JP2010059703A - Steel beam fireproof structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel beam fireproof structure reducing a lowering of the ceiling height due to the thickness of fireproof coating and excelling in workability without complicated management or the like of spray thickness. <P>SOLUTION: The steel beam fireproof structure has a steel beam comprising an upper end, a lower end and a web located between the upper end and lower end and positioning the upper end on the deck plate side and the lower end on the ceiling side respectively between the deck plate and the ceiling of a building, and a first fireproof coating that covers the beam bottom face of the lower end. The first fireproof coating has a fireproof blanket formed in plate or strip shape; a noncombustible metallic foil that covers at least one surface of the fireproof blanket; and an adhesive part formed on the first fireproof coating surface located on the side facing the surface of the fireproof blanket 1. The first fireproof coating is mounted to the steel beam by the adhesive part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fireproof structure for a steel beam of a building.

When steel beams used as building beams are directly exposed to high heat such as fire, the strength of the beams cannot be denied. Therefore, steel beams (for example, steel beams with an H-shaped cross section (hereinafter sometimes referred to as “H-shaped steel beams”)) are fire-resistant so that the required strength can be maintained even when exposed to high heat such as fire. It is stipulated by laws and regulations to cover with covering.
As such a conventional steel beam fireproof structure, for example, as shown in FIG. 4, there is one in which rock wool is sprayed on the H-shaped steel beam 10 to a thickness of 60 mm to form a fireproof coating 20 (the figure shows the H-shaped steel beam). It shows an example in which rock wool is sprayed on the surfaces of the upper flange 11, the web 12 and the lower flange 13 of the steel beam 10. The upper surface (upper end surface) 11a of the upper flange 11 supports the deck plate 30. And no rock wool is sprayed.) In such a steel beam fireproof structure, when the rock wool spraying thickness T is, for example, 60 mm, the fire resistance of 3 hours defined by laws and regulations can be realized. In place of such rock wool spraying, there is also a steel beam fireproof structure that covers the H-shaped steel beam 10 with a plate-shaped or felt-shaped fireproof coating (for example, Patent Documents 1 to 3). Such a steel beam fireproof structure is said to be excellent in workability (constructability) at a construction site because it is unnecessary to spray rock wool.

However, in any steel beam refractory structure, the thickness T of the refractory coating 20 is the same (for example, thickness 60 mm) in any part. Therefore, the ceiling 40 positioned on the lower surface (beam bottom surface 13a) side of the lower flange 13 is at least the thickness T (for example, 60 mm) of the fireproof coating 20 from the lower surface (beam bottom surface) of the lower flange 13 of the H-shaped steel beam 10. Or it will be positioned further away. That is, the ceiling height is lowered by the thickness of the fireproof coating 20 on the beam bottom surface 13a. As a steel beam refractory structure in consideration of these problems, the rock wool spraying thickness T on the H-shaped steel beam 10 is made thin at the beam bottom surface 13a, while it is made thicker at the other parts to make the H-shaped steel beam 10 as a whole. There is a steel beam fireproof structure that secures the fire resistance (for example, Patent Document 4).
JP 2005-179903 A JP 2005-179904 A JP 2005-179905 A JP 2002-30309 A

  However, the thickness of spraying rock wool or the like to the H-shaped steel beam 10 is reduced at the beam bottom surface 13a (the thickness of spraying is set according to the part of the H-shaped steel beam 10). It cannot be denied that the spraying work, the management (or inspection) of the spraying thickness, and the like are complicated. Therefore, the present invention aims to realize a steel beam fireproof structure that reduces the drop in ceiling height due to the thickness of the fireproof coating, is excellent in workability, and does not involve complicated management of the spraying thickness. .

In the steel beam fireproof structure according to the present invention (Claim 1), the steel beam including the upper end portion, the lower end portion, and the web positioned between the upper end portion and the lower end portion is provided between the deck plate and the ceiling of the building. In the meantime, the upper end portion is positioned on the deck plate side and the lower end portion is positioned on the ceiling side, and the beam bottom surface of the lower end portion is covered with the first fireproof coating.
Here, the first fire-resistant coating is formed on a side of the fire-resistant blanket that faces the surface of the fire-resistant blanket, a fire-resistant blanket that is formed in a plate shape or a strip shape, a non-combustible metal foil that covers at least one surface of the fire-resistant blanket, and It has the adhesion part formed in the 1st fireproof covering surface located, and is attached to the steel beam by the adhesion part. Such a first refractory coating is superior to the conventional refractory coating by spraying or felt because the refractory blanket is shielded from fire flames and the like by the incombustible metal foil covering the surface of one of the refractory blankets. It is possible to achieve a fire-resistant coating that is thinner than conventional fire-resistant coatings.

Therefore, in the steel beam fireproof structure, the height of the ceiling can be increased by reducing the distance between the bottom surface of the lower flange of the steel beam (beam bottom surface) and the ceiling without complicated management of the blowing thickness, etc. It is possible to achieve the fire resistance specified in. In addition, the fire-resistant blanket can be easily attached to the steel beam at the bonded portion, and the workability at the construction site can be improved.
In the steel beam fireproof structure according to the second aspect, a steel beam having an H-shaped cross section in which a lower flange is formed at the lower end and an upper flange is formed at the upper end is used.

  In the steel beam refractory structure according to claim 3, the steel beam is covered with a refractory coating, leaving at least an upper end surface in contact with the deck plate, and the first refractory of the region covered with the refractory coating. The remaining area of the area covered with the refractory coating is covered with a refractory coating different from the first refractory coating. For example, as in the steel beam fireproof structure according to the fourth aspect, a second fireproof coating can be formed by spraying a fireproof coating different from the first fireproof coating.

  As in the steel beam refractory structure according to claim 5, in the boundary region between the first refractory coating and a refractory coating different from the first refractory coating (for example, the second refractory coating), If a positioning member for positioning the fireproof coating is used, the first fireproof coating attached to the lower flange can be more reliably attached and, for example, the second fireproof coating can be sprayed. As well as improving workability.

The steel beam refractory structure according to claim 6 covers the bottom surface of the lower flange with the first refractory coating together with the surface (surface on the web side) facing the bottom surface of the beam. In such a steel beam fireproof structure, the workability is improved because the lower flange is covered only with the first fireproof coating.
The steel beam refractory structure according to claim 7 has an adhesive portion formed of an adhesive member. For example, if the adhesive portion is formed of a double-sided adhesive tape with adhesive or the like applied to both sides, the first fireproof coating can be easily attached to the steel beam and the workability is improved.

  As described above, according to the present invention, since the fire resistance equivalent to that of the conventional fireproof coating can be realized by using the thin first fireproof coating, the ceiling height is reduced by the fireproof coating. Can be reduced. If the reduction in the ceiling height can be reduced in this way, the interior can be expanded, the added value of the building can be increased, and the space between the deck plate and the ceiling on each floor can be reduced. The construction cost can be reduced. In addition, according to the present invention, the first fire-resistant coating can be easily attached to the steel beam at the bonding portion, and a steel beam fire-resistant structure without complicated management of the spray thickness can be realized.

  In addition, if a region other than the region covered with the first fireproof coating is a conventional fireproof coating by spraying, the fireproof coating on the web having through holes or the like that complicate the shape of the fireproof coating. The workability of formation can be improved.

  Hereinafter, a steel beam fireproof structure according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the component which has a function similar to the conventional steel beam fireproof structure, and the description is abbreviate | omitted.

  FIG. 1 shows a schematic sectional structure and a planar schematic structure of a first fireproof coating, FIG. 2 shows a schematic sectional structure of a steel beam fireproof structure according to the present invention, and FIG. 3 shows a steel frame. The attachment of the first refractory coating to the beam will be described.

(First fireproof coating)
A first refractory coating 20 shown in FIG. 1 is obtained by covering a peripheral surface of a refractory blanket 21 formed in a plate shape or a strip shape with a nonflammable metal foil 22 (FIG. 1A is nonflammable). The cross-sectional schematic structure of the 1st fireproof coating 20 of the state which covered the peripheral surface with the metal foil 22 is shown. The refractory blanket 21 is formed into a plate shape or a belt shape having a thickness of about 30 mm by overlapping a number of thin ceramic fibers formed in a thin belt shape, and has flexibility. The non-flammable metal foil 22 is an aluminum foil-clad glass cloth that is hard to break and has a gloss, prevents the fire-resistant blanket 21 from being directly exposed to hot air such as a fire, and the temperature of the fire-resistant blanket 21 due to heat conduction. The rise can be mitigated, and the temperature rise of the refractory blanket 21 can be mitigated by reflecting the heat rays radiated by the flame or the like. Therefore, the first fire resistant coating 20 is superior in fire resistance to the conventional fire resistant coating by spraying or felt.

  The first refractory coating 20 is formed in a strip shape having a width W of about 400 mm and a thickness T1 of 30 mm, for example, rolled up, and is easy to transport and store. It can be cut and used according to the length. As shown in FIG. 1A, the first refractory coating 20 has a peripheral surface composed of one surface 20a, the other surface 20b, and two side end surfaces 20c. As shown, a central adhesive portion 23a and two side adhesive portions 23b and 23c are provided in parallel on the surface of one surface 20a. The center adhesive portion 23a is provided at the center portion in the width direction of the first fireproof coating 20 with a width of about 200 mm, and is provided in the center distribution portion. The side adhesive surface 23b is provided on the side end face 20c side of the central adhesive portion 23a. And 23c are provided with a width of about 100 mm. The distance between the central adhesive portion 23a and the side adhesive portions 23b and 23c is a little over 10 mm. The center adhesive portion 23a and the side adhesive portions 23b and 23c are each formed of a double-sided adhesive tape in which an adhesive is applied to both surfaces of the tape.

(Steel beam)
The H-shaped steel beam 10 is attached by connecting between steel columns (not shown), and as shown in FIG. 2, the upper flange 11 supports the deck plate 30 (the upper surface 11a of the upper flange 11). The deck plate 30 is positioned on the top). The width of the upper flange 11 and the lower flange 13 (in the horizontal direction in FIG. 2) is 200 mm, the height of the H-shaped steel beam 10 (in the vertical direction in FIG. 2) is 400 mm, and the H-shaped steel beam 10 is The upper flange 11, the web 12 and the lower flange 13 have a thickness of 8 mm. In the H-shaped steel beam 10, the lower flange 13 is covered with a first refractory coating 20, and then the web 12 and the upper flange 11 are covered with a second refractory coating 25. These refractory coatings are formed as follows.

(Coating of steel beams with fireproof coating)
The first refractory coating 20 is cut so as to match the distance between the steel columns to which the H-shaped steel beam 10 is connected. Next, the seal covering the adhesive surface (of the double-sided adhesive tape) of the central adhesive portion 23a of the first fireproof coating 20 is peeled off, and the widthwise center of the first fireproof coating 20 is the web as shown in FIG. 12, the adhesive surface of the central adhesive portion 23 a is adhered to the beam bottom surface 13 a of the lower flange 13. The width of the central adhesive portion 23a is set to about 200 mm in accordance with the width of 200 mm of the lower flange 13. However, in order to prevent the adhesive surface of the central adhesive portion 23a from protruding from the beam bottom surface 13a of the lower flange 13, It is better that it is slightly narrower than the width of the flange 13.

  Next, after peeling off the seal covering the adhesive surfaces of the side adhesive portions 23b and 23c of the first fireproof coating 20, the web side surface 13b of the lower flange 13 (the upper surface of the lower flange 13 in FIG. 3). Is covered with the first fireproof coating 20 and adhered with the side adhesive portions 23b and 23c (two-dot chain arrows A and B in FIG. 3). In the state where the lower flange 13 is thus covered with the first fireproof coating 20, the other surface 20b of the first fireproof coating 20 becomes the surface, and the two side end surfaces 20c of the first fireproof coating 20 The web 12 is substantially in contact with the web 12 in the vicinity of the boundary portion between the web 12 and the lower flange 13.

In addition, the area | region (area | region where the double-sided adhesive tape is not adhere | attached) between the center adhesion part 23a and the side part adhesion part 23b contacts the side end surface 13c of the lower flange 13. As shown in FIG. The same applies to the region between the central adhesive portion 23a and the side adhesive portion 23c (the central adhesive portion 23a, the side adhesive portion 23b, and the side adhesive portion 23c may be integrated).
Next, as shown in FIG. 2, the first refractory coating 20 is positioned on the web-side surface 13 b of the lower flange 13 on both sides of the web 12 using the two positioning members 24. The positioning member 24 is obtained by applying an adhesive to one surface of the nonwoven fabric, and is adhered to both surfaces of the web 12 and the other surface 20 b of the first refractory coating 20.

  Next, as shown in FIG. 2, the second refractory coating 25 is formed by spraying rock wool. The second fire-resistant coating 25 covers the web side surface 11b of the upper flange 11 (the surface facing the upper surface 11a of the upper flange 11), the deck plate in the vicinity thereof, and both surfaces of the web 12, and the lower flange 13 side. Then, the surfaces of the two positioning members 24 are also covered. Even if a slight gap is formed between the two side end surfaces 20c of the first fireproof coating 20 and the web 12, such a gap is closed by the two positioning members 24, and further the second fireproof. Since it is covered with the conductive coating 25, the fire resistance is not lowered.

  The first fireproof coating 20 may be one in which only one surface 21 a of the fireproof blanket 21 is covered with a nonflammable metal foil 22. This is because the first refractory coating 20 is adhered to the lower flange 13 so that the non-combustible metal foil 22 becomes the surface, so that the refractory blanket 21 is not directly exposed to hot air such as a fire, and heat The rise in temperature due to conduction is alleviated, and the radiating heat rays such as flame are reflected by the non-combustible metal foil 22 so that the rise in temperature is mitigated. In addition, even if the two side end surfaces 20c of the first fireproof coating 20 are not covered with the nonflammable metal foil 22, they are closed with the positioning member 24 and further covered with the second fireproof coating 25. Does not cause a drop in fire resistance.

  In such a fireproof structure, the distance between the beam bottom surface 13a of the lower flange of the H-shaped steel beam 10 and the ceiling 40 can be set to 30 mm, which is the thickness of the first fireproof coating 20, and thus has a thickness of 60 mm. The ceiling height can be 30 mm higher than the conventional fireproof coating. If the ceiling height is the same as the conventional one, the height of the building can be lowered by 30 mm per floor. For example, in the case of a 50-story building, the height of the building is 1.5 m (100 floors). In the case of (3), it can be lowered by 3 m) and the construction cost can be reduced.

  In the fireproof structure, since the beam bottom surface 13a of the lower flange 13 of the H-shaped steel beam 10 only needs to be covered with the first fireproof coating 20, the web side surface 13b of the lower flange 13 is made to be the second. It may be covered with a fireproof coating 25. In this case, the first fireproof coating 20 is preferably one in which the side end face 20c is covered with the nonflammable metal foil 22 in order to improve the fire resistance in the vicinity of the side end face 20c.

In the embodiment described above, the two positioning members 24 may be omitted. In this case, even if a slight gap is formed between the two side end surfaces 20c of the first fireproof coating 20 and the web 12, the second fireproof coating 25 is sprayed into the gap, or It is covered with the fireproof coating 25 of 2, and a fire resistance fall is not caused.
Alternatively, all of the refractory coatings may be the first refractory coating 20. That is, the first refractory coating 20 may be adhered to both surfaces of the web 12 of the H-shaped steel beam 10 and the upper surface 11 a of the upper flange 11. In addition, when providing the through-hole which penetrates the sleeve for piping, wiring, etc. in the web 12 of the H-shaped steel beam 10, the web 12 forms the 2nd fireproof coating 25 by spraying rock wool. This is preferable because the workability is improved.

For example, when a fire resistance time shorter than the above-described fire resistance time is allowed, the thickness of the first fireproof coating 20 can be reduced to, for example, 12.5 mm to 15 mm. Even in this case, the first refractory coating 20 is still thinner than the conventional refractory coating.
As described above, the present invention is not limited to each embodiment, and can be implemented by being appropriately modified without departing from the spirit of the present invention.

It is a figure which shows the cross-sectional schematic structure of the fireproof coating used for the steel beam fireproof structure concerning this invention, and a plane schematic structure. It is a figure which shows the cross-sectional schematic structure of the steel beam fireproof structure concerning this invention. It is a figure for demonstrating attachment etc. of a 1st fireproof coating in the steel beam fireproof structure shown in FIG. It is a figure which shows the cross-sectional schematic structure of a steel beam fireproof structure.

Explanation of symbols

10 H-shaped steel beam 11 Upper flange 11a Upper surface of upper flange (upper end surface)
12 Web 13 Lower flange 13a Beam bottom surface 13b Web side surface of lower flange 20 First fireproof coating 21 Blanket 21 1 surface of blanket 23a Central adhesive part (adhesive part)
23b Side bonding part (bonding part)
23c Side bonding part (bonding part)
24 Positioning member 25 Second fireproof coating 30 Deck plate 40 Ceiling

Claims (7)

An upper end, a lower end, and a web positioned between the upper end and the lower end; between the deck plate and the ceiling of the building, the upper end on the deck plate side, and the lower end In the steel beam fireproof structure having a steel beam positioned on the ceiling side and a first fireproof coating covering the bottom surface of the beam at the lower end,
The first refractory coating is
A fire-resistant blanket formed into a plate or belt,
An incombustible metal foil covering at least one surface of the refractory blanket;
An adhesive portion formed on the first refractory coating surface on the side opposite to the one surface of the refractory blanket;
A steel beam refractory structure, wherein the steel beam is attached to the steel beam at the bonding portion.   The steel beam refractory structure according to claim 1, wherein the steel beam is a steel beam having an H-shaped cross section in which a lower flange is formed at the lower end and an upper flange is formed at the upper end. The steel beam is covered with a refractory coating, leaving at least the upper flange of the upper flange in contact with the deck plate,
Of the region covered with the refractory coating, the remaining region of the region covered with the first refractory coating is covered with a refractory coating different from the first refractory coating. The steel beam fireproof structure according to claim 2.   The steel beam refractory structure according to claim 3, wherein the refractory coating different from the first refractory coating is a second refractory coating formed by spraying.   4. A positioning member for positioning the first fireproof coating in a boundary region between the first fireproof coating and a fireproof coating different from the first fireproof coating. 4. The steel beam fireproof structure according to 4.   The steel beam according to any one of claims 2 to 5, wherein the first fireproof coating covers a beam bottom surface of the lower flange and a web side surface of the lower flange facing the beam bottom surface. Fireproof structure.   The steel beam fireproof structure according to any one of claims 1 to 5, wherein the adhesive portion is formed of an adhesive member.

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