resistant beams 10, a plurality of fire-resistant columns 30, a plurality of reduced fire-resistant beams 35, a floor 50, and a fire wall 85. Note that Figure 1 shows the floor 50 in a see-through manner. In Figure 1, columns and beams having fire-resistant covering performance, which will be described later, are shown hatched. Figures 1 to 3 show the configuration of the fire-resistant structure 1 at room temperature (normal). Room temperature here means, for example, between 0°C and 50°C. First, an overview of the floor portion 50 will be described below.

[0013] In this embodiment, the floor portion 50 is a flat plate that has a rectangular shape when viewed in the thickness direction of the floor portion 50. The floor portion 50 is disposed so that the thickness direction of the floor portion 50 is along the vertical direction Z. Here, "A is along (extends along) B" means that the angle formed between A and B is 30° or less. It is more preferable that this angle be 15° or less.

[0014] Here, directions that are perpendicular (intersect) with each other within the upper surface (plane) of the floor portion 50 are defined as a first intersecting direction X and a second intersecting direction Y. The first intersecting direction X is the longitudinal direction of the floor portion 50 when viewed in the vertical direction Z. The second intersecting direction Y is the lateral direction of the floor portion 50 when viewed in the vertical direction Z. The first intersecting direction X and the second intersecting direction Y are not particularly limited as long as they are directions that intersect with each other within the upper surface of the floor portion 50.

[0015] As shown in FIG. 1, the plurality of fire resistance beams 10 include two first fire resistance beams 11 and two second fire resistance beams 21. The two first fire-resistance beams 11 each extend along a first intersecting direction X. The two first fire-resistance beams 11 are disposed in a second intersecting direction Y at an interval from each other. The two second fire-resistance beams 21 each extend along the second intersecting direction Y. The two second fire-resistance beams 21 are disposed in the first intersecting direction X with a gap therebetween. Between the first fire resistance beam 11 and the second fire resistance beam 21, a gap S1 is formed in which the fire resistance column 30 is disposed.

[0016] As shown in Fig. 2, for example, the second fire resistance performance beam 21 is formed of an H-shaped steel 22 that is provided with a fire-resistant coating 27. The H-shaped steel 22 may be a rolled H-shaped steel or a welded assembled H-shaped steel. The H-shaped steel 22 has two flanges 23 and 24 and a web 25 joined to each of the flanges 23 and 24. The flange 23 is disposed higher than the flange 24. A headed stud 26 is fixed to the upper surface of the flange 23. The headed stud 26 extends upward from the flange 23. A heat insulating material such as rock wool or glass wool is used for the fire-resistant coating 27. In this case, the fire-resistant coating 27 is formed on the H-beam steel 22 by, for example, a spray coating method. Except for the length, the first fire-resistant beam 11 is configured in the same manner as the second fire-resistant beam 21. That is, the first fire-resistant beam 11 is formed of an H-shaped steel with a fire-resistant coating.

[0017] For example, the thickness of the fire-resistant coating 27, such as rock wool, on the second fire-resistance beam 21 is set in accordance with the "Construction Quality Control Guidelines for Sprayed Rockwool-Coated Fire-Resistant Structures (Spraying Division, Rockwool Industry Association)." If the second fire-resistance beam 21 is required to have a one-hour fire resistance, the thickness of the fire-resistant coating shall be 25 mm. Similarly, if the second fire-resistance beam 21 is required to have a two-hour fire resistance, the thickness of the fire-resistant coating shall be 45 mm. If the second fire-resistance beam 21 is required to have a three-hour fire resistance, the thickness of the fire-resistant coating shall be 60 mm. Hereinafter, the fire resistance performance based on the construction quality control guidelines for sprayed rock wool coated fire-resistant structures will be referred to as coated fire resistance performance (predetermined fire resistance performance). Each of the two second fire resistance beams 21 has coated fire resistance performance.

[0018] The predetermined fire resistance is not limited to the covering fire resistance, but may be, for example, the fire resistance based on the evaluation of the inherent fire resistance by the load heating test, the fire resistance based on the evaluation of the inherent fire resistance by the fire resistance verification method, etc. The first fire resistance beam 11 is the same as the second fire resistance beam 21. The fire-resistant coating may be formed by a formed plate method or a wrapping method. The fire-resistant beam may be made of reinforced concrete or steel-reinforced concrete. Gusset plates (not shown) are fixed by welding or the like to the webs of the two first fire-resistance beams 11. The gusset plates protrude toward the inside of the two first fire-resistance beams 11 in the second cross direction Y.

[0019] 1, for example, the fire-resistant columns 30 are formed of H-shaped steel with a fire-resistant coating. The plurality of fire-resistant columns 30 have the fire-resistant coating performance. The plurality of fire-resistant columns 30 extend along the vertical direction Z. In this embodiment, the upper ends of the plurality of fire-resistant columns 30 are respectively arranged in the gap S1. The ends of the plurality of fire-resistant beams 10 are rigidly joined to (a portion of) the upper ends of the plurality of fire-resistant columns 30. The upper ends of the plurality of fire-resistant columns 30 and the plurality of fire-resistant beams 10 as a whole constitute a square-ring (annular) fire-resistant ring body 32. In other words, the fire-resistant ring body 32 surrounds the region R1. In addition, the fire-resistant column may be formed from any of a square steel pipe with a fire-resistant coating, a circular steel pipe with a fire-resistant coating, a concrete-filled steel pipe, reinforced concrete, and steel-reinforced concrete.

[0020] As shown in FIG. 2, in this embodiment, the reduced fire resistance beam 35 is formed of an H-shaped steel 36 that is coated with a fire-resistant coating (not shown). However, the reduced fire resistance beam 35 has less fire-resistant coating than the fire-resistant beam 10. For example, the thickness of the fire-resistant coating in the reduced fire resistance beam 35 is set to about 1 / 10 to 1 / 2 of the thickness of the fire-resistant coating based on the fire resistance performance of each coating. Therefore, the multiple reduced fire resistance beams 35 do not have coating fire resistance. The H-shaped steel 36 has two flanges 37 and 38 and a web 39 joined to each of the flanges 37 and 38. The flange 37 is disposed higher than the flange 38. In addition, the reduced fire resistance beam does not need to have a fire-resistant coating.

[0021] 1, the plurality of reduced fire resistance beams 35 each extend along the second transverse direction Y and are spaced apart from one another in the first transverse direction X. The plurality of reduced fire resistance beams 35 are disposed within the fire-resistant ring 32. Both ends of the multiple reduced fire resistance beams 35 are respectively joined to the multiple fire resistance beams 10. Specifically, both ends of the multiple reduced fire resistance beams 35 are fixed to the gusset plates of the two first fire resistance beams 11 by bolts (not shown) or the like.

[0022] As shown in FIG. 2, the floor section 50 has a fire-resistant floor section 51, a non-fire-resistant floor section 61, a plurality of headed studs 66, connecting bars 71, and a surface material 81. The fire-resistant floor section 51 is formed of a reinforced concrete slab. The fire-resistant floor section 51 is constructed by providing a tensile force transmission member 57 in concrete 52. The concrete 52 has a fire-resistant main body 53 and a plurality of support sections 54. Note that only one of the plurality of support sections 54 is shown in FIG. 2. The fire-resistant portion main body 53 has a rectangular flat plate shape when viewed in the vertical direction Z. The support parts 54 are fixed to the outer peripheral edge of the lower surface 53a of the fire-resistant part main body 53. The support parts 54 protrude downward from the lower surface 53a of the fire-resistant part main body 53. For example, the multiple support parts 54 are respectively arranged above the two first fire-resistant beams 11 and above the two second fire-resistant beams 21. The support parts 54 are shaped to fit into fitting holes 62 (described later) of the non-fire-resistant floor part 61 (see also FIG. 3).

[0023] It is preferable that the multiple support parts 54 are arranged without any gaps above the fire-resistant ring body 32. In this case, the outer peripheral edge 51a of the fire-resistant floor part 51 is supported by the fire-resistant ring body 32 from below the outer peripheral edge 51a all around.

[0024] The tensile force transmission member 57 has a plurality of first reinforcing bars 58 and a plurality of second reinforcing bars 59. Note that only one of the plurality of first reinforcing bars 58 is shown in FIG. The plurality of first reinforcing bars 58 are arranged in the concrete 52 over the entire length between both ends of the concrete 52 in the first transverse direction X. The plurality of first reinforcing bars 58 extend along the first transverse direction X. The plurality of first reinforcing bars 58 are arranged at intervals from one another in the second transverse direction Y. The plurality of second reinforcing bars 59 are arranged in the concrete 52 over the entire length between both ends of the concrete 52 in the second transverse direction Y. The plurality of second reinforcing bars 59 extend along the second transverse direction Y. The plurality of second reinforcing bars 59 are arranged at intervals from one another in the first transverse direction X.

[0025] The tensile force transmission members 57 transmit the tensile force between the ends of the fire-resistant floor section 51 in the first intersecting direction X and the tensile force between the ends of the fire-resistant floor section 51 in the second intersecting direction Y, respectively. For example, during normal times when no fire has occurred and during a fire (high temperature), the tensile force transmission member 57 transmits the tensile force in the first intersecting direction X generated at the end of the fire-resistant floor section 51 on a first side in the first intersecting direction X to the end of the fire-resistant floor section 51 on a second side in the first intersecting direction X by the multiple first reinforcing bars 58. Furthermore, the tensile force transmission member 57 transmits the tensile force generated at the end of the second side of the fire-resistant floor section 51 to the end of the first side of the fire-resistant floor section 51 by the multiple first reinforcing bars 58. This tensile force is generated by the weight of the fire-resistant floor section 51, equipment placed on the fire-resistant floor section 51, etc. High temperatures here refer to, for example, temperatures according to the heating curve specified in ISO 834-11:2014 or temperatures of 260°C or higher. The same applies to the second intersecting direction Y as to the first intersecting direction X.

[0026] The fire-resistant floor may be formed of a composite slab having, for example, a deck plate and concrete placed on the deck plate, in which case the deck plate constitutes the tensile force transmission member.

[0027] 2 and 3, the non-fire-resistant floor portion 61 is a flat plate that has a rectangular shape when viewed in the vertical direction Z. A plurality of fitting holes 62 are formed in the non-fire-resistant floor portion 61 at positions corresponding to the plurality of support portions 54 of the concrete 52. The fitting hole 62 has a large diameter hole 62a and a small diameter hole 62b. The fitting hole 62 (hereinafter also referred to as fitting hole 62B) formed above the second fire resistance beam 21 will be described below.

[0028] The large diameter hole 62a is formed in the upper surface of the non-fire-resistant floor portion 61, and reaches the middle portion of the non-fire-resistant floor portion 61 in the vertical direction Z. The large diameter hole 62a extends along the first intersecting direction X. The small diameter hole 62b is formed in a middle portion in the second intersecting direction Y and a middle portion in the first intersecting direction X on the bottom surface of the large diameter hole 62a. The large diameter hole of the fitting hole 62 formed above the first fire resistance beam 11 extends along the second intersecting direction Y.

[0029] The non-fire-resistant floor section 61 is made of a material that burns at high temperatures. Specifically, in this embodiment, the non-fire-resistant floor section 61 is made of wood. Preferred wood species include Douglas fir, Japanese larch, larch, cedar, and cypress. The non-fire-resistant floor section 61 may be made of solid wood or may be made of composite material such as CLT (Cross Laminated Timber). The non-fire-resistant floor section may be made of a material that burns or melts at high temperatures. Specifically, the non-fire-resistant floor section may be made of at least one of wood, plastic, and aluminum. A support portion 54 of concrete 52 is placed in each fitting hole 62 of the non-fire-resistant floor portion 61. The headed studs 26 of the second fire-resistant beam 21 are placed in the fire-resistant portion main body 53 and support portion 54 of the concrete 52.

[0030] As shown in Figure 2, the lower portions of the headed studs 66 are fixed to the upper part of the non-fire-resistant floor section 61. The upper portions of the headed studs 66 protrude above the non-fire-resistant floor section 61. This portion is located within the fire-resistant body 53 of the concrete 52. The second fire-resistant beam 21 directly supports the support portion 54 of the fire-resistant floor portion 51 from below the support portion 54. The first fire-resistant beam 11 is similar to the second fire-resistant beam 21.

[0031] The non-fire-resistant floor section 61 is attached to the underside of the fire-resistant floor section 51. The non-fire-resistant floor section 61 is supported from below by a plurality of reduced fire-resistance beams 35 and fire-resistant ring bodies 32. In this embodiment, the plurality of reduced fire-resistance beams 35 support only the non-fire-resistant floor section 61 of the floor section 50. The non-fire-resistant floor portion 61 does not have to be supported by the fire-resistant ring body 32 .

[0032] 2 and 3, the tie bar 71 has a reinforcing bar body 72, two inclined pieces 73, and two end pieces 74. The reinforcing bar body 72, the two inclined pieces 73, and the two end pieces 74 are each formed in a rod shape.

[0033] The reinforcing bar main body 72 extends along the first intersecting direction X. The reinforcing bar main body 72 is disposed in the large diameter hole 62a near the bottom surface of the large diameter hole 62a. The two inclined pieces 73 extend from each end of the reinforcing bar main body 72 in the first intersecting direction X, gradually inclining upward as they move away from the reinforcing bar main body 72. First ends of the two inclined pieces 73 opposite the ends connected to the reinforcing bar main body 72 protrude above the non-fire-resistant floor portion 61. The lower portions of the reinforcing bar body 72 and the two inclined pieces 73 are placed within the support portion 54 of the concrete 52. The two end pieces 74 extend from first ends of the two inclined pieces 73 along the first intersecting direction X so as to be spaced apart from the reinforcing bar main body 72. The upper portions of the two end pieces 74 and the two inclined pieces 73 are disposed within the fire-resistant main body 53 of the concrete 52. As described above, the tie bars 71 are arranged in the concrete 52.

[0034] For example, the surface material 81 is made of a material that will not burn or melt in the event of a fire. Specifically, the surface material 81 is made of a gypsum-based pourable floor underlayment material that has self-leveling properties, such as SL Plaster (manufactured by Yoshino Gypsum Co., Ltd.). The surface material 81 is placed on the fire-resistant portion main body 53 of the concrete 52. For example, the fire wall 85 is a flat plate whose thickness direction is along the first intersecting direction X. The fire wall 85 is made of gypsum, mortar, or the like. For example, the fire wall 85 is disposed below the non-fire-resistant floor portion 61 of the floor portion 50. The upper end of the fire wall 85 reaches near the non-fire-resistant floor portion 61 of the floor portion 50.

[0035] In the fire-resistant structure 1 configured as above, the following steps are carried out when constructing the floor section 50. A plurality of fire-resistant beams 10, a plurality of fire-resistant columns 30, and a plurality of reduced fire-resistant beams 35 are constructed in advance. A non-fire-resistant floor section 61, a plurality of headed studs 66, ties 71, and a tensile force transmission member 57 are disposed on the fire-resistant ring 32 and the plurality of reduced fire-resistance beams 35. Concrete is poured onto the non-fire-resistant floor section 61 to form the concrete 52 having the fire-resistant main body 53 and a plurality of support sections 54. Then, the fire-resistant floor section 51 is formed with the tensile force transmission member 57 provided in the concrete 52. By carrying out the above steps, the floor section 50 having the fire-resistant floor section 51, the non-fire-resistant floor section 61, etc. is constructed.

[0036] As described above, in the fire-resistant structure 1 of this embodiment, a plurality of reduced fire-resistance beams 35, each of whose both ends is joined to a plurality of fire-resistance beams 10, are arranged within the fire-resistant ring 32. Therefore, during normal times when no fire has occurred, the non-fire-resistant floor section 61 and the fire-resistant floor section 51 can be supported not only by the fire-resistant ring 32 but also by the plurality of reduced fire-resistance beams 35. The outer peripheral edge 51a of the fire-resistant floor section 51 is supported from below by a fire-resistant ring 32 that has fire-resistant coating and can maintain a certain level of rigidity and strength even at high temperatures such as during a fire. Tensile force transmission members 57 provided within the fire-resistant floor section 51 transmit the tensile force between the ends of the fire-resistant floor section 51 in the first transverse direction X and the tensile force between the ends of the fire-resistant floor section 51 in the second transverse direction Y.

[0037] As shown in FIG. 4, at high temperatures, the non-fire-resistant floor section 61 burns and disappears, and the multiple fire-reducing beams 35 deform downward. Furthermore, due to gravity and other factors acting on the fire-resistant floor section 51, the center of the fire-resistant floor section 51 in a plan view bends downward and becomes convex. However, due to the membrane effect, the outer periphery 51a of the fire-resistant floor section 51 is supported by the fire-resistant ring 32. The tensile force transmission members 57, which are stretched by the bending of the fire-resistant floor section 51, transmit tensile forces in the first intersecting direction X and the second intersecting direction Y, thereby supporting the center of the fire-resistant floor section 51. Therefore, the fire resistance of the fire-resistant structure 1 can be maintained at the same level as before. Even if the fire-resistant floor section 51 bends downward, the non-fire-resistant floor section 61 will burn and disappear. Therefore, bending (downward displacement) of the fire-resistant floor section 51 and the non-fire-resistant floor section 61 as a whole at high temperatures can be suppressed.

[0038] Even if the fire-resistant floor section 51 bends downward, the non-fire-resistant floor section 61 is less likely to come into contact with the fire wall 85. Therefore, the fire wall 85 located below the fire-resistant floor section 51 and the non-fire-resistant floor section 61 can be prevented from being damaged by the fire-resistant floor section 51 and the non-fire-resistant floor section 61 at high temperatures. The fire-resistant beams 10 support the multiple support parts 54 of the fire-resistant floor part 51. For this reason, for example, if a fire breaks out below the region R1 and spreads to the non-fire-resistant floor part 61, the multiple concrete support parts 54 can prevent the fire from spreading outward beyond the fire-resistant ring 32 in the first intersecting direction X and the second intersecting direction Y.

[0039] The non-fire-resistant floor section 61 is made of wood. Therefore, the non-fire-resistant floor section 61, which burns at high temperatures, can be reliably constructed using wood, a material that is widely used in fire-resistant structures. The fire-resistant floor section 51 is formed of a reinforced concrete slab. Since reinforced concrete slabs are widely used as floor sections, the fire-resistant floor section 51 can be constructed inexpensively.

[0040] The tensile force transmission member 57 has a plurality of first reinforcing bars 58 and a plurality of second reinforcing bars 59. Therefore, with a simple configuration of a plurality of first reinforcing bars 58 and a plurality of second reinforcing bars 59, the tensile force between the ends of the fire-resistant floor section 51 in the first transverse direction X and the tensile force between the ends of the fire-resistant floor section 51 in the second transverse direction Y can be transmitted. The second fire-resistant beam 21 (fire-resistant beam 10) is formed of an H-shaped steel 22 with a fire-resistant coating 27. H-shaped steel with a fire-resistant coating is widely used as a beam with fire resistance, so the second fire-resistant beam 21 can be constructed inexpensively.

[0041] The fire-resistant column 30 is formed of an H-shaped steel with a fire-resistant coating. Since the H-shaped steel with a fire-resistant coating is widely used as a column with fire resistance, the fire-resistant column 30 can be constructed inexpensively. The fire-resistant coating 27 is formed by a spray coating method, which is widely used to apply fire-resistant coatings to H-shaped steel beams and the like, and therefore the fire-resistant coating 27 can be applied inexpensively.

[0042] The configuration of the fire-resistant structure 1 of this embodiment can be modified in various ways as described below. As in a fire-resistant structure 1A of a first modified example shown in FIG. 5, a reduced fire resistance beam 35 may directly support a fire-resistant floor portion 51A and a non-fire-resistant floor portion 61A of a floor portion 50A. Specifically, the concrete 52 of the fire-resistant floor portion 51A has a support portion 54 arranged above the reduced fire-resistant beam 35. The non-fire-resistant floor portion 61A has a fitting hole 62B formed therein, into which the support portion 54 is placed. In the fire-resistant structure 1A of the first modified example, the reduced fire resistance beam 35 supports not only the non-fire-resistant floor portion 61A of the floor portion 50A but also the support portion 54 of the fire-resistant floor portion 51A.

[0043] By configuring the fire-resistant structure 1A as in the first modified example, the concrete support portion 54 can prevent flames that have spread to the non-fire-resistant floor portion 61A from spreading beyond the reduced fire-resistant beam 35 in the first intersecting direction X.

[0044] As in a fire-resistant structure 1B of a second modified example shown in Fig. 6, the reduced fire resistance beam 90 may be made of a material that burns or melts at high temperatures. For example, in the fire-resistant structure 1B, the reduced fire resistance beam 90 is made of wood. Specifically, a connector 100 is fixed to the web 15 of the first fire resistance beam 11.

[0045] The connector fitting 100 is provided at a portion of the first fire resistance beam 11 that is joined to the reduced fire resistance beam 90. For example, the connector fitting 100 has a first plate piece 101 and a second plate piece 102. The plates 101 and 102 are formed of steel plates or the like. The second plate piece 102 has a plurality of through holes 102a formed therein that penetrate the second plate piece 102 in the thickness direction. The second plate piece 102 protrudes from the first surface of the first plate piece 101 in the thickness direction of the first plate piece 101. The first plate piece 101 and the second plate piece 102 are joined to each other by welding or the like. The connector 100 has a T-shape when viewed in a direction perpendicular to the thickness direction of the first plate piece 101 and the second plate piece 102.

[0046] A second surface of the first plate piece 101 opposite to the first surface is in contact with the web 15 of the first fire-resistant beam 11. The first plate piece 101 is fixed to the web 15 of the first fire-resistant beam 11 by a bolt 103.

[0047] The reduced fire resistance beam 90 extends along the second intersecting direction Y. At each end of the reduced fire resistance beam 90 in the second intersecting direction Y, a fitting groove 91 and a plurality of through holes 92 are formed.

[0048] The fitting groove 91 has a wide portion 91a and a narrow portion 91b. The wide portion 91a is formed in the middle of the end face of the reduced fire resistance beam 90 in the second transverse direction Y in the first transverse direction X. The wide portion 91a protrudes toward the inside of the reduced fire resistance beam 90 in the second transverse direction Y. A first plate piece 101 of the connecting fitting 100 is disposed within the wide portion 91a. The narrow portion 91b is formed in the middle of the bottom surface of the wide portion 91a in the first intersecting direction X. The narrow portion 91b protrudes toward the inside of the reduced fire resistance beam 90 in the second intersecting direction Y. The length of the narrow portion 91b in the first intersecting direction X is shorter than the length of the wide portion 91a in the first intersecting direction X. The second plate piece 102 of the connecting fitting 100 is arranged within the narrow portion 91b. In this example, the wide portion 91a and the narrow portion 91b penetrate the reduced fire resistance beam 90 in the vertical direction Z.

[0049] The plurality of through holes 92 each extend along the first intersecting direction X. The plurality of through holes 92 open to the narrow width portion 91b of the fitting groove 91. The plurality of through holes 92 are arranged side by side in the up-down direction Z. A plurality of dowels 93 are used to connect the connecting fitting 100 and the reduced fire resistance beam 90. Each dowel 93 is formed into a rod shape from wood or the like. The plurality of dowels 93 are respectively arranged in the plurality of through holes 92 of the reduced fire resistance beam 90 and the plurality of through holes 102a of the connecting fitting 100. For example, the plurality of dowels 93 are fixed to the reduced fire resistance beam 90 with an adhesive (not shown). In this way, both ends of the reduced fire resistance beam 90 are joined to the first fire resistance beam 11.

[0050] The reduced fire resistance beam 90 configured as described above supports the non-fire resistance floor portion 61 of the floor portion 50 from below the non-fire resistance floor portion 61. For example, the reduced fire resistance beam 90 and the non-fire resistance floor portion 61 are connected by nails, screws, lug screw bolts, etc. The fireproof structures 1A and 1B of the modified examples configured as above can also achieve the same effects as the fireproof structure 1 of this embodiment.

[0051] The above describes in detail one embodiment of the present invention and its modified examples with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes modifications, combinations, deletions, etc. of the configuration within the scope that does not deviate from the gist of the present invention. For example, in the above-described embodiment and modified examples, the number of reduced fire resistance beams 35, 90 provided in the fire-resistant structure may be one.

[0052] The floor portion 50 may be disposed so that the thickness direction intersects with the vertical direction Z. The part of the fire-resistant column 30 is not limited to the upper end of the fire-resistant column 30, but may be the middle part of the fire-resistant column 30 in the vertical direction Z. In this case, the fire-resistant column 30 protrudes upward beyond the floor portion 50. The fire-resistant structure may not include at least one of the plurality of headed studs (26, 66), the ties (71), the facing (81), and the fire wall (85). [Explanation of symbols]

[0053] 1,1A,1B Fireproof structure 10 Fire resistance beam 30 Fire resistance performance pillar 32 Refractory ring 35,90 Reduced fire resistance beam 51,51A Fire resistance floor section 51a outer edge 52 Concrete 57 Tensile force transmission member 61,61A Non-fire resistant flooring X 1st cross direction Y Second cross direction

Claims

1. A plurality of fire-resistant beams having a predetermined fire resistance; A plurality of fire-resistant columns having the predetermined fire resistance, joined to the plurality of fire-resistant beams, and forming an annular fire-resistant ring body with a part of the columns and the entire plurality of fire-resistant beams; A reduced fire resistance beam that does not have the predetermined fire resistance and is arranged inside the fire resistance annular body, and both ends of which are joined to the plurality of fire resistance beams, respectively; a fire-resistant floor section in which a tensile force transmission member is provided in the concrete and whose outer peripheral edge is supported from below over its entire periphery by the fire-resistant ring body; A non-fire-resistant floor section formed of a material that burns or melts at high temperatures, attached to the underside of the fire-resistant floor section, and supported from below by the reduced fire-resistant beam; Equipped with When the directions intersecting each other within the upper surface of the fire-resistant floor section are defined as a first intersecting direction and a second intersecting direction, A fire-resistant structure in which the tensile force transmission member transmits the tensile force between the ends of the fire-resistant floor section in the first cross direction and the tensile force between the ends of the fire-resistant floor section in the second cross direction.

2. The fire-resistant structure according to claim 1, wherein the non-fire-resistant floor section is made of at least one of wood, plastic, and aluminum.

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