JP2844005B2 - Fireproof structure with fireproof coating on steel tubular concrete structural members - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fire-resistant structure in a structural member such as a column of a steel pipe concrete structure.

(Prior Art) In the case of a steel pipe structure, there have been reported several examples of a water-cooled steel pipe type construction method in which the inside of a steel pipe column is filled with water to perform no refractory coating.

In this water-cooled steel pipe method, as shown in Fig. 16, a water storage tank (a) is installed at the upper part of the layer, and the upper part of each steel pipe column (b) and the tank (a) are connected by an upper pipe (c). Then, the lower part of each steel pipe column (b) is connected by a lower pipe (d) so that even if the column is exposed to the flame and the water temperature of that part rises, the cooling water comes to the part exposed to the flame by convection. In this case, the column temperature is prevented from excessively rising, and when the water evaporates and decreases, the water is supplied from the upper water storage tank.

Therefore, when the above-mentioned construction method is employed, such capital investment is required.However, since the cost for this is generally less expensive than the case of providing a fire-resistant coating, the water-cooled steel pipe construction method is considered to have a large utility value. Although it is conceivable, there are only a few examples in the United States, such as the US Steel Building in the United States and the Steel Federation Building in Dutzseldorf, West Germany, and there are no examples in Japan.

(Problems to be Solved by the Invention) The reasons are as follows.

(I) Since a large water pressure acts on the lower pillar, the lower pillar needs to be thicker to withstand the water pressure, which increases the cost.

In the case of the US steel building, for example, the columns are divided into 16 layers according to the water pressure limit, and a water storage tank is installed at the top of each layer to connect the top and bottom of each column.

(Ii) Seismic design is required in Japan. In this case, the seismic force is generally evaluated as the product of the weight of the floor multiplied by a certain coefficient.If a water-cooled steel pipe method of filling the inside of steel pipe columns with water is adopted, this Weight must also be taken into account when converting seismic force, which can lead to cost increases.

Therefore, in the case of the water-cooled steel pipe method, the proof strength of the column member is greater than the case where the fireproof coating is performed without water in the column,
There is a need to increase the stiffness, which leads to cost increases and consequently is not economical.

On the other hand, in recent years, in order to ensure the strength and rigidity of
Steel pipe concrete members in which concrete is filled in steel pipes have been frequently used. In the case of steel pipe concrete members, since the heat capacity of concrete is large, it has been clarified that the surface temperature of the steel pipe does not increase even if the thickness of the refractory coating is reduced as compared with ordinary steel members. It is not generally accepted before it is lost.

The present invention has been proposed in view of such circumstances,
The aim is to provide a fire-resistant structure with a fire-resistant coating on steel pipe concrete structural members that is economical and does not lower the strength and rigidity without raising the temperature of the steel pipe above a certain temperature even in the event of a fire. On the point.

(Means for Solving the Problems) In order to achieve the above object, a fire-resistant structure with a fire-resistant coating in a steel pipe concrete structural member according to the present invention is provided with a void portion in a filled concrete portion in a steel pipe in the steel pipe concrete structural member. In addition, the space is filled with a heat absorbing material.

The invention according to claim 2 is characterized in that the gap filled with the heat absorbing material provided in the filled concrete filling portion in the steel pipe is constituted by an iron pipe provided close to the steel pipe, and between the steel pipe and the steel pipe. In which a metal material having a high thermal conductivity is interposed.

According to a third aspect of the present invention, water is used as a heat absorbing material to be filled in the gap, and a convection water channel is provided in which the gap is connected to a water storage tank and upper and lower portions of the gap by piping.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the air gap is provided near the inner surface of the steel pipe and at the central portion thereof, and a convection water channel is provided at a lower layer portion.

(Operation) In the present invention, since the fire-resistant coating material does not exist in the steel pipe concrete structural member, the temperature of the surface of the steel pipe that is directly subjected to the flame increases in the event of a fire. Since the heat absorbing material filled in the tube absorbs heat, the temperature rise on the surface of the steel pipe is delayed.

The invention according to claim 2 is characterized in that the void in the filled concrete portion in the steel pipe is formed of an iron pipe, and a metal material having a high thermal conductivity is interposed between the steel pipe filled with the heat absorbing material and the steel pipe. In addition, the contact area between the steel pipe and the cooling section made of the heat absorbing material is increased to promote the temperature drop of the steel pipe.

The invention of Item 3 uses water as a heat-absorbing material filled in the gap, and provides a convection water channel in which the gap is connected to a water storage tank and upper and lower portions of the gap by piping. Water in the concrete filled inside the steel pipe (Mizumichi)
When the steel pipe is exposed to the flame, the water is naturally convected by using the same water to allow the cooling water to reach the part exposed to the flame, and the temperature of the steel pipe concrete structural member becomes excessively high. It is something that does not become. In addition, a damping effect by the sloshing action of the water stored in the water storage tank is exhibited.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the convection channel is provided near the inner surface of the steel pipe and at the center of the member and the convection water channel is connected at the lower layer portion. It is intended to deter the rise more effectively.

(Example) Hereinafter, the present invention will be described with reference to an illustrated example.

14 and 15 show cross sections of a conventional steel pipe concrete column provided with a fire-resistant coating, FIG. 14 shows a case where a circular steel pipe is used for the steel pipe (p), and FIG. (P) shows the case where a square steel pipe is used. In the figure, (q) is the concrete filled in the steel pipe, and (r) is the refractory coating.

FIGS. 1 to 4 show cross sections of a steel pipe concrete column member without a fire-resistant coating, and FIGS. 1 and 2 respectively show a circular steel pipe (1) and a filled concrete (2) in a square steel pipe (1). At a position in contact with the inner surface of the steel pipe (1) at
FIG. 3 and FIG. 4 show a case where a void (3) having a circular cross section for passing cooling water as a heat absorbing material is provided, and FIG. 3 and FIG. 4 respectively show a circular steel pipe (1) and a concrete filled in a square steel pipe (1). The case where the gap (3) is provided at the center of the cross section of (2) is shown.

In the above embodiment, since there is no refractory coating material,
In the event of a fire, the temperature of the surface of the steel pipe (1) directly exposed to the flame rises, but the water present in the void (3) of the filled concrete part (2) in the steel pipe (1) absorbs heat, The temperature rise on the surface of the steel pipe (1) is delayed.

In addition to water, silica gel, ettringite, or the like is used as a heat absorbing material.

In this case, the larger the contact area of the water of the gap (3) with the steel pipe (1), and the larger the gap area and the larger the amount of water in the gap (3), the more effective the prevention of temperature rise of the concrete steel pipe member. However, there is a problem that the proof stress of the member is reduced. That is, the fact that the contact area of the pore water is large means that the contact area between the steel pipe and the concrete is small. For this reason, the integrity of the steel pipe and the filled concrete is reduced, and as a result, the strength of the member is reduced. In addition, the fact that the void area is large means that the cross-sectional area of the concrete is reduced accordingly.

FIGS. 5 and 6 show a gap between the square and circular steel pipes (1) by using a corrugated cross-section member (4) such as a deck plate or a keystone plate that is frequently used as a form of a floor plate. 3) is an example in which the contact area of the pore water is increased without lowering the member yield strength. In this case, since the gap member is reinforced with the corrugated cross-section member (4), the member strength does not decrease.

Since the water in the gap (3) is usually supplied from a water tank installed on the top, the water pressure of the gap water is generally considerably high. In the example of the US steel building, since the water pressure is applied to the steel pipes entirely, the column is divided every 16 floors by the water pressure limit.

In the case of the embodiment shown in FIGS. 1 and 2, since the portion where the water pressure acts is partial, the stress of the steel pipe due to the water pressure is very small. When a void (3) is provided at the center of the steel pipe (1) as shown in FIGS. 3 and 4, the filled concrete (2) can also bear the water pressure. This has the advantage that the water pressure applied to the steel pipe is further reduced as compared with the case where the steel pipe is in contact with the inner surface.

However, as the water pressure increases further, other precautions need to be taken into account. FIGS. 7 and 8 show an embodiment in which an iron pipe (5) is used in the gap to prevent this water pressure. In FIG. 7, the iron pipe (5) through which the cooling water passes and the steel pipe (1) are shown. ) Is provided with a metal material (6) having a high thermal conductivity such as iron or copper to increase the contact area with the steel pipe.

When the pore water boils and evaporates, the temperature inside the steel pipe also rises. For this reason, when the pore water boils and evaporates and the surface of the steel pipe rises above a specified value, as shown in the above-mentioned embodiment in the US steel building, a water tank is installed at the top of the layer. Connect the upper and lower parts of each pillar to ensure that even if the pillars are exposed to the flame and the water temperature of that part rises, the part exposed to the flame by convection always has cooling water and the pillar temperature exceeds the specified value It is necessary to avoid becoming.

In the case of the cross section as shown in FIGS. 1 to 4, there is a possibility that the pore water may boil and evaporate early,
It is necessary to install a water storage tank (a) at the upper part of the bed and connect the upper and lower parts of each column with upper and lower pipes (c) and (d) to construct a convection channel that generates natural convection. As shown in FIGS. 9 and 10, when the gaps (3) and (3 ') are provided at a position near the inner surface of the steel pipe (1) and at the center of the member, as shown in FIGS. It is sufficient to connect the tops and fill the tops with water.

In other words, during a fire, the pillar members are heated from the surface,
The temperature of the water in the gap (3) rises earlier than the water in the gap (3 '). However, if the gap (3) and the gap (3 ') are connected at the lowermost layer in the same column cross section, the water in the gap naturally flows from (3') to (3) and is close to the column surface. This is because the cooled water comes to the space (3).

Therefore, in the case of FIG. 9 and FIG. 10, the piping at the lower part of the column as implemented in the US steel building can be omitted, which is economical.

FIG. 11 schematically shows the system in this case, where (7) is a water storage tank installed in the upper layer, (8) is a beam member, and (9) is a gap (3) and a gap ( 3 ') is a gap provided in the upper and lower layers of the pillar for connecting
0) is a ventilation hole for letting out evaporated water.

In this case, a water tank is installed at the top of the layer to connect the columns, and the purpose is to absorb the heat applied to the columns using natural convection of water. Since the heat capacity of the concrete itself filled into the concrete itself is high, in the case of simple fireproofing in which it is only necessary to withstand a fire of about one hour, if a material having a high endothermic property, such as ettringite, is filled in the voids, the water storage tank The column temperature can be kept below the specified value without refilling with water, and the embodiment includes such a case.

Although the above-described embodiment is mainly directed to a column member, the present invention can be applied to a beam member by a similar method. Twelfth
Fig. 13 and Fig. 13 show cross sections when the present invention is applied to a beam member. Fig. 12 shows a case where a rectangular steel pipe (1 ') is used for a beam member. This is an example in which a steel pipe (1 ″) is used. In the figure, (3) is a void portion, (2)
Is concrete and (11) is floorboard.

(Effects of the Invention) According to the present invention, a void portion is provided in a filled concrete portion in a steel pipe in a steel pipe concrete structural member, and the void portion is filled with a heat absorbing material, so that fireproof coating of the steel pipe concrete structural member is omitted. Can be economical.

When water is used as the heat absorbing material, the water is filled in the voids, so that the water pressure only partially acts, and the stress acting on the steel pipe by the water pressure is the same as in the case of the conventional water-cooled steel pipe method. In particular, when a gap is provided at the center of the steel pipe, the filled concrete can also bear the water pressure, so that the water pressure acting on the steel pipe is negligible.

Also, even if the columns are separated by the water pressure limit as in the US steel building, the separation interval can be longer than in the US steel building.

Further, according to the present invention, the filled concrete also bears the vertical force and the horizontal force, and the thickness of the steel pipe can be reduced. Even if the temperature of the steel pipe rises due to a fire and the proof stress of the steel pipe decreases, the vertical load can be supported by the filled concrete.

Furthermore, the gap may be very small, and there is almost no risk of lowering the yield strength of the member. Further, since the gap is small, the amount of water used can be much smaller than that of the conventional water-cooled steel pipe method. .

Further, in the conventional water-cooled steel pipe method, it is necessary to add an anticorrosive to water in order to prevent corrosion of the steel pipe. In the case of the present invention, however, the concrete filled in the steel pipe is alkaline and rusts the steel pipe. There is no need to add corrosion inhibitors to the water.

The invention according to claim 2 is characterized in that the void portion provided in the filled concrete portion in the steel pipe is constituted by an iron pipe provided close to the steel pipe, and a metal material having high conductivity is interposed between the steel pipe and the steel pipe. As a result, water pressure is not applied to the steel pipe, and the thickness of the steel pipe can be reduced.

The invention according to claim 3 uses water as a heat-absorbing material provided in the gap, and provides a convection water channel in which the gap is connected to a water storage tank and upper and lower portions of the gap by piping so that water is naturally generated in a fire. Of the steel pipe concrete structural member so that the temperature of the steel tubular concrete structural member does not rise excessively. In addition, the sloshing phenomenon of water in the water storage tank can exert a damping effect on the building.

According to a fourth aspect of the present invention, in the third aspect of the present invention, a void portion is provided near the inner surface of the steel pipe and at the center of the member, and a convection water channel is provided at a lower portion to prevent an excessive rise in the temperature of the steel pipe concrete structural member. , Can be more effectively suppressed.

[Brief description of the drawings]

1 to 10 are cross-sectional plan views each showing an embodiment in which a fire-resistant structure having a fire-resistant coating on a steel pipe concrete structural member is applied to a column member, and FIG. 11 is a schematic view of another embodiment of the present invention. FIG. 11A and FIG. 11B are arrows A-
12A and 13 are longitudinal sectional views showing each embodiment in which the present invention is applied to a beam member, and FIGS. 14 and 15 are conventional steel pipe concretes, respectively. FIG. 16 is a cross-sectional plan view of a structural member, and FIG. 16 is a perspective view showing a fire-resistant structure of a steel pipe concrete column by a conventional water-cooled steel pipe method. (1) ... steel pipe, (2) ... filled concrete, (3) ... void, (5) ... iron pipe, (6) ... metal material with high thermal conductivity, (7) ... water tank , (9) ... voids, (10) ... vents.

Claims (4)

(57) [Claims] 1. A fire-resistant structure with a non-fireproof coating in a steel pipe concrete structural member in which a void is provided in a concrete portion filled in a steel pipe in the steel pipe concrete structural member, and the void is filled with a heat absorbing material. 2. The steel pipe according to claim 1, wherein the gap in the filled concrete portion is formed of an iron pipe provided adjacent to the steel pipe, and a metal material having a high thermal conductivity is interposed between the steel pipe and the steel pipe. A fire-resistant structure having a fire-free coating on the steel tubular concrete structural member according to claim 1. 3. A convection water channel, wherein water is used as a heat absorbing material to be filled in said gap, and said gap, a water storage tank, and upper and lower portions of said gap are connected by piping. A refractory structure with a non-refractory coating in the steel tubular concrete structure described. 4. The convection channel according to claim 3, wherein water is used as a heat-absorbing material to be filled in said gap, and said gap is provided near an inner surface of a steel pipe and in a central portion of a member and connected in a lower layer portion. Fireproof structure with non-fireproof coating on steel tube concrete structure.