JPH04120340A - Concrete pillar and its forming process with centrifugal force - Google Patents

Abstract

PURPOSE:To increase the twisting strength by inserting a perforated cylinder of iron plate in a cylindrical form, pouring in concrete, rotating the form round its axis, and forming a cylindrical body due to centrifugal force. CONSTITUTION:A punching metal 5 is formed by providing a steel plate with a number of long holes 4 at a constant pitch for passage of aggregate, and is bent cylindrically with the long diameter of long hole 4 directed axially, and the two end faces of the metal 5 are butted together and welded. Thus a perforated cylinder 3 of iron plate is formed. This cylinder 3 is inserted concentrically in a form made in a cylindrical shape, and inside of the cylinder 3 a plurality of tensioning rods 2 for application of prestress are inserted axially at a constant pitch and tensioned and their ends are fixed to the form. Concrete is poured in the form, which is then rotated, and a cylindrical body 1 is formed due to centrifugal force. Thereby the amount of deflection can be reduced and the twisting strength be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a concrete columnar body and a centrifugal force forming method thereof.

<Prior art> Concrete columnar bodies used as concrete poles and concrete piles are made by organizing main axial reinforcing bars and spiral or ring reinforcing bars of circumferential reinforcing bars into a centrifugally formed concrete cylindrical body. Reinforced cages assembled into shapes are buried.

In the case of centrifugally forming the concrete columnar body, first, the main reinforcement of the axial reinforcement and the spiral or ring reinforcement of the circumferential reinforcement are assembled into a cylindrical shape to form a reinforcing bar cage.

Next, the above-mentioned reinforcing cage is inserted into the cylindrical formwork, and concrete is poured into it.

The cylindrical formwork rotates around its central axis, and the concrete within the formwork is centrifugally formed into a cylindrical body in which a reinforcing bar cage is embedded within the formwork.

Thereafter, the concrete cylindrical body within the formwork is cured and hardened, and then demolded to obtain a concrete columnar body in which a reinforcing bar cage is embedded.

<Problems to be Solved by the Invention> However, the concrete columnar bodies described above are designed with only bending strength in mind, and have a large amount of deflection and do not have sufficient torsional strength.

In order to reduce the amount of deflection and improve the torsional strength of the above concrete columnar body, increase the bonding strength at the intersection of the axial and circumferential reinforcing bars of the reinforcing bar cage, and It is possible to increase the number and thickness.

However, in order to increase the bond strength at the intersection of the axial and circumferential reinforcing bars of the reinforcing bar cage, the axial and circumferential reinforcing bars are bars or wires with a circular cross section, and the intersection of the axial and circumferential reinforcing bars is There is a limit due to the small contact area.

In addition, increasing the number of axial reinforcing bars and circumferential reinforcing bars in a reinforcing bar cage reduces the mesh size for passing concrete aggregate formed by the axial reinforcing bars and circumferential reinforcing bars, and also increases the number of axial reinforcing bars and circumferential reinforcing bars. There is a limit to this because it greatly increases the amount of time and effort required.

In addition, increasing the thickness of the axial reinforcing bars and circumferential reinforcing bars of the reinforcing bar cage means that the thickness of the part where the axial reinforcing bars and the circumferential reinforcing bars intersect and overlap increases significantly, and the concrete cover thickness increases. There is a limit to the point where it decreases significantly.

In the end, conventional concrete columnar bodies use reinforcing bar cages assembled by organizing the main axial reinforcing bars and the spiral or ring bars of the circumferential reinforcing bars, which reduces the amount of deflection and improves torsional strength. is difficult.

An object of the present invention is to solve the conventional problems as described above.

Means for Solving the Problems> The present inventor has proposed that a perforated steel plate tube, which is formed by curving a steel plate with a large number of holes such as punched metal or expanded metal into a cylindrical shape, can be used for axial reinforcing bars in a reinforcing bar layer. Noting that it is equivalent to an integrated circumferential reinforcing bar and is strong against bending and torsion, they came up with the idea of burying a Komei iron plate tube in a concrete column.

That is, the present invention provides that a cylindrical steel plate tube formed by curving a steel plate with a large number of holes through which concrete aggregate passes is embedded in a centrifugally formed concrete tube. It is a concrete columnar body characterized by

In addition, the present invention involves curving an iron plate with a large number of holes through which concrete aggregate passes into a cylindrical shape to form a cylindrical iron plate cylinder, inserting the cylindrical iron plate cylinder into the cylindrical formwork, Pour concrete.

A cylindrical formwork is rotated around its central axis, and the concrete inside the formwork is centrifugally formed into a cylindrical body by burying a Komei iron plate cylinder within the formwork, and concrete with a Komei iron plate cylinder buried. This is a centrifugal force forming method for concrete columnar bodies, which is characterized by obtaining columnar bodies.

Effect> In the present invention, the perforated steel plate tube embedded in the concrete column corresponds to an integrated axial reinforcing bar and circumferential reinforcing bar of a reinforcing bar cage, and is strong against bending and torsion.

In addition, a steel plate tube is made by curving a steel plate with many holes, such as punched metal or expanded metal, into a cylindrical shape, and is compared to a reinforcing bar cage, which is assembled by organizing axial reinforcing bars and circumferential reinforcing bars. Therefore, it is easy to manufacture.

In addition, the perforated iron plate tube can easily increase the strength against bending and torsion by increasing the thickness of the iron plate curved into a cylindrical shape and having a large number of holes.

<Effects of the Invention> Since the concrete columnar body of the present invention embeds a perforated iron plate tube as described above, it is possible to reduce the amount of deflection and improve torsional strength compared to conventional products in which a reinforcing bar cage is embedded. It's easy.

<Example> As shown in Figs. 1 and 2, the concrete columnar body of this example is a cylindrical concrete cylinder l formed by centrifugal force.
A plurality of prestressing tension rods 2 are buried in the axial direction at equal intervals, and a cylindrical perforated iron plate tube 3 is concentrically buried outside the tension rods 2.

As shown in FIG. 3, the perforated iron plate cylinder 3 is made of a punched metal 5 in which a large number of long holes 4 are formed through a steel plate at equal intervals.
The elongated hole 4 is curved into a cylindrical shape with the long diameter direction being the axial direction, and the end surfaces on both sides of the punched metal 5 are butted and welded.

The long hole 4 of the punching metal 5 has a long axis of 321 cm, a short axis of 16 layers, and a pitch of 32+ in the long axis direction.
5 mm, and the pitch in the minor axis direction is 16+5 cm. Note that the punching metal 5 has a thickness of three layers.

The maximum aggregate size in the concrete forming the concrete cylinder l is 15 mm.

Incidentally, during centrifugal force forming, the concrete aggregate passes through the long holes 4 of the steel plate tube 3 and is dispersed inside and outside the steel plate tube 3.

The concrete columnar body of this example is more resistant to bending and torsion than conventional products with embedded reinforcing bar cages. That is, the bending strength is high and the amount of deflection is small, and the torsional strength is high and the amount of twisting is small.

When centrifugally forming the concrete columnar body of this example, the above-mentioned Komei iron plate tube 3 is inserted concentrically into the cylindrical formwork, and multiple prestressing tubes are inserted into the inner position of the Komei iron plate tube 3. The tension rods 2 are inserted in the axial direction at equal intervals. Each tension bar 2 is tensioned to secure its end to the formwork.

Concrete with a maximum aggregate size of 15 layers is injected into the steel plate tube 3 in the formwork.

The formwork rotates around its central axis, and the concrete in the formwork is centrifugally formed into a cylindrical body l in which each tension rod 2 and perforated iron plate cylinder 3 are embedded in the formwork.

After that, the concrete cylindrical body l in the formwork is cured and hardened, and the tension of each tension rod 2 is released and demolded, and each tension rod 2 is removed from the mold.
A concrete columnar body in which the Komei iron plate tube 3 is embedded is obtained.

In this concrete columnar body, the strength against bending and torsion can be easily increased by increasing the thickness of the punched metal 5 forming the perforated iron plate tube 3.

(Modifications) ■) A perforated iron plate cylinder is made by bending a punched metal into a cylindrical shape, through which a large number of circular holes are inserted at equal intervals, and then fixing the punched metal by abutting both end faces of the punched metal.

2) Komei iron plate tube is made of steel expanded metal (JIS G 3351) with many diamond-shaped holes penetrated at evenly spaced positions.
Curve into a cylindrical shape and secure the ends of the extended band metal on both sides.

3) , :l711J-Nfif-shaped body is made of fiber-reinforced concrete mixed with steel fibers and other reinforcing fibers.

[Brief explanation of the drawing]

FIG. 1 is a partial front view of a concrete columnar body according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the concrete columnar body. FIG. 3 is a partial front view of the perforated metal of the perforated iron plate tube of the concrete columnar body. ■ = Concrete cylindrical body 3: Perforated iron plate tube 4: Long hole 5: Punched metal perforated iron plate

Claims (1)

[Claims] 1. A cylindrical iron plate tube, which is formed by curving a steel plate with numerous holes through which concrete aggregate passes, is embedded in a centrifugally formed concrete tube. A concrete columnar body characterized by: 2. A steel plate with many holes through which the concrete aggregate passes is curved into a cylindrical shape to form a cylindrical iron plate cylinder, the cylindrical iron plate cylinder is inserted into the cylindrical formwork, and concrete is poured into it. By rotating the cylindrical formwork around its central axis, the concrete inside the formwork is centrifugally formed into a cylindrical body with a Komei iron plate tube embedded inside the formwork, and a concrete column with a Komei iron plate tube embedded inside the formwork is formed. A centrifugal force forming method for concrete columnar bodies, which is characterized by obtaining a solid body.