Manufacturing method for upper column of prefabricated concrete column and upper column of prefabricated concrete column

Abstract

To provide a method for manufacturing an upper column of a prefabricated concrete column, which can manufacture the upper column with a simple configuration without damaging the end of a joint pipe, and to provide an upper column of a prefabricated concrete column. [Solution] The manufacturing method for the upper column of a prefabricated concrete column uses a cylindrical formwork 18, and a joint pipe 6 integrally formed with a seat plate 7 is placed inside the formwork 18 with its protruding portion 13 abutting one end of the formwork 18, and the end of the tensioning member 10 is fixed to the seat plate 7, and concrete is poured into the formwork 18 in a tensioned state on the other end side of the formwork 18, and centrifugally formed so that the concrete portion is integrated with the joint pipe 6.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an upper column of a prefabricated concrete column and to an upper column of a prefabricated concrete column. [Background technology]

[0002] Conventionally, a prefabricated concrete column (fitted joint type concrete column) is constructed by integrating a fitting pipe, which is a fitting joint, into the lower end of the concrete part of one column body, the upper column, and inserting and connecting this fitting pipe into the upper end of the concrete part of the other column body, the lower column.

[0003] When manufacturing the upper column, the end of the tendon is fixed to the seat plate (end plate) connected to the inside of the joint pipe, and the concrete section is cast in a state in which the tendon is tensioned. At this time, a method is known in which the end of the joint pipe is abutted against a step in the formwork to hold the joint pipe within the formwork against the tension force of the tendon (see, for example, Patent Document 1).

[0004] However, this method has the risk of damaging the rust-preventive treatment applied to the end of the joint pipe. Damage to the rust-preventive treatment may cause rust to develop inside the steel pipe, which is difficult to visually inspect, and may cause deterioration that is difficult to detect.

[0005] In this regard, known methods include forming a large seat plate, integrally attaching a joint pipe to the lower part of the seat plate, and abutting the seat plate against the flange at the lower end of the upper formwork of a formwork divided into upper and lower parts to hold the joint pipe within the formwork against the tension of the tendon, and integrally attaching a reinforcing band to the upper part of the seat plate to integrate the concrete part and the seat plate (see, for example, Patent Document 2), and also fixing a tensioning jig to an end plate integrated inside the joint pipe, fixing an anchor plate to the lower part of this tensioning jig, and bringing the anchor plate into contact with the lower end of the formwork to hold the joint pipe within the formwork against the tension of the tendon (see, for example, Patent Documents 2 and 3). While these methods can prevent damage to the joint pipe, they require a large number of parts and large tensioning jigs, etc., and are therefore complex and time-consuming to manufacture. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-112003 [Patent Document 2] Japanese Patent Application Publication No. 2020-147991 [Patent Document 3] Japanese Patent Publication No. 2020-147010 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, there is a need for a method for simply manufacturing an upper column without damaging the end of the joint pipe when applying tension to the tendon.

[0008] The present invention has been made in consideration of these points, and aims to provide a method for manufacturing an upper column of a prefabricated concrete column that can manufacture an upper column with a simple configuration without damaging the end of the joint pipe, and an upper column of a prefabricated concrete column. [Means for solving the problem]

[0009] The method for manufacturing an upper column of a prefabricated concrete column of the present invention is a method for manufacturing an upper column for a prefabricated concrete column, which is provided with a tubular concrete section, a coupling pipe integrally arranged on the outer periphery of one end of the concrete section, a seat plate fixed to the inside of the coupling pipe, and a tension member whose end is fixed to the seat plate and embedded in the concrete section, the coupling pipe having a tubular main body section into one end of which a lower column is inserted, and a protrusion arranged to protrude radially on the outer periphery between both ends of the main body, and the method includes using a cylindrical formwork, placing the coupling pipe with the seat plate integrally formed therewith within the formwork with the protrusion abutting against one end of the formwork, fixing the end of the tension member to the seat plate, pouring concrete into the formwork under tension toward the other end of the formwork, and centrifugal molding is performed to integrate the concrete section with the coupling pipe. [Effects of the Invention]

[0010] According to the present invention, the upper column can be manufactured with a simple structure without damaging the end of the joint pipe. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view showing a manufacturing method for the upper column of the prefabricated concrete column according to the first embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing a portion of a prefabricated concrete column having the same upper column. [Figure 3] FIG. 10 is a perspective view showing an example of a protrusion of a joint pipe of the same upper pillar. [Figure 4] FIG. 10 is a perspective view showing a part of an upper pillar of a prefabricated concrete pillar according to a second embodiment of the present invention. [Figure 5] FIG. 10 is a perspective view showing a part of an upper pillar of a prefabricated concrete pillar according to a third embodiment of the present invention. [Figure 6] FIG. 10 is a perspective view showing an example of a protruding portion of a joint pipe of an upper column of a prefabricated concrete column according to the fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] A first embodiment of the present invention will be described below with reference to the drawings.

[0013] In Figure 2, reference numeral 1 denotes a prefabricated concrete pillar. The prefabricated concrete pillar 1 is used, for example, as a concrete utility pole. The prefabricated concrete pillar 1 comprises an upper pillar 2 and a lower pillar 3, and is assembled so that the upper pillar 2 and the lower pillar 3 are connected vertically.

[0014] The upper column 2 is a centrifugally formed prestressed concrete column integrally comprising a cylindrical concrete portion 5, a cylindrical joint pipe 6 integrated with the outer periphery of the lower end, which is one end of the concrete portion 5, and a seat plate 7, which is an annular end metal fitting, integrated with at least the lower end of the concrete portion 5. The upper column 2 is formed, for example, in a tapered shape with a diameter gradually increasing downward. However, the upper column 2 may be straight, etc., as long as the joint pipe 6 is integrated with the lower end, or may be configured so that only a certain range of the lower end where the joint pipe 6 is integrated is tapered.

[0015] The concrete section 5 is made of prestressed concrete, and has tendons 10 embedded in a series in the axial direction to improve bending strength. The tendons 10 are, for example, PC steel, and a plurality of tendons 10 are arranged circumferentially around the concrete section 5. In this embodiment, the concrete section 5 gradually expands in diameter from the upper end, which is the other end, to the lower end, which is one end. The seat plate 7 integrated with the end face of the concrete section 5 is made of metal and has engaging holes (not shown) through which the ends of the tendons 10 are inserted and fixed.

[0016] The joint pipe 6 is also called a joint steel pipe or the like and is made of metal, for example, steel. The joint pipe 6 integrally comprises a cylindrical main body 12 and a protrusion 13 protruding from the main body 12. In the example shown, the joint pipe 6 is attached approximately halfway between the lower end of the concrete section 5 and the upper end of the lower column 3, but this is not limitative and the proportion on the lower column 3 side may be larger, for example. The surface of the joint pipe 6 is treated with an anti-rust material to prevent rust.

[0017] The main body 12 integrally comprises an integrally formed portion 15 that is integrally formed with the lower end of the concrete portion 5, and an attachment portion 16 that is attached to the upper end of the lower pillar 3. The diameter of the main body 12 gradually increases from the upper end to the lower end at the same or approximately the same gradient as the taper of the concrete portion 5. The outer periphery of the seat plate 7 is integrated with the inner periphery of the main body 12 by welding or the like.

[0018] When the upper column 2 is being formed, the integrally molded portion 15 is placed in advance in a corresponding position within the formwork and is molded integrally with the concrete portion 5. That is, the joint pipe 6 is integrated by integrally molding the integrally molded portion 15 with the lower end side of the concrete portion 5 within the formwork. The integrally molded portion 15, which is integrated with the concrete portion 5, has a tapered outer circumferential surface that is flush or nearly flush with the outer circumferential surface of the concrete portion 5. The seat plate 7 is located below the integrally molded portion 15, and the area of ​​the main body 12 above the top surface of the seat plate 7 forms the integrally molded portion 15.

[0019] The fitting portion 16 is positioned to extend downward relative to the concrete portion 5. In this embodiment, the fitting portion 16 is formed in a tapered shape with the same or approximately the same gradient as the integrally molded portion 15.

[0020] The protrusion 13 is a positioning portion for positioning the joint pipe 6 relative to a formwork for forming the concrete portion 5 of the upper column 2. The protrusion 13 is made of, for example, metal, is integrated with the outer peripheral surface of the main body portion 12 by welding or the like, and protrudes radially from the outer peripheral surface of the main body portion 12. The protrusion 13 is located between both ends of the main body portion 12. That is, the protrusion 13 is located in a range below the upper end of the main body portion 12 and above the lower end of the main body portion 12. The vertical position of the protrusion 13 on the main body portion 12 may be any position between both ends of the main body portion 12, but in this embodiment, it is located in a range overlapping with the seat plate 7. In this embodiment, the protrusion 13 is formed in a block shape and arranged in a circumferential direction, for example, as shown in FIG. 3 . The block-shaped protrusions 13 are formed in a rectangular shape when viewed from the front, and the positions of at least two of the protrusions 13 are set so that the smaller angle between them when viewed in the circumferential direction of the joint pipe 6 is greater than 90°. That is, at least one protrusion 13 is located in each of two regions of the outer circumferential surface of the coupling pipe 6 that are divided by a diameter perpendicular to the diameter of the coupling pipe 6 through which at least one of the protrusions 13 passes. Preferably, the block-shaped protrusions 13 are arranged rotationally symmetrically or approximately rotationally symmetrically when viewed in the axial direction of the coupling pipe 6. The positions of the ends 13a of these block-shaped protrusions 13 are set so that they do not shift from each other in the axial direction of the coupling pipe 6.

[0021] The lower column 3, like the upper column 2, is a centrifugally formed prestressed concrete column. The lower column 3 is cylindrical, with multiple tendons embedded circumferentially in the axial direction, and seat plates integrated at both ends. In this embodiment, the lower column 3 is tapered, gradually increasing in diameter from its upper end to its lower end, and is connected to the upper column 2 by being inserted into the fitting portion 16 of the joint pipe 6. Within the joint pipe 6, the seat plate 7 of the upper column 2 and the seat plate of the lower column 3 face each other while being spaced apart from each other. In other words, the upper column 2 and the lower column 3 are not in contact with each other. Note that the shape of the lower column 3 is not limited to a tapered shape along the entire axial direction. As long as the upper end, which is fitted into the joint pipe 6, has a tapered shape that gradually increases in diameter downward, the shape of the remaining portion not inserted into the joint pipe 6 may be straight or any other shape. Note that the lower end of the lower column 3 may be erected underground, which is the installation surface, or may be connected to a separate lower column.

[0022] Next, a method for manufacturing the upper pillar 2 will be described.

[0023] A formwork 18 for a centrifugal molding machine shown in Fig. 1 is used to manufacture the upper column 2. The formwork 18 integrally comprises a cylindrical formwork main body 20 for forming the concrete portion 5 (Fig. 2) and a flange 21 formed at one end of the formwork main body 20 as an abutment for applying tension to the tendon 10.

[0024] The formwork main body 20 is formed in accordance with the shape of the concrete part 5 (Fig. 2), and in this embodiment is formed in a tapered shape that gradually widens in diameter from the other end to one end.

[0025] The flange 21 is formed to protrude in the radial direction at one end of the form body 20. The flange 21 is continuous around the entire periphery of the form body 20, for example.

[0026] Then, the joint pipe 6 is installed in the formwork 18 so as to correspond to the lower end of the upper column 2. At this time, the joint pipe 6 is positioned so that the end 13a of the protrusion 13 abuts against the end of the formwork 18, which in this embodiment is the flange 21. In addition, one end of the tendon 10 is fixed to the seat plate 7 inside the joint pipe 6, and the other end is inserted into the seat plate or a jig similar to a seat plate.

[0027] In this state, tension is applied by pulling the other end of the tendon 10 using a tensioning means such as a jack. At this time, the end 13a of the protruding portion 13 of the joint pipe 6, which is pulled together with the seat plate 7, hits and is supported by the flange 21 of the formwork 18, thereby acting as an anchor to prevent the joint pipe 6 from moving in the tensioning direction.

[0028] In this state, concrete is poured into the form body 20 of the form 18, and after a predetermined amount has been filled, the form 18 is closed by a closing means (not shown).

[0029] The formwork 18 is then placed in a centrifugal molding machine and rotated, and centrifugal compaction using the centrifugal force is carried out to form the upper column 2 in which the concrete portion 5 shown in Figure 2 is integrated with the joint pipe 6.

[0030] After the molding is completed, the blocking means is removed and unhardened concrete, so-called slag, is discharged from the formwork 18, the formwork 18 is placed in a curing tank and subjected to normal pressure steam curing, after which the tension applied by the tensioning means is gradually released and the upper column 2 is removed from the formwork 18 with tension applied to the concrete part 5.

[0031] The upper column 2 manufactured in this manner is joined to the lower column 3 that has been centrifugally formed separately using a centrifugal forming machine to assemble the prefabricated concrete 1. This work is performed using, for example, a column erection vehicle. First, the lower end of the lower column 3 is erected into the ground, which is the installation surface, and then the upper column 2 is lifted up using the column erection vehicle, and the lower end face of the upper column 2 is aligned and positioned opposite the upper end face of the lower column 3. The upper column 2 is then lowered so that the upper end of the lower column 3 is inserted from below into the joint pipe 6 integrated with the lower end of the upper column 2, and the tapered inner surface of the joint pipe 6 is fitted so as to closely contact the outer surface of the upper end of the lower column 3, which has the same or approximately the same gradient.

[0032] Next, the effects of the first embodiment will be described.

[0033] According to this embodiment, the joint pipe 6, which is integrally formed with the seat plate 7, is placed in the formwork 18 with the radially protruding protrusion 13 from the outer periphery of the main body 12 abutting against one end of the formwork 18. Concrete is poured into the formwork 18 with the tendon 10, whose end is fixed to the seat plate 7, tensioned toward the other end of the formwork 18. Centrifugal molding is then performed to integrate the concrete portion 5 with the joint pipe 6. This allows the tension of the tendon 10 to be maintained by the joint pipe 6 during molding of the concrete portion 5 without the end of the joint pipe 6 abutting against the formwork 18, and does not damage the end of the joint pipe 6 or its rust-proofing treatment. This prevents deterioration that is difficult to detect, such as rust progressing from the end of the joint pipe 6 to the inside of the joint pipe 6, which is difficult to visually inspect. Furthermore, since no special tool or the like is required to maintain the tension of the tendon 10, the upper column 2 can be manufactured with a simple configuration.

[0034] For example, by forming the protruding portion 13 in a block shape, the protruding portion 13 can be minimized, which allows the weight of the joint pipe 6 to be reduced and the material cost to be reduced, allowing for inexpensive production.

[0035] In addition, since the protrusion 13 has a simple configuration, there is no need for a large-scale formwork configuration or special jigs to maintain the tension of the tendon 10, which is expected to reduce manufacturing costs.

[0036] In the first embodiment, the protrusion 13 may have various other functions. For example, as in a second embodiment shown in Fig. 4, an attachment portion 24 may be formed on the outer surface of the protrusion 13, and a bolt 25, such as a scaffolding bolt, may be detachably connected to the attachment portion 24 by screwing or the like. Furthermore, as in a third embodiment shown in Fig. 5, the protrusion 13 may be formed with a holding portion 27 that holds a conduit 26 for accommodating at least a portion of an electric wire, and a hole 29 through which a string-like fixing means 28 for fixing the conduit 26 to the holding portion 27 is inserted, so that the protrusion 13 has the function of supporting the conduit 26 abutted against the holding portion 27 with the string-like fixing means 28.

[0037] Furthermore, the protrusion 13 is not limited to a block shape, and may be formed in a ring shape that continues in the circumferential direction of the coupling pipe 6, as in the fourth embodiment shown in Figure 6. This ring-shaped protrusion 13 continues in the circumferential direction of the outer circumferential surface of the coupling pipe 6 over at least one-quarter of the circumference, and preferably over half the circumference. With this configuration, the position of the end 13a of the protrusion 13 can be easily kept constant or approximately constant in the axial direction of the main body 12 of the coupling pipe 6, and approximately the entire end 13a of the protrusion 13 can be reliably abutted against the end of the form 18, which in this embodiment is the flange 21. This fourth embodiment may be combined with the second and / or third embodiments. [Explanation of symbols]

[0038] 1. Prefabricated concrete pillars 2 Upper pillar 5 Concrete section 6. Joint pipe 7 Seat board 10 Tensors 12 Main body 13 Protrusion 18 Formwork 24 Mounting part 25 volts 26 Conduit

Claims

1. A method for manufacturing an upper column for a prefabricated concrete column, the method comprising: a cylindrical concrete section; a coupling pipe integrally arranged on the outer periphery of one end of the concrete section; a seat plate fixed to the inside of the coupling pipe; and a tendon embedded in the concrete section with its end fixed to the seat plate, the coupling pipe having a cylindrical main body section into which a lower column is inserted; and a protrusion arranged on the outer periphery between both ends of the main body section so as to protrude radially, Using a cylindrical formwork, The joint pipe integrally formed with the seat plate is placed in the formwork with the protruding portion abutting against one end of the formwork, The end of the tension member is fixed to the seat plate, and concrete is poured into the formwork under tension toward the other end of the formwork, and centrifugal molding is performed to integrate the concrete portion with the joint pipe. A method for manufacturing the upper column of a prefabricated concrete column.

2. An upper column for a prefabricated concrete column that is connected to a lower column to form a prefabricated concrete column, A cylindrical concrete section, a joint pipe disposed integrally on the outer periphery of one end of the concrete section; a seat plate fixed to the inside of the joint pipe; and a tension member whose end is fixed to the seat plate and embedded in the concrete portion, The coupling pipe is a cylindrical main body into one end of which the lower pillar is inserted; a protrusion disposed on the outer periphery of the main body between both ends thereof so as to protrude in the radial direction; The upper column of a prefabricated concrete column is characterized by:

3. The protrusions are block-shaped and are formed on the outer periphery of the main body.

3. The upper column of a prefabricated concrete column according to claim 2.

4. The protrusion is a ring-shaped portion that is connected to the outer periphery of the main body in the circumferential direction.

3. The upper column of a prefabricated concrete column according to claim 2.

5. The protrusion has a mounting portion to which a bolt can be attached.

3. The upper column of a prefabricated concrete column according to claim 2.

6. The protrusion functions to support a conduit for receiving at least a portion of the wire.

3. The upper column of a prefabricated concrete column according to claim 2.

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