JP7216580B2 - Fireproof reinforcement structure - Google Patents

Description

The present invention relates to a fireproof reinforcing structure.

Conventionally, as a technique in this field, a fireproof heat insulating structure described in Patent Document 1 below is known. This fire-resistant structure is, for example, in structures such as buildings and civil engineering structures, in which a non-combustible heat insulating material is attached to a base material to which fire resistance is to be imparted, and an expandable fire-resistant material is further laminated thereon. .

Patent No. 4106503

The fire-resistant structure as described above can be used for a fire-resistant reinforcement structure that reinforces fire resistance by further installing an expandable fire-resistant material on the existing non-combustible heat insulating material. However, when the fire-resistant reinforcing structure is applied to a steel frame made of H steel, depending on the conditions, when the foamable refractory material is heated during a fire, excessive foaming and carbonization occur, especially in the portion covering the lower flange of H steel. The fireproof material falls off due to gravity, the fireproof performance of the portion covering the lower flange is lowered, and eventually the fireproofness is not sufficiently reinforced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fire-resistant reinforcement structure that sufficiently reinforces the fire resistance of steel frames to which an existing fire-resistant coating layer is applied.

The fire-resistant reinforcing structure of the present invention is a fire-resistant reinforcing structure for reinforcing the fire resistance of a steel frame having an existing fire-resistant coating layer applied to the surface, and the existing fire-resistant reinforcing structure covers at least the lower surface of the lower flange of H steel constituting the steel frame. A first sheet made of a foamable refractory material that is installed outside the fireproof coating layer of and has a foaming layer that contains a foaming agent and foams when heated and a backing layer that backs the foaming layer, and at least the lower surface of the lower flange of H steel a second sheet provided outside the first sheet so as to cover the second sheet, the second sheet having a support layer that supports the first sheet in a state in which the foam layer is foamed by heating ; contains no blowing agent. The first sheet and the second sheet may be fastened to the steel frame with pins welded to the steel frame.

According to this configuration, even if the foam layer of the first sheet foams during a fire, the first sheet is supported by the support layer of the second sheet existing outside the first sheet. The possibility of falling off is reduced, and the deterioration of fire resistance performance is suppressed.

As a specific configuration, the support layer may be made of the same material as the backing layer of the first sheet. Also, the second sheet may be made of the same foamed refractory material as the first sheet. Also, the support layer may be made of a glass mesh.

ADVANTAGE OF THE INVENTION According to this invention, the fire-resistant reinforcement structure which fully reinforces the fire resistance of the steel frame to which the existing fire-resistant coating layer was given can be provided.

It is a cross-sectional view of the fireproof reinforcing structure of the embodiment. (a) is sectional drawing which shows an example of the fireproof reinforcement structure of FIG. 1, (b) is sectional drawing which shows another example. (a) is a front view showing a specimen used in the experiment, and (b) is a cross-sectional view taken along IIIb-IIIb. 4(a) and 51(b), respectively, are graphs showing temperature changes of respective portions of H steel for the fireproof reinforcement structure 1 and for the fireproof reinforcement structure 51. FIG.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the fireproof reinforcement structure which concerns on this invention is described in detail, referring drawings. In each drawing, the same or equivalent components are denoted by the same reference numerals, and overlapping descriptions are omitted. In each drawing, the features of the components may be exaggerated and schematically depicted, and the dimensional ratio of each component in the drawings does not necessarily match the actual product.

FIG. 1 is a cross-sectional view of a steel frame 3 to which a fireproof reinforcing structure 1 of this embodiment is applied. The steel frame 3 is a beam of the building and is made of H steel. The structure in which the fireproof coating layer 5 is applied to the surface of the steel frame 3 is the existing fireproof structure before reinforcement. The fireproof reinforcement structure 1 of this embodiment is constructed so that the fireproofness of the existing fireproof structure of such a steel frame 3 is further reinforced. In the fireproof reinforcing structure 1 , a fireproof reinforcing layer 7 is provided outside the fireproof coating layer 5 . The fireproof reinforcing layer 7 includes a first sheet S1 placed outside the fireproof coating layer 5 and a second sheet S2 placed outside the first sheet S1.

The steel frame 3 is made of H400x200x8x13 mm H steel, for example, and has an upper flange 11 , a web 13 and a lower flange 15 . The fireproof coating layer 5 is applied to the entire surface of the steel frame 3 except for the upper surface of the upper flange 11, and the upper surface of the upper flange 11 is in close contact with the floor 17 (for example, ALC floor, RC floor, etc.) above the steel frame 3. are doing.

The material of the existing fireproof coating layer 5 is not particularly limited as long as it is a noncombustible material, a quasi-noncombustible material, or a material having performance equivalent thereto as defined in the Building Standards Act. For example, inorganic molded plates such as calcium silicate plates, perlite cement plates, gypsum boards, rock wool plates, and glass wool heat insulating plates, or sheets, mats, and blankets made from rock wool, ceramic wool, glass wool, slag wool, etc. etc. Among these heat insulating materials, a heat insulating material having a thermal conductivity of 0.5 kcal/m·hr·°C or less is particularly preferable.

The first sheet S<b>1 is installed immediately outside the fireproof coating layer 5 so as to cover the lower surface of the lower flange 15 of the steel frame 3 . The second sheet S<b>2 is installed so as to cover the entire steel frame 3 except for the upper surface of the upper flange 11 . The second sheet S2 is placed immediately outside the first sheet S1 in the portion covering the lower surface of the lower flange 15, and in the portion covering the lower surface of the upper flange 11, the web 13, and the upper surface of the lower flange 15, It is installed immediately outside the refractory coating layer 5 . That is, the first sheet S1 and the second sheet S2 are doubly overlapped in the portion of the fireproof reinforcing layer 7 that covers the lower surface of the lower flange 15 of the steel frame 3 .

As shown in the enlarged cross section of FIG. 2(a), the first sheet S1 includes two layers: a foam layer 19 containing a foaming agent and foamed by heating, and a backing layer 21 backing the foam layer 19. It consists of a sheet-like foamed refractory material 23 containing. A commercially available foamed refractory material may be employed as the foamed refractory material 23 of this embodiment. The first sheet S1 is placed on the fire-resistant coating layer 5 with the backing layer 21 facing inward (the fire-resistant coating layer 5 side). The second sheet S2 is made of the same foamed refractory material 23 as the first sheet S1. That is, the second sheet S2 is a foamed fireproof material composed of two layers, the foam layer 19 and the backing layer 21, and the backing layer 21 side of the second sheet S2 is inside (fireproof coating layer 5 side). It is placed on the first sheet S1 facing The first sheet S<b>1 and the second sheet S<b>2 are fastened and fixed at appropriate points by pins (not shown) welded to the steel frame 3 , for example.

The foam layer 19 of the foamable refractory material 23 is heated in the event of a fire and foams when it reaches a predetermined temperature, forming a carbonized heat insulating layer that expands, for example, to a thickness of about 30 times. Due to the heat insulating property of this carbonized heat insulating layer, the foamed layer 19 after foaming has a heat insulating function. The foam layer 19 is formed by coating the backing layer 21 with a known fire-resistant foam paint. The foam layer 19 contains a binder, a flame retardant, a foaming agent, a carbonizing agent, a filler, and the like. These components exhibit functions such as foaming of the foamed layer 19, formation of a carbonized layer, and generation of non-flammable gas by their mutual combined actions when a fire occurs.

Among them, the foaming agent contained in the foaming layer 19 mainly has the effect of generating a nonflammable gas in the event of a fire, foaming the carbonizing binder and the carbonizing agent, and forming a carbonized heat insulating layer containing pores. It demonstrates. Examples of foaming agents include melamine and its derivatives, dicyandiamide and its derivatives, azodicarbonamide, urea and thiourea. These foaming agents can be used alone or in combination of two or more.

In addition, the flame retardant exhibits at least one effect such as a dehydration cooling effect, a nonflammable gas generating effect, a binder carbonization promoting effect, etc. in the event of a fire, and prevents or suppresses the burning of the binder. The carbonizing agent exhibits the effect of forming a thick carbonized heat insulating layer with excellent heat insulating properties by dehydrating and carbonizing itself together with the carbonization of the binder due to fire. Fillers improve the strength of the carbonized thermal insulation layer and increase fire resistance. As these binders, flame retardants, foaming agents, carbonizing agents, and fillers, those used in known foamable refractory materials can be used.

The backing layer 21 backs the foam layer 19, maintains the shape of the coating film of the foam layer 19, and secures mechanical strength, thereby facilitating handling of the sheet-like foamed refractory material 23. . The backing layer 21 does not contain a foaming agent. Compared with the foam layer 19, the backing layer 21 is less likely to be carbonized, deformed, or degraded in mechanical strength by heat during a fire. As an example, a glass mesh is adopted as the material of such backing layer 21 .

The thickness of the expandable refractory material 23 is appropriately set according to the required performance, and is, for example, 1.5 to 3 mm. Among them, the thickness of the foam layer 19 is, for example, 1.3 mm, and the thickness of the backing layer 21 is, for example, 0.2 mm. For example, in the one-hour fire-resistant specification, the thickness of the expandable fire-resistant material 23 is desirably 1.5 mm.

Next, the effects of the fireproof reinforcement structure 1 will be described. As shown in FIGS. 1 and 2 , in the fireproof reinforcing structure 1 , a fireproof reinforcing layer 7 is provided further outside the existing fireproof coating layer 5 to enhance fire resistance. It is conceivable that the foam layer 19 included in the fire-resistant reinforcing layer 7 may be excessively foamed due to the heat applied to the fire-resistant reinforcing layer 7 at the time of fire, and the foamed layer 19 may drop off after foaming. In particular, the foamed layer 19 after foaming may fall off due to gravity in the portion of the fireproof reinforcing layer 7 that covers the lower surface of the lower flange 15 . Since this type of foam layer 19 exhibits a heat insulating effect by foaming in the event of a fire, if the foam layer 19 falls off after foaming, the fire resistance of the foam layer 19 is lost.

On the other hand, in the fireproof reinforcing layer 7 in the fireproof reinforcing structure 1, the second sheet S2 made of the foamable fireproof material 23 is further provided on the outer layer of the first sheet S1 made of the foamable fireproof material 23 on the lower surface of the lower flange 15. become. Even if the foamed layer 19 of the second sheet S2 falls off, the backing layer 21 of the second sheet S2 is unlikely to be carbonized, deformed, or degraded in mechanical strength. remains attached to the steel frame 3. Then, even when the foam layer 19 of the first sheet S1 is heated and foamed, the backing layer 21 of the second sheet S2 remaining on the outer layer functions as a support layer 27 that supports the first sheet S1.

Therefore, the foam layer 19 of the first sheet S1 is supported by the backing layer 21 of the second sheet S2 as the support layer 27, and is prevented from coming off the steel frame 3. The foam layer 19 of the first sheet S<b>1 remains on the steel frame 3 in a foamed state, and exhibits a heat insulating function for the steel frame 3 and the fireproof coating layer 5 . In this way, in the event of a fire, at least the foam layer 19 of the first sheet S1 of the fireproof reinforcing layer 7 maintains the heat insulation function with the outer layer of the fireproof coating layer 5, so that the existing steel frame 3 and fireproof By adding the fireproof reinforcement layer 7 to the coating layer 5, the fireproofness is sufficiently enhanced.

It should be noted that if the foamable refractory material 23 is directly installed on the steel frame 3 without sandwiching the fireproof coating layer 5, part of the heat in the event of a fire escapes from the foamable refractory material 23 to the steel frame 3. , the heat of the foamable refractory material 23 does not rise too much, and the foaming layer 19 is prevented from being excessively foamed. That is, when the existing fireproof coating layer 5 is applied to the steel frame 3 and fireproof reinforcement is performed by installing the expandable fireproof material 23 on the fireproof coating layer 5, the need for the fireproof reinforcement structure 1 is particularly high.

Next, experiments conducted by the inventors will be described with reference to FIGS. 3 and 4. FIG. FIG. 3(a) is a front view showing the H-steel used in the experiment, and the longitudinal direction of the H-steel corresponds to the horizontal direction in the drawing. FIG. 1 shows the I-I cross section in FIG. 3(a), and FIG. 3(b) shows the IIIb-IIIb cross section in FIG. 3(a). As shown in Fig. 3(a), an H steel of H400x200x8x13mm with a length of 5000mm is prepared as a steel frame 3, and starting from the central position M in the longitudinal direction of this H steel, a range of length 1500mm is shown in Fig. 1 on the right side. A refractory reinforced structure 1 as shown was formed. For comparison, a fireproof reinforcement structure 51 having a cross section shown in FIG.

As shown in FIG. 3(b), the fireproof reinforcement structure 51 is constructed by covering an existing fireproof structure in which the fireproof coating layer 5 is applied to the surface of the steel frame 3 with a sheet of foamed fireproof material 23. be. Here, the foamed refractory material 23 is not installed along the surface of the H steel, but is formed in a U-shaped cross section to cover the steel frame 3 and the refractory coating layer 5 . The foamed refractory material 23 forms the immediate outer layer of the refractory coating layer 5 on the lower surface of the lower flange 15 of the H-beam 15 and is in contact with the refractory coating layer 5 . In addition, between the upper flange 11 and the lower flange 15, the foamable refractory material 23 is directly bridged between the edge portion of the upper flange 11 and the edge portion of the lower flange 15, and the foamable refractory material 23 and the web 13 there is a cavity 29 .

At the boundary between the fireproof reinforcement structure 1 and the fireproof reinforcement structure 51, the following heat insulation portion was formed. As shown in FIG. 3( a ), the cavity 29 of the fireproof reinforcement structure 51 is filled with a heat insulating material in the range from the central position M to the left with a length of 100 mm, and similarly from the central position M to the right with a length of 100 mm. A recess surrounded by the web 13 of the fireproof reinforcement structure 1 and the upper and lower flanges 11 and 15 was filled with a heat insulating material. Furthermore, as the outer layer, a heat insulating material with a thickness of 50 mm was attached with a fire-resistant adhesive to the area of 200 mm in length where the heat insulating material exists.

In the fire-resistant reinforcing structures 1 and 51, the fire-resistant coating layer 5 is sprayed rock wool (25 mm thick) of 1-hour fire-resistant specification sprayed on the surface of the steel frame 3. Moreover, as the foamable fireproof material 23 used for the fireproof reinforcing structures 1 and 51, a commercially available foamable fireproof material was used. The foamed fireproof material 23 has a thickness of 1 mm, of which the foam layer 19 has a thickness of 0.8 mm and the backing layer 21 has a thickness of 0.2 mm. The backing layer 21 is made of glass mesh. In general commercially available foamed refractories, a sheet with a thickness of 1.5 mm corresponds to one-hour fire resistance specification, so the fire resistance of foamed fire-resistant material 23 used here is one hour fire resistance specification. is less than

In a cross section 500 mm away from the central position M on the right side, each temperature measurement point was set on the H steel surface of the fireproof reinforcement structure 1, and a thermocouple 31 was installed respectively. The temperature measurement points are the lower surface of the upper flange (back side), the lower surface of the upper flange (front side), the center of the web (back side), the center of the web (front side), the top surface of the lower flange (back side), and the top surface of the lower flange (front side). , the lower surface of the lower flange (back side), and the lower surface of the lower flange (front side). The temperature measurement points on the lower surface of the upper flange (back side) and the lower surface of the upper flange (front side) are located 30 mm away from the edge of the upper flange 11. The temperature measurement points on the lower surface of the lower flange (back side) and the lower surface of the lower flange (front side) are located 10 mm away from the edge of the lower flange 15 . The temperature measurement points at the center of the web (back side) and the center of the web (front side) are located at the center of the web 13 in the vertical direction. Similarly, 8 temperature measurement points were set in a section 1000 mm away from the central position M to the right, so that a total of 16 temperature measurement points were set in the fireproof reinforcing structure 1 . Similarly, in the fireproof reinforcing structure 51, a total of 16 temperature measurement points were set at positions symmetrical to the fireproof reinforcing structure 1, and the thermocouples 31 were installed.

The above specimens were heated according to ISO834 for 2 hours, after which the heating was stopped and allowed to cool. FIG. 4A shows a graph of temporal changes in temperature at each temperature measurement point of the fireproof reinforcement structure 1, and FIG. 4B shows a graph of temporal change in temperature at each temperature measurement point of the fireproof reinforcement structure 51. 4A and 4B are roughly divided into a group of curves T11 showing temperature changes at four points on the upper flange 11, a group of curves T13 showing temperature changes at four points on the web 13, and eight points on the lower flange 15. There are three curve groups such as a curve group T15 showing temperature changes of . In each of the curve groups T11, T13, and T15, the curves included in the curve groups are similar to each other and need not be distinguished in detail, so individual consideration of each curve is omitted here.

As shown in FIG. 4(b), the temperature of the H steel in the refractory reinforcement structure 51 is 500°C maximum for the lower flange (peak of curve group T15), 460°C maximum for the web (peak of curve group T13), The flange reached a maximum of 320°C (peak of curve group T11). Therefore, it was found that the fireproof reinforcing structure 51 also achieves the goal of keeping the temperature of the H steel below 550°C. On the other hand, as shown in Fig. 4(a), the temperature of the H steel in the refractory reinforcement structure 1 is a maximum of 450°C for the lower flange (the peak of curve group T15) and a maximum of 460°C for the web (the peak of curve group T13). peak), and the upper flange reached a maximum of 320°C (peak of curve group T11). In the fireproof reinforcing structure 1 , the temperature of the lower flange in particular was suppressed compared to the fireproof reinforcing structure 51 . Therefore, according to the fire-resistant reinforcement structure 1, the temperature of the H-steel can be suppressed to 550° C. or less, and furthermore, the temperature of the H-steel can be suppressed even compared to the fire-resistant reinforcement structure 51.

From the above, it was confirmed that the fireproof reinforcing structure 1 has advantageous effects compared to the fireproof reinforcing structure 51 .

The present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art, including the embodiment described above. Moreover, it is also possible to configure a modified example using the technical matters described in the above-described embodiments. You may use it, combining the structure of each embodiment suitably.

In the embodiment, the first sheet S1 and the second sheet S2 are made of the same fire-resistant foam 23, but the first sheet S1 and the second sheet S2 may be made of different types of fire-resistant foam. That is, the foam layer 19 of the first sheet S1 and the foam layer 19 of the second sheet S2 may be different in material and thickness. The layers 21 may differ in material and thickness from each other.

Further, as described above, it is the backing layer 21 of the second sheet S2 that functions as the support layer 27 that supports the first sheet S1 after foaming. Therefore, even if the foam layer 19 of the second sheet S2 falls off at an early stage, or even if the foam layer 19 of the second sheet S2 does not exist from the beginning, it is considered that the above effects can be achieved. Therefore, the second sheet S2 may have only one layer of the backing layer 21 as the support layer 27, as shown in FIG. 2(b). That is, the fireproof reinforcing layer 7 comprises a first sheet S1 consisting of two layers, the foam layer 19 and the backing layer 21, and a second sheet S2 consisting only of the backing layer 21 as the support layer 27. good too. In this case, the support layer 27 of the second sheet S2 should be the same as the backing layer 21 of the foamable fireproof material 23, as long as it can support the first sheet S1 in which the foam layer 19 is foamed. is not essential and may be a layer made of another material.

However, according to the structure of FIG. 2(a), the foam layer 19 is included not only in the first sheet S1 but also in the second sheet S2, thereby obtaining higher fire resistance than the structure of FIG. 2(b). . Further, in the structure of FIG. 2(a), if the first sheet S1 and the second sheet S2 are made of the same foamed fireproof material 23, the sheet material can be shared, and construction efficiency is good.

Further, in the embodiment, the first sheet S1 is arranged so as to cover only the lower surface of the lower flange 15 of the steel frame 3, but the first sheet S1 may cover the entire steel frame 3 except for the upper surface of the upper flange 11. . Also, the first sheet S1 may be arranged so as to cover only the upper and lower surfaces of the lower flange 15 of the steel frame 3 . Among the foam layers 19 of the first sheet S1, the foam layer 19 existing on the lower surface of the lower flange 15 is particularly prone to fall off due to the influence of gravity. may be placed in Further, in the lower flange 15, between the first sheet S1 and the second sheet S2, one or a plurality of foamed fireproof materials 23 may be sandwiched and present.

DESCRIPTION OF SYMBOLS 1...Fire-resistant reinforcement structure, 3...Steel frame, 15...Lower flange, 19...Foam layer, 21...Backing layer, 27...Supporting layer, S1...First sheet, S2...Second sheet.

Claims (4)

A fireproof reinforcement structure that reinforces the fireproofness of a steel frame on which an existing fireproof coating layer is applied,
A foam layer that is installed outside the existing fireproof coating layer so as to cover at least the lower surface of the lower flange of the H steel constituting the steel frame, contains a foaming agent and is foamed by heating, and a backing layer that backs the foam layer. a first sheet made of an intumescent refractory material having
A second sheet installed outside the first sheet so as to cover at least the lower surface of the lower flange of the H steel,
The second sheet is
a support layer that supports the first sheet in which the foam layer is foamed by heating ;
A fire-resistant reinforcing structure , wherein the support layer does not contain a foaming agent . The fireproof reinforcing structure according to claim 1, wherein the first sheet and the second sheet are fixed to the steel frame with pins welded to the steel frame. 3. The fireproof reinforcing structure according to claim 1 or 2 , wherein the support layer is made of the same material as the backing layer of the first sheet. The second sheet is
Made of the same foamed fireproof material as the first sheet ,
comprising the backing layer and the foam layer,
The fireproof reinforcing structure according to any one of claims 1 to 3 , wherein the backing layer of the second sheet functions as the support layer .

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