JP2012237162A - Column structure and construction method of column structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a column structure having a columns member which is subject to high axial force and made of ultra-high strength fiber reinforced concrete, which solves fireproof problem with excellent workability, having an integrated fireproof layer; and a construction method of the column structure.SOLUTION: A fireproof layer 9 is provided on the circumference of a core portion 7 made of ultra-high strength fiber reinforced concrete. A low-rigidity layer 13 made of resin is provided between the core portion 7 and the fireproof layer 9. At least one place at the junction of a bearing plate 5 above the core portion 7 and the fireproof layer 9, the junction of a bearing plate 5 below the core portion 7 and the fireproof layer 9, and the intermediate portion of the fireproof layer 9 is provided with a slit 11 as a disconnection part for not transmitting axial force to the fireproof layer 9. The core portion 7 is made of ultra-high strength fiber reinforced concrete containing steel fiber, carbon fiber, glass fiber, or the like. The fireproof layer 9 is made of polypropylene fiber reinforced concrete. The low-rigidity layer 13 is made of, for example, a resin having latent heat effect.

Description

  The present invention relates to a column structure and a method for constructing the column structure.

  Conventionally, in underground structures such as road tunnels, when the depth is deep or the cross section is flat, the cross section is divided into a plurality of parts by an intermediate wall, an intermediate pillar, etc. in order to resist earth pressure. The middle pillar is a circular or rectangular pillar, and is a member that is required to have deformation performance that resists overburden pressure at all times and can follow the deformation of the tunnel during an earthquake.

A steel pipe, a concrete-filled steel pipe (hereinafter referred to as CFT), or the like is used for the middle column. In recent years, ultra-high-strength fiber reinforced concrete (hereinafter referred to as UFC) whose compressive strength has been developed at home and abroad exceeds 150 N / mm ² has also been applied. In order to ensure the visibility of the driver, it is preferable that the middle pillars of the lane merge part of the road tunnel are arranged with a gap as much as possible, and the pillars have a smaller cross section. The middle column using ultra-high-strength fiber reinforced concrete is superior in that it can take advantage of its strength to increase the interval between columns and reduce the column cross section.

  On the other hand, in road tunnels, securing fire resistance in the event of a fire is also important. For this reason, conventionally, a fireproof panel, fireproof coating, fireproof mortar, etc. are given to the middle pillar using a steel pipe or CFT.

  In addition, concrete materials such as UFC may peel off or explode from the surface in the event of a fire due to an increase in the expansion pressure of water vapor contained in the interior and the occurrence of unsteady thermal stress. It has become clear that a phenomenon such as that is likely to occur (see, for example, Patent Document 1). Therefore, in the middle pillar using UFC, there is a concern that the member peels and explodes at the time of a fire, and the progress of this causes the member cross-section to be reduced to reduce the cross-sectional yield strength and to collapse.

  In addition to fire-resistant panels, fire-resistant paint, fire-resistant mortar, etc., as a fire-proof measure for the middle pillar using UFC, the cross-section of the pillar member is made larger than the size required for the structure to the extent that it will be damaged by a fire or other damage There is a way.

JP 2003-300205 A

  However, a fireproof panel used as a fireproof measure is generally expensive even in a flat product. When it is applied to the middle pillar, it becomes a cylindrical member divided into a half or a plurality of parts, which tends to be more expensive. In addition, the treatment of the seam is important, and there is a concern that a flame may enter from a gap between adjacent refractory panels when a fire breaks out and a sufficient fire resistance performance cannot be ensured.

  The fire-resistant paint used for fire-resistant coating forms a heat insulating layer by foaming 20 to 30 times by the heat of the fire on the surface of the structural member as a base layer. Although fireproof coating is effective as a fireproofing measure for steel, it is not suitable for concrete because the foamed layer easily peels off. Although attempts have been made to improve these problems, even if the problem of peeling is solved, the overcoat material for maintaining the fireproof performance in fireproof coating deteriorates over time. In order to maintain it, it is necessary to take measures such as periodic inspections and appropriate repairs or repainting after construction.

  Fire-resistant mortar is a material that forms a fire-resistant coating layer on the surface of a member by spraying or injecting mortar made of a fire-resistant coating material onto the surface of a pillar member or filling it into a mold to cure the mortar and form a fire-resistant layer It is. Since refractory mortar contains a lot of air bubbles and is a low-strength material, after it is cured by spraying the pillar member in advance, this pillar member is lifted or built, that is, in a factory or the like. A construction method in which a member in which a fireproof layer and a column member are integrally formed is carried into a tunnel and installed is impossible. Therefore, it is necessary to perform construction by spraying after building the pillar members, and the work process at the site will be prolonged.If the spraying plant is placed in a narrow tunnel site, the spraying material such as cement and supply water must be carried in. There is a disadvantage of not becoming. Furthermore, considerable dust is generated at the time of spray construction, and there is a problem that it takes time to clean the dropped material. There is also a problem that the spraying method cannot give design properties.

  In a pillar member made of high-strength concrete in which a refractory layer is integrally formed, synthetic fiber such as polypropylene is mixed into high-strength concrete as a measure for preventing explosion. In UFC as well, it is possible to improve the fire resistance by mixing resin fibers such as polypropylene, but there is a problem that compressive strength decreases when resin fibers are mixed. Further, in order to uniformly diffuse the steel fibers and the organic fibers, a high degree of management is necessary for the kneading during production. Furthermore, the explosion prevention effect in UFC is not sufficient compared to high-strength concrete.

  When the refractory layer is integrated with the column member, high-axial compressive stress is also generated in the refractory layer. Since the fire-resistant layer is not considered a structural member, there is no problem even if a compressive stress level exceeding the allowable stress level is applied, but in the state where the axial compressive stress is generated, it is easy to peel off or explode during a fire. There's a problem.

  The present invention has been made in view of the above-mentioned problems, and its object is to solve the problem of fire resistance in applying ultra high strength fiber reinforced concrete to a column member on which high axial force acts. An object of the present invention is to provide a column structure with excellent workability and a fire-resistant layer and a method for constructing the column structure.

  In order to achieve the above-mentioned object, the first invention comprises a core portion made of ultra-high strength fiber reinforced concrete, and a fireproof layer provided around the core portion, and is provided above the core portion. Axial force is not transmitted to the refractory layer in at least one of a joint portion between the bearing plate and the refractory layer, a joint portion between the bearing plate and the refractory layer below the core portion, and an intermediate portion of the refractory layer. A pillar structure characterized in that a slit or a rim cutting portion made of a low-rigidity material is provided.

  In the first invention, the joint portion between the bearing plate and the fireproof layer above the core portion, the joint portion between the bearing plate and the fireproof layer below the core portion, and the intermediate portion (near the center in the vertical direction) of the fireproof layer. At least one of them is provided with a slit or an edge cut portion made of a low-rigidity material. Thereby, axial force is not transmitted to the fireproof layer from the upper and lower bearing plates of the core part, and the risk of explosion at the time of fire can be reduced.

In 1st invention, you may further provide the resin-made low-rigidity layer provided between the said core part and the said fireproof layer.
By providing a low-rigidity layer, the transmission of axial force from the core to the refractory layer can be prevented more reliably, and the occurrence of compressive stress near the center of the refractory layer can be prevented, reducing the risk of explosion in the event of a fire. Further reduction can be achieved.

When a low-rigidity layer is further provided, a hollow portion may be provided in the core portion, and the core portion may have a hole that communicates the hollow portion and the low-rigidity layer. Moreover, the said fireproof layer may have a hole which connects the said low-rigidity layer and the surface of the said fireproof layer.
By providing a hole that connects the hollow portion and the low-rigidity layer, or a hole that connects the surface of the low-rigidity layer and the refractory layer, the pressure when the material of the low-rigidity layer evaporates due to heating is reduced. Can be missed.

For example, organic fibers are embedded in the fireproof layer. The organic fiber is a three-dimensional fiber fabric or the like.
By embedding a resin having a small elastic modulus, the degree of compressive stress of the refractory layer can be made small, and explosion during a fire can be suppressed. In addition, by using a three-dimensional fiber fabric, a hole through which the organic fiber melts and escapes water vapor in the event of a fire is formed, and peeling and explosion of the core portion can be suppressed.

  According to a second aspect of the present invention, there is provided a step (a) of laying a three-dimensional fiber fabric using organic fibers on the inner surface of a mold, and ultrahigh-strength fiber reinforced concrete is introduced into the mold, and the ultrahigh strength is obtained by centrifugal molding. A method for constructing a column structure, comprising: a step (b) of integrally forming a fire-resistant layer in which a paste component of strength fiber-reinforced concrete is infiltrated into the three-dimensional fiber fabric and a core portion. .

  In the second invention, after laying a three-dimensional fiber fabric using organic fibers, ultra-high-strength fiber-reinforced concrete is put into a mold and centrifugally molded. Thereby, the fireproof layer which penetrated the solid fiber fabric with the paste component of the ultra high strength fiber reinforced concrete and the core portion can be integrally formed.

  According to the present invention, in applying ultra-high-strength fiber reinforced concrete to a column member on which a high axial force acts, the column structure in which the problem of fire resistance is solved, the workability is excellent, and the fire-resistant layer is integrated, and A method for constructing a column structure can be provided.

The figure which shows the outline of pillar structure 1 Sectional view of pillar structure 1a Sectional view of column structure 1b Sectional view of column structure 1c Sectional view of column structure 1d Sectional view of column structure 1e Vertical sectional view of column structure 1f

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an outline of the column structure 1. FIG. 1A is an elevation view of the column structure 1. FIG. 1B is a cross-sectional view of the column structure 1. FIG. 1B is a cross-sectional view taken along arrow AA shown in FIG.

  As shown in FIG. 1, the column structure 1 includes a pedestal portion 3, a bearing plate 5, a core portion 7, a fireproof layer 9, and the like. The pedestal part 3 is provided above and below the core part 7. The support plate 5 is provided at the joint between the pedestal 3 and the core 7. The refractory layer 9 is provided around the core portion 7.

The core portion 7 is made of ultra high strength fiber reinforced concrete. The core part 7 preferably contains UFC, which contains steel fiber, carbon fiber, glass fiber, etc., and exhibits a compressive strength of 100 to 250 N / mm ² and a bending tensile strength of 10 to 40 N / mm ² .

  The fireproof layer 9 is preferably made of polypropylene fiber reinforced concrete (hereinafter referred to as PP concrete) or the like. In general, when polypropylene short fibers are mixed as organic fibers for the purpose of preventing explosion, those having a length of about 10 mm to 50 mm and a diameter of about 5 to 500 μm are used.

  At least one of the joints between the upper and lower pressure bearing plates 5 of the core portion 7 and the refractory layer 9 is provided with a slit 11 that is an edge cut portion for preventing axial force from being transmitted to the refractory layer 9. By providing the slit 11, the compressive stress level does not act on the upper and lower end portions of the refractory layer 9.

  When the column structure 1 shown in FIG. 1 is constructed, it is preferable to manufacture the core portion 7 and the refractory layer 9 as a precast member in a secondary product factory, and carry them in the field and install them. If PP concrete is used for the production of the refractory layer 9, the manufacturability is high, and the possibility of corner breakage during transport of the precast member is low.

  As described above, according to the first embodiment, the slits 11 are provided in the joint portion between the upper and lower bearing plates 5 of the core portion 7 and the refractory layer 9, whereby the compressive stress degree is applied to the upper and lower end portions of the refractory layer 9. No longer works and can suppress explosions in the event of a fire.

  When building the column structure 1, it is not necessary to ensure the integrity of the refractory layer 9 and the core portion 7. Rather, the integrity of the refractory layer 9 and the core portion 7 is not reliable, and if the axial force does not act on the refractory layer 9, the risk of explosion during a fire can be reduced.

  Next, a second embodiment will be described. FIG. 2 is a cross-sectional view of the column structure 1a. The structure and material of the pillar structure 1 a are substantially the same as those of the pillar structure 1 of the first embodiment, but a resin-made low-rigidity layer 13 is provided between the refractory layer 9 and the core portion 7.

The elastic modulus of UFC used for PP concrete used for the fireproof layer 9 and the core part 7 is about 30-45 kN / mm < ² >. In general, the elastic modulus of the resin used for the low-rigidity layer 13 is one digit or more smaller than this. A slit is provided at the joint between the refractory layer 9 and the bearing plate to prevent the compressive stress from acting on the upper and lower ends of the refractory layer 9, and at the same time, a material having a small elastic coefficient is used as the low rigidity layer 13 to form the refractory layer 9 and the core. By interposing it with the part 7, the degree of compressive stress of the refractory layer 9 can be made small throughout the height direction of the column. Note that the low-rigidity layer 13 may have a structure in which the refractory layer 9 and the core portion 7 slide.

  For the low-rigidity layer 13, a material that exhibits a latent heat action (hereinafter referred to as a latent heat material) may be used. In this case, the fire resistance can be improved by utilizing the latent heat of the latent heat material, that is, the heat of fusion / heat of evaporation.

  As an example of the latent heat material, a high molecular compound having a thermal decomposition temperature lower than 450 ° C. such as camphor, naphthalene, or sulfur is known. Since the UFC used for the core portion 7 performs steam curing in curing, the melting point of the latent heat material used for the low-rigidity layer 13 needs to be 100 ° C. or higher. Examples of a material that satisfies this are polyethylene and polypropylene.

  By interposing the above-described latent heat material as a thin low-rigidity layer 13 between the refractory layer 9 and the core portion 7, it is possible to slow down the temperature rise rate with respect to time during a fire. In the process in which the column structure 1a is exposed to fire and the temperature rises from the surface toward the inside, the latent heat material of the low-rigidity layer 13 disposed at the boundary between the refractory layer 9 and the core portion 7 is heated. It melts and vaporizes. The latent heat material absorbs heat as the state changes during melting and vaporization, and decelerates the temperature increase rate of the UFC in the core portion 7. Moreover, since a void layer is formed between the refractory layer 9 and the surface of the core portion 7 due to the dissipation of the latent heat material, the effect of suppressing an increase in the water vapor pressure in the core portion 7 is also exhibited. With such an action, if a latent heat material is used, the necessary thickness of the fireproof layer 9 can be reduced.

  The column structure 1a can be constructed by centrifugal molding as follows. First, PP concrete or the like is put into a centrifugal mold, and the refractory layer 9 having a predetermined thickness is formed by centrifugal molding. After this hardens or condenses, the low-rigidity layer 13 is formed by introducing a latent heat material or laying a sheet-like material. Finally, UFC is added and centrifugal molding is performed to form the core portion 7. Design can also be imparted by making the inner surface of the mold form uneven.

  When constructing the column structure 1a, the core portion 7 and the refractory layer 9 may be manufactured as a precast member in a secondary product factory. In this case, the column structure 1a is constructed by carrying the sheet material forming the core portion 7, the refractory layer 9, and the low-rigidity layer 13 which are precast members to the site.

  Thus, in the second embodiment, the low-rigidity layer 13 is provided between the fireproof layer 9 and the core portion 7. When the axial compressive force acts on the column member 1 a via the bearing plate 5, a compressive stress is generated in the core portion 7. Compressive stress does not act in the vicinity of the end if only the slits 11 are provided at the upper and lower ends of the refractory layer 9, but compressive stress is also generated in the refractory layer 9 as the distance from the upper and lower ends increases. By providing the low-rigidity layer 13, the degree of axial compressive stress introduced into the core portion 7 is not transmitted to the outer refractory layer 9, and explosion can be suppressed during a fire.

  Next, a third embodiment will be described. FIG. 3 is a cross-sectional view of the column structure 1b. The structure and material of the pillar structure 1b are substantially the same as those of the pillar structure 1a of the second embodiment, but a fine hole 17 is provided in the core part 7b corresponding to the core part 7. The hole 17 communicates the hollow portion 15 of the core portion 7 b with the low rigidity layer 13. The hole 17 is formed, for example, when the core portion 7b is manufactured.

In the pillar structure 1b, as in the pillar structure 1a of the second embodiment, the latent heat material of the low-rigidity layer 13 disposed at the boundary between the refractory layer 9 and the core portion 7b is heated and melted in the event of a fire. Vaporize. The holes 17 are provided for releasing pressure when the latent heat material of the low rigidity layer 13 is vaporized. The hollow portion of the core portion 7b is structured to communicate with the outside through upper and lower attachment portions. In the column structure 1b, water may be stored in the hollow portion 15 of the core portion 7b, and the heat of vaporization when it evaporates in the event of a fire may be used as latent heat. The pressure generated by the vaporization of water is released from the hollow portion 15 to the outside through the upper and lower mounting portions.

  When constructing the column structure 1b, for example, the core portion 7b having the holes 17 and the refractory layer 9 are manufactured as precast members at the secondary product factory. And the sheet | seat material which forms the core part 7b which is a precast member, the fireproof layer 9, and the low-rigidity layer 13 is carried in the field, and the pillar structure 1b is constructed | assembled.

  Thus, in the third embodiment, the hole 17 that communicates the hollow portion 15 of the core portion 7b and the low-rigidity layer 13 is provided. Thereby, at the time of a fire, the pressure at the time of the latent heat material of the low-rigidity layer 13 being heated and vaporized can be reliably escaped from the hole 17, and explosion can be suppressed.

  Next, a fourth embodiment will be described. FIG. 4 is a cross-sectional view of the column structure 1c. The structure and material of the column structure 1c are substantially the same as those of the column structure 1a of the second embodiment, but a fine hole 19 is provided in the refractory layer 9c corresponding to the refractory layer 9. The hole 19 communicates the surface of the refractory layer 9 c and the low rigidity layer 13. The hole 19 is formed, for example, when the refractory layer 9c is manufactured.

  In the pillar structure 1c, as in the pillar structure 1a of the second embodiment, the latent heat material of the low-rigidity layer 13 disposed at the boundary between the refractory layer 9c and the core portion 7 is heated and melted in the event of a fire. Vaporize. The hole 19 is provided to relieve pressure when the latent heat material of the low rigidity layer 13 is vaporized. In the column structure 1c, water may be stored in the hollow portion 15 of the core portion 7, and the heat of vaporization when it evaporates in the event of a fire may be used as latent heat. The pressure generated by the vaporization of water is released from the hollow portion 15 to the outside through the upper and lower mounting portions.

  When constructing the column structure 1c, for example, the refractory layer 9c having the core portion 7 and the hole 19 is manufactured as a precast member in the secondary product factory. And the sheet | seat material which forms the core part 7 which is a precast member, the fireproof layer 9c, and the low-rigidity layer 13 is carried in the field, and the pillar structure 1c is constructed | assembled.

  Thus, in the fourth embodiment, the hole 19 that communicates the surface of the refractory layer 9c and the low-rigidity layer 13 is provided. Thereby, at the time of a fire, the pressure at the time of the latent heat material of the low-rigidity layer 13 being heated and vaporized can be reliably escaped from the hole 19, and explosion can be suppressed.

  Next, a fifth embodiment will be described. FIG. 5 is a cross-sectional view of the column structure 1d. The structure of the pillar structure 1d is substantially the same as the pillar structure 1 of the first embodiment, but the core part 7d corresponding to the core part 7 and the fireproof layer 9d corresponding to the fireproof layer 9 are integrally formed. The The core part 7d is made of UFC. The fireproof layer 9d is embedded with a three-dimensional fiber fabric made of organic fibers having a small diameter. As the three-dimensional fiber fabric, for example, one formed into a three-dimensional mesh shape like a dried fiber of a plant loofah, or a product in which fibers are wound in a spiral loop in a three-dimensional network structure is used.

  In the pillar structure 1d, in the event of a fire, the three-dimensional fiber fabric embedded in the refractory layer 9d melts to form a hole through which water vapor that explodes the core portion 7d is released. As the material for the three-dimensional fiber fabric, an organic material such as polypropylene, polyvinyl alcohol, or vinylidene is preferable as a material having a relatively low melting / evaporation temperature. For example, the weight residual ratio of polypropylene and polyvinyl alcohol is 15 to 20%, which is preferable. Since polyvinyl chloride and acrylic fibers have a weight residual ratio exceeding 30%, a sufficient explosion resistance effect cannot be expected.

  The material of the three-dimensional fiber fabric is not only reduced in volume so that it becomes a water vapor loophole, but the amount of heat received by heating is used for changes such as melting, and the temperature of the refractory coating is equal to the amount of heat used for the change. It is more preferable that the material can suppress the rise. As such an organic material, synthetic resin, rubber foam or the like can be used. Specific examples include polypropylene, polystyrene, polyethylene, polyethylene-vinyl acetate copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, natural rubber, and synthetic rubber.

  The fiber diameter of the three-dimensional fabric is preferably 5 to 500 μm. If the diameter is too small, it is difficult to form pores having a preferable size for the water vapor path. If the diameter is too large, sufficient resistance to peeling / explosion of the core portion 7d during a fire cannot be expected.

  The fiber may not be a single fiber, but may be a bundle of thin fibers processed into a three-dimensional fabric. The fibers that are not tightly bundled are loosened moderately due to the flow or vibration of the paste component after the UFC placement of the core portion 7d, and the fibers are dispersed. Further, in order to ensure a predetermined thickness without crushing the three-dimensional fiber during centrifugal molding, it may be integrated with a metal three-dimensional fiber.

  When the column structure 1d is constructed, a three-dimensional fiber fabric processed into a cylindrical shape is laid on the inner surface of a mold for centrifugal molding, and UFC is charged and compacted. Thereby, the fireproof layer 9d and the core portion 7d in which the paste component penetrates into the voids of the three-dimensional fiber fabric are integrally formed. Alternatively, a three-dimensional fiber fabric is laid on the inner surface of the mold for centrifugal molding, and UFC is charged and compacted. After the fire-resistant layer 9d in which the paste component has penetrated into the three-dimensional fiber fabric is cured, the UFC is reintroduced inside the fire-resistant layer 9d. The core portion 7d may be formed by charging and compacting. Design can also be imparted by providing irregularities on the inner surface of the mold for centrifugal molding.

  As described above, in the fifth embodiment, a three-dimensional fiber fabric made of organic fibers having a small diameter is embedded in the fireproof layer 9d. As a result, the three-dimensional fiber fabric melts at the time of a fire, and a hole through which water vapor that explodes the core portion 7d is formed in the fireproof layer 9d, and peeling and explosion can be suppressed.

  In the fifth embodiment, by embedding a three-dimensional fiber fabric when forming the refractory layer 9d, the fluidity at the time of kneading is improved as compared with the method of mixing organic short fibers. In addition, since the organic fiber is disposed only in the fireproof layer 9d and is not contained in the core portion 7d that supports the load, the conventional problem that the compressive strength of the structural member is reduced due to the inclusion of the organic fiber is solved. When a three-dimensional fiber fabric is made of a structure in which polypropylene fibers are heat-welded, it is resistant to acids and alkalis and is chemically stable, so that harmful substances may be eluted when placing UFC in the core portion 7d. Absent.

  Next, a sixth embodiment will be described. FIG. 6 is a cross-sectional view of the column structure 1e. The structure of the column structure 1e is substantially the same as that of the column structure 1d of the fifth embodiment, but the steel fiber 21 is disposed between the core portion 7d and the refractory layer 9d. The core part 7d is made of UFC containing steel fibers. The fireproof layer 9d is embedded with a three-dimensional fiber fabric made of organic fibers or the like having a small diameter, similarly to the column structure 1d of the fifth embodiment.

  When the column structure 1e is constructed, a three-dimensional fiber fabric processed into a cylindrical shape is laid on the inner surface of a mold for centrifugal molding, and UFC containing steel fibers is charged and compacted. As a result, the fireproof layer 9d and the core portion 7d in which the UFC paste has penetrated into the voids of the three-dimensional fiber fabric are integrally formed. At this time, since the specific gravity (7.85) of the steel fibers 21 is heavier than the specific gravity (3-4) of the UFC paste, the steel fibers 21 cannot penetrate into the voids of the three-dimensional fiber fabric and concentrate along the inner surface of the three-dimensional fiber fabric. Arranged. In a normal casting method, steel fibers are randomly oriented in the three-dimensional direction, but in the case of centrifugal molding, the steel fibers are oriented in two dimensions. Design can also be imparted by providing irregularities on the inner surface of the mold for centrifugal molding.

  Thus, in the sixth embodiment, the steel fibers 21 are concentrated and arranged along the inner surface of the three-dimensional fiber fabric. As a result, there are merits such that the bending tensile strength as a cylindrical product is improved, the toughness at the time of compressive fracture is improved, and the orientation direction is effective for preventing explosion at the time of fire.

  Note that it is also possible to reduce the amount of the steel fiber 21 during mixing, considering that only the paste component penetrates into the refractory layer 9d. In that case, there is also an advantage that mixing becomes easy.

  Next, a seventh embodiment will be described. FIG. 7 is a vertical sectional view of the column structure 1f. The structure of the columnar structure 1f is substantially the same as that of the columnar structure 1 of the first embodiment, but the slit 11 is also provided near the middle in the vertical direction of the refractory layer 9f corresponding to the refractory layer 9. When the column is long, the degree of compressive stress at the middle part of the column of the fireproof layer 9f is larger than the degree of compressive stress at the upper end and the lower end. By providing the slit 11 in the middle part of the refractory layer 9f as in the columnar structure 1f, the compressive stress level does not act on the middle part of the refractory layer 9.

  When the column structure 1f shown in FIG. 7 is constructed, it is preferable to manufacture the core portion 7 and the refractory layer 9f as precast members in a secondary product factory, and carry them in the field to install them.

  As described above, according to the seventh embodiment, the slits 11 are provided in the joint portion between the upper and lower bearing plates 5 of the core portion 7 and the fireproof layer 9f, and in the middle portion of the fireproof layer 9f, thereby providing the fireproof layer. The degree of compressive stress does not act on the upper and lower ends and the middle of 9f, and explosion can be suppressed during a fire.

  In the first to sixth embodiments, slits 11 are provided at the upper end portion and the lower end portion of the refractory layer, and in the seventh embodiment, slits 11 are provided at the upper end portion, the lower end portion and the central portion of the refractory layer. However, the slit may be provided in at least one of the upper end, the lower end, and the center. Further, a low-rigidity material having fire resistance performance may be installed in the slit 11 portion to form an edge cut portion.

  Furthermore, in the pillar structure 1b of the third embodiment, the hole 17 is provided in the core portion 7b, and in the pillar structure 1c of the fourth embodiment, the hole 19 is provided in the fireproof layer 9c. Both the core portion and the fireproof layer are provided. It is also possible to provide a hole in the upper and lower the pressure generated by vaporizing the material of the low rigidity layer 13.

  In the first to seventh embodiments, the cross section of the column structure is a hollow circle, but the shape of the cross section is not limited to this. When manufactured as a precast member, it may be a rectangle or a circle without a hollow.

  The thickness of the refractory layer is generally about 60 to 100 mm when PP concrete is used. The method of embedding a three-dimensional fiber fabric in the fireproof layer and the method of providing a low-rigidity layer between the fireproof layer and the UFC core portion can be used in combination. The thickness of the low rigidity layer is desirably about 5 to 10 mm. In this case, the thickness of the refractory layer can be further reduced.

  When constructing a column structure by combining the method of embedding a three-dimensional fiber fabric in the fireproof layer and the method of providing a low rigidity layer between the fireproof layer and the core portion made of UFC, a mold for centrifugal molding is used. A three-dimensional fiber fabric processed into a cylindrical shape is laid on the inner surface, UFC is added, and centrifugal molding is performed to form a fireproof layer having a predetermined thickness. After this has hardened or condensed, a latent heat material is added or a sheet-like material is laid to form a low-rigidity layer. Finally, UFC is added and centrifugal molding is performed to form the core portion.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

1, 1a, 1b, 1c, 1d, 1e, 1f ......... Pillar structure 3 ......... Pedestal part 5 ......... Supporting pressure plate 7, 7b, 7d ......... Core part 9, 9c, 9d, 9f ......... Refractory layer 11 ... ... Slit 13 ... ... Low rigidity layer 15 ... ... Hollow parts 17, 19 ... ... Hole 21 ... ... Steel fiber

Claims (7)

A core made of ultra high strength fiber reinforced concrete;
A refractory layer provided around the core portion;
Comprising
The refractory layer is provided in at least one of a joint portion between the bearing plate above the core portion and the refractory layer, a joint portion between the bearing plate below the core portion and the refractory layer, and an intermediate portion of the refractory layer. A pillar structure characterized by being provided with a slit for preventing axial force from being transmitted to the frame or an edge cutting portion made of a low-rigidity material.   The column structure according to claim 1, further comprising a resin-made low-rigidity layer provided between the core portion and the fireproof layer.   The column structure according to claim 2, wherein a hollow portion is provided in the core portion, and the core portion has a hole communicating the hollow portion and the low-rigidity layer.   The column structure according to claim 2 or 3, wherein the refractory layer has a hole communicating the low rigidity layer and the surface of the refractory layer.   The pillar structure according to any one of claims 1 to 4, wherein an organic fiber is embedded in the refractory layer.   6. The column structure according to claim 5, wherein the organic fiber is a three-dimensional fiber fabric. Laying a three-dimensional fiber fabric using organic fibers on the inner surface of the mold (a);
An ultra-high-strength fiber reinforced concrete is put into the mold, and a refractory layer in which the paste component of the ultra-high-strength fiber reinforced concrete is infiltrated into the three-dimensional fiber fabric is integrally formed by centrifugal molding. Step (b) to perform,
A method for constructing a column structure, comprising:

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