JP3308665B2 - Centrifugally formed steel tube concrete column - 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 construction and civil engineering structures.

[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 and the strength of the concrete is strengthened, many concrete bars can be buried in the hardened concrete body, and steel wires and steel rods can be embedded in the hardened concrete body. Without prestressing, that is, the strength of the concrete hardened body can be easily and economically increased.

[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.

[0004] Due to such fears, the centrifugally formed steel tubular concrete columns are usually used by filling the mortar in the hollow portion thereof at the time of building 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. In addition, after centrifugal molding, it is conceivable that the mortar is filled in the cavity at the factory and the precasting is completed, but in that case, the cost advantage is reduced, There is a problem that the weight of the obtained centrifugally formed steel pipe concrete becomes large, which impairs transportability and workability on site.

SUMMARY OF THE INVENTION 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 in a hollow portion of a building or a civil engineering structure when constructing the structure, and to improve transportability and on-site workability. Another object of the present invention is to provide a centrifugally-formed steel pipe concrete column having a sufficient resistance to internal collapse even when an axial compressive force is applied without impairing the structure.

[0006]

The centrifugally formed steel pipe concrete column of the present invention has a hardened centrifugally formed concrete body inside a steel pipe, and the steel pipe formed on the hardened concrete body at the time of centrifugal molding thereof has an axial direction. In a centrifugally formed steel pipe concrete column obtained by leaving a hollow portion, a main reinforcing bar is buried in the hardened concrete along the axial direction of the steel pipe, and an outer hoop reinforcing bar disposed on the steel pipe side, and disposed near the hollow portion. A plurality of reinforcing bars, each of which includes an inner hoop bar and a connecting bar connecting the outer hoop bar and the inner hoop bar, are connected to the main bar and buried in the concrete hardened body. And

[0007]

According to the centrifugally formed steel pipe concrete column of the present invention, the following effects are obtained. When an axial compressive force is applied to the concrete column, the steel pipe side of the hardened concrete works in a direction of expanding outward against the restraining force of the steel pipe, while the hollow side works inward. However, since the inner hoop is located near the cavity, the force against internal collapse near the cavity in the hardened concrete body is increasing, and the outer hoop is swelled outward, which is the joint. Since it is transmitted to the inner hoop streaks via the streaks and acts in a direction opposite to the force of the hardened concrete body near the cavity, the effect on the internal collapse of the concrete body near the cavity is further enhanced.

[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 1 denotes a centrifugally formed steel pipe concrete column (hereinafter abbreviated as a concrete column). The concrete column 1 includes a square steel pipe 2, a concrete hardened body 3 provided inside the steel pipe 2, and a refractory coating material 4 coated on the outer peripheral surface of the steel pipe 2.

[0009] The hardened concrete body 3 is adhered and hardened on the inner surface of the steel pipe 2 by centrifugal molding, and a hollow part 5 formed at the time of centrifugal molding is left in the center part (near the axis of the steel pipe 2). It was formed. The cavity 5 is relatively larger than the cavity formed in the conventional concrete column. In the hardened concrete body 3, main reinforcements 6 are buried at four corners of the steel pipe 2 along the axial direction of the steel pipe 2, respectively. Are connected to each other. Further, an inner hoop muscle 9 is connected to each of the outer hoop muscles 7 via a plurality of (four in the example of FIG. 1) joint muscles 8.

The outer hoop 7 is provided in the form of a ring near the inner surface of the steel pipe 2, and the inner hoop 9 is provided in the form of a ring near the cavity 5 along the outer periphery thereof. Things. The reinforcing bars of the present invention are composed of the outer hoop bars 7, the joint bars 8, and the inner hoop bars 9. 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 3 is centrifugally molded, 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 1, a conventionally 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, steel fiber, glass fiber, vinylon fiber, or the like may be added to the concrete before hardening to be used for reinforcement.

When performing centrifugal molding, prior to this, the main reinforcing bars 6 are connected to the reinforcing bars in advance, and the main reinforcing bars 6 are inserted into the steel pipe 2 so as to be along the axial direction of the steel pipe 2. Insert it. The length (diameter) of the outer hoop bars 7 is set in advance so that the outer hoop bars 7 do not contact the inner wall of the steel pipe 2 after the concrete is hardened. On the other hand, the length (diameter) of the inner hoop muscles 9 is set in advance so as to be located in the vicinity of the hollow portion 5 as described later.
The main reinforcing bars 6 and the reinforcing bars may be attached and fixed in the steel pipe 2 using an appropriate jig, and may be positioned. However, in this example, no special jig or the like is used. Insert it freely inside.

[0013] After the main bars 6 ... and the reinforcing bars are inserted, concrete is introduced into the steel pipe 2 and centrifugal molding is performed. Then, the dewatering from the concrete proceeds by the centrifugal molding, and the outer hoops 7... Particularly located on the steel pipe side are evenly pulled toward the steel pipe 2 by the centrifugal force, whereby the outer hoops 7. Take a balanced position. In addition, about quantity of concrete,
When concrete is compacted by centrifugal molding and hardened, it is determined in advance by experiment or calculation so that the inner hoop streak 7 is located near the cavity 5 to be formed. Also, as described later, in this concrete column 1,
Since the resistance to internal collapse is sufficiently high, the hole diameter of the cavity can be made larger than that of conventional concrete columns, and therefore, the amount of concrete to be injected can be reduced, and the concrete columns thus manufactured Weight and cost can be reduced. Then, after such centrifugal molding is completed, the fireproof coating material 4 is stuck or sprayed on the outer peripheral surface of the steel pipe 2 to obtain the concrete column 1.

In such a concrete column 1,
When an axial compressive force is applied to this, the steel pipe 2 side of the concrete hardened body 3 acts in a direction of expanding outward against the restraining force of the steel pipe 2, while the hollow part 5 acts inward. However, since the inner hoops 9 are arranged in the vicinity of the cavity 5, the vicinity of the cavity 5 in the concrete hardened body 3 has a higher resistance against internal collapse, and the outer hoops 7 ... The expanding force is transmitted to the inner hoops 9 via the joint bars 8 and acts in the opposite direction to the force of the hardened concrete body 3 in the vicinity of the hollow portion 5. The effect on the internal collapse of the body 3 is further enhanced. Therefore, the hollow portion 5 is
Of the concrete column 1 can be made large, thereby making it possible to reduce the weight of the concrete column 1 and the cost associated with the reduction in the amount of concrete.

In the above embodiment, the steel pipe 2 has a square shape, 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. In the above-described embodiment, the connection between the main reinforcements 6 and the reinforcements is performed by the main reinforcements 6 and the outer hoops 7. However, the connection may be performed by the main reinforcements 6 and the inner hoops 9. It is. 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 pillar. However, the fire-resistant coating material may be post-applied or sprayed at a construction site. Therefore steel pipe 2
The concrete pillar according to the present invention may be formed of a concrete hardened body formed inside the concrete pillar.

[0016]

As described above, the centrifugally formed steel pipe concrete column of the present invention has an increased resistance to the internal collapse of the hardened concrete body because the inner hoop streak is disposed near the cavity. When the axial compressive force is applied, the force expanding outward of the outer hoop muscle is transmitted to the inner hoop muscle, and acts in the opposite direction to the force of the hardened concrete body near the cavity. The effect on internal collapse of the body is further enhanced. Therefore, when the concrete column is used as a structure, there is no need to fill the mortar into the cavity at the construction site, which is advantageous in terms of cost and strength. In addition, since the resistance to internal collapse is sufficiently high, it is possible to increase the hole diameter of the cavity compared to the conventional method, which enables the concrete column to be lighter and has improved transportability and on-site construction. Properties can be improved, and the cost can be reduced due to the reduction in the amount of concrete.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a centrifugally formed steel pipe concrete column of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Centrifugal molded steel pipe concrete column 2 Steel pipe 3 Concrete hardened body 5 Cavity part 6 Main bar 7 Outer hoop bar 8 Joint bar 9 Inner hoop bar

──────────────────────────────────────────────────続 き Continuing 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-59-456 (JP, A) JP-B-1-18229 (JP, B2) (58) Fields surveyed ( Int.Cl. ⁷ , DB name) E04C 3/34

Claims (1)

(57) [Claims] 1. A centrifugally formed steel pipe concrete column having a hardened centrifugally formed concrete body inside a steel pipe and leaving an axial cavity of the steel pipe formed at the time of the centrifugally forming the hardened concrete body. A main reinforcement embedded in the concrete hardened body along the axial direction of the steel pipe, and an outer hoop reinforcement disposed on the steel pipe side; an inner hoop reinforcement disposed near the hollow portion; A centrifugally formed steel pipe concrete column, wherein a plurality of reinforcing bars each comprising a connecting bar connecting the inner bar and the inner hoop bar are connected to the main bar and buried in the concrete hardened body.