JP2017128844A - Fireproof steel beam - Google Patents

Abstract

The present invention provides a refractory steel beam that is easy to construct and has high fire resistance, and whose lower surface of a lower flange is covered with a thermally expandable sheet.
A steel beam composed of two flanges facing each other in the horizontal direction and a single web connecting the two flanges,
Among the two flanges, a thermally expandable refractory material that continuously covers at least a part of the lower surface and side surfaces and at least the upper surface of the lower flange located below,
A heat-dissipating member located on the thermally expandable refractory material along both upper end portions of the lower flange,
At least a sprayed refractory material continuously covering the web side surface and the heat-dissipating member upper surface;
Having refractory steel beam.
[Selection] Figure 1

Description

  The present invention relates to a refractory steel beam for a building.

  Steel beams of fire-resistant buildings were heated by fire according to Building Standards Act Article 2-7, Article 2-9-2, Building Standards Act Enforcement Ordinance 107, Article 108-3 In some cases, it is required not to cause deformation, melting, destruction or other damage that hinders structural strength. In order to satisfy this requirement, it is widely practiced to coat steel beams with sprayed refractory materials. For example, when rock wool is used as a fireproof material for spraying, it is necessary to cover steel beams with thicknesses of 25, 40, and 60 mm, respectively, according to the fireproof time of 1, 2, and 3 hours. When the lower surface of a steel beam is covered with a fire-resistant material with a thickness of 60 mm, the floor height increases accordingly, so in a multi-level building, the height of the entire building increases and the construction cost increases. There is a problem.

  In order to reduce the coating thickness on the lower surface of the steel beam, there is a method in which a thermally expandable refractory material is applied from the lower surface of the lower flange of the steel beam to a part of the upper surface, and sprayed refractory material is sprayed on the other surface of the steel beam. Proposed. Here, the sprayed refractory material is made of a material that is difficult to pass heat. When the sprayed refractory material is sprayed onto the thermally expandable refractory material, the sprayed refractory material on the thermally expandable refractory material makes it difficult for heat to reach the thermally expandable refractory material. Therefore, there arises a problem that the coating thickness is reduced, and the start of expansion of the thermally expandable refractory material is delayed. Therefore, it is necessary to form the sprayed refractory material so as not to overlap the thermally expandable refractory material. Further, when the end of the thermally expandable refractory material is covered with the sprayed refractory material, the portion of the thermally expandable refractory material adjacent to the sprayed refractory material is pressed against the adjacent sprayed refractory material, thereby inhibiting the expansion. .

  Patent Document 1 proposes a fireproof covering structure in which a thermally expandable fireproof sheet is attached to at least an outer surface of a lower flange of two flanges of a steel beam having an H-shaped cross section. FIG. 7 shows FIG. In the invention described in Patent Document 1, the thermally expandable refractory sheet has the same width as the lower flange (FIG. 7: FIG. 4 of Patent Document 1) or overhangs (see FIGS. 5 and 6 of Patent Document 1). It is done.

In the fireproof coating structure in which the thermally expandable fireproof sheet proposed in Patent Document 1 has the same width as the lower flange, an auxiliary plate is required below the lower flange when spraying the nonflammable material (Patent Document). 1 (see FIG. 3). The auxiliary plate must be supported by some kind of support member, and a process such as installation / removal of the support member and the auxiliary plate is necessary, and the construction is complicated. Further, the heat-expandable fireproof sheet expands in the thickness direction and hardly expands in the width direction. Therefore, in the fireproof coating structure in which the thermally expandable fireproof sheet has the same width as the lower flange, there is a problem that even if the thermally expandable fireproof sheet expands, the coating thickness is insufficient at the side end portion of the lower flange.
Further, in the fireproof covering structure in which the thermally expansible fireproof sheet proposed in Patent Document 1 projects from the lower flange, in the paragraphs 0054 and 0059 of Patent Document 1, the thermally expandable fireproof sheet that projects outwardly is supplemented. It is described that an auxiliary plate is unnecessary at the time of construction in order to fulfill the function of the plate. However, the thermally expandable refractory sheet has flexibility, and the sprayed noncombustible material immediately after spraying contains heavy water. There is a problem that the thickness of the incombustible material is changed by bending, and further, the incombustible material before curing flows down. Therefore, it is necessary to provide an auxiliary plate for actual construction.

  In Patent Document 2, there is a foaming refractory material provided continuously from the lower surface of the flange connected to the lower end of the web to the upper surface of the flange around the both ends, and in order not to overlap the foaming refractory material. A steel beam fireproof covering structure provided with a foamable refractory material has been proposed. FIG. 8 shows FIG. 5 of Patent Document 2. In FIG.

  Patent Document 2 does not describe the construction method in detail, but high dimensional accuracy is required to construct the non-foaming refractory material so as not to overlap the foaming refractory material by spraying. For such construction, it is necessary to use a formwork, but when installing and dismantling the formwork, the non-foaming refractory material and the foaming refractory material are damaged. There is a problem of lowering. Moreover, the process of installation / disassembly of a formwork is required, and construction is complicated.

  In addition, although not disclosed at the time of filing this application, the applicant, in Patent Document 3, provided the first and second upright members on the upper surface of the lower flange, and the lower side from the upper end of the side surface of the first upright member. Cover the entire surface from the side flange to the upper end of the side of the second rising member with a thermally expandable fireproof sheet, and cover the part sandwiched between the web and the side of the rising member with the sprayed fireproof material. is suggesting. FIG. 9 shows FIG. 1 of Patent Document 3.

JP 2013-227752 A JP 2013-199809 A Japanese Patent Application No. 2015-097968

  It is an object of the present invention to provide a refractory steel beam that is easy to construct and has high fire resistance, and whose lower flange is covered with a thermally expandable sheet.

1. A steel beam composed of two flanges facing each other in the horizontal direction and one web connecting the two flanges;
Among the two flanges, a thermally expandable refractory material that continuously covers at least a part of the lower surface and side surfaces and at least the upper surface of the lower flange located below,
A heat-dissipating member located on the thermally expandable refractory material along both upper end portions of the lower flange,
At least a sprayed refractory material continuously covering the web side surface and the heat-dissipating member upper surface;
A refractory steel beam characterized by comprising:
2. The heat-expandable fireproof material is a heat-expandable fireproof sheet. The refractory steel beam described in 1.
3. The heat-dissipating member is made of a foamed resin. Or 2. The refractory steel beam described in 1.
4). 1. The cross section of the heat-dissipating member is a right triangle, and the hypotenuse of the right triangle is located on the web side. ~ 3. The refractory steel beam according to any one of the above.
5. 1. The thickness of the heat-dissipating member is 0.7 times or less the thickness of the refractory layer of the heat-expandable refractory material located under the heat-dissipating member. ~ 4. The refractory steel beam according to any one of the above.
6). In the upper surface of the lower flange, the width of the thermally expandable refractory material is wider than the width of the heat-dissipating member. ~ 5. The refractory steel beam according to any one of the above.

  In the refractory steel beam of the present invention, the lower surface of the lower flange is covered with a thermally expandable refractory material, and the overall height of the refractory steel beam including the refractory coating can be reduced. be able to. In a building structure having a plurality of floors such as a high-rise building, one floor may be increased by reducing the floor height.

  In the refractory steel beam of the present invention, the thermally expandable refractory material is a type for not forming the spray refractory material on the thermally expandable refractory material because the spray refractory material is applied in a state protected by the heat-dissipating member. No frame is required. Further, since the sprayed refractory material is formed on the rigid lower flange, no contact plate is required. For this reason, the thermal expansion refractory material and the sprayed refractory material are not damaged by the contact associated with the installation / disassembly of the formwork or the backing plate, and the fire resistance performance is not deteriorated. The refractory steel beam of the present invention does not require a formwork or the like when spraying the blast refractory material, and the construction work is simple, and the construction period can be shortened.

The heat-dissipating member made of foamed resin is lightweight and can be transported manually from the material storage to the work site. In addition, when working on higher floors, a necessary amount of heat-dissipating member can be transported by an elevator, and there is no need to lift by a crane. The heat-dissipating member made of foamed resin is flexible, and even if it collides with a worker or a wall during transportation, the worker is not injured or the wall is not damaged. Construction of refractory steel beams is an operation at a high place, but a heat-dissipating member made of foamed resin may cause injury to the worker or damage to the floor surface even if the heat-dissipating member is dropped from a high place. There is no.
Further, the foamed resin has a small amount of ash remaining after being lost by heating. This ash does not hinder the heat input to the thermally expandable refractory material, and does not prevent the thermally expanded refractory layer from filling the gap formed by the disappearance of the foamed resin.
By disposing the heat-dissipating member having a right-angled triangular cross section so that the hypotenuse of the right-angled triangle is located on the web side, the gap generated when the heat-dissipating member disappears becomes narrower toward the back. By being pressed against the sprayed refractory material, a gap generated in a portion where the expansion of the thermally expandable refractory material is inhibited is narrow, so that even if the expansion is inhibited, the gap can be filled with the refractory material.

  In the refractory steel beam of the present invention, the heat-dissipating member disappears in the early stage of the fire and a gap is formed. When the thickness of the heat-dissipating member is 0.7 times or less the thickness of the heat-resistant layer of the heat-expandable refractory material, the heat-dissipating member is It is possible to reliably fill the gaps that have disappeared. As a result, the fireproof layer produced by thermal expansion of the sprayed fireproof material and the thermally expandable fireproof material is in close contact, and the steel beam can be covered without any breaks.

  When a thermally expandable refractory sheet is used as the thermally expandable refractory material, it is easy to manage the thickness of the refractory layer generated by thermal expansion. Moreover, it can prevent that a thermally expansible fireproof sheet falls from a lower flange by sticking a thermally expansible fireproof sheet so that at least one part of the upper surface of a lower flange may be covered. Furthermore, by making the width of the heat-expandable fireproof sheet wider than the width of the heat-dissipating member on the upper surface of the lower flange, the end portion of the heat-expandable fireproof sheet can be fixed with a sprayed fireproof material. By fixing the edge part of a thermally expansible fireproof sheet with a spray hardening material, it can prevent that a thermally expansible fireproof sheet falls from a lower flange.

Sectional drawing of the 1st embodiment of the refractory steel beam of the present invention. The figure which shows the behavior at the time of the fire of the 1st embodiment of the refractory steel beam of the present invention. The figure which shows the behavior at the time of the fire of the 1st embodiment of the refractory steel beam of the present invention. Sectional drawing of the 2nd embodiment of the refractory steel beam of the present invention. The figure which shows the behavior at the time of the fire of the 2nd embodiment of the refractory steel beam of this invention. The figure which shows the behavior at the time of the fire of the 2nd embodiment of the refractory steel beam of this invention. The figure which shows the fireproof coating structure of patent document 1. FIG. The figure which shows the fireproof coating structure of patent document 2. FIG. The figure which shows the fireproof coating structure of patent document 3. As shown in FIG.

The present invention is a refractory steel beam in which a heat-expandable refractory material, a heat-dissipating member, and a sprayed refractory material are laminated in this order on both end portions on the upper surface of the lower flange.
In the refractory steel beam of the present invention, the heat-dissipating member disappears in the early stage of the fire, and a gap is generated between the thermally expandable refractory material and the sprayed refractory material. When heat is further applied, the heat-expandable refractory material thermally expands, covers the lower and side surfaces of the lower flange with a fire-resistant layer having a required thickness, and the gap formed by the disappearance of the heat-dissipating member. Fill.
In the fire-resistant steel beam of the present invention, the fire-resistant layer generated by thermal expansion of the sprayed fire-resistant material and the heat-expandable fire-resistant material covers the steel beam in the event of a fire, and the fire-resistant layer is a gap formed by the disappearance of the heat-dissipating member. By filling with, desired fire resistance performance can be exhibited.

“The refractory steel beam of the first embodiment”
A cross-sectional view of a first embodiment of the refractory steel beam of the present invention is shown in FIG.
The refractory steel beam 1 according to the first embodiment includes a steel beam 2, a thermally expandable refractory material 3, a heat dissipation member 4, and a sprayed refractory material 5.

  The steel beam 2 includes an upper flange 21 and a lower flange 22 that face each other in the horizontal direction, and a web 23 that connects the upper flange and the lower flange. The steel beam 2 supports the horizontal section 6 such as a floor of a building structure, and the horizontal section 6 is provided on the upper flange 21. The steel beam 2 can be used as appropriate.

  The thermally expandable refractory material 3 continuously covers the lower surface and side surfaces of the lower flange 22 and at least a part of the upper surface. The heat-expandable refractory material 3 is in the form of a film or a sheet at the normal time, and is thermally expanded to form a refractory layer and protect the steel beam when exposed to a predetermined temperature or more during a fire or the like. Any one or both of fire resistant paint, thermally expandable fire resistant sheet can be used. Examples of fire-resistant paints include those manufactured by Nippon Insulation Co., Ltd., trade name “Tyca Bale”, manufactured by SK Kaken Co., Ltd., trade name “SK Taika Coat”, manufactured by Nippon Paint Co., Ltd., trade name “Taikarit”, and Kikusui Chemical Co. The product name “Westa” manufactured by the company, the product name “Nullfire” (Nullifier), etc., manufactured by Nullfire Inc., UK can be used. As the heat-expandable fireproof sheet, for example, Sekisui Chemical Co., Ltd., trade name “Fiblo”, SK Kaken Co., Ltd., trade name “SK Tyca Sheet”, etc. can be used. A heat-expandable fire-resistant sheet is preferable because it is easy to manage the thickness of the fire-resistant layer that expands during a fire.

  When a heat-expandable fireproof sheet is used as the heat-expandable fireproof material 3, the heat-expandable fireproof sheet covers at least a part of the upper surface of the lower flange 22 so that the heat-expandable fireproof sheet is detached from the lower flange. Can be prevented from falling. The heat-expandable fireproof sheet only needs to cover a part of the upper surface of the lower flange 22, and does not need to cover the entire upper surface. A thermally expansible fireproof sheet can also cover the said location continuously by bonding a plurality of sheets together without a gap. Moreover, the heat-expandable refractory sheet can be laminated and bonded to increase the thickness of the refractory layer generated by thermal expansion.

  The heat-dissipating member 4 is located on the heat-expandable refractory material 3 along both end portions on the upper surface of the lower flange 22. The heat-dissipating member 4 disappears by burning, melting, or the like with the heat at the time of the fire before the heat-expandable refractory material 3 starts to expand. As the heat-dissipating member 4, for example, non-halogen, non-aromatic flammable resin such as polyethylene, polypropylene, poly (meth) acrylic resin, polystyrene, cardboard, cardboard, or the like can be used. Among these, a foamed resin, cardboard, and cardboard obtained by foaming an easily combustible resin are preferable because they easily disappear by heat, are light and easy to handle, and can be easily cut to a required length. Furthermore, the foamed resin can be more suitably used because the amount of ash after disappearance is small.

The thickness of the heat-dissipating member 4 is the thickness of the fire-resistant layer produced by the expansion of the heat-expandable refractory material 3 located under the heat-dissipating member 4 (= film thickness of the heat-expandable refractory material × expansion coefficient). It is as follows. Here, the term “expansion coefficient” means the thickness of the thermally expandable refractory material after irradiation with 50 kW / m ² of radiant heat for 20 minutes / the thickness of the thermally expandable refractory material when not expanded. In addition, as the thermally expandable refractory material 3, one having an expansion coefficient of about 10 to 30 times is widespread. The thickness of the heat-dissipating member 4 is preferably 0.7 times or less the thickness of the refractory layer (= film thickness of the heat-expandable refractory material × expansion coefficient). When the thickness of the heat-dissipating member 4 is 0.7 times or less of the thickness of the refractory layer, the heat-dissipating member 4 disappears in the event of a fire-resistant layer formed by thermal expansion of the heat-expandable refractory material 3. Can be reliably filled.

The sprayed refractory material 5 continuously covers the side surface of the web 23 and the upper surface of the heat-dissipating member 4. As the sprayed refractory material 5, a popular product such as rock wool, ceramic, or gypsum can be used as appropriate. Moreover, the thickness of the sprayed refractory material 5 is determined according to predetermined fireproof performance.
Here, on the upper surface of the lower flange, when the width of the heat-expandable refractory material is wider than the width of the heat-dissipating member, the end portion of the heat-expandable refractory material is covered and fixed with the sprayed refractory material. By fixing the end portion of the heat-expandable refractory material with the sprayed refractory material, it is possible to prevent the heat-expandable refractory material from falling from the lower flange over a long period of time from construction.

"Construction method"
The refractory steel beam 1 which is the first embodiment can be constructed by the following method.
The thermally expandable refractory material 3 is pasted so as to continuously cover the lower surface and side surfaces of the lower flange 22 and at least a part of the upper surface. Next, the heat-dissipating member 4 is fixed on the heat-expandable refractory material 3 with an adhesive, a double-sided tape or the like along both ends of the upper surface of the lower flange 22. A curing sheet made of polyethylene or the like is attached to the side surfaces of the heat-expandable refractory material 3 and the heat-dissipating member 4 and, if necessary, the lower surface of the heat-expandable refractory material 3. After spraying the sprayed refractory material 5 so as to continuously cover the side surface of the web 23 and the upper surface of the heat-dissipating member 4 with a predetermined thickness, the sprayed refractory material 5 is shaped with a trowel or the like as necessary. Remove the curing sheet.

  The construction method of the refractory steel beam 1 does not require a formwork or an auxiliary plate when the sprayed refractory material 5 is sprayed. Since the sprayed refractory material 5 does not have fluidity like liquid and has adhesion, it does not flow down from the upper surface of the lower flange. Moreover, the space | interval of the thermally expansible refractory material 3 and the spraying refractory material 5 in a both-sides upper part of a lower flange can be managed only by arrange | positioning the heat-dissipating member 4 of predetermined thickness, and a spraying refractory material When spraying 5, high dimensional accuracy is not required. Therefore, the refractory steel beam 1 of the present invention is easy to construct, and there is no risk of damaging the thermally expandable refractory material 3 or the sprayed refractory material 5 at the time of installation or removal of a formwork or the like. It can prevent a decline in sex.

"Behavior during fire"
The behavior at the time of fire of the refractory steel beam 1 which is the first embodiment will be described.
When heat is applied to the refractory steel beam 1 due to a fire, the heat-dissipating member 4 first disappears. The refractory steel beam 1 is not in contact with the heat-expandable refractory material 3 and the sprayed refractory material 5 at both ends of the upper surface of the lower flange 22, and when the heat-dissipating member 4 disappears, A gap V is formed between the sprayed refractory material 5 (FIG. 2).
When the fire further progresses, the heat-sensitive compound contained in the thermally expandable refractory material 3 starts to react, and the thermally expandable refractory material 3 thermally expands to form the refractory layer 31. Since the thermally expandable refractory material 3 mainly thermally expands in the thickness direction, the refractory layer 31 covers the lower surface and side surfaces of the lower flange 22 with a necessary thickness. Further, in the gap V, the thermally expandable refractory material 3 is heated and thermally expanded without being obstructed by the sprayed refractory material 5, and reliably fills the gap V as designed (FIG. 3).
The steel beam 2 is covered with the sprayed refractory material 5 and the refractory layer 31, and the gap V where the heat-dissipating member 4 disappears is filled with the refractory layer 31, thereby exhibiting desired fire resistance performance.

"The refractory steel beam of the second embodiment"
FIG. 4 shows an enlarged cross-sectional view of the lower flange portion of the second embodiment of the refractory steel beam of the present invention. In FIG. 4, the same members as those in FIG.
The refractory steel beam 11 according to the second embodiment includes a heat-dissipating member 41 having a right triangle shape in cross section, and the oblique side of the heat-dissipating member 41 is located on the web 23 side. The size of the angle (α) formed by the base of the right triangle and the hypotenuse is preferably 30 ° or more and 60 ° or less. By making the height (h) of the right triangle equal to the thickness according to the design performance of the sprayed refractory material 5, the sprayed refractory material 5 is simply sprayed to the same height (h) as the heat-dissipating member 41. It can be made thick, and the thickness management of the sprayed refractory material is easy.

"Behavior during fire"
The behavior at the time of fire of the refractory steel beam 11 which is a 2nd embodiment is demonstrated.
As with the refractory steel beam 1 of the first embodiment, when heat is applied by a fire, the heat-dissipating member 41 first disappears and a gap V is generated (FIG. 5).
As the fire further progresses, the thermally expandable refractory material 3 expands and the refractory layer 31 fills the gap V (FIG. 6). In the refractory steel beam 11 according to the second embodiment, the cross section of the gap V is a right triangle, and the height decreases as it is pulled back. Since the gap V in the portion of the thermally expandable refractory material 3 adjacent to the sprayed refractory material 5 is small, even if the expansion of the end of the thermally expandable refractory material 3 is pressed against the sprayed refractory material 5, the gap V is formed in the refractory layer 31. Can be filled more reliably.

DESCRIPTION OF SYMBOLS 1 Refractory steel beam 2 Steel beam 21 Upper flange 22 Lower flange 23 Web 3 Thermal expansion refractory material 31 Refractory layer 4 Heat dissipation member 5 Spray refractory material 6 Horizontal division

V gap

11 Refractory steel beam 41 Heat dissipation member

Claims (6)

A steel beam composed of two flanges facing each other in the horizontal direction and one web connecting the two flanges;
Among the two flanges, a thermally expandable refractory material that continuously covers at least a part of the lower surface and side surfaces and at least the upper surface of the lower flange located below,
A heat-dissipating member located on the thermally expandable refractory material along both upper end portions of the lower flange,
At least a sprayed refractory material continuously covering the web side surface and the heat-dissipating member upper surface;
A refractory steel beam characterized by comprising:   The refractory steel beam according to claim 1, wherein the thermally expandable refractory material is a thermally expandable refractory sheet.   The refractory steel beam according to claim 1, wherein the heat-dissipating member is made of a foamed resin.   The refractory steel beam according to any one of claims 1 to 3, wherein the cross section of the heat-dissipating member is a right triangle, and the hypotenuse of the right triangle is located on the web side.   The thickness of the heat-dissipating member is 0.7 times or less the thickness of the fire-resistant layer of the thermally expandable refractory material located under the heat-dissipating member. The refractory steel beam according to any one of the above. The refractory steel beam according to any one of claims 1 to 5, wherein a width of the thermally expandable refractory material is wider than a width of the heat dissipation member on the upper surface of the lower flange.

Images