PCa joints and their construction methods

Abstract

To provide a PCa joined body capable of eliminating a prolonged construction period due to filling of grout into a sheath pipe, and eliminating the need of repair and supplemental treatment caused by measures to maintain a standing posture of the PCa column, and a construction method thereof.SOLUTION: In a PCa joined body 50 in which a PCa column 10 and a PCa joint 20 are joined, the PCa joint 20 is arranged above the PCa column 10, a first unbonded PC steel 17 and a second unbonded PC steel 27 inserted into a first sheath pipe 16 and a second sheath pipe 26 are connected via a mechanical joint 35, and they are final tensioned, a first fixing plate 18 to which a first unbonded PC steel 17 is fixed is arranged at a first joint 41 between the PCa column 10 and the PCa joint 20, a second fixing plate 28 to which the second unbonded PC steel 27 is fixed is arranged above the PCa joint 20, and above and below the PCa joint 20, an endless steel band plate 24 extending in the circumferential direction of the PCa joint is provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a PCa joint and a construction method thereof. [Background technology]

[0002] For example, when using on-site concrete pouring to construct column-to-beam joints in reinforced concrete (RC) structures or hybrid column-to-beam joints between RC columns and steel beams, construction time can be lengthened. This issue is particularly pronounced in high-rise buildings. To address this issue, a connection method is sometimes used in which the upper and lower columns and the joints connecting them are both made of precast concrete (hereafter referred to as "PCa"). The PCa columns and PCa joints (both included in PCa components) are transported to the site and assembled to form a PCa joint, achieving integration with minimal grouting. This PCa joint construction method significantly shortens construction time, including for high-rise buildings, and, because the column-beam joints are formed using PCa components, enables the construction of buildings with high structural reliability. Among the methods for constructing PCa joints, precast prestressed concrete (hereinafter referred to as "PCaPC") joints can be constructed by tensioning PCa members with tendons such as PC (Prestressed Concrete) steel bars or PC steel wires and fastening them together, thereby further shortening the construction period. In this specification, PCaPC joints are considered to be included in PCa joints, and their constituent PCaPC members are considered to be included in PCa members.

[0003] Patent Document 1 proposes a joint structure for a precast prestressed reinforced concrete frame in which a sheath tube for reinforcing bars is buried in advance in the joint between a column and a beam made of precast prestressed concrete members, a predetermined amount of reinforcing bars is housed in the sheath tube for reinforcing bars simultaneously with or after joining the column and beam, the joint is fixed by tensioning the PC steel, and the reinforcing bars are fixed and held in the sheath tube for reinforcing bars so that the PC steel and the reinforcing bars control the dispersion of cracks that occur at the joint. The PC cable, which is the PC steel, is inserted into a metal sheath tube buried inside the column and beam, and grout is filled into the sheath tube after tensioning the PC cable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 9-105173 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional PCa joints (PCaPC joints) in which PCa members are joined together, such as those described in Patent Document 1, the tendons inserted into the sheath pipes of the PCa members are tensioned, and then the sheath pipes are filled with grout to bond the tendons and construct the PCa joint. As a result, grout filling is required every time a PCa joint is constructed on each floor, which poses a problem of lengthening the construction period.

[0006] Furthermore, when constructing PCa columns in reinforced concrete structures, for example, bracing members are attached to the sides of the PCa columns, and one end of the bracing member is fixed to a jig installed on the slab, in order to maintain the upright position of the PCa columns until the cross members are installed. Therefore, after the PCa columns are made to stand on their own, the bracing members must be removed and the jig removed from the slab. When removing these jigs, the concrete around the jig that holds the jig in place must be chipped off, and the chipped areas must then be repaired, a process known as "damage treatment." This labor-intensive process also poses an issue.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a PCa joint in which a PCa column is joined to a PCa joint equipped with a steel beam, which can eliminate the lengthening of construction time that is caused by filling grout into the sheath pipe, and which can eliminate the need for damage treatment that occurs due to measures to maintain the upright position of the PCa column, and a construction method for the same. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the PCa joint body according to the present invention is: A PCa joint in which a PCa column made of precast concrete and equipped with a first sheath pipe is joined to a PCa joint made of precast concrete and equipped with a second sheath pipe and a steel beam, The PCa joint is disposed above the PCa column, and the first unbonded PC steel and the second unbonded PC steel, which are respectively inserted into the first sheath pipe and the second sheath pipe that are interconnected, are connected via a mechanical joint, and the first unbonded PC steel and the second unbonded PC steel are fully tensioned, A first fixing plate to which the first unbonded PC steel member is fixed is disposed in a first joint between the PCa column and the PCa connection, A second fixing plate to which the second unbonded PC steel member is fixed is disposed above the PCa joint, The PCa joint is characterized in that endless steel band plates extending circumferentially around the PCa joint are provided above and below the joint, and the steel beam extends laterally from between the upper and lower band plates.

[0009] According to this embodiment, the first unbonded PC steel and the second unbonded PC steel, which are inserted into the first sheath pipe of the PCa column and the second sheath pipe of the PCa joint, respectively, are connected via a mechanical joint, and both unbonded PC steels are fully tensioned, thereby eliminating the need for a longer construction period due to the need to fill the sheath pipes with grout.

[0010] Here, the planar shape of the PCa joint is, for example, rectangular (rectangular or square), and there are forms in which the steel beams protrude laterally from four sides, as well as forms in which the steel beams protrude laterally from one to three sides. Furthermore, by providing endless steel band plates extending circumferentially above and below the PCa joint, the stress transfer performance from the steel beams to the PCa joint and PCa column can be improved, thereby enhancing the seismic performance of buildings equipped with PCa joints. As mentioned above, the PCa joint of this embodiment includes a PCaPC joint, the PCa joint includes a PCaPC joint, and the PCa column includes a PCaPC column.

[0011] In another embodiment of the PCa joint body according to the present invention, The first unbonded PC steel member is characterized in that it is pre-tensioned and then fully tensioned.

[0012] According to this embodiment, the first unbonded PC steel is provisionally tensioned and then fully tensioned, so that during the construction process, the PCa column can be made to stand on its own by provisionally tensioning the first unbonded PC steel, thereby eliminating the need for damage treatment that occurs when conventional measures are taken to maintain the upright position of the PCa column, i.e., attaching a support member to the side of the PCa column and fixing one end of the support member to a jig installed on the slab.

[0013] In addition, one aspect of the construction method for PCa joint bodies according to the present invention is as follows: A method for constructing a PCa joint by joining a PCa column made of precast concrete and having a first sheath pipe to a PCa joint made of precast concrete and having a second sheath pipe and a steel beam, Step A includes temporarily tensioning a first unbonded prestressing steel member that is inserted into the first sheath pipe of the PCa column and protruding upward, and fixing the first unbonded prestressing steel member with a first fixing plate disposed in a first joint space above the PCa column, thereby making the PCa column self-supporting; The method is characterized by having a step B in which a second unbonded PC steel member that is inserted into the second sheath pipe of the PCa joint and protrudes downward is connected to the first unbonded PC steel member that protrudes upward via a mechanical joint, the second unbonded PC steel member and the first unbonded PC steel member are fully tensioned, and the second unbonded PC steel member is fixed with a second fixing plate arranged in a second joint space above the PCa joint.

[0014] According to this aspect, in step B, the first unbonded prestressing tendon and the second unbonded prestressing tendon inserted into the first sheath pipe of the PCa column and the second sheath pipe of the PCa connection, respectively, are connected via a mechanical joint, and both unbonded prestressing tendons are fully tensioned, thereby eliminating the need for a longer construction period that would otherwise be required to fill the sheath pipes with grout. Furthermore, in step A, the first unbonded prestressing tendon of the PCa column is temporarily tensioned to make it self-standing, eliminating the need for the damage treatment that occurs when applying conventional measures to maintain the upright position of the PCa column.

[0015] In another aspect of the construction method for PCa joint bodies according to the present invention, In the step B, curing is performed in the first joint space to prevent the joint material from entering the first sheath pipe and the second sheath pipe that communicate with the first joint space, the joint material is poured into the first joint space, and the main tensioning is performed after the joint material has hardened.

[0016] According to this aspect, in the first joint space between the PCa column and the PCa connection, by curing the first and second sheath pipes that communicate with the first joint space to prevent the joint material from entering them, and then pouring the joint material into the first joint space, it is possible to construct the joint in the first joint space while maintaining the unbonded state of the tendons inside the sheath pipes. Here, the joint material can be grout such as mortar.

[0017] In another aspect of the construction method for PCa joint bodies according to the present invention, The method is characterized in that the PCa joint body corresponding to two or more stories is constructed by repeating the steps A and B.

[0018] According to this embodiment, by repeating steps A and B to construct PCa joints corresponding to two or more floors, the construction period can be shortened for each floor, making the benefits of shortening the construction period even more pronounced when constructing high-rise buildings or super-tall buildings over 100m in height.

[0019] In another aspect of the construction method for PCa joint bodies according to the present invention, An endless steel band plate extending in the circumferential direction of the PCa joint is provided above and below the PCa joint, The steel beams extend laterally from between the upper and lower band plates.

[0020] According to this embodiment, since the PCa joint is equipped with a band plate, a PCa joint having excellent stress transmission performance from the steel beam to the PCa joint and PCa column can be constructed. [Effects of the Invention]

[0021] As can be understood from the above explanation, the PCa joint and its construction method of the present invention can eliminate the lengthening of construction time that is caused by filling grout into the sheath pipe, and can eliminate the need for damage treatment that occurs when taking measures to maintain the upright position of the PCa column. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 2 is an exploded perspective view of an example of a PCa joined body according to an embodiment, in which the inside of the PCa joint can be seen. [Figure 2] FIG. 1 is a perspective view of an example of a PCa bonded body according to an embodiment. [Figure 3] FIG. 10 is a perspective view of another example of a PCa joint, allowing the interior to be seen. [Figure 4] 1 is a perspective view of an example of a hybrid frame including a PCa joint body according to an embodiment. [Figure 5] FIG. 2 is a process diagram of an example of a construction method for a PCa joint body according to an embodiment. [Figure 6] 5A to 5C are process diagrams illustrating an example of a construction method for a PCa joint body according to an embodiment. [Figure 7] 6A to 6C are process diagrams illustrating an example of a construction method for a PCa joint body according to an embodiment. [Figure 8] 7A to 7C are process diagrams illustrating an example of a construction method for a PCa joint body according to an embodiment. [Figure 9] 8A to 8C are process diagrams illustrating an example of a construction method for a PCa joint body according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an example of a PCa joint assembly and a construction method thereof according to an embodiment will be described 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 explanation.

[0024] [PCa joint body according to the embodiment] First, an example of a PCa joined body according to an embodiment and an example of a PCa frame including the PCa joined body will be described with reference to Figures 1 to 4. Here, Figure 1 is an exploded perspective view of an example of a PCa joined body according to an embodiment, in which the interior of the PCa joint is visible, and Figure 2 is a perspective view of an example of a PCa joined body according to an embodiment. Also, Figure 3 is a perspective view of another example of a PCa joint, in which the interior is visible. Furthermore, Figure 4 is a perspective view of an example of a hybrid frame including a PCa joined body according to an embodiment.

[0025] A PCa joint (PCaPC joint) 50 is formed by interconnecting PCa columns (PCaPC columns) 10 and PCa joints (PCaPC joints) 20. For example, as shown in FIG. 4, the frame of each floor of a building is formed by arranging multiple PCa joints 50 side by side and connecting each PCa joint 50 with a steel beam 60, and the frames of each floor are stacked one above the other to form a hybrid frame 100. Here, the "hybrid frame" is a structure including PCa columns 10, which are columns made of precast reinforced concrete (RC), PCa joints 20, which are also precast reinforced concrete joints, and steel beams 60 that connect the PCa joints 20 together. More specifically, the PCa joints 20 can also be considered to be made of steel reinforced concrete (SRC), incorporating brackets 22 that form part of the steel beams.

[0026] Returning to Figure 1, the PCa column 10 has a rectangular parallelepiped PCa concrete body 11, with multiple (four in the illustrated example) first sheath pipes 16 buried inside the PCa concrete body 11, and a first unbonded PC steel member 17 inserted into each first sheath pipe 16. Here, the first unbonded PC steel member 17 is a PC steel rod, but it may also be a PC steel wire or the like. Here, although not shown, the PCa column 10 has multiple assembly reinforcements extending in the vertical direction and multiple rectangular frame-shaped hoops surrounding the outer periphery of each assembly reinforcement.

[0027] The first unbonded PC tendon 17 protrudes upward from the upper end 11a of the PCa concrete body 11, and by tightening the nuts 19 in the fully tensioned state, the first anchoring plate 18 is fixed to the upper end 11a of the PCa concrete body 11, thereby maintaining the tensioned state of the first unbonded PC tendon 17. Here, the first unbonded PC tendon 17 is tensioned in two stages during the construction stage: pre-tensioning and full tensioning, as will be described in detail below.

[0028] The first sheath pipe 16 is not filled with grout, and therefore the first unbonded PC steel member 17 is literally in an unbonded state inside the first sheath pipe 16.

[0029] 2, the PCa connection 20 has a rectangular parallelepiped PCa concrete body 21, and a plurality of second sheath pipes 26 (four in the illustrated example) are buried inside the PCa concrete body 21 at positions corresponding to the first sheath pipes 16, and second unbonded PC steel members 27 are inserted into each second sheath pipe 26. Here, the second unbonded PC steel members 27 are PC steel rods.

[0030] The upper end of the first unbonded PC tendon 17 and the lower end of the second unbonded PC tendon 27 are connected to each other via a mechanical joint 35 such as a coupler.

[0031] The second unbonded PC tendon 27 protrudes upward from the upper end 21a of the PCa concrete body 21, and by tightening the nuts 29 in the fully tensioned state, the second anchoring plate 28 is fixed to the upper end 21a of the PCa concrete body 21, and the fully tensioned state of the second unbonded PC tendon 27 is maintained. More specifically, the full tensioning causes both the first unbonded PC tendon 17 and the second unbonded PC tendon 27 to be fully tensioned simultaneously.

[0032] The second sheath pipe 26 is not filled with grout either, and therefore the second unbonded PC steel member 27 is literally in an unbonded state inside the second sheath pipe 26.

[0033] 1 and 2, in the PCa joint 20, steel beams 22A, 22B formed of mutually intersecting H-shaped steel beams are embedded inside a rectangular parallelepiped PCa concrete body 21, and each steel beam 22A, 22B protrudes laterally from four side surfaces of the PCa concrete body 21 to form four brackets. In the illustrated example, two steel beams 22B are welded to one continuous steel beam 22A, and the intersection of the cross-shaped steel beams 22 is disposed at the center of the PCa concrete body 21 in a plan view, but the intersection of the cross-shaped steel beams 22 may be offset from the center of the PCa concrete body 21. Furthermore, the steel beams 22 may protrude from one to three of the four side surfaces.

[0034] A steel surrounding plate 23 is disposed on the side of the PCa concrete body 21 in an area that does not interfere with the bracket 22 that protrudes laterally, and the boundary between the surrounding plate 23 and the bracket 22 is welded together. This surrounding plate 23 functions as a vertical stiffener.

[0035] With this configuration, all sides of the PCa concrete body 21 of the PCa connection 20 are completely surrounded by the brackets 22 that protrude laterally and the surrounding plates 23. These surrounding plates 23 can increase the shear strength of the PCa connection 20. Furthermore, at the manufacturing factory, the PCa concrete body 21 is manufactured by filling concrete into the surrounding plates 23 from the state shown in Figure 1, so the surrounding plates 23 also serve as formwork when manufacturing the PCa concrete body 21.

[0036] Above and below the surrounding plates 23 that surround the four sides of the PCa joint 20, endless (in the illustrated example, rectangular frame-shaped) steel band plates 24 are arranged, extending circumferentially around the PCa joint 20, and are welded or bolted to the upper and lower flanges of each bracket 22.

[0037] In addition, a rib plate 25 is welded to the inside of the band plate 24, and the rib plate 25 is embedded inside the PCa concrete body 21, thereby ensuring a strong connection of the band plate 24 to the PCa concrete body 21.

[0038] By wrapping the surrounding plate 23 around the PCa concrete body 21 from the outside with upper and lower band plates 24, the stress transmission performance from the steel beam 60 to the PCa joint 20 and the PCa column 10 can be improved.

[0039] A first joint 41 is formed between the PCa column 10 and the PCa joint 20, and the first fixing plate 18 is embedded in the first joint 41.

[0040] Here, the PCa joint 20 shown in Figures 1 and 2 can be called a surrounding plate type PCa joint.

[0041] The PCa connection 20A shown in Figure 3 differs from the PCa connection 20 in that it does not have the surrounding plate 23 and instead has multiple ties 32 surrounding multiple joint assembly bars 31 extending vertically. Each tie bar 32 extends circumferentially around the PCa connection 20A.

[0042] In addition, a vertical stiffener 33 is welded to the end of the bracket 22, and similarly to the surrounding plate 23, the shear strength of the PCa joint 20A is increased.

[0043] The PCa joint 20A shown in FIG. 3 can be called a horizontal reinforcement type PCa joint.

[0044] Although not shown, instead of the hoops 32 extending circumferentially around the PCa joint 20A as shown in Figure 3, a configuration may be applied in which multiple U-shaped reinforcement bars are used to restrain the multiple joint assembly bars at each corner of the PCa joint from the outside. Because the U-shaped reinforcement bars are inserted from the outside of the multiple joint assembly bars, this type of PCa joint can be called an insert-reinforcement type.

[0045] According to the PCa joint 50, the first unbonded PC steel 17 and the second unbonded PC steel 27, which are inserted into the first sheath pipe 16 of the PCa column 10 and the second sheath pipe 26 of the PCa joint 20, respectively, are connected via a mechanical joint 35, and both unbonded PC steels 17, 27 are fully tensioned, thereby eliminating the need for a longer construction period due to filling the sheath pipes 16, 26 with grout.

[0046] As will be described in detail below, after the PCa column 10 is erected, the first unbonded prestressing tendon 17 is provisionally tensioned, and this provisional tensioning of the first unbonded prestressing tendon 17 allows the PCa column 10 to stand on its own without any bracing members. Then, a PCa connection 20 is installed in the free-standing PCa column 10, and the first unbonded prestressing tendon 17 and the second unbonded prestressing tendon 27 are connected via a mechanical joint 35, after which the first unbonded prestressing tendon 17 and the second unbonded prestressing tendon 27 are fully tensioned.

[0047] This construction eliminates the need for damage treatment that occurs when conventional measures are taken to maintain the upright position of the PCa column 10, namely, by attaching a support member to the side of the PCa column and fixing one end of the support member to a jig installed on the slab.

[0048] As shown in Figure 4, a plurality of PCa joint bodies 50 are installed side by side on each floor, and the brackets 22 of each PCa joint body 50 are connected to steel beams 60 via splice plates 65 and high-tension bolts (not shown), thereby forming the frame for each floor. The frames for each floor are then stacked one above the other to form a hybrid frame 100 for a given floor. Here, Figure 4 shows a portion of the hybrid frame 100 that constitutes, for example, the first and second floors, but by stacking these frames over several tens of floors, a hybrid frame will be formed that constitutes a high-rise building or a super-high-rise building.

[0049] The hybrid frame 100 makes it possible to realize large-span buildings and high-rise buildings that take advantage of the advantages of both reinforced concrete and steel construction. In addition, by arranging band plates 24 around the PCa joints 20, high seismic performance can be achieved with as simple a reinforcement structure as possible.

[0050] [Construction method of PCa joint body according to the embodiment] Next, an example of a construction method for a PCa joint body according to an embodiment will be described with reference to Figures 5 to 9. Here, Figures 5 to 9 are, in this order, process diagrams of an example of a construction method for a PCa joint body according to an embodiment. Note that in the following explanation, a construction method for a PCa joint body 50 spanning two stories in a lower and upper floor relationship will be described, but the lower and upper floors can be applied to any two stories in a hierarchical relationship on all levels from the first floor to the nth floor in an n-story building, for example.

[0051] In the method of constructing a PCa joint, first, as shown in FIG. 5, a PCa column 10 of the lower floor is erected on a slab (not shown).

[0052] The PCa column 10 has a plurality of assembly reinforcements 11b extending vertically inside the PCa concrete body 11 and a plurality of rectangular frame-shaped tie bars 11c surrounding the outer periphery of each assembly reinforcement 11b, and further has a plurality of first sheath pipes 16 as described above, with a first unbonded PC steel material inserted inside each first sheath pipe 16.

[0053] If the PCa column 10 in the illustrated example is a PCa column 10 for the first floor, PC steel rods are embedded in a foundation slab (not shown), with a portion of the rod protruding above the foundation slab. When erecting the PCa column 10, the upper end of the PC steel rod protruding above the foundation slab is connected to the lower end of the first unbonded PC steel member 17 via a mechanical joint, and then the PCa column 10 is erected. On the other hand, if the PCa column 10 is a PCa column for the second or higher floor, the upper end of the second unbonded PC steel member protruding above the PCa joint of the lower floor (not shown) is connected to the lower end of the first unbonded PC steel member 17 via a mechanical joint, and then the PCa column 10 is erected.

[0054] After erecting the PCa column 10, each first unbonded PC steel member 17 is temporarily tensioned, and the first unbonded PC steel member 17 is fixed to the first fixing plate 18 arranged in the first joint space 42 above the PCa column 10, thereby making the PCa column 10 self-supporting (this is process A).

[0055] Next, as shown in Figure 6, the PCa joint 20 is lifted by a crane (not shown) and moved above the free-standing PCa column 10, and the second unbonded PC steel 27 in the second sheath pipe 26 of the PCa joint 20 is dropped downward, and the upper end of the corresponding first unbonded PC steel 17 and the lower end of the second unbonded PC steel 27 are connected via a mechanical joint 35.

[0056] Here, the lower part of the second sheath tube 26 is an expanded sheath tube 26A whose tube diameter is expanded, and the mechanical joint 35 is accommodated inside this expanded sheath tube 26A.

[0057] Furthermore, a curing member 37 is installed on the upper surface of the first anchoring plate 18 to surround the first unbonded prestressing steel member 17 protruding upward, and is used to prevent the upper and lower second sheath pipes 26 and first sheath pipes 16 from being filled with joint material to be placed in the first joint space 42 in a later process from entering the second sheath pipe 26 and first sheath pipe 16. Here, a bellows joint, for example, is used as the curing member 37.

[0058] Next, as shown in Fig. 7, the PCa connection 20 is erected above the PCa column 10 with the first joint space 42 secured, and a joint material is poured into the first joint space 42 to construct the first joint 41. Here, grout such as mortar is used as the joint material.

[0059] After the first joint 41 is constructed, the second unbonded PC steel 27 is tensioned, whereby the first unbonded PC steel 17 and the second unbonded PC steel 27, which are continuous with each other, are fully tensioned.

[0060] This full tension joins the PCa column 10 and the PCa joint 20, and the PCa joint 50 is constructed (this is process B).

[0061] In the method for constructing a PCa joint, the above-mentioned steps A and B are repeated to construct PCa joints 50 corresponding to two or more floors. Specifically, the PCa column 10 of the upper floor is lifted by a crane (not shown) and moved above the constructed PCa joint 50, the first unbonded PC steel member 17 in the first sheath pipe 16 of the PCa column 10 is dropped downward, and the upper end of the corresponding second unbonded PC steel member 27 is connected to the lower end of the first unbonded PC steel member 17 via a mechanical joint 35.

[0062] Here, the lower part of the first sheath tube 16 is an expanded sheath tube 16A whose tube diameter is expanded, and a mechanical joint 35 is accommodated inside this expanded sheath tube 16A.

[0063] In addition, a protective member 37 is installed on the upper surface of the second fixing plate 28 to surround the second unbonded PC steel 27 protruding upward, and protective material is provided to prevent the upper and lower first sheath pipe 16 and second sheath pipe 26 from being filled with joint material to be poured into the second joint space 44 in a subsequent process.

[0064] Next, as shown in Figure 9, the PCa column 10 is erected with the second joint space 44 secured above the PCa connection 20, and a joint material is poured into the second joint space 44 to construct the second joint 43. Thereafter, the PCa joint body 50 for the upper floor is constructed by carrying out construction similar to that shown in Figures 6 and 7.

[0065] According to the construction method of the PCa joint shown in the figure, in process B, the first unbonded PC steel 17 and the second unbonded PC steel 27, which are respectively inserted into the first sheath pipe 16 of the PCa column 10 and the second sheath pipe 26 of the PCa joint 20, are connected via a mechanical joint 35, and both unbonded PC steels 17, 27 are tensioned, thereby eliminating the need for a longer construction period due to filling the sheath pipes 16, 26 with grout.

[0066] In addition, in process A, by temporarily tensioning the first unbonded PC steel 17 provided on the PCa column 10 to make it self-standing, it is possible to eliminate the need for damage treatment that occurs when applying conventional measures to maintain the upright position of the PCa column 10.

[0067] The present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form. [Explanation of symbols]

[0068] 10: PCa pillar (PCaPC pillar) 11: PCa concrete body 11a:Top edge 11b: Assembly bar 11c: Stirrup 16: First sheath tube 16A: Widened sheath tube 17: First unbonded prestressing steel (unbonded prestressing steel) 18: First fixing plate 19: Nut 20, 20A: PCa joint (PCaPC joint) 21: PCa concrete body 21a: Upper end 22, 22A, 22B: Steel beam (bracket) 23: Enclosure 24: Band plate 25: Rib plate 26: Second sheath tube 26A: Widened sheath tube 27: Second unbonded prestressing steel (unbonded prestressing steel) 28: Second fixing plate 29: Nut 31: Joint assembly bar 32: Stirrup 33: Vertical stiffener 35: Mechanical coupling 37: Curing material (accordion joint) 41: First joint 42: First joint space 43: Second joint 44: Second joint space 50: PCa zygote (PCaPC zygote) 60: Steel beam 65: Splice plate 100: Hybrid frame structure

Claims

1. A PCa joint in which a PCa column made of precast concrete and having a first sheath pipe is joined to a PCa joint made of precast concrete and having a second sheath pipe and a steel beam, The PCa joint is disposed above the PCa column, and the first unbonded PC steel and the second unbonded PC steel, which are respectively inserted into the first sheath pipe and the second sheath pipe that are interconnected, are connected via a mechanical joint, and the first unbonded PC steel and the second unbonded PC steel are fully tensioned, A first fixing plate to which the first unbonded PC steel member is fixed is disposed in a first joint between the PCa column and the PCa connection, A second fixing plate to which the second unbonded PC steel member is fixed is disposed above the PCa joint, Above and below the PCa joint, endless steel band plates extending in the circumferential direction of the PCa joint are provided, and the steel beam extends laterally from between the upper and lower band plates, A PCa joint structure, characterized in that the first unbonded PC steel member is provisionally tensioned and then fully tensioned together with the second unbonded PC steel member.

2. A method for constructing a PCa joint by joining a PCa column made of precast concrete and having a first sheath pipe to a PCa joint made of precast concrete and having a second sheath pipe and a steel beam, Step A includes temporarily tensioning a first unbonded PC steel member that is inserted into the first sheath tube of the PCa column and protruding upward, and fixing the first unbonded PC steel member with a first fixing plate disposed in a first joint space above the PCa column, thereby making the PCa column self-supporting; a step B of connecting a second unbonded PC steel member that is inserted into the second sheath pipe of the PCa joint and protruding downward to the first unbonded PC steel member that protrudes upward via a mechanical joint, tensioning the second unbonded PC steel member and the first unbonded PC steel member, and fixing the second unbonded PC steel member with a second fixing plate arranged in a second joint space above the PCa joint.

3. 3. The method for constructing a PCa joint body according to claim 2, characterized in that in step B, curing is performed in the first joint space to prevent the joint material from entering the first sheath pipe and the second sheath pipe that communicate with the first joint space, the joint material is cast into the first joint space, and the main tensioning is performed after the joint material has hardened.

4. 4. The method for constructing a PCa joint body according to claim 2 or 3, characterized in that the process A and the process B are repeated to construct the PCa joint body corresponding to two or more stories.

5. An endless steel band plate extending in the circumferential direction of the PCa joint is provided above and below the PCa joint, The method for constructing a PCa joint body according to any one of claims 2 to 4, characterized in that the steel beam extends laterally from between the upper and lower band plates.

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