JP2023002223A - Refractory structure design method, refractory structure construction method, and refractory structure - Google Patents

Abstract

To provide a refractory structure design method which improves refractory performance.SOLUTION: A refractory structure design method S10 includes structure setting step S11 for setting the arrangement of a floor section, a plurality of beams supporting the floor section from underneath, and a plurality of columns joined to the plurality of beams by performing structural calculation, first refractory specification setting step S13 for setting such that the surroundings of the floor section are supported from underneath by a plurality of refractory coating beams in which refractory coating is applied to a part of the plurality of beams, second refractory specification setting step S15 for setting such that refractory coating is applied to the plurality of columns to make a plurality of refractory coating columns, and third refractory specification setting step S17 for setting such that a reduced refractory coating beam which is a remaining part of the plurality of beams or a reduced refractory coating beam in which refractory coating is applied to the remaining part of the plurality of beams is disposed in an area and an end of the reduced refractory coating beam is joined to the refractory coating beam to support the floor section from underneath.SELECTED DRAWING: Figure 5

Description

The present invention relates to a fire-resistant structure design method, a fire-resistant structure construction method, and a fire-resistant structure.

Conventionally, in fire-resistant structures, slabs (floors) are supported by large girders and small steel beams (reduced fire-resistant covered beams) (see, for example, Patent Document 1). The girders are made of reinforced concrete and spanned between pillars. The steel beams consist entirely of H-beams without fireproof coating. The steel girders are joined to the slab by studs welded to the upper flanges.

In the event of a fire, the heat may reduce the load bearing capacity of the steel beams or cause the steel beams to melt. However, slabs are designed to be thick enough to withstand long-term loads without steel beams. Therefore, the slab is prevented from coming off due to the strength of the slab itself.

JP 2017-190586 A

However, the conventional fire-resistant structure design method leaves room for improvement in fire-resistant performance.

The present invention has been made in view of such problems, and an object of the present invention is to provide a method for designing a fire-resistant structure with improved fire-resistant performance, a method for constructing a fire-resistant structure, and a fire-resistant structure. .

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 portion provided with a tensile force transmission member in concrete, a plurality of fireproof coated beams that are coated with fireproof coating and support the periphery of the floor portion from below, a plurality of fire-resistant coated columns that are coated with a fire-resistant coating and joined to the ends of the plurality of fire-resistant coated beams so that a part of the columns themselves and the plurality of fire-resistant coated beams are formed in an annular shape as a whole; a steel, having less of the refractory cladding than the refractory cladding beams, disposed within an area surrounded by the plurality of refractory cladding beams and the plurality of refractory cladding columns, and ending with the plurality of refractory cladding beams; and a beam covered with reduced fire resistance that supports the floor from below, and when the directions that intersect each other in the plane of the floor are defined as a first intersecting direction and a second intersecting direction, the tension A force transmission member designs a refractory structure that transmits a tensile force between said first transverse ends of said floor and a tensile force between said second transverse ends of said floor respectively. A method for designing a fire-resistant structure, wherein 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 is set by performing structural calculations. a structure setting step, a first fireproof specification setting step of setting the periphery of the floor so as to be supported from below by the plurality of fireproof coated beams in which a part of the plurality of beams is fireproof coated; A second fire-resistant specification setting step of applying fire-resistant coating to the columns and setting them to the plurality of fire-resistant coated columns; The third fire-resistant specification is set so that the reduced fire-resistant coated beams are placed in the area, and the ends of the reduced fire-resistant coated beams are joined to the fire-resistant coated beams to support the floor from below. a setting step;

The provision of the tensile force transmission member in the concrete as used herein includes the state in which a part of the tensile force transmission member is exposed from the concrete.

(2) In the method for designing a fire-resistant structure described in (1) above, the welded assembled H-section steel of the reduced fire-resistant coated beam has a yield strength at room temperature of 235 (N/mm ² ) or more, good too.
The normal temperature referred to here means 5° C. or more and 35° C. or less.
(3) In the method for designing a refractory structure according to (1) or (2) above, the cross-sectional area (mm ² ) perpendicular to the longitudinal direction of the welded assembled H-section steel and the room temperature of the welded assembled H-section steel The product with the yield strength (N/mm ² ) in 1000 kN or more and 6000 kN or less may be sufficient.

(4) In the method for designing a fire-resistant structure according to any one of (1) to (3) above, the floor may be a synthetic slab or a reinforced concrete slab.
(5) In the method for designing a fire-resistant structure according to any one of (1) to (4), the tensile force transmission member extends along the first intersecting direction and extends along the first cross direction of the floor. A first reinforcing bar that transmits tensile force between ends in one crossing direction, and a second reinforcing bar that extends along the second crossing direction and transmits tensile force between ends of the floor in the second crossing direction. and may have

(6) In the method for designing a fire-resistant structure according to any one of (1) to (5) above, the fire-resistant coated beam is made of H-shaped steel, reinforced concrete, or steel-reinforced concrete with the fire-resistant coating. may be made.
(7) In the method for designing a fire-resistant structure according to any one of (1) to (6) above, the fire-resistant coated columns are H-section steel coated with the fire-resistant coating, square steel pipes, circular steel pipes with the fireproof coating, concrete-filled steel pipes, reinforced concrete, or steel-reinforced concrete.

(8) In the method for designing a fire-resistant structure according to any one of (1) to (7) above, the fire-resistant coating may be applied by a spraying method, a molded plate method, or a winding method. .

(9) A second aspect of the present invention includes a floor section provided with a tensile force transmission member in concrete, a plurality of fireproof coated beams that are coated with a fireproof coating and support the periphery of the floor section from below, a plurality of fire-resistant coated columns that are coated with a fire-resistant coating and joined to the ends of the plurality of fire-resistant coated beams so that a part of the columns themselves and the plurality of fire-resistant coated beams are formed in an annular shape as a whole; a steel, having less of the refractory cladding than the refractory cladding beams, disposed within an area surrounded by the plurality of refractory cladding beams and the plurality of refractory cladding columns, and ending with the plurality of refractory cladding beams; and a beam covered with reduced fire resistance that supports the floor from below, and when the directions that intersect each other in the plane of the floor are defined as a first intersecting direction and a second intersecting direction, the tension The force transmission member constructs a refractory structure that transmits a tensile force between the ends of the floor in the first cross direction and a tensile force between the ends of the floor in the second cross direction, respectively. A construction method for a refractory structure, comprising: a column-beam construction step of constructing the floor, a plurality of beams supporting the floor from below, and a plurality of columns joined to the plurality of beams; A first coating step of supporting the periphery of the above from below by the plurality of fireproof coated beams in which a part of the plurality of beams is fireproof coated, and applying a fireproof coating to the plurality of columns to form the plurality of fireproof coated columns and the reduced fire resistant coated beams that are the remainder of the plurality of beams, or the reduced fire resistant coated beams that are the remainder of the plurality of beams with fire resistant coating, are arranged in the region, and a third covering step of joining the ends of the reduced fire resistant coated beams to the fire resistant coated beams to support the floor from below.

(10) A third aspect of the present invention includes a floor portion provided with a tensile force transmission member in concrete, a plurality of fireproof coated beams that are coated with fireproof coating and support the periphery of the floor portion from below, a plurality of fire-resistant coated columns that are coated with a fire-resistant coating and joined to the ends of the plurality of fire-resistant coated beams so that a part of the columns themselves and the plurality of fire-resistant coated beams are formed in an annular shape as a whole; a steel, having less of the refractory cladding than the refractory cladding beams, disposed within an area surrounded by the plurality of refractory cladding beams and the plurality of refractory cladding columns, and ending with the plurality of refractory cladding beams; and a beam covered with reduced fire resistance that supports the floor from below, and when the directions that intersect each other in the plane of the floor are defined as a first intersecting direction and a second intersecting direction, the tension The force transmission member is a refractory structure that transmits a tensile force between the ends of the floor in the first cross direction and a tensile force between the ends of the floor in the second cross direction. .

The method for designing a fire-resistant structure, the method for constructing a fire-resistant structure, and the fire-resistant structure of the present invention can improve fire resistance performance.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows typically the fireproof structure of one Embodiment of this invention. 2 is a cross-sectional view taken along a cutting line A1-A1 in FIG. 1; FIG. It is a perspective view of the reinforcing bar in the same fire-resistant structure. It is a figure which shows an example of the change of the yield strength with respect to temperature in steel materials. It is a flow chart which shows a design method of a fire-resistant structure in one embodiment of the present invention. It is a perspective view of the foundation structure in the design method of the same fire-resistant structure. It is a flow chart which shows the construction method of the refractory structure in one embodiment of the present invention. It is an exploded perspective view of the same fire-resistant structure explaining the external force which acts on the same fire-resistant structure at the time of normal. It is an exploded perspective view of the same fire-resistant structure explaining the external force which acts on the same fire-resistant structure at the time of a fire. It is a perspective view which shows the outline|summary of the analysis model of the fire-resistant structure of an Example. It is a perspective view which shows the outline|summary of the analysis model of the fire-resistant structure of a comparative example. It is a perspective view which shows an example of the simulation result of the fire-resistant structure of an Example. It is a perspective view which shows an example of the simulation result of the fireproof structure of a comparative example. FIG. 10 is a diagram showing an example of simulation results for determining changes in deflection with respect to combustion time; FIG. 10 is a diagram showing another example of simulation results of obtaining changes in deflection with respect to combustion time; It is a figure showing the change of deflection with respect to the change of (Ax(sigma) _y ).

An embodiment of a fire-resistant structure, a method for designing a fire-resistant structure, and a method for constructing a fire-resistant structure according to the present invention will be described below with reference to FIGS.
As shown in FIGS. 1 and 2, the fireproof structure 1 of this embodiment includes a floor 10, a plurality of fireproof covered beams 25, a plurality of fireproof covered columns 35, and a reduced fireproof covered beam 40. ing. In addition, in FIG. 1, the floor 10 is transparently shown. In the following figures, the columns and beams with the fireproof coating applied without reduction are shown hatched.
The floor 10 is flat. The floor 10 has a rectangular shape with a plurality of corners 10a when viewed in the thickness direction Z of the floor 10 . Note that the floor portion 10 may have a polygonal shape such as a triangular shape or a trapezoidal shape when viewed in the thickness direction Z.

In this embodiment, the floor 10 is arranged so that the thickness direction Z extends along the vertical direction. Note that the floor portion 10 may be arranged so that the thickness direction Z intersects with the vertical direction.
Here, a first cross direction X and a second cross direction Y are defined as directions that are orthogonal (cross) to each other on the upper surface (plane) of the floor portion 10 . The first cross direction X is the longitudinal direction of the floor 10 when viewed in the thickness direction Z. As shown in FIG. The second cross direction Y is the lateral direction of the floor 10 when viewed in the thickness direction Z. As shown in FIG.
Note that the first crossing direction X and the second crossing direction Y are not particularly limited as long as they cross each other within the upper surface of the floor section 10 .

As shown in FIG. 2, the floor 10 is a so-called reinforced concrete slab. The floor 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 dummy formwork for the concrete 12 and is designed so as not to exhibit a synthesizing effect with the concrete 12 .
The concrete 12 has the same shape as the floor 10 when viewed in the thickness direction Z. As shown in FIG. Concrete 12 is placed on deck plate 11 . Deck plate 11 and reinforcing bars 13 are provided in concrete 12 . The fact that the deck plate 11 and the reinforcing bars 13 are provided in the concrete 12 here means that the state in which the deck plate 11 and the reinforcing bars 13 are partly exposed from the concrete 12 is also included.

The configuration of the reinforcing bar 13 is not particularly limited as long as it has a first reinforcing bar extending along the first cross direction X and a second reinforcing bar extending along the second cross direction Y. As shown in FIGS. 2 and 3 , in this embodiment, the reinforcing bar 13 has a plurality of first reinforcing bars 15 and 16 and a plurality of second reinforcing bars 17 .
Note that FIG. 2 does not show a first connecting member 19, which will be described later.

Each first reinforcing bar 15, 16 extends along the first cross direction X, respectively. The first reinforcing bar 15 is arranged above the first reinforcing bar 16 . The first reinforcing bars 15 and 16 are arranged side by side in the thickness direction Z with an interval therebetween. The first reinforcing bars 15 and 16 extend to each end of the concrete 12 in the first cross direction X. As shown in FIG. The first reinforcing bars 15 and 16 transmit the tensile force between the ends of the concrete 12 (floor section 10) in the first cross direction X. As shown in FIG. As shown in FIG. 3 , the first reinforcing bars 15 and 16 are joined together by a first connecting member 19 . The first connecting member 19 has a zigzag shape that extends along the first cross direction X and alternately folds in the thickness direction Z. As shown in FIG.
Each second reinforcing bar 17 extends along the second cross direction Y. As shown in FIG. The second reinforcing bars 17 extend to each end of the concrete 12 in the second cross direction Y. As shown in FIG. The second reinforcing bars 17 transmit the tensile force between the ends of the concrete 12 in the second cross direction Y. As shown in FIG. The plurality of second reinforcing bars 17 are joined to the plurality of first reinforcing bars 15 by welding, wire mesh, or the like.
The plurality of first reinforcing bars 15 are joined together by a plurality of second connecting members 20 . Each second connecting member 20 has a zigzag shape that extends along the second cross direction Y and alternately folds in the thickness direction Z. As shown in FIG. A first reinforcing bar 15 is joined to the upper end of the mountain portion of the second connecting member 20 .

In this embodiment, the reinforcing bars 13 are embedded in the concrete 12 .
The number of the plurality of first reinforcing bars 15 and 16 and the number of the plurality of second reinforcing bars 17 included in the reinforcing bar 13 is not limited, and each number may be one.
Floor 10 may be a composite slab with rebar 13 , deck plate 11 and concrete 12 .

As shown in FIG. 1 , the plurality of coated fireproof beams 25 has a pair of first coated fireproof beams 26 and a pair of second coated fireproof beams 27 .
For example, the fire-resistant coated beams 26, 27 are H-beams with a fire-resistant coating. A heat insulating material such as rock wool or glass wool is used for the fireproof coating. In this case, the refractory coating is applied to this H-beam by a spraying method.

For example, the thickness of the fire-resistant coating such as rock wool on the fire-resistant coated beams 26 and 27 is set in accordance with the "Guidelines for Construction Quality Control of Fire-Resistant Structures Covered with Sprayed Rock Wool (Rock Wool Industry Association, Spraying Division)". If the fire-resistant coated beams 26 and 27 are required to be fire resistant for one hour, the thickness of the fire-resistant coating is set to 25 mm. Similarly, if the fire-resistant coated beams 26 and 27 are required to withstand fire for 2 hours, the thickness of the fire-resistant coating is set to 45 mm. When the fireproof coated beams 26 and 27 are required to withstand fire for 3 hours, the thickness of the fireproof coating is set to 60 mm.
In this specification, beams and columns with fireproof coating mean beams and columns with fireproof coating of this specification, for example.

The fireproof coating may be applied to the H-section steel by a winding method or a forming plate method. The fireproof coated beams 26 and 27 may be made of reinforced concrete (RC: Reinforced Concrete) or steel reinforced concrete (SRC: Steel Reinforced Concrete).
A pair of first refractory coated beams 26 extend along the first cross direction X. As shown in FIG. A pair of first fireproof coated beams 26 are spaced apart from each other in the second cross direction Y. As shown in FIG.
A pair of second fireproof coated beams 27 extend along the second cross direction Y. As shown in FIG. Between the first coated fireproof beam 26 and the second coated fireproof beam 27, a gap is formed in which the coated fireproof column 35 is arranged.

As shown in FIG. 2 , a shear force transmission member 28 such as a stud is fixed to the upper surface of the first fireproof coated beam 26 . The shear force transmission member 28 penetrates the deck plate 11 and is embedded in the concrete 12 . The first covered fireproof beam 26 supports the end of the floor 10 in the second cross direction Y from below the floor 10 . The first fireproof coated beam 26 is fixed (rigidly joined) to the floor 10 .
Although not shown, a shear force transmission member 28 is also fixed to the upper surface of the second fireproof covered beam 27 . The second fireproof covered beam 27 supports the end of the floor 10 in the first cross direction X from below the floor 10 . The first fireproof coated beam 26 is fixed to the floor 10 .
Thus, the fireproof coated beams 25 support the periphery of the floor 10 from below.

For example, the refractory cladding columns 35 are H-beams with refractory cladding.
As shown in FIG. 1, the multiple refractory coating columns 35 extend along the thickness direction Z. As shown in FIG. In this embodiment, the plurality of fireproof coating columns 35 are arranged below the plurality of corners 10a of the floor 10, respectively. The end portions of the plurality of fireproof covered beams 25 are rigidly joined to the upper end portions (parts) of the plurality of fireproof covered columns 35 . The upper ends of the plurality of fire-resistant covering columns 35 and the plurality of fire-resistant covering beams 25 are formed in an angular annular shape as a whole. That is, the region R1 is surrounded by the upper end portions of the plurality of covered fireproof beams 25 and the plurality of covered fireproof columns 35 .
Note that the fire-resistant coated column may be a fire-resistant square steel pipe or a fire-resistant circular steel pipe. In addition, the fireproof cladding column may be of concrete filled steel tube construction, reinforced concrete construction, or steel reinforced concrete construction.
In this embodiment, the fire resistant structure 1 comprises a plurality of reduced fire resistant coated beams 40 .

As shown in FIG. 2, in this embodiment, the reduced fire resistant coated beam 40 is a weld assembled H-beam 42 with a fire resistant coating 41 applied. However, the reduced fire resistant coated beam 40 has less fire resistant coating than the fire resistant coated beam 25 does. A plurality of fire-resistant coated beams 40 are arranged in the region R1, and both ends thereof are joined to a plurality of fire-resistant coated beams 25 by pin joints. For example, the pin connection is performed by fastening the gusset plate welded to the fire resistant coated beam 25 and the reduced fire resistant coated beam 40 with high strength bolts or the like. Both ends of the plurality of fire resistant coated beams 40 may be joined to the fire resistant coated beams 25 by rigid joints or semi-rigid joints. The definitions of pinned, semi-rigid and rigid joints shall in particular comply with the European Design Code (Eurocode 3 Part 1-8).

The welded assembled H-section steel 42 has a web 44 and a pair of flanges 45 arranged to sandwich the web 44 . The thickness of the web 44 is preferably 4.5 mm or more and 7.5 mm or less, and the thickness of the flange 45 is preferably 5.5 mm or more and 9 mm or less. The thickness of the weld assembled H-section steel 42 is preferably 500 mm or more and 700 mm or less, and the width of the weld assembly H-section steel 42 is preferably 115 mm or more and 200 mm or less.
Weld-assembled H-beam 42 is manufactured by welding a web 44 and a pair of flanges 45 together.

As shown in FIG. 1, the plurality of coated beams 40 with reduced fire resistance extend in the second cross direction Y and are spaced apart in the first cross direction X. As shown in FIG.
Although not shown, the shear force transmission members 28 are also fixed to the upper surfaces of the multiple reduced fire resistant coated beams 40 . A plurality of fire resistant covered beams 40 support the floor 10 from below. The multiple reduced fire resistant covered beams 40 are fixed (rigidly joined) to the floor 10 . In this way, the plurality of fire resistant covered beams 40 support the floor 10 from below.

The yield strength σ _y at room temperature of the weld assembled H-section steel of the reduced fire resistant coated beam 40 is 235 N/mm ² or more.
FIG. 4 shows an example of changes in yield strength with respect to temperature in steel. In FIG. 4, the horizontal axis represents temperature (° C.) and the vertical axis represents yield strength (N/mm ² . Newtons per square millimeter). In FIG. 4, the change in tensile strength 400 N/mm grade ² steel is represented by line L1. The change in tensile strength 590 N/mm class ² steel is represented by line L2. Regardless of the value of tensile strength, the yield strength is substantially constant from room temperature to a predetermined temperature, but when the temperature exceeds the predetermined temperature, the yield strength gradually decreases as the temperature increases.
In the range from room temperature to the predetermined temperature, the 590 N/mm class ² tensile strength steel has a higher yield strength than the 400 N/mm class ² tensile strength steel. Even if the temperature exceeds the predetermined temperature, the tensile strength class ² steel of 590 N/mm is considered to have a higher yield strength than the tensile strength class ² steel of 400 N/mm.

The yield strength σ _y is preferably 295 N/mm ² or more. When the yield strength σ _y satisfies this condition, it is possible to satisfy the design standard strength assumed for the welded assembly H-section steel for small beams.
This yield strength σ _y is more preferably 325 N/mm ² or more. When the yield strength σ _y satisfies this condition, the steel material has a tensile strength equivalent to 50K and is equivalent to SN490 defined in JIS G 3136 Rolled steel for building construction.
This yield strength σ _y is more preferably 385 N/mm ² or more. When the yield strength σ _y satisfies this condition, a 550 MPa class high-strength steel sheet can be obtained.

When setting the thickness of the fireproof coating on the fireproof coated beams 25 in accordance with the "Guidelines for Construction Quality Control of Fireproof Structures Covered with Spraying Rock Wool", the thickness of the fireproof coating on the reduced fireproof coated beams 40 is set to the thickness of each fireproof The thickness is about 1/10 to 1/2 of the fireproof coating thickness of the fireproof coated beam 25 depending on the performance.
It should be noted that the number of the reduced fire resistant covered beams 40 included in the fire resistant structure 1 may be one.

Next, a fire-resistant structure designing method (hereinafter simply referred to as a designing method) of the present embodiment for designing the fire-resistant structure 1 configured as described above will be described. FIG. 5 is a flowchart showing design method S10 in one embodiment of the present invention.
First, in the structure setting step (step S11 shown in FIG. 5), by performing known structural calculations, as shown in FIG. The arrangement of the portion 10, the plurality of beams 50, and the plurality of pillars 51 is set. A plurality of beams 50 support the floor 10 from below. The multiple pillars 51 are joined to the multiple beams 50 . The upper end portions of the multiple columns 51 and the multiple beams 50 are formed in an angular annular shape as a whole.
When the structure setting step S11 ends, the process proceeds to step S13.

Next, in the first fire-resistant specification setting step (step S13), the periphery of the floor 10 is supported from below by a plurality of fire-resistant coated beams 25 obtained by coating the beams 50A, which are part of the plurality of beams 50, with a fire-resistant coating. (see Figure 1).
After completion of the first fireproof specification setting step S13, the process proceeds to step S15.
Next, in a second fireproof specification setting step (step S15), fireproof coating is applied to the multiple columns 51 to set the multiple fireproof coated columns 35 (see FIG. 1).
When the second fireproof specification setting step S15 ends, the process proceeds to step S17.

Next, in the third fire-resistant specification setting step (step S17), a plurality of reduced fire-resistant coated beams 40 obtained by applying a fire-resistant coating to the beams 50B, which are the remaining portions of the plurality of beams 50, are arranged in the region R1 (see FIG. 1 ). Further, the end portions of the beams 40 covered with reduced fire resistance are joined to the covered beams 25 with reduced fire resistance so that the plurality of beams 40 covered with reduced fire resistance support the floor 10 from below.
When the third refractory specification setting step S17 is completed, all the steps of the design method S10 are completed, and the refractory structure 1 is designed.
The reduced fire resistant coated beam 40 of the fire resistant structure 1 may not be coated with a fire resistant coating. In this case, in the third fireproof specification setting step S17, the plurality of beams 50B, which are the rest of the plurality of beams 50, are arranged within the region R1.

Next, a fire-resistant structure construction method (hereinafter simply referred to as a construction method) of the present embodiment for constructing the fire-resistant structure 1 will be described. FIG. 7 is a flow chart showing the construction method S20 in one embodiment of the invention.
First, in the column-to-beam construction process (step S21 shown in FIG. 7), the foundation structure 1A including the floor section 10, the plurality of beams 50, and the plurality of columns 51 is constructed. A plurality of beams 50 support the floor 10 from below. The multiple pillars 51 are joined to the multiple beams 50 .
After completion of the column and beam construction process S21, the process proceeds to step S23.

Next, in the first covering step (step S23), the periphery of the floor 10 is supported from below by a plurality of fire-resistant coated beams 25 obtained by coating the beams 50A, which are part of the plurality of beams 50, with a fire-resistant coating.
When the first covering step S23 ends, the process proceeds to step S25.
Next, in a second covering step (step S25), the plurality of columns 51 are coated with a fireproof coating to form a plurality of fireproof coated columns 35. As shown in FIG.
When the second covering step S25 ends, the process proceeds to step S27.

Next, in the third covering step (step S27), a plurality of beams 40 with reduced fire resistance coating, which are beams 50B, which are the remainder of the plurality of beams 50, with fire resistance coating are arranged in the region R1. Furthermore, the ends of the fireproof coated beams 40 are joined to the fireproof coated beams 25 to support the floor 10 from below.
When the third covering step S27 is finished, all the steps of the construction method S20 are finished, and the refractory structure 1 is constructed.
The reduced fire resistant coated beam 40 of the fire resistant structure 1 may not be coated with a fire resistant coating. In this case, in the third covering step S27, the plurality of beams 50B, which are the remainder of the plurality of beams 50, are arranged within the region R1.

Here, the deformation of the floor 10 and the like due to the membrane effect before and after a fire will be schematically described.
FIG. 8 shows an exploded perspective view of the fire-resistant structure 1 during normal times when no fire has occurred. In addition, in FIG. 8 and FIG. 9 which will be described later, the refractory structure 1 is shown in a simplified manner.
In the normal state shown in FIG. 8, a downward external force F1 acts on the floor 10, the beams 40 covered with reduced fire resistance, and the like due to gravity, static load, and the like acting on the floor 10, the beams 40 covered with reduced fire resistance, and the like.
On the other hand, in the event of a fire, as shown in FIG. 9, the central portion of the floor portion 10 in a plan view bends so as to protrude downward. However, due to the so-called membrane effect, the circumference of the floor 10 is supported by the upper end portions of the plurality of fireproof coated beams 25 and the plurality of fireproof coated columns 35 which are formed in an annular shape as a whole. The first reinforcing bars 15 and 16 extended by the bending of the floor 10 transmit the tensile force F2 in the first cross direction X. As shown in FIG. The second reinforcing bar 17 extended by the bending of the floor 10 transmits the tensile force F3 in the second cross direction Y. As shown in FIG. That is, the floor 10 resists the gravity acting on the floor 10 by the tensile forces F2 and F3.
Therefore, the central portion of the floor 10 is supported by the plurality of fireproof covered beams 25, the upper ends of the plurality of fireproof covered columns 35, the first reinforcing bars 15, 16, and the second reinforcing bars 17 in the first crossing direction X and the second crossing direction. They are supported in direction Y, respectively.

At this time, a tension region R5 and a compression region R6 are formed in the floor portion 10, respectively. Note that the compressed region R6 is indicated by hatching in FIG. In the pulling region R5, the floor 10 is pulled along the bent upper surface. In the compression region R6, the floor 10 is compressed along the bent upper surface.
The tension region R5 is formed in the central portion of the floor 10 in plan view. A compression region R6 is formed around the tension region R5.
The membrane effect that occurs in the refractory structure 1 during fire is the effect of resisting the tensile forces F2 and F3 by the reinforcing bars 13. FIG.

As described above, in the design method S10 of the present embodiment, the arrangement of the floor 10, the plurality of beams 50, and the plurality of columns 51 is set in the structure setting step S11. Next, in the first fireproof specification setting step S13, the periphery of the floor section 10 is set to be supported from below by a plurality of fireproof coated beams 25 in which a portion of the plurality of beams 50 is coated with a fireproof coating. Next, in a second fireproof specification setting step S<b>15 , fireproof coating is applied to the multiple columns 51 to set the multiple fireproof coated columns 35 . Next, in the third fire resistance specification setting step S17, the plurality of reduced fire resistance coated beams 40 in which the remaining portions of the plurality of beams 50 are coated with fire resistance are surrounded by the plurality of fire resistance covered beams 25 and the plurality of fire resistant covered columns 35. While being arranged within the region R1, the end portions of the plurality of fire-resistant covered beams 40 are joined to the fire-resistant covered beams 25 to support the floor section 10 from below.
The refractory structure 1 is designed by performing the above steps.

In the fire-resistant structure 1 designed as described above, a plurality of annularly formed fire-resistant covered beams 25 and a plurality of fire-resistant covered columns 35 that can maintain constant rigidity and strength even in the event of a fire surround the floor 10. is supported from below by the upper end of the The reinforcing bars 13 provided in the floor 10 transmit the tensile force between the ends of the floor 10 in the first cross direction X and the tensile force between the ends of the floor 10 in the second cross direction Y. do. In the event of a fire, gravity or the like acting on the floor section 10 bends the central portion of the floor section 10 in plan view so as to protrude downward. However, due to the membrane effect, the circumference of the floor 10 is supported by the upper ends of the multiple fireproof coated beams 25 and the multiple fireproof coated columns 35 . As the floor 10 bends, the reinforcing bars 13 extend and transmit tensile forces in the first cross direction X and the second cross direction Y, respectively, so that the central portion of the floor 10 is supported. Therefore, the fireproof performance of the fireproof structure 1 can be maintained at the same level as the conventional one.

Furthermore, since the reduced fire-resistant coated beam 40 has the welded assembled H-section steel 42, the thickness of the web and flange constituting the H-section steel is greater than when the H-shaped steel of the reduced fire-resistant coated beam is a rolled H-section steel. etc. can be set more freely. Therefore, for example, the cross-sectional area perpendicular to the longitudinal direction and the yield strength at normal temperature in the welded assembly H-section steel 42 are more than the product of the cross-sectional area perpendicular to the longitudinal direction and the yield strength at room temperature in a small beam of conventional H-section steel construction. The fire resistance performance of the fire resistant structure 1 can be improved by increasing the product with the strength.

The yield strength σ _y of the welded assembled H-section steel 42 of the reduced fire resistant coated beam 40 is 235 N/mm ² or more. Therefore, the strength of the coated beam 40 with reduced fire resistance can be ensured to be higher than the standard strength of H-section steel. Even if the webs 44 and flanges 45 of the welded H-section steel 42 are made thinner, the welded H-section steel 42 can maintain a certain strength.
The floor 10 is a reinforced concrete slab. Since reinforced concrete slabs are widely used as floors, the floor 10 can be designed (configured) at low cost.

The reinforcing bar 13 has a plurality of first reinforcing bars 15 and 16 and a plurality of second reinforcing bars 17 . Therefore, with a simple configuration of the plurality of first reinforcing bars 15 and 16 and the plurality of second reinforcing bars 17, the tensile force F2 between the ends of the floor 10 in the first crossing direction X and the second crossing of the floor 10 A tensile force F3 between the ends in direction Y can be transmitted respectively.
The fire-resistant coated beams 25 are H-section steel with fire-resistant coating. Since H-section steel is widely used as a beam, the fireproof coated beam 25 can be designed at low cost.

The fireproof coated columns 35 are H-section steel with fireproof coating. Since H-section steel is widely used for columns, the fireproof coating column 35 can be designed at low cost.
Refractory coatings are applied to H-beams by a winding method. Since the winding method is widely used to apply a fire-resistant coating to H-shaped steel or the like, the fire-resistant coating can be applied at a low cost.

Further, in the construction method S20 of the present embodiment, the floor section 10, the plurality of beams 50, and the plurality of columns 51 are constructed in the beam-column construction step S21. Next, in a first covering step S23, the periphery of the floor 10 is supported from below by a plurality of fire-resistant coated beams 25 obtained by coating a portion of the plurality of beams 50 with a fire-resistant coating. Next, in a second coating step S25, the multiple columns 51 are coated with a fireproof coating to form multiple fireproof coated columns 35. As shown in FIG. Next, in a third covering step S27, a plurality of reduced fire-resistant coated beams 40 in which the remaining portions of the plurality of beams 50 are coated with a fire-resistant coating are placed in a region R1 surrounded by a plurality of fire-resistant coated beams 25 and a plurality of fire-resistant coated columns 35. The floor 10 is supported from below by joining the end portions of the plurality of fire-resistant coated beams 40 to the fire-resistant coated beams 25 .
The refractory structure 1 is constructed by performing the above steps.

In the fire-resistant structure 1 constructed as described above, a plurality of annularly formed fire-resistant covered beams 25 and a plurality of fire-resistant covered columns 35 that can maintain constant rigidity and strength even in the event of a fire surround the floor 10. is supported from below by the upper end of the The reinforcing bars 13 provided in the floor 10 transmit the tensile force between the ends of the floor 10 in the first cross direction X and the tensile force between the ends of the floor 10 in the second cross direction Y. do. In the event of a fire, gravity or the like acting on the floor section 10 bends the central portion of the floor section 10 in plan view so as to protrude downward. However, due to the membrane effect, the circumference of the floor 10 is supported by the upper ends of the multiple fireproof coated beams 25 and the multiple fireproof coated columns 35 . As the floor 10 bends, the reinforcing bars 13 extend and transmit tensile forces in the first cross direction X and the second cross direction Y, respectively, so that the central portion of the floor 10 is supported. Therefore, the fireproof performance of the fireproof structure 1 can be maintained at the same level as the conventional one.

Furthermore, since the reduced fire-resistant coated beam 40 has the welded assembled H-section steel 42, the thickness of the web and flange constituting the H-section steel is greater than when the H-shaped steel of the reduced fire-resistant coated beam is a rolled H-section steel. etc. can be set more freely. Thus, for example, the web 44 of the weld-assembled H-beam 42 is made thinner than the web thickness conventionally used for H-beam girders, and the weld-fabricated H-beam 44 is thinner than that of the H-beam girders. By increasing the thickness of the shaped steel 42, the fire resistance performance of the fire resistant structure 1 can be improved.

In addition, in the fire-resistant structure 1 of the present embodiment, the circumference of the floor 10 is a plurality of fire-resistant covered beams 25 and a plurality of fire-resistant covered columns 35 formed in an annular shape, which can maintain constant rigidity and strength even in the event of a fire. It is supported from below by the upper end. The reinforcing bars 13 provided in the floor 10 transmit the tensile force between the ends of the floor 10 in the first cross direction X and the tensile force between the ends of the floor 10 in the second cross direction Y. do. In the event of a fire, gravity or the like acting on the floor 10 bends the central portion of the floor 10 in plan view so as to project downward. However, due to the membrane effect, the perimeter of the floor 10 is supported by the upper ends of the plurality of fireproof coated beams 25 and the plurality of fireproof coated columns 35 . The central portion of the floor portion 10 is supported by the reinforcing bars 13 extended by the bending of the floor portion 10 transmitting tensile forces in the first cross direction X and the second cross direction Y, respectively. Therefore, the fireproof performance of the fireproof structure 1 can be maintained at the same level as the conventional one.

Furthermore, since the reduced fire-resistant coated beam 40 has the welded assembled H-section steel 42, the thickness of the web and flange constituting the H-section steel is greater than when the H-shaped steel of the reduced fire-resistant coated beam is a rolled H-section steel. etc. can be set more freely. Therefore, for example, the cross-sectional area perpendicular to the longitudinal direction and the yield strength at normal temperature in the welded assembly H-section steel 42 are more than the product of the cross-sectional area perpendicular to the longitudinal direction and the yield strength at room temperature in a small beam of conventional H-section steel construction. By increasing the product with the strength, the fire resistance performance of the fire resistant structure 1 can be improved.

(simulation result)
Here, the result of examining the fire resistance performance of the fire resistant structures of Examples and Comparative Examples by simulation will be described.

(1. Investigation to equalize the moment of inertia of area)
FIG. 10 shows the outline of the analysis model of the fire-resistant structure 1B of the example. In FIG. 10 and FIG. 11, which will be described later, a solid line indicates a beam without the fireproof coating removed, and a dotted line indicates a beam with the fireproof cover removed. In addition, the floor part 10 is not shown in FIG.10 and FIG.11.
The cross-sectional dimensions of the H-shaped steel of the fire-resistant coated beams 26 and 27 were H-1000×400×19×28. As shown in FIG. 10, with respect to the upper end of each refractory cladding column 35, the refractory cladding beams 26, 27 can rotate about a first cross direction X, a second cross direction Y, and a thickness direction Z, respectively. and
The fireproof covering beams 26 and 27 are fixed in the first cross direction X, the second cross direction Y, and the thickness direction Z to the fireproof covering column 35A, which is one of the plurality of fireproof covering columns 35. and Among the plurality of fireproof covered columns 35, the fireproof covered beams 26 and 27 are arranged in the first cross direction X, the second cross direction Y, and the thickness direction Z with respect to the fireproof covered column 35B other than the fireproof covered column 35A. I thought I could move.

The length L5 of the first fireproof coated beam 26 was 19,200 mm. The length L6 of the second fireproof coated beam 27 was 7,200 mm.
The reduced fire resistant coated beam 40A is a beam to which the reduced fire resistant coated beam 40 is not coated with any fire resistant coating. Table 1 shows the cross-sectional dimensions of the welded assembly H-section steel 42 of the reduced fire resistant coated beam 40A.

The cross-sectional dimensions of the welded assembly H-section steel 42 were 700×175×4.5×9. The yield strength of the welded assembled H-section steel 42 was 440 N/mm ² . The geometric moment of inertia of the welded assembled H-section steel 42 is 49,500 cm ⁴ . The mass per unit length of the welded assembled H-section steel 42 is 48.8 kg/m.
A description of the specifications of the floor 10 used in the refractory structure 1B is omitted.
In FIG. 10, the direction (first intersecting direction X) in which the first reinforcing bars 15 and 16 extend is shown as the direction W of the main bars.
The thickness of the floor portion 10 was set to 140 mm. The first reinforcing bars 15 and 16 were D13@200. The second reinforcing bar 17 was D10@150. The fireproof coating thickness of the fireproof coated beams 26 and 27 was set to 45 mm.

On the other hand, the fire-resistant structure 2 of the comparative example shown in FIG. 11 includes a plurality of reduced fire-resistant covered beams 55 instead of the plurality of reduced fire-resistant covered beams 40A of the fire-resistant structure 1B of the example. The H-section steel of the reduced fire resistant coated beam 55 is the rolled H-section steel 56 . The cross-sectional dimensions of the rolled H-section steel 56 were, as shown in Table 1, 500×200×10×16. The yield strength of the rolled H-section steel 56 was 235 N/mm ² . The rolled H-section steel 56 is not provided with any refractory coating. The area moment of inertia of the rolled H-section steel 56 is 48,800 cm ⁴ . The mass per unit length of the rolled H-section steel 56 is 88.2 kg/m.

At this time, the height ratio of the weld assembled H-section steel 42 to the height of the rolled H-section steel 56 is 1.40. The ratio of the geometrical moment of inertia of the welded assembled H-section steel 42 to the geometrical moment of inertia of the rolled H-section steel 56 is 1.01. That is, the area moment of inertia of the rolled H-section steel 56 and the area moment of inertia of the welded H-section steel 42 are equivalent to each other.
The ratio of the mass of weld assembled H-beam 42 to the mass of rolled H-beam 56 is 0.55. That is, the weld assembled H-section steel 42 has the same geometrical moment of inertia as the rolled H-section steel 56, but has about half the mass.
In the design of beams used at room temperature, we generally focus on the geometrical moment of inertia of the beam. In this simulation, in a state where the geometrical moment of inertia of the H-section steels 42 and 56 of the H-shaped steels 42 and 56 of the reduced fire-resistant coated beams 40A and 55 of the fire-resistant structures 1B and 2 of the example and the comparative example are made equal, Compare fire resistance performance.

It was assumed that the refractory structures 1B, 2 were heated for 120 minutes (2 hours) based on the standard heating curve specified in ISO 834-11:2014. In general, members such as beams and columns become longer as the temperature rises. Through simulation, the relationship between the temperature of the member and the time when heated based on the standard heating curve was obtained in advance. After that, based on the relationship obtained in advance, deflection due to thermal expansion, strength, and reduction in rigidity of the member with respect to time from the start of combustion (heating) was obtained. The deflection is the deflection at the center P1 (see FIGS. 10 and 11) of the floor 10 in a plan view.

The total strain is represented by the sum of mechanical strain and thermal strain.
A condition for terminating the simulation is, for example, that the mechanical strain at the ends of the H-beams 42, 56 exceeds a threshold value such as 20%. The reason why the conditions for termination are determined in this way is that among the H-section steels 42 and 56, the strain at the ends is the largest.

FIG. 12 shows an example of the deflection state in the simulation result of the fire-resistant structure 1B. The shape of the refractory structure 1B before heating is indicated by a chain double-dashed line. It was found that the refractory structure 1B could support a vertical load even after 120 minutes from the start of combustion.
FIG. 13 shows an example of the deflection state in the simulation results of the fire-resistant structure 2. In FIG. The simulation was terminated 94 minutes after the start of heating because the mechanical strain at the end of the reduced refractory coated beam 55 placed in the center of the first cross direction X exceeded the threshold.

FIG. 14 shows the result of obtaining the change in deflection at the center P1 with respect to the combustion time of the refractory structures 1B and 2. As shown in FIG. In FIG. 14, the horizontal axis represents combustion time (minutes) and the vertical axis represents deflection (mm). A solid line L9 represents the deflection of the refractory structure 1B, and a dotted line L10 represents the deflection of the refractory structure 2. FIG.
It can be seen that compared to the fire-resistant structure 2, the fire-resistant structure 1B can withstand combustion for a long period of time, and the deflection at the center P1 at each time is smaller. As a result, it was found that the fire-resistant structure 1B can improve the fire-resistant performance compared to the fire-resistant structure 2.

(2. Examination focusing on the product of cross-sectional area and yield strength of H-shaped steel)
In (1.), it was considered that the moment of inertia of area is unlikely to become a dominant parameter of fire resistance performance. Therefore, we investigated the parameters that contribute to the fire resistance performance.
As shown in Table 2, the yield strength σ _y is changed to 235 N/mm ² , 325 N/mm ² and 440 N/mm ² for the H-section steels 42 and 56 of the refractory structures 1B and 2, from case 1 A parametric study of case 6 was performed.

The simulation results in (1.) correspond to cases 2 and 5.
A cross-sectional area A perpendicular to the longitudinal direction of the welded assembly H-section steel 42 is 6,219 mm ² . A cross-sectional area A perpendicular to the longitudinal direction of the rolled H-section steel 56 is 11,230 mm ² .
The product (A×σ _y ) of the cross-sectional area A and the yield strength σ _y of the H-section steels 42 and 56 is hereinafter also referred to as yield axial force.
FIG. 15 shows the results of obtaining changes in deflection at the center P1 with respect to the combustion times of Cases 1 to 6. In FIG. In FIG. 15, the horizontal axis represents combustion time (minutes) and the vertical axis represents deflection (mm). Lines L21 through L26 represent the results of cases 1 through 6, respectively.
For example, in FIG. 15, Table 3 and FIG. 16 show the deflection obtained in each case when the heating time is 60 minutes. FIG. 16 is a graph showing trends for Cases 1, 3, and 5, which are examples.

In FIG. 16, the horizontal axis represents (A×σ _y )(kN), and the vertical axis represents deflection at center P1. It can be seen that the deflection decreases as the yield axial force (A×σ _y ) increases. The deflection has a substantially linear relationship with the yield axial force (A×σ _y ). At this time, the relationship between the deflection δ (mm) and the yield axial force (A×σ _y ) is given by Equation (1).
δ=−0.0793×(A×σ _y )+572.68 (1)
The yield axial force (A×σ _y ) is preferably 1000 kN (kilonewton) or more and 6000 kN or less. More preferably, the yield axial force (A×σ _y ) is 1000 kN or more and 3000 kN or less.
The specifications of the H-section steels 42 and 56 with improved fire resistance can be applied to the fire-resistant structures 1B and 2 because the yield axial force is 1000 kN or more and 6000 kN or less.

As described above, one embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and the configuration can be changed, combined, or deleted without departing from the scope of the present invention. etc. are also included.

REFERENCE SIGNS LIST 1 refractory structure 10 floor 11 deck plate 12 concrete 13 reinforcing bar (tensile force transmission member)
15, 16 First reinforcing bar 17 Second reinforcing bar 25 Fire resistant coated beam 35 Fire resistant coated column 40 Reduced fire resistant coated beam 41 Fire resistant coating 42 Welding assembled H-beam 50 Beam 51 Column R1 Area S10 Design method (design method of fire resistant structure)
S11 Structural setting step S13 First fireproof specification setting step S15 Second fireproof specification setting step S17 Third fireproof specification setting step S20 Construction method (fireproof structure construction method)
S21 Column and beam construction process S23 First covering process S25 Second covering process S27 Third covering process X First cross direction Y Second cross direction

Claims (10)

a floor portion provided with a tensile force transmission member in concrete;
a plurality of refractory-coated beams that support the perimeter of the floor from below;
a plurality of fire-resistant coated columns that are coated with a fire-resistant coating and joined to the ends of the plurality of fire-resistant coated beams so that a portion of the columns and the plurality of fire-resistant coated beams are formed in an annular shape as a whole;
Welded assembled H-section steel, wherein the fireproof coating is reduced more than the fireproof coated beam, is arranged in an area surrounded by the plurality of fireproof coated beams and the plurality of fireproof coated columns, and the ends are located in the plurality of a reduced fireproof coated beam that is joined to the fireproof coated beam and supports the floor from below;
with
When the directions intersecting each other in the plane of the floor are defined as a first crossing direction and a second crossing direction,
The tensile force transmission member is a refractory structure that transmits the tensile force between the ends of the floor in the first cross direction and the tensile force between the ends of the floor in the second cross direction. A design method for a fire-resistant structure to be designed,
a structure 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 calculation;
a first fireproof specification setting step of setting the periphery of the floor so as to be supported from below by the plurality of fireproof coated beams in which a portion of the plurality of beams is coated with fireproof;
a second fireproof specification setting step of applying a fireproof coating to the plurality of pillars and setting the fireproof coating to the plurality of fireproof coated pillars;
The reduced fire-resistant coated beams that are the remaining portions of the plurality of beams, or the reduced fire-resistant coated beams obtained by applying fire-resistant coating to the remaining portions of the plurality of beams, are arranged in the region, and the ends of the reduced fire-resistant coated beams a third fireproof specification setting step of setting to support the floor from below by joining to the fireproof coated beam;
method of designing fire-resistant structures. 2. The method of designing a fire-resistant structure according to claim 1, wherein the welded H-section steel of the reduced fire-resistant coated beam has a yield strength of 235 N/ ^mm2 or more at room temperature. The product of the cross-sectional area (mm ² ) perpendicular to the longitudinal direction of the weld assembled H-section steel and the yield strength (N/mm ² ) of the weld assembled H-section steel at room temperature is 1000 kN or more and 6000 kN or less. Item 3. A method for designing a fire-resistant structure according to Item 1 or 2. The method for designing a fire-resistant structure according to any one of claims 1 to 3, wherein the floor is a composite slab or a reinforced concrete slab. The tensile force transmission member is
a first reinforcing bar extending along the first cross direction and transmitting tensile force between ends of the floor in the first cross direction;
5. The fire resistance according to any one of claims 1 to 4, further comprising a second reinforcing bar extending along the second cross direction and transmitting a tensile force between ends of the floor in the second cross direction. How to design structures. The method for designing a fire-resistant structure according to any one of claims 1 to 5, wherein the fire-resistant coated beam is H-shaped steel, reinforced concrete, or steel-reinforced concrete with the fire-resistant coating applied. The fire-resistant coated column is made of H-shaped steel with the fire-resistant coating, square steel pipe with the fire-resistant coating, circular steel pipe with the fire-resistant coating, concrete-filled steel pipe, reinforced concrete, or steel-reinforced concrete. A method for designing a fire-resistant structure according to any one of claims 1 to 6. The method for designing a fire-resistant structure according to any one of claims 1 to 7, wherein the fire-resistant coating is applied by a spraying method, a molded plate method, or a winding method. a floor portion provided with a tensile force transmission member in concrete;
a plurality of refractory-coated beams that support the perimeter of the floor from below;
a plurality of fire-resistant coated columns that are coated with a fire-resistant coating and joined to the ends of the plurality of fire-resistant coated beams so that a portion of the columns and the plurality of fire-resistant coated beams are formed in an annular shape as a whole;
Welded assembled H-section steel, wherein the fireproof coating is reduced more than the fireproof coated beam, is arranged in an area surrounded by the plurality of fireproof coated beams and the plurality of fireproof coated columns, and the ends are located in the plurality of a reduced fireproof coated beam that is joined to the fireproof coated beam and supports the floor from below;
with
When the directions intersecting each other in the plane of the floor are defined as a first crossing direction and a second crossing direction,
The tensile force transmission member is a refractory structure that transmits the tensile force between the ends of the floor in the first cross direction and the tensile force between the ends of the floor in the second cross direction. A construction method for a refractory structure to be constructed,
a column and beam construction step of constructing the floor, a plurality of beams supporting the floor from below, and a plurality of columns joined to the plurality of beams;
a first covering step of supporting the periphery of the floor from below by the plurality of fire-resistant coated beams in which a part of the plurality of beams is coated with fire-resistant;
a second coating step of applying a fire resistant coating to the plurality of pillars to form the plurality of fire resistant coated pillars;
The reduced fire-resistant coated beams that are the remaining portions of the plurality of beams, or the reduced fire-resistant coated beams obtained by applying fire-resistant coating to the remaining portions of the plurality of beams, are arranged in the region, and the ends of the reduced fire-resistant coated beams a third coating step of joining the fireproof coated beam to support the floor from below;
A method of construction of a fire-resistant structure. a floor portion provided with a tensile force transmission member in concrete;
a plurality of refractory-coated beams that support the perimeter of the floor from below;
a plurality of fire-resistant coated columns that are coated with a fire-resistant coating and joined to the ends of the plurality of fire-resistant coated beams so that a portion of the columns and the plurality of fire-resistant coated beams are formed in an annular shape as a whole;
Welded assembled H-section steel, wherein the fireproof coating is reduced more than the fireproof coated beam, is arranged in an area surrounded by the plurality of fireproof coated beams and the plurality of fireproof coated columns, and the ends are located in the plurality of a reduced fireproof coated beam that is joined to the fireproof coated beam and supports the floor from below;
with
When the directions intersecting each other in the plane of the floor are defined as a first crossing direction and a second crossing direction,
The tensile force transmission member transmits a tensile force between the ends of the floor in the first crossing direction and a tensile force between the ends of the floor in the second crossing direction, respectively. .

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