JP6590571B2 - Precast concrete beam end joint structure and precast concrete beam column frame - Google Patents

Description

  The present invention relates to a joint structure of precast concrete beam ends and a precast concrete beam column frame.

As is well known, a reinforced concrete structure is particularly excellent in strength as a structure of a building structure, and is used in medium- and high-rise buildings. In the above building structure, for the purpose of shortening the construction period, reducing costs, ensuring the construction quality, etc., for example, the beam is prefabricated concrete (hereinafter referred to as PC) as a beam in advance in a factory and assembled on site, Widely done.
In assembly on site, the PC beam members may be joined with their end faces facing each other.
For example, in Patent Document 1, as a joint structure between PC beams, beam principal bars protruding from the respective PC beam end portions are added to the reinforcing bars to form a lap joint, and the joint portion between the PC beam end portions is concrete. A bonding method for filling is disclosed.
Patent Document 2 discloses a method of disposing a steel frame at a joint portion as a joint structure between PC beams.
FIG. 5 shows a method disclosed in Patent Document 2, in which two PC beams 100 and 101 are formed by joining two PC columns erected on a foundation so that their end faces are opposed to each other at the center of the column interval. Shows the joint structure between the PC beams 100 and 101 in the column beam structure to be joined.
The PC beams 100 and 101 are provided with grooves 100d and 101d which are recessed from the upper surfaces 100b and 101b toward the lower surfaces 100c and 101c on the side of the joining end surfaces 100a and 101a and extend in the length direction and open to the joining end surfaces 100a and 101a. Yes. The PC beams 100 and 101 are installed such that their joint end faces 100a and 101a face each other, and a steel frame 102 is inserted into both the groove portions 100d and 101d. Further, the concrete 103 is filled in the grooves 100d and 101d so as to embed the steel frame 102.
In the joint structure of PC beams disclosed in Patent Document 1, a cast-in-place concrete formwork to be placed in the central joint is required. Since this formwork work is a dangerous work at a high place, it has been a hindrance to shortening the construction period and rationalizing the construction.
In the joint structure of the PC beam of Patent Document 2, a groove portion that opens at the joint end surface is formed, and the formwork on site of Patent Document 1 is unnecessary, but because the steel frame 102 is used for joining, A crane is required for the installation work of the steel frame 102, and it takes a lot of time for construction, and the construction cost increases. Moreover, since the steel frame 102 itself is expensive, material costs also increase.

Japanese Patent No. 4298678 JP 2011-122325 A

  In addition, the following problems occur due to the concave portions of the grooves 100d and 101d. That is, when the steel frame 102 is installed in the grooves 100d and 101d, the direction in which the steel frame 102 is inserted is limited to the upper side of the PC beams 100 and 101. Since it must be inserted so as to avoid the reinforcing bars, workability is poor. Furthermore, since the installation status of the steel frame 102 is limited to the confirmation from above the PC beams 100 and 101, it is difficult to confirm the status during and after the installation of the steel frame 102, and it is not easy to ensure the construction quality. . In particular, it was difficult to measure the clearance between the lower surface of the steel frame and the upper surface of the groove.

  The problem to be solved by the present invention is to provide a precast concrete beam end joint structure and a precast concrete beam column structure that are easy to construct and can reduce costs.

The present invention employs the following means in order to solve the above problems. That is, the present invention is a joint structure of a pair of PC beam ends that are butted together, and each of the pair of PC beams includes a thin-walled concrete portion in which the lower side of the end portion projects in the butting direction, and the thin-walled concrete portion. A bottom main bar extending in the length direction, and arranged such that end faces of the thin concrete portion face each other, and above the thin concrete portion, the lower main bars of each of the pair of PC beams A joint structure of the end of the PC beam, comprising: a reinforcing bar disposed across the bottom main bar, and a concrete part in which the reinforcing bar is embedded between the pair of PC beams. provide. As one aspect of the present invention, the reinforcing bar is disposed at a position substantially directly above the lower principal bar embedded in the thin-walled concrete portion.
According to the configuration as described above, since the member disposed across the pair of PC beams is a splicing member having a light weight, a crane is not necessary for the installation work. Therefore, the construction period can be shortened and the construction cost can be reduced.
Moreover, the member arrange | positioned ranging over a pair of PC beam is a reinforcing bar with a cross-sectional area smaller than a steel frame material. Thus, even when the reinforcing bar is installed inside the upper main bar and the shear reinforcing bar of the PC beam, the reinforcing bar can be easily installed, and therefore workability is good. In addition, material costs can be reduced.

Each of the pair of PC beams includes a shear reinforcement bar having a bottom portion embedded in the thin-walled concrete portion, and the reinforcing bar is disposed above the bottom main bar and away from the upper surface of the thin-walled concrete portion. .
According to the above configuration, the reinforcing bars are arranged away from the top surface of the thin-walled concrete portion so as not to contact with each other. Therefore, the concrete is uniformly filled around the reinforcing bars to increase the adhesion strength of the concrete. Enough can be secured. Further, the reinforcing bar is arranged so as to be a lap joint with respect to the lower end main reinforcing bar, so that a strong joint structure can be realized. For this reason, it is not necessary to connect between lower end main reinforcements with an expensive mechanical joint or a lap joint with a complicated reinforcing bar. Therefore, it is possible to reduce the number of joint parts and further reduce material costs and construction costs. Furthermore, since the PC beam is manufactured in the state where the bottom portion of the shear reinforcing bar of the thin-walled concrete portion is embedded in the thin-walled concrete portion, it is possible to reduce the amount of bar arrangement work on site.
In addition, the pair of PC beams are arranged so that the thin-walled concrete portion is in contact with each other, so that the thin-walled concrete portion can also serve as the lower end formwork of the joint structure of the PC beams, and the lower end formwork is unnecessary. .

Each of the pair of PC beams is open at least one side of the upper region of the thin concrete portion. As one aspect of the present invention, the end portion of the PC beam has an L shape in a longitudinal sectional view.
According to the configuration as described above, the installation work of the reinforcing bar is possible not only from above but also from the opened one side, so that workability is good. It is easy to visually check the reinforcing bar during the bar arrangement work or after the bar arrangement is completed, and it is easy to secure the construction quality.
In addition, especially when such a joint structure is used as the outer perimeter beam of a super high-rise building, the building plan is often made in a reverse beam type in which a floor slab is connected to the side of the girder. In particular, since it is possible to pass the reinforcement of the floor slab from the open side to the upper area of the thin-walled concrete part, construction of the building is easy. Moreover, it is possible to simultaneously place the joint portion between the PC beams and the slab main body portion, thereby reducing the number of concrete joints and improving the work efficiency.

  The PC beam column frame may include the above-described joint structure of the PC beam ends.

According to the present invention, it is possible to provide a precast concrete beam end joint structure and a precast concrete beam column structure that are easy to construct.
In a preferred embodiment, cost can be reduced.

It is the front view which carried out the partial cross section view of the beam column frame using the junction structure of the precast concrete beam end part shown as an embodiment of the present invention. The precast concrete beam end joined structure shown as the first embodiment of the present invention shows the installation status before placing concrete, (a) is a partially sectional front view, (b), (c) Is a cross-sectional view. It is the side view which carried out the partial cross section which shows the joining condition with the floor slab of the precast concrete beam edge part shown as the 1st Embodiment of this invention. The precast concrete beam end joined structure shown as the second embodiment of the present invention shows the installation situation before concrete placement, (a) is a partial cross-sectional front view, (b), (c) Is a cross-sectional view. It is sectional drawing which shows the joining structure of the conventional precast concrete beam edge part.

The present inventors do not connect the main bars of each PC beam by expensive mechanical joints as the joint structure of the PC beams, but rather the lower end concrete part of each PC beam in which the lower beam main bars are embedded. Joint structure of PC beam ends that can be connected with a small number of joint parts by placing the reinforcing bars above each other and placing the reinforcement bars above each other and connecting the bottom beam main bars with a lap joint. It led to invention of this. In addition, one of the features of the present invention is that the concrete parts at the lower ends of the PC beams facing each other are arranged to face each other, so that the concrete is placed at the joined parts without providing the lower end formwork at the joined parts of the PC beams. In this way, a joint structure of PC beams is formed.
Specifically, the joint structure between the PC beams facing each other is such that the longitudinal cross-sections of the PC beam end portions are L-shaped (first embodiment) and thin-walled portions that do not have a rising portion (second embodiment). Yes, the PC beam ends are arranged to face each other.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a partial cross-sectional front view of a beam column frame 1 including a PC beam end joint structure 2 shown as an embodiment of the present invention.

In the beam column frame 1, PC columns 3 and 4 are erected on the foundation or the like. The PC pillars 3 and 4 include main bars 3a and 4a and concrete parts 3c and 4c, respectively, and the main bars 3a and 4a are embedded in the concrete parts 3c and 4c. The ends of the main bars 3a and 4a protrude from the end surfaces 3d and 4d of the concrete portions 3c and 4c. The PC pillars 3 and 4 are manufactured in advance at a factory or the like, transported to an installation location, and installed.
On the sides of the PC pillars 3 and 4, PC beams 5 and 6 are installed so as to be placed on the end sides of the upper end faces 3d and 4d. The PC beams 5 and 6 are provided with upper main bars 5a and 6a, lower main bars 5b and 6b, and concrete parts 5c and 6c, respectively. The main bars 5a, 5b, 6a and 6b are provided on the concrete parts 5c and 6c, respectively. Buried. Similarly to the PC pillars 3 and 4, the PC beams 5 and 6 are also manufactured in advance in a factory, and are transported to the installation location and installed.
In the column-side end surfaces 5d and 6d, which are the end surfaces of the PC beams 5 and 6 on the side of the PC columns 3 and 4, the end portions of the upper main bars 5a and 6a and the lower main bars 5b and 6b are column-side end surfaces 5d and 6d. And extends above the end faces 3d and 4d of the PC pillars 3 and 4, respectively.
The PC beams 5 and 6 are joined by the joining structure 2 at the ends of the PC beams 5 and 6 on the side where they face each other. The joint structure 2 may be one of the joint structures 20 and 40 at the end of the PC beam shown as the first and second embodiments described later.
As shown in FIG. 1, the joint structure of the PC beam end portion of the present invention is the optimum position near the center of the span between adjacent columns. The PC beams are manufactured including the column beam joints, and the PC beams are connected near the center of the span, so that the number of joints can be reduced, and the construction period and cost can be reduced.

  In such a beam column structure 1, PC columns 3 and 4 are erected, PC beams 5 and 6 are installed on the sides of the columns, and the PC beams 5 and 6 are joined to each other to be described later. The PC beam end joint structures 20 and 40 shown as the embodiment of the present invention are formed, and the end surfaces 3d and 4d of the PC columns 3 and 4, the column side end surfaces 5d and 6d of the PC beams 5 and 6, and a mold (not shown) It is constructed by placing concrete in a space composed of frames.

[First Embodiment]
Next, the PC beam end joint structure 20 shown as the first embodiment will be described with reference to FIG. The joint structure 20 at the end of the PC beam can be applied as the joint structure 2 in the beam column frame 1 described with reference to FIG. FIG. 2 shows an installation state of the PC beam end joint structure 20 shown as the first embodiment before placing concrete between the beam ends. The longitudinal cross section of the end portion of the PC beam is L-shaped, (a) is a front view partially in cross section, (b) is an AA ′ sectional view, and (c) is a BB ′ sectional view.

The joint structure 20 is a structure in which the PC beams 21 and 22 are joined by a concrete that is placed so as to embed the reinforcing bars 31 between the reinforcing bars 31 described later and the ends of the PC beams 21 and 22.
Each of the PC beams 21 and 22 includes concrete parts 23 and 24, upper main bars 25 and 26, and lower main bars 27 and 28. The main bars 25, 26, 27, and 28 are respectively connected to the concrete part 23, 24 is embedded. The PC beams 21 and 22 have the same beam formation and width. Each column-side end of each of the PC beams 21 and 22 is configured as shown in FIG. 1 and joined to the PC columns 3 and 4. The PC beams 21 and 22 are manufactured in advance at a factory or the like, transported to an installation location, and installed.
The end portions of the PC beams 21 and 22 opposite to the column-side end portions are arranged so as to face each other. The opposite end portions that are abutted, that is, the joining end portions are joined together to form the joining structure 20. The concrete portions 23 and 24 include main bodies 23a and 24a, thin-walled concrete portions 23b and 24b, and rising portions 23c and 24c, respectively. At the joint ends of the PC beams 21 and 22, the thin concrete portions 23b and 24b and the rising portions 23c and 24c are connected to the main bodies 23a and 24a, respectively.
The thin concrete portions 23b and 24b are formed such that the lower sides of the joint ends of the PC beams 21 and 22 protrude from the main bodies 23a and 24a of the concrete portions 23 and 24 in the abutting direction of the PC beams 21 and 22, respectively. Yes. That is, in the thin concrete portions 23b and 24b, the upper surfaces 23d and 24d are formed at a position substantially parallel to the upper surfaces 23f and 24f of the PC beams 21 and 22 and lower than the upper surfaces 23f and 24f. The lower surfaces 23e, 24e and the side surfaces of the thin concrete portions 23b, 24b form the same plane as the lower surfaces and the side surfaces of the PC beams 21, 22, respectively.
The thin concrete portions 23b and 24b have substantially the same height, and form a plane in which the upper surfaces 23d and 24d of the thin concrete portions 23b and 24b are substantially continuous when the PC beams 21 and 22 are brought into contact with each other. To be formed.

The rising portion 23c of the PC beam 21 on the left is such that one side portion of the joint end portion of the PC beam 21 is as long as the thin concrete portion 23b from the main body 23a of the concrete portion 23 in the butting direction of the PC beam 21. It is formed so as to protrude. That is, in the rising portion 23 c, the inner side surface 23 g which is one side surface thereof is located on the inner side in the width direction of the PC beam 23 from the side surface of the PC beam 21. The lower end of the rising part 23c is joined to the side of the thin concrete part 23b. The upper surface, the lower surface, and the outer side surface 23h, which is the side surface opposite to the inner side surface 23g, are on the same plane as the upper surface, the lower surface, and the outer side surface of the PC beam 21, respectively.
The rising portion 24c of the right PC beam 22 is formed to have the same width as the rising portion 23c of the left PC beam 21 and the same width as the rising portion 23c. As can be seen from FIGS. 2B and 2C, the rising portion 24c is located on the same side as the rising portion 23c when the PC beams 21 and 22 are abutted with each other, and the rising portions 23c and 24c Both inner side surfaces 23g and 24g are formed at positions that constitute a substantially continuous plane.

By having the above configuration, in each of the PC beams 21 and 22, at least one side of the upper regions 23j and 24j of the thin concrete portions 23b and 24b is opened. That is, the region 23j defined by the upper surfaces 23d and 24d of the thin concrete portions 23b and 24b, the inner side surfaces 23g and 24g of the rising portions 23c and 24c, and the end surfaces 23i and 24i of the main bodies 23a and 24a of the PC beams 21 and 22. , 24j communicate with the outside on the side opposite to the rising portions 23c, 24c.
The upper main bars 25 and 26 are embedded in the vicinity of the upper ends of the main bodies 23a and 24a of the concrete portions 23 and 24, respectively. The upper main bars 25 and 26 are arranged at positions higher than the upper surfaces 23d and 24d of the thin concrete portions 23b and 24b, and extend in the length direction of the PC beams 21 and 22. The ends of the upper main bars 25 and 26 protrude from the end surfaces 23i and 24i of the main bodies 23a and 24a of the concrete portions 23 and 24 with the same length as the thin concrete portions 23b and 24b. The upper main bars 25 and 26 are arranged in a symmetrical positional relationship on the cross section of the concrete parts 23 and 24 so that the ends of the PC beams 21 and 22 can be connected when the PC beams 21 and 22 are brought into contact with each other. Yes.
The bottom main bars 27 and 28 extend in the length direction of the PC beams 21 and 22 at positions lower than the upper surfaces 23d and 24d of the thin-walled concrete portions 23b and 24b inside the main bodies 23a and 24a of the concrete portions 23 and 24, respectively. To be buried. The bottom main bars 27 and 28 extend from the main bodies 23a and 24a to the thin concrete portions 23b and 24b, respectively, and terminate in the vicinity of the end surfaces of the thin concrete portions 23b and 24b.

The shear reinforcement bars 29 and 30 are disposed so as to surround the upper end main bars 25 and 26 and the lower end main bars 27 and 28 in the circumferential direction of the PC beams 21 and 22. The shear reinforcement bars 29 and 30 are disposed so that the main bodies 23a and 24a of the concrete portions 23 and 24 are entirely embedded in the concrete, and the bottom portions of the thin concrete portions 23b and 24b are thin concrete. It is embedded in the parts 23b and 24b, and is arranged so that the upper part is exposed to the regions 23j and 24j.
The shear reinforcement bars 29 and 30 are arranged at regular intervals in the length direction in the main bodies 23 a and 24 a of the PC beams 21 and 22. In the thin concrete parts 23b and 24b, they are arranged at a constant interval, for example, about half, which is narrower than the arrangement interval in the main bodies 23a and 24a.

  The end portions of the PC beams 21 and 22 as described above are abutted with each other to form a joint structure 20 of the PC beam end portions. The end surfaces of the thin-walled concrete portions 23b and 24b and the end surfaces of the rising portions 23c and 24c are arranged to face each other. Since the upper surfaces 23d and 24d of the thin concrete portions 23b and 24b and the inner side surfaces 23g and 24g of the rising portions 23c and 24c are substantially continuous planes, the regions 23j and 24j are integrated into four directions. Is formed by a substantially rectangular parallelepiped space defined by the wall surfaces of the PC beams 21 and 22.

The joining structure 20 has a reinforcing bar 31 and concrete (not shown) placed in the regions 23j and 24j so as to bury the reinforcing bar 31. The reinforcing bar 31 is disposed above the thin concrete portions 23 b and 24 b, straddling the lower main bars 27 and 28 of the PC beams 21 and 22, and along the lower main bars 27 and 28.
The reinforcing bar 31 is disposed above the lower main bars 27 and 28 as a pair of joint reinforcing bars so as to correspond to the lower main bars and away from the upper surfaces 23d and 24d of the thin concrete portions 23b and 24b.
The reinforcing bar corresponding to each lower main bar is a deformed reinforcing bar having the same size as the lower bar main bar if the reinforcing bar strength is the same as that of the lower main bar. In addition, when using a reinforcing bar with a diameter smaller than the reinforcing bar diameter of the pair of lower main bars, it is necessary to use a reinforcing bar with a strength higher than that of the lower main bars and to ensure that the stress bearing performance of the lower main bars and the reinforcing bars is equal. is there.
Further, the clearance between the upper surfaces 23d and 24d of the thin-walled concrete portions 23b and 24b and the reinforcing bar 31 is provided so that the concrete can be uniformly distributed around the reinforcing bar. Specifically, in the case of using general concrete, it is desirable that the thickness is 25 mm or more.
Further, the vertical or horizontal clearance between the lower main bars 27 and 28 and the reinforcing bars 31 is 0.2 times or less of the overlapping length of the additional bars 31 and the lower main bars 27 and 28 and 150 mm or less. (The Architectural Institute of Japan “All-joint joint design guideline (draft) / commentary explanation”, 1996 edition, page 25).

  The ends of the opposed upper main bars 25 and 26 of the PC beams 21 and 22 are joined. In the first embodiment, the upper main bars 25 and 26 are joined by the mechanical joint 32, but the joining may be performed by pressure welding or a lap joint.

A reinforcing bar 31 is embedded between the PC beams 21 and 22, and concrete is placed in a gap portion between the opposing PC beams to form the joint structure 20. That is, the upper main reinforcing bars 25 and 26, the thin concrete portions 23b and 24b, which protrude from the end faces 23i and 24i and are joined to each other, located in the space formed by the regions 23j and 24j of the PC beams 21 and 22 that are abutted. Concrete is placed so as to embed the shear reinforcement bars 29 and 30 and the reinforcing bar 31 protruding upward from the top. The reinforcing bar is arranged on the inner side of the plurality of shear reinforcing bars, and is provided at a position almost directly above the lower principal bar embedded in the thin-walled concrete portion.
By fixing the reinforcing bar to the inner side of the shear reinforcing bar along the beam axis direction so that it intersects with multiple shear reinforcing bars, the reinforcing bar is in the concrete in high stress state constrained by the shear reinforcing bar. Will be placed.
The burden stress of the lower main bar is once transmitted to the thin-walled concrete around the lower main bar, and then transmitted from the concrete portion restrained by the shear reinforcing bar to the reinforcing bar. As a result, although the lower main bars are not geometrically continuous, the stress borne by one lower main bar is transmitted to the other lower main bar via the perforated joint.
Further, the reinforcing bar is fixed to the shear reinforcing bar with a binding line, or a concrete block having a block height of about the cover thickness is arranged on the upper surface of the thin concrete part and installed on the concrete block.

  The strength of the concrete to be cast is set to the same level or high strength as the concrete constituting the PC beams 21 and 22. By placing high-strength concrete in the gaps between the PC beams, the shear resistance function of the concrete is increased, and a strong joint structure of the PC beam ends can be formed.

  Next, a method for constructing the joint structure 20 at the PC beam end will be described.

First, the PC beams 21 and 22 are arranged so that the end faces of the thin concrete portions 23b and 24b of the PC beams 21 and 22 face each other.
Next, the end portions of the opposing upper principal bars 25 and 26 of the PC beams 21 and 22 are joined. Further, the reinforcing bar 31 is disposed above the thin concrete parts 23b, 24b, more specifically, the upper surfaces 23d of the thin concrete parts 23b, 24b above the lower principal bars 27, 28 of the PC beams 21, 22, respectively. It is disposed at a position away from 24d, straddling the lower main bars 27, 28 and along the lower main bars 27, 28.
Thereafter, a formwork (not shown) is installed on the side surface of each of the PC beams 21 and 22 opposite to the rising portions 23c and 24c, and the open sides of the regions 23j and 24j are closed.
Finally, concrete is cast from above into the regions 23j and 24j whose sides are closed. After curing the concrete, demold.

  Next, the operation and effect of the joint structure 20 at the PC beam end will be described.

According to the above configuration, the reinforcing bar 31 is located at a position above the lower main bars 27 and 28 of the PC beams 21 and 22 and away from the upper surfaces 23d and 24d of the thin concrete portions 23b and 24b. 27 and 28, and is disposed along the bottom main bars 27 and 28. That is, the reinforcing bar 31 is disposed so as to be a lap joint with respect to the lower end main bars 27 and 28.
In addition, the space between the upper surfaces 23d and 24d of the thin-walled concrete portions 23b and 24b and the reinforcing bar 31 is filled with the cast concrete densely.

  A robust joint structure can be realized by the above-described joint strength by the lap joint and the adhesion strength of the concrete that is densely placed.

As described above, the use of the reinforcing bar 31 enables a strong joint between the PC beams 21 and 22, and therefore there is no need to connect the lower end main bars 27 and 28 with an expensive mechanical joint. Therefore, the number of joint parts is small, and material costs and construction costs can be reduced.
Moreover, since the member arrange | positioned straddling between the PC beams 21 and 22 is a light reinforcing bar, a crane is unnecessary for installation work. Therefore, the construction period can be shortened and the construction cost can be reduced.
The reinforcing bar 31 is a deformed reinforcing bar having a diameter equal to or smaller than the reinforcing bar diameter of the lower beam main bar, and is installed inside the upper main bars 25 and 26 and the shear reinforcing bars 29 and 30. Further, since the reinforcing bar is a short reinforcing bar, the installation work is easy even when it is fixed to the inside of the shear reinforcing bar with a binding wire. In addition, the material cost is low compared to the case where the beam main bars are connected by a mechanical joint or the like.
In the first embodiment, each of the PC beams 21 and 22 is open on at least one side of the upper regions 23j and 24j of the thin concrete portions 23b and 24b. Therefore, the installation work of the reinforcing bar 31 is possible not only from the upper side of the PC beams 21 and 22, but also from the opened one side, so that the workability is good. Visual confirmation is possible even during the reinforcement work of the reinforcing bar 31 or after the completion of the reinforcement work, and it is easy to ensure construction quality.
When such a joint structure 20 is used as the outer peripheral girder of a super high-rise building, the building plan is often made in a reverse beam type in which a floor slab is connected to the side surface of the girder. Especially in such a case, as shown in FIG. 3, it is possible to pass the bar slab reinforcement 33 from the open side of the upper regions 23j, 24j into the upper regions 23j, 24j. The construction of the building is easy.

  Since one side of the upper region 23j, 24j of each of the PC beams 21, 22 is a rising portion 23c, 24c, the side is necessary when placing concrete in the region 23j, 24j. It is not necessary to install a side mold. Therefore, the man-hour required for installation can be reduced.

  In addition, the shear reinforcement bars 29 and 30 located in the thin-walled concrete parts 23b and 24b are manufactured in such a manner that the PC beams 21 and 22 are manufactured with the bottoms embedded in the thin-walled concrete parts 23b and 24b. The amount of work can be reduced.

  In the thin concrete portions 23b and 24b, the shear reinforcement bars 29 and 30 are arranged at a constant interval that is narrower than, for example, about half of the arrangement interval in the main bodies 23a and 24a. Therefore, the joining structure can be made more robust.

[Second Embodiment]
Next, the PC beam end joint structure 40 shown as the second embodiment will be described with reference to FIG. The joint structure 40 at the end of the PC beam can be applied as the joint structure 2 in the beam column frame 1 described with reference to FIG. FIG. 4 shows an installation state of the PC beam end joint structure 40 shown as the second embodiment before placing concrete between the beam ends. The longitudinal cross section of the PC beam end is only a thin wall having no rising part, (a) is a front view partially in cross section, (b) is an AA ′ cross section, and (c) is a BB ′ cross section. FIG.

  The difference between the joint structure 40 and the joint structure 20 shown as the first embodiment is that the concrete portions 43 and 44 of the PC beams 41 and 42 to be used are shown in FIGS. 2B and 2C. It does not have the leading parts 23c and 24c.

That is, each of the PC beams 41 and 42 is open on both sides of the upper regions 43j and 44j of the thin concrete portions 43b and 44b. The regions 43j and 44j defined by the upper surfaces 43d and 44d of the thin concrete portions 43b and 44b of the PC beams 41 and 42 and the end surfaces 43i and 44i of the main bodies 43a and 44a communicate with the outside on both sides.
The end portions of the PC beams 41 and 42 manufactured in this way are abutted with each other to form a joint structure 40 of the PC beam end portions. The end surfaces of the thin-walled concrete parts 43b and 44b are arranged to face each other. The upper surfaces 43d and 44d of the thin concrete portions 43b and 44b are substantially continuous planes.
The PC beams 41 and 42 have upper main bars 25 and 26, lower main bars 27 and 28, shear reinforcement bars 29 and 30, and the ends of the PC beams 41 and 42 are joined to each other. It is the same as in the first embodiment that 40 has the reinforcing bar 31 and the concrete placed in the regions 43j and 44j so as to bury the reinforcing bar 31.

Next, a method for constructing the joint structure 40 at the PC beam end will be described.
First, similarly to the first embodiment, the PC beams 41 and 42 are arranged so that the end surfaces of the thin concrete portions 43b and 44b of the PC beams 41 and 42 face each other, and the upper end principal bars 25 facing each other. , 26 are joined to each other, and a reinforcing bar 31 is provided.
Thereafter, molds (not shown) are installed on both side surfaces of the PC beams 41 and 42, and both sides of the regions 43j and 44j are closed.
Finally, concrete is placed from above into the regions 43j and 44j closed on both sides. After curing the concrete, demold.

Next, the operation and effect of the joint structure 40 at the end of the PC beam will be described.
In the configuration as described above, both sides of the upper regions 43j and 44j of the PC beams 41 and 42 are opened.

  Therefore, the installation work of the reinforcing bar 31 can be performed not only from above the PC beams 41 and 42 but also from both opened sides, so that the workability is further improved. Visual confirmation is possible even during the bar arrangement work of the reinforcing bar 31 or after the bar arrangement is completed, and it is easy to ensure construction quality.

  In addition, in the case where the floor slab is connected to the side surface of the large beam as shown in FIG. 3, it is possible to pass the bar slab bar arrangement from both sides of the upper regions 43j and 44j into the upper regions 43j and 44j. Therefore, construction of the building becomes easier.

  This second embodiment can realize a robust joint structure with an open lap joint, etc., and can reduce the number of joint parts and reduce material costs and construction costs. The first embodiment can reduce the amount of reinforcement work by installing shear reinforcement bars in the thin-walled concrete portion in advance, which can shorten the period and reduce the construction cost. Needless to say, the same effect can be achieved.

The present invention is not limited to the above-described embodiments, and various modifications and improvements of those skilled in the art using the basic concept of the present invention described in the claims are also included in the present invention. For example, in the above-described embodiment, the longitudinal sections of the PC beam end portions are L-shaped or thin-walled portions that do not have a rising portion. U shapes may be used. When the vertical cross section is U-shaped, it is possible to reduce the formwork on the beam side surface.
Moreover, in the said embodiment, although arrange | positioned so that a lower end main reinforcement and a reinforcing bar may make a pair, compared with a lower end main reinforcement, a lower end main reinforcement and a reinforcing bar use a deformed reinforcing bar with a large diameter and a lower end. If the stress bearing performance equivalent to that of the main bar can be ensured, the number of reinforcing bars can be less than the lower main bar. When the number of the reinforcing bars is reduced, the number of fixing points of the reinforcing bars is reduced, so that the work efficiency of the bar arrangement work can be increased.

DESCRIPTION OF SYMBOLS 1 Beam-column frame using joint structure of precast concrete beam end 2 Precast concrete beam end joint structure 3, 4 Precast concrete column 5, 6 Precast concrete beam 20 Precast concrete beam end joint structure 21, 22 Precast concrete Beams 23 and 24 Concrete sections 25 and 26 Upper main bars 27 and 28 Lower main bars 29 and 30 Shear reinforcing bars 31 Reinforcement 32 Mechanical joint 40 Precast concrete beam end joint structure 41 and 42 Precast concrete beams 43 and 44 Concrete section

Claims (4)

It is a joint structure of a pair of precast concrete beam ends faced together,
Each of the pair of precast concrete beams has an L-shaped longitudinal section at the end of the beam , a thin concrete portion projecting in a butting direction on the lower side of the end portion, a rising concrete portion rising from an upper surface of the thin concrete portion, A lower end main reinforcing bar extending in the length direction in the thin-walled concrete portion, and disposed so that the end surfaces of the thin-walled concrete portion face each other.
Above the thin-walled concrete part, straddling between the lower principal bars of each of the pair of precast concrete beams, and a reinforcing bar disposed along the lower principal bars,
Between the pair of precast concrete beams, a concrete portion placed so as to bury the reinforcing bar,
A precast concrete beam end joint structure. It is a joint structure of a pair of precast concrete beam ends faced together,
Each of the pair of precast concrete beams has only a rectangular thin wall with a vertical section not having a rising portion at the beam end, a thin concrete portion in which the lower side of the end protrudes in the abutting direction, and a long length in the thin concrete portion. A lower end main reinforcing bar extending in the vertical direction, the end surfaces of the thin concrete portion are arranged to face each other,
Above the thin-walled concrete part, straddling between the lower principal bars of each of the pair of precast concrete beams, and a reinforcing bar disposed along the lower principal bars,
Between the pair of precast concrete beams, a concrete portion placed so as to bury the reinforcing bar,
A precast concrete beam end joint structure. Each of the pair of precast concrete beams includes a shear reinforcing bar having a bottom portion embedded in the thin-walled concrete portion,
The joint structure of the end part of the precast concrete beam according to claim 1 or 2 , wherein the reinforcing bar is disposed above the lower main bar and away from the upper surface of the thin concrete part.   The precast concrete beam column structure provided with the junction structure of the precast concrete beam end part as described in any one of Claim 1 to 3.

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