JP7749898B2 - PCa joint members - Google Patents

Description

The present invention relates to PCa joint members.

For example, when using on-site concrete pouring to construct column joints between upper and lower floors of reinforced concrete (RC) structures, column-to-beam joints between RC columns, or column-beam joints in hybrid structures between RC columns and steel beams, construction time can be lengthened. This issue becomes even more pronounced in high-rise buildings. Therefore, a construction method is sometimes used in which the columns or column-to-joints on both floors are made of precast concrete (hereinafter referred to as "PCa"), and the PCa columns and PCa joints (both included in PCa members) are transported to the site and assembled to form PCa joint members, thereby integrating the components with minimal grouting. This construction method for PCa joint members significantly shortens construction time, including for high-rise buildings. Furthermore, because continuous column and column-beam joints between upper and lower floors are formed using PCa members, it becomes possible to construct buildings with high structural reliability. Among the methods for constructing PCa joint members, precast prestressed concrete (hereinafter referred to as "PCaPC") joint members can be constructed by tensioning and fastening PCa members together with tendons such as PC (Prestressed Concrete) steel bars or PC steel wires, thereby further shortening construction time. In this specification, PCaPC joint members are considered to be included in PCa joint members, and their constituent PCaPC members are considered to be included in PCa members.

The above-mentioned PCa members have multiple sheath tubes inside them, and when PCa members are joined together, the corresponding sheath tubes are connected to form a communicating sheath tube. Tendons are inserted into the communicating sheath tubes and tensioned, and then grout is filled into the communicating sheath tubes to bond the tendons. This generally results in the PCa members being connected together using multiple tensioned, bonded tendons. However, filling the communicating sheath tubes with grout is a time-consuming process, and this issue becomes more pronounced as the number of communicating sheath tubes increases and the number of grout-filled areas increases due to the rise of taller buildings. Furthermore, there is the issue that the curing period required for the grout filled in the communicating sheath tubes to develop the required strength can have a significant impact on the length of the construction period.

Patent Document 1 proposes a high-rise building equipped with precast prestressed concrete columns. This high-rise building is equipped with multiple precast prestressed concrete columns with tension members inserted vertically into the concrete column bodies, and multiple vibration control devices that suppress the swaying of the building. The precast prestressed concrete columns have tension members arranged in an unbonded state in the concrete column bodies, and the vibration control devices suppress the swaying of the high-rise building by keeping deformation of the tension members due to the swaying of the high-rise building within the elastic range of the tension members.

Japanese Patent Application Laid-Open No. 2019-19664

In the high-rise building described in Patent Document 1, the use of unbonded tendons can solve the above-mentioned problems that occur when filling grout. However, when the tendons are tensioned in an unbonded state inside the sheath tube, the tendons are not protected by grout, which can lead to issues with rusting of the tendons in the joint areas of the PCa members. Furthermore, when the building deforms during an earthquake, there is a risk that the tendons will collide with the sheath tube in the joint areas, causing damage.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a PCa joint member in which PCa members are joined together using unbonded tendons, which can suppress or prevent rusting of the tendons in the joint area between the PCa members and damage caused by the tendons colliding with the sheath tube.

In order to achieve the above object, one aspect of the PCa joint member according to the present invention is:
A PCa joint member in which PCa members made of precast concrete and having a plurality of sheath pipes are joined to each other while communicating the corresponding sheath pipes to form a communicating sheath pipe,
Tendons are inserted into all of the communicating sheath tubes, and the tendons are tensioned in an unbonded state;
The tension member is characterized in that a rust preventative material is applied to the joint area spanning the joint interface of at least two of the PCa members.

According to this aspect, in a PCa joint member in which a tendon is tensioned in an unbonded state in a communicating sheath pipe formed by the sheath pipes of the PCa members that are joined to each other, a rust preventative is applied to the joint area of the tendon that spans the joint interface of at least two PCa members, thereby suppressing or preventing rusting in the joint area of the tendon.

Here, "a joint area spanning the joint interface" refers to an area spanning the joint interface within each of the two PCa members, for example, a range of several centimeters to several tens of centimeters. Furthermore, "applying to a joint area spanning the joint interface of at least two PCa members" refers to applying the anti-corrosion material only to the joint area, as well as to applying it to the entire area of a tendon. Taking into account both the risk of rust in the tendon in the joint area and cost, it is preferable to apply the anti-corrosion material only to the joint area of the tendon. As mentioned above, in this embodiment, the PCa joint member includes a PCaPC joint member, the PCa member includes a PCaPC member, the PCa joint includes a PCaPC joint, the PCa column includes a PCaPC column, and the PCa beam includes a PCaPC beam.

Another aspect of the PCa joint member according to the present invention is
A PCa joint member in which PCa members made of precast concrete and having a plurality of sheath pipes are joined to each other while communicating the corresponding sheath pipes to form a communicating sheath pipe,
Tendons are inserted into all of the communicating sheath tubes, and the tendons are tensioned in an unbonded state;
A viscoelastic material is disposed in the gap between the communicating sheath tube and the tension member in a joint region spanning the joint interface of at least two of the PCa members.

According to this aspect, in a PCa joint member in which a tensioning member is tensioned in an unbonded state in a communicating sheath pipe formed by the sheath pipes of the PCa members that are joined to each other, a viscoelastic material is disposed in the joint region of the gap between the communicating sheath pipe and the tensioning member that spans the joint interface of at least two PCa members, thereby suppressing or preventing damage to the tensioning member due to the tensioning member colliding with the sheath pipe in the joint region of at least two PCa members. In this aspect, in addition to a form in which the viscoelastic material is disposed only in the joint region, there is also a form in which it is disposed over the entire area of the tensioning member, but in addition to the joint region, the viscoelastic material may also be disposed in an extracted region where the tensioning member deforms significantly when the building is deformed.

Another aspect of the PCa joint member according to the present invention is
A PCa joint member in which PCa members made of precast concrete and having a plurality of sheath pipes are joined to each other while communicating the corresponding sheath pipes to form a communicating sheath pipe,
Tendons are inserted into all of the communicating sheath tubes, and the tendons are tensioned in an unbonded state;
A rust preventative material is applied to a joint region of the tendon that spans the joint interface between at least two of the PCa members,
A viscoelastic material is disposed in the gap between the communicating sheath tube and the tension member in a joint region spanning the joint interface of at least two of the PCa members.

According to this aspect, in a PCa joint member in which a tendon is tensioned in an unbonded state in a communicating sheath tube formed by the sheath tubes of the PCa members that are joined together, a rust-preventive material is applied to the joint region of the tendon that straddles the joint interface of at least two PCa members, and a viscoelastic material is disposed in the gap between the communicating sheath tube and the tendon in the joint region that straddles the joint interface of at least two PCa members. This makes it possible to suppress or prevent both rust in the joint region of the tendon and damage to the tendon due to the tendon colliding with the sheath tube.

Another aspect of the PCa joint member according to the present invention is
It is characterized in that it further comprises a stiffening material that straddles the joint interface between the two PCa members and surrounds their outer peripheries.

According to this aspect, by further providing a stiffener that straddles the joint interface and surrounds its periphery, the stiffener can prevent the concrete in the cover of the PCa member in the joint area from peeling off. Furthermore, by having the stiffener surround the periphery of the joint area, it is possible to prevent outside air, rainwater, etc. from penetrating into the interface, which also makes it possible to suppress rusting of the tendon.

Another aspect of the PCa joint member according to the present invention is
The rust-preventive material is applied to the entire area of the tendon inserted into the communicating sheath tube.

In this embodiment, by applying the rust-preventive material to the entire area of the tendon, rust development can be suppressed or prevented throughout the entire area of the tendon. Furthermore, when applying the rust-preventive material to the tendon, there is no need to specify the joint area, for example, and apply the material, eliminating the effort required to specify the joint area.

Another aspect of the PCa joint member according to the present invention is
The viscoelastic material is disposed in gaps throughout the entire area of the communicating sheath tube.

In this embodiment, by disposing viscoelastic material in gaps throughout the entire communicating sheath tube, damage caused by collisions with tendons throughout the entire communicating sheath tube can be reduced or prevented. Furthermore, since there is no need to extract areas other than the joint area where the tendons deform significantly during building deformation, for example, and then extract these deformed areas when disposing the viscoelastic material, the effort required for this extraction can be eliminated.

In another aspect of the PCa joint member according to the present invention,
The PCa members to be joined to each other are characterized by being PCa columns and PCa columns.

In this aspect, because all of the PCa members joined together are PCa columns, damage caused by rusting of the tendons and/or collision of the tendons with the sheath tube can be suppressed or prevented, at least in the joint area of the vertically continuous PCa columns.

In another aspect of the PCa joint member according to the present invention,
The PCa members that are joined to each other are characterized by being PCa columns and PCa joints.

In this aspect, because the PCa members joined to each other are a PCa column and a PCa joint, damage caused by rusting of the tendons and/or collision of the tendons with the sheath tube can be suppressed or prevented, at least in the joint area of the column-beam joint.

In another aspect of the PCa joint member according to the present invention,
The PCa members to be joined together are characterized by being PCa beams and PCa beams.

In this aspect, because all of the PCa members joined together are PCa beams, damage caused by rusting of the tendons and/or collision of the tendons with the sheath tube can be suppressed or prevented, at least in the joint areas of the laterally continuous PCa beams.

As can be understood from the above explanation, the PCa joint member of the present invention, in which PCa members are connected to each other by unbonded tendons, can suppress or prevent rusting of the tendons in the joint area between the PCa members and damage caused by the tendons colliding with the sheath tube.

FIG. 2 is a longitudinal cross-sectional view of an example of a PCa joint member according to the first embodiment, showing an enlarged view of the area surrounding the joint region of PCa columns joined to each other. FIG. 2 is a view taken along the line II-II in FIG. 1. A longitudinal cross-sectional view of an example of a PCa joint member according to the second embodiment, which is an enlarged view of the area surrounding the joint region of PCa columns that are joined to each other. A longitudinal cross-sectional view of an example of a PCa joint member according to the third embodiment, which is an enlarged view of the area surrounding the joint region of PCa columns that are joined to each other. A longitudinal cross-sectional view of an example of a PCa joint member related to the fourth embodiment, and an enlarged view of the area around the joint region of PCa columns that are joined to each other.

An example of a PCa joint member according to each embodiment will be described below with reference to the accompanying drawings. Note that in this specification and drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description.

[PCa joint member according to the first embodiment]
First, an example of a PCa joint member according to the first embodiment will be described with reference to Figures 1 and 2. Here, Figure 1 is a longitudinal cross-sectional view of an example of a PCa joint member according to the first embodiment, which is an enlarged view of the periphery of the joint region of PCa columns joined to each other, and Figure 2 is a view taken along the line II-II in Figure 1.

A PCa joint member (PCaPC joint member) 100 is formed by joining a PCa column (PCaPC column) 10 (an example of a PCa member (PCaPC member)) on a lower floor to a PCa column (PCaPC column) 20 (an example of a PCa member (PCaPC member)) on an upper floor. Although not shown here, in addition to the illustrated example, PCa joint members also include joint members between PCa columns (PCaPC columns) and PCa joints (PCaPC joints) and joint members between PCa beams (PCaPC beams). These various PCa joint members form a hybrid frame that makes up a multi-story building.

Here, a "hybrid frame" refers to a structure comprising PCa columns 10, 20, which are precast RC (reinforced concrete) columns, PCa joints (not shown), which are also precast RC joints, and steel beams (not shown) that connect the PCa joints. More specifically, the PCa joints can also be considered to be SRC (steel reinforced concrete) structures, incorporating brackets that form part of the steel beams.

The PCa column 10 on the lower floor has a rectangular parallelepiped PCa concrete body 11, with multiple (ten in the illustrated example) sheath pipes 16 embedded inside, and unbonded PC steel members 17 (an example of a tension member) inserted into each sheath pipe 16. Here, the unbonded PC steel members 17 are PC steel bars, but they may also be PC steel wires or the like. Although not shown, the PCa column 10 has multiple column main reinforcement bars extending vertically, and multiple rectangular frame-shaped tie bars surrounding the outer periphery of each column main reinforcement bar.

The unbonded PC steel 17 protrudes upward from the upper end 12 of the PCa concrete body 11, and by tightening the nut 19 in a tensioned state, the anchoring plate 18 is fixed to the upper end 12 of the PCa concrete body 11, maintaining the tension of the unbonded PC steel 17.

The gap G inside the sheath tube 16 is not filled with grout, and therefore the unbonded PC steel 17 is literally in an unbonded state inside the sheath tube 16.

On the other hand, the PCa column 20 on the upper floor has a rectangular parallelepiped PCa concrete body 21, and multiple (ten in the illustrated example) sheath pipes 26 are embedded inside the PCa concrete body 21 at positions corresponding to each sheath pipe 16, and unbonded PC steel members 27 (an example of a tension member) are inserted into each sheath pipe 26. Here, the unbonded PC steel members 27 are PC steel rods. Here, the number of unbonded PC steel members 17, 27 is not limited to that shown in the illustrated example.

The upper end of unbonded PC steel 17 and the lower end of unbonded PC steel 27 are connected to each other via a mechanical joint 35 such as a coupler. Furthermore, the sheath tubes 16 and 26 are connected vertically to form a communicating sheath tube 30, and the mutually connected unbonded PC steels 17 and 27 are inserted into the communicating sheath tube 30.

Here, below the upper sheath tube 26 is an expanded sheath tube 26A with an expanded diameter, and the mechanical joint 35 is housed inside this expanded sheath tube 26A.

Although not shown in the figure, the unbonded PC steel 27 protrudes upward from the upper end of the PCa concrete body 21, and by tightening the nut while it is in a tensioned state, the anchoring plate is fixed to the upper end of the PCa concrete body 21, maintaining the tension of the unbonded PC steel 27. The sheath pipe 26 is also not filled with grout, and therefore the unbonded PC steel 27 is literally in an unbonded state inside the sheath pipe 26.

In this way, the unbonded PC steel members 17, 27 on each floor are anchored at the top ends of the corresponding PCa concrete bodies 11, 21 via anchoring plates.

A curing member 37 is installed around the anchoring plate 18 at the upper end 12 of the PCa concrete body 11, surrounding the unbonded PC steel 17 protruding upward, preventing the joint material 40 poured into the joint space 41 between the upper end 12 of the PCa column 10 and the lower end 22 of the PCa column 20 from entering the upper and lower sheath pipes 26, 16.

Here, for example, accordion joints are used as the curing members 37, and grout such as mortar is used as the joint material.

Anti-rust material 50 is applied to the joint area A of the unbonded PC steel members 17, 27, which spans the joint interface 80 of the two PCa columns 10, 20. In the illustrated example, anti-rust material 50 is also applied around the anchoring plate 18, nut 19, and mechanical joint 35, but the anti-rust material 50 may be applied only to the joint area A of the unbonded PC steel members 17, 27.

Here, the joint area A is an area within each of the PCa columns 10, 20, spanning the joint interface 80, and is, for example, a range of several centimeters to several tens of centimeters. This range is set to a range where rust is expected to occur in the unbonded PC steel members 17, 27, depending on the building's location and environment, etc.

Although not shown in the figure, anti-corrosion material 50 may be applied to the entire area of the unbonded PC steel members 17, 27.

The rust-preventive material 50 may be hot-dip galvanized, organic zinc-rich paint, or a resin-based rust-preventive material such as epoxy resin. When hot-dip galvanized is used as the rust-preventive material 50, the tendon is typically immersed in a zinc bath to apply the plating, but in this specification, such immersion and spray painting are also considered to be included in the term "application."

With the PCa joint member 100, the unbonded PC steel members 17, 27 inserted into the sheath pipes 16, 26 of the PCa columns 10, 20, respectively, are connected via mechanical joints 35, and both unbonded PC steel members 17, 27 are tensioned, eliminating the need for extended construction periods that would otherwise be required to fill the sheath pipes 16, 26 with grout.

Furthermore, by applying anti-corrosion material 50 to the joint area A of the unbonded PC steel members 17, 27, which spans the joint interface 80 of at least two PCa columns 10, 20, rusting in the joint area A of the unbonded PC steel members 17, 27 can be suppressed or prevented.

[PCa joint member according to the second embodiment]
Next, an example of a PCa joint member according to a second embodiment will be described with reference to Fig. 3. Here, Fig. 3 is a longitudinal cross-sectional view of an example of a PCa joint member according to the second embodiment, and is an enlarged view of the periphery of the joint region of PCa columns joined to each other.

PCa joint member 100A differs from PCa joint member 100 in that, instead of applying anti-corrosion material 50 to joint area A of unbonded PC steel members 17, 27, viscoelastic material 60 is disposed within joint area A of gap G between communicating sheath tube 30 and unbonded PC steel members 17, 27.

Although not shown in the figure, a viscoelastic material 60 may be disposed in the gap G throughout the entire communicating sheath tube 30.

The viscoelastic material 60 may be a viscoelastic liquid, semi-solid, or solid resin material such as rubber, as well as gum tape (registered trademark) or cellophane tape (registered trademark).

With the PCa joint member 100A, a viscoelastic material 60 is disposed in the gap G between the communicating sheath tube 30 and the unbonded PC steel members 17, 27 in the joint area A that spans the joint interface 80 of at least two PCa columns 10, 20. This reduces or prevents damage to the unbonded PC steel members 17, 27 due to collision of the unbonded PC steel members 17, 27 with the sheath tubes 16, 26 in the joint area A of at least two PCa members.

[PCa joint member according to the third embodiment]
Next, an example of a PCa joint member according to a third embodiment will be described with reference to Fig. 4. Here, Fig. 4 is a longitudinal cross-sectional view of an example of a PCa joint member according to the third embodiment, and is an enlarged view of the periphery of the joint region of PCa columns joined to each other.

PCa joint member 100B differs from PCa joint members 100 and 100A in that anti-corrosion material 50 is applied to joint area A of unbonded PC steel members 17 and 27, and further in that viscoelastic material 60 is disposed within joint area A of gap G between communicating sheath tube 30 and unbonded PC steel members 17 and 27.

With PCa joint member 100B, anti-corrosion material 50 is applied to joint area A of unbonded PC steel members 17, 27, and viscoelastic material 60 is further disposed in joint area A of gap G between communicating sheath tube 30 and unbonded PC steel members 17, 27. This prevents or prevents both rusting in joint area A of unbonded PC steel members 17, 27 and damage to unbonded PC steel members 17, 27 due to collision with sheath tubes 16, 26.

[PCa joint member according to the fourth embodiment]
Next, an example of a PCa joint member according to a fourth embodiment will be described with reference to Fig. 5. Here, Fig. 5 is a longitudinal cross-sectional view of an example of a PCa joint member according to the fourth embodiment, and is an enlarged view of the periphery of the joint region of PCa columns joined to each other.

Compared to PCa joint member 100B, PCa joint member 100C further comprises a stiffener 70 that straddles the joint interface 80 of PCa columns 10, 20 and surrounds their outer peripheries (side surfaces 13, 23). However, instead of PCa joint member 100B, PCa joint members 100, 100A may also be provided with a stiffener 70.

The stiffener 70 is fixed to the PCa columns 10, 20 with bolts 75.

The stiffener 70 shown in the figure is a steel plate or carbon fiber sheet, but other structures such as a frame structure made of multiple steel sections, steel pipes, square pipes, etc. may also be used.

PCa joint member 100C not only prevents rusting and breakage in joint area A of unbonded PCa steel members 17, 27, but also prevents concrete peeling in the cover of PCa columns 10, 20 by surrounding the outer periphery of PCa columns 10, 20 in joint area A with stiffener 70. Furthermore, stiffener 70 prevents outside air, rainwater, etc. from penetrating into joint interface 80, which also makes it possible to prevent rusting of unbonded PCa steel members 17, 27.

Other embodiments may be possible in which other components are combined with the configurations described in the above embodiments, and the present invention is in no way limited to the configurations shown here. In this regard, changes can be made without departing from the spirit of the present invention, and can be determined appropriately depending on the application form.

10: PCa column (lower floor PCa column, PCa member, PCaPC column)
11: PCa concrete body 12: Top end 13: Side 16: Sheath pipe 17: Unbonded PC steel (tension member)
18: Fixing plate 19: Nut 20: PCa column (upper floor PCa column, PCa member, PCaPC column)
21: PCa concrete body 22: Lower end 23: Side 26: Sheath pipe 26A: Widened sheath pipe 27: Unbonded PC steel (tension member)
30: Communicating sheath pipe 35: Mechanical joint 37: Covering member (bellows joint)
40: Joint material 41: Joint space 50: Rust prevention material 60: Viscoelastic material 70: Stiffening material (steel plate)
75: Bolt 80: Joint interface 100, 100A, 100B, 100C: PCa joint member (PCaPC joint member)
A: Joint area G: Gap

Claims (9)

A PCa joint member in which PCa members made of precast concrete and having a plurality of sheath pipes are joined to each other while communicating the corresponding sheath pipes to form a communicating sheath pipe,
Tendons are inserted into all of the communicating sheath tubes, and the tendons are tensioned in an unbonded state via mechanical joints having a predetermined length in the extension direction of the tendons ,
A PCa joint member characterized in that a rust-preventive material is applied to a joint region of the tendon that spans the joint interface between the two PCa members and has a predetermined length that is longer than the predetermined length in the extension direction of the tendon . A PCa joint member in which PCa members made of precast concrete and having a plurality of sheath pipes are joined to each other while communicating the corresponding sheath pipes to form a communicating sheath pipe,
Tendons are inserted into all of the communicating sheath tubes, and the tendons are tensioned in an unbonded state via mechanical joints having a predetermined length in the extension direction of the tendons ,
A PCa joint member characterized in that a viscoelastic material is arranged in a joint region of the gap between the communicating sheath tube and the tension member that spans the joint interface of the two PCa members and has a predetermined length that is longer than the predetermined length in the extension direction of the tension member . A PCa joint member in which PCa members made of precast concrete and having a plurality of sheath pipes are joined to each other while communicating the corresponding sheath pipes to form a communicating sheath pipe,
Tendons are inserted into all of the communicating sheath tubes, and the tendons are tensioned in an unbonded state via mechanical joints having a predetermined length in the extension direction of the tendons ;
a rust preventative material is applied to a joint region of the tendon that spans the joint interface between the two PCa members and has a predetermined length that is longer than the predetermined length in the extension direction of the tendon ;
A PCa joint member characterized in that a viscoelastic material is arranged in the joint region of the gap between the communicating sheath tube and the tension member , spanning the joint interface between the two PCa members. A PCa joint member according to any one of claims 1 to 3, further comprising a stiffener spanning the joint interface between the two PCa members and surrounding their outer peripheries. A PCa joint member according to any one of claims 1, 3, and claim 4 depending on claims 1 and 3, characterized in that the anti-corrosion material is applied to the entire area of the tendon inserted into the communicating sheath tube. A PCa joint member according to any one of claims 2, 3, and claim 4 dependent on claims 2 and 3, characterized in that the viscoelastic material is disposed in gaps throughout the entire area of the communicating sheath tube. The PCa joint member described in any one of claims 1 to 6, characterized in that the PCa members to be joined together are PCa columns. The PCa joint member described in any one of claims 1 to 6, characterized in that the PCa members to be joined together are a PCa column and a PCa joint. The PCa joint member described in any one of claims 1 to 6, characterized in that the PCa members to be joined together are PCa beams.