Refractory structures

Abstract

To provide a fireproof structure in which versatility of arrangement of a reduced-fire resistant covered beam is increased and deflection of a floor portion during fire is suppressed.SOLUTION: A fireproof structure includes: a floor portion 10 in which a tensile force transmission members is provided inside concrete; a plurality of fire-resistant beams 25 having predetermined fire resistance; a plurality of fire resistance pillars 40 which have predetermined fire resistance, are joined to a plurality of fire-resistant beams, and in which at least a part of the entire fire-resistant beams and a plurality of fire-resistant beams are located in a ring-shaped refractory ring 43 and which supports the floor from below all around; and a plurality of reduced fire-resistant beams 45 which have no predetermined fire resistance, and are arranged inside the refractory ring. Out of the plurality of reduced fire-resistant beams, the material axis direction of the first reduced fire-resistant beams 46A-46C and the material axis direction of the second reduced fire-resistant beams 47A-47D, which are the other reduced fire-resistant beams, intersect each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, fire-resistant structures configured to maintain constant rigidity and yield strength even during a fire are known (see, for example, Patent Document 1). A slab (floor portion) of the fire-resistant structure is supported by girders and steel secondary beams (reduced fire-resistance performance beams). The girders are made of reinforced concrete and bridged between columns. The steel secondary beams are bridged between the girders. Four sides of the slab are rigidly joined to the girders. The steel secondary beams are formed of H-shaped steel beams that are not entirely subjected to fire-resistant coating treatment. The steel secondary beams are integrated with the slab by a plurality of studs welded to the upper flange of the steel secondary beams. [Prior Art Documents] [Patent Documents]

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

[0004] There are cases where pipes for water supply, air conditioning, etc. are arranged between a plurality of steel secondary beams. However, the plurality of steel secondary beams in Patent Document 1 are arranged parallel to each other. For this reason, when pipes are arranged so as to avoid the plurality of steel secondary beams, the degree of freedom in pipe arrangement is limited, and the degree of design freedom is restricted when providing an opening for installing a construction elevator or an opening for grounding a permanent connecting stairway. Furthermore, during a fire, steel secondary beams cannot maintain constant rigidity and yield strength, so the deflection of the slab supported by the steel secondary beams increases.

[0005] This invention has been made in view of the above problems, and aims to provide a fire-resistant structure that increases the degree of freedom in the arrangement of fire-reducing beams and suppresses the deflection of the floor during a fire. [Means for solving the problem]

[0006] To solve the aforementioned problems, this invention proposes the following means. (1) One aspect of the present invention is a fire-resistant structure comprising: a floor section in which a tensile force transmission member is provided in concrete; a plurality of fire-resistant beams having a predetermined fire resistance performance; a plurality of fire-resistant columns having the predetermined fire resistance performance and joined to the plurality of fire-resistant beams, with an annular fire-resistant annular body formed by a part of itself and the entire plurality of fire-resistant beams supporting the floor section from below around its entire circumference; and a plurality of fire-reducing beams not having the predetermined fire resistance performance and arranged within the fire-resistant annular body to support the floor section from below, wherein when the directions in which the floor section intersects with each other in the plane of the floor section are defined as the first intersecting direction and the 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 material axis direction of one of the plurality of fire-reducing beams, the first fire-reducing beam, intersects with the material axis direction of another of the plurality of fire-reducing beams, the second fire-reducing beam.

[0007] In this invention, under normal conditions (at room temperature), the material axis direction of the first fire-resistant beam and the material axis direction of the second fire-resistant beam intersect, thereby increasing the degree of freedom in arranging the fire-resistant beams compared to the case where multiple fire-resistant beams are parallel to each other. On the other hand, the floor is supported from below around its entire perimeter by a fire-resistant annular body that maintains a certain level of rigidity and strength even during a fire. Tensile force transmission members provided within the floor transmit tensile forces between the ends of the concrete floor in the first intersecting direction and between the ends in the second intersecting direction, respectively. During a fire, the rigidity and strength of the multiple fire-resistant beams decrease, causing the floor to deflect due to gravity and other factors acting on it, resulting in the central part of the floor becoming convex downwards in a plan view. However, due to the membrane effect, the perimeter of the floor is supported by the fire-resistant annular body. As the floor deflects, the stretched tensile force transmission members transmit tensile forces in the first and second intersecting directions, respectively, thereby supporting the central part of the floor. Therefore, deflection of the floor during a fire can be suppressed.

[0008] (2) Embodiment 2 of the present invention may be the fire-resistant structure described in (1), wherein the material axis direction of the first fire-reducing beam and the material axis direction of the second fire-reducing beam are perpendicular to each other. In this invention, the space formed between the first fire-reducing beam and the second fire-reducing beam within the fire-resistant annular structure can be made wider in each case compared to the case where the axial directions of both members do not intersect but are not perpendicular to each other.

[0009] (3) Embodiment 3 of the present invention may be a fire-resistant structure as described in (1) or (2), wherein the end of each of the target fire-reducing beams is joined to the plurality of fire-reducing beams via or directly to the plurality of fire-reducing beams other than the target fire-reducing beam. In this invention, under normal circumstances, the end of the target fire-reducing beam can be supported by joining it to multiple fire-resistant beams, either via other fire-reducing beams among the multiple fire-reducing beams, or directly to multiple fire-resistant beams. [Effects of the Invention]

[0010] The fire-resistant structure of the present invention allows for greater flexibility in the arrangement of fire-reducing covering beams and suppresses deflection of the floor section at high temperatures. [Brief explanation of the drawing]

[0011] [Figure 1] It is a perspective view schematically showing a fire-resistant structure according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view taken along cutting line A1-A1 in FIG. 1. [Figure 3] It is a perspective view of a reinforcing bar in the fire-resistant structure. [Figure 4] It is a perspective view modeling an example of a conventional fire-resistant structure. [Figure 5] It is a perspective view modeling another example of a conventional fire-resistant structure. [Figure 6] It is a perspective view modeling a fire-resistant structure according to an embodiment of the present invention. [Figure 7] It is a diagram showing a change in deflection at the center of a floor portion with respect to time. [Figure 8] It is a diagram showing a change in compressive force in a first intersecting direction of a floor portion with respect to time. [Figure 9] It is a perspective view modeling a fire-resistant structure according to a first modification of an embodiment of the present invention. [Figure 10] It is a perspective view modeling a fire-resistant structure according to a second modification of an embodiment of the present invention.

Mode for Carrying Out the Invention

[0012] Hereinafter, an embodiment of a fire-resistant structure according to the present invention will be described with reference to FIG. 1 to FIG. 10. As shown in FIG. 1, the fire-resistant structure 1 of the present embodiment includes a floor portion 10, a plurality of fire-resistant performance beams 25, a plurality of fire-resistant performance columns 40, and a plurality of reduced fire-resistant performance beams 45. In FIG. 1, the floor portion 10 is shown in a see-through manner. In FIG. 1, columns and beams having predetermined fire resistance performance to be described later are shown with hatching.

[0013] In the present embodiment, the floor portion 10 is in a flat plate shape having a rectangular shape when viewed in the thickness direction of the floor portion 10. The floor portion 10 is arranged such that the thickness direction of the floor portion 10 is along the vertical direction Z. Note that the floor portion 10 may be arranged such that the thickness direction intersects the vertical direction Z. Here, the directions that intersect each other orthogonally within the upper surface (plane) of the floor portion 10 are defined as the first intersecting direction X and the second intersecting direction Y. The first intersecting direction X is the longitudinal direction of the floor portion 10 when viewed in the vertical direction Z. The second intersecting direction Y is the short direction of the floor portion 10 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 intersect each other within the upper surface of the floor portion 10.

[0014] In this embodiment, the floor section 10 is divided into multiple (three in this embodiment) regions in the first intersecting direction X by the first fire-resistant beams 46A and 46C, which will be described later. These multiple regions are referred to as the first floor section 10A, the second floor section 10B, and the third floor section 10C. The first floor section 10A, the second floor section 10B, and the third floor section 10C are arranged in this order from the first side X1 in the first intersecting direction X toward the second side X2, which is opposite to the first side X1 in the first intersecting direction X. The first floor section 10A, the second floor section 10B, and the third floor section 10C differ from each other only in the main reinforcement directions WA, WC and WB, which will be described later.

[0015] As shown in Figure 2, the floor section 10 is a so-called reinforced concrete truss deck slab. The floor section 10 comprises 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, although this is not shown in detail. However, in this example, the deck plate 11 is treated as a sacrificial formwork for the concrete 12 and is designed not to exhibit any composite effect with the concrete 12. The concrete 12 has the same shape as the floor 10 when viewed in the vertical direction Z. The concrete 12 is placed on the deck plate 11. The reinforcing bars 13 are provided in the concrete 12.

[0016] The configuration of the reinforcing bars 13 in the second floor section 10B is not particularly limited, as long as it has first reinforcing bars extending along the first intersecting direction X and second reinforcing bars extending along the second intersecting direction Y. As shown in Figures 2 and 3, in this embodiment, the reinforcing bars 13 have a plurality of first reinforcing bars 15, 16 and a plurality of second reinforcing bars 17.

[0017] Each of the first reinforcing bars 15 and 16 extends along the first intersecting direction X. The first reinforcing bar 15 is positioned above the first reinforcing bar 16. The first reinforcing bars 15 and 16 are arranged side by side with spacing between them in the vertical direction Z. Multiple first reinforcing bars 15 are arranged with spacing between them in the second intersecting direction Y. The same applies to multiple first reinforcing bars 16 as to multiple first reinforcing bars 15. The first reinforcing bars 15 and 16 each extend to the respective ends of the concrete 12 of the second floor section 10B in the first intersecting direction X. The first reinforcing bars 15 and 16 each transmit the tensile force between the ends of the concrete 12 (floor section 10) of the second floor section 10B in the first intersecting direction X.

[0018] As shown in Figure 3, the first reinforcing bars 15 and 16 are joined to each other by a first connecting member 19. The first connecting member 19 extends along the first intersecting direction X and is zigzag in shape, alternately bending in the vertical direction Z. Multiple first reinforcing bars 15 are joined to each other by multiple second connecting members 20. Each second connecting member 20 extends along the second intersecting direction Y and is zigzag in shape, alternately bending in the vertical direction Z. In each second connecting member 20, peaks and valleys are arranged alternately in the second intersecting direction Y. The first reinforcing bar 15 is joined to the upper end of the ridge portion of the second connecting member 20.

[0019] Each second reinforcing bar 17 extends along the second intersecting direction Y. Multiple second reinforcing bars 17 are spaced apart from each other in the first intersecting direction X. The second reinforcing bars 17 extend to each end of the concrete 12 of the second floor section 10B in the second intersecting direction Y. The second reinforcing bars 17 transmit tensile forces between the ends of the concrete 12 of the second floor section 10B in the second intersecting direction Y. The multiple second reinforcing bars 17 are joined to the multiple first reinforcing bars 15 by welding, binding wire, or the like.

[0020] As described above, the reinforcing bars 13 are integrated into a block-like structure as a whole. In the second floor section 10B, the main reinforcement direction WB in which the first reinforcing bars 15 and 16 extend is the first intersecting direction X (see Figure 1). Similarly, the main reinforcement direction WA in which the first reinforcing bars 15 and 16 extend in the first floor section 10A, and the main reinforcement direction WC in which the first reinforcing bars 15 and 16 extend in the third floor section 10C, are the second intersecting direction Y, respectively. For example, the reinforcing bars 13 of the first floor section 10A and the reinforcing bars 13 of the second floor section 10B are connected to each other by a joint (mechanical joint), etc. The same applies to the second floor section 10B and the third floor section 10C. Specifically, multiple second reinforcing bars 17 of the reinforcing bar 13 in the first floor section 10A and multiple first reinforcing bars 15 of the reinforcing bar 13 in the second floor section 10B are connected to each other by joints, etc. Multiple first reinforcing bars 15 of the reinforcing bar 13 in the second floor section 10B and multiple second reinforcing bars 17 of the reinforcing bar 13 in the third floor section 10C are connected to each other by joints, etc.

[0021] As configured as described above, the reinforcing bars 13 of each floor piece 10A, 10B, and 10C as a whole transmit tensile forces between the ends of the concrete 12 (floor section 10) in the first intersecting direction X, as well as tensile forces between the ends of the concrete 12 in the second intersecting direction Y, to the entire concrete 12 of the floor section 10. The floor section 10 may not be divided into multiple areas, but may be integrated into a single unit. In this case, the entire floor section 10 will have a single main reinforcement direction. The floor section 10 may be a so-called composite slab or a so-called reinforced concrete slab that does not have a deck plate 11.

[0022] As shown in Figure 1, the multiple fire-resistant beams 25 include a pair of first fire-resistant beams 26 and a pair of second fire-resistant beams 27. As shown in Figure 2, for example, the first fire-resistant beam 26 is an H-shaped steel beam 31 with a fire-resistant coating 30. In other words, the first fire-resistant beam 26 is coated with a fire-resistant coating 30. The fire-resistant coating 30 uses insulating materials such as rock wool or glass wool. In this case, the fire-resistant coating 30 is applied to the H-shaped steel 31 by a spraying method.

[0023] For example, the thickness of the fire-resistant coating 30, such as rock wool, on the first fire-resistant beam 26 is set in accordance with the "Guidelines for Construction Quality Management of Sprayed Rock Wool Coated Fire-Resistant Structures (Rock Wool Industry Association, Spraying Division)". If the first fire-resistant beam 26 is required to have 1 hour fire resistance, the thickness of the fire-resistant coating 30 is set to 25 mm. Similarly, if the first fire-resistant beam 26 is required to have 2 hours fire resistance, the thickness of the fire-resistant coating 30 is set to 45 mm. If the first fire-resistant beam 26 is required to have 3 hours fire resistance, the thickness of the fire-resistant coating 30 is set to 60 mm. Hereafter, the fire resistance performance based on these Guidelines for Construction Quality Management of Sprayed Rock Wool Coated Fire-Resistant Structures will be referred to as the coating fire resistance performance (specified fire resistance performance). Furthermore, the specified fire resistance performance is not limited to the fire resistance performance of the coating. The fire-resistant coating of the second fire-resistant beam 27 is the same as that of the first fire-resistant beam 26. Multiple fire-resistant beams 25 have fire-resistant coatings.

[0024] Fire-resistant beams may be made of reinforced concrete or steel-reinforced concrete and may not have fire-resistant coatings. Because concrete itself has fire-resistant properties, there is no need to apply fire-resistant coatings to fire-resistant beams made of reinforced concrete or steel-reinforced concrete. Fire-resistant coating may be applied to the fire-resistant beams 26 and 27 by a molded plate method or a wrapping method.

[0025] The H-shaped steel beam 31 has a web 31a and an upper flange 31b and a lower flange 31c positioned on either side of the web 31a. The upper flange 31b is positioned above the lower flange 31c. As shown in Figure 1, the second fire-resistant beam 27 is an H-shaped steel (not shown) with a fire-resistant coating 34, similar to the first fire-resistant beam 26. A pair of first fire-resistant beams 26 extend along the first intersecting direction X. The pair of first fire-resistant beams 26 are spaced apart from each other in the second intersecting direction Y. A pair of second fire-resistant beams 27 extend along the second intersecting direction Y. The pair of second fire-resistant beams 27 are spaced apart from each other in the first intersecting direction X. A gap is formed between the first fire-resistant beam 26 and the second fire-resistant beam 27, in which a fire-resistant column 40 is positioned.

[0026] As shown in Figure 2, a headed stud 38 and a gusset plate 39 are fixed to the first fire-resistant beam 26. The headed studs 38 are fixed to the upper surface of the upper flange 31b of the H-shaped steel beam 31 by welding or the like. The headed studs 38 penetrate the deck plate 11 of the floor section 10 and are embedded in the concrete 12. The gusset plate 39 is fixed to the web 31a and flanges 31b and 31c of the H-shaped steel beam 31. The gusset plate 39 protrudes from the H-shaped steel beam 31 in the width direction (second intersecting direction Y) of the H-shaped steel beam 31. Similar to the first fire-resistant beam 26, the second fire-resistant beam 27 is fitted with headed studs and gusset plates (not shown).

[0027] As shown in Figure 1, for example, the fire-resistant column 40 is a square steel pipe (not shown) with a fire-resistant coating 41. In other words, the fire-resistant column 40 is coated with a fire-resistant coating 41. Multiple fire-resistant columns 40 extend along the vertical direction Z. In this embodiment, multiple fire-resistant columns 40 are positioned below multiple corners of the floor section 10. The ends of multiple fire-resistant beams 25 are rigidly joined to the upper ends (partially) of the multiple fire-resistant columns 40. In other words, the upper end of each fire-resistant column 40 is joined to the first fire-resistant beam 26 and the second fire-resistant beam 27, respectively. Multiple fire-resistant columns 40 support multiple fire-resistant beams 25. In this embodiment, multiple fire-resistant columns 40 are joined to all of the multiple fire-resistant beams 25.

[0028] The fire-resistant coating 41 of the fire-resistant column 40 is constructed in the same manner as the fire-resistant coatings 30 and 34 of the fire-resistant beam 25. In other words, multiple fire-resistant columns 40 have fire-resistant coatings. The upper ends of multiple fire-resistant columns 40 and the entirety of multiple fire-resistant beams 25 form an annular fire-resistant annular body 43.

[0029] The fire-resistant ring-shaped body 43 supports the floor section 10 from below, around its entire circumference. Furthermore, the fire-resistant columns may be H-shaped steel beams with fire-resistant coatings or circular steel pipes with fire-resistant coatings. Fire-resistant columns may be made of concrete-filled steel pipes, reinforced concrete, or steel-reinforced concrete, without fire-resistant coating.

[0030] Multiple fire-resistant beams 45 do not have fire-resistant coatings. For example, multiple fire-resistant beams 45 are not coated with fire-resistant coatings. Furthermore, multiple fire-resistant beams 45 may be coated with fire-resistant coatings. In this case, for example, the thickness of the fire-resistant coating on each fire-resistant beam 45 should be about 1 / 10 to 1 / 2 of the thickness of the fire-resistant coating based on the respective coating's fire-resistant performance. Multiple fire-resistant beams 45 are arranged within the fire-resistant ring-shaped body 43 and support the floor section 10 from below. The multiple fire-resistant beams 45 include first fire-resistant beams 46A, 46B, and 46C, and second fire-resistant beams 47A, 47B, 47C, and 47D.

[0031] The first fire-reducing beams 46A to 46C each extend along the second intersecting direction Y and are arranged at intervals from each other in the first intersecting direction X. The first fire-reducing beams 46A to 46C are arranged in the middle of the pair of first fire-resistant beams 26 in the first intersecting direction X, in this order from the first side X1 to the second side X2 in the first intersecting direction X. The first fire-reducing beams 46A to 46C may also extend to intersect the second intersecting direction Y, and they do not have to be parallel to each other. The second fire-resistant beams 47A to 47D each extend along the first intersecting direction X. The second fire-resistant beams 47A and 47B are spaced apart from each other between the second fire-resistant beam 27 and the first fire-resistant beam 46A on the first side X1, in the order from the first side Y1 to the second side Y2 in the second intersecting direction Y. The second fire-resistant beams 47C and 47D are spaced apart from each other between the second fire-resistant beam 27 and the first fire-resistant beam 46C on the second side X2, in the order from the first side Y1 to the second side Y2 in the second intersecting direction Y. Note that the second fire-resistant beams 47A to 47D may extend intersecting the first intersecting direction X, and they do not have to be parallel to each other.

[0032] Next, regarding the connection structure between the fire-resistant beam 25 and the fire-reducing beam 45, we will explain using the connection structure between the first fire-resistant beam 26 and the first fire-reducing beam 46B as an example. As shown in Figure 2, the first fire-resistant beam 46B is made of H-shaped steel without fire-resistant coating. The first fire-resistant beam 46B has a web 46aB and an upper flange 46bB and a lower flange 46cB positioned on either side of the web 46aB. The upper flange 46bB is positioned above the lower flange 46cB. The gusset plate 39 of the first fire-resistant beam 26 and the web 46aB of the first fire-reducing beam 46B are joined by high-strength bolts 50, etc. In this way, the ends of the first fire-resistant beam 26 and the first fire-reducing beam 46B are joined by a so-called pin joint. A headed stud 51 is fixed to the upper flange 46bB of the first fire-resistant beam 46B. The headed stud 51 penetrates the deck plate 11 and is embedded in the concrete 12.

[0033] In this embodiment, each end of the first fire-resistant beams 46A to 46C is connected to the first fire-resistant beam 26 by pin connections. Each end of the second fire-resistant beams 47A and 47B is connected to the second fire-resistant beam 27 and the first fire-resistant beam 46A on the first side X1 by pin connections. Each end of the second fire-resistant beams 47C and 47D is connected to the second fire-resistant beam 27 and the first fire-resistant beam 46C on the second side X2 by pin connections.

[0034] Here, as shown in Figure 1, for example, the first fire-resistant beam 46A will be used as the target fire-resistant beam 45A for which the connection will be explained. Both ends of the target fire-resistant beam 45A are directly connected to a pair of first fire-resistant beams 26 (multiple fire-resistant beams 25). Furthermore, for example, the second fire-resistant beam 47A will be explained using the target fire-resistant beam 45B as an example. The first end of the target fire-resistant beam 45B is joined to the second fire-resistant beam 27 on the first side X1. The second end of the target fire-resistant beam 45B, opposite to the first end, is joined to a pair of first fire-resistant beams 26 (multiple fire-resistant beams 25) via the first fire-resistant beam 46A, which is a fire-resistant beam 45 other than the target fire-resistant beam 45B among the multiple fire-resistant beams 45.

[0035] The second intersecting direction Y, which is the material axis direction (longitudinal direction) of the first fire-resistant beam 46A (one of the multiple fire-resistant beams 45), and the first intersecting direction X, which is the material axis direction of the second fire-resistant beam 47A (another of the multiple fire-resistant beams 45), are perpendicular to each other. The same applies to the first fire-resistant beam 46A and the second fire-resistant beam 47B, and to the first fire-resistant beam 46C and the second fire-resistant beams 47C and 47D. Furthermore, the first fire-reducing beams 46A and 46C may be configured such that their material axis directions intersect with those of the second fire-reducing beams 47A, 47B, 47C, and 47D, even if they are not perpendicular to each other.

[0036] The fire-resistant structure 1, configured as described above, can be used, for example, by placing equipment such as desks and filing cabinets on the floor portion 10.

[0037] (Simulation results) As conventional (comparative) fire-resistant structures, fire-resistant structures 1A and 1B shown in Figures 4 and 5 were modeled. The fire-resistant structure 1A shown in Figure 4 has multiple (seven in this example) first fire-reducing beams 46A to 46G instead of the fire-reducing beams 46A to 46C and 47A to 47D of the fire-resistant structure 1 in this embodiment. In Figures 4 to 6, the fire-resistant beams are indicated by dotted lines. Note that Figures 4 to 6 do not show the floor section 10. In Figure 4, the cross-sectional dimensions of the H-shaped steel for fire-resistant beams 26 and 27 were set to H-1000 × 400 × 19 × 28. The length (L) of the first fire-resistant beam 26 was set to 19,200 mm. The length (l) of the second fire-resistant beam 27 was set to 7,200 mm. The cross-sectional dimensions of the H-shaped steel for the first fire-reducing beams 46A to 46G were set to H-500 × 200 × 10 × 16. No fire-resistant coating was applied to the first fire-reducing beams 46A to 46G.

[0038] Furthermore, it was assumed that the rigidity of the fire-resistant beam 45 would decrease during a fire, based on Reference 1. Specifically, the rigidity of the fire-resistant beam 45 is equal to its rigidity at room temperature below 100°C. Above 100°C, the rigidity of the fire-resistant beam 45 decreases, and at 1200°C, the rigidity of the fire-resistant beam 45 is lost. Document 1: "Eurocode 3: Design of steel structures - Part 1-2: General rules - Structural fire design" en. 1993-1-2, 2005

[0039] As shown in Figure 4, the fire-resistant beams 26 and 27 can rotate around the first intersecting direction X, the second intersecting direction Y, and the vertical direction Z relative to the upper end of each fire-resistant column 40. For fire-resistant column 40A, which is one of several fire-resistant columns 40, the fire-resistant beams 26 and 27 are fixed in the first intersecting direction X, the second intersecting direction Y, and the vertical direction Z, respectively. For fire-resistant column 40B, which is one of the several fire-resistant columns 40 other than fire-resistant column 40A, the fire-resistant beams 26 and 27 are movable in the first intersecting direction X and the second intersecting direction Y, respectively. For fire-resistant column 40B, the fire-resistant beams 26 and 27 are fixed in the vertical direction Z, respectively.

[0040] The floor section 10 used in the fire-resistant structure 1A is integrated into a single unit without being divided into multiple floor pieces. Figure 4 shows the main reinforcement direction W1 of reinforcing bar 13.

[0041] In the fire-resistant structure 1B shown in Figure 5, the first fire-reducing performance beams 46A and 46C of the fire-resistant structure 1 of this embodiment are replaced with second fire-resistant performance beams 27A and 27B. The specifications of the second fire-resistant performance beams 27A and 27B are the same as those of the first fire-resistant performance beam 26. In the fire-resistant structure 1B, the fire-resistant annular body 43 contains other second fire-resistant performance beams 27A and 27B that are not used in the fire-resistant annular body 43. The floor section 10 has floor pieces 10A, 10B, and 10C, and Figure 5 shows the main reinforcement directions WA, WB, and WC for floor pieces 10A, 10B, and 10C. In fire-resistant structure 1B, the structure in which the second fire-resistant beams 27A and 27B are not covered with fire-resistant coating and the first fire-reducing beams 46A and 46C are used is fire-resistant structure 1 shown in Figure 6.

[0042] The following specifications were adopted for fire-resistant structures 1A, 1B, and 1. The thickness of the floor section 10 was set to 140 mm. The first reinforcement bars 15 and 16 were D13@200. The second reinforcement bar 17 was D10@150. The overall vertical Z length (thickness) of reinforcement bar 13 was set to 100 mm. The fire-resistant coating of the fire-resistant beams 26 and 27 was to be applied using a spray method with a thickness of 45 mm semi-dry rock wool (RW). Floor section 10, 10kN / m 2 A vertical load was applied. The fire-resistant structures 1A, 1B, and 1 were assumed to be heated for 120 minutes (2 hours) based on the standard heating curve specified in ISO 834-11:2014. The simulation results are shown in Figures 7 and 8.

[0043] Figure 7 shows the change in deflection at the center of the floor section 10 over time. The center of the floor section 10 is the center of the floor section 10 when viewed in the vertical direction Z. In Figure 7, the horizontal axis represents time (minutes), and the vertical axis represents the deflection at the center of the floor section 10 (mm). In Figure 7, the line L0 shows the deflection limit value obtained as (L+l) / 30 based on the following literature. Literature: Olivier Vassart, Bin Zhao “MEMBRANE ACTION OF COMPOSITE STRUCTURES IN CASE OF FIRE”, 2013 No.132, ECCS, Technical Committee 3 Fire Safety. The simulation results for fire-resistant structures 1A, 1B, and 1 are shown along line L. 1A1 ,L 1B1 ,L 11 These are shown below.

[0044] The deflection at the center of the floor section 10 at a predetermined time (time) increases in the order of fire-resistant structure 1B, 1A, and 1. However, even with fire-resistant structure 1, it was found that the deflection at the center of the floor section 10 after 120 minutes of heating was below the deflection limit and was within an acceptable range.

[0045] Figure 8 shows the change in compressive force of the floor section 10 in the first intersecting direction X over time in the fire-resistant structure 1B,1. The compressive force in the fire-resistant structure 1B,1 is within the range R shown in Figures 5 and 6. 1B R1 represents the compressive force in the first intersecting direction X. In Figure 8, the horizontal axis represents time (minutes), and the vertical axis represents the compressive force (kN / m) in the first intersecting direction X of the floor section 10. The simulation results for fire-resistant structure 1B,1 are shown along line L 1B2 ,L 12 These are shown below. The compressive force of fire-resistant structure 1 is equivalent to that of fire-resistant structure 1B for approximately 15 minutes from the start of heating. However, after 15 minutes from the start of heating, the compressive force of fire-resistant structure 1 decreases compared to that of fire-resistant structure 1B. This is thought to be because, in fire-resistant structure 1B, the second fire-resistant beam 27A restrains the thermal expansion occurring in the plane of the first floor piece 10A, whereas in fire-resistant structure 1, the first fire-reducing beam 46A does not restrain it. In the fire-resistant structure 1 of this embodiment, since the first fire-reducing beams 46A and 46C are not covered with fire-resistant coating, it was found that the compressive force is lower compared to the fire-resistant structure 1B.

[0046] Furthermore, the fire-resistant structure 1 of this embodiment can be modified in various ways, as described below. As shown in Figure 9, the first modified example of a fire-resistant structure 1C may be configured to include a plurality of fire-reducing beams 45, namely first fire-reducing beams 46A to 46F and second fire-reducing beams 47A and 47B. The ends of the second fire-reducing beams 47A and 47B are joined to multiple fire-resistant beams 25 via the first fire-reducing beams 46C and 46D.

[0047] As shown in Figure 10, the fire-resistant structure 1D of the second modified example may be configured to have multiple fire-reducing beams 45, namely first fire-reducing beams 46A to 46E and second fire-reducing beams 47A to 47D. The ends of the second fire-reducing beams 47A and 47B are joined to multiple fire-resistant beams 25 via the first fire-reducing beams 46B and 46C. The ends of the second fire-reducing beams 47C and 47D are joined to multiple fire-resistant beams 25 via the first fire-reducing beams 46C and 46D.

[0048] As described above, in the fire-resistant structure 1 of this embodiment, under normal conditions (at room temperature), the second intersecting direction Y, which is the material axis direction of the first fire-reducing beam 46A, and the first intersecting direction X, which is the material axis direction of the second fire-reducing beam 47A, intersect. This allows for greater freedom in the arrangement of the fire-reducing beams 45 compared to the case where multiple fire-reducing beams are parallel to each other. On the other hand, the floor section 10 is supported from below around its entire perimeter by the fire-resistant annular body 43, which maintains a certain rigidity and strength even during a fire. The reinforcing bars 13 provided in the floor section 10 transmit the tensile force between the ends in the first intersecting direction X and the tensile force between the ends in the second intersecting direction Y of the concrete 12 of the floor section 10, respectively. During a fire, the rigidity and strength of the multiple fire-reducing beams 45 decrease, causing the floor section 10 to sag due to gravity acting on it, resulting in the central part of the floor section 10 becoming convex downwards in a plan view. However, due to the membrane effect, the perimeter of the floor section 10 is supported by the fire-resistant annular body 43. As the floor section 10 sags, the reinforcing bars 13 stretch and transmit tensile forces in the first intersecting direction X and the second intersecting direction Y, respectively, thereby supporting the central part of the floor section 10. Therefore, the deflection of the floor section 10 during a fire can be suppressed. Since no fire-resistant beams 25 are placed within the fire-resistant ring-shaped body 43, the compressive force acting on the floor 10 can be reduced, allowing the floor 10 to be used for a longer period of time.

[0049] The second intersecting direction Y, which is the material axis direction of the first fire-reducing beam 46A, and the first intersecting direction X, which is the material axis direction of the second fire-reducing beam 47A, are perpendicular to each other. Therefore, within the fire-resistant annular body 43, the space formed between the first fire-reducing beam 46A and the second fire-reducing beam 47A can be made wider in each case compared to the case where the material axes of both beams do not intersect perpendicularly to each other. The ends of the target fire-reducing beams 45A and 45B are joined to multiple fire-resistant beams 25 either via the first fire-reducing beam 46A or directly. Therefore, under normal circumstances, the ends of the target fire-reducing beams 45A and 45B can be supported by joining them to multiple fire-resistant beams 25 either via the first fire-reducing beam 46A other than the target fire-reducing beams 45A and 45B, or directly.

[0050] The floor section 10 may be a composite slab. In this case, since composite slabs are widely used as floor sections, the floor section 10 can be constructed at a low cost. Each of the multiple fire-resistant beams 25 is an H-shaped steel beam with a fire-resistant coating. Since H-shaped steel beams are widely used as beams, the fire-resistant beams 25 can be constructed inexpensively.

[0051] Each of the multiple fire-resistant columns 40 is an H-shaped steel beam coated with a fire-resistant coating 41. Since H-shaped steel beams are widely used as columns, the fire-resistant columns 40 can be constructed inexpensively. In the first fire-resistant beam 26, the fire-resistant coating 30 is applied by spraying. Since the spraying method is widely used to apply fire-resistant coatings to H-shaped steel and the like, the fire-resistant coating 30 can be applied inexpensively.

[0052] 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 modifications, combinations, deletions, etc., of the configuration are also included without departing from the spirit of the present invention. For example, in the above embodiment, the first fire-resistant beam 26 and the second fire-resistant beam 27 may be directly joined without the fire-resistant column 40. In this case, the annular fire-resistant annular body is composed of a plurality of fire-resistant beams 25. If the deck plate 11 is sufficiently thick, the tensile force transmission member may be the deck plate 11. [Explanation of Symbols]

[0053] 1 Fireproof structures 10 Floor 12 Concrete 13. Reinforcing bars (tensile force transmission members) 25 Fire resistance beam 30,34 Fire-resistant coating 40 Fire resistance performance pillar 43 Fire-resistant ring body 45 Reduced fire resistance beam 45A, 45B Target fire-resistant beams 46A, 46B, 46C, 46D, 46E, 46F 1st reduced fire resistance performance beam 47A, 47B, 47C, 47D 2nd reduced fire resistance beam X 1st cross direction Y Second Intersection Direction

Claims

1. A floor section in which a tensile force transmission member is provided in concrete, Multiple fire-resistant beams having a predetermined fire resistance performance, Multiple fire-resistant columns having the predetermined fire-resistant performance, joined to the multiple fire-resistant beams, and an annular fire-resistant annular body formed by a part of itself and the entirety of the multiple fire-resistant beams, supporting the floor from below around its entire circumference; A plurality of fire-resistant beams, which are arranged within the fire-resistant annular body and support the floor from below, without possessing the predetermined fire-resistant performance, Equipped with, When the directions that intersect each other within the plane of the floor are defined as the first intersecting direction and the second intersecting direction, The tensile force transmission member transmits the tensile force between the ends of the floor portion in the first intersecting direction and the tensile force between the ends of the floor portion in the second intersecting direction, respectively. A fire-resistant structure in which the material axis direction of one of the multiple fire-reducing beams, namely the first fire-reducing beam, intersects with the material axis direction of another of the fire-reducing beams, namely the second fire-reducing beam.

2. The fire-resistant structure according to claim 1, wherein the material axis direction of the first fire-reducing beam and the material axis direction of the second fire-reducing beam are perpendicular to each other.

3. The fire-resistant structure according to claim 1 or 2, wherein the end of each of the target fire-reducing beams is joined to the plurality of fire-reducing beams via or directly to the plurality of fire-reducing beams other than the target fire-reducing beam.

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