PCa joint member

Abstract

To provide a PCa joint member which has PCa members connected to each other via tendons in an unbonded state, capable of inhibiting or suppressing a failure in the integration of the PCa joint member resulting from the breakage of all tendons due to the rust development or the collision with sheath pipes.SOLUTION: A PCa joint member 100 has PCa members 10, 20 including a plurality of precast-concrete sheath pipes 16, 26 and joined to each other while allowing the communication of the corresponding sheath pipes 16, 26 therewith to form a communication sheath pipe 30. Tendons 17, 27 inserted into part of the communication sheath pipe 30 are strained in a bonded state, and the tendons 17, 27 inserted into the remaining communication sheath pipe 30 are strained in an unbonded state.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a PCa joint member.

Background Art

[0002] For example, when constructing the column joints between columns on the upper and lower floors of an RC (Reinforced Concrete) structure, the column-beam joints between an RC column and a beam, the column-beam joints of a hybrid structure of an RC column and an S (Steel) beam, etc. by casting concrete on site, the extension of the construction period is an issue, and this issue becomes more prominent in the case of high-rise buildings. Therefore, both the columns on the upper and lower floors or the columns and joints are made of precast concrete (hereinafter, appropriately referred to as "PCa"), and the PCa columns and PCa joints (both are included in the PCa members) are transported to the site and assembled into PCa joint members, so that a construction method of achieving integration with only a minimum amount of grout filling may be applied. According to this construction method of PCa joint members, the construction period can be significantly shortened, including for high-rise buildings. Moreover, since the columns and column-beam joints continuous between the upper and lower floors are formed by PCa members, it becomes possible to construct a building with high structural reliability. Among the construction methods of PCa joint members, by tensioning PCa members with tensioning members such as PC (Prestressed Concrete) steel bars and PC steel wires and tightening them against each other to construct a precast prestressed concrete (hereinafter, appropriately referred to as "PCaPC") joint member, a further shortening of the construction period can be achieved. In this specification, the PCaPC joint member is included in the PCa joint member, and the PCaPC member as its component member is included in the PCa member.

[0003] The above-mentioned PCa members are provided with a plurality of sheath tubes inside. The PCa members to be joined to each other form a communicating sheath tube by communicating the corresponding sheath tubes of both sides, and after a tension member is inserted into the communicating sheath tube and tensioned, the communicating sheath tube is filled with grout so that the tension member is in a bonded state. Generally, the connection between the PCa members is achieved by a plurality of tensioned bonded tension members. However, the operation of filling the communicating sheath tube with grout is time-consuming, and this problem becomes more prominent due to an increase in the number of communicating sheath tubes and an increase in the number of grout filling locations due to the high-rise of buildings. Furthermore, there is also a problem that the curing period until the grout filled in the communicating sheath tube exhibits a predetermined strength can significantly affect the prolongation of the construction period.

[0004] Here, Patent Document 1 proposes a high-rise building provided with precast prestressed concrete columns. This high-rise building is a high-rise building including a plurality of precast prestressed concrete columns in which tension members are inserted vertically into concrete column bodies and a plurality of vibration control devices for suppressing the sway of the building. In the precast prestressed concrete column, the tension member is arranged in the concrete column body in an unbonded state, and the vibration control device suppresses the sway of the high-rise building so that the deformation of the tension member due to the sway of the high-rise building is within the elastic range of the tension member.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] According to the high-rise building described in Patent Document 1, by applying a tendon in an unbonded state, the above problems during grout filling can be solved. By the way, in the form where the tendon is tensioned in an unbonded state inside the sheath pipe, since the tendon is not protected by grout, rusting of the tendon in, for example, the joint region of the PCa member can be a problem. Also, during the deformation of the building during an earthquake, there is a risk that the tendon may collide with the sheath pipe, for example, in the above joint region. And due to rusting and collision in these joint regions, the tendon may be damaged, and if all the tendons are damaged, for example, in the joint region, it may lead to the loss of integrity of the PCa joint member.

[0007] The present invention has been made in view of the above problems, and in a PCa joint member in which PCa members are joined by tendons in an unbonded state, an object of the present invention is to provide a PCa joint member capable of suppressing or preventing all the tendons from being damaged due to rusting or collision with the sheath pipe and the loss of integrity of the PCa joint member.

Means for Solving the Problems

[0008] 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 forming a communicating sheath pipe by communicating the corresponding sheath pipes, wherein the tendons inserted into some of the communicating sheath pipes are in a tensioned bonded state, and the tendons inserted into the remaining communicating sheath pipes are in a tensioned unbonded state.

[0009] According to this aspect, among a plurality of communicating sheath tubes formed by the sheath tubes provided in the PCa members joined to each other, the tension members inserted into some of the communicating sheath tubes are in a tensioned bonded state, and the tension members inserted into the remaining communicating sheath tubes are in a tensioned unbonded state. As a result, even when the unbonded tension members are damaged due to rusting or collision with the sheath tubes, rusting and collision do not occur in the bonded tension members, so the damage is eliminated, and the loss of integrity of the PCa joining member can be avoided by the non-damaged bonded tension members.

[0010] Here, the "tensioned bonded state" includes a form in which the entire area of the tension member inserted into the communicating sheath tube is tensioned in a bonded state (the tension member in this form becomes a bonded tension member), or a form in which, for example, only the joining region of the PCa member is tensioned in a bonded state (a form in which only a part of the unbonded tension member is in a bonded state). On the other hand, the "tensioned unbonded state" is a form in which the entire area of the tension member inserted into the communicating sheath tube is tensioned in an unbonded state. As described above, the PCa joining member of this aspect includes a PCaPC joining 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.

[0011] Further, another aspect of the PCa joining member according to the present invention is Among the plurality of the communicating sheath tubes, the tension member inserted into the communicating sheath tube located at the center or substantially at the center in a cross section perpendicular to the axial direction of the PCa member is in a bonded state.

[0012] According to this aspect, since the tendon inserted into the communication sheath tube located at the center or substantially the center in the cross-section of the PCa member is in a bonded state, a bending moment does not act or hardly acts on the tendon in this bonded state. Therefore, the load-bearing capacity of the tendon in the bonded state can be maintained. Even if the number of tendons in the bonded state is small, it is possible to maintain the integrity of the PCa joint member with the tendon in this bonded state. For example, in a form where an odd number of tendons are provided laterally, one tendon in the center can be set. In a form where an even number of tendons are provided laterally, two tendons in the center or either one of the two tendons in the center becomes the tendon located substantially in the center.

[0013] Another aspect of the PCa joint member according to the present invention is Characterized in that grout is injected into a joint region straddling at least two joint interfaces of the PCa members in a gap between the communication sheath tube and the tendon to form the bonded state.

[0014] According to this aspect, since grout is injected into a joint region straddling at least two joint interfaces of the PCa members in a gap between the communication sheath tube and the tendon to form a bonded state, it is possible to form the bonded state of some tendons with an amount of grout as small as possible.

[0015] Here, the "joint region straddling the joint interface" means a region in the interior of both PCa members straddling the joint interface, for example, in the range of about several centimeters to several tens of centimeters. It is reasonable to identify the range where rust may occur from the joint interface, identify the range where the tendon collides with the sheath tube during building deformation, and set the larger range among the identified ranges as the "joint region straddling the joint interface". At this time, the range where rust may occur from the joint interface is set according to the site environment of the building, etc.

[0016] Another aspect of the PCa joint member according to the present invention is Characterized in that the grout is injected into the entire area of the communication sheath tube to form the bonded state.

[0017] According to this aspect, since the grout is injected into the entire area of the communication sheath pipe to form a bonded state, it is possible to suppress or prevent rusting in the entire area of the prestressing tendon in the bonded state and damage caused by collision with the sheath pipe.

[0018] Also, another aspect of the PCa joint member according to the present invention is further comprising a supplementary stiffening member that surrounds the outer peripheries of the two PCa members across the joint interface therebetween.

[0019] According to this aspect, by further comprising a supplementary stiffening member that surrounds the outer peripheries of the PCa members across the joint interface, the supplementary stiffening member can prevent the concrete of the overlapping portion of the PCa member in the joint region from peeling off. Further, by the supplementary stiffening member surrounding the outer periphery of the joint region, it is possible to suppress the intrusion of outside air, rainwater, etc. into the interface, and this can also suppress the rusting of the prestressing tendon.

[0020] Also, 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.

[0021] According to this aspect, since the PCa members to be joined to each other are both PCa columns, it is possible to suppress or prevent all the prestressing tendons provided in the vertically continuous PCa columns from being damaged by rusting or collision with the sheath pipe and the integrity of the PCa joint member from being lost.

[0022] Also, 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 openings.

[0023] According to this aspect, since the PCa members to be joined to each other are PCa columns and PCa openings, it is possible to suppress or prevent all the prestressing tendons provided in the column-beam joint from being damaged by rusting or collision with the sheath pipe and the integrity of the PCa joint member from being lost.

[0024] Also, in another aspect of the PCa joining member according to the present invention, the PCa members to be joined to each other are characterized by being PCa beams.

[0025] According to this aspect, since all the tendons provided in the laterally continuous PCa beams are damaged by rusting or collision with the sheath pipe, and the integrity of the PCa joining member is lost, it is possible to suppress or prevent this by the fact that all the PCa members to be joined to each other are PCa beams.

Advantages of the Invention

[0026] As can be understood from the above description, according to the PCa joining member of the present invention, in the PCa joining member in which the PCa members are connected by the unbonded tendons, it is possible to suppress or prevent all the tendons from being damaged by rusting or collision with the sheath pipe and the integrity of the PCa joining member from being lost.

Brief Description of the Drawings

[0027]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0028] Hereinafter, an example of the PCa joint member according to each embodiment will be described with reference to the accompanying drawings. In the present specification and drawings, substantially the same components may be denoted by the same reference numerals, and redundant descriptions may be omitted.

[0029] [PCa Joint Member According to the First Embodiment] First, with reference to FIGS. 1 and 2, an example of the PCa joint member according to the first embodiment will be described. Here, FIG. 1 is a longitudinal sectional view of an example of the PCa joint member according to the first embodiment, and is an enlarged view of the periphery of the joint region of the PCa columns to be joined to each other, and FIG. 2 is a view taken along the line II-II of FIG. 1.

[0030] The PCa joint member (PCa-PC joint member) 100 is formed by joining the lower PCa column (PCa-PC column) 10 (an example of a PCa member (PCa-PC member)) and the upper PCa column (PCa-PC column) 20 (an example of a PCa member (PCa-PC member)) to each other. Here, although not shown, in addition to the illustrated example, the PCa joint member includes a joint member between a PCa column (PCa-PC column) and a PCa joint, and a joint member between a PCa beam (PCa-PC beam) and a PCa beam (PCa-PC beam). With these various PCa joint members, a hybrid structure constituting a multi-story building is formed.

[0031] Here, the "hybrid structure" is a structure including PCa columns 10 and 20, which are precast RC (Reinforced Concrete) columns, a PCa joint (not shown), which is also a precast RC joint, and a steel frame beam (not shown) connecting the PCa joints. Specifically, the PCa joint can be said to be of SRC (Steel Reinforced Concrete) construction, incorporating brackets that form part of the steel frame beam.

[0032] The lower PCa column 10 has a rectangular parallelepiped-shaped PCa concrete body 11. Inside the PCa concrete body 11, a plurality (ten in the illustrated example) of sheath pipes 16 are embedded, and an unbonded PC steel material 17 (an example of a tendon) is inserted into each sheath pipe 16. Here, the unbonded PC steel material 17 is a PC steel bar, but it may also be a PC steel wire or the like. Although not shown in the figure, the PCa column 10 has a plurality of column main reinforcements extending in the vertical direction and a plurality of rectangular frame-shaped stirrups surrounding the outer periphery of each column main reinforcement.

[0033] The unbonded PC steel material 17 protrudes upward from the upper end 12 of the PCa concrete body 11. By tightening the nut 19 in the tensioned state, the fixing plate 18 is fixed to the upper end 12 of the PCa concrete body 11, and the tensioned state of the unbonded PC steel material 17 is maintained.

[0034] The gap G inside the sheath pipe 16 is not filled with grout. Therefore, the unbonded PC steel material 17 is in an unbonded state inside the sheath pipe 16 literally.

[0035] On the other hand, the upper PCa column 20 has a rectangular parallelepiped-shaped PCa concrete body 21. At positions corresponding to each sheath pipe 16 inside the PCa concrete body 21, a plurality (ten in the illustrated example) of sheath pipes 26 are embedded, and an unbonded PC steel material 27 (an example of a tendon) is inserted into each sheath pipe 26. Here, the unbonded PC steel material 27 is a PC steel bar.

[0036] The upper end of the unbonded PC steel material 17 and the lower end of the unbonded PC steel material 27 are connected to each other via a mechanical joint 35 such as a coupler. Further, by the sheath pipes 16 and 26 communicating vertically, a communicating sheath pipe 30 is formed, and the connected unbonded PC steel materials 17 and 27 are inserted into the communicating sheath pipe 30.

[0037] Here, the lower part of the upper sheath pipe 26 is an expanded-width sheath pipe 26A with an expanded pipe diameter, and the mechanical joint 35 is accommodated inside this expanded-width sheath pipe 26A.

[0038] Although illustration is omitted, the unbonded PC steel material 27 protrudes upward from the upper end of the PCa concrete body 21. By tightening the nut in a tensioned state, the fixing plate is fixed to the upper end of the PCa concrete body 21, and the tensioned state of the unbonded PC steel material 27 is maintained. The sheath pipe 26 is not filled with grout either. Therefore, the unbonded PC steel material 27 is in an unbonded state inside the sheath pipe 26 literally.

[0039] In this way, the unbonded PC steel materials 17 and 27 on each floor are fixed via the fixing plate at the upper ends of the corresponding PCa concrete bodies 11 and 21.

[0040] Around the fixing plate 18 at the upper end 12 of the PCa concrete body 11, a curing member 37 that surrounds the unbonded PC steel material 17 protruding upward is installed, and the joint material 40 placed in the joint space 41 between the upper end 12 of the PCa column 10 and the lower end 22 of the PCa column 20 is prevented from entering the upper and lower sheath pipes 26 and 16.

[0041] Here, for example, a jabara joint is applied to the curing member 37, and grout such as mortar is applied to the joint material.

[0042] As shown in FIG. 2, among the unbonded PC steel materials 17, five in each row in two rows, the joint region A straddling the joint interface 80 of the unbonded PC steel material 17 located in the center is in a bonded state by the grout 50 filled inside the sheath pipes 16 and 26. Here, the number of the unbonded PC steel materials 17 and 27 is not limited to the illustrated example, and the number of the unbonded PC steel materials 17 and 27 located in the center is also not limited to the illustrated example.

[0043] Here, the joint region A is a region within the interiors of both PCa columns 10 and 20 across the joint interface 80, for example, in the range of several centimeters to several tens of centimeters. This range is determined by identifying the range where rusting may occur from the joint interface 80 and the range where the unbonded PC steel materials 17 and 27 collide with the sheath pipes 16 and 26 during building deformation, and is set to the larger of the identified ranges. Also, the rusting range is set according to the building's site environment and the like.

[0044] According to the PCa joint member 100, the unbonded PC steel materials 17 and 27 respectively inserted into the sheath pipes 16 and 26 of the PCa columns 10 and 20 are connected via the mechanical joint 35, and since both unbonded PC steel materials 17 and 27 are tensioned, it is possible to eliminate the lengthening of the construction period that depends on filling the entire area of all sheath pipes 16 and 26 with grout.

[0045] Also, grout 50 is injected into the joint region A across the joint interface 80 of at least two PCa columns 10 and 20 among the gaps G between the communication sheath pipe 30 and the unbonded PC steel materials 17 and 27 to form a bonded state, so that it is possible to form a bonded state of some of the unbonded PC steel materials 17 and 27 with a minimally small amount of grout. And, since the joint region A of two of the total ten continuous unbonded PC steel materials 17 and 27 is in a bonded state, even if the remaining eight unbonded PC steel materials 17 and 27 are damaged due to rusting or collision with the sheath pipe 16, the two unbonded PC steel materials 17 and 27 in the bonded state will not rust or collide, so the damage is eliminated, and it is possible to avoid the loss of integrity of the PCa joint member 100 by the two unbonded PC steel materials 17 and 27 in the non-damaged bonded state.

[0046] Furthermore, since a part of the unbonded PC steel materials 17 and 27 inserted into the communication sheath pipe 30 located at the center in the cross-section of the PCa members 10 and 20 is in a bonded state, a bending moment does not act or hardly acts on the unbonded PC steel materials 17 and 27 that partly include this bonded state. Therefore, the load-bearing capacity of the two unbonded PC steel materials 17 and 27 can be maintained, and the integrity of the PCa joint member 100 can be retained by these two unbonded PC steel materials 17 and 27.

[0047] [PCa Joint Member According to the Second Embodiment] Next, with reference to FIG. 3, an example of a PCa joint member according to the second embodiment will be described. Here, FIG. 3 is a longitudinal 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 the PCa columns joined to each other.

[0048] The PCa joint member 100A is different from the PCa joint member 100 in that the entire gap G between the tendons 17A and 27A located at the center and the sheath pipes 16 and 26 is filled with grout 50, and bonded PC steel materials 17A and 27A are formed. That is, the two tendons located at the center are the bonded PC steel materials 17A and 27A, and the remaining eight tendons are the unbonded PC steel materials 17 and 27.

[0049] According to the PCa joint member 100A, since the tendons 17A and 27A located at the center are the bonded PC steel materials, in addition to achieving the same effect as the PCa joint member 100, rusting over the entire area of the bonded PC steel materials 17A and 27A located at the center and damage due to collision with the sheath pipe can be suppressed or prevented.

[0050] [PCa Joint Member According to the Third Embodiment] Next, with reference to FIG. 4, an example of a PCa joint member according to the third embodiment will be described. Here, FIG. 4 is a longitudinal 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 the PCa columns joined to each other.

[0051] The PCa joint member 100B further includes a supplementary stiffening member 70 that surrounds the outer peripheries (side surfaces 13 and 23) of the PCa columns 10 and 20 across the joint interface 80 with respect to the PCa joint member 100. Here, instead of the PCa joint member 100, a form in which the PCa joint member 100A further includes the supplementary stiffening member 70 may be adopted.

[0052] The supplementary stiffening member 70 is fixed to the PCa columns 10 and 20 by bolts 75.

[0053] The illustrated supplementary stiffening member 70 is a steel plate or a carbon fiber sheet. However, other frame structures made of a plurality of shaped steel materials, steel pipes, angle pipes, etc. may also be applied.

[0054] According to the PCa joint member 100B, in addition to suppressing rusting and damage in the joint region A of the unbonded PC steel materials 17 and 27, since the supplementary stiffening member 70 surrounds the outer peripheries of the PCa columns 10 and 20 in the joint region A, it is possible to prevent the concrete in the covering portions of the PCa columns 10 and 20 from peeling off. Furthermore, the supplementary stiffening member 70 can suppress the intrusion of outside air, rainwater, etc. into the joint interface 80, and this can also suppress the rusting of the unbonded PC steel materials 17 and 27.

[0055] Other embodiments in which other components are combined with the configurations described in the above embodiments may be possible, and the present invention is not limited to the configurations shown here. In this regard, it can be changed without departing from the gist of the present invention and can be appropriately determined according to the application form.

Explanation of Reference Numerals

[0056] 10: PCa column (lower - floor PCa column, PCa member, PCaPC column) 11: PCa concrete body 12: Upper end 13: Side surface 16: Sheath pipe 17: Unbonded PC steel material (tension member) 17A: Bonded PC steel material (tension member) 18: Fixing plate 19: Nut 20: PCa column (PCa column on the upper floor, PCa member, PCaPC column) 21: PCa concrete body 22: Lower end 23: Side surface 26: Sheath pipe 26A: Widened sheath pipe 27: Unbonded PC steel material (tension member) 27A: Bonded PC steel material (tension member) 30: Communicating sheath pipe 35: Mechanical joint 37: Curing member (Jabara joint) 40: Joint material 41: Joint space 50: Grout 70: Stiffening member (steel plate) 75: Bolt 80: Joint interface 100, 100A, 100B: PCa joint member (PCaPC joint member) A: Joint area G: Gap

Claims

1. A PCA joining member in which PCA members made of precast concrete and provided with a plurality of sheath pipes are joined to each other while forming a communicating sheath pipe by communicating the corresponding sheath pipes, wherein the tendons inserted into some of the communicating sheath pipes are in a tensioned bonded state, the tendons inserted into the remaining communicating sheath pipes are in a tensioned unbonded state, characterized in that it is a PCA joining member.

2. The PCA joining member according to claim 1, wherein the tendon inserted into the communicating sheath pipe located at the center or substantially at the center in a cross section orthogonal to the axial direction of the PCA member among the plurality of communicating sheath pipes is in a bonded state.

3. The PCA joining member according to claim 1 or 2, wherein grout is injected into a joining region straddling the joining interfaces of at least two of the PCA members among the gaps between the communicating sheath pipes and the tendons to form the bonded state.

4. The PCA joining member according to claim 3, wherein the grout is injected throughout the communicating sheath pipe to form the bonded state.

5. The PCA joining member according to any one of claims 1 to 4, further comprising a stiffening member surrounding the outer circumferences of two of the PCA members across the joining interface therebetween.

6. The PCA joining member according to any one of claims 1 to 5, wherein the PCA members joined to each other are PCA columns and PCA columns.

7. The PCA joining member according to any one of claims 1 to 5, wherein the PCA members joined to each other are a PCA column and a PCA joint.

8. The PCA joining member according to any one of claims 1 to 5, wherein the PCA members joined to each other are PCA beams and PCA beams.

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