JP3308664B2 - Centrifugally formed steel tube concrete column and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugally formed steel pipe concrete column suitably used for buildings and civil engineering structures, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, there has been provided a centrifugally formed steel pipe concrete column in which a steel pipe is filled with concrete, the steel pipe is rotated at high speed around its axis, and the filled concrete is centrifugally formed. Since such concrete columns are compacted by a simple centrifugal molding operation to increase the strength of the filled concrete, reinforcing steel is buried in the hardened concrete body, or the hardened concrete body is inserted through steel wires or steel rods. Therefore, there is an advantage that the proof stress of the concrete hardened body can be easily and economically increased without giving a prestress.

[0003]

However, in the case of the centrifugally molded steel pipe concrete column, since the concrete body is centrifugally molded, the hardened concrete body has a hollow portion in the center thereof. for that reason,
It is considered that the steel pipe does not sufficiently exert a restraining effect on the hardened concrete body, and particularly when a large axial compressive force is applied, internal collapse of the hardened concrete body into the cavity may occur. Due to such a fear, the centrifugally formed steel pipe concrete column is usually used by filling a mortar into a hollow portion of the concrete column at the time of constructing a building structure and then hardening the mortar. However, filling the mortar at the time of construction in this way creates a new problem that the hardened concrete is formed by centrifugal molding in the steel pipe and the meaning of precasting is lost, and there is no merit in cost. Has occurred.

[0004] The present inventors also consider increasing the strength of, for example, the hardened concrete itself and the resistance to internal collapse in order to eliminate the filling of mortar into the cavity. As one method for increasing the strength of such a concrete hardened body, various reinforcing fibers are added to ready-mixed concrete and uniformly dispersed, and the reinforcing fibers are uniformly dispersed in the resulting hardened concrete. There is a method of increasing the strength by dispersing. However, by uniformly dispersing the reinforcing fibers in the hardened concrete in this way, although the strength of the hardened concrete itself increases as a whole, in terms of resistance to internal collapse, that is, in the steel pipe side, The strength of the cured body on the cavity side with respect to the cured body is still relatively low.Therefore, considering the cost increase due to the addition of the reinforcing fiber, an effective method suitable for implementation is considered. It must not be.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to eliminate the need to fill a mortar into a hollow portion of a building or a civil engineering structure at the time of construction and to apply an axial compressive force. In particular, it is an object of the present invention to provide a centrifugally formed steel pipe concrete column having a sufficient resistance to internal collapse and a method for producing the same.

[0006]

Means for Solving the Problems Claim 1 of the present invention
In the centrifugally molded steel pipe concrete column described above, a centrifugally molded steel pipe obtained by having a centrifugally molded concrete hardened body inside a steel pipe and leaving an axial cavity of the steel pipe formed at the time of centrifugally molding the hardened concrete body In the concrete column, near the hollow portion in the hardened concrete body, a mesh bar is arranged in a cylindrical shape along the axial direction of the steel pipe, and reinforcing fibers are provided in the hardened concrete body on the hollow portion side of the mesh bar. The scattered portion is a means for solving the above problem. In the method for manufacturing a centrifugally formed steel pipe concrete column according to claim 2, concrete is filled into the inside of the steel pipe, and the steel pipe is rotated at high speed around its axis to centrifugally mold the filled concrete to manufacture a centrifugally formed steel pipe concrete column. In doing so, the reinforcing fiber is added in advance to the concrete to be filled, and prior to filling the concrete, mesh bars are arranged in a cylindrical shape at the center of the steel pipe along the axial direction of the steel pipe, Then, the above-mentioned concrete is filled and supplied into the inside of the cylindrical mesh reinforcement so that the mesh reinforcement is buried in the hardened concrete body, and the centrifugal molding is performed.

[0007]

According to the centrifugally formed steel pipe concrete column according to the first aspect of the present invention, a mesh reinforcement is arranged in a cylindrical shape along the axial direction of the steel pipe in the vicinity of the cavity in the hardened concrete. Since the reinforcing fibers are scattered in the concrete hardened body on the cavity side, since the vicinity of the hollow portion of the hardened concrete is double reinforced, the resistance to internal collapse is extremely high. Become. According to the method for manufacturing a centrifugally formed steel pipe concrete column according to claim 2, a reinforcing fiber is added in advance to the concrete to be filled in the steel pipe, and before the concrete is filled, the reinforcing fiber is added along the axial direction of the steel pipe. A mesh bar is arranged in the center of the steel pipe in a cylindrical shape, and then the concrete is filled and supplied to the inside of the cylindrical mesh bar so that the mesh bar after molding is embedded in the concrete hardened body. Since the centrifugal molding is performed, the obtained centrifugally molded steel pipe concrete has mesh reinforcing bars arranged on the cavity side of the hardened concrete body, and the reinforcing fibers added to the concrete are meshed at the time of centrifugal molding. Since the movement to the steel pipe side is hindered by the streaks, much remains inside the mesh streaks. Therefore, the obtained centrifugally formed steel pipe concrete has an increased resistance to internal collapse.

[0008]

Hereinafter, the present invention will be described in detail. FIG. 1 is a view showing one embodiment of a centrifugally formed steel pipe concrete column according to the first aspect of the present invention. In this figure, reference numeral 20 denotes a centrifugally formed steel pipe concrete column (hereinafter, abbreviated as a concrete column). The concrete column 20 includes a square steel pipe 2, a concrete hardened body 21 provided inside the steel pipe 2, and a fireproof coating material 4 coated on the outer peripheral surface of the steel pipe 2.
It consists of:

[0009] The hardened concrete body 21 is adhered and hardened on the inner surface of the steel pipe 2 by centrifugal molding, and a hollow portion 23 formed at the time of centrifugal molding is left in a central portion (near the axis of the steel pipe 2). It was formed. Further, in the vicinity of the hollow portion 23 in the hardened concrete body 21, a mesh bar 22 shown in FIG. And the reinforcing fibers 6 are scattered so as to be sparse on the steel pipe 2 side. The fire-resistant coating material 4 is made of a lightweight and excellent fire-resistant material such as a gypsum board, various chemical boards, mats, and a spraying material. After the concrete hardened body 21 is subjected to centrifugal molding, it is used in a factory or a construction site. It is attached or sprayed on the outer peripheral surface of the steel pipe 2 by bonding or the like.

As shown in FIG. 2, the mesh streaks 22 are formed by forming a wire mesh in a cylindrical shape so that the wires are arranged in an oblique direction. The diameter of the mesh is preferably smaller than the fiber length of the reinforcing fibers 6.

The reinforcing fibers 6 are appropriately selected from steel fiber, vinylon fiber, carbon fiber, glass fiber, aramid fiber, various ceramic fibers and the like according to the required degree of reinforcement of the hardened concrete 21 and used. . The fiber length and fiber diameter of the reinforcing fibers 6 are also appropriately determined according to the type of the selected fiber and the required degree of reinforcement. The fire-resistant coating material 4 is made of a lightweight and excellent fire-resistant material such as a gypsum board, various chemical boards, mats, and a spraying material. After the concrete hardened body 21 is subjected to centrifugal molding, it is used in a factory or a construction site. It is attached or sprayed on the outer peripheral surface of the steel pipe 2 by bonding or the like.

In order to manufacture such a concrete column 20, a conventionally well-known centrifugal molding method can be adopted.
That is, the steel pipe 2 is inserted through a cylindrical (cylindrical) rotating body having an appropriate through-hole for extrapolating the steel pipe 2, and after the concrete before hardening is filled in the steel pipe 2, the rotating body is removed. A method of performing centrifugal molding by supporting a roller of a known centrifugal molding machine and rotating the roller at a high speed, or performing centrifugal molding by fixing both ends of a steel pipe 2 to a rotating body and rotating the rotating body at a high speed. The method is adopted.

At this time, the mesh streaks 22 are previously placed in the steel pipe 2.
At the center of the steel pipe 2 so that the central axis of the mesh streaks 22 substantially coincides with the axis of the steel pipe 2, and is fixed at that position with an appropriate jig (not shown).
The size of the mesh streaks 22 (diameter in plan view)
The amount of concrete to be introduced is determined in advance by experiments or calculations so that when the concrete is compacted by centrifugal molding and hardened, the mesh streaks 22 are located in the vicinity of the cavity 23 to be formed.

Next, concrete to which a predetermined amount of reinforcing fibers 6 have been added in advance is introduced into the mesh streaks 22, and centrifugal molding is performed. Then, reinforcing fiber 6 ...
Since the movement toward the steel pipe 2 is hindered by the mesh streaks 22, the streaks remain largely inside the mesh streaks 22, and are densely scattered in the vicinity of the cavity 23 as a result.

[0015] Here, when concrete containing a relatively light fiber such as vinylon fiber or glass fiber is added as the reinforcing fibers 6 by centrifugal molding, the reinforcing fibers 6 in the concrete become cement particles forming the concrete. Due to the difference in density and fluidity with gypsum particles, fine aggregate, coarse aggregate, water, etc., they gather inside without moving to the steel pipe side, and the dewatering from the concrete proceeds by centrifugal molding and the concrete hardens I do. Therefore, regardless of the fineness of the mesh streaks 22, as shown in FIG. 1, the mesh streaks are densely scattered around (near) the hollow portion 23 formed by centrifugal molding and sparsely scattered on the steel pipe 2 side. Become.

When a fiber having a relatively high density such as a steel fiber is added, concrete without the fiber and concrete with the added fiber are prepared. Then, concrete not added is first introduced into the steel pipe 2 and centrifugally molded. After dehydration from the concrete has sufficiently proceeded, concrete with newly added fiber is introduced into the concrete after centrifugal molding in the steel pipe 2. And centrifuge again. Then, a hardened concrete without fiber is formed on the inner peripheral surface side of the steel pipe 2 by the above-mentioned centrifugal molding, and further inside (the cavity portion 23 side).
A cured body in which fibers are scattered is formed. Therefore, in the concrete hardened body obtained in this way,
The reinforcing fibers 6 are densely scattered around (near) the hollow portion 23, and zero (or almost zero) on the steel pipe 2 side.
It becomes.

After the centrifugal molding is completed, the concrete column 20 is obtained by sticking or spraying the refractory coating 4 on the outer peripheral surface of the steel pipe 2.

In such a concrete column 20, a mesh bar 22 is provided in the vicinity of the hollow portion 23 in the hardened concrete body 21 to thereby replenish the hollow portion 23 side. 21 is more resistant to internal collapse. Also, the mesh streaks 22
Since the wires are formed in a cylindrical shape so that the wires are arranged in the oblique direction, the wires are also arranged in the oblique direction even in the concrete hardened body 21, whereby the shearing of the concrete column 20 is performed. Increased resistance to force.

At the same time, the reinforcing fibers 6 are densely scattered and reinforced on the side of the hollow portion 23 in the hardened concrete body 21, so that the side of the hollow portion 23 is double reinforced, thereby hardening the concrete. The resistance to the internal collapse of the body 21 becomes extremely high. Therefore, when this concrete column is used as a structure, there is no need to fill the cavity 23 with mortar at the construction site.

It is to be noted that the mesh streaks are not necessarily those in which the wires are obliquely formed in a cylindrical shape with a lower body, but may be those in which the wires are arranged vertically and horizontally.

In the above-described embodiment, a square steel pipe is used as the steel pipe 2, but the present invention is not limited to this.
Various shapes such as a circle, a triangle, a pentagon or more, and an ellipse can be used. Further, if necessary, various kinds of streaks may be used as a jig for fixing the mesh streaks 22 to the steel pipe 2 at the time of centrifugal molding, so that the concrete columns 20 can be further strengthened.
Further, in the above-described embodiment, the fire-resistant coating material 4 is adhered or sprayed to the steel pipe 2 in a factory or the like, and this is used as a concrete column. However, the fire-resistant coating material may be post-applied or sprayed at the construction site, Therefore, the concrete column of the present invention may be formed of the steel pipe 2 and the concrete hardened body formed therein.

[0022]

As described above, in the centrifugally formed steel pipe concrete column according to the first aspect of the present invention, mesh bars are arranged in the vicinity of the hollow portion in the hardened concrete body, and reinforcement is provided on the hollow side of the mesh bar. Since the fibers are interspersed, the vicinity of the hollow portion of the hardened concrete body is double reinforced, so that the resistance to internal collapse becomes extremely high. In the method for manufacturing a centrifugally formed concrete column according to the second aspect, a mesh bar is arranged in a cylindrical shape at a central portion of a steel pipe, and then the mesh bar after molding is embedded inside the hardened concrete body inside the mesh bar. Centrifugal molding is performed by filling and supplying concrete with reinforcing fiber added to it, so the obtained centrifugally molded steel pipe concrete is provided with mesh bars on the hollow side of the concrete hardened body, and moreover, in the concrete A large amount of the added reinforcing fiber stays inside the mesh streaks. Therefore, the obtained centrifugally formed steel pipe concrete has a high resistance to internal collapse due to the reinforcing effect of the mesh streaks and the reinforcing fibers.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a centrifugally formed steel pipe concrete column according to claim 1.

FIG. 2 is a perspective view of a mesh streak.

[Explanation of symbols]

 Reference Signs List 20 Centrifugally formed steel pipe concrete column 2 Steel pipe 21 Concrete hardened body 22 Mesh bar 23 Cavity 6 Reinforcing fiber

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Terutake Imamura 2-10-26 Fujimi, Chiyoda-ku, Tokyo Inside Maeda Construction Industries Co., Ltd. (72) Inventor Satoshi Miyaki 2-26-10 Fujimi, Chiyoda-ku, Tokyo Maeda (56) References JP-A-4-312657 (JP, A) JP-A-62-294512 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E04C 3 / 34

Claims (2)

(57) [Claims] 1. A centrifugally formed steel pipe concrete column having a hardened centrifugally formed concrete body inside a steel pipe and leaving a hollow portion in the axial direction of the steel pipe formed in the hardened concrete body during centrifugal molding. In the vicinity of the cavity in the hardened concrete body, mesh reinforcing bars are disposed in a cylindrical shape along the axial direction of the steel pipe, and reinforcing fibers are scattered in the hardened concrete body on the hollow side of the mesh reinforcing bar. A centrifugally formed steel pipe concrete column characterized by being hampered. 2. Concrete is filled in a steel pipe, and the steel pipe is rotated at a high speed around its axis to form the filled concrete by centrifugal molding. And before filling the concrete,
A mesh streak is arranged in a cylindrical shape at the center of the steel tube along the axial direction of the steel tube, and then, after the molding, the mesh streak is embedded inside the hardened concrete body inside the cylindrical mesh streak. A method for producing a centrifugally molded steel pipe concrete column, characterized in that concrete is charged and supplied to perform centrifugal molding.