JP7381307B2 - Column beam joint structure - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act ▲1▼ Publication date: July 20, 2020 Publication: 2019 Conference (Hokuriku) Academic Lecture Abstracts Architectural Design Presentation Abstracts, pp. 115-116, General Foundation Architectural Institute of Japan ▲2▼ Publication date: July 20, 2020 Publication: 2019 Annual Conference (Hokuriku) Academic Lecture Abstracts Architectural Design Presentation Abstracts, pp. 117-118, Architectural Institute of Japan ▲ 3▼Publication date: September 1, 2020 Publication: Okumura Gumi Technical Annual Report No. 45, pp. 77-84, Okumura Gumi Technical Research Institute Co., Ltd.

The present invention relates to a structure at a joint between a column and a flat beam.

A flat beam construction method using flat beams with a width wider than the column width has been proposed for buildings with reinforced concrete rigid-frame frames. This flat beam construction method can keep the beam height small and create an open space under the beam, making it possible to lower the overall height of the building while ensuring sufficient interior height. . However, in the flat beam construction method, since the beam height is small, the bending moment that can be supported at the joint between the column and the flat beam is small. Further, since the range of the flat beam located outside the column width (the protruding portion) is not fixed to the column, its rigidity is low and deformation is likely to occur.

Therefore, for example, in Patent Document 1, a protrusion part that is integral with the column and protrudes in the beam axis direction and in a direction orthogonal to the beam axis is provided at the joint between the column and the flat beam, and the protrusion part from the column to the protrusion part is provided. A technique has been disclosed to make the proof stress sufficiently larger than the proof stress of the beam end. Specifically, the pitch of the stirrups at the jump-out part was set to about half the pitch of the stirrups in the beam section, and in addition to the upper and lower main reinforcements that penetrated the column cross section, reinforcement bars were added to the jump-out part parallel to the main reinforcements. Adding. Additionally, if necessary, reinforcing reinforcements may be added to the main reinforcements of the columns. By densely arranging reinforcement at the protrusion in this way, the rigidity and strength of the protrusion are increased, and joining to the protrusion provides the same structural performance as joining to a column. .

In addition, in Patent Document 2, in a joint structure between a corner column and a flat beam that is shifted to one side, U-shaped reinforcement bars surrounding a plurality of beam main reinforcements are embedded in the protruding part (projecting part), and the flat beam is A technique is disclosed in which a U-shaped cap line is embedded in the end portion.

Patent No. 4105191 Patent No. 6243238

However, if the number of reinforcing bars at joints and projecting parts is significantly increased as in the technique disclosed in Patent Document 1, it becomes difficult to construct the reinforcing bars. In addition, since the beam width is wider than the column width, torsional deformation occurs in the joint due to bending applied to the outer part of the column width of the flat beam, but it is disclosed in Patent Document 1 mentioned above that this can be completely suppressed. However, the structural performance of the beam may be overestimated because it cannot be fully estimated using the technology that has been developed.

In addition, in a joint structure in which a column and a flat beam are joined in a T-shape, reinforcing bars are not placed near the outer end face of the protruding part, so cracks occur on the outer end face due to twisting due to shear force. There is a risk of

In view of the above points, the present invention provides a joint structure between a column and a flat beam that can simplify reinforcement construction, suppress torsional deformation, and suppress the occurrence of cracks on the outer end surface of the protruding part. The purpose is to provide.

The present invention provides a joint where a column and a flat beam having a beam width wider than the column width of the column are connected such that one outer surface of each of the column and the flat beam is flush with the other side. The structure includes a structure in which a plurality of beam main reinforcements arranged in the flat beam are surrounded inside the column wall of the column including a joint between the column and the flat beam, A plurality of first reinforcing bars divided into two and each having a U-shape are arranged on the inside of the column width of the column, with both ends of the U-shape overlapping in the column width direction. It is fixed to the main reinforcement, and extends from the outer surface side of the flat beam toward the inside of the flat beam from a straight base and both ends of the base on the outside of the width of the column among the flat beams. A U-shaped second reinforcing bar consisting of two legs is arranged, and the two legs are respectively connected to the first reinforcing bars at the portions where they intersect with the plurality of first reinforcing bars. It is characterized by being fixed.

According to the present invention, since the main beam reinforcement in the joint part and the protruding part which is the inside part of the column of the column of the flat beam is restrained by the first reinforcing reinforcement, deformation due to shear force and torsion in these parts is restrained. It becomes possible to suppress the This makes it possible to particularly suppress deformation due to torsion, compared to the case of reinforcing as disclosed in Patent Document 1 mentioned above. Moreover, compared to the reinforcement configuration in the technique disclosed in Patent Document 1, it is possible to suppress deformation due to shear force more effectively with the same amount of reinforcement.

Furthermore, the presence of the second reinforcing bars makes it possible to suppress cracks caused by twisting due to shear force on the outer surface flush with the outer surface of one of the columns, that is, on the back surface.

In the present invention, it is preferable that the U-shaped base of the second reinforcing bar is located closer to the outer surface than the first reinforcing bar closest to the flush outer surface.

In this case, it becomes possible to effectively suppress the occurrence of the above-mentioned cracks.

In the present invention, a plurality of third reinforcing bars are arranged in the flat beam only on the outside of the column, and the third reinforcing bars are arranged in the plurality of beams arranged in the flat beam. It is composed of a surrounding reinforcement that surrounds the outer periphery of the main reinforcement, and a plurality of connecting reinforcements that are connected in the direction in which the column extends in the middle of the surrounding reinforcement.

From this , since the third reinforcing bars are connected in the middle by the core reinforcing bars, it becomes possible to effectively suppress deformation due to shear force in the part of the flat beam where the second reinforcing bars are installed internally. . This makes it possible to suppress deformation due to shear force more effectively than in the case where no core reinforcement is provided as disclosed in Patent Document 1 mentioned above.

FIG. 1 is a schematic cross-sectional view in the XY plane of a beam-column joint structure according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. 1. FIG. 2 is a schematic cross-sectional view taken along line III-III in FIG. 1. A schematic cross-sectional view taken along the IV-IV line in FIG. 1. A schematic cross-sectional view taken along the V-V line in FIG. 1. A schematic cross-sectional view taken along the VI-VI line in FIG. 1.

A column-beam joint structure 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6.

The column-beam joint structure 100 includes a joint 30 formed by integrally constructed reinforced concrete (RC) pillars 10 and flat beams 20 joined in a T-shape. For example, the pillar 10 is a side pillar located on the side of a building. The column-beam connection structure 100 or the structure including the column-beam connection structure 100 may be made of cast-in-place concrete or half precast concrete.

The flat beam 20 is a flat beam whose beam width Bg is wider than the beam width Dg (not shown), and the beam width Bg is wider than the column width Bc. The ratio of the beam width Bg to the column width Bc (column/beam width ratio) is preferably 3 or less. A portion of the flat beam 20 that extends outward from the side surface of the column 10 in the beam width direction of the flat beam 20 from the joint portion 30 serves as a protruding portion 31 . The dimensions of the portion of the protruding portion 31 that protrudes from the side surface of the column 10 are preferably equal to or less than the column width Bc and column depth Dc, and twice as large as the beam depth Dg of the flat beam 20.

Here, we will explain the case where the axis Oc of the column 10 and the axis Og of the flat beam 20 intersect, that is, the case where the column 10 is joined to the flat beam 20 without eccentricity, but even if there is eccentricity, That is, the column 10 may be joined to the flat beam 20 in a manner that is offset to one side. In this case, the beam width Bg when calculating the above ratio (column/beam width ratio) is preferably calculated as the sum of twice the larger width of the protruding portion 31 and the width of the column 10. .

Hereinafter, the direction in which the axis Og of the flat beam 20 extends is referred to as the X-axis direction, the direction in which the axis Oc of the column 10 extends is referred to as the Z-axis direction, and the direction perpendicular to the X-axis and the Z-axis is referred to as the Y-axis direction. It will be explained as follows.

The column 10 is internally provided with a plurality of column main reinforcements 11 extending in the Z-axis direction and a plurality of hoop reinforcements 12 surrounding the outer periphery of these column main reinforcements 11 and arranged at intervals in the Z-axis direction. There is.

A plurality of beam main reinforcements 21 extending in the X-axis direction are arranged in the flat beam 20. Although the main beam reinforcements 21 may be arranged at equal intervals in the Y-axis direction, it is preferable that the intervals are narrower inside the column than outside the column. Furthermore, the beam main reinforcements 21 are not limited to being disposed over almost the entire length of the flat beam 20, but may be disposed only within a part of the column. The main beam reinforcement 21 includes a fixing portion 21 a at an end on the outer surface side of the flat beam 20 that is flush with the outer surface of the column 10 , that is, at an end on the back surface of the flat beam 20 .

Further, in a portion of the flat beam 20 inside the column, that is, a portion consisting of the joint 30 and the protruding portion 31 between the column 10 and the flat beam 20, a plurality of torsion reinforcements are provided so as to surround the plurality of beam main reinforcements 21. The stripes 22 are arranged at intervals in the X-axis direction. The torsion reinforcing bars 22 correspond to the first reinforcing bars of the present invention.

Each torsion reinforcing bar 22 is divided into two parts each having a U-shape, and specifically, each torsion reinforcing bar 22 is comprised of a base part 22a and two legs 22b extending from both ends of the base part 22a. The base 22a is located in contact with the outer side of the end surface of the beam main reinforcement 21 disposed within the end of the projecting portion 31, and each foot portion 22b is disposed at intervals in the Y-axis direction. It is located in contact with the upper side of the upper end reinforcement and the lower side of the lower end reinforcement of the main reinforcement 21. The end portion of each leg portion 22b on the side not connected to the base portion 22a is directly or indirectly fixed to the beam main reinforcement 21 so as to have an overlapping portion within the column width.

Each of the torsion reinforcing bars 22 configured in this manner restrains the beam main reinforcements 21 in the joint portion 30 and the projecting portion 31, thereby suppressing deformation due to shear force and torsion in the joint portion 30 and the projecting portion 31. becomes possible.

This makes it possible to particularly suppress deformation due to torsion, compared to the case of reinforcing as disclosed in Patent Document 1 mentioned above. Moreover, compared to the reinforcement configuration in the technique disclosed in Patent Document 1, it is possible to suppress deformation due to shear force more effectively with the same amount of reinforcement. Further, the bending moment generated in the protruding portion 31 is transmitted to the column 10 as a torsion resistance force by the torsion reinforcement 23.

Furthermore, since each torsion reinforcing bar 22 has a U-shape, it is possible to arrange the bar by inserting it from the end face side of the projecting part 31 to the joint part 30 side, so that the reinforcing bar arrangement is easy. It's simple.

In addition, the torsion reinforcing bars 22 are as follows. The reinforcement may be arranged in an amount that makes it possible to suppress deformation due to shear force and torsion at the joint 30 between the column 10 and the flat beam 20 to a desired amount or less. Furthermore, although not shown, it is not preferable to arrange a core reinforcement that connects the torsion reinforcing bars 22 in the Z-axis direction in the middle, since this deteriorates the workability of the reinforcement.

Furthermore, a plurality of shear reinforcing bars 23 are arranged at intervals in the X-axis direction in a range of the flat beam 20 that is outside the column, that is, a portion outside the front and rear surfaces of the column 10 in the X-axis direction. There is. The shear reinforcing bars 23 correspond to the third reinforcing bars of the present invention.

The shear reinforcing bars 23 are preferably placed over the entire outside of the column of the flat beam 20, but only within the area outside the column of the flat beam 20 that is necessary for cross-sectional calculation. may be placed.

The shear reinforcing bars 23 include stirrups 24 surrounding the outer periphery of the plurality of main beam reinforcements 21 and a plurality of core reinforcing bars connected in the direction in which the column 10 extends, that is, the Z-axis direction, in the middle of one stirrup 24. It consists of 25. The stirrup muscles 24 correspond to the surrounding muscles of the present invention, and the core muscles 25 correspond to the connecting muscles of the present invention.

There is at least one core reinforcement 25 for each stirrup 24, but a plurality of core reinforcements 25 may be arranged at intervals in the Y direction. In this case, although they may be arranged at equal intervals in the Y direction, it is preferable that the intervals are narrower within the column width than outside the column width. Furthermore, the core reinforcement 25 may be arranged only within the column width.

The shear reinforcing bars 23 configured in this manner restrain the portions of the plurality of beam main reinforcing bars 21 outside the column width.

Since the shear reinforcing bars 23 are connected in the middle by the core reinforcing bars 25 in this way, it is possible to effectively suppress deformation due to shear force in the portion of the flat beam 20 in which the shear reinforcing bars 23 are installed. . This makes it possible to suppress deformation due to shear force more effectively than in the case where no core reinforcement is provided as disclosed in Patent Document 1 mentioned above.

The amount of shear reinforcing bars 23 in the flat beam 20 may be the same as the shear reinforcing bars of a normal beam, and may be equal to or greater than the minimum amount of reinforcement for the cross-sectional area of the flat beam 20 and have a desired allowable shear. The amount of reinforcement may be greater than the minimum amount of reinforcement determined from the stress.

Further, in the protruding portion 31 of the flat beam 20, U-shaped back reinforcement bars (edge crack reinforcement bars) 26 are spaced apart in the beam width direction (Y-axis direction) and between the beam main bars 21. It is located. The back reinforcement 26 corresponds to the second reinforcement of the present invention. The back surface reinforcing bars 26 are arranged on the back surface of the flat beam 20 on the outside of the column width.

Conventionally, main column reinforcement 11 is arranged within the column width at the back of the flat beam 20, but no reinforcing bars are placed outside the column width, and cracks occur on the back due to twisting due to shear force. There was a risk that The presence of the back reinforcement bars 26 makes it possible to suppress the occurrence of such cracks.

The back reinforcement 26 has a U-shape, and specifically includes a base 26a and two legs 26b extending from both ends of the base 26a. The base portion 26a is located in contact with the outer side of the end face of the beam main reinforcement 21 which is disposed at the portion closest to the rear surface of the protruding portion 31, and the respective foot portions 26b are arranged at intervals in the X-axis direction. The reinforcing bars 22 are fixed in contact with the inner sides of the upper and lower legs of the torsion reinforcing bars 22 at portions that intersect with the torsion reinforcing bars 22. The upper leg portion 26b is disposed at approximately the same height as the upper surface of the upper end reinforcement of the beam main reinforcement 21, and the lower foot portion 26b is located at approximately the same height as the lower surface of the lower end reinforcement of the beam main reinforcement 21. The end portion of each foot portion 26b on the side not connected to the base portion 26a is not particularly fixed to other reinforcing bars.

The back surface reinforcing bars 26 are inserted from the back surface of the flat beam 20 toward the inside, are arranged, and are fixed inside the flat beam 20 . It is desirable that the back reinforcing bars 26 ensure a cover thickness as a reinforcing bar and are arranged as close to the back side as possible.

However, although it is preferable to arrange the required amount of reinforcing bars 26 to resist shear force and torsion, it is preferable not to take them into account when calculating the proof strength of the flat beam 20.

Note that the present invention is not limited to the column-beam joint structure 100 specifically described in the embodiment described above, and can be modified as appropriate within the scope of the claims.

10...Column, 11...Column main reinforcement, 12...Hoop reinforcement, 20...Flat beam, 21...Beam main reinforcement, 22...Torsion reinforcement (first reinforcement), 23...Shear reinforcement (third reinforcement), 24... Stirrup (surrounding muscle), 25... Core muscle (connecting muscle), 26... Back reinforcement (second reinforcement), 26a... Base, 26b... Foot, 30... Joint, 31... Jump-out Part, 100... Column beam joint structure.

Claims (2)

A joint structure in which a column and a flat beam having a beam width wider than the column width of the column are connected such that one outer surface of each of the column and the flat beam is flush with the other side. ,
Inside the column of the column including the joint between the column and the flat beam, the flat beam is divided into two parts so as to surround a plurality of beam main reinforcements arranged in the flat beam. A plurality of first reinforcing bars each having a U-shape are fixed to the beam main reinforcement on the inside of the column width of the column, with both ends of the U-shape overlapping in the column width direction. Ori,
Out of the flat beam, on the outside of the column width of the column, the flat beam consists of a linear base extending inward from the outer surface side that is flush with the flat beam, and two legs extending from both ends of the base. U-shaped second reinforcing bars are arranged, and the two legs are respectively fixed to the first reinforcing bars at portions that intersect with the plurality of first reinforcing bars,
A plurality of third reinforcing bars are arranged in the flat beam only on the outside of the column, and the third reinforcing bars extend around the outer periphery of the plurality of beam main bars arranged in the flat beam. A column-beam joint structure comprising a surrounding reinforcement and a plurality of connecting reinforcements that connect in the direction in which the column extends in the middle of the surrounding reinforcement. Claim 1: The second reinforcing bar is characterized in that the U-shaped base is located closer to the outer surface than the first reinforcing bar closest to the flush outer surface. Column-beam joint structure described in .

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