JP7605690B2 - Fireproof coating structure for concrete-filled steel pipe - Google Patents

Description

The present invention relates to a fire-resistant coating structure for concrete-filled steel pipes.

Structural components in which the outer surface of a steel pipe is covered with wood material are known (see, for example, Patent Documents 1 and 2).

JP 2017-089329 A JP 2019-056202 A

The technologies disclosed in Patent Documents 1 and 2 can improve the design of steel pipes by covering them with wood materials, but there is room for improvement in terms of fire resistance.

Taking the above facts into consideration, the present invention aims to improve the design quality of concrete-filled steel pipes while also improving their fire resistance.

The fire-resistant coating structure for a concrete-filled steel pipe in the first embodiment comprises a wood-based fire-resistant coating material that is attached to a steel pipe filled with concrete inside and provides fire-resistant coating to the outer surface of the steel pipe via an insulating layer.

According to the fire-resistant coating structure for a concrete-filled steel pipe according to claim 1, the inside of the steel pipe is filled with concrete. The heat capacity of this concrete increases the fire resistance of the steel pipe.

The steel pipe is also fitted with a wood fire-resistant coating. The wood fire-resistant coating provides a fire-resistant coating to the outer surface of the steel pipe. This improves the design of the steel pipe while also improving its fire resistance.

In addition, the wood fire-resistant coating material provides a fire-resistant coating to the outer surface of the steel pipe via an insulating layer. This insulating layer can further improve the fire resistance of the steel pipe.

The second aspect of the fire-resistant coating structure for a concrete-filled steel pipe is the fire-resistant coating structure for a concrete-filled steel pipe of the first aspect , which is provided with a screw member protruding from the outer surface of the steel pipe, and the wood-based fire-resistant coating material is attached to the steel pipe using the screw member with a gap as the insulating layer between the wood-based fire-resistant coating material and the outer surface of the steel pipe.

According to the fire-resistant coating structure for a concrete-filled steel pipe relating to the second aspect , the wood-based fire-resistant coating material is attached to the steel pipe using a screw member protruding from the outer surface of the steel pipe, leaving a gap between the wood-based fire-resistant coating material and the outer surface of the steel pipe as an insulating layer.

In this way, by leaving a gap between the wood fire-resistant coating material and the outer surface of the steel pipe as an insulating layer, the gap can absorb installation errors of the wood fire-resistant coating material while improving the fire resistance of the steel pipe.

The fire-resistant coating structure for a concrete-filled steel pipe in the third aspect is the fire-resistant coating structure for a concrete-filled steel pipe in the first aspect , and comprises an engaged portion provided on the wood fire-resistant coating material and facing the outer surface of the wood fire-resistant coating material, and an engaging portion provided on the outer surface of the steel pipe and engaging with the engaged portion.

According to the third aspect of the fire-resistant covering structure for a concrete-filled steel pipe, the wood-based fire-resistant covering material is provided with an engaged portion that faces the outer surface of the wood-based fire-resistant covering material. Also, an engaging portion is provided on the outer surface of the steel pipe. By engaging this engaging portion with the engaged portion of the wood-based fire-resistant covering material, the wood-based fire-resistant covering material can be easily attached to the steel pipe.

The fire-resistant coating structure for a concrete-filled steel pipe in the fourth aspect is a fire-resistant coating structure for a concrete-filled steel pipe in any one of the first to third aspects , which is provided with a positioning protrusion that protrudes from the outer surface of the steel pipe and is inserted into a positioning hole formed on the inner surface of the wood-based fire-resistant coating material.

According to the fourth aspect of the fire-resistant covering structure for a concrete-filled steel pipe, a positioning protrusion is protruded from the outer surface of the steel pipe. By inserting this positioning protrusion into a positioning hole formed on the inner surface of the wood fire-resistant covering material, the wood fire-resistant covering material can be easily positioned relative to the steel pipe.

The manufacturing method for wood fire-resistant coating material of the fifth aspect is a manufacturing method for wood fire-resistant coating material that manufactures a cylindrical wood fire-resistant coating material that is attached to a round steel pipe filled with concrete inside and provides fire-resistant coating for the outer peripheral surface of the round steel pipe via an insulating layer, and includes a cutting process for cutting the outer peripheral surface of the wood fire-resistant coating material into a circular cross-sectional shape while rotating a rotating shaft body having a plurality of split pieces formed by dividing the wood fire-resistant coating material circumferentially attached to its outer peripheral surface, and an attachment process for removing the plurality of split pieces from the rotating shaft body and attaching them to the round steel pipe.

According to the manufacturing method of the fifth aspect of the present invention, first, in the cutting step, the outer peripheral surface of the wood fire-resistant covering material is cut into a circular cross-sectional shape while rotating a rotating shaft having a plurality of divided pieces attached to its outer peripheral surface, which divide the wood fire-resistant covering material in the circumferential direction. This makes it possible to easily process the outer peripheral surface of the wood fire-resistant covering material into a circular cross-sectional shape.

Next, in the installation process, the split pieces are removed from the rotating shaft and attached to the round steel pipe. This improves the design of the round steel pipe while also improving its fire resistance.

As explained above, the present invention can improve the design of concrete-filled steel pipes while also improving their fire resistance.

FIG. 2 is a cross-sectional view showing a concrete-filled steel pipe column to which a fire-resistant coating structure for a concrete-filled steel pipe according to the first embodiment is applied. FIG. 2 is a cross-sectional view corresponding to FIG. 1 , showing a concrete-filled steel pipe column to which a modified example of the fire-resistant coating structure of the concrete-filled steel pipe in the first embodiment is applied. FIG. 2 is a cross-sectional view corresponding to FIG. 1 , showing a concrete-filled steel pipe column to which a modified example of the fire-resistant coating structure of the concrete-filled steel pipe in the first embodiment is applied. FIG. 4 is an enlarged cross-sectional view of a portion of FIG. 3 . FIG. 4 is an exploded cross-sectional view of the concrete-filled steel pipe and wood fire-resistant covering material shown in FIG. 3 . FIG. 5 is a partially enlarged cross-sectional view corresponding to FIG. 4 , showing a concrete-filled steel pipe column to which a modified example of the fire-resistant coating structure of the concrete-filled steel pipe according to the first embodiment is applied. FIG. 5 is a partially enlarged cross-sectional view corresponding to FIG. 4 , showing a concrete-filled steel pipe column to which a modified example of the fire-resistant coating structure of the concrete-filled steel pipe according to the first embodiment is applied. FIG. 5 is a partially enlarged cross-sectional view corresponding to FIG. 4 , showing a concrete-filled steel pipe column to which a modified example of the fire-resistant coating structure of the concrete-filled steel pipe according to the first embodiment is applied. FIG. 11 is a cross-sectional view showing a concrete-filled steel pipe column to which a fire-resistant coating structure for a concrete-filled steel pipe according to a second embodiment is applied. 1 is a partially enlarged cross-sectional view showing a concrete-filled steel pipe column to which a modified example of a fire-resistant coating structure for a concrete-filled steel pipe according to a second embodiment is applied. 1 is a partially enlarged cross-sectional view showing a concrete-filled steel pipe column to which a modified example of a fire-resistant coating structure for a concrete-filled steel pipe according to a second embodiment is applied. FIG. 11 is a cross-sectional view showing a concrete-filled steel pipe column to which a fire-resistant coating structure for a concrete-filled steel pipe according to a third embodiment is applied. FIG. 13 is an exploded cross-sectional view of the concrete-filled steel pipe and wood fire-resistant covering material shown in FIG. 12. FIG. 11 is a longitudinal cross-sectional view showing a concrete-filled steel pipe column to which a modified example of a fire-resistant coating structure of a concrete-filled steel pipe according to a third embodiment is applied. FIG. 11 is a cross-sectional view showing a concrete-filled steel pipe column to which a fire-resistant coating structure for a concrete-filled steel pipe according to a fourth embodiment is applied. FIG. 11 is a cross-sectional view showing a concrete-filled steel pipe column to which a modified example of a fire-resistant coating structure of a concrete-filled steel pipe according to the fourth embodiment is applied. FIG. 11 is a cross-sectional view showing a concrete-filled steel pipe column to which a modified example of a fire-resistant coating structure of a concrete-filled steel pipe according to the fourth embodiment is applied. 18 is a cross-sectional view showing the manufacturing process of the wood fire-resistant coating material shown in FIG. 17.

First Embodiment
First, the first embodiment will be described.

(Concrete-filled steel pipe column)
Fig. 1 shows a concrete-filled steel pipe column (hereinafter referred to as "CFT column") 10 to which a fire-resistant coating structure for a concrete-filled steel pipe according to the first embodiment is applied. The CFT column 10 includes a steel pipe 12 and concrete 14 filled inside the steel pipe 12.

The steel pipe 12 is, as an example, a square steel pipe. This CFT column 10 is fire-resistant coated with multiple wood fire-resistant coating materials 20. Note that the steel pipe 12 is not limited to a square steel pipe, and may be a round steel pipe.

(Wood fireproof coating material)
The multiple wood fire-resistant covering materials 20 are arranged to surround the CFT column 10. The wood fire-resistant covering materials 20 also provide fire-resistant covering to the outer surface 12A of the steel pipe 12 of the CFT column 10 via gaps 22 as a heat insulating layer.

Each wood fire-resistant coating material 20 is formed from a wood board such as CLT (Cross Laminated Timber), LVL (Laminated Veneer Lumber), laminated timber, or plywood. In addition, from the viewpoint of fire resistance, it is preferable to use a thermosetting resin-based adhesive for the adhesive used for laminated timber.

The wood fire-resistant coating material 20 functions as a fire-resistant coating material. Specifically, the wood fire-resistant coating material 20 functions as a substitute layer that provides fire-resistant coating to the CFT column 10. The substitute layer burns during a fire and forms a charred layer (thermal insulation layer), which prevents fire heat from penetrating into the CFT column 10.

The thickness (thickness) t of the wood fire-resistant coating material 20 is set appropriately according to the required fire resistance performance. More specifically, when wood (wooden material) is heated on one side, it is carbonized to 40 mm to 60 mm after one hour of heating, 70 mm to 90 mm after two hours of heating, and 100 mm to 120 mm after three hours of heating. When wood (wooden material) is heated on two sides, a 10% to 20% margin in the thickness is required, and the wood thickness of pillars, beams, etc. (thickness t of wood fire-resistant coating material 20) is set to 44 mm to 72 mm after one hour of heating, 77 mm to 108 mm after two hours of heating, and 110 mm to 144 mm after three hours of heating.

Examples of tree species (wood) used for the wood fire-resistant covering material 20 include larch, Douglas fir, and cedar. Depending on the tree species, the burning state of the outer surface (front surface) of the wood fire-resistant covering material 20 after heating may differ. For example, in the case of cedar, burning tends to continue over the entire outer surface of the wood fire-resistant covering material 20.

On the other hand, in the case of larch and Douglas fir, the outer surface 20A of the wood-based fire-resistant covering material 20 continues to burn partially, but the fire tends to stop as a whole. Therefore, larch and Douglas fir are preferred as the tree species (wood) to be used for the wood-based fire-resistant covering material 20.

The steel pipe 12 of the CFT column 10 has a high thermal conductivity. Therefore, even if partial combustion continues on the outer surface 20A of the wood fire-resistant coating material 20 during a fire, the heat of the fire is diffused throughout the steel pipe 12, suppressing localized temperature rise in the steel pipe 12. Furthermore, the concrete 14 inside the steel pipe 12 has a large heat capacity, further suppressing temperature rise in the steel pipe 12.

Therefore, when larch or Douglas fir is used for the wood fire-resistant covering material 20, even if combustion continues partially on the outer surface 20A of the wood fire-resistant covering material 20 during a fire, the fire resistance of the CFT column 10 is ensured.

(Action)
Next, the operation of the first embodiment will be described.

As shown in FIG. 1, the inside of the steel pipe 12 of the CFT column 10 is filled with concrete 14. The heat capacity of this concrete 14 increases the fire resistance of the CFT column 10.

In addition, a wood fire-resistant coating material 20 is attached to the steel pipe 12. The wood fire-resistant coating material 20 is made of wood (wood material) that has excellent design, and functions as a substitute layer that provides fire-resistant coating to the outer surface 12A of the steel pipe 12. This improves the design while also improving the fire resistance of the CFT column 10.

Furthermore, the wood fire-resistant coating material 20 provides fire-resistant coating to the outer surface 12A of the steel pipe 12 through a gap 22. This gap 22 forms an insulating layer (air layer) between the outer surface 12A of the steel pipe 12 and the outer surface 20A of the wood fire-resistant coating material 20, further improving the fire resistance of the CFT column 10.

In addition, by forming a gap 22 between the outer surface 12A of the steel pipe 12 and the inner surface 20B of the wood fire-resistant coating material 20, the gap 22 can absorb construction errors of the wood fire-resistant coating material 20. This improves the construction of the wood fire-resistant coating material 20.

In this way, in this embodiment, the workability of the wood fire-resistant coating material 20 can be improved while improving the fire resistance of the CFT column 10.

(Modification of the first embodiment)
Next, a modification of the first embodiment will be described.

In the modified example shown in FIG. 2, the wood fire-resistant coating material 20 provides fire-resistant coating to the outer surface 12A of the steel pipe 12 of the CFT column 10 via the gap 22 and metal plate 28 as an insulating layer.

Specifically, the metal plate 28 is made of a steel plate, iron plate, or the like, which has a high thermal conductivity. This metal plate 28 is pre-bonded with an adhesive in a state where it is layered on the inner surface 20B of the wood fire-resistant covering material 20. In other words, the wood fire-resistant covering material 20 and the metal plate 28 are pre-integrated into a unit. In addition, a gap 22 is formed between the metal plate 28 and the outer surface 12A of the steel pipe 12.

In this way, the wood fire-resistant coating material 20 provides fire-resistant coating to the outer surface 12A of the steel pipe 12 of the CFT column 10 via the gap 22 and the metal plate 28 as an insulating layer. As a result, if combustion continues partially on the outer surface 20A of the wood fire-resistant coating material 20 during a fire, for example, the metal plate 28 diffuses the fire heat, dispersing it throughout the steel pipe 12. As a result, localized temperature increases in the steel pipe 12 are suppressed. This improves the fire resistance of the CFT column 10.

In addition, the gap 22 creates an insulating layer (air layer) between the outer surface 12A of the steel pipe 12 and the outer surface 20A of the wood fire-resistant coating material 20, further improving the fire resistance of the CFT column 10.

Furthermore, by forming the wood fire-resistant coating material 20 and the metal plate 28 into a pre-integrated unit, workability is improved.

Next, in the modified example shown in FIG. 3, the wood fire-resistant coating material 20 provides fire-resistant coating to the outer surface 12A of the steel pipe 12 of the CFT column 10 through gaps 22 as a heat insulating layer. This wood fire-resistant coating material 20 is attached to the steel pipe 12 by a number of screw members 30 and nuts 32 protruding from the outer surface 12A of the steel pipe 12. Specifically, the screw members 30 are attached near the corners of each outer surface 12A of the steel pipe 12.

As shown in Figures 4 and 5, the screw member 30 is a stepped bolt. This screw member 30 has a threaded portion 30A and a stepped portion 30B with a larger diameter than the threaded portion 30A. The underside of the stepped portion 30B is butted against the outer surface 12A of the steel pipe 12 and joined by welding or the like. As a result, the screw member 30 is attached to the outer surface 12A of the steel pipe 12 while protruding from the outer surface 12A of the steel pipe 12.

Multiple mounting holes 24 are formed on the inner surface 20B of the wood fire-resistant covering material 20, which faces the outer surface 12A of the steel pipe 12. The mounting holes 24 are circular through-holes that penetrate both ends of the wood fire-resistant covering material 20 in the width direction in the plate thickness direction.

The diameter of the mounting hole 24 is larger than the diameter of the threaded portion 30A of the screw member 30, but smaller than the diameter of the step portion 30B. As a result, when the threaded portion 30A of the screw member 30 is inserted into the mounting hole 24, the peripheral portion of the mounting hole 24 engages with the step portion 30B, and a gap 22 is formed between the outer surface 12A of the steel pipe 12 and the inner surface 20B of the wood fire-resistant coating material 20. In other words, the step portion 30B of the screw member 30 functions as a spacer that forms the gap 22 as an insulating layer between the outer surface 12A of the steel pipe 12 and the inner surface 20B of the wood fire-resistant coating material 20.

A circular countersunk hole 26 is formed on the outer surface 20A of the wood fire-resistant coating material 20, leading to the mounting hole 24. The diameter of the countersunk hole 26 is made larger than the diameter of the mounting hole 24. A nut 32 is housed in the countersunk hole 26. By tightening the nut 32 into the threaded portion 30A of the screw member 30, the wood fire-resistant coating material 20 is removably attached to the outer surface 12A of the steel pipe 12.

A wooden plug 34 that covers and conceals the nut 32 is fitted into the countersink 26. This wooden plug 34 insulates the screw member 30 and the nut 32 and enhances the design of the outer surface 20A of the wood fire-resistant coating material 20.

The number and arrangement of the screw members 30 can be changed as appropriate. The countersunk holes 26 and wooden plugs 34 can be provided as needed and can be omitted as appropriate.

In addition, by using a stepped bolt as the screw member 30, a predetermined gap 22 can be easily formed between the outer surface 12A of the steel pipe 12 and the inner surface 20B of the wood fire-resistant coating material 20.

Furthermore, by attaching the wood fire-resistant coating material 20 to the outer surface 12A of the steel pipe 12 using the screw member 30 and nut 32, the wood fire-resistant coating material 20 can be easily replaced or dismantled.

Next, in the modified example shown in FIG. 6, the step 30B of the screw member 30 is fire-resistant coated with a heat insulating material 40 as a heat insulating layer. For example, calcium silicate board, gypsum board, rock wool, ceramic wool, wood, etc. are used as the heat insulating material 40. This suppresses the temperature rise of the screw member 30 in the event of a fire, thereby further improving the fire resistance of the CFT column 10.

Next, in the modified example shown in FIG. 7, a recess 50 is formed at one end of adjacent wood fire-resistant coating materials 20, and a protrusion 52 is formed at the other end. Then, with the protrusion 52 fitted into the recess 50, the recess 50 and the protrusion 52 are joined by a screw 54. This screw 54 reduces the gap between the ends of adjacent wood fire-resistant coating materials 20, thereby improving the fire resistance of the CFT column 10.

In addition, the screws 54 are driven into the recesses 50 and protrusions 52 through countersunk holes 56 formed on the end surface of the wood fire-resistant coating material 20. By fitting wooden plugs 58 that cover and conceal the screws 54 into the countersunk holes 56, the design of the outer surface 20A of the wood fire-resistant coating material 20 can be improved while insulating the screws 54.

Next, in the modified example shown in FIG. 8, the wood fire-resistant coating material 20 is attached to the corner of the steel pipe 12 via a bracket 60 and a heat insulating material 62 as a heat insulating layer. The bracket 60 is, for example, an L-shaped metal piece bent to fit the corner of the steel pipe 12. The end of the wood fire-resistant coating material 20 is bonded to the outer surface of the bracket 60 with an adhesive or the like. Meanwhile, the heat insulating material 62 is bonded to the inner surface of the bracket 60 with an adhesive or the like. Note that a thermosetting resin-based adhesive is preferable from the viewpoint of fire resistance.

The heat insulating material 62 is bonded to the outer surface 12A of the corner of the steel pipe 12 with adhesive or the like. For example, calcium silicate board, gypsum board, rock wool, or the like is used for this heat insulating material 62. This reduces the heat of a fire that is transferred from the bracket 60 to the corner of the steel pipe 12.

In addition, by bonding the ends of the wood fire-resistant covering material 20 to the outer surface of the bracket 60 with adhesive or the like, the mounting holes 24 (see Figure 4) of the wood fire-resistant covering material 20 can be omitted. This reduces the manufacturing cost of the wood fire-resistant covering material 20.

In addition, by attaching the wood fire-resistant coating material 20 to the corners of the steel pipe 12 via brackets 60 and insulating material 62, a gap 22 is formed as an insulating layer between the outer surface 12A of the steel pipe 12 and the inner surface 20B of the wood fire-resistant coating material 20. This further improves the fire resistance of the CFT column 10.

Second Embodiment
Next, a second embodiment will be described. In the second embodiment, the same reference numerals will be used to designate the same members as in the first embodiment, and the description thereof will be omitted as appropriate.

As shown in FIG. 9, in the second embodiment of the fire-resistant coating structure for a concrete-filled steel pipe, a wood-based fire-resistant coating material 20 is bonded to the outer surface 12A of the steel pipe 12 via a metal plate 28 as an insulating layer.

Specifically, the metal plate 28 is made of a steel plate, iron plate, or the like, which has a high thermal conductivity. This metal plate 28 is pre-bonded with an adhesive in a state where it is layered on the inner surface 20B of the wood fire-resistant covering material 20. In other words, the wood fire-resistant covering material 20 and the metal plate 28 are pre-integrated into a unit.

The metal plate 28 is superimposed on the outer surface 12A of the steel pipe 12 and adhered with an adhesive. This allows the wood fire-resistant coating material 20 to be attached to the outer surface 12A of the steel pipe 12 via the metal plate 28 as an insulating layer.

Positioning protrusions 70 are provided on both ends of the outer surface 12A of the steel pipe 12 in the width direction. The positioning protrusions 70 are formed, for example, in a plate shape using a steel plate or the like, and are arranged along the material axis direction of the steel pipe 12. The positioning protrusions 70 are welded to the outer surface 12A of the steel pipe 12 in a state where they protrude like a rib.

The positioning protrusions 70 are inserted (fitted) into groove-shaped positioning holes 72 formed in the wood fire-resistant covering material 20 and the metal plate 28. This positions the wood fire-resistant covering material 20 and the metal plate 28 relative to the outer surface 12A of the steel pipe 12 in the width direction and material axis direction of the steel pipe 12.

The positioning protrusions 70 are not limited to being rib-shaped, and may be pin-shaped. The number and arrangement of the positioning protrusions 70 can be changed as appropriate. The positioning holes 72 can be changed as appropriate depending on the shape and arrangement of the positioning protrusions 70. The positioning protrusions 70 and the positioning holes 72 can be provided as necessary, and can be omitted as appropriate.

(Action)
Next, the operation of the second embodiment will be described.

As shown in FIG. 9, the wood fire-resistant coating material 20 provides fire-resistant coating to the outer surface 12A of the steel pipe 12 of the CFT column 10 via a metal plate 28 as an insulating layer. As a result, if, for example, combustion continues partially on the outer surface 20A of the wood fire-resistant coating material 20 during a fire, the metal plate 28 diffuses the fire heat, dispersing and transmitting the fire heat to the entire steel pipe 12. As a result, localized temperature increases in the steel pipe 12 are suppressed. This improves the fire resistance of the CFT column 10.

In addition, by adhering the wood fire-resistant coating material 20 to the outer surface 12A of the steel pipe 12 via the metal plate 28, it becomes easier to adhere the inner surface 20B of the wood fire-resistant coating material 20 to the outer surface 12A of the steel pipe 12. Therefore, the adhesive strength of the wood fire-resistant coating material 20 to the outer surface 12A of the steel pipe 12 can be increased.

Furthermore, by forming the wood fire-resistant coating material 20 and the metal plate 28 into a pre-integrated unit, workability is improved.

In addition, a positioning protrusion 70 is provided on the outer surface 12A of the steel pipe 12. By inserting this positioning protrusion 70 into a positioning hole 72 formed in the wood fire-resistant covering material 20 and the metal plate 28, the wood fire-resistant covering material 20 and the metal plate 28 can be easily positioned relative to the outer surface 12A of the steel pipe 12.

Furthermore, when the wood fire-resistant coating material 20 is adhered (pressure-bonded) to the outer surface 12A of the steel pipe 12 via the metal plate 28, positional deviation of the metal plate 28 and the wood fire-resistant coating material 20 relative to the outer surface 12A of the steel pipe 12 is suppressed.

(Modification of the second embodiment)
Next, a modification of the second embodiment will be described.

In the modified example shown in FIG. 10, a gap G is formed between the ends of adjacent wood fire-resistant coating materials 20. This gap G makes it possible to absorb construction errors between adjacent wood fire-resistant coating materials 20. This improves the construction ease of the wood fire-resistant coating material 20.

In addition, filler wood 82 is fitted into the gap G via putty (fireproof putty) 80 that fills the gap G. This improves the fire resistance of the CFT column 10 while enhancing the design.

Next, in the modified example shown in FIG. 11, a corner member 84 is provided at the corner of the steel pipe 12. As an example, the corner member 84 is formed from a square steel pipe and is arranged along the material axis direction of the steel pipe 12. The corner member 84 is also arranged between the ends of adjacent wood fire-resistant covering materials 20. This corner member 84 is attached to the end faces of adjacent wood fire-resistant covering materials 20 with adhesive or screws (not shown), etc.

By providing corner members 84 at the corners of the steel pipe 12 in this way, interference between the ends of adjacent wood fire-resistant coating materials 20 is suppressed when attaching the wood fire-resistant coating material 20 to the outer surface 12A of the steel pipe 12. This improves the workability of the wood fire-resistant coating material 20.

The corner members 84 are not limited to square steel pipes, but may be, for example, square column-shaped concrete members.

Next, in the above embodiment, the wood fire-resistant coating material 20 is attached to the outer surface 12A of the steel pipe 12 via a metal plate 28 as an insulating layer. However, the insulating layer is not limited to the metal plate 28, and may be, for example, an insulating material such as a calcium silicate board, gypsum board, rock wool, or ceramic wool, or may be an adhesive (a heat-resistant adhesive such as a thermosetting resin-based adhesive). The wood fire-resistant coating material 20 may also be attached to the outer surface 12A of the steel pipe 12 via an air layer (gap) and the metal plate 28 as an insulating layer.

Third Embodiment
Next, a third embodiment will be described. In the third embodiment, the same reference numerals will be used to designate the same members as those in the first and second embodiments, and the description thereof will be omitted as appropriate.

As shown in Figures 12 and 13, in the fire-resistant coating structure for a concrete-filled steel pipe according to the third embodiment, a wood fire-resistant coating material 20 and a metal plate 28 are removably attached to the steel pipe 12 via a pair of snap fits 90.

Specifically, a pair of snap fits 90 are provided on the outer surface 12A of the steel pipe 12. The pair of snap fits 90 are spaced apart in the width direction of the outer surface 12A of the steel pipe 12, and are joined to each corner of the steel pipe 12 by welding or the like. In addition, the pair of snap fits 90 are provided in multiple sets at intervals in the material axis direction (up-down direction) of the steel pipe 12, for example.

The snap fit 90 protrudes from the outer surface 12A of the steel pipe 12 and has a claw 90A that can elastically deform in the width direction of the steel pipe 12. This claw 90A is inserted (pressed) into an insertion hole 92 formed in the wood fire-resistant covering material 20 and the metal plate 28 while elastically deforming, and is engaged with an engaged surface 94L formed on the wood fire-resistant covering material 20.

The engaged surface 94L is formed on the outer surface 20A of the wood fire-resistant covering material 20, and serves as the bottom surface of the mounting hole 94 that leads to the insertion hole 92. The engaged surface 94L faces the outer surface 20A of the wood fire-resistant covering material 20. By engaging (hooking) the claw piece 90A with this engaged surface 94L, the wood fire-resistant covering material 20 and the metal plate 28 are removably attached to the outer surface 12A of the steel pipe 12. A wooden plug 96 that covers and conceals the claw piece 90A is fitted into the mounting hole 94.

Note that the claw piece 90A is an example of an engaging portion, and the engaged surface 94L is an example of a receiving portion.

In this embodiment, the pair of claws 90A restricts the movement of the wood fire-resistant coating material 20 and metal plate 28 in the width direction relative to the outer surface 12A of the steel pipe 12. In contrast, it is difficult for the pair of claws 90A to restrict the movement of the wood fire-resistant coating material 20 and metal plate 28 in the vertical width direction (the material axis direction of the steel pipe 12) relative to the outer surface 12A of the steel pipe 12.

To address this issue, in this embodiment, a positioning protrusion 100 is provided on the outer surface 12A of the steel pipe 12. The positioning protrusion 100 protrudes like a pin from the outer surface 12A of the steel pipe 12. This positioning protrusion 100 is inserted (fitted) into a positioning hole 102 formed in the wood fireproof coating material 20 and the metal plate 28.

This limits the movement of the wood fire-resistant coating material 20 and the metal plate 28 in the vertical width direction (the material axis direction of the steel pipe 12) and horizontal width direction relative to the outer surface 12A of the steel pipe 12, and the positioning protrusions 100 support the wood fire-resistant coating material 20 and the metal plate 28.

The shape, arrangement, and number of the positioning protrusions 100 and positioning holes 102 can be changed as appropriate.

(Action)
Next, the operation of the third embodiment will be described.

As shown in FIG. 12, the wood fire-resistant coating material 20 provides fire-resistant coating to the outer surface 12A of the steel pipe 12 of the CFT column 10 via a metal plate 28 as an insulating layer. As a result, if, for example, combustion continues partially on the outer surface 20A of the wood fire-resistant coating material 20 during a fire, the metal plate 28 diffuses the fire heat, dispersing and transmitting the fire heat to the entire steel pipe 12. As a result, localized temperature increases in the steel pipe 12 are suppressed. This improves the fire resistance of the CFT column 10.

As shown in Figures 12 and 13, the wood fire-resistant covering material 20 and the metal plate 28 are removably attached to the outer surface 12A of the steel pipe 12 via a pair of snap fits 90. This allows the wood fire-resistant covering material 20 and the metal plate 28 to be easily attached to the outer surface 12A of the steel pipe 12. In addition, the wood fire-resistant covering material 20 and the metal plate 28 can be easily replaced or dismantled.

Furthermore, by inserting the positioning protrusions 100 protruding from the outer surface 12A of the steel pipe 12 into the positioning holes 102 formed in the wood fire-resistant covering material 20 and the metal plate 28, it is possible to suppress the positional deviation in the vertical width direction of the wood fire-resistant covering material 20 and the metal plate 28 relative to the outer surface 12A of the steel pipe 12, and to more reliably support the wood fire-resistant covering material 20 and the metal plate 28.

(Modification of the third embodiment)
Next, a modification of the third embodiment will be described.

In the modified example shown in FIG. 14, a pair of snap fits 110 are provided on the outer surface 12A of the steel pipe 12 with a gap between them in the material axis direction of the steel pipe 12. The claw pieces 110A of each snap fit 110 are elastically deformable in the material axis direction of the steel pipe 12.

Each claw 110A is formed on the wood fire-resistant coating material 20 and engages with an engaged surface 112 facing the outer surface 20A of the wood fire-resistant coating material 20. This allows the wood fire-resistant coating material 20 and the metal plate 28 to be detachably attached to the outer surface 12A of the steel pipe 12 via a pair of snap fits 110. The claw 110A is an example of an engaging portion, and the engaged surface 112 is an example of an engaged portion.

In addition, a pin-shaped positioning protrusion 120 is provided on the outer surface 12A of the steel pipe 12. By inserting (fitting) this positioning protrusion 120 into a positioning hole 122 formed in the wood fireproof covering material 20 and the metal plate 28, the positional deviation of the wood fireproof covering material 20 and the metal plate 28 in the width direction and the length direction (up and down direction) relative to the outer surface 12A of the steel pipe 12 is suppressed, and the wood fireproof covering material 20 and the metal plate 28 are supported by the positioning protrusion 120.

In this way, the outer surface 12A of the steel pipe 12 may be provided with a pair of snap fits 110 spaced apart in the material axis direction of the steel pipe 12. Also, the outer surface 12A of the steel pipe 12 may be provided with both a pair of snap fits 110 spaced apart in the material axis direction of the steel pipe 12, and a pair of snap fits 90 (see FIG. 12) spaced apart in the width direction of the steel pipe 12.

(Fourth embodiment)
Next, a fourth embodiment will be described. In the fourth embodiment, the same reference numerals will be used to designate the same components as those in the first to third embodiments, and the description thereof will be omitted as appropriate.

As shown in FIG. 15, in the fourth embodiment of the fire-resistant coating structure for a concrete-filled steel pipe, a wood-based fire-resistant coating material 140 is attached to the outer circumferential surface 132A of a circular steel pipe 132 via a gap 144 as an insulating layer.

Specifically, the CFT column 130 comprises a round steel pipe 132 and concrete 134 filled inside the round steel pipe 132. The wood fire-resistant coating material 140 is formed in an overall cylindrical shape so as to surround the round steel pipe 132. This wood fire-resistant coating material 140 has multiple divided pieces 142 that are divided in the circumferential direction.

The split piece 142 is formed in a trapezoidal shape when viewed from the axial direction of the wood fire-resistant coating material 140. The inner surface of this split piece 142 is curved convexly toward the round steel pipe 132 and is in line contact with the outer circumferential surface 132A of the round steel pipe 132. This forms a gap 144 as an insulating layer between the outer circumferential surface 132A of the round steel pipe 132 and the inner circumferential surface 140B of the wood fire-resistant coating material 140 (split piece 142). In other words, the wood fire-resistant coating material 140 provides fire-resistant coating to the outer circumferential surface 132A of the round steel pipe 132 through the gap 144.

The split piece 142 is removably attached to the round steel pipe 132 by a screw member 150 and a nut 152 that protrude from the outer circumferential surface 132A of the round steel pipe 132. The screw member 150 is, for example, a stud bolt, and one end of the screw member 150 is butted against the outer circumferential surface 132A of the round steel pipe 132 and joined by welding or the like. The screw member 150 is inserted into a circular mounting hole 146 formed on the inner circumferential surface (inner surface) 140B of the wood fire-resistant coating material 140 (split piece 142).

A circular countersunk 148 is formed on the outer peripheral surface (outer surface) 140A of the wood fire-resistant coating material 140 (split piece 142) leading to the mounting hole 146. The diameter of the countersunk 148 is made larger than the diameter of the mounting hole 146. A nut 152 is housed in the countersunk 148. By tightening the nut 152 into the screw member 150, the wood fire-resistant coating material 140 is removably attached to the outer peripheral surface 132A of the round steel pipe 132.

A wooden plug 149 that covers and conceals the nut 152 is fitted into the countersink 148. This wooden plug 149 insulates the screw member 150 and the nut 152 and enhances the design of the outer surface 140A of the wood fire-resistant coating material 140.

(Action)
Next, the operation of the fourth embodiment will be described.

The wood fire-resistant coating material 140 provides fire-resistant coating to the outer peripheral surface 132A of the round steel pipe 132 through a gap 144. This gap 144 forms an insulating layer (air layer) between the outer peripheral surface 132A of the round steel pipe 132 and the inner peripheral surface 140B of the wood fire-resistant coating material 140, thereby improving the fire resistance of the CFT column 130.

In addition, by dividing the cylindrical wood fire-resistant coating material 140 into multiple split pieces 142 in the circumferential direction, the transportability and installation of the split pieces 142 are improved.

Furthermore, by attaching the split piece 142 to the outer circumferential surface 132A of the round steel pipe 132 using the screw member 150 and nut 152, the split piece 142 can be easily replaced or disassembled.

(Modification of the fourth embodiment)
Next, a modification of the fourth embodiment will be described.

In the modified example shown in FIG. 16, the split piece 142 is removably attached to the outer circumferential surface 132A of the round steel pipe 132 via a pair of snap fits 160. Each snap fit 160 has a claw 160A that can elastically deform in the circumferential direction of the round steel pipe 132. This claw 160A is formed on the end surface of the split piece 142 and engages with an engaged surface 162 that faces the outer circumferential surface 140A of the wood fire-resistant coating material 140. The claw 160A is an example of an engaging portion, and the engaged surface 162 is an example of an engaged portion.

A positioning protrusion 170 is provided on the outer circumferential surface 132A of the round steel pipe 132. This positioning protrusion 170 is inserted (fitted) into a positioning hole 172 formed in the split piece 142.

In this way, the split piece 142 may be removably attached to the round steel pipe 132 using a pair of snap fits 160.

Next, in the modified example shown in FIG. 17, the outer peripheral surface (outer surface) 180A of the cylindrical wood fire-resistant covering material 180 is cut into a circular cross-section. This improves the design of the wood fire-resistant covering material 180. A gap 144 is formed between the inner peripheral surface (inner surface) 180B of the wood fire-resistant covering material 180 and the outer peripheral surface 132A of the round steel pipe 132.

(Manufacturing method of wood fire-resistant coating material)
Here, an example of a method for manufacturing the wood fire-resistant coating material 180 will be described.

(Cutting process)
First, the cutting process will be described. As shown in Fig. 18, the wood fire-resistant coating material 180 has a plurality of divided pieces 182 divided in the circumferential direction. In the cutting process, the plurality of divided pieces 182 to be cut are detachably attached to the outer circumferential surface 190A of the rotating shaft body 190.

As an example, the rotating shaft body 190 is formed in a cylindrical shape. Note that the rotating shaft body 190 is not limited to a cylindrical shape, and may be a columnar shape.

The outer surface 182A of the split piece 182 is flat. The split piece 182 is detachably attached to the outer circumferential surface 190A of the rotating shaft body 190 by a screw member 150 and a nut 152 that protrude from the outer circumferential surface 190A of the rotating shaft body 190.

In this state, the rotating shaft body 190 is rotated around the central axis O by a rotating device (not shown), while a cutting blade 192 is brought into contact with the outer surface 182A of the split piece 182 (wood fire-resistant covering material 180), cutting the outer peripheral surface 180A (see FIG. 17) of the wood fire-resistant covering material 180. This makes it easy to process the outer peripheral surface 180A of the wood fire-resistant covering material 180 into a circular cross-section.

(Installation process)
Next, the attachment process will be described. In the attachment process, the split pieces 182 are removed from the rotating shaft body 190. Then, the removed split pieces 182 are attached to the round steel pipes 132.

Specifically, the split piece 182 is attached to the round steel pipe 132 by a screw member 150 and a nut 152 that protrude from the outer circumferential surface 132A of the round steel pipe 132. This forms a cylindrical wood fire-resistant coating material 140 that surrounds the round steel pipe 132. This wood fire-resistant coating material 140 provides fire-resistant coating to the outer circumferential surface 132A of the round steel pipe 132 via a gap 144 that serves as an insulating layer. This makes it possible to improve the design of the CFT column 130 while also improving its fire resistance.

(Modifications of the first to fourth embodiments)
Next, modifications of the first to fourth embodiments will be described.

The fire-resistant coating structure for the concrete-filled steel pipe according to the first to fourth embodiments can be applied not only to columns but also to structural members such as beams.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and one embodiment and various modified examples may be used in appropriate combination, and the present invention may of course be embodied in various forms without departing from the spirit of the present invention.

10 Concrete-filled steel pipe column 12 Steel pipe 12A Outer surface (outer surface of steel pipe)
14 Concrete 20 Wood fireproof coating material 22 Gap (insulation layer)
28 Metal plate (insulating layer)
30 Screw member 40 Heat insulating material (heat insulating layer)
62 Insulation material (insulation layer)
70 Positioning protrusion 72 Positioning hole 90A Claw (engagement portion)
94L Engaged surface (engaged part)
100 Positioning protrusion 102 Positioning hole 110A Claw (engagement portion)
112 Engaged surface (engaged part)
120 Positioning protrusion 122 Positioning hole 130 Concrete-filled steel pipe column 132 Round steel pipe 132A Outer periphery (outer periphery of round steel pipe)
134 Concrete 140 Wood fireproof coating material 140A Outer surface 140B Inner surface 142 Divided piece 144 Gap (insulating layer)
150 Screw member 160A Claw piece (engagement portion)
162 Engaged surface (engaged part)
170 Positioning protrusion 172 Positioning hole 180 Wood fireproof covering material 180A Outer periphery (Outer periphery of wood fireproof covering material)
182 Split piece 190 Rotating shaft body 190A Outer circumferential surface (Outer circumferential surface of the rotating shaft body)

Claims (5)

A steel pipe filled with concrete;
A plurality of wood fire-resistant covering materials surrounding the steel pipe;
A plurality of metal plates are attached to the entire inner surfaces of the plurality of wood fire-resistant covering materials, respectively , and are integrated with the plurality of wood fire-resistant covering materials in advance, and surround the outer surface of the steel pipe in an annular shape via gaps to provide fire-resistant covering;
A fire-resistant coating structure of a concrete-filled steel pipe. A wood fireproof coating material is attached to a steel pipe filled with concrete and provides fireproof coating to an outer surface of the steel pipe via a heat insulating layer;
A screw member protruding from the outer surface of the steel pipe;
Equipped with
The wood fire-resistant coating material is attached to the steel pipe using the screw member with a gap between the outer surface of the steel pipe and the wood fire-resistant coating material as the insulating layer.
Fire-resistant coated concrete-filled steel pipe structure. A wood fireproof coating material is attached to a steel pipe filled with concrete and provides fireproof coating to an outer surface of the steel pipe via a heat insulating layer;
An engaged portion provided on the wood fire-resistant covering material and facing an outer surface side of the wood fire-resistant covering material;
An engaging portion provided on an outer surface of the steel pipe and engaged with the engaged portion;
A fire-resistant coating structure of a concrete-filled steel pipe. A wood fireproof coating material is attached to a steel pipe filled with concrete and provides fireproof coating to an outer surface of the steel pipe via a heat insulating layer;
A positioning protrusion protruding from the outer surface of the steel pipe and inserted into a positioning hole formed on the inner surface of the wood fire-resistant covering material;
A fire-resistant coating structure of a concrete-filled steel pipe. A method for manufacturing a cylindrical wood fireproof coating material, which is attached to a round steel pipe filled with concrete and fireproofs the outer peripheral surface of the round steel pipe through a heat insulating layer,
a cutting process for cutting the outer peripheral surface of the wood fire-resistant coating material into a circular cross-sectional shape while rotating a rotating shaft having a plurality of divided pieces formed by dividing the wood fire-resistant coating material in the circumferential direction and attached to the outer peripheral surface of the rotating shaft;
a mounting step of removing the split pieces from the rotating shaft body and mounting the split pieces to the round steel pipe;
A method for manufacturing a wood fire-resistant coating material comprising the steps of: