JP2014105493A - Column head joint structure of reinforced-concrete building structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a column head joint structure which enhances earthquake-resistant strength of a column head without forming a concrete rising part.SOLUTION: In a column head joint 1, anchor hardware 18, 28, 38 are provided at upper ends of column main reinforcements 11 and tips of beam main reinforcements 21, 22 orthogonal to the column main reinforcements. The upper end of the column main reinforcement 11 is located at the position in level above the uppermost beam main reinforcement 21, and a hoop reinforcement 19 surrounding the upper end of the column main reinforcement 11 is locked to a fixed part 18 and is arranged above the beam main reinforcement 21. First reinforcement bars 41, 42 are hooked on all of the beam main reinforcements 21 at intervals in the longitudinal direction, and a second reinforcement 50 is hooked on the tips thereof. The first reinforcement bars 41, 42 are formed in a U-shape, and have hook parts 41a, 42a hooked on the beam main reinforcements 21 and downwardly extending parts 41b, 42b. The second reinforcement 50 has a rectangular loop shape, an upper side 50a thereof is hooked on the beam main reinforcement 21, left and right sides 50b thereof extend downward, and a lower side 50c thereof is arranged on the lower side of the lower side beam main reinforcement 22.

Description

  The present invention relates to a structure of a stigma opening located at a corner or a side of a reinforced concrete building such as the top floor.

  Reinforced concrete buildings have a large number of joints where the main bars of the columns intersect with the main bars of the beams extending in the two horizontal axes. The main bar of each beam includes an upper main bar and a lower main bar respectively arranged on the upper and lower horizontal planes.

  The upper end of the main bar of the pillar is arranged in the joint on the top floor of the building, and this joint is generally called the stigma. Among the stigma joints, in the joint located at the corner of the uppermost floor, the tip ends of the main bars of both beams in the biaxial direction are arranged. Since the main bars of the beams in the biaxial direction intersect, the upper main bars of both beams are shifted in the vertical direction. Similarly, the lower main bars of both beams are also displaced in the vertical direction. As a result, the upper main bar of one beam is positioned at the highest position among all the bar main bars.

In the corner head joint at the corner, the beam main bar located at the uppermost position is not constrained by other beam main bars. Therefore, if no measures are taken in this column head joint, when a large repetitive load is applied to increase or decrease the angle between the beam and the column in the event of a strong earthquake, the top beam main reinforcement covers the top of the concrete. Jump up and destroy. For this reason, the maximum value of the proof stress of the stigma is low, and sufficient deformation performance (performance for maintaining a predetermined proof strength against deformation) cannot be maintained.
The same inconvenience also occurs when the top end of the beam main bar arranged at the top is located at the stigma in the side of the top floor of the building.

In order to avoid the above inconveniences, the main bars are usually protruded largely upward from the uppermost beam main bars in the corner or side stigma. See FIG. 7 of Patent Document 1.
However, in such a structure, the concrete is swelled at a location corresponding to the stigma on the top floor, and the appearance is remarkably deteriorated.

In view of this, various ideas have been proposed in order to prevent concrete destruction due to jumping of the uppermost beam main bar without forming a raised portion of concrete.
In the stigma structure shown in FIG. 8 of Patent Document 1 as the prior art, the end of the uppermost beam main bar is bent downward, and a fixing hardware is attached to the lower end thereof. As a result, the bond strength between the uppermost beam reinforcement and the concrete below is increased, and the beam reinforcement is prevented from jumping up.
In the column head joint structure shown in FIG. 9 of Patent Document 1 as the prior art, the upper ends of the column main bars and the tip of the uppermost beam main bar are connected by a connecting bracket having an L-shaped cross section, so that these beam main bars jump. The increase is suppressed.
However, the stigma structure shown in FIGS. 8 and 9 of Patent Document 1 has poor workability.

  Therefore, Patent Document 1 proposes a stigma joint structure shown in FIG. In this stigma-type structure, the uppermost beam principal bar is constrained by reinforcing bars (indicated by reference numeral 32 in the drawing of Document 1) arranged at intervals in the longitudinal direction. This reinforcing bar is called a knurled bar, has a U-shape, and has a hanging part that is hung so as to be orthogonal to the uppermost beam main bar, and a pair of hanging parts that extend straight downward from both ends. doing.

JP 2008-240329A

  The stigma structure shown in FIG. 1 of Patent Document 1 has good workability, but as long as the inventors have tested (however, a large number of L-shaped corner reinforcing bars 30 arranged vertically and horizontally are omitted). It was tested using a test specimen), and a satisfactory maximum strength and deformation performance could not be secured.

  The present invention has been made in order to solve the above-described problem. In the joint, the upper end portion of the column main bar and the tip of the main bar of the first beam at least among the main bars of the first and second beams orthogonal to each other are provided. In the column head joint structure of a reinforced concrete building in which the upper main bar of the first beam is located at the highest position among all the beam main bars, all the upper bars of the first bar main bar and all the bars located in the joint are arranged. A fixing portion that protrudes in the radial direction of the main bars is provided at the tip of the main bar, and the upper end of the column main bar is higher than the upper main bar of the first beam, and the upper end of the main bar A hoop bar surrounding the main bar of the first beam is disposed at a position higher than the upper main bar of the first beam. The first reinforcing bars are hung on several points at intervals in the direction. In addition, a second reinforcing bar is hung on the tip part, and the first reinforcing bar has a hanging part that is hung on the upper main reinforcing bar of the first beam, and a hanging part that extends downward from the hanging part. The two reinforcing bars include a hanging portion that is hung on the upper main reinforcing bar of the first beam, a hanging portion that extends downward from the hanging portion, and a resistance applying portion that projects from the lower end portion of the hanging portion in the radial direction of the hanging portion. It is characterized by having.

  According to the above configuration, the hoop bars locked to the upper end portion of the column main bars suppress the jumping of the upper main bars of the first beam, and the first and second reinforcing bars are connected to the concrete below the upper main bars. The upper main bar is restrained by using the resistance due to the adhesion action, and the second reinforcing bar located on the most distal side also restrains the upper main bar by the resistance obtained by the resistance applying portion. It can suppress the destruction of concrete due to splashing, and can dramatically increase the maximum strength and deformation performance of the stigma.

Preferably, the second reinforcing bar is formed of a rectangular ring-shaped reinforcing bar, the upper side of which is provided as the hanging portion orthogonal to the upper main bar of the first beam, and the left and right sides thereof are provided as the hanging part, The lower side is provided as the resistance applying portion and is disposed below the lower main bar of the first beam.
According to this configuration, the lower side of the second reinforcing bar having the rectangular ring shape is arranged below the lower main bar of the first beam, and these lower main bars contribute to the restraint of the upper main bar. In particular, it is possible to suppress concrete destruction due to the upper main bar springing up.

Preferably, a plurality of the second reinforcing bars are provided, and at the four corners of one second reinforcing bar or in the vicinity thereof, the two upper main bars of the first beam and the two lower sides corresponding thereto The main bars are arranged, and the other two upper main bars of the first beam and the two lower main bars corresponding thereto are arranged at or near the four corners of the other second reinforcing bars. .
According to this configuration, more upper main bars are arranged in the vicinity of the corners of the second reinforcing bars, so that these upper main bars can be effectively restrained.

Preferably, the second reinforcing bar is made of a reinforcing bar, and the hook part, the hanging part, and a secondary hanging part that is bent from the lower end of the hanging part and is arranged below the lower main bar of the first beam. And this sub-hanging portion is provided as the fixing portion.
According to this configuration, since the sub-hanging portion of the second reinforcing bar is disposed on the lower side of the lower main bar of the first beam, these lower main bars can also contribute to restraining the upper main bar. It is possible to effectively prevent concrete destruction due to the upper main bar springing up.

Preferably, a plurality of the second reinforcing bars are provided and are individually hung on all the upper main bars of the first beam. Each second reinforcing bar has a J-shape, and the curved hanging portion, The hanging portion includes the hanging portion that extends straight downward from one end of the hanging portion, and the fixing portion that protrudes in the radial direction over the entire circumference at the lower end portion of the hanging portion, and the fixing portion is provided as the resistance applying portion. The
According to this configuration, the upper reinforcing bar of the first beam can be restrained satisfactorily using the resistance of the second reinforcing bar due to the bearing force at the fixing portion. Moreover, all the 1st, 2nd reinforcement bars can be arranged to a stigma opening from the top, and workability is good.

Preferably, the second reinforcing bar has a U-shape, the straight hanging part orthogonal to the upper main reinforcing bar of the first beam, a pair of hanging parts that extend straight downward from both ends of the hanging part, and The fixing portion protruding in the radial direction over the entire circumference of the lower end portion of the hanging portion is provided, and the fixing portion is provided as the resistance applying portion.
Even in this configuration, it is possible to satisfactorily restrain the upper main reinforcing bar of the first beam by using the resistance of the second reinforcing bar due to the support pressure at the fixing portion. Moreover, all the 1st, 2nd reinforcement bars can be arranged to a stigma opening from the top, and workability is good.

Preferably, a plurality of the U-shaped second reinforcing bars are provided, and two upper main bars of the first beam are arranged at or near two corners of one second reinforcing bar, and the other second reinforcing bars are arranged. Two other upper main bars of the first beam are arranged at or near the two corners of the two reinforcing bars.
According to this configuration, more upper main bars are arranged in the vicinity of the corners of the U-shaped second reinforcing bars, so that these upper main bars can be effectively restrained.

Preferably, the fixing portion of the second reinforcing bar is disposed at a position lower than the lower main bar of the first beam.
According to this, the adhesion strength between the concrete below the upper main reinforcing bar of the first beam and the second reinforcing bar can be increased.

Preferably, the second reinforcing bar is arranged on the tip side of the upper main bar from the fixing portion provided on the upper main bar of the first beam.
According to this, the restraining effect of the second reinforcing bar with respect to the upper main bar of the first beam can be maximized.

Preferably, the second reinforcing bars are arranged on both sides of the fixing portion provided on the upper main bar of the first beam.
According to this, the restraint of the upper main bar of the first beam by the second reinforcing bar can be further strengthened.

Preferably, the lower end of the hanging part of the first reinforcing bar is at the same height as the lower main bar of the first beam or at a lower position.
According to this, the adhesion strength between the concrete below the upper main bar of the first beam and the first reinforcing bar can be increased.

  ADVANTAGE OF THE INVENTION According to this invention, the seismic strength of a stigma joint can be raised, without forming the raised part of concrete.

It is the schematic which shows the corner part of the top floor of a reinforced concrete building, and its vicinity. It is a perspective view which shows the stigma joint structure of the corner concerning 1st Embodiment of this invention, and the main reinforcement of the 2nd beam extended in the Y-axis direction among the 1st and 2nd beam main reinforcement extended in the horizontal X and Y-axis directions Shown without. It is the side view which looked at the column head joint structure of FIG. 2 from the Y-axis direction, (A) shows the column main reinforcement and the 1st, 2nd beam main reinforcement, (B) shows the column main reinforcement and the main reinforcement of the 2nd beam. I will omit it. FIG. 3 is a side view of the stigma opening structure of FIG. 2 as viewed from the X-axis direction, in which (A) shows the column main bars and the first and second beam main bars, and (B) shows the column main bars and the second beam main bars. Show. It is a top view of the stigma opening structure of FIG. 2, (A) shows a column main reinforcement and the 1st, 2nd beam main reinforcement, (B) does not show a column main reinforcement and a 2nd beam main reinforcement. It is a side view of the apparatus which tests the seismic strength of a beam-column joint part. It is a graph which shows the seismic test result of the test body corresponding to the stigma joint structure of 1st Embodiment. It is a graph which shows the seismic test result of the test body corresponding to the structure which excluded the 1st, 2nd reinforcing bar from the stigma joint structure of 1st Embodiment for the comparison. It is a graph which shows the seismic test result of the test body corresponding to the structure which excluded the 1st reinforcement bar from the stigma joint structure of 1st Embodiment for the comparison. It is a figure equivalent to Drawing 3 (B) showing the stigma joint structure of the corner concerning a 2nd embodiment of the present invention. FIG. 4B is a view corresponding to FIG. 4B showing the stigma joint structure of the second embodiment. FIG. 5B is a view corresponding to FIG. 5B showing the stigma joint structure of the second embodiment. It is a graph which shows the seismic test result of the test body corresponding to the stigma joint structure of the second embodiment. It is a figure equivalent to Drawing 3 (B) showing the stigma joint structure of the corner concerning a 3rd embodiment of the present invention. FIG. 5B is a view corresponding to FIG. 5 (B) showing the stigma joint structure of the third embodiment. It is a graph which shows the seismic test result of the test body corresponding to the stigma joint structure of 3rd Embodiment. It is a figure equivalent to Drawing 3 (B) showing the stigma joint structure of the corner concerning a 4th embodiment of the present invention. It is a figure corresponding to Drawing 4 (B) showing the stigma joint structure of the 4th embodiment. FIG. 5B is a view corresponding to FIG. 5B showing the stigma joint structure of the fourth embodiment. It is a figure equivalent to Drawing 4 (B) showing the stigma joint structure of the corner concerning a 5th embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a stigma opening 1 located at the corner of the top floor of a reinforced concrete building. In this stigma 1, a vertical column 10 is connected to a first beam 20 and a second beam 30 that extend in the X and Y axis directions that are horizontal and orthogonal to each other.

2 to 5 show a first embodiment of the structure of the stigma 1. The column 10 includes vertical main bars 11 arranged at corners and sides of a virtual rectangular shape, and rectangular hoop bars 13 arranged at intervals in the longitudinal direction of the main bars 11 and surrounding the main bars 11. I have. The main muscle 11 and the hoop muscle 13 are connected by a wire or the like at the intersection. In addition, you may span the subband 14 between the main muscles 11 located in the side which the said rectangular shape opposes as needed.
A reinforcing bar made up of the main reinforcement 11, the hoop reinforcement 13, and the auxiliary band reinforcement 14 is embedded in the concrete 15.

The first beam 20 includes four (a plurality of) upper main bars 21 extending in the X-axis direction in parallel with each other on the same horizontal plane (indicated by reference numeral P1 in FIG. 3), and other horizontal planes below it (in FIG. 3). 4 (several) lower main reinforcing bars 22 extending in the X-axis direction in parallel with each other at a distance along the longitudinal direction of the main reinforcing bars 21 and 22. And a large number of rectangular hoop lines 23 surrounding the box. The main bars 21 and 22 and the hoop bars 23 are connected to each other at the intersections by a number line or the like. In addition, you may span the accessory band 24 between the upper principal muscle 21 and the lower principal muscle 22 as needed.
Reinforcing bar rods composed of the main bars 21 and 22, the hoop bars 23, and the auxiliary band bars 24 are embedded in concrete 25.

  Since the second beam 30 has the same configuration as the first beam 20, a detailed description thereof will be omitted. 3A, 4A, and 5A show the upper main bar 31, the lower main bar 32, and the concrete 35 of the second beam 30. FIG.

  As shown in FIG. 3A, the horizontal plane P1 on which the upper main bar 21 of the first beam 20 is arranged is located above the horizontal plane P1 'on which the upper main bar 31 of the second beam 30 is arranged. Similarly, the horizontal plane P2 on which the lower main bar 22 of the first beam 20 is arranged is located above the horizontal plane P2 'on which the lower main bar 32 of the second beam 30 is arranged. As a result, the upper main bar 21 of the first beam 20 is located at the uppermost position among all the beam main bars 21, 22, 31, 32.

  Next, the reinforcing bar structure in the stigma 1 will be described in detail. The concrete in which the reinforcing bar structure of the stigma 1 is embedded is indicated by reference numeral 5 in the figure. The upper surface of the concrete 5 is flush with the upper surfaces of the concrete 25 and 35 of the beams 20 and 30.

The main bars 11 of the column 10, the main bars 21 and 22 of the first beam 20, and the main bars 31 and 31 of the second beam 30 are orthogonal to each other at the head end 1, and the upper end of the main bar 11 and the ends of the beams 20 and 30 are perpendicular to each other. The portion is arranged in the stigma 1.
As shown in FIGS. 3A and 4A, also in the stigma 1, a plurality of hoop muscles 16 having the same shape as the above-described hoop muscles 13 are spaced apart in the longitudinal direction of the main muscles 11. Are connected.

  The upper end portion of the main bar 11 of the column 10 is located higher than the uppermost beam main bar 21. The main bar 11 is formed of a screw reinforcing bar having a screw node on the outer periphery, and a fixing metal member 18 is screwed to an upper end portion thereof. The fixing metal 18 plays a role as a fixing portion protruding in the radial direction over the entire circumference of the main bar 11, has a flange 18 a at the upper end, and constitutes a part of the main bar 11. A rectangular hoop 19 that is slightly larger than the hoop 16 surrounds the fixing metal 18 and is locked to the flange portion 18 a of the fixing metal 18. The hoop bar 19 is positioned higher than the uppermost beam main bar 21.

  As shown in FIG. 5A, when viewed from above, the main bars 21 and 22 of the first beam 20 are parallel to the two opposite sides of the hoop bars 16 and 19 of the column 10, and the inside of these two sides. The tip of the hoops 16 and 19 is not separated from the other side. The same applies to the main bars 31 and 32 of the second beam 30.

  The main bars 21, 22, 31, 32 of the beams 20, 30 are also made of screw rebars like the column main bars 11, and fixing hardware 28, 38 (fixing part) is screwed to the front ends thereof. At one end of these fixing hardware 28 and 38 (the leading end side of the beam main bar), flanges 28a and 38a are formed.

Reinforcing bars 41 and 42 (first reinforcing bars) are arranged close to each other at a plurality of places (three places in the present embodiment) at intervals in the longitudinal direction of the first beam 20 in the stigma 1. Has been. These reinforcing bars 41 and 42 are called “kiza-kushi” bars, and are formed by bending a reinforcing bar into a substantially U-shape. The linear hooking parts 41 a and 42 a and the hooking parts 41 a and 42 a from both ends downward. It has a pair of straight hanging parts 41b, 42b extending vertically.
These reinforcing bars 41 and 42 are disposed in the hoop bars 16 and 19 as viewed from above.

The hooking portion 41a of the reinforcing bar 41 is longer than the hooking portion 42a of the reinforcing bar 42, and is arranged on all the upper main bars 21 of the first beam 20 (four in this embodiment) so as to be orthogonal to the main bars 21. It is placed and connected to the main bar 21 with a wire or the like. Of the four upper main bars 21, the two upper main bars 21 positioned at the left and right ends thereof are arranged in the vicinity of two corners of the reinforcing bar 41 (intersection of the hanging portion 41a and the hanging portion 41b).
The hook portion 42 a of the reinforcing bar 42 is placed so as to be orthogonal to the central two upper main bars 21 among the four upper main bars 21, and is connected to the main bars 21. The two main reinforcing bars 21 at the center are arranged in the vicinity of the two corners of the reinforcing bars 42.

  The hanging portions 41b and 42b of the reinforcing bars 41 and 42 extend at least until the lower main bar 22 of the first beam 20 is reached.

  Further, two (a plurality of) closed reinforcing bars 50 (second reinforcing bars) are connected to the distal ends of the main bars 21 and 22 of the first beam 20 (the distal side from the reinforcing bars 41 and 42) by a line or the like. It is connected. More specifically, the fixing hardware 28 of the first beam 20 is disposed slightly apart from the tips of the main bars 21 and 22, and the reinforcing bars 50 are provided between the fixing hardware 28 and the tips of the main bars 21 and 22. Is arranged.

  As best shown in FIG. 4B, the reinforcing bar 50 is formed in a rectangular ring shape by bending a reinforcing bar and welding both ends thereof. Each reinforcing bar 50 is horizontal and has an upper side 50a (hanging part) hung orthogonally to the upper main bar 21 of the first beam 20, a left and right side 50b (hanging part) extending downward from the upper side 50a, and a lower side The lower side 50c (resistance provision part or sub-hanging part) distribute | arranged to the lower side so that the side main reinforcement 22 may be contact | connected is provided.

In the present embodiment, the two reinforcing bars 50 have the same shape and are shifted from side to side and surround the three upper main bars 21 and the three lower main bars 22, respectively. More specifically, the upper side 50a of one reinforcing bar 50 is placed on the three upper main bars 21 counted from the left among the four upper main bars 21, and the three lower main bars corresponding to the lower side 50c. 22 is disposed below.
The upper side 50a of the other reinforcing bar 50 is hung on the three upper main bars 21 counted from the right among the four upper main bars 21, and the lower side 50c is arranged below the corresponding three lower main bars 22. Has been.
Due to the arrangement of the two reinforcing bars 50 as described above, all the main bars 21 and 22 are arranged in the vicinity of the corners of one of the reinforcing bars 50.

  The diameter of the reinforcing bars 41, 42, 50 is smaller than the beam main bars 21, 22, 31, 32, and is about 70% in this embodiment (half the cross-sectional area). In the present embodiment, the total cross-sectional area of the reinforcing bars 41, 42, 50 is smaller than the total cross-sectional area of the beam main bars 21, 22, but is 50% or more.

For reference, the construction process of the stigma 1 having the above configuration will be briefly described. The column 10 is preliminarily constructed except for the column head joint 1, and the column main reinforcement 11 protrudes upward from the concrete 15. A hoop muscle 16, a fixing hardware 18, and a hoop muscle 19 are attached to the column main muscle 11. In this state, the main bars 21, 22, 31, 32 of the beams 20, 30 are arranged in the stigma 1, and the fixing hardware 28, 38 is screwed together. Further, the reinforcing bars 41 and 42 are inserted from above the stigma opening 1, and the reinforcing bars 50 are mounted from the tips of the main bars 21 and 22.
Finally, concrete 5, 25, 35 is placed on the beams 20, 30 and the stigma 1.

In the above configuration, the seismic strength of the column head joint 1 is such that the upper end portion of the column main reinforcement 11 is higher than the upper main reinforcement 21 of the first beam 20 and the hoop reinforcement 19 is arranged, and the reinforcement reinforcements 41, 42, 50 are provided. Improve dramatically by arranging the bars. The reason will be described below.
When the building receives a repeated load in the direction of increasing or decreasing the angle between the column 10 and the first beam 20 due to a strong earthquake, the upper main bar 21 of the first beam 20 jumps up the concrete 5 above the column head joint 1. Try to. However, in this embodiment, the upper end of the column main reinforcement 11 is at a position higher than the upper main reinforcement 21, and the hoop muscle 19 locked to the upper end suppresses the upper main reinforcement 21 from jumping up, the reinforcement reinforcement 41, 42 and 50 constrain the upper main bar 21 by adhesion resistance between the hanging parts 41b, 42b and 50b and the concrete 5 below the upper main bar 21, and the lower main bar 22 also via the lower side 50c of the reinforcing bar 50 By contributing to the restraint of the upper main reinforcement 21, it is possible to prevent the concrete 5 above the upper main reinforcement 21 from being broken and to increase the seismic strength of the stigma 1. In other words, the column head joint 1 can realize a high maximum proof stress without large breakage, and can allow a large increase / decrease in the angle between the column 10 and the beam 20 while maintaining a proof stress of a predetermined value or more (deformation). High performance).

  In order to confirm the seismic strength of the columnar joint structure having the above configuration, as shown in FIG. 6, a positive and negative alternating incremental load test of an L-shaped specimen T corresponding to this columnar joint structure was performed. This test body T does not include the second beam 30, but includes a joint 1 '(corresponding to the column head opening 1) connecting the column 10 and the first beam 20.

  The apparatus used for the test includes a horizontal hydraulic cylinder 100, a vertical hydraulic cylinder 110, a column support 120, and a beam support 130. The base end of the horizontal hydraulic cylinder 100 is rotatably connected to a fixed base 140 fixed to a vertical wall, and the base end of the vertical hydraulic cylinder 110 is rotatable to a fixed base 150 fixed to the floor. It is connected to. The column support 120 is rotatably connected to the tip of the rod portion of the hydraulic cylinders 100 and 120. The beam support base 130 is rotatably connected to a fixed base 160 fixed to the floor.

  The test body T is set by horizontally setting the column 10 and fixing the end of the column 10 to the column support 120, fixing the first beam 20 vertically and fixing the end of the beam 20 to the beam support 130. Set in test equipment.

  In the set state, a positive / negative alternating load is applied by the horizontal hydraulic cylinder 100, and this alternating load is gradually increased. The vertical hydraulic cylinder 110 is controlled to keep the height of the column support 120 constant. As a result, the bending strength of the beam 20 including the joint 1 'can be measured.

The test results are shown in the graph of FIG. In this graph, the vertical axis represents the load (unit: kN) by the horizontal hydraulic cylinder 100, where the load in the direction of decreasing the angle of the joint 1 ′ is positive, and the load in the direction of increasing the angle is negative. The horizontal axis represents the interlayer deformation angle R (unit: rad). This interlayer deformation angle R can be expressed by the following equation.
R = δ / L
However, L is the distance between the rotation fulcrum of the beam 20 and the center of the joint 1 ′ as shown in FIG. 6, and δ is the horizontal displacement of the center of the joint 1 ′.

  Furthermore, the graph of FIG. 7 shows the calculated value of beam bending strength, 80% strength, and limit deformation angle. The calculation value of the beam bending strength is the bending strength required for the beam 20 of the test body as a minimum. 80% yield strength means a yield strength of 80% of the maximum strength, and is the minimum required yield strength at the limit deformation angle. The limit deformation angle is 0.04 rad in this embodiment.

As is apparent from the graph of FIG. 7, the test body T corresponding to the present embodiment has a maximum bending strength exceeding the calculated value of the beam bending strength, the bending strength at the limit deformation angle also exceeds 80% strength, Even when the interlayer deformation angle increases, a high bending strength is maintained. That is, the maximum proof stress is high and the deformation performance is also excellent.
For comparison, a test was performed using a test body corresponding to a stigma-type structure without the reinforcing bars 41, 42 and 50, and the results shown in the graph of FIG. 8 were obtained. As is apparent from this graph, the bending strength of the test specimen is less than the calculated value of the beam bending strength, and the yield strength at the limit deformation angle is far below 80% strength.

  For further comparison, a test was performed using only the reinforcing bar 50 and a test body corresponding to the stigma joint structure in which the reinforcing bars 41 and 42 were omitted, and the results shown in the graph of FIG. 9 were obtained. As is clear from this graph, the bending strength of the specimen exceeds the calculated value of the beam bending strength, but the yield strength at the limit deformation angle is less than 80%.

Hereinafter, other embodiments of the present invention will be described with reference to the drawings. In these embodiments, components corresponding to the preceding embodiments are given the same reference numerals in the drawings, and detailed descriptions thereof are omitted.
10 to 12 show a stigma structure that constitutes a second embodiment of the present invention. In these drawings, the main bars 11 and the hoop bars 13, 16, 19 and the like of the column 10 are not shown, and the main bars 31, 32 and the like of the second beam 30 are also not shown.

In the second embodiment, the second reinforcing bars 60 are separately hung on all the upper main bars 21 of the first beam 20. The second reinforcing bar 60 includes a screw reinforcing bar 61 and a fixing hardware 62 (fixing part, resistance applying part). The screw rebar 61 is called a stick stick, is bent into a J-shape, and is hook-shaped hook 61a hung on the tip of the upper main bar 21 (between the tip of the upper main bar 21 and the fixing hardware 28). And a hanging portion 61b that extends straight downward from one end of the hanging portion 61a. The fixing metal 62 is screwed to the lower end portion of the hanging portion 61. The fixing hardware 62 is located at a position lower than the lower main bar 22.
In this embodiment, the resistance to supporting pressure at the fixing hardware 62 is applied to the second reinforcing bar 60 to help restrain the upper main bar 21.

  When a test similar to that of the first embodiment was performed using an L-shaped test body corresponding to the stigma structure of the second embodiment, the result shown in the graph of FIG. 13 was obtained. As is apparent from this graph, the specimen has a bending strength exceeding the calculated value of the beam bending strength, and the bending strength at the limit deformation angle also exceeds 80%. However, the deformation performance is inferior to that of the first embodiment.

  14 and 15 show a stigma structure that constitutes a third embodiment of the present invention. In the third embodiment, the second reinforcing bars 60 of the second embodiment are arranged on both sides of the fixing hardware 28 at the tip of each upper main bar 21.

  When a test similar to that of the first embodiment was performed using an L-shaped test body corresponding to the stigma structure of the third embodiment, the result shown in the graph of FIG. 16 was obtained. As is apparent from this graph, the deformation performance was further improved compared to the second embodiment, and a deformation performance comparable to that of the first embodiment was obtained.

  Next, a stigma structure that constitutes a fourth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, two second reinforcing bars 70 </ b> A and 70 </ b> B are hung on the tip of the upper main bar 21 (between the tip of the upper main bar 21 and the fixing hardware 28). These reinforcing bars 70A and 70B have a screw reinforcing bar 71 and two fixing hardware 72 (fixing part, resistance applying part). The screw rebar 71 is referred to as a shaving bar, is bent in a U shape, and is a straight hanging portion 71a that is hung orthogonally to the upper main reinforcement 21, and extends straight downward from both ends of the hanging portion 71a. It has a pair of hanging parts 71b. The fixing metal 72 is screwed to the lower end portion of the hanging portion 71b. The fixing hardware 72 is at a position lower than the lower main reinforcement 22.

The hooks 71a of the reinforcing bars 70A are longer than the hooks 71a of the reinforcing bars 70B, and are arranged on all (four in this embodiment) upper main bars 21 of the first beam 20 so as to be orthogonal to the main bars 21. It is placed and connected to the main bar 21 with a wire or the like. Of the four upper main bars 21, the upper main bars 21 located at the left and right ends thereof are arranged in the vicinity of the corners of the reinforcing bars 41 (intersections between the hanging parts 71a and the hanging parts 71b).
The hook portion 71 a of the reinforcing bar 70 </ b> B is placed so as to be orthogonal to the central two upper main bars 21 among the four upper main bars 21, and is connected to these main bars 21. These two main bars 21 at the center are arranged in the vicinity of the corners of the reinforcing bar 70B.

  The fourth embodiment is expected to have the same proof stress as the second embodiment. Similarly to the third embodiment, the second reinforcing bars 70A and 70B may be arranged on both sides of the fixing hardware 28.

Next, a stigma structure that constitutes a fifth embodiment of the present invention will be described with reference to FIG. In this embodiment, it is formed by bending a reinforcing bar, and a straight hanging part 80b, a hook-shaped hanging part 80a connected to the upper end of the hanging part 80b, and a hook-shaped auxiliary hanging part 80c connected to the lower end of the hanging part 80b. (Resistance provision part).
The hanging portion 80 a is hung on the upper main bar 21 of the first beam 20, and the sub hanging portion 80 c is hung on the lower main bar 22.
In the fifth embodiment, since the lower main reinforcement 22 contributes to the restraint of the upper main reinforcement 21, the same maximum proof stress and deformation performance as in the first embodiment are expected.

  The above-mentioned stigma structure can be applied not only to the corner of the top floor of the building shown in FIG. 1, but also to the stigma 1A of the side of the top floor. In this case, the main bar of the second beam 30 penetrates the stigma 1A, so that the end portion is not located at the stigma 1A. Therefore, it is not necessary to provide a fixing hardware (fixing portion) on the main bar of the second beam 30 in the stigma 1A.

The present invention is not limited to the above embodiment, and various forms can be adopted. For example, in the first embodiment, the second reinforcing bar having a rectangular ring shape may be bent on a common beam main bar by bending into a hook shape without welding both ends of the reinforcing bar.
Moreover, you may use the 2nd reinforcement bar of a different size in 1st Embodiment. That is, one large sized second reinforcing bar surrounds the four upper main bars and the four lower main bars, and the upper main bars at the left and right ends and the lower main bars at both the left and right ends are located at or near the four corners. To be placed. The other small second reinforcing bar surrounds the middle two upper main bars and the middle two lower main bars so that the central main bars are arranged at or near the four corners. .
In the first embodiment, one second reinforcing bar may be used. In this case, the second reinforcing bars surround the four upper main bars and the four lower main bars, and the upper main bars at both ends and the lower main bars at both ends are arranged at or near the four corners.

The fixing metal may be fixed by filling a filler between the fixing metal and the reinforcing bar without using screwing.
The fixing portion of the column main bar, the beam main bar, and the reinforcing bar may be a reinforced knot formed by cold or hot working.

The first reinforcing bar may be formed of a stick muscle.
You may form a fixing | fixed part also in the lower end part of the drooping part of a 1st reinforcement bar.

  The present invention can be applied to the top-cap structure of the top floor of a reinforced concrete building.

1,1A Pillar joint 10 Pillar 11 Pillar main reinforcement 18 Fixing hardware (fixing part)
19 Hoop muscle 20 First beam 21 Upper principal muscle (uppermost principal muscle)
22 Lower main bar 28 Fixing hardware (fixing part)
30 Second beam 31 Upper main bar 32 Lower main bar 38 Fixing hardware (fixing part)
41, 42 1st reinforcement bar 41a, 42a Hanging part 41b, 42b Hanging part 50 2nd reinforcement bar 50a Upper side (hanging part)
50b Left and right sides (lower part)
50c Lower side (resistance applying part, secondary hanging part)
60, 70A, 70B Second reinforcing bars 61a, 71a Hanging portions 61b, 71b Hanging portions 62, 72 Fixing hardware (fixing portion, resistance applying portion)
80 Second reinforcing bar 80a Hanging portion 80b Hanging portion 80c Sub hanging portion (resistance applying portion)

Claims (11)

In the joint, the upper end of the column main bar and the tip of the main bar of at least the first beam among the main bars of the first and second beams orthogonal to each other are arranged, and the upper main bar of the first beam In the stigma structure of a reinforced concrete building located at the top of the main bars,
A fixing portion protruding in the radial direction of these main bars is provided at the upper end of the column main bars and at the tip of all beam main bars located in the joint,
An upper end portion of the column main bar is positioned higher than an upper main bar of the first beam, and a hoop bar surrounding the upper end portion of the column main bar is locked to a fixing portion of the column main bar so that the upper side of the first beam is higher. Placed higher than the main muscle,
In the joint, all of the upper main reinforcing bars of the first beam are hung with a first reinforcing bar at a plurality of positions at intervals in the longitudinal direction, and a second reinforcing bar is hung at the tip thereof,
The first reinforcing bar has a hanging part hung on the upper main reinforcing bar of the first beam, and a hanging part extending downward from the hanging part,
The second reinforcing bar includes a hanging portion that is hung on the upper main reinforcing bar of the first beam, a hanging portion that extends downward from the hanging portion, and a resistance applying portion that protrudes in a radial direction from the lower end portion of the hanging portion to the hanging portion. A stigma structure characterized by having   The second reinforcing bar is made of a rectangular ring-shaped reinforcing bar, the upper side of which is provided as the hanging portion orthogonal to the upper main bar of the first beam, the left and right sides thereof are provided as the hanging portion, and the lower side is 2. The stigma opening structure according to claim 1, wherein the stigma opening structure is provided as the resistance applying portion and is disposed below the lower main reinforcement of the first beam.   A plurality of the second reinforcing bars are provided, and two upper main bars of the first beam and two corresponding lower main bars are arranged at or near the four corners of one second reinforcing bar. And the other two upper main bars of the first beam and the two lower main bars corresponding thereto are arranged at or near the four corners of the other second reinforcing bars. The stigma structure according to claim 2.   The second reinforcing bar is made of a reinforcing bar, and has the hanging part, the hanging part, and a secondary hanging part that is bent from the lower end of the hanging part and is arranged below the lower main reinforcing bar of the first beam. The stigma structure according to claim 1, wherein the sub-hanging portion is provided as the resistance applying portion.   A plurality of the second reinforcing bars are provided and are separately hung on all upper main bars of the first beam. Each second reinforcing bar has a J-shape, the curved hanging portion, and the hanging portion of the hanging portion. The drooping portion extending straight downward from one end, and the fixing portion protruding in the radial direction over the entire circumference at the lower end portion of the drooping portion, and the fixing portion is provided as the resistance applying portion. The stigma structure according to claim 1, wherein   The second reinforcing bar is U-shaped, the straight hanging part orthogonal to the upper main reinforcing bar of the first beam, a pair of hanging parts extending straight downward from both ends of the hanging part, and the hanging parts 2. The stigma structure according to claim 1, further comprising: a fixing portion that protrudes in a radial direction over the entire circumference at a lower end portion, and the fixing portion is provided as the resistance applying portion.   A plurality of the U-shaped second reinforcing bars are provided, and two upper main bars of the first beam are arranged at or near two corners of one second reinforcing bar, and the other second reinforcing bars. 7. The stigma opening structure according to claim 6, wherein the other two upper main bars of the first beam are arranged at or near the two corners.   The stigma opening structure according to any one of claims 5 to 7, wherein the fixing portion of the second reinforcing bar is disposed at a position lower than the lower main bar of the first beam.   The stigma according to any one of claims 1 to 8, wherein the second reinforcing bar is arranged on a distal end side of the upper main bar from the fixing portion provided on the upper main bar of the first beam. Joint structure.   9. The stigma opening structure according to claim 5, wherein the second reinforcing bars are arranged on both sides of the fixing portion provided on the upper main bar of the first beam.   11. The stigma structure according to claim 1, wherein a lower end of a hanging portion of the first reinforcing bar is at a level equal to or lower than a lower main bar of the first beam.

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