JP2021011743A - Fire resistant structure - Google Patents

Abstract

To provide a fire resistant structure capable of further securely protecting a structural member against heat in a fire disaster.SOLUTION: A fire resistant structure 1 is for columns 10 constituting a building. An outer peripheral surface of a column 10 is covered with a non-inflammable thin plate 40, and an air layer 30 is provided between the column 10 and a non-inflammable thin plate 40. This constitution can suppress, even when a finished material 50 burns around the column 10 in a fire disaster, heat of the fire from reaching the column 10 with the thin plate 40 and the air layer 30 to further securely protect the column 10 against the heat in the fire disaster.SELECTED DRAWING: Figure 1

Description

The present invention relates to a fireproof structure of structural members such as columns and beams constituting a building.

Conventionally, the following structures have been proposed in order to protect structural members such as columns and beams constituting a building from heat during a fire (see Patent Document 1).
Patent Document 1 discloses a structure in which a steel frame member constituting a skeleton beam or a skeleton column of a building is surrounded by a plurality of fireproof coating materials.
In Patent Document 2, a core material made of wood material, an air layer provided outside the core material, an endothermic and heat insulating inorganic material provided outside the air layer, and an outside of the inorganic material are provided. A wood-based structural member comprising a fire-resistant coating material and a finishing material provided on the outside of the fire-resistant coating material is shown.
In Patent Document 3, a refractory material layer formed of a foamable refractory coating material, an air layer, and a burning allowance wood layer made of wood are laminated in order from the outside around a wood load support portion. Wood fireproof members are shown.

Japanese Unexamined Patent Publication No. 2013-87464 JP-A-2017-179889 JP-A-2018-145654

An object of the present invention is to provide a fireproof structure capable of more reliably protecting structural members from heat during a fire.

The present inventor covers structural members such as columns and beams with a non-combustible thin plate, and provides an air layer between the structural member and the non-combustible thin plate, so that the non-combustible thin plate allows the heat of combustion from combustible materials in the event of a fire to be generated by the structural member. We came to the present invention by focusing on the point that it can suppress the transmission to the air (radiation reduction effect).
The fire-resistant structure of the first invention (for example, the fire-resistant structures 1, 1A, 1B described later) includes a structural member (for example, a pillar 10 described later) constituting the building and a non-combustible thin plate (for example, described later) covering the structural member. Non-combustible thin plates 40, 40A, 40B), and an air layer (for example, air layers 30, 30A described later) is provided between the structural member and the non-combustible thin plate.

Here, examples of the non-combustible thin plate include a steel plate, a mortar plate, a calcium silicate plate, a stainless steel plate, a ceramic fiber cloth, a galvalume steel plate (registered trademark), and a galvanized steel plate.
According to the present invention, since the outer peripheral surface of structural members such as pillars and beams constituting the building is covered with an air layer and a non-combustible thin plate, even if combustible materials burn around the structural member in the event of a fire, the non-combustible thin plate And the air layer suppresses the heat of the fire from being transferred to the structural member (radiation reduction effect), and the structural member can be more reliably protected from the heat of the fire.

In the fireproof structure of the second invention, a fireproof coating material (for example, the fireproof coating material 20 described later) is provided on the outer surface of the structural member, and the air layer is composed of the fireproof coating material and the noncombustible thin plate. It is characterized in that it is provided between them.

Here, examples of the fireproof coating material include sprayed rock wool, foamable fireproof paint, mortar plate, and wrapping type rock wool felt.
According to the present invention, since the fireproof coating material is provided on the outer surface of the structural member, the structural member can be more reliably protected from the heat at the time of fire.

In the fireproof structure of the third invention, the air layer is provided with a support member (for example, a support member 11 described later) extending along the axial direction of the structural member, and the non-combustible thin plate is outside the support member. It is characterized by being attached to the surface.

According to the present invention, since the support member extending along the axial direction of the structural member is provided in the air layer, the non-combustible thin plate can be reliably supported while securing the air layer between the refractory coating material and the non-combustible thin plate. .. Therefore, even if the combustible material on the outside of the non-combustible thin plate burns and falls off in the event of a fire, it is possible to prevent the non-combustible thin plate from falling off together with the combustible material.

In the fireproof structure of the fourth invention, the non-combustible thin plates (for example, non-combustible thin plates 40A and 40B described later) are doubly attached to the outer surface of the support member, and the double non-combustible thin plates are connected members (for example, for example. It is characterized in that it is supported by the support member via a connecting member 42) described later.

Here, the connecting member is, for example, rod-shaped, and examples thereof include nails and screws.
According to the present invention, since the non-combustible thin plate is provided twice, the air layer is also doubled, and even if the combustible material burns around the structural member, the radiant heat from the combustible material is transmitted to the structural member. It can be suppressed more.

According to the present invention, it is possible to provide a fireproof structure capable of more reliably protecting structural members such as columns and beams from heat during a fire.

It is a plan sectional view of the fireproof structure which concerns on 1st Embodiment of this invention. It is a perspective view of the fireproof structure. It is a plan sectional view which shows the situation at the time of a fire of the said fireproof structure. It is a schematic side view which shows the structure of the Example and the comparative example of this invention. It is a figure which shows the relationship between the temperature of the object surface and the heat flux flowing into the object surface about the said Example and a comparative example. It is a plan sectional view of the fireproof structure which concerns on 2nd Embodiment of this invention. It is a plan sectional view of the fireproof structure which concerns on 3rd Embodiment of this invention. It is a plan sectional view which shows the situation at the time of a fire of the said fireproof structure. It is a vertical sectional view of the fireproof structure which concerns on the 1st modification of this invention. It is a perspective view of the fireproof structure which concerns on the 2nd modification of this invention. It is an exploded perspective view of the fireproof structure which concerns on the 3rd modification of this invention.

The present invention is a fireproof structure in which a structural material is covered with a non-combustible thin plate. In the first embodiment, a refractory coating material is provided on the outer peripheral surface of the pillar, and a non-combustible thin plate is arranged on the outside of the refractory coating material with an air layer interposed therebetween (FIGS. 1 to 3). The second embodiment is different from the first embodiment in that a plurality of pins are provided on the outer surface of the non-combustible thin plate, and the finishing material is locked to the pins (FIG. 6). The third embodiment is different from the first and second embodiments in that the non-combustible thin plates are double-arranged (FIGS. 7 and 8). The modified example differs from the first to third embodiments in that the target of the fireproof structure is a beam instead of a pillar (FIG. 9).
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the following embodiments, the same components will be designated by the same reference numerals, and the description thereof will be omitted or simplified.
[First Embodiment]
FIG. 1 is a plan sectional view of a fireproof structure 1 of a pillar 10 according to the first embodiment of the present invention. FIG. 2 is a perspective view of the fireproof structure 1.

The pillar 10 is a structural member constituting the building and is a square steel pipe. A fireproof coating material 20, an air layer 30, a non-combustible thin plate 40, and a finishing material 50 are laminated and arranged in this order on the outer peripheral surface of the pillar 10.
That is, the outer peripheral surface of the pillar 10 is covered with the non-combustible thin plate 40. Further, a fireproof coating material 20 is provided on the outer surface of the pillar 10. The air layer 30 is provided between the refractory coating material 20 and the non-combustible thin plate 40.
The fireproof coating material 20 is sprayed rock wool. The non-combustible thin plate 40 is a rectangular tubular steel plate. The finishing material 50 is a combustible material attached to the surface of the non-combustible thin plate 40, and is, for example, wood.
Support members 11 which are lip channel steels extending along the axial direction of the pillar 10 are provided at the four corners of the pillar 10 in the air layer 30, and the non-combustible thin plate 40 is attached to the outer surface of the support member 11. Has been done.

In the fire-resistant structure 1 as described above, in the event of a fire, the finishing material 50 burns around the pillar 10 as shown in FIG. 3, but the heat of the fire is transferred to the fire-resistant coating material 20 by the non-combustible thin plate 40 and the air layer 30. Is suppressed.

Below, the radiation reduction effect of the steel plate (non-combustible thin plate) is calculated.
Specifically, as an embodiment of the present invention, it is assumed that a steel plate is provided away from the surface of an object (pillar and fireproof coating material) as shown in FIG. 4A. In this case, the inside of the steel plate is the air layer, and the outside of the steel plate is the fire space. Further, as a comparative example, as shown in FIG. 4B, it is assumed that the steel plate is not provided on the outside of the surface of the object (pillar and refractory coating material). In this case, the outside of the object surface becomes the fire space. For these examples and comparative examples, the heat flux flowing into the object surface is calculated.

The calculation conditions are set as follows. The view factor of each surface of the steel plate and the surface of the object is 1. The convection heat transfer coefficient is 0.023 kW / m ² / K. The emissivity is 0 for the air layer and 1 for the others. Then, the heat balance of the steel plate is as shown in the following equation (1).

In equation (1), T is temperature [K], V is volume [m ³ ], ρ is density [kg / m ³ ], c is specific heat [kJ / kg], and σ is Stefan-Boltzmann constant (5.67). × ^10-11 kW / m ² / K ⁴ ), ε is the emissivity, F is the view factor, A is the area [m ² ], and h is the convection heat transfer rate [kW / m ² / K]. Further, as the subscripts of each symbol, p is a steel plate, f is a fire space, s is an object surface, and a is an air layer.
In the formula (1), the left side is the change in the amount of heat stored in the steel plate in a unit time, and the right side is the heat flow rate to the steel plate in a unit time. Specifically, the first term on the right side is the net radiant heat flow from the fire space to the steel plate, and the second term on the right side is the net convection heat flow from the fire space to the steel plate. The term is the net radiant heat flow from the surface of the object to the steel plate, and the fourth term on the right side is the net convective heat flow from the air layer to the steel plate.
Since the steel plate is thin and the heat capacity V _p ρ _p c _p is small, if the left side of equation (1) is regarded as 0 and arranged, the relationship between the steel plate and other temperatures is as shown in equation (2) below. become.

Then, when the steel plate is provided, the net heat flux flowing into the object surface is as shown in equation (3), and when the steel plate is not provided, the net heat flux flowing into the object surface is as shown in equation (4). )become that way.

For example, the temperature of the fire space is 945 ° C. The temperature of the air layer is also set to 945 ° C. in consideration of the possibility of the hot air flow in the fire space flowing in. When the temperature of the object surface was 100 ° C., 200 ° C., 300 ° C., 400 ° C., and 500 ° C., the temperature of the steel plate was obtained according to the formula (2), and the result and the formula (3) and the formula (4) were followed. The heat flux flowing into the surface of the object was calculated. As a result, the relationship between the temperature of the object surface and the heat flux flowing into the object surface is as shown in FIG. 5. From FIG. 5, when the steel plate is provided, compared with the case where the steel plate is not provided, the relationship is as shown in FIG. It can be seen that the heat flux flowing into the surface of the object is about 60%.

According to this embodiment, there are the following effects.
(1) Since the outer peripheral surface of the pillar 10 constituting the building is covered with the air layer 30 and the non-combustible thin plate 40, even if the finishing material 50 burns around the pillar 10 in the event of a fire, the non-combustible thin plate 40 and the air layer 30 As a result, the heat of the fire is suppressed from being transmitted to the fireproof coating material 20 (radiation reduction effect), and the pillar 10 can be more reliably protected from the heat at the time of the fire.
(2) Since the fireproof coating material 20 is provided on the outer surface of the pillar 10, the pillar 10 can be more reliably protected from the heat of a fire.

(3) Since the non-combustible thin plate 40 is attached to the outer surface of the support member 11 arranged at the four corners of the pillar 10, the non-combustible thin plate 40 is secured while securing the air layer 30 between the refractory coating material 20 and the non-combustible thin plate 40. Can be supported by. Therefore, even if the finishing material 50 provided on the outside of the non-combustible thin plate 40 burns and falls off in the event of a fire, it is possible to prevent the non-combustible thin plate 40 from falling off together with the finishing material 50.

[Second Embodiment]
FIG. 6 is a cross-sectional view of the fireproof structure 1A of the pillar 10 according to the second embodiment of the present invention.
The present embodiment is different from the first embodiment in that a plurality of pins 41 are provided on the outer surface of the non-combustible thin plate 40, and the finishing material 50 is locked to these pins 41.
According to this embodiment, in addition to the above-mentioned effects (1) to (3), there are the following effects.
(4) Since the finishing material 50 is locked to the pin 41 provided on the outer surface of the non-combustible thin plate 40, it is possible to prevent the finishing material 50 from falling off.

[Third Embodiment]
FIG. 7 is a cross-sectional view of the fireproof structure 1B of the pillar 10 according to the third embodiment of the present invention.
The present embodiment is different from the first embodiment in that the non-combustible thin plates 40A and 40B are doubly attached to the outer surface of the support member 11.
That is, the inner non-combustible thin plate 40A and the outer non-combustible thin plate 40B are supported by the support member 11 via the connecting member 42. That is, a rod-shaped connecting member 42 extending outward is attached to the support member 11, and the noncombustible thin plates 40A and 40B are supported on the connecting member 42 at predetermined intervals. Further, the finishing material 50 is locked to a portion of the connecting member 42 protruding from the non-combustible thin plate 40B.
Further, in the present embodiment, the finishing material 50 is provided not only on the outer surface of the outer non-combustible thin plate 40B but also between the non-combustible thin plate 40A and the non-combustible thin plate 40B.

In the fireproof structure 1B as described above, as shown in FIG. 8, not only the finishing material 50 on the outer surface of the outer non-combustible thin plate 40B but also the finishing material 50 between the non-combustible thin plates 40A and 40B is burned in the event of a fire. Then, an air layer 30A is also formed between the non-combustible thin plate 40A and the non-combustible thin plate 40B. Therefore, the non-combustible thin plates 40A and 40B and the air layers 30 and 30A suppress the heat of the fire from being transmitted to the refractory coating material 20.
According to this embodiment, in addition to the above-mentioned effects (1) to (4), there are the following effects.
(5) Since the non-combustible thin plates 40A and 40B are provided in double, the air layers 30 and 30A are also doubled, and the heat of the fire can be further suppressed from being transmitted to the pillar 10.

The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.
For example, in each of the above-described embodiments, a steel plate is used as the non-combustible thin plate 40, but the present invention is not limited to this, and mortar plate, calcium silicate plate, stainless steel plate, ceramic fiber cloth, galvalume steel plate (registered trademark), and galvanized steel plate can be used. You may use it.
Further, in each of the above-described embodiments, sprayed rock wool is used as the fireproof coating material 20, but the present invention is not limited to this, and a foamable fireproof paint, a mortar plate, or a wrapping type rock wool felt may be used.
Further, in each of the above-described embodiments, the present invention is applied to the column 10, but the present invention is not limited to this, and as shown in FIG. 9, the present invention is applied to the beam 60 which is an H-shaped steel to obtain a fireproof structure 1C. May be good. The beam 60 has a structure that supports the floor slab 61.

Further, as shown in FIG. 10, in each embodiment, the rock wool felt 21 may be provided inside the upper ends of the non-combustible thin plates 40, 40A, and 40B. Similarly, rock wool felt may be provided inside the lower end of the non-combustible thin plate 40. Further, as shown in FIG. 10, rock wool felt 21 may be provided inside the joint portions 43 between the non-combustible thin plates 40. With such a configuration, the degree of sealing of the air layer 30 is increased, and the hot airflow in the fire space is less likely to enter the air layer 30, so that the fire resistance performance can be further improved.

Further, as shown in FIG. 11, in each embodiment, a folded-back portion 44 formed by bending outward is provided at a side end portion of the non-combustible thin plates 40, 40A, 40B, and a screw 45 is attached to the folded-back portion 44. By attaching, adjacent non-combustible thin plates 40, 40A, 40B may be joined to each other. By providing such a folded-back portion 44, the non-combustible thin plates 40, 40A, and 40B can be made to stand on their own even after the finishing material 50 is burnt down in the event of a fire. Further, in this case, since the non-combustible thin plates 40, 40A, and 40B are self-supporting, the support member 11 may be omitted.
Further, in each of the above-described embodiments, the fireproof coating material 20 is provided on the outer surface of the pillar 10, but the present invention is not limited to this, and the fireproof coating material may not be provided.

1, 1A, 1B, 1C ... Fireproof structure 10 ... Pillar (structural member) 11 ... Support member 20 ... Fireproof coating material 21 ... Rock wool felt 30, 30A ... Air layer 40, 40A, 40B ... Non-combustible thin plate 41 ... Pin 42 ... Connecting member 43 ... Joint part 44 ... Folded part 45 ... Screw 50 ... Finishing material 60 ... Beam (structural member)
61 ... Floor slab

Claims (4)

Structural members that make up the building and
A non-combustible thin plate that covers the structural member is provided.
A fireproof structure characterized in that an air layer is provided between the structural member and the non-combustible thin plate. A fireproof coating material is provided on the outer surface of the structural member.
The fireproof structure according to claim 1, wherein the air layer is provided between the fireproof coating material and the noncombustible thin plate. The air layer is provided with a support member extending along the axial direction of the structural member.
The fireproof structure according to claim 1 or 2, wherein the non-combustible thin plate is attached to the outer surface of the support member. The non-combustible thin plate is doubly attached to the outer surface of the support member.
The fireproof structure according to claim 3, wherein the double non-combustible thin plate is supported by the support member via a connecting member.

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