JP7698446B2 - Unbonded precast prestressed concrete columns and precast concrete columns - Google Patents

Description

One embodiment of the present invention relates to an unbonded precast prestressed concrete column. Another embodiment of the present invention relates to a precast concrete column body that forms an unbonded precast prestressed concrete column.

An unbonded prestressed concrete structure is a structure in which tension members inserted into sheath pipes are tensioned (prestressed) with hydraulic jacks or similar. Prestressing imparts compressive stress to the concrete, offsetting the tensile stress that occurs in the concrete due to bending stress caused by fixed loads and live loads, resulting in a concrete cross-section in which no tensile stress occurs.

Concrete fitted with tension members has been used primarily as building beams, but in recent years, its use as building columns has been expanding (see, for example, Patent Document 1).

JP 2019-19664 A

Concrete columns fitted with tension members have excellent earthquake resistance because the prestress force is maintained and the tension members can deform along their entire length when vibrations occur in the building. However, in the unlikely event that the tension members in the concrete columns break, the prestress is no longer maintained and there is a risk of significant damage to the building. For this reason, there has been a demand for concrete columns with an unbonded prestressed concrete structure that is highly earthquake-resistant and safe.

In view of the above problems, one embodiment of the present invention aims to provide an unbonded precast prestressed concrete column that is highly earthquake-resistant and safe.

An unbonded precast prestressed concrete column according to one embodiment of the present invention includes a plurality of precast concrete column bodies arranged vertically, tension members inserted into the precast concrete column bodies in an unbonded state, and assembly bars embedded in the precast concrete column bodies, and the assembly bars include unattached portions that are not attached to the concrete within the precast concrete column bodies.

The precast concrete column according to one embodiment of the present invention is a precast concrete column arranged in a vertical direction to form an unbonded precast prestressed concrete column, and includes a tension member inserted into the concrete in an unbonded state and an assembly bar embedded in the concrete, and the assembly bar includes an unattached portion that is not attached to the concrete.

The precast concrete column may include a joint where the beam is joined, and the unattached portion may be provided in at least a portion of the joint.

The assembly reinforcement may be covered with a covering material at the unattached portion.

The covering material may be elastic.

The covering material may be clay, vinyl tape, or butyl rubber.

The unbonded precast prestressed concrete column may further include transverse reinforcement embedded within the precast concrete column body, and the transverse reinforcement may be in contact with the covering material.

The tension member may be located inside the assembly reinforcement.

Assembly reinforcement may be provided at the four corners of the precast concrete column.

The unbonded precast prestressed concrete column of one embodiment of the present invention has excellent safety and earthquake resistance.

FIG. 1 is a schematic diagram of a building including an unbonded precast prestressed concrete column according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing two joints in an unbonded precast prestressed concrete column according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a joint of an unbonded precast prestressed concrete column according to one embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the joint of a precast concrete column body of an unbonded precast prestressed concrete column according to one embodiment of the present invention. FIG. 2 is a schematic diagram showing a joint of an unbonded precast prestressed concrete column according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of a PC member of an unbonded precast prestressed concrete column according to one embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the fixing of assembly reinforcement at a joint of a precast concrete column body of an unbonded precast prestressed concrete column according to one embodiment of the present invention. 1 is a schematic diagram illustrating the connection of PC members at a joint of a precast concrete column body of an unbonded precast prestressed concrete column according to one embodiment of the present invention. FIG. FIG. 2 is a schematic cross-sectional view of a joint of an unbonded precast prestressed concrete column according to one embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a joint of a precast concrete column according to one embodiment of the present invention. FIG. 1 is a schematic diagram illustrating an unbonded precast prestressed concrete column according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a joint in an unbonded precast prestressed concrete column according to an embodiment of the present invention. 1 is a plan cross-sectional view of a structure according to one embodiment of the present invention; 1 is a plan cross-sectional view of a structure according to one embodiment of the present invention; FIG. 2 is a schematic cross-sectional view illustrating a structure according to one embodiment of the present invention.

Each embodiment of the present invention will be described below with reference to the drawings. Note that the embodiments are merely examples, and any embodiment that a person skilled in the art could easily come up with by making appropriate modifications while maintaining the gist of the invention is naturally included within the scope of the present invention. Also, in order to make the explanation clearer, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment. However, the shapes shown in the drawings are merely examples and do not limit the interpretation of the present invention.

For the sake of convenience, the present specification uses the terms "above," "upper," "upper part," "below," "lower," and "lower part" to describe the hierarchical relationship of each component. For example, when describing the positional relationship of components of a structure (such as a concrete pillar), the normal use of the structure is used as the basis, and the side facing the ground in the vertical direction may be referred to as "lower," "lower," or "lower part."

In this specification, the letters "first," "second," "third," and "fourth" attached to each component are convenient labels used to distinguish each component, and have no other meaning unless otherwise specified.

In this specification and drawings, the same reference numerals are used to collectively represent multiple identical or similar components, and capital or lower case letters may be added to distinguish between the multiple components. In addition, a hyphen and a natural number may be used to distinguish between multiple parts of a single component.

In this specification, "assembly reinforcement" refers to a reinforcing bar in which one end is in contact with the outermost horizontal reinforcement bar on one end of the precast concrete column in the longitudinal direction and protrudes from that end, and the other end protrudes into a recess provided on the other end of the precast concrete column. It also includes a reinforcing bar that is in contact with the outermost horizontal reinforcement bar on one end of the precast concrete column and the outermost horizontal reinforcement bar on the other end of the precast concrete column, among the multiple horizontal reinforcement bars arranged in the longitudinal direction within the precast concrete column.

The following embodiments may be combined with each other as long as no technical contradiction occurs.

First Embodiment
1 to 8, an unbonded precast prestressed concrete column 20 according to one embodiment of the present invention will be described.

[1. Configuration of unbonded precast prestressed concrete column 20]
FIG. 1 is a schematic diagram of a building 10 including an unbonded precast prestressed concrete column 20 according to an embodiment of the present invention. As shown in FIG. 1, the building 10 includes an unbonded precast prestressed concrete column 20 extending in the vertical direction and a concrete beam 30. In other words, the building 10 is a structure including an unbonded precast prestressed concrete column 20 and a concrete beam 30. The unbonded precast prestressed concrete column 20 has a configuration in which a plurality of precast concrete columns 100 are arranged in the vertical direction and joined at a joint 200. In addition, the concrete beam 30 is joined to the precast concrete column 100 at the joint 300. The position of the joint 300 is not particularly limited, and the joint 300 may be provided on any of the precast concrete columns 100.

Although not shown, a slab is provided in the area surrounded by the concrete beams 30. However, in cases such as an open-ceiling structure, the building 10 may have floors on which no slab is provided.

Figure 2 is a schematic diagram showing joints 200 and 300 in an unbonded precast prestressed concrete column 20 according to one embodiment of the present invention.

As shown in FIG. 2, two precast concrete columns 100 are joined at a joint 200. Details of the joint of the precast concrete columns 100 will be described later. In addition, the concrete beam 30 is joined to the precast concrete columns 100 at a joint 300.

Each of the multiple precast concrete columns 100 includes multiple assembly reinforcements 110, multiple tendons 121, and multiple transverse reinforcements 130. The assembly reinforcements 110 are embedded in the precast concrete column 100, and the tendons 121 are inserted into the precast concrete column 100 in an unbonded state. The transverse reinforcements 130 are embedded in the concrete of the precast concrete column 100 so as to surround the multiple assembly reinforcements 110 in a plane approximately perpendicular to the extension direction of the assembly reinforcements 110.

The assembly reinforcement 110 embedded in the precast concrete column 100 is attached to the concrete that constitutes the precast concrete column 100. However, the unbonded precast prestressed concrete column 20 has an unattached portion 310 where the assembly reinforcement 110 is not attached to the concrete of the precast concrete column 100. For example, as shown in FIG. 2, the unattached portion 310 can be provided in the joint 300. In a building 10 using an unbonded precast prestressed concrete column 20, even if the tension member 121 breaks, at least one of the multiple assembly reinforcements 110 connects the stacked precast concrete columns 100 together, so the building 10 can be supported. However, if the assembly reinforcement 110 is attached to the concrete, local strain is generated in the assembly reinforcement 110 during an earthquake, which may cause tensile yielding. In other words, even though the unbonded precast prestressed concrete column is unlikely to cause residual deformation, there is a risk that residual deformation will remain, as in a reinforced concrete column. In the unbonded precast prestressed concrete column 20, the assembly reinforcement 110 has an unattached portion 310, which suppresses local strain in the assembly reinforcement 110 at the unattached portion 310, making it difficult for tensile yielding to occur. Therefore, by using the unbonded precast prestressed concrete column 20, it is possible to make it difficult for residual deformation to occur in the building 10 after an earthquake. Note that the unattached portion 310 is preferably provided at the column-beam joint (joint 300), where tensile yielding is likely to occur during an earthquake, but it can also be provided at a location other than the joint 300.

In the unattached portion 310, the assembly reinforcement 110 is covered by the covering material 115, and the assembly reinforcement 110 is not attached to the concrete. In addition, when the lateral reinforcement 130 is provided in the unattached portion 310, the lateral reinforcement 130 may be provided on top of the covering material 115 and in contact with the covering material 115.

The covering material 115 may be, for example, clay, vinyl tape, or butyl rubber, but is not limited to these. The covering material 115 only needs to be able to prevent the assembly reinforcement 110 from adhering to the concrete.

Figure 3 is a schematic cross-sectional view of a joint 300 of an unbonded precast prestressed concrete column 20 according to one embodiment of the present invention. Specifically, Figure 3 is a cross-sectional view of an unattached portion 310 of a precast concrete column 100 cut approximately perpendicular to the vertical direction along line A-A' shown in Figure 2.

In a plane approximately perpendicular to the vertical direction, twelve assembly bars 110 are provided in the precast concrete column 100. The assembly bars 110 are preferably provided at the four corners of the precast concrete column 100. One end of each of the four assembly bars 110 located at the four corners of the precast concrete column 100 is inserted into another precast concrete column 100 as shown in FIG. 2 and fixed to the assembly bar 110 of the other precast concrete column 100. That is, the four assembly bars 110 located at the four corners of the precast concrete column 100 are provided across the two precast concrete columns 100 to be joined. On the other hand, the ends of the eight assembly bars 110 located on the sides of the precast concrete column 100 are embedded in the precast concrete column 100. The number of assembly bars 110 is not limited to 12 and can be provided as appropriate.

As described above, in the unattached portion 310, the assembly reinforcement 110 is covered by the covering material 115, so it is not attached to the concrete of the precast concrete column 100. In addition, the horizontal reinforcement 130 is provided on the outside of the assembly reinforcement 110, but in the unattached portion 310, the assembly reinforcement 110 is covered by the covering material 115, so the assembly reinforcement 110 is not in contact with the horizontal reinforcement 130. It is preferable that the unattached portion 310 is provided in the longitudinal direction of the assembly reinforcement 110 from the upper and lower surfaces of the joint 300, each of which is the same length as the column depth or more. Therefore, the unattached portion 310 may be provided in multiple lengths in the longitudinal direction of the assembly reinforcement 110. However, in the joint 300 (column-beam joint) where columns are provided above and below, the assembly reinforcement 110 of the lower column and the assembly reinforcement 110 from the upper column may overlap, and the unattached portion 310 may be approximately the same length as the beam depth. In other words, it is preferable that the unattached portion 310 be provided with a length that is approximately equal to or greater than the beam depth.

Eight tension members 121 are provided inside the precast concrete column 100. The eight tension members 121 are provided inside the assembly reinforcement 110. The eight tension members 121 are prevented from adhering to the concrete of the precast concrete column 100 by a sheath tube, which will be described later, and are in an unbonded state. The number of tension members 121 is not limited to eight, and can be provided as appropriate.

The positions of the assembly reinforcement 110 and the tension member 121 within the precast concrete column 100 are not limited to the configuration shown in FIG. 3. Within the precast concrete column 100, the assembly reinforcement 110 may be provided inside the tension member 121.

[2. Joining of precast concrete column 100]
FIG. 4 is a schematic diagram illustrating the joining of a precast concrete column body 100 of an unbonded precast concrete column according to one embodiment of the present invention.

As shown in FIG. 4, the precast concrete column 100 includes concrete, assembly reinforcement 110, and tension member 121. At one end (first end 101-1) of the precast concrete column 100 in the longitudinal direction, one end of the assembly reinforcement 110 and one end of the tension member 121 protrude from the first end 101-1. It is preferable that the assembly reinforcement 110 protrudes from the first end 101-1 by a length of about 100 mm or more and 500 mm or less. On the other hand, the other end (second end 101-2 side, which is the opposite side of the first end 101-1) of the precast concrete column 100 is provided with a first recess 102-1 and a second recess 102-2. The depths of the first recess 102-1 and the second recess 102-2 are not particularly limited, but the depth of the second recess 102-2 is preferably 200 mm or more and 800 mm or less. As shown in FIG. 3, the depth of the first recess 102-1 may be deeper or shallower than the depth of the second recess 102-2.

The connecting sheath tube 270 is embedded in the first recess 102-1, and the sleeve 210 is embedded in the second recess 102-2. The other end of the tension member 121 is provided so as to protrude in the connecting sheath tube 270. The other end of the assembly reinforcement 110 is provided so as to protrude in the sleeve 210. The other end of the assembly reinforcement 110 and the other end of the tension member 121 are located longitudinally inward from the second end 101-2 of the precast concrete column 100. In other words, the length of the tension member 121 protruding from the precast concrete column 100 into the first recess 102-1 is shorter than the length of the first recess 102-1. The length of the assembly reinforcement 110 protruding from the precast concrete column 100 into the second recess 102-2 is shorter than the length of the second recess 102-2. It is desirable for the assembly bar 110 to protrude into the second recess 102-2 by a length of approximately 100 mm or more and 400 mm or less.

In the unbonded precast prestressed concrete column 20, the second end 101-2 of one precast concrete column 100 and the first end 101-1 of the other precast concrete column 100 are crimped together to form a joint 200. Specifically, the tension member 121 is prestressed to crimp multiple precast concrete columns 100 together. In addition, in the joint 200 of the unbonded precast prestressed concrete column 20, one end of the assembly reinforcing bar 110 protruding from one precast concrete column 100 is inserted into the sleeve 210 of the precast concrete column 100 adjacent in the vertical direction and fixed. In other words, the unbonded precast prestressed concrete column 20 includes the assembly reinforcing bar 110 and the tension member 121 provided across the two precast concrete columns 100 to be joined. In this way, the unbonded precast prestressed concrete column 20 is formed by crimping and joining n (n is a natural number) precast concrete column bodies 100. Note that after prestress is introduced to the tendons 121, no grout is injected between the tendons 121 and the connecting sheath tube 270.

For convenience, in the following description, the second precast concrete column 100-2 may be described as being located on the first precast concrete column 100-1. However, when there is no particular distinction between the first precast concrete column 100-1 and the second precast concrete column 100-2, they will be described as the precast concrete column 100. In addition, for convenience, in the following description, the configuration in which the tension member 121 is inserted into the sheath tube will be described as the PC member. As will be described in detail later, in the PC member, the tension member is arranged in an unbonded state (a state in which a gap is provided between the outer peripheral surface of the tension member and the inner peripheral surface of the sheath tube). In other words, the tension member 121 of the PC member is not in direct contact with the concrete of the unbonded precast prestressed concrete column 20.

In addition, the unbonded state in this embodiment includes a state in which the tendon 121 is not in contact with the concrete of the unbonded precast prestressed concrete column 20 from the beginning, and also includes a case in which, for example, the outer surface of the tendon 121 is processed to be smooth like a mirror, grout is filled in the gap between the outer surface of the tendon 121 and the inner surface of the sheath tube, and the outer surface of the PC member is joined and integrated with the inner surface of the sheath tube via grout when no vibration occurs in the building, but when vibration occurs in the building, the joining is released and the tendon can freely deform in its longitudinal direction inside the sheath tube. In other words, the unbonded state in this embodiment refers to a state in which the tendon 121 can freely deform in its longitudinal direction inside the unbonded precast prestressed concrete column 20 when vibration occurs in the building.

The configuration of the joint 200 of the precast concrete column 100 will be described in further detail with reference to Figures 5 and 6.

Figure 5 is a schematic diagram showing a joint 200 of an unbonded precast prestressed concrete column 20 according to one embodiment of the present invention. Also, Figure 6 is a cross-sectional view of a PC member 120 of an unbonded precast prestressed concrete column 20 according to one embodiment of the present invention. Specifically, Figure 6(A) is a cross-sectional view of the PC member 120 cut along line B-B' shown in Figure 5, and Figure 6(B) is a cross-sectional view of the PC member 120 cut along line C-C' shown in Figure 5.

The first precast concrete column 100-1 includes a plurality of first assembly bars 110-1 and a plurality of first tension members 121-1. The second precast concrete column 100-2 includes a plurality of second assembly bars 110-2 and a plurality of second tension members 121-2. In the following, when there is no particular distinction between the first assembly bars 110-1 and the second assembly bars 110-2, they will be described as assembly bars 110. Similarly, when there is no particular distinction between the first tension members 121-1 and the second tension members 121-2, they will be described as tension members 121.

As shown in FIG. 5, the first PC member 120-1 includes a first tension member 121-1 and a first sheath tube 122-1. The second PC member 120-2 includes a second tension member 121-2 and a second sheath tube 122-2. In the following, when there is no particular distinction between the first PC member 120-1 and the second PC member 120-2, they will be described as PC members 120. Similarly, when there is no particular distinction between the first sheath tube 122-1 and the second sheath tube 122-2, they will be described as sheath tubes 122.

As shown in FIG. 5, the joint 200 also includes a sleeve 210, grout 220, a coupler 230, a support plate 240, a washer 250, a nut 260, a connecting sheath tube 270, a bellows sheath tube 275, an increaser 278, and grease 280.

The sleeve 210 is embedded in the second precast concrete column 100-2. The end of the second assembly bar 110-2 is provided in the sleeve 210, and the end of the first assembly bar 110-1 is inserted into the sleeve 210. Grout 220 is filled in the sleeve 210 and hardened. Therefore, the end of the first assembly bar 110-1 and the end of the second assembly bar 110-2 are fixed by the grout 220 within the sleeve 210.

The sleeve 210 is a joint that can fix the assembly reinforcement 110 by filling it with grout. Therefore, the sleeve 210 is provided with an injection port and a discharge port for injecting grout (not shown in FIG. 4). The injection port and discharge port of the sleeve 210 will be described later together with the explanation of the injection of grout.

It is preferable that one end of the sleeve 210 from which the end of the second assembly bar 110-2 protrudes is closed. For example, the second assembly bar 110-2 provided in the sleeve 210 and one end of the sleeve 210 may be bonded using a sealant to close one end of the sleeve 210. Meanwhile, the other end of the sleeve 210 is open. Therefore, the grout 220 injected into the sleeve 210 enters the gap between the first precast concrete column 100-1 and the second precast concrete column 100-2 from the other end of the sleeve 210.

The grout 220 can be, for example, a cement-based grout material such as mortar, a glass-based grout material such as water glass, or a synthetic resin-based grout material such as epoxy resin.

Before hardening, the grout 220 preferably has a suitable degree of fluidity so that it can be easily injected into the sleeve 210. On the other hand, after hardening, the grout 220 preferably retains high strength. Mortar is preferable as the grout 220 used in the unbonded precast prestressed concrete columns 20 of the building 10. Mortar contains cement. As the cement, for example, Portland cement can be used.

The connecting sheath tube 270 is embedded in the first recess 102-1 (see FIG. 2) of the second precast concrete column 100-2. The end of the second tendon 121-2 is provided inside the connecting sheath tube 270, and the end of the first tendon 121-1 is inserted into the connecting sheath tube 270. The connecting sheath tube 270 is filled with grease 280.

One end of the connecting sheath tube 270, where the end of the second tendon 121-2 is provided, is preferably closed to prevent leakage of the filled grease 280. As shown in FIG. 5, one end of the connecting sheath tube 270 is capped by an increaser 278. Meanwhile, the other end of the connecting sheath tube 270 is preferably closed to prevent the grout 220 from entering. As shown in FIG. 5, a bellows sheath tube 275 may be provided at the other end of the connecting sheath tube 270 to close the space between the connecting sheath tube 270 and the support plate 240.

The configuration of the other end of the connecting sheath tube 270 is not limited to this. The configuration of one end and the other end of the connecting sheath tube 270 may be configured such that the grease 280 does not leak out and the contact between the first tension member 121-1 and the grout 220 can be prevented. For example, one end of the connecting sheath tube 270 and the second sheath tube 122-2 may be bonded using a sealing material, and one end of the connecting sheath tube 270 may be closed. The other end of the connecting sheath tube 270 and the support plate 240 may be bonded using a sealing material. Mortar may be used instead of the sealing material. By preventing the intrusion of the grout 220 into the connecting sheath tube 270, the contact between the first tension member 121-1 and the second tension member 121-2 and the grout 220 can be prevented. In addition, by preventing contact with the grout 220, corrosion of the first tendon 121-1 and the second tendon 121-2 can be suppressed.

As shown in FIG. 6(B), the PC member 120 includes a tension member 121, a sheath tube 122, and a protective layer (sheath) 123. The protective layer 123 has the function of protecting the tension member 121 from external water and oxygen. In other words, the protective layer 123 can prevent corrosion of the tension member 121. Therefore, the durability of the PC member 120 is improved. The material of the protective layer 123 is, for example, an organic resin such as polyethylene. Note that the protective layer 123 may be composed of multiple layers.

As shown in FIG. 6(A), the protective layer 123 covering the tension member 121 is removed in the connecting sheath tube 270. Therefore, grease 280 is filled in to prevent corrosion of the tension member 121. In the connecting sheath tube 270, the first sheath tube 122-1 is removed from the first PC member 120-1, exposing the first tension member 121-1. In the second PC member 120-2, a portion of the second sheath tube 122-2 is also removed, exposing the second tension member 121-2. In addition, in the connecting sheath tube 270, the first tension member 121-1 of the first PC member 120-1 and the second tension member 121-2 of the second PC member 120-2 are each screwed into the coupler 230. That is, the first tension member 121-1 of the first PC member 120-1 and the second tension member 121-2 of the second PC member 120-2 are connected via a coupler 230.

The first tendon 121-1 of the first PC member 120-1 protrudes from the end of the first precast concrete column 100-1. A support plate 240 with a through hole is arranged at the end of the first precast concrete column 100-1, and the first tendon 121-1 protruding from the end of the first precast concrete column 100-1 passes through the through hole of the support plate 240. The protruding first tendon 121-1 is inserted into a washer 250 arranged on the support plate 240 and is screwed with a nut 260 arranged on the washer 250. In other words, the exposed first tendon 121-1 of the first PC member 120-1 is screwed with the nut 260, and the end of the first tendon 121-1 is fixed to the end of the first precast concrete column 100-1.

The support plate 240 is fixed to the concrete of the first precast concrete column 100-1 and has the function of transmitting the tension of the first tension member 121-1 to the concrete. The size of the support plate 240 is preferably larger than the diameter of the first PC member 120-1 and larger than the diameter of the connecting sheath tube 270. As shown in FIG. 4, the support plate 240 may or may not be provided in a recess in the first precast concrete column 100-1. The shape of the support plate 240 is, for example, rectangular, but the configuration of the shape of the support plate 240 is not limited to this. The shape of the support plate 240 may be, for example, circular.

The sheath tube 122 can be, for example, a steel sheath tube or a polyethylene sheath tube, but a polyethylene sheath tube is preferred for the PC member 120. Since a polyethylene sheath tube is resistant to corrosion, a PC member 120 using a polyethylene sheath tube for the sheath tube 122 has improved durability.

In Figures 2 to 6, the configuration of the unbonded precast prestressed concrete column 20 is described in which the first assembly bar 110-1 protruding from the first precast concrete column 100-1 is inserted into the second precast concrete column 100-2 located above the first precast concrete column 100-1. However, the unbonded precast prestressed concrete column 20 can also be configured in such a way that the second assembly bar 110-2 protruding from the second precast concrete column 100-2 is inserted into the first precast concrete column 100-1 located below the second precast concrete column 100-2.

Figure 7 is a schematic diagram illustrating the fixation of assembly reinforcement 110 at the joint 200 of the precast concrete column body 100 of an unbonded precast prestressed concrete column 20 according to one embodiment of the present invention.

As shown in FIG. 7, the sleeve 210 is provided with an inlet 211 and an outlet 212 that connect the space within the sleeve 210 inside the second precast concrete cylinder 100-2 to the space outside the second precast concrete cylinder 100-2.

The inlet 211 and the outlet 212 are openings for injecting and discharging the grout 220 after the second precast concrete column 100-2 is installed on the first precast concrete column 100-1. The grout 220 is injected from the inlet 211 to fill the space in the sleeve 210 and the space between the first precast concrete column 100-1 and the second precast concrete column 100-2, and the excess grout 220 is discharged from the outlet 212. The inlet 211 is provided below the outlet 212. By positioning the inlet 211 below the outlet 212, it is possible to push out air from below, thereby reducing air pockets in the space. However, the inlet 211 can also be provided above the outlet 212. Also, multiple outlets 212 can be provided.

The space between the first precast concrete column 100-1 and the second precast concrete column 100-2 is blocked by the backing plate 290, forming a closed space. Therefore, the injected grout 220 is blocked by the backing plate 290 and does not leak out to the outside of the first precast concrete column 100-1 and the second precast concrete column 100-2. The backing plate 290 can be installed on the outside of the first precast concrete column 100-1 and the second precast concrete column 100-2 before the grout 220 is injected. Note that the backing plate 290 can be removed after the grout 220 has hardened.

Figure 8 is a schematic diagram illustrating the connection of a PC member 120 at a joint 200 of a precast concrete column body 100 of an unbonded precast prestressed concrete column 20 according to one embodiment of the present invention.

As shown in FIG. 8, the connecting sheath tube 270 is provided with an inlet 271 and an outlet 272 that connect the space inside the connecting sheath tube 270 inside the second precast concrete cylinder 100-2 to the space outside the second precast concrete cylinder 100-2.

The inlet 271 and the outlet 272 are openings for injecting and discharging grease 280 after the first tension member 121-1 of the first PC member 120-1 and the second tension member 121-2 of the second PC member 120-2 are connected by the coupler 230. The grease 280 is injected from the inlet 271 and fills the space inside the connecting sheath tube 270, and excess grease 280 is discharged from the outlet 272. The inlet 271 is provided above the outlet 272. However, the inlet 271 can also be provided below the outlet 272. Also, multiple inlets 271 and outlets 272 can be provided.

The injected grease 280 is blocked by the support plate 240 and the bellows sheath tube 275 at the lower part of the connecting sheath tube 270, so it does not leak out.

The above explanation is mainly about the assembly of the unbonded precast prestressed concrete column 20 using the precast construction method. That is, the precast concrete column 100 used at the construction site of the building 10 is manufactured in advance in a factory or the like and transported to the construction site of the building 10. In the precast concrete column 100 manufactured in a factory or the like, the assembly reinforcement 110 and the PC member 120 are provided in the concrete. At one end of the precast concrete column 100, one end of the assembly reinforcement 110 and one end of the tension member 121 of the PC member 120 protrude. On the other hand, at the other end of the precast concrete column 100, the sleeve 210 and the connecting sheath tube 270 are embedded, and the other end of the assembly reinforcement 110 is provided in the sleeve 210 so as to be contained within the precast concrete column 100, and the other end of the tension member 121 of the PC member 120 is provided in the connecting sheath tube 270 so as to be contained within the precast concrete column 100. At the construction site of the building 10, multiple precast concrete columns 100 manufactured in a factory are pressure-bonded together to form an unbonded precast prestressed concrete column 20. Using the precast construction method improves work efficiency at the construction site, shortens construction time and costs, and improves workability.

The unbonded precast prestressed concrete column 20 according to this embodiment is an unbonded precast prestressed concrete column 20 in which a first precast concrete column 100-1 and a second precast concrete column 100-2 are joined and extend vertically, and includes a tension member 121 provided across the first precast concrete column 100-1 and the second precast concrete column 100-2, and an assembly bar 110 provided across the first precast concrete column 100-1 and the second precast concrete column 100-2. Therefore, even if the tension member 121 of the PC member 120 breaks, the first precast concrete column 100-1 and the second precast concrete column 100-2 are connected by the assembly bar 110, so that the unbonded precast prestressed concrete column 20 can be maintained as a single unit. Therefore, the collapse of the building 10 including the unbonded precast prestressed concrete column 20 is suppressed, and the safety of the unbonded precast prestressed concrete column 20 is improved. In addition, in the unbonded precast prestressed concrete column 20, the assembly reinforcement 110 has an unattached portion 310, which suppresses the occurrence of local strain in the assembly reinforcement 110 at the unattached portion 310, making tensile yielding less likely to occur. Therefore, by using the unbonded precast prestressed concrete column 20, it is possible to make it less likely that residual deformation will occur in the building 10 after an earthquake.

<Modification 1>
A joint 200A, which is different from the joint 200 of the unbonded precast prestressed concrete column 20 according to the first embodiment, will be described with reference to Fig. 9. Note that in the description of the joint 200A, if the joint 200A has the same configuration as the joint 200, the description may be omitted.

Figure 9 is a schematic cross-sectional view of a joint 200A of an unbonded precast prestressed concrete column 20 according to one embodiment of the present invention. As shown in Figure 9, the first PC member 120-1 includes a first tendon 121-1 and a first sheath tube 122-1. The second PC member 120-2 includes a second tendon 121-2 and a second sheath tube 122-2. The joint 200A also includes a sleeve 210A, grout 220, a coupler 230, a bearing plate 240, a washer 250, a nut 260, a connecting sheath tube 270, a bellows sheath tube 275, an increaser 278, and grease 280.

The sleeve 210A is embedded in the first precast concrete column 100A-1. The end of the first assembly bar 110A-1 is provided in the sleeve 210A, and the end of the second assembly bar 110A-2 is inserted into the sleeve 210A. Grout 220 is filled in the sleeve 210A and hardened. Therefore, the second assembly bar 110A-2 is provided across and fixed to the first precast concrete column 100A-1 and the second precast concrete column 100A-2. Although not shown, the first precast concrete column 100A-1 and the second precast concrete column 100A-2 include an unattached portion where the first assembly bar 110A-1 or the second assembly bar 110A-2 is not attached to the concrete.

In the joint 200A of the unbonded precast prestressed concrete column 20 according to this modified example, the assembly reinforcing bar 110 is inserted into the end of the first precast concrete column 100A-1, and the tension member 121 of the PC member 120 is connected to the end of the second precast concrete column 100A-2. The grout 220 is injected from the end of the first precast concrete column 100A-1, and the grease 280 is injected from the end of the second precast concrete column 100-2, and the positions at which the grout 220 and the grease 280 are injected are different. This reduces the chance of an operator injecting the wrong injection material. In addition, the positions at which the sleeve 210A and the connecting sheath tube 270 are embedded are dispersed, improving the strength of the joint 200A.

<Modification 2>
A precast concrete column 100B and a joint 200B, which are different from the precast concrete column 100 of the unbonded precast prestressed concrete column 20 according to the first embodiment, will be described with reference to Fig. 10. Note that in the description of the precast concrete column 100B and the joint 200B, if the configurations are similar to those of the precast concrete column 100 and the joint 200, the description may be omitted.

Figure 10 is a schematic diagram illustrating the joints of a precast concrete column 100B according to one embodiment of the present invention.

As shown in FIG. 10, the precast concrete column 100B includes a reinforcing bar 510B and a tendon 121B. At the first end 101B-1 side of the precast concrete column 100B, one end of the reinforcing bar 510B and one end of the tendon 121B protrude from the first end 101B-1 of the precast concrete column 100B. On the other hand, at the second end 101B-2 side, which is the opposite side of the first end 101B-1 of the precast concrete column 100B, a first recess 102B-1 and a second recess 102B-2 are provided. A connecting sheath tube 270B is provided in the first recess 102B-1, and a sleeve 210B is provided in the second recess 102B-2.

The other end of the tension member 121B protrudes from inside the connecting sheath tube 270B. On the other hand, the other end of the reinforcing bar 510B does not protrude from inside the sleeve 210. In other words, the other end of the reinforcing bar 510B is embedded in the precast concrete column 100B.

The unbonded precast prestressed concrete column 20 is constructed by vertically crimping the second end 101B-2 of one precast concrete column 100B to another precast concrete column 100B. At this time, the assembly bar 110B protruding from the other precast concrete column 100B is inserted into the sleeve 210B provided on one precast concrete column 100B and fixed in place.

In the joint 200B of the unbonded precast prestressed concrete column 20 according to this modification, a reinforcing bar 510B is provided. That is, the reinforcing bar 510B is provided across the first precast concrete column 100B-1 and the second precast concrete column 100B-2. Therefore, even if the tension member 121 breaks, the first precast concrete column 100B-1 and the second precast concrete column 100B-2 are connected by the reinforcing bar 510B, and can maintain their unity. Therefore, the safety of the unbonded precast prestressed concrete column 20 according to this modification is also improved. In addition, in the unbonded precast prestressed concrete column 20, the assembly bar 110 has an unattached portion 310, which suppresses the occurrence of local strain of the assembly bar 110 in the unattached portion 310, making it difficult for tensile yielding to occur. Therefore, by using unbonded precast prestressed concrete columns 20, residual deformation of the building 10 after an earthquake can be reduced.

Second Embodiment
11 and 12, an unbonded precast prestressed concrete column 20C according to one embodiment of the present invention will be described.

Figure 11 is a schematic diagram showing an unbonded precast prestressed concrete column 20C according to one embodiment of the present invention. Also, Figure 12 is a schematic diagram showing a joint in an unbonded precast prestressed concrete column 20C according to one embodiment of the present invention. Specifically, Figure 12 is a partial enlarged view of area A shown in Figure 11.

11 and 12 show two adjacent unbonded precast prestressed concrete columns 20C (a first unbonded precast prestressed concrete column 20C-1 and a second unbonded precast prestressed concrete column 20C-2). The first unbonded precast prestressed concrete column 20C-1 has a configuration in which a first precast concrete column 100C-1 and a second precast concrete column 100C-2 are joined at a first joint 200C-1 in the vertical direction. The second unbonded precast prestressed concrete column 20C-2 has a configuration in which a third precast concrete column 100C-3 and a fourth precast concrete column 100C-4 are joined at a second joint 200C-2. That is, each of the first unbonded precast prestressed concrete column 20C-1 and the second unbonded precast prestressed concrete column 20C-2 has a configuration in which multiple precast concrete pieces are joined. The precast concrete columns to be joined may have the same structure or different structures. Also, the first unbonded precast prestressed concrete column 20C-1 and the second unbonded precast prestressed concrete column 20C-2 shown in FIG. 11 have structures in which the widths of the concrete columns are different, but they may also have the same structure.

The first unbonded precast prestressed concrete column 20C-1 and the second unbonded precast prestressed concrete column 20C-2 are connected via a damper 35. In addition, each of the first unbonded precast prestressed concrete column 20C-1 and the second unbonded precast prestressed concrete column 20C-2 has a concrete beam 30 connected to the opposite side of the damper 35. Therefore, the first unbonded precast prestressed concrete column 20C-1 and the second unbonded precast prestressed concrete column 20C-2 are connected to the concrete beam 30 and the damper 35 at the first joint 300C-1 and the second joint 300C-2, respectively.

The first joint 300C-1 and the second joint 300C-2 each have a similar configuration to the joint 300 described above. That is, as shown in FIG. 12, the first joint 300C-1 includes an unattached portion 310 where the assembly reinforcement 110 is not attached to the concrete of the second precast concrete column 100C-2. Similarly, the second joint 300C-2 includes an unattached portion where the assembly reinforcement 110 is not attached to the fourth precast concrete column 100C-4.

In a building 10 using an unbonded precast prestressed concrete column 20C to which a damper 35 is connected, the damper 35 can absorb earthquake energy. However, if the assembly reinforcement 110 is attached to the concrete, local strain occurs in the assembly reinforcement 110, resulting in tensile yielding. On the other hand, in an unbonded precast prestressed concrete column 20C having an unattached portion 310, the occurrence of local strain in the assembly reinforcement 110 is suppressed, making tensile yielding less likely to occur. Therefore, by using an unbonded precast prestressed concrete column 20C having an unattached portion 310, it is possible to further reduce the occurrence of residual deformation in the building 10 after an earthquake.

Third Embodiment
Referring to FIG. 13, a structure according to an embodiment of the present invention will be described.

Figure 13 is a plan cross-sectional view of a structure 12 according to one embodiment of the present invention. Specifically, the structure 12 has a structure that combines unbonded precast prestressed concrete columns 20 and concrete beams 30 included in a building 10, and Figure 13 is a cross-sectional view cut along a plane that is approximately perpendicular to the vertical direction so as to include the concrete beams 30.

The structure 12 includes an unbonded precast prestressed concrete column 20, a concrete column 21, and a concrete beam 30. Although the concrete column 21 is an unbonded precast prestressed concrete column, in order to distinguish it from the unbonded precast prestressed concrete column 20, it will be described as a concrete column 21 in this embodiment. The corner columns and side columns of the structure 12 are composed of unbonded precast prestressed concrete columns 20, and the center column of the structure 12 is composed of a concrete column 21. In addition, concrete beams 30 are provided between adjacent unbonded precast prestressed concrete columns 20, between adjacent concrete columns 21, or between adjacent unbonded precast prestressed concrete columns 20 and concrete columns 21. As long as the corner columns and side columns of the structure 12 are composed of unbonded precast prestressed concrete columns 20, the number and arrangement of the unbonded precast prestressed concrete columns 20, concrete columns 21, and concrete beams 30, and the shape of the structure 12 are not limited.

The unbonded precast prestressed concrete column 20 of this embodiment is similar to the unbonded precast prestressed concrete column 20 described in the first embodiment. That is, in the unbonded precast prestressed concrete column 20 of the structure 12, the reinforcing bars and the tension members are each provided across two vertically adjacent precast concrete columns. In addition, the precast concrete column includes an unattached portion 310 where the assembly reinforcement 110 is not attached to the concrete of the precast concrete column. On the other hand, in the concrete column 21 of the structure 12, the tension members are provided across two vertically adjacent precast concrete columns, but the assembly reinforcement is not provided across two vertically adjacent precast concrete columns.

The major difference between the corner columns, side columns, and center columns is the number of concrete beams 30 connected to them. Focusing on one corner column, one side column, and one center column, respectively, two concrete beams 30 are connected to one corner column, three concrete beams 30 are connected to one side column, and four concrete beams 30 are connected to one center column. If all columns of the structure 12 are made of concrete columns 21, the structure 12 may collapse if the tension material breaks. Therefore, in this embodiment, an unbonded precast prestressed concrete column 20 including not only tension material but also assembly reinforcement is applied to the joints of the corner columns and side columns. As a result, even if the tension material of the unbonded precast prestressed concrete column 20 breaks, the unbonded precast prestressed concrete column 20 can be maintained as a single unit because the two precast concrete column bodies are connected by the assembly reinforcement. Therefore, the collapse of the structure 12 can be prevented, and safety is improved. In addition, in the unbonded precast prestressed concrete column 20, the assembly reinforcement 110 has an unattached portion 310, which suppresses local strain in the assembly reinforcement 110 at the unattached portion 310, making tensile yielding less likely to occur. Therefore, by using an unbonded precast prestressed concrete column 20, it is possible to make it less likely for residual deformation to occur in the building 10 after an earthquake.

<Modification 3>
A structure 12D, which is different from the structure 12 according to the second embodiment, will be described with reference to Fig. 14. Note that in the description of the structure 12A, when the structure 12A has the same configuration as the structure 12, the description may be omitted.

Figure 14 is a plan cross-sectional view of a structure 12D according to one embodiment of the present invention. The structure 12D has a core structure. Here, a core structure refers to a structure that gathers equipment such as elevators, stairs, machine rooms, or piping to form the core part of a building. Alternatively, it refers to a structure that concentrates structural members that resist earthquake forces. The core part may be provided across multiple floors.

The structure 12D includes an unbonded precast prestressed concrete column 20, a concrete column 22, a damper 35, a concrete beam 30, and a reinforced concrete column 40. The unbonded precast prestressed concrete column 20 and the concrete column 22 are different in shape, but both are unbonded precast prestressed concrete columns or wall columns. At least one of the unbonded precast prestressed concrete column 20 and the concrete column 22 includes a precast concrete column in which the assembly reinforcement is pressure-bonded across the joint of the precast concrete column body. On the other hand, the reinforced concrete column 40 does not include a tension member. The corner columns and side columns of the structure 12D are composed of the reinforced concrete column 40, and the core part 15 is composed of the unbonded precast prestressed concrete column 20, the concrete column 22, and the damper 35. In the core part 15, the adjacent unbonded precast prestressed concrete column 20 and the concrete column 22 are joined via the damper 35. In addition, concrete beams 30 are joined between adjacent concrete columns 22.

Although the unbonded precast prestressed concrete column 20 and the concrete column 22 of the core part 15 are connected to the damper 35, in the unlikely event that the tension member of the unbonded precast prestressed concrete column 20 or the concrete column 22 breaks, the damper 35 is weaker than the concrete beam 30. Therefore, the structure 12D may collapse significantly, but in this modified example, the core part 15 is composed of the unbonded precast prestressed concrete column 20 or the concrete column 22, which includes not only tension members but also reinforcing bars at the joints. Therefore, in the unlikely event that the tension member breaks, the first precast concrete column body 100-1 and the second precast concrete column body 100-2 are connected by the assembly bar 110, and the unbonded precast prestressed concrete column 20 can be maintained as a single unit. Therefore, the collapse of the structure 12D composed of the unbonded precast prestressed concrete column 20 and the concrete column 22 can be prevented, and safety is improved. In addition, in the unbonded precast prestressed concrete column 20, the assembly reinforcement 110 has an unattached portion 310, which suppresses local strain in the assembly reinforcement 110 at the unattached portion 310, making tensile yielding less likely to occur. Therefore, by using an unbonded precast prestressed concrete column 20, it is possible to make it less likely for residual deformation to occur in the building 10 after an earthquake.

Furthermore, the unbonded precast prestressed concrete column of the structure may be configured by combining different types of precast concrete columns. Different types of precast concrete columns here include precast concrete columns in which the assembly reinforcement and tension members protrude from the precast concrete column, and precast concrete columns in which the tension members protrude from the precast concrete column and the assembly reinforcement does not protrude from the precast concrete column. Therefore, with reference to Figure 15, a structure 12D different from the structure 12 according to the second embodiment will be described.

<Modification 4>
15 is a schematic cross-sectional view illustrating a structure 12E according to an embodiment of the present invention. In the description of the structure 12E, when the structure 12E has the same configuration as the structure 12, the description may be omitted.

The structure 12E may be provided with unbonded precast prestressed concrete columns so that each story 13D includes a different type of precast concrete column. For example, as shown in FIG. 15(A), the unbonded precast prestressed concrete column 20E includes a first precast concrete column 100E-1 belonging to the first story 13E-1, a second precast concrete column 100E-2 belonging to the second story 13E-2 adjacent to the first story 13E-1, a third precast concrete column 100E-3 belonging to the third story 13E-3 adjacent to the second story 13E-2, and a fourth precast concrete column 100E-4 belonging to the fourth story 13E-4 adjacent to the third story 13E-3. In this case, assembly bars 110E and tension members (not shown) are installed across the joint between the first precast concrete column 100E-1 and the second precast concrete column 100E-2 and the joint between the third precast concrete column 100E-3 and the fourth precast concrete column 100E-4, but assembly bars are not installed across the joint between the second precast concrete column 100E-2 and the third precast concrete column 100E-3.

In addition, the structure 12E may have different types of precast concrete columns 100E provided within the story 13E. In other words, when multiple unbonded precast prestressed concrete columns 20E are provided in the horizontal direction, it is sufficient that the assembly reinforcement 110E is provided across any one of the joints of the multiple precast concrete columns 100E provided on the same horizontal plane. For example, as shown in FIG. 15(B), the first unbonded precast prestressed concrete column 20E-1 includes a first precast concrete column 100E-1 belonging to the first story 13E-1, a second precast concrete column 100E-2 belonging to the second story 13E-2 adjacent to the first story 13E-1, and a third precast concrete column 100E-3 belonging to the third story 13E-3 adjacent to the second story 13E-2, and the second unbonded precast prestressed concrete column 20E-2 includes a fourth precast concrete column 100E-4 belonging to the first story 13E-1, a fifth precast concrete column 100E-5 belonging to the second story 13E-2, and a sixth precast concrete column 100E-6 belonging to the third story 13E-3. In this case, since the assembly bar 110E and the tension member (not shown) are provided across the joint between the first precast concrete column 100E-1 and the second precast concrete column 100E-2, the assembly bar does not have to be provided across the joint between the fourth precast concrete column 100E-4 and the fifth precast concrete column 100E-5. Since the assembly bar 110E and the tension member (not shown) are provided across the joint between the fifth precast concrete column 100E-5 and the sixth precast concrete column 100E-6, the assembly bar does not have to be provided across the joint between the second precast concrete column 100E-2 and the third precast concrete column 100E-3. The assembly bar 110E may be a secondary bar.

The first unbonded precast prestressed concrete column 20E-1 and the second unbonded precast prestressed concrete column 20E-2 described above may differ in size or shape. Therefore, for example, the configuration of the structure 12E can be applied to the configuration of the unbonded precast prestressed concrete column 20 and the concrete column 22 of the structure 12D of the above-mentioned modified example 3.

The above-described embodiments of the present invention may be combined as appropriate to the extent that they are not mutually inconsistent. Furthermore, those in which a person skilled in the art has appropriately added or removed components or modified designs, or added or omitted steps or modified conditions based on the respective embodiments, are also included within the scope of the present invention as long as they include the gist of the present invention.

Even if there are other effects and advantages different from those provided by the above-mentioned embodiments, if they are clear from the description in this specification or can be easily predicted by a person skilled in the art, they are naturally understood to be provided by the present invention.

10: Building, 12, 12A, 12D, 12E: Structure, 13D, 13E: Floor, 13E-1: First floor, 13E-2: Second floor, 13E-3: Third floor, 13E-4: Fourth floor, 15: Core, 20, 20C, 20E: Unbonded precast prestressed concrete column, 20C-1, 20E-1: First unbonded precast prestressed concrete column, 20C-2, 20E-2: Second unbonded precast prestressed concrete column, 21, 22: Concrete column, 30: Concrete beam, 35: Damper, 40: Reinforced concrete column, 100, 100B, 100E: Precast concrete column, 100-1, 100A-1, 100B-1, 100C-1, 100E-1: first precast concrete column, 100-2, 100A-2, 100B-2, 100C-2, 100E-2: second precast concrete column, 100C-3, 100E-3: third precast concrete column, 100C-4, 100E-4: fourth precast concrete column, 100E-5: fifth precast concrete column, 100E-6: sixth precast concrete column, 101-1, 101B-1: first end, 101-2, 101B-2: second end, 102-1, 102B-1: first recess, 102-2, 102B-2: second recess, 110, 110B, 110E: assembly bars, 110-1, 110A-1: first assembly bars, 110-2, 110A-2: second assembly bars, 115: covering material, 120: PC member, 120-1: first PC member, 120-2: second PC member, 121, 121B: tension members, 121-1: first tension members, 121-2: second tension members, 122: sheath tube, 122-1: first sheath tube, 122-2: second sheath tube, 123: protective layer, 130: transverse reinforcement bars, 200, 200A, 200B: joints, 200C-1: first joints, 200C-2: second joints, 210, 210A, 210B: Sleeve, 211: Inlet, 212: Outlet, 220: Grout, 230: Coupler, 240: Support plate, 250: Washer, 260: Nut, 270, 270B: Connecting sheath tube, 271: Inlet, 272: Outlet, 275: Bellows sheath tube, 278: Increaser, 280: Grease, 290: Plate, 300: Joint, 300C-1: First joint, 300C-2: Second joint, 310: Unattached part, 510B: Auxiliary reinforcement

Claims (12)

A plurality of precast concrete columns arranged vertically;
A tendon inserted into the precast concrete column in an unbonded state;
An assembly reinforcement embedded in the precast concrete column and extending from one end of the precast concrete column to a recess provided on the other end thereof,
The assembly reinforcement includes an unbonded portion that is not bonded to concrete within the precast concrete column body, which is an unbonded precast prestressed concrete column. The precast concrete column includes a joint connected to a beam,
2. The unbonded precast prestressed concrete column according to claim 1, wherein the unbonded portion is provided in at least a portion of the joint. An unbonded precast prestressed concrete column according to claim 1 or claim 2, in which the assembly reinforcement is covered with a covering material at the unattached portion. An unbonded precast prestressed concrete column as described in claim 3, wherein the covering material is an elastic body. The unbonded precast prestressed concrete column of claim 3, wherein the covering material is clay, vinyl tape, or butyl rubber. Further, a horizontal reinforcement bar is embedded in the precast concrete column,
6. An unbonded precast prestressed concrete column according to claim 3, wherein the transverse reinforcement is in contact with the cladding. An unbonded precast prestressed concrete column according to any one of claims 1 to 6, wherein the tendons are provided on the inside of the assembly reinforcement. An unbonded precast prestressed concrete column according to any one of claims 1 to 7, wherein the assembly reinforcement is provided at the four corners of the precast concrete column body. A precast concrete column body arranged in a vertical direction to form an unbonded precast prestressed concrete column,
A tendon inserted into concrete in an unbonded state;
and an assembly reinforcement embedded in the concrete and extending from one end of the precast concrete column to a recess provided on the other end thereof;
The precast concrete column includes an unattached portion of the assembly reinforcement that is not attached to the concrete. The precast concrete column according to claim 9, wherein the assembly reinforcement is covered with a covering material at the unattached portion. The precast concrete column according to claim 10, wherein the covering material is an elastic material. The precast concrete column of claim 10, wherein the covering material is clay, vinyl tape, or butyl rubber.

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