Fireproof structure design method, fireproof structure construction method, and fireproof structure

Abstract

To provide a design method of a fire resistance structure allowing connection parts of reduced fire resistance covering beam while maintaining fire resistance efficiency.SOLUTION: A design method S10 of a fire resistance structure comprises a structure setting process S11 of setting arrangements of a floor part, a plurality of beams supporting the floor part from below and a plurality of columns connected to the plurality of beams, a first fire resistance specification setting process S13 of setting that the surrounding of the floor part is supported by the plurality of fire resistance covering beams obtained by applying a fire resistance covering to a part of the plurality of beams, a second fire resistance specification setting process S15 of applying the fire resistance covering to the plurality of columns and setting them as a plurality of fire resistance covering columns and a third fire resistance specification setting process S17 of connecting an end of a reduced fire resistance covering beam to the fire resistance covering beam and setting that it supports the floor part from below while arranging the reduced fire resistance covering beam which is a remaining portion of the plurality of beams or the reduced fire resistance covering beam obtained by applying the fire resistance covering to the remaining portion of the plurality of beams in the area, and in the third fire resistance specification setting process, the reduced fire resistance covering beam is set to be arranged along a longitudinal direction of the floor part when seen in a thickness direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a design method for a fireproof structure, a construction method for a fireproof structure, and a fireproof structure. [Background technology]

[0002] Conventionally, in fire-resistant structures, a slab (floor section) is supported by girders and steel frame girders (beams with reduced fire-resistant coating) (see, for example, Patent Document 1). The girders are made of reinforced concrete and are placed between the columns. The steel frame girders are H-shaped steel beams that are not entirely treated with fire-resistant coating. The steel frame girders are integrated with the slab by multiple studs welded to the upper flanges.

[0003] In the event of a fire, the heat can reduce the load-bearing capacity of the steel girders or cause them to melt. However, the slab is designed to be thick enough to withstand long-term loads even without the steel girders. Therefore, the strength of the slab itself prevents the slab from falling off. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-190586 A Summary of the Invention [Problem to be solved by the invention]

[0005] Fire-resistant coated beams may be used as the main beams. The steel beams are arranged along the short side of the slab, which has a rectangular shape when viewed in the thickness direction. In this case, multiple steel beams are arranged at intervals along the length of the floor. Each steel beam is joined to the fire-resistant covered beam at two points on both ends. Since the longitudinal length of the floor section is longer than the lateral length of the floor section, when the steel beams are arranged along the lateral direction, there are many points where the steel beams are joined to the main beams.

[0006] The present invention has been made in consideration of such problems, and aims to provide a design method for a fire-resistant structure, a construction method for a fire-resistant structure, and a fire-resistant structure that can reduce the number of points where a reduced fire-resistant coated beam is joined to a fire-resistant coated beam while maintaining fire resistance performance. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following means. (1) A first aspect of the present invention includes a floor section having a rectangular shape when viewed in the thickness direction and in which a tensile force transmission member is provided in concrete, a plurality of fire-resistant coated beams that are fire-resistant coated and support the periphery of the floor section from below, a plurality of fire-resistant coated columns that are fire-resistant coated and joined to ends of the plurality of fire-resistant coated beams, with a part of the columns and the plurality of fire-resistant coated beams forming a ring shape as a whole, and a reduced-fire-resistant coated beam that has less fire-resistant coating than the fire-resistant coated beams, is joined to ends of the plurality of fire-resistant coated beams, is arranged in an area surrounded by the plurality of fire-resistant coated beams and the plurality of fire-resistant coated columns, and has ends joined to the plurality of fire-resistant coated beams to support the floor section from below, and when directions that intersect with each other in the plane of the floor section are defined as a first intersecting direction and a second intersecting direction, the tensile force transmission member transmits a tensile force between ends of the floor section in the first intersecting direction and a tensile force between ends of the floor section in the second intersecting direction, respectively. A design method for a fire-resistant structure, comprising: a structural setting step of setting the arrangement of the floor, a plurality of beams supporting the floor from below, and a plurality of columns joined to the plurality of beams by performing structural calculations; a first fire resistance specification setting step of setting the periphery of the floor to be supported from below by a plurality of fire-resistant coated beams having a fire-resistant coating applied to a portion of the plurality of beams; a second fire resistance specification setting step of applying a fire-resistant coating to the plurality of columns and setting them as the plurality of fire-resistant coated columns; and a third fire resistance specification setting step of arranging the reduced fire-resistant coated beam, which is the remaining portion of the plurality of beams, or the reduced fire-resistant coated beam having a fire-resistant coating applied to the remaining portion of the plurality of beams, within the region and joining the end of the reduced fire-resistant coated beam to the fire-resistant coated beam to support the floor from below, and in the third fire resistance specification setting step, setting the reduced fire-resistant coated beam to be arranged along the longitudinal direction of the floor when viewed in the thickness direction.

[0008] The term "a tensile force transmission member is provided in concrete" as used herein also means that a part of the tensile force transmission member is exposed from the concrete.

[0009] (2) In the design method for a fire-resistant structure described in (1) above, the reduced fire-resistance coating beam may have an H-shaped steel. (3) In the design method for a fire-resistant structure described in (1) or (2) above, when the floor portion is viewed in the thickness direction, the ratio of the longitudinal length to the transverse length may exceed 1.52.

[0010] (4) In the design method for a fire-resistant structure described in any one of (1) to (3), the floor portion may be a composite slab or a reinforced concrete slab. (5) In the design method for a fire-resistant structure described in any one of (1) to (4), the tensile force transmission member may have a first reinforcing bar extending along the first intersecting direction and transmitting a tensile force between the ends of the floor section in the first intersecting direction, and a second reinforcing bar extending along the second intersecting direction and transmitting a tensile force between the ends of the floor section in the second intersecting direction.

[0011] (6) In the design method for a fire-resistant structure described in (5), the first intersecting direction is the longitudinal direction of the floor portion when viewed in the thickness direction, the second intersecting direction is the transverse direction of the floor portion when viewed in the thickness direction, and the ratio of the cross-sectional area of ​​the second reinforcing bar to the cross-sectional area of ​​the concrete in a cross section perpendicular to the transverse direction may be greater than the ratio of the cross-sectional area of ​​the first reinforcing bar to the cross-sectional area of ​​the concrete in a cross section perpendicular to the longitudinal direction. (7) In the design method for a fire-resistant structure described in any one of (1) to (6), the fire-resistant coated beam may be an H-shaped steel beam, a reinforced concrete beam, or a steel-reinforced concrete beam, to which the fire-resistant coating is applied.

[0012] (8) In the design method for a fire-resistant structure described in any one of (1) to (7), the fire-resistant coated column may be an H-shaped steel beam coated with the fire-resistant coating, a square steel pipe coated with the fire-resistant coating, a circular steel pipe coated with the fire-resistant coating, a concrete-filled steel pipe structure, a reinforced concrete structure, or a steel-reinforced concrete structure. (9) In the design method for a fire-resistant structure according to any one of (1) to (8), the fire-resistant coating may be applied by a spraying method, a molded plate method, or a wrapping method.

[0013] (10) In the design method for a fire-resistant structure described in any one of (1) to (9), the longitudinal length of the floor section when viewed in the thickness direction may exceed 11 m.

[0014] (11) A second aspect of the present invention is a floor section having a rectangular shape when viewed in the thickness direction, in which a tensile force transmission member is provided in concrete, a plurality of fire-resistant coated beams that are fire-resistant coated and support the periphery of the floor section from below, a plurality of fire-resistant coated columns that are fire-resistant coated and joined to ends of the plurality of fire-resistant coated beams, so that a part of the fire-resistant coated columns and the plurality of fire-resistant coated beams as a whole are formed into a ring shape, and a reduced-fire-resistant coated beam that has less fire-resistant coating than the fire-resistant coated beams, is joined to ends of the plurality of fire-resistant coated beams, is arranged in an area surrounded by the plurality of fire-resistant coated beams and the plurality of fire-resistant coated columns, and has ends joined to the plurality of fire-resistant coated beams to support the floor section from below, and when directions that intersect with each other in the plane of the floor section are defined as a first intersecting direction and a second intersecting direction, the tensile force transmission member transmits a tensile force between ends of the floor section in the first intersecting direction and a tensile force between ends of the floor section in the first intersecting direction and a tensile force between ends of the floor section in the second intersecting direction. a column-beam construction process for constructing the floor section, a plurality of beams supporting the floor section from below, and a plurality of columns joined to the plurality of beams; a first covering process for supporting the periphery of the floor section from below with annular fire-resistant coated beams having a fire-resistant coating applied to a portion of the plurality of beams; a second covering process for applying a fire-resistant coating to the plurality of columns to form the plurality of fire-resistant coated columns; and a third covering process for arranging the reduced fire-resistant coated beams, which are the remaining portions of the plurality of beams, or the reduced fire-resistant coated beams having a fire-resistant coating applied to the remaining portions of the plurality of beams, within the region and joining the ends of the reduced fire-resistant coated beams to the fire-resistant coated beams to support the floor section from below, and in the third covering process, the reduced fire-resistant coated beams are arranged along the longitudinal direction of the floor section when viewed in the thickness direction.

[0015] (12) A third aspect of the present invention includes a floor section having a tensile force transmission member provided in concrete and having a rectangular shape when viewed in the thickness direction, a plurality of fire-resistant coated beams that are fire-resistant coated and support the periphery of the floor section from below, a plurality of fire-resistant coated columns that are fire-resistant coated and joined to ends of the plurality of fire-resistant coated beams so that a part of the columns and the plurality of fire-resistant coated beams as a whole are formed into a ring shape, and a plurality of fire-resistant coated columns having a reduced fire-resistant coating compared to the fire-resistant coated beams and joined to ends of the plurality of fire-resistant coated beams so as to form a ring shape between the plurality of fire-resistant coated beams and the plurality of fire-resistant coated columns. and a reduced fire-resistant coated beam arranged within an area surrounded by the covered columns and having its ends joined to the multiple fire-resistant coated beams to support the floor section from below, wherein when the directions in which they intersect within the plane of the 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 floor section in the first intersecting direction and the tensile force between the ends of the floor section in the second intersecting direction, respectively, and the reduced fire-resistant coated beam is arranged along the longitudinal direction of the floor section when viewed in the thickness direction. Effect of the Invention

[0016] The design method for a fire-resistant structure, the construction method for a fire-resistant structure, and the fire-resistant structure of the present invention can reduce the number of points where a reduced fire-resistant coated beam joins to a fire-resistant coated beam while maintaining fire resistance performance. [Brief description of the drawings]

[0017] [Figure 1] 1 is a perspective view showing a fireproof structure according to one embodiment of the present invention; [Diagram 2] 2 is a cross-sectional view taken along line A1-A1 in FIG. [Diagram 3] FIG. 2 is a perspective view of a reinforcing bar in the fire-resistant structure. [Figure 4] 1 is a flowchart showing a method for designing a fire-resistant structure in one embodiment of the present invention. [Diagram 5] FIG. 2 is a perspective view of a foundation structure in the design method for a fire-resistant structure. [Figure 6] 1 is a flowchart showing a construction method for a fire-resistant structure in one embodiment of the present invention. [Figure 7] FIG. 2 is an exploded perspective view of the fireproof structure, illustrating external forces that normally act on the fireproof structure. [Figure 8] FIG. 2 is an exploded perspective view of the fireproof structure, illustrating an external force acting on the fireproof structure in the event of a fire. [Figure 9] FIG. 2 is a plan view showing the fireproof structures of the example and the comparative example stacked together. [Figure 10] FIG. 2 is a perspective view showing an outline of an analysis model of the fireproof structure of the embodiment. [Figure 11] FIG. 1 is a perspective view showing an overview of an analytical model of a fire-resistant structure of a comparative example. [Figure 12] FIG. 11 is a perspective view showing an example of a simulation result of the fireproof structure of the embodiment. [Figure 13] FIG. 11 is a perspective view showing an example of a simulation result of a fire-resistant structure of a comparative example. [Figure 14] FIG. 13 is a diagram showing an example of a simulation result of determining a change in deflection with respect to a combustion time. [Figure 15] FIG. 13 is a graph showing the change in time until the end of the simulation versus the length of the first fire-resistant coated beam. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of a fireproof structure, a method for designing a fireproof structure, and a method for constructing a fireproof structure according to the present invention will be described with reference to Figs. As shown in Figures 1 and 2, the fireproof structure 1 of this embodiment includes a floor section 10, a plurality of fireproof-coated beams 25, a plurality of fireproof-coated columns 35, and a reduced-fireproof-coated beam 40. Note that in Figure 1, the floor section 10 is shown in a see-through manner. In Figure 1 and Figures 7 to 9 described later, columns and beams to which the fireproof coating is applied without being reduced are shown with hatching. The floor portion 10 has a flat plate shape. When viewed in a thickness direction Z of the floor portion 10, the floor portion 10 has a rectangular shape having a plurality of corners 10a.

[0019] In this embodiment, the floor portion 10 is disposed so that the thickness direction Z is aligned with the vertical direction. Note that the floor portion 10 may be disposed so that the thickness direction Z intersects with the vertical direction. Here, the directions that are perpendicular (intersect) with each other on the upper surface (plane) of the floor portion 10 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 10 when viewed in the thickness direction Z. The second intersecting direction Y is the lateral direction of the floor portion 10 when viewed in the thickness 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 10. Hereinafter, when the floor portion 10 is viewed in the thickness direction Z, the ratio of the length in the longitudinal direction to the length in the lateral direction is referred to as the aspect ratio of the floor portion 10.

[0020] 2, the floor section 10 is a so-called reinforced concrete slab. The floor section 10 includes a deck plate 11, concrete 12, and reinforcing bars (tensile force transmission members) 13. For example, the deck plate 11 is formed by bending a steel plate. However, in this example, the deck plate 11 is treated as a formwork for the concrete 12, and is designed not to exhibit a composite effect with the concrete 12. The concrete 12 has the same shape as the floor portion 10 when viewed in the thickness direction Z. The concrete 12 is placed on the deck plate 11. The deck plate 11 and the reinforcing bars 13 are provided in the concrete 12. Here, "the deck plate 11 and the reinforcing bars 13 are provided in the concrete 12" also means that parts of the deck plate 11 and the reinforcing bars 13 are exposed from the concrete 12.

[0021] The configuration of the reinforcing bar 13 is not particularly limited as long as it includes a first reinforcing bar extending along the first intersecting direction X and a second reinforcing bar extending along the second intersecting direction Y. As shown in Fig. 2 and Fig. 3, in this embodiment, the reinforcing bar 13 includes a plurality of first reinforcing bars 15 and a plurality of second reinforcing bars 16, 17. It should be noted that a first connecting member 19, which will be described later, is not shown in FIG.

[0022] Each first reinforcing bar 15 extends along a first transverse direction X. The multiple first reinforcing bars 15 are arranged at intervals from one another in a second transverse direction Y. The first reinforcing bars 15 extend to each end of the concrete 12 in the first transverse direction X. The first reinforcing bars 15 transmit tensile force between the ends of the concrete 12 in the first transverse direction X. Each of the second reinforcing bars 16, 17 extends along the second intersecting direction Y. The second reinforcing bar 16 is disposed above the second reinforcing bar 17. The second reinforcing bars 16, 17 are disposed side by side at intervals in the thickness direction Z. The second reinforcing bars 16, 17 extend to each end of the concrete 12 in the second intersecting direction Y. The second reinforcing bars 16, 17 transmit the tensile force between the ends of the concrete 12 (floor portion 10) in the second intersecting direction Y. As shown in FIG. 3, the second reinforcing bars 16, 17 are joined to each other by a first connecting member 19. The first connecting member 19 extends along the second intersecting direction Y and has a zigzag shape that is alternately folded in the thickness direction Z. The plurality of first reinforcing bars 15 are joined to the plurality of second reinforcing bars 16 by welding, wire or the like.

[0023] The second reinforcing bars 16 are joined to one another by a plurality of second connecting members 20. Each second connecting member 20 extends along the first intersecting direction X and has a zigzag shape that is alternately folded in the thickness direction Z. In each second connecting member 20, peaks and valleys are alternately arranged in the first intersecting direction X. A second reinforcing bar 16 is joined to the upper end of the peak of the second connecting member 20.

[0024] As described above, the reinforcing bars 13 are integrated into a block shape as a whole. The main reinforcement direction W in which the second reinforcing bars 16, 17 extend is the second intersecting direction Y (see FIG. 1). Within the floor section 10, the integrated reinforcing bars 13 may be arranged side by side in the first intersecting direction X and the second intersecting direction Y. For example, in this case, the second reinforcing bars 16 of the reinforcing bars 13 adjacent to each other in the second intersecting direction Y are connected to each other by a joint section (mechanical joint). The joint section joins the pair of second reinforcing bars 16 to each other by clamping the ends of the pair of second reinforcing bars 16 adjacent to each other in the second intersecting direction Y.

[0025] The reinforcing bars 13 are embedded in the concrete 12 . In this embodiment, it is preferable that the ratio of the cross-sectional area of ​​the second reinforcing bars 16, 17 to the cross-sectional area of ​​the concrete 12 in a cross section perpendicular to the second intersecting direction Y is greater than the ratio of the cross-sectional area of ​​the first reinforcing bar 15 to the cross-sectional area of ​​the concrete 12 in a cross section perpendicular to the first intersecting direction X. There is no limit to the number of first reinforcing bars 15 and second reinforcing bars 16, 17 that reinforcing bar 13 has, and there may be just one of each. The floor 10 may be a composite slab having rebar 13 , a deck plate 11 and concrete 12 .

[0026] As shown in FIG. 1, the plurality of fire-resistant coated beams 25 include a pair of first fire-resistant coated beams 26 and a pair of second fire-resistant coated beams 27. For example, the fire-resistant coated beams 26, 27 are H-shaped steel beams with a fire-resistant coating. The fire-resistant coating is made of a heat insulating material such as rock wool or glass wool. In this case, the fire-resistant coating is applied to the H-shaped steel beams by a spraying method.

[0027] For example, the thickness of the fireproof coating such as rock wool on the fireproof coated beams 26, 27 is set in accordance with the "Guidelines for Construction Quality Control of Sprayed Rockwool-Coated Fireproof Structures (Spraying Division of the Rockwool Industry Association)." If one-hour fire resistance is required for the fireproof coated beams 26, 27, the thickness of the fireproof coating shall be 25 mm. Similarly, if two-hour fire resistance is required for the fireproof coated beams 26, 27, the thickness of the fireproof coating shall be 45 mm. If three-hour fire resistance is required for the fireproof coated beams 26, 27, the thickness of the fireproof coating shall be 60 mm. In this specification, a beam or column with a fire-resistant coating means, for example, a beam or column with a fire-resistant coating of this specification.

[0028] The fireproof coating may be applied to the H-shaped steel by a wrapping method or a formed plate method. The fireproof coated beams 26, 27 may be made of reinforced concrete (RC) or steel reinforced concrete (SRC). The pair of first fire-resistant covered beams 26 extend along a first intersecting direction X. The pair of first fire-resistant covered beams 26 are disposed in a second intersecting direction Y at a distance from each other. The pair of second fire-resistant covered beams 27 extend along the second intersecting direction Y. Between the first fire-resistant covered beam 26 and the second fire-resistant covered beam 27, a gap is formed in which the fire-resistant covered column 35 is disposed.

[0029] As shown in Fig. 2, a shear force transmission member 28 such as a stud is fixed to the upper surface of the second fire-resistant covered beam 27. The shear force transmission member 28 penetrates the deck plate 11 and is embedded in the concrete 12. The second fire-resistant covered beam 27 supports the end of the floor portion 10 in the first cross direction X from below the floor portion 10. The second fire-resistant covered beam 27 is fixed (rigidly joined) to the floor portion 10. Although not shown, a shear force transmission member 28 is also fixed to the upper surface of the first fire-resistant covered beam 26. The first fire-resistant covered beam 26 supports the end of the floor portion 10 in the second cross direction Y from below the floor portion 10. The first fire-resistant covered beam 26 is fixed to the floor portion 10. In this way, the fire-resistant coated beams 25 support the periphery of the floor section 10 from below the floor section 10.

[0030] For example, the fire-resistant covered column 35 is an H-shaped steel beam with a fire-resistant covering. As shown in FIG. 1, the multiple fire-resistant covered columns 35 extend along the thickness direction Z. In this embodiment, the multiple fire-resistant covered columns 35 are respectively arranged below the multiple corners 10a of the floor portion 10. Ends of the multiple fire-resistant covered beams 25 are rigidly joined to upper ends (parts) of the multiple fire-resistant covered columns 35. The upper ends of the multiple fire-resistant covered columns 35 and the multiple fire-resistant covered beams 25 are formed into a rectangular ring shape as a whole. In other words, the multiple fire-resistant covered beams 25 and the upper ends of the multiple fire-resistant covered columns 35 surround the region R1. The fire-resistant covered columns may be fire-resistant covered square steel pipes, fire-resistant covered circular steel pipes, concrete-filled steel tubes, reinforced concrete, or steel-reinforced concrete. In this embodiment, the fire-resistant structure 1 includes a plurality of reduced fire-resistant coated beams 40.

[0031] As shown in Fig. 2, in this embodiment, the reduced fire-resistant coating beam 40 is an H-shaped steel 42 with a fire-resistant coating 41 applied thereto. That is, the reduced fire-resistant coating beam 40 has an H-shaped steel 42. The H-shaped steel 42 may be a rolled H-shaped steel or a welded assembled H-shaped steel. However, the reduced fire-resistant coating beam 40 has less fire-resistant coating than the fire-resistant coating beam 25. The multiple reduced fire-resistant covered beams 40 are arranged within the region R1, and both ends thereof are joined to the multiple fire-resistant covered beams 25 by pin joints. For example, the pin joints are formed by fastening a gusset plate welded to the fire-resistant covered beam 25 to the reduced fire-resistant covered beam 40 by a high-strength bolt or the like. Note that both ends of the multiple reduced fire-resistant covered beams 40 may be joined to the fire-resistant covered beam 25 by rigid or semi-rigid joints. The definitions of pin joints, semi-rigid joints, and rigid joints shall conform to the European design standards (Eurocode3 Parts 1-8), in particular. The H-shaped steel 42 has a web 44 and a pair of flanges 45 arranged to sandwich the web 44 therebetween.

[0032] 1, the multiple fire-resistant coated beams 40 each extend in a first intersecting direction X and are spaced apart from one another in a second intersecting direction Y. That is, the multiple fire-resistant coated beams 40 are arranged along the longitudinal direction of the floor portion 10 when viewed in the thickness direction Z. Although not shown, a shear force transmission member 28 is also fixed to the upper surfaces of the multiple reduced fire-resistant coated beams 40. The multiple reduced fire-resistant coated beams 40 support the floor section 10 from below the floor section 10. The multiple reduced fire-resistant coated beams 40 are fixed (rigidly connected) to the floor section 10. In this way, the multiple reduced fire-resistant coated beams 40 support the floor section 10 from below.

[0033] When the thickness of the fire-resistant coating in the fire-resistant coated beam 25 is set in accordance with the "Guidelines for Construction Quality Control of Sprayed Rock Wool Coated Fire-Resistant Structures," the thickness of the fire-resistant coating in the reduced fire-resistant coated beam 40 shall be approximately 1 / 10 to 1 / 2 of the thickness of the fire-resistant coating in the fire-resistant coated beam 25 according to the respective fire resistance performances. The number of reduced fire-resistant coated beams 40 provided in the fire-resistant structure 1 may be one.

[0034] Next, a design method for a fireproof structure 1 according to the present embodiment (hereinafter, simply referred to as a design method) for designing the fireproof structure 1 configured as above will be described. Fig. 4 is a flowchart showing a design method S10 according to an embodiment of the present invention. First, in the structure setting process (step S11 shown in FIG. 4), known structural calculations are performed to set the arrangement of the floor 10, multiple beams 50, and multiple columns 51 in the foundation structure 1A, which is the fireproof structure 1 before the application of fireproof covering, as shown in FIG. 5. The multiple beams 50 support the floor 10 from below. The multiple columns 51 are joined to the multiple beams 50. The upper ends of the multiple columns 51 and the multiple beams 50 are formed into a rectangular ring shape as a whole. In the structural setting process S11, for the third fire resistance specification setting process S17 described later, some of the multiple beams 50 (beams 50B) are set to be arranged along the longitudinal direction of the floor section 10 when viewed in the thickness direction Z. When the structure setting step S11 is completed, the process proceeds to step S13.

[0035] Next, in the first fire resistance specification setting process (step S13), the periphery of the floor section 10 is set to be supported from below by a plurality of fire-resistant coated beams 25, which are beams 50A that are part of a plurality of beams 50 and have a fire-resistant coating applied thereto (see Figure 1). When the first fire resistance specification setting step S13 is completed, the process proceeds to step S15. Next, in a second fire resistance specification setting step (step S15), a fire resistance coating is applied to the multiple columns 51 to set them as multiple fire resistance coated columns 35 (see FIG. 1). When the second fire-resistant specification setting step S15 is completed, the process proceeds to step S17.

[0036] Next, in a third fire resistance specification setting process (step S17), a plurality of reduced fire-resistant coated beams 40, in which fire-resistant coating is applied to beams 50B, which are the remaining parts of the plurality of beams 50, are arranged in the region R1 (see FIG. 1). Furthermore, the ends of the reduced fire-resistant coated beams 40 are joined to the fire-resistant coated beams 25, and the reduced fire-resistant coated beams 40 are set to support the floor section 10 from below. In the third fire resistance specification setting process S17, the reduced fire-resistant coated beams 40 are set to be arranged along the longitudinal direction of the floor section 10 when viewed in the thickness direction Z. When the third fire resistance specification setting step S17 is completed, all steps of the design method S10 are completed, and the fire resistance structure 1 is designed. It is not necessary to provide a fire-resistant coating to the reduced fire-resistant coating beam 40 of the fire-resistant structure 1. In this case, in the third fire resistance specification setting step S17, the remaining beams 50B of the beams 50 are disposed in the region R1.

[0037] Next, a description will be given of a construction method for a fireproof structure (hereinafter, simply referred to as a construction method) of this embodiment for constructing the fireproof structure 1. Fig. 6 is a flowchart showing a construction method S20 in one embodiment of the present invention. First, in the column and beam construction step (step S21 shown in FIG. 6), a foundation structure 1A including a floor section 10, a plurality of beams 50, and a plurality of columns 51 is constructed. The plurality of beams 50 support the floor section 10 from below. The plurality of columns 51 are joined to the plurality of beams 50. When the column and beam construction process S21 is completed, the process proceeds to step S23.

[0038] Next, in a first covering step (step S23), the periphery of floor section 10 is supported from below by a plurality of fire-resistant coated beams 25 formed by applying fire-resistant coating to beams 50A, which are part of a plurality of beams 50. When the first covering step S23 is completed, the process proceeds to step S25. Next, in the second covering step (step S25), a fire-resistant covering is applied to the multiple columns 51 to form multiple fire-resistant covered columns 35. When the second covering step S25 is completed, the process proceeds to step S27.

[0039] Next, in a third covering step (step S27), a plurality of reduced fire-resistant coated beams 40, in which fire-resistant coating is applied to beams 50B, which are the remaining parts of the plurality of beams 50, are arranged in region R1. Furthermore, the ends of the reduced fire-resistant coated beams 40 are joined to the fire-resistant coated beams 25 to support the floor section 10 from below. In the third covering step S27, the plurality of reduced fire-resistant coated beams 40 are arranged along the longitudinal direction of the floor section 10 when viewed in the thickness direction Z. When the third covering step S27 is completed, all steps of the construction method S20 are completed, and the fireproof structure 1 is constructed. It is not necessary to provide a fireproof coating to the reduced fireproof coating beams 40 of the fireproof structure 1. In this case, in the third coating step S27, the remaining beams 50B of the beams 50 are disposed within the region R1.

[0040] Here, a schematic explanation will be given of how the floor section 10 and the like bend due to the membrane effect before and after a fire. Fig. 7 shows an exploded perspective view of the fireproof structure 1 in normal times when no fire has broken out. Note that Fig. 7 and Fig. 8, which will be described later, show the fireproof structure 1 in a simplified form. Under normal conditions as shown in FIG. 7, a downward external force F1 acts on the floor portion 10, the reduced fire-resistant coating beams 40, etc. due to gravity, static load, etc. acting on the floor portion 10, the reduced fire-resistant coating beams 40, etc. On the other hand, in the event of a fire, as shown in Fig. 8, the center of the floor section 10 in plan view bends downward to become convex. However, due to the so-called membrane effect, the periphery of the floor section 10 is supported by the upper ends of the multiple fire-resistant covered beams 25 and multiple fire-resistant covered columns 35, which are formed in a ring shape as a whole. The first reinforcing bars 15 that stretch as the floor section 10 bends transmit the tensile force F2 in the first intersecting direction X. The second reinforcing bars 16, 17 that stretch as the floor section 10 bends transmit the tensile force F3 in the second intersecting direction Y. In other words, the floor section 10 resists gravity and other forces acting on the floor section 10 with the tensile forces F2, F3. Therefore, the central portion of the floor portion 10 is supported in the first intersecting direction X and the second intersecting direction Y by the multiple fire-resistant covered beams 25, the upper ends of the multiple fire-resistant covered columns 35, the first reinforcing bars 15, and the second reinforcing bars 16, 17, respectively.

[0041] At this time, a tension region R5 and a compression region R6 are formed in the bed portion 10. The compression region R6 is shown hatched in Fig. 8. In the tension region R5, the bed portion 10 is tensioned along the bent upper surface. In the compression region R6, the bed portion 10 is compressed along the bent upper surface. The tension region R5 is formed in the center in a plan view of the bed portion 10. The compression region R6 is formed around the tension region R5. The membrane effect that occurs in the fire-resistant structure 1 during a fire is the effect of the reinforcing bars 13 resisting tensile forces F2 and F3.

[0042] As described above, in the design method S10 of this embodiment, in the structure setting step S11, the arrangement of the floor part 10, the beams 50, and the columns 51 is set. Next, in the first fire resistance specification setting step S13, the periphery of the floor part 10 is set to be supported from below by the fire-resistant coated beams 25 in which a part of the beams 50 is covered with a fire-resistant coating. Next, in the second fire resistance specification setting step S15, the columns 51 are covered with a fire-resistant coating and set as the fire-resistant coated columns 35. Next, in the third fire resistance specification setting step S17, the reduced fire-resistant coated beams 40 in which the remaining parts of the beams 50 are covered with a fire-resistant coating are placed in the region R1 surrounded by the fire-resistant coated beams 25 and the fire-resistant coated columns 35, and the ends of the reduced fire-resistant coated beams 40 are joined to the fire-resistant coated beams 25 to support the floor part 10 from below. In the third fire resistance specification setting process S17, the reduced fire resistance coated beam 40 is set so as to be arranged along the longitudinal direction of the floor portion 10 when viewed in the thickness direction Z. By carrying out the above steps, the fireproof structure 1 is designed.

[0043] In the fireproof structure 1 designed as above, the periphery of the floor portion 10 is supported from below by the upper ends of the plurality of fireproof-coated beams 25 and the plurality of fireproof-coated columns 35 formed in an annular shape, which can maintain a certain rigidity and strength even in the event of a fire. The reinforcing bars 13 provided in the floor portion 10 transmit the tensile force between the ends of the floor portion 10 in the first intersecting direction X and the tensile force between the ends of the floor portion 10 in the second intersecting direction Y. In the event of a fire, the floor portion 10 is deflected so that the center of the floor portion 10 in a plan view is convex downward due to gravity acting on the floor portion 10. However, due to the membrane effect, the periphery of the floor portion 10 is supported by the upper ends of the plurality of fireproof-coated beams 25 and the plurality of fireproof-coated columns 35. The reinforcing bars 13 extended by the deflection of the floor portion 10 transmit the tensile force in the first intersecting direction X and the second intersecting direction Y, respectively, thereby supporting the center of the floor portion 10. Therefore, the fireproof performance of the fireproof structure 1 can be maintained at the same level as in the past.

[0044] Furthermore, the multiple fire-resistant coated beams 40 are arranged along the longitudinal direction of the floor portion 10 when viewed in the thickness direction Z. Therefore, compared to when the fire-resistant coated beams 40 are arranged along the lateral direction of the floor portion 10 when viewed in the thickness direction Z, the number of fire-resistant coated beams 40 arranged in the region R1 surrounded by the upper ends of the multiple fire-resistant coated beams 25 and the multiple fire-resistant coated columns 35 formed in an annular shape can be reduced. Each fire-resistant coated beam 40 is joined to the fire-resistant coated beam 25 at two points at both ends. Therefore, the number of points where the fire-resistant coated beams 40 are joined to the fire-resistant coated beams 25 can be reduced.

[0045] Fig. 9 shows a plan view of the fire-resistant structure 1. In Fig. 9, the floor portion 10 is not shown. 9, the fire-resistant structure 2 of the comparative example is shown overlapping. The reduced fire-resistant coated beam 55 of the fire-resistant structure 2 is arranged along the second intersecting direction Y, which is the short-side direction of the floor section 10 when viewed in the thickness direction Z. For example, the reduced fire-resistant coated beam 55 has a different length and cross-sectional dimensions from the reduced fire-resistant coated beam 40. The tension region R5 and compression region R6 are shown in Fig. 9. The following (1) to (3) are assumed as possible modes of collapse of the membrane structure caused by the bed portion 10. (1) Fracture of steel bar 13. (2) Slippage of the joint of reinforcing bar 13 (the joint slips relative to the second reinforcing bar 16). (3) Destruction of Concrete 12. The length of one reduced fire-resistant coated beam 40 of the fire-resistant structure 1 arranged in the tensile region R5 is longer than the length of one reduced fire-resistant coated beam 55 of the fire-resistant structure 2 arranged in the tensile region R5. Since the reduced fire-resistant coated beams 40, 55 are set continuously between a plurality of fire-resistant coated beams 25, the total width of the joint portion calculated by multiplying the length of the reduced fire-resistant coated beams 40, 55 arranged in the tensile region R5 by the number of the reduced fire-resistant coated beams 40, 55 is smaller in the fire-resistant structure 1 than in the fire-resistant structure 2. Therefore, it is possible to suppress the occurrence of slippage of the joint portion of the reinforcing bar 13 in (2).

[0046] The reduced fire-resistant coating beam 40 has an H-shaped steel 42. Since the H-shaped steel 42 is widely used as a beam, the reduced fire-resistant coating beam 40 can be designed (constructed) at low cost. The floor section 10 is a reinforced concrete slab. Since reinforced concrete slabs are widely used as floor sections, the floor section 10 can be designed (constructed) at low cost.

[0047] The reinforcing bars 13 include a plurality of first reinforcing bars 15 and a plurality of second reinforcing bars 16, 17. Therefore, with a simple configuration including a plurality of first reinforcing bars 15 and a plurality of second reinforcing bars 16, 17, the tensile force F2 between the ends of the floor portion 10 in the first intersecting direction X and the tensile force F3 between the ends of the floor portion 10 in the second intersecting direction Y can be transmitted. In the floor section 10, as the aspect ratio of the floor section 10 increases, it becomes difficult for the membrane effect to improve the strength of the floor section 10. The behavior of the floor section 10 in the short direction becomes dominant. The ratio of the cross-sectional area of ​​the second reinforcing bars 16, 17 to the cross-sectional area of ​​the concrete 12 in the cross section perpendicular to the second intersecting direction Y is greater than the ratio of the cross-sectional area of ​​the first reinforcing bar 15 to the cross-sectional area of ​​the concrete 12 in the cross section perpendicular to the first intersecting direction X. This makes it possible to keep the deflection of the floor section 10 small and to extend the fire resistance time of the fireproof structure 1.

[0048] The fire-resistant coated beam 25 is an H-shaped steel beam with a fire-resistant coating. Since the H-shaped steel beam is widely used as a beam, the fire-resistant coated beam 25 can be designed at low cost. The fire-resistant covered column 35 is an H-shaped steel with a fire-resistant coating. Since the H-shaped steel is widely used as a column, the fire-resistant covered column 35 can be designed inexpensively. The fireproof coating is applied to the H-beam by the wrapping method, which is widely used to apply fireproof coating to H-beams and other structures, and therefore allows the coating to be applied inexpensively.

[0049] In the construction method S20 of this embodiment, in the column-beam construction step S21, the floor section 10, the beams 50, and the columns 51 are constructed. Next, in the first covering step S23, the periphery of the floor section 10 is supported from below by the fire-resistant coated beams 25 in which a part of the beams 50 is covered with a fire-resistant coating. Next, in the second covering step S25, the columns 51 are covered with a fire-resistant coating to form the fire-resistant coated columns 35. Next, in the third covering step S27, the reduced fire-resistant coated beams 40 in which the remaining parts of the beams 50 are covered with a fire-resistant coating are arranged in the region R1 surrounded by the fire-resistant coated beams 25 and the fire-resistant coated columns 35, and the ends of the reduced fire-resistant coated beams 40 are joined to the fire-resistant coated beams 25 to support the floor section 10 from below. In the third covering step S27, the reduced fire-resistant coated beams 40 are arranged along the longitudinal direction of the floor section 10 when viewed in the thickness direction Z. By carrying out the above steps, the fireproof structure 1 is constructed.

[0050] In the fireproof structure 1 constructed as described above, the periphery of the floor portion 10 is supported from below by the upper ends of the plurality of fireproof-coated beams 25 and the plurality of fireproof-coated columns 35 formed in an annular shape, which can maintain a certain rigidity and strength even in the event of a fire. The reinforcing bars 13 provided in the floor portion 10 transmit the tensile force between the ends of the floor portion 10 in the first intersecting direction X and the tensile force between the ends of the floor portion 10 in the second intersecting direction Y. In the event of a fire, the floor portion 10 is deflected so that the center of the floor portion 10 in a plan view is convex downward due to gravity acting on the floor portion 10. However, due to the membrane effect, the periphery of the floor portion 10 is supported by the upper ends of the plurality of fireproof-coated beams 25 and the plurality of fireproof-coated columns 35. The reinforcing bars 13 extended by the deflection of the floor portion 10 transmit the tensile force in the first intersecting direction X and the second intersecting direction Y, respectively, thereby supporting the center of the floor portion 10. Therefore, the fireproof performance of the fireproof structure 1 can be maintained at the same level as in the past.

[0051] Furthermore, the multiple fire-resistant coated beams 40 are arranged along the longitudinal direction of the floor portion 10 when viewed in the thickness direction Z. Therefore, compared to when the fire-resistant coated beams 40 are arranged along the lateral direction of the floor portion 10 when viewed in the thickness direction Z, the number of fire-resistant coated beams 40 arranged in the region R1 surrounded by the upper ends of the multiple fire-resistant coated beams 25 and the multiple fire-resistant coated columns 35 formed in an annular shape can be reduced. Each fire-resistant coated beam 40 is joined to the fire-resistant coated beam 25 at two points at both ends. Therefore, the number of points where the fire-resistant coated beams 40 are joined to the fire-resistant coated beams 25 can be reduced.

[0052] In the fireproof structure 1 of this embodiment, the periphery of the floor portion 10 is supported from below by the upper ends of the plurality of fireproof-coated beams 25 and the plurality of fireproof-coated columns 35 formed in an annular shape, which can maintain a certain rigidity and strength even in the event of a fire. The reinforcing bars 13 provided in the floor portion 10 transmit the tensile force between the ends of the floor portion 10 in the first intersecting direction X and the tensile force between the ends of the floor portion 10 in the second intersecting direction Y. In the event of a fire, the floor portion 10 is deflected so that the center of the floor portion 10 in a plan view is convex downward due to gravity acting on the floor portion 10. However, due to the membrane effect, the periphery of the floor portion 10 is supported by the upper ends of the plurality of fireproof-coated beams 25 and the plurality of fireproof-coated columns 35. The reinforcing bars 13 extended by the deflection of the floor portion 10 transmit the tensile force in the first intersecting direction X and the second intersecting direction Y, respectively, thereby supporting the center of the floor portion 10. Therefore, the fireproof performance of the fireproof structure 1 can be maintained at the same level as in the past.

[0053] Furthermore, the multiple fire-resistant coated beams 40 are arranged along the longitudinal direction of the floor portion 10 when viewed in the thickness direction Z. Therefore, compared to when the fire-resistant coated beams 40 are arranged along the lateral direction of the floor portion 10 when viewed in the thickness direction Z, the number of fire-resistant coated beams 40 arranged in the region R1 surrounded by the upper ends of the multiple fire-resistant coated beams 25 and the multiple fire-resistant coated columns 35 formed in an annular shape can be reduced. Each fire-resistant coated beam 40 is joined to the fire-resistant coated beam 25 at two points at both ends. Therefore, the number of points where the fire-resistant coated beams 40 are joined to the fire-resistant coated beams 25 can be reduced.

[0054] (Simulation results) Here, the results of a simulation of the fire resistance of the fire-resistant structures of the examples and the comparative examples will be described.

[0055] (1. Examination of the direction of extension of reduced fire-resistant covered beams 1) Figure 10 shows an outline of an analytical model of the fireproof structure 1B of the embodiment. In Figure 10 and Figure 11 described later, beams with fireproof covering applied without reduction are shown by solid lines, and beams with reduced fireproof covering are shown by dotted lines. Note that the floor section 10 is not shown in Figures 10 and 11. The cross-sectional dimensions of the H-shaped steel of the fire-resistant covered beams 26, 27 were H-1000 × 400 × 19 × 28. As shown in Fig. 10, the fire-resistant covered beams 26, 27 were allowed to rotate around the first intersecting direction X, the second intersecting direction Y, and the thickness direction Z with respect to the upper end of each fire-resistant covered column 35. The fire-resistant covered beams 26, 27 are fixed in the first intersecting direction X, the second intersecting direction Y, and the thickness direction Z relative to a fire-resistant covered column 35A, which is one of the plurality of fire-resistant covered columns 35. The fire-resistant covered beams 26, 27 are movable in the first intersecting direction X, the second intersecting direction Y, and the thickness direction Z relative to a fire-resistant covered column 35B other than the fire-resistant covered column 35A among the plurality of fire-resistant covered columns 35.

[0056] The length L5 of the first fireproof covering beam 26 (the length in the longitudinal direction of the floor portion 10) was set to 19,200 mm. The length L6 of the second fireproof covering beam 27 (the length in the lateral direction of the floor portion 10) was set to 7,200 mm. The reduced fire-resistant covered beam 40A is a beam that is not covered with any fire-resistant covering, unlike the reduced fire-resistant covered beam 40. The cross-sectional dimensions of the H-shaped steel 42 of the reduced fire-resistant covered beam 40A are H-1000×400×19×28, which are the same as the cross-sectional dimensions of the H-shaped steel of the fire-resistant covered beams 26 and 27. The yield strength σ of the H-shaped steel 42 at room temperature y is 325N / mm 2 It was decided. Description of the specifications of the floor 10 used in the fire-resistant structure 1B will be omitted. In FIG. 10, the direction in which the second reinforcing bars 16, 17 extend (second intersecting direction Y) is shown as the main reinforcement direction W. The thickness of the floor portion 10 was 140 mm. The second reinforcing bars 16, 17 were D13@200. The first reinforcing bar 15 was D10@150. The thickness of the fireproof coating of the fireproof coating beams 26, 27 was 45 mm.

[0057] On the other hand, the fireproof structure 2 of the comparative example shown in FIG. 11 has a plurality of reduced fireproof coating beams 55 instead of the plurality of reduced fireproof coating beams 40A of the fireproof structure 1B of the embodiment. The H-shaped steel of the reduced fireproof coating beam 55 is a rolled H-shaped steel 56. The cross-sectional dimensions of the rolled H-shaped steel 56 are H-500×200×10×16. The yield strength σ of the rolled H-shaped steel 56 at room temperature is y is 235N / mm 2 In the fire-resistant structure 2, the main reinforcement direction W was set to the first intersecting direction X.

[0058] It was assumed that the fireproof structures 1B and 2 were heated for 120 minutes (2 hours) based on the standard heating curve specified in ISO 834-11:2014. Generally, the length of beams, columns, and other components increases as the temperature increases. A simulation was carried out to determine the relationship between the temperature and time of the components when they were heated based on the standard heating curve. Then, based on the previously determined relationship, the deflection of the components due to thermal expansion, strength, and reduction in rigidity over time from the start of combustion (heating) was determined. The deflection is the deflection at the center P1 (see Figures 10 and 11) of the floor 10 in a plan view.

[0059] The total strain is represented by the sum of the mechanical strain and the thermal strain. The condition for terminating the simulation is, for example, when the mechanical strain at the ends of the H-shaped steels 42, 56 exceeds a threshold value such as 20%. The reason for determining the condition for terminating the simulation in this manner is that the strain at the ends of the H-shaped steels 42, 56 is the largest.

[0060] An example of the state of deflection in the simulation results for fireproof structure 1B is shown in Figure 12. The shape of fireproof structure 1B before heating is shown by the two-dot chain line. It was found that fireproof structure 1B was able to support the vertical load even 120 minutes after the start of combustion. An example of the state of deflection in the simulation results of the fire-resistant structure 2 is shown in Fig. 13. The simulation was terminated 94 minutes after the start of heating because the mechanical strain at the end of the reduced fire-resistant coated beam 55 located at the center in the first cross direction X exceeded a threshold value.

[0061] (2. Examination of the extension direction of reduced fire-resistant covered beams 2) As shown in Table 1, parametric studies were conducted for Cases 1 to 6 in which the length L5 of the first fire-resistant covered beam 26 of the fire-resistant structures 1B and 2 was changed to 19,200 mm, 14,400 mm, and 9,600 mm.

[0062] [Table 1]

[0063] The results of the simulation in (1.) correspond to Case 1 and Case 2. Figure 14 shows the results of determining the change in deflection at center P1 versus the burning time for cases 1 to 6. In Figure 14, the horizontal axis represents the burning time (minutes) and the vertical axis represents the deflection (mm). Lines L11 to L16 represent the results for cases 1 to 6, respectively. It was found that for any length L5, the fireproof structure 1B of the example was able to support a vertical load for a longer combustion time than the fireproof structure 2 of the comparative example. In addition, in the cases of Case 5 and Case 6, where the length L5 is 9,600 mm, it was found that the deflection of the fire-resistant structure 1B of the embodiment (see line L15) was smaller than that of the fire-resistant structure 2 of the comparative example (see line L16) at the same combustion time. As described above, it was found that the fireproof structures 1 of the examples (cases 1, 3, and 5) were able to maintain their fire resistance performance compared to the fireproof structures 2 of the comparative examples (cases 2, 4, and 6).

[0064] (3. Consideration of fire resistance time) The analysis was performed under the same conditions as above for the simulation end condition. It was assumed that the fire-resistant structures 1B and 2 were heated for 8 hours based on the standard heating curve specified in ISO 834-11:2014. The time until the simulation ends corresponds to the fire resistance time of the fire-resistant structures 1B and 2. The simulation results are shown in Fig. 15. In Fig. 15, the horizontal axis represents the length L5 of the first fire-resistant covered beam 26, and the vertical axis represents the time (minutes) until the simulation is completed. The dotted line L21 represents the results for the fireproof structure 1B of the embodiment in cases 1, 3 and 5, and the solid line L22 represents the results for the fireproof structure 2 of the comparative example in cases 2, 4 and 6.

[0065] As shown in Fig. 15, the lines L21 and L22 intersect when the length L5 is 11,000 mm (11 m). It was found that when the length L5 exceeds 11,000 mm, the fire resistance time of the fireproof structure 1B of the embodiment exceeds the fire resistance time of the fireproof structure 2 of the comparative example. The aspect ratio of the floor portion 10 at this time is 1.52 from the formula (11,000 / 7,200). In other words, it was found that when the aspect ratio of the floor portion 10 exceeds 1.52, the fire resistance time of the fireproof structure 1B of the embodiment exceeds the fire resistance time of the fireproof structure 2 of the comparative example. When the length L5 is 14,400 m or more, the fire resistance time of the fireproof structure 1B of the embodiment is about three times that of the fireproof structure 2 of the comparative example, and it was found that the fire resistance performance is further improved. In this case, the aspect ratio of the floor portion 10 is 2.0 from the formula (14,400 / 7,200).

[0066] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and changes, combinations, deletions, etc. of the configuration are also included within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0067] 1 Fireproof structures 10 Floor 11 Deck plate 12. Concrete 13 Reinforcement bars (tensile force transmission members) 15 First Reinforcement Bar 16,17 Second rebar 25 Fireproof coated beam 35 Fireproof Coated Column 40 Reduced fire resistance coated beam 41 Fireproof coating 42 H-shaped steel 50 beams 51 Pillars R1 area S10 Design method (Design method for fire-resistant structures) S11 Structure setting process S13 First fire resistance specification setting process S15 Second fire resistance specification setting process S17 3rd fire resistance specification setting process S20 Construction method (construction method for fire-resistant structures) S21 Column and beam construction process S23 First coating process S25 Second coating process S27 3rd coating process X 1st cross direction Y Second cross direction

Claims

1. A floor portion having a rectangular shape when viewed in a thickness direction, the floor portion having a tensile force transmission member provided in concrete; A plurality of fire-resistant coated beams that are provided with a fire-resistant coating and support the periphery of the floor section from below; A plurality of fire-resistant covered columns each having a fire-resistant coating and joined to ends of the plurality of fire-resistant covered beams, so that a portion of the fire-resistant covered columns and the plurality of fire-resistant covered beams as a whole form a ring; a reduced fire-resistant covered beam having a reduced fire-resistant covering compared to the fire-resistant covered beam, arranged within an area surrounded by the plurality of fire-resistant covered beams and the plurality of fire-resistant covered columns, and having an end portion joined to the plurality of fire-resistant covered beams to support the floor section from below; Equipped with When directions intersecting each other in the plane of the floor portion are defined as a first intersecting direction and a second intersecting direction, A method for designing a fire-resistant structure, in which the tensile force transmission member transmits a tensile force between ends of the floor portion in the first intersecting direction and a tensile force between ends of the floor portion in the second intersecting direction, a structural setting process for setting the arrangement of the floor portion, a plurality of beams supporting the floor portion from below, and a plurality of columns joined to the plurality of beams by performing structural calculations; A first fire resistance specification setting process for setting the periphery of the floor section to be supported from below by the plurality of fire-resistant coated beams in which a fire-resistant coating is applied to a portion of the plurality of beams; A second fire resistance specification setting step of applying fire resistance coating to the plurality of columns and setting the fire resistance coating to the plurality of columns; A third fire resistance specification setting process in which the reduced fire resistance coated beam, which is the remaining part of the plurality of beams, or the reduced fire resistance coated beam in which the remaining part of the plurality of beams is provided with a fire resistance coating, is placed within the region, and the end of the reduced fire resistance coated beam is joined to the fire resistance coated beam to support the floor section from below; Do the following: A design method for a fire-resistant structure, in which the third fire resistance specification setting process sets the reduced fire resistance coated beam so as to be arranged along the longitudinal direction of the floor section when viewed in the thickness direction.

2. The method for designing a fire-resistant structure according to claim 1 , wherein the reduced fire-resistant coating beam comprises an H-shaped steel.

3. 3. The design method for a fire-resistant structure according to claim 1 or 2, wherein, when the floor portion is viewed in the thickness direction, a ratio of the length in the longitudinal direction to the length in the lateral direction exceeds 1.

52.

4. The design method for a fire-resistant structure according to claim 1 , wherein the floor portion is a composite slab or a reinforced concrete slab.

5. The tensile force transmission member is A first reinforcing bar extending along the first intersecting direction and transmitting a tensile force between ends of the floor section in the first intersecting direction; 5. The design method for a fire-resistant structure according to claim 1, further comprising: a second reinforcing bar extending along the second intersecting direction and transmitting a tensile force between ends of the floor section in the second intersecting direction.

6. The first intersecting direction is a longitudinal direction of the floor portion when viewed in the thickness direction, The second intersecting direction is a short-side direction of the floor portion when viewed in the thickness direction, 6. A design method for a fire-resistant structure as described in claim 5, wherein a ratio of a cross-sectional area of ​​the second reinforcing bar to a cross-sectional area of ​​the concrete in a cross section perpendicular to the short direction is greater than a ratio of a cross-sectional area of ​​the first reinforcing bar to a cross-sectional area of ​​the concrete in a cross section perpendicular to the long direction.

7. The method for designing a fire-resistant structure according to claim 1 , wherein the fire-resistant coated beam is an H-shaped steel beam, a reinforced concrete beam, or a steel-reinforced concrete beam to which the fire-resistant coating is applied.

8. 8. The design method for a fire-resistant structure according to claim 1, wherein the fire-resistant coated column is an H-shaped steel column coated with the fire-resistant coating, a square steel pipe coated with the fire-resistant coating, a circular steel pipe coated with the fire-resistant coating, a concrete-filled steel pipe structure, a reinforced concrete structure, or a steel-reinforced concrete structure.

9. The method for designing a fire-resistant structure according to claim 1 , wherein the fire-resistant coating is applied by a spraying method, a molded plate method, or a wrapping method.

10. 10. The design method for a fire-resistant structure according to claim 1, wherein the longitudinal length of the floor section when viewed in the thickness direction exceeds 11 m.

11. A floor portion having a rectangular shape when viewed in a thickness direction, the floor portion having a tensile force transmission member provided in concrete; A plurality of fire-resistant coated beams that are provided with a fire-resistant coating and support the periphery of the floor section from below; A plurality of fire-resistant covered columns each having a fire-resistant coating and joined to ends of the plurality of fire-resistant covered beams, so that a portion of the fire-resistant covered columns and the plurality of fire-resistant covered beams as a whole form a ring; a reduced fire-resistant covered beam having a reduced fire-resistant covering compared to the fire-resistant covered beam, arranged within an area surrounded by the plurality of fire-resistant covered beams and the plurality of fire-resistant covered columns, and having an end portion joined to the plurality of fire-resistant covered beams to support the floor section from below; Equipped with When directions intersecting each other in the plane of the floor portion are defined as a first intersecting direction and a second intersecting direction, A method of constructing a fire-resistant structure, in which the tensile force transmission member transmits a tensile force between ends of the floor portion in the first intersecting direction and a tensile force between ends of the floor portion in the second intersecting direction, A column-beam construction process for constructing the floor portion, a plurality of beams supporting the floor portion from below, and a plurality of columns joined to the plurality of beams; A first covering step of supporting the periphery of the floor portion from below with an annular fire-resistant coated beam having a fire-resistant coating applied to a portion of the plurality of beams; A second coating step of applying a fire-resistant coating to the plurality of columns to obtain the plurality of fire-resistant coated columns; A third covering step of placing the reduced fire-resistant coated beam, which is the remaining part of the plurality of beams, or the reduced fire-resistant coated beam obtained by applying a fire-resistant coating to the remaining part of the plurality of beams, within the region, and joining the end of the reduced fire-resistant coated beam to the fire-resistant coated beam to support the floor section from below; Do the following: A construction method for a fire-resistant structure, in which the third covering process involves arranging the reduced fire-resistant covered beam along the longitudinal direction of the floor portion when viewed in the thickness direction.

12. A floor portion having a rectangular shape when viewed in a thickness direction, the floor portion having a tensile force transmission member provided in concrete; A plurality of fire-resistant coated beams that are provided with a fire-resistant coating and support the periphery of the floor section from below; A plurality of fire-resistant covered columns each having a fire-resistant coating and joined to ends of the plurality of fire-resistant covered beams, so that a portion of the fire-resistant covered columns and the plurality of fire-resistant covered beams as a whole form a ring; a reduced fire-resistant covered beam having a reduced fire-resistant covering compared to the fire-resistant covered beam, arranged within an area surrounded by the plurality of fire-resistant covered beams and the plurality of fire-resistant covered columns, and having an end portion joined to the plurality of fire-resistant covered beams to support the floor section from below; Equipped with When directions intersecting each other in the plane of the floor portion are defined as a first intersecting direction and a second intersecting direction, The tensile force transmission member transmits a tensile force between the ends of the floor portion in the first intersecting direction and a tensile force between the ends of the floor portion in the second intersecting direction, A fire-resistant structure, wherein the reduced fire-resistant coated beam is arranged along the longitudinal direction of the floor portion when viewed in the thickness direction.

Images