JP7018608B2 - Beam opening reinforcement structure - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act 2017 Conference (China) Academic Lecture Abstracts / Architectural Design Presentation Abstracts DVD (Published: July 20, 2017)

The present invention relates to a beam opening reinforcing structure for reinforcing a peripheral portion of a reinforced concrete beam opening in a building.

Reinforced concrete foundation beams extending in the horizontal direction are provided in reinforced concrete structures and the like. This foundation beam may be opened by penetrating in the width direction of the foundation beam and having a circular cross section so that a person can pass through for maintenance, inspection, etc. of equipment piping. The hole may be required to have a size that allows people, equipment, etc. to pass through. Such an opening is called a "traffic hole".

However, when the opening is formed in the foundation beam, the strength of the foundation beam is lowered, and in particular, the ultimate shear strength of the foundation beam is lowered. In addition, cracks are likely to occur in the peripheral portion of the opening of the foundation beam due to stress concentration. Therefore, in order to secure sufficient strength of the foundation beam, it is desirable that the diameter of the opening is 1/3 or less of the height of the foundation beam, that is, the beam diameter, in other words, the beam diameter. Is desirable to be at least 3 times the diameter of the opening. Further, in order to reinforce the peripheral portion of the opening of the foundation beam, a reinforcing bar may be installed around the opening in the inside of the foundation beam. (See, for example, Non-Patent Document 1.)

For example, the reinforcing bar may be a horizontal reinforcing bar (without hook type) that extends linearly along the longitudinal direction of the foundation beam and is arranged above and below the opening. In such a horizontal reinforcing bar, both ends extending from both ends in the longitudinal direction of the central portion arranged in accordance with the opening in the longitudinal direction of the foundation beam are fixed (so-called linear fixing). There is.

Generally, it is desirable to secure the fixing length under such conditions at least 35 times the diameter of the reinforcing bar of the reinforcing bar used for fixing. (For example, refer to Non-Patent Document 2.) Therefore, it is desirable to secure the length of each end of the horizontal reinforcing bar at least 35 times the diameter of the reinforcing bar.

Reinforced concrete structure calculation standard and commentary, 8th edition, Architectural Institute of Japan, May 20, 1971, pp. 354-355 Ministry of Land, Infrastructure, Transport and Tourism Minister's Office Repair Department, Public Works Standard Specifications (Building Works) 2016 Edition, March 31, 2016, pp. 28-29

However, in the above-mentioned foundation beam, the beam is provided under the condition that the size of the opening is secured so that people, equipment, etc. can pass through it, and the beam length is 3 times or more the diameter of the opening. However, it is determined based on the diameter of the opening, not the cross-sectional dimensions determined based on structural calculations. In this case, the beam sill increases due to the partial opening, and the foundation beam becomes large. This is not preferable because it leads to an increase in the construction cost of the building.

Further, in a reinforced concrete building, it may be desired to shorten the length of the reinforcing bar, particularly the length of fixing the reinforcing bar, from the viewpoint of making the reinforcing bar easier to handle, reducing the material of the reinforcing bar, and the like. .. Therefore, even in the horizontal reinforcing bar provided around the opening of the foundation beam, especially when it is desired to provide another opening in the vicinity of the position where the horizontal reinforcing bar is fixed, the length of the fixing, that is, each end portion. It may be desirable to shorten the length of the.

Therefore, in the beam opening reinforcement structure that reinforces the peripheral part of the beam opening of the reinforced concrete in the building, the beam is prevented from becoming large while efficiently ensuring the strength of the beam, and is provided in the peripheral part of the beam opening. It is desired to shorten the anchoring length of the horizontal reinforcing bars.

In order to solve the above problems, the beam opening reinforcement structure according to one aspect penetrates the reinforced concrete beam arranged along the horizontal direction of the building in the width direction and has a circular or polygonal cross section. It is a beam opening reinforcement structure configured to reinforce the peripheral portion of the opening of the beam by forming the opening to have, and surrounds the plurality of main bars extending in the longitudinal direction of the beam and the opening. The opening reinforcing member arranged in the above, the upper and lower horizontal reinforcing bars extending linearly in the longitudinal direction and arranged on the upper and lower sides of the opening, respectively, and the upper horizontal reinforcement. An upper opening reinforcing bar that surrounds the muscle and is arranged above the opening, and a lower opening that surrounds the lower horizontal reinforcing bar and is arranged below the opening. Reinforcing bars and the plurality of reinforcing bars on the left and right sides of the plurality of main bars, which surround the upper region of the beam and are arranged on the left and right sides in the longitudinal direction with respect to the opening, respectively. On the left and right sides of the main bar, which surrounds the lower region of the beam and is arranged on the left outer side and the right outer side of the hole reinforcing bar on the side away from the opening in the longitudinal direction, respectively. The beam is provided with a shear reinforcing bar, the height of the beam is 2.5 times or more and less than 3 times the diameter of the opening, and various horizontal reinforcing bars are provided in the longitudinal direction in accordance with the opening. It has a central part to be arranged and both ends arranged on both sides in the longitudinal direction with respect to the central part, and both ends of various horizontal reinforcing bars are fixed, and the length of various horizontal reinforcing bars can be adjusted. Let L be, the diameter of the cross section of the opening be D, the diameter of the reinforcing bars of various horizontal reinforcing bars be d, the predetermined coefficient be α, and the lengths of the various horizontal reinforcing bars are based on the following (Equation 1). D is 500 mm to 750 mm, d is equal to or greater than the diameter of the reinforcing bars at the various holes and equal to or less than the diameter of the reinforcing bars of the main reinforcement, and α is 14.4 to 21.

L = D + 2 × α × d ・ ・ ・ (Equation 1)

According to the beam opening reinforcement structure according to the above aspect, it is possible to prevent the beam from becoming large while efficiently ensuring the strength of the beam, and the horizontal reinforcing bars provided around the beam opening can be fixed. The length can be shortened.

It is a front view which shows typically the beam which has the beam opening reinforcement structure which concerns on this embodiment. FIG. 3 is a cross-sectional view taken along the line AA of FIG. It is sectional drawing BB of FIG. It is a cross-sectional view taken along the line CC of FIG. It is a side view which shows in the state that the upper opening reinforcing bar which concerns on this embodiment is disassembled. It is a side view which shows typically the deformation example of the upper opening reinforcing bar which concerns on this embodiment. It is a side view which shows the modified example of the upper opening reinforcing bar which concerns on this embodiment in the disassembled state.

The beam opening reinforcement structure according to this embodiment will be described below.

As shown in FIGS. 1 to 4, the beam opening reinforcing structure 2 according to the present embodiment is provided on the reinforced concrete beam 1 of the building. The beam 1 is arranged along the horizontal direction of the building. In particular, the beam 1 may extend substantially linearly along the horizontal direction, and the beam 1 may have a substantially quadrangular cross section. The beam 1 is also preferably a foundation beam configured as a horizontal member connecting the foundations (not shown) under the columns of the building.

The beam 1 is made of a concrete material and has a concrete portion 11 that forms the outer shape of the beam 1. In FIGS. 1 to 4, the concrete portion 11 and the component of the beam 1 composed of the concrete portion 11 are shown by a two-dot chain line. Further, the inside of the beam 1 is assumed to mean a portion covered by the concrete portion 11. The concrete material used for such a concrete portion 11 may be ordinary concrete, high-strength concrete, or the like. According to this embodiment, even when the concrete material is ordinary concrete, the strength of the beam opening reinforcing structure 2 can be sufficiently obtained.

As shown in FIGS. 1 and 2, the beam 1 also has an opening 1a penetrating in the width direction of the beam 1 (hereinafter, simply referred to as “width direction” if necessary). The cross section of the opening 1a is formed in a substantially circular shape. The opening 1a is formed in a size that allows people, equipment, and the like to pass through, and specifically, the diameter D of the opening 1a is about 500 mm to about 750 mm. The cross section of the opening may be formed in a substantially polygonal shape, and in this case, the diameter of the circumscribed circle of the opening may be defined as the diameter of the opening.

As shown in FIGS. 1 to 4 again, in such a beam 1, the beam opening reinforcing structure 2 reinforces the opening peripheral portion 1b located around the opening 1a. In the beam 1 according to the present embodiment, one side of the beam 1 in the longitudinal direction (hereinafter, simply referred to as “longitudinal direction” as necessary) with respect to the perforated portion 1b of the opening, that is, the left side (according to the arrow V1). The portion located on the left side general portion 1c is referred to as a left side general portion 1c, and the portion located on the other side in the longitudinal direction with respect to the opening peripheral portion 1b, that is, the portion located on the right side (indicated by the arrow V2) is referred to as a right side general portion 1d.

The beam opening reinforcement structure 2 includes a plurality of main bars 21 extending in the longitudinal direction straddling the opening peripheral portion 1b and the left and right general portions 1c and 1d inside the beam 1, and the inside of the opening peripheral portion 1b of the beam 1. It is provided with an opening reinforcing member 22 arranged so as to surround the opening 1a.

The beam opening reinforcing structure 2 is also provided inside the upper and lower horizontal reinforcing bars 23 and 24 extending linearly in the longitudinal direction inside the opening peripheral portion 1b of the beam 1 and inside the opening peripheral portion 1b of the beam 1. It is provided with upper and lower opening reinforcing bars 25 and 26 surrounding the upper and lower horizontal reinforcing bars 23 and 24, respectively. The upper horizontal reinforcing bar 23 and the upper opening reinforcing bar 25 are arranged above the opening 1a, and the lower horizontal reinforcing bar 24 and the lower opening reinforcing bar 26 are arranged below the opening 1a. ..

Further, the beam opening reinforcement structure 2 surrounds at least a part of the plurality of main bars 21 inside the opening peripheral portion 1b of the beam 1, and is indicated by one side in the longitudinal direction with respect to the opening 1a (arrow V1). ), Which surrounds at least a part of the left outer and left inner hole reinforcements 27 and 28 and the plurality of main bars 21, and is longitudinal with respect to the opening 1a inside the opening peripheral portion 1b of the beam 1. It is provided with right outer and right inner hole reinforcements 29, 30 arranged on the other side of the direction (indicated by the arrow V2). The left and right lateral aperture reinforcing bars 27 and 29 extend inside the beam 1 along the outer peripheral edge of the beam 1. The left and right inner hole reinforcements 28 and 30 are located inside the left and right outer hole reinforcements 27 and 29, respectively, in the width direction.

The beam opening reinforcement structure 2 is arranged inside the left general portion 1c of the beam 1 on one side in the longitudinal direction (indicated by the arrow V1) with respect to the left outer and left inner hole reinforcements 27 and 28. On the other side (indicated by arrow V2) in the longitudinal direction with respect to the left outer and left inner shear reinforcing bars 31 and 32 and the right outer and right inner hole reinforcements 29 and 30, the right general portion 1d of the beam 1 It is provided with right outer and right inner shear reinforcing bars 33 and 34 arranged inside. The left and right outer shear reinforcing bars 31, 33 extend along the outer peripheral edge of the beam 1 inside the beam 1. The left and right inner shear reinforcing bars 32 and 34 are located inside the left and right outer shear reinforcing bars 31 and 33 in the width direction, respectively.

The beam opening reinforcement structure may be a structure having no reinforcing bars near the left and right inner holes. However, in particular, from the viewpoint of efficiently reinforcing the beam 1 having the opening 1a, particularly the peripheral portion 1b of the opening, the beam opening reinforcing structure 2 is added to the left and right outer aperture reinforcing bars 27 and 29. It is preferable to have reinforcing bars 28 and 30 near the left and right inner holes. Further, the beam opening reinforcing structure may be a structure having no left and right inner shear reinforcing bars. However, in particular, from the viewpoint of efficiently reinforcing the beam 1 having the opening 1a, the beam opening reinforcing structure 2 includes the left and right inner shear reinforcing bars 32 and 34 in addition to the left and right outer shear reinforcing bars 31 and 33. It is preferable to have it. Furthermore, from the viewpoint of efficiently reinforcing the peripheral portion of the hole, the beam opening reinforcement structure has the left and right inner hole reinforcements in addition to the left and right outer hole reinforcements, while the left and right outer shear reinforcements. In addition, the structure may have no left and right inner shear reinforcing bars.

In such a beam opening reinforcing structure 2, the main bar 21, the opening reinforcing member 22, and various reinforcing bars 23 to 34 are manufactured by using a reinforcing bar material such as round steel or deformed bar steel. Further details of the beam opening reinforcing structure 2 will be described below.

[Details of the main line]
The details of the main bar 21 will be described. In the present embodiment, as shown in FIGS. 2 to 4, the beam opening reinforcing structure 2 includes 16 main bars 21. Inside the beam 1, four main bar rows including the four main bar 21, that is, the first to fourth main bar rows R1 to R4 are arranged in order from the upper side to the lower side. The first to fourth main muscle rows R1 to R4 are located at intervals in the vertical direction from each other. The four main bars 21 of each main bar row R1 to R4 are arranged so as to be spaced apart from each other in the width direction. Hereinafter, if necessary, the four main bars of each main bar row are referred to as first to fourth main bars in order from the front side (indicated by the arrow W1) in the width direction to the other side (indicated by the arrow W2).

The first and second main muscle rows R1 and R2 are arranged in the upper region 1e of the beam 1 located above the opening 1a. Specifically, the first main bar row R1 is arranged along the upper surface of the beam 1 in the upper region 1e. The second main muscle row R2 is arranged between the first main muscle row R1 and the vertical center of the upper region 1e. The third and fourth main muscle rows R3 and R4 are arranged in the lower region 1f of the beam 1 located below the opening 1a. Specifically, the third main bar row R3 is arranged along the lower surface of the beam 1 in the lower region 1f. The fourth main muscle row R4 is arranged between the vertical center of the lower region 1f and the third main muscle row R3.

The first main bar 21 of the first main line R1 is located between the first and second main lines 21 of the second main line R2 in the width direction. The second and third main bars 21 of the first main line R1 are located between the second and third main bars 21 of the second main line R2 in the width direction. The fourth main bar 21 of the first main line R1 is located between the third and fourth main lines 21 of the second main line R2 in the width direction.

The first main bars 21 of the second and third main bar rows R2 and R3 are arranged along the front surface of the beam 1. The second main bars 21 of the second and third main bar rows R2 and R3 are arranged in the vertical direction. The third main bar 21 of the second and third main bar rows R2 and R3 is also arranged in the vertical direction. The fourth main bar 21 of the second and third main bar rows R2 and R3 is arranged along the back surface of the beam 1.

The first main bar 21 of the fourth main line R4 is located between the first and second main lines 21 of the third main line R3 in the width direction. The second and third main bars 21 of the fourth main line R4 are located between the second and third main bars 21 of the third main line R3 in the width direction. The fourth main bar 21 of the fourth main line R4 is located between the third and fourth main lines 21 of the third main line R3 in the width direction.

In the present embodiment, it is preferable that the reinforcing bar material used for each main bar 21 is the same. For example, the reinforcing bar material may be round steel or deformed steel bar specified in JIS G 3112, or deformed steel bar of about 980 N / mm class ² .

However, the main line is not limited to the above, and may be as follows. The number of main bars does not have to be 16, and may be appropriately determined according to the structure of the beam, the strength of the beam, and the like. Inside the beam, five or more main bars may be arranged in order from top to bottom. Further, each main muscle row may include at least two main muscles.

[Details of opening reinforcement member]
The details of the opening reinforcing member 22 will be described. In the present embodiment, as shown in FIG. 2, the beam opening reinforcing structure 2 includes three opening reinforcing members 22. The three opening reinforcing members 22 are arranged side by side with a space between them in the width direction. In particular, it is preferable that the three opening reinforcing members 22 are arranged at equal intervals in the width direction. Hereinafter, if necessary, the three opening reinforcing members will be referred to as first to third opening reinforcing members in order from the front side (indicated by the arrow W1) to the back side (indicated by the arrow W2) in the width direction. ..

The first opening reinforcing member 22 is arranged along the front surface of the beam 1. The second opening reinforcing member 22 is arranged substantially at the center of the beam 1 in the width direction. The third opening reinforcing member 22 is arranged along the back surface of the beam 1.

With reference to FIGS. 1 and 2, the preferred shape of each opening reinforcing member 22 will be described below. The three opening reinforcing members 22 are formed in substantially the same shape. Each opening reinforcing member 22 has an inner ring bar 22a formed so as to surround the opening 1a and an outer ring bar 22b formed so as to surround the inner ring bar 22a. The inner ring bar 22a may extend in a substantially square shape, particularly a substantially square shape, and the outer ring bar 22b may extend in a substantially octagonal shape. In this case, the inner ring bar 22a is arranged so that the pair of diagonal portions are along the vertical direction, and the outer ring bar 22b is arranged so that the pair of opposite side portions are along the vertical direction. It is preferable that the pair of diagonal portions of the inner ring bar 22a as described above are welded to the pair of diagonal portions of the inner ring bar 22a, respectively. Further, from the viewpoint of preventing cracks extending from the opening 1a at the peripheral portion 1b of the opening, particularly from the viewpoint of suppressing the width of the cracks, the diameter of the reinforcing bar of the inner ring bar 22a is larger than the diameter of the reinforcing bar of the outer ring bar 22b. It should be bigger.

In the present embodiment, the reinforcing bar materials used for the three opening reinforcing members 22 are the same. The diameter of the reinforcing bar of the reinforcing bar material used for the opening reinforcing member 22 is preferably equal to or larger than the diameter of the reinforcing bar of the reinforcing bar material used for the various hole-side reinforcing bars 27 to 30. For example, such a reinforcing bar material may be a reinforcing bar material such as a deformed steel bar specified in JIS G 3112 such as SD295A and SD345, or a reinforcing bar material such as a high-strength deformed steel bar of about 785 N / mm class ² . .. Further, the reinforcing bar material used for the hole-opening reinforcing member 22 is preferably one having a strength equal to or higher than the strength of the reinforcing bar material used for the various hole-side reinforcing bars 27 to 30.

However, the opening reinforcing member is not limited to the above, and may be as follows. The number of opening reinforcement members may be set to two or more depending on the structure of the beam, the strength of the beam, etc., and the beam opening reinforcement structure has two openings arranged along the front surface and the back surface of the beam, respectively. It suffices to have at least a hole reinforcing member. The inner ring bar and the outer ring bar of the perforation reinforcing member may be formed in a single stroke using one continuous reinforcing bar material, and in this case, the reinforcing bar material used for the perforation reinforcing member is particularly high. It may be KSS785 or MK785. The perforation reinforcing member may have intermediate ring bars located between the inner and outer ring bars, in which case it is preferred that the intermediate ring bars extend in a substantially octagonal shape. The shape of at least one of the plurality of perforated reinforcing members may be different from the shape of the rest of the plurality of perforated reinforcing members. At least one of the plurality of perforated reinforcing members may be different from the remaining rebar material of the plurality of perforated reinforcing members.

It is particularly preferable that the opening reinforcing member 22 is a dialene (registered trademark) or dialene NS manufactured by Koryo Kenpan Co., Ltd.

[Details of horizontal reinforcement]
The details of the upper and lower horizontal reinforcing bars 23 and 24 will be described. In the present embodiment, as shown in FIG. 2, the beam opening reinforcing structure 2 includes two upper horizontal reinforcing bars 23 and two lower horizontal reinforcing bars 24. The number of upper horizontal reinforcing bars 23 is preferably the same as the number of lower horizontal reinforcing bars 24.

The two upper horizontal reinforcing bars 23 are arranged along the front surface and the back surface in the width direction of the beam 1, respectively. The two lower horizontal reinforcing bars 24 are also arranged along the front and back of the beam 1, respectively. Further, various horizontal reinforcing bars 23 and 24 along the front surface of the beam 1 are located corresponding to the first opening reinforcing member 22 in the width direction. Various horizontal reinforcing bars 23, 24 along the back surface of the beam 1 are also located corresponding to the third opening reinforcing member 22 in the width direction. The upper horizontal reinforcing bar 23 is located between the opening 1a and the upper end of each opening reinforcing member 22 in the vertical direction, and the lower horizontal reinforcing bar 24 is located between the opening 1a and each opening in the vertical direction. It is located between the lower end of the hole reinforcing member 22 and the lower end.

As shown in FIG. 1, each of the horizontal reinforcing bars 23, 24 has a central portion 23a, 24a arranged in the longitudinal direction in accordance with the opening 1a, and one side in the longitudinal direction with respect to the central portions 23a, 24a. It has one end 23b, 24b arranged (indicated by arrow V1) and the other end 23c, 24c arranged on the other side (indicated by arrow V2) in the longitudinal direction with respect to the central 23a, 24a. .. Both ends 23b, 23c, 24b, 24c in the longitudinal direction of the horizontal reinforcing bars 23, 24 are not formed in a hook shape, and the horizontal reinforcing bars 23, 24 are horizontal reinforcing bars without hooks. One end 23b, 24b and the other end 23c, 24c of each of the horizontal reinforcing bars 23, 24 are fixed.

It is preferable that the reinforcing bar materials used for such various horizontal reinforcing bars 23 and 24 are the same. Further, the reinforcing bar diameter of the reinforcing bar material used for the various horizontal reinforcing bars 23 and 24 is preferably larger than the reinforcing bar diameter of the reinforcing bar material used for the various hole-side reinforcing bars 27 to 30. For example, such a reinforcing bar material may be a reinforcing bar material such as a deformed steel bar specified in JIS G 3112 such as SD295A and SD345, or a reinforcing bar material such as a high-strength deformed steel bar of about 785 N / mm class ² . .. Further, the reinforcing bar material used for the various horizontal reinforcing bars 23 and 24 is preferably one having a strength equal to or higher than the strength of the reinforcing bar material used for the various hole-side reinforcing bars 27 to 30. In particular, such a reinforcing bar material is preferably SD345 deformed steel bars.

However, the upper and lower horizontal reinforcing bars are not limited to the above, and may be as follows. The number of various horizontal reinforcing bars may be set to two or more depending on the structure of the beam, the strength of the beam, and the like. In particular, when the number of upper or lower horizontal reinforcements is set to 3 or more, the beam opening reinforcement structure is placed between them in the width direction in addition to the above-mentioned two upper or lower horizontal reinforcements. It may have one or more upper or lower horizontal reinforcing bars located.

[Details of opening reinforcement]
Details of the upper and lower opening reinforcing bars 25 and 26 will be described. In the present embodiment, as shown in FIG. 1, the beam opening reinforcing structure 2 has four upper opening reinforcing bars 25 and four lower opening reinforcing bars 26. It is preferable that the number of the upper opening reinforcing bars 25 is the same as the number of the lower opening reinforcing bars 26.

The four upper opening reinforcing bars 25 are arranged at intervals in the longitudinal direction from each other, and the four lower opening reinforcing bars 26 are also arranged at intervals in the longitudinal direction from each other. In particular, it is preferable that the four upper opening reinforcing bars 25 are arranged at substantially equal intervals at the opening upper pitch length S1 and the four lower opening reinforcing bars 26 are arranged at the opening lower pitch length S2. It is preferable that they are arranged at substantially equal intervals. For example, each of the upper and lower pitch lengths S1 and S2 of the opening is preferably 7.5 times or less the diameter of the reinforcing bar of the main bar 21.

Further, each upper opening reinforcing bar 25 surrounds the main bar 21 of the first and second main bar rows R1 and R2 and the central portion 23a of the upper horizontal reinforcing bar 23, and each lower opening reinforcing bar 26 comprises. It surrounds the main bar 21 of the third and fourth main bar rows R3 and R4 and the central portion 24a of the lower horizontal reinforcing bar 24.

As shown in FIG. 2, each upper opening reinforcing bar 25 has an upper and lower outer end portion (that is, an upper end portion) 25a located corresponding to the main bar 21 of the first main bar row R1 in the vertical direction, and an upper horizontal reinforcing bar. It has a vertical center side end portion (that is, a lower end portion) 25b located corresponding to the central portion 23a of the 23 in the vertical direction. Each upper opening reinforcing bar 25 also has a front side end portion 25c located corresponding to the first main bar 21 of the second main bar row R2 in the width direction and a fourth main bar 21 of the second main bar row R2 in the width direction. It has a back side end portion 25d and is located correspondingly to each other. It is preferable that the outer peripheral edge of the upper opening reinforcing bar 25 is formed in a substantially quadrangular shape.

Each lower opening reinforcing bar 26 has an upper and lower outer end portion (that is, a lower end portion) 26a located corresponding to the main bar 21 of the fourth main bar row R4 in the vertical direction, and a central portion 24a of the lower horizontal reinforcing bar 24. Has an upper and lower center side end portion (that is, an upper end portion) 26b located correspondingly in the vertical direction. Each lower opening reinforcing bar 26 also has a front end 26c located corresponding to the first main bar 21 of the third main bar row R3 in the width direction and a fourth main bar 21 of the third main bar row R3 in the width direction. It has a back side end portion 26d correspondingly located at. It is preferable that the outer peripheral edge of the lower opening reinforcing bar 26 is formed in a substantially square shape.

With reference to FIGS. 2 and 5, the shape of the upper opening reinforcing bar 25 will be described below. The upper and lower opening reinforcing bars 25 and 26 are formed substantially vertically symmetrically. In the following, a preferable shape of the upper opening reinforcing bar 25 will be described, and the preferred shape of the lower opening reinforcing bar 26 will be described. The explanation is omitted.

The upper opening reinforcing bar 25 is formed into a main body member 41 formed in a substantially U shape so as to open toward the center in the vertical direction of the beam 1, and a U shape corresponding to the opening of the main body member 41. It also has a cap member 42. As shown in FIG. 5, the main body member 41 includes the upper and lower outer end portions 41a located on the outer side in the vertical direction of the beam 1, and the front side and back side end portions 41b located on the front side and the back side of the beam 1, respectively. It has 41c and.

The main body member 41 also has front side and back side hook portions 41d, 41e formed so as to be curved from the tips of the front side and back side end portions 41b, 41c to the center side in the width direction of the main body member 41, respectively. .. The front side and back side hook portions 41d and 41e are adapted to engage with the central portion 23a of the front side and back side upper horizontal reinforcing bars 23, respectively. In particular, the bending angles of the front side and back side hook portions 41d and 41e are preferably 135 ° or 180 ° with respect to the longitudinal direction.

The cap member 42 has a cap portion 42a extending in the width direction corresponding to the opening of the main body member 41, and front side and back surfaces protruding outward in the vertical direction from the front side end and the back side end in the longitudinal direction of the cap portion 42a, respectively. It has side arms 42b and 42c. In particular, the lengths of the front side and back side arm portions 42b and 42c are preferably about 2.5 times or more the diameter of the reinforcing bar of the main body member 41.

The upper and lower outer end portions 41a of the main body member 41 correspond to the upper and lower outer end portions 25a of the upper opening reinforcing bar 25. The front and back hook portions 41d and 41e of the main body member 41 and the cap portion 42a of the cap member 42 correspond to the upper and lower center side end portions 25b of the upper opening reinforcing bar 25. The front side end portion 41b of the main body member 41 and the front side arm portion 42b of the cap member 42 correspond to the front side end portion 25c of the upper opening reinforcing bar 25. The back side end portion 41c of the main body member 41 and the back side arm portion 42c of the cap member 42 correspond to the back side end portion 25d of the upper opening reinforcing bar 25.

Further, in the modified example of the present embodiment, the upper and lower opening reinforcing bars can be formed into the following shapes instead of the shape having the main body member 41 and the cap member 42 as described above. In the modified example of the present embodiment, the upper and lower opening reinforcing bars are formed substantially vertically symmetrically. In the following, the preferable shape of the upper opening reinforcing bar will be described, and the lower opening reinforcing bar will be described. The description of the preferable shape of the above is omitted.

As shown in FIGS. 6 and 7, the upper opening reinforcing bar 25'is formed on the front side member 51 formed in a substantially U shape so as to open toward the back side of the beam 1 and on the front side of the beam 1. It has a back surface side member 52 formed in a substantially U shape so as to open toward it. The front side member 51 includes a front side end portion 51a located on the front side of the beam 1, an upper and lower outer end portion 51b located on the outer side in the vertical direction of the beam 1, and upper and lower portions located on the central side in the vertical direction of the beam 1. It has a central end portion 51c. The back side member 52 includes a back side end portion 52a located on the back side of the beam 1, an upper and lower outer end portion 52b located on the outer side in the vertical direction of the beam 1, and upper and lower portions located on the central side in the vertical direction of the beam 1. It has a central end portion 52c.

It is preferable that the upper and lower outer end portions 51b of the front side member 51 are longer than the upper and lower center side end portions 51c of the front side member 51. It is preferable that the upper and lower outer end portions 52b of the back surface side member 52 are longer than the upper and lower center side end portions 52c of the back surface side member 52. It is preferable that the lengths of the upper and lower outer end portions 51b and 52b of the front side and back side members 51 and 52 are substantially the same.

The upper and lower outer end portions 51b and 52b of the front side and back side members 51 and 52 correspond to the upper and lower outer end portions 25a'of the upper opening reinforcing bar 25'. The upper and lower center side ends 51c and 52c of the front side and back side members 51 and 52 correspond to the upper and lower center side ends 25b'of the upper opening reinforcing bar 25'. The front side end portion 51a of the front side member 51 corresponds to the front side end portion 25c'of the upper opening reinforcing bar 25'. The back side end portion 52a of the back side member 52 corresponds to the back side end portion 25d'of the upper opening reinforcing bar 25'.

It is preferable that the reinforcing bar materials used for such various opening reinforcing bars 25, 25', 26 are the same. Further, the reinforcing bar material used for the various opening reinforcing bars 25, 25', 26 may be of the same steel type or higher as the reinforcing bar material used for the various hole-side reinforcing bars 27 to 30. For example, such a reinforcing bar material may be a reinforcing bar material such as a deformed steel bar specified in JIS G 3112 such as SD295A and SD345, or a reinforcing bar material such as a high-strength deformed steel bar of about 785 N / mm class ² . .. Further, the reinforcing bar material used for the various opening reinforcing bars 25, 25', 26 is preferably one having a strength equal to or higher than the strength of the reinforcing bar material used for the various hole-side reinforcing bars 27 to 30. In particular, such a reinforcing bar material is preferably SD345 deformed steel bars.

However, the upper and lower opening reinforcing bars are not limited to the above, and may be as follows. The number of various opening reinforcing bars may be set to two or more depending on the structure of the beam, the strength of the beam, and the like. Further, the upper and lower opening reinforcing bars may be formed asymmetrically in the vertical direction.

[Details of various hole reinforcements]
Details of the left outer and left inner hole reinforcements 27 and 28 and the right outer and right inner hole reinforcements 29 and 30 will be described. In the present embodiment, as shown in FIG. 1, the beam opening reinforcing structure 2 has three left lateral aperture reinforcing bars 27 and three right lateral aperture reinforcing bars 29. The beam opening reinforcement structure 2 has three left inner hole reinforcements 28 and three right inner hole reinforcements 30. It is preferable that the number of the left lateral aperture reinforcing bars 27, the number of the left medial aperture reinforcing bars 28, the number of the right lateral aperture reinforcing bars 29, and the number of the right medial aperture reinforcing bars 30 are the same. The number of various hole-side reinforcing bars may be set to 3 or more depending on the structure of the beam, the strength of the beam, and the like.

The three left lateral aperture reinforcements 27 are spaced apart from each other in the width direction, and the three left inner aperture reinforcements 28 are spaced apart from each other in the width direction. Each left outer aperture reinforcing bar 27 and each left inner aperture reinforcing bar 28 are located between the opening 1a in the width direction and one end in the longitudinal direction of each opening reinforcing member 22. The three right lateral aperture reinforcements 29 are arranged at intervals in the width direction from each other, and the three right inner hole reinforcement bars 30 are arranged at intervals in the width direction from each other. Each right outer aperture reinforcing bar 29 and each right inner aperture reinforcing bar 30 are located between the opening 1a in the width direction and the other end in the longitudinal direction of each opening reinforcing member 22.

The three left lateral aperture reinforcements 27 are respectively located corresponding to the three left inner aperture reinforcements 28 in the width direction. The three right lateral aperture reinforcements 29 are respectively located corresponding to the three right inner aperture reinforcements 30 in the width direction. In particular, it is preferable that the three left outer hole reinforcing bars 27 are arranged at substantially equal intervals at the left hole pitch length T1, and the three right outer hole reinforcing bars 29 have the right hole pitch length. It is preferable that they are arranged at approximately equal intervals at T2. Further, it is preferable that the pitch lengths T1 and T2 near the left and right holes are substantially equal. It is preferable that the left-side and right-side hole pitch lengths T1 and T2 are smaller than the opening upper and lower pitch lengths S1 and S2, respectively.

Various outer aperture reinforcing bars 27 and 29 surround all main bars 21. The various inner hole reinforcing bars 28 and 30 surround the second and third main bars 21 of the first to fourth main bar rows R1 to R4.

With reference to FIG. 3, the shapes of the left outer and left inner hole reinforcements 27 and 28 will be described below. The left outer and left inner hole reinforcements 27 and 28 are formed substantially in the same manner as the right outer and right inner hole reinforcements 29 and 30, respectively. In the following, the left outer and left inner reinforcements are formed. The preferable shapes of the hole-side reinforcing bars 27 and 28 will be described, and the description of the preferable shapes of the right outer and right inner hole-side reinforcing bars 29 and 30 will be omitted.

Each left lateral aperture reinforcing bar 27 has an upper end portion 27a located vertically corresponding to all the main bars 21 of the first main bar row R1 and all the main bars 21 of the fourth main bar row R4 in the vertical direction. It has a correspondingly located lower end portion 27b. Each left lateral aperture reinforcing bar 27 also has a front side end 27c located corresponding to the first main bar 21 of the first to fourth main bar rows R1 to R4 in the width direction, and the first to fourth main bar rows. It has a back side end portion 27d located corresponding to the fourth main bar 21 of R1 to R4 in the width direction. It is preferable that each such left outer hole edge reinforcing bar 27 extends in a substantially quadrangular shape.

Each left inner hole reinforcing bar 28 has an upper end portion 28a located corresponding to the second and third main bars 21 of the first main bar row R1 in the vertical direction, and the second and third main bars of the fourth main bar row R4. It has a lower end portion 28b located corresponding to 21 in the vertical direction. Each left medial hole reinforcement 28 also has a front end 28c located corresponding to the second main bars 21 of the first to fourth main bars R1 to R4 in the width direction, and the first to fourth main bars 28. It has a back side end portion 28d located corresponding to the third main bar 21 of R1 to R4 in the width direction. It is preferable that each such left inner hole edge reinforcing bar 28 extends in a substantially square shape.

It is preferable that the reinforcing bar materials used for the various hole-side reinforcing bars 27 to 30 are the same. For example, the reinforcing bar materials used for the various hole-side reinforcing bars 27 to 30 are reinforcing bars such as deformed steel bars specified in JIS G 3112 such as SD295A and SD345, or high-strength deformed steel bars of about 785 N / mm class ² . It is preferable to use a reinforcing bar material such as. In particular, such a reinforcing bar material is preferably SD345 deformed steel bars.

[Details of various shear reinforcements]
The details of the left outer and left inner shear reinforcing bars 31 and 32 and the right outer and right inner shear reinforcing bars 33 and 34 will be described. In the present embodiment, as shown in FIG. 1, the beam opening reinforcing structure 2 has a plurality of left outer shear reinforcing bars 31 and a plurality of right outer shear reinforcing bars 33. The beam opening reinforcing structure 2 has a plurality of left inner shear reinforcing bars 32 and a plurality of right inner shear reinforcing bars 34. It is preferable that the number of the left outer shear reinforcing bars 31, the number of the left inner shear reinforcing bars 32, the number of the right outer shear reinforcing bars 33, and the number of the right inner shear reinforcing bars 34 are the same.

The plurality of left outer shear reinforcing bars 31 are arranged at intervals in the width direction from each other, and the plurality of left inner shear reinforcing bars 32 are arranged at intervals in the width direction from each other. The plurality of right outer shear reinforcing bars 33 are arranged at intervals in the width direction from each other, and the plurality of right inner shear reinforcing bars 34 are arranged at intervals in the width direction from each other. The plurality of left outer shear reinforcing bars 31 are respectively located corresponding to the plurality of left inner shear reinforcing bars 32 in the width direction. The plurality of right outer shear reinforcing bars 33 are respectively located corresponding to the plurality of right inner shear reinforcing bars 34 in the width direction. In particular, the plurality of left outer shear reinforcing bars 31 may be arranged at substantially equal intervals with the left rib pitch length U1, and the plurality of right outer shear reinforcing bars 33 may be substantially spaced with the right rib pitch length U2. It should be arranged at equal intervals. Further, the left side and right side rib pitch lengths U1 and U2 are larger than the left side and right side hole pitch lengths T1 and T2, respectively. It is preferable that the left and right rib pitch lengths U1 and U2 are substantially equal.

Various outer shear reinforcing bars 31, 33 surround all the main bars 21. Various inner shear reinforcing bars 32 and 34 surround the second and third main bars 21 of the first to fourth main bar rows R1 to R4.

With reference to FIG. 4, the shapes of the left outer and left inner shear reinforcing bars 31 and 32 will be described below. The left outer and left inner shear reinforcing bars 31 and 32 are formed substantially in the same manner as the right outer and right inner shear reinforcing bars 33 and 34, respectively. The preferable shapes of the reinforcing bars 31 and 32 will be described, and the description of the preferable shapes of the right outer and right inner shear reinforcing bars 33 and 34 will be omitted.

Each left outer shear reinforcing bar 31 corresponds vertically to the upper end portion 31a located corresponding to all the main bars 21 of the first main bar row R1 and to all the main bars 21 of the fourth main bar row R4 in the vertical direction. It has a lower end portion 31b and is located there. Each left lateral shear reinforcing bar 31 also has a front side end 31c located corresponding to the first main bar 21 of the first to fourth main bar rows R1 to R4 in the width direction, and the first to fourth main bar rows R1. It has a back side end portion 31d located corresponding to the fourth main bar 21 of R4 in the width direction. It is preferable that each such left outer shear reinforcing bar 31 extends in a substantially square shape.

Each left inner shear reinforcing bar 32 has an upper end portion 32a located corresponding to the second and third main bars 21 of the first main bar row R1 in the vertical direction, and the second and third main bars 21 of the fourth main bar row R4. Has a lower end portion 32b located corresponding to the vertical direction. Each left inner shear reinforcing bar 32 also has a front side end portion 32c located corresponding to the second main bar 21 of the first to fourth main bar rows R1 to R4 in the width direction, and the first to fourth main bar rows R1. It has a back side end portion 32d located corresponding to the third main bar 21 of R4 in the width direction. It is preferable that each such left inner shear reinforcing bar 32 extends in a substantially square shape.

It is preferable that the reinforcing bar materials used for the various shear reinforcing bars 31 to 34 are the same. Further, the reinforcing bar diameter of the reinforcing bar material used for the various shear reinforcing bars 31 to 34 may be equal to or smaller than the reinforcing bar diameter of the reinforcing bar material used for the various hole-side reinforcing bars 27 to 30. For example, the reinforcing bar materials used for various shear reinforcing bars 31 to 34 are reinforcing bars such as deformed steel bars specified in JIS G 3112 such as SD295A and SD345, or high-strength deformed steel bars of about 785 N / mm class ² . It is good to use the reinforcing bar material of. Further, the reinforcing bar material used for the various shear reinforcing bars 31 to 34 may have a strength equal to or lower than the strength of the reinforcing bar material used for the various hole-side reinforcing bars 27 to 30. In particular, such a reinforcing bar material is preferably SD345 deformed steel bars.

[About the unity of each component]
The unity of each component will be described. It is preferable that a binding line (not shown) is used for binding. The first opening reinforcing member 22 abuts and binds to the upper and lower horizontal reinforcing bars 23 and 24 on the front side and the front end portions 27c of the left and right outer aperture reinforcing bars 27 and 29. The third opening reinforcing member 22 abuts and binds to the upper and lower horizontal reinforcing bars 23 and 24 on the back surface side and the back surface side end portions 27d of the left and right outer aperture reinforcing bars 27 and 29.

The upper horizontal reinforcing bars 23 on the front side are the lower end portions 25b, 25b'of the upper opening reinforcing bars 25, 25', particularly the front hook portion 41d of the main body member 41, and the left outer aperture and shear reinforcing bars 27, 31. 27c, 31c and the front right end of the lateral aperture and the front end of the shear reinforcing bars 29, 33 are abutted and bound. The upper horizontal reinforcing bar 23 on the back side includes the lower end portions 25b, 25b'of the upper opening reinforcing bars 25, 25', particularly the back side hook portion 41e of the main body member 41, and the left outer aperture and shear reinforcing bars 27, 31. 27d, 31d on the back side of the above, and the back side end of the right outer hole and the shear reinforcing bars 29, 33 are abutted and bound.

The lower horizontal reinforcing bar 24 on the front side is the upper end portion 26b of the lower opening reinforcing bar 26, particularly the front side hook portion of the main body member, the left outer aperture, and the front side end portion 27c of the shear reinforcing bars 27 and 31. , 31c and the right lateral aperture and the front end of the shear reinforcements 29, 33 are abutted and bound. The lower horizontal reinforcing bar 24 on the back side is the lower end portion 26a of the lower opening reinforcing bar 26, particularly the back side hook portion of the main body member, the left outer aperture, and the back side end portion 27d of the shear reinforcing bars 27 and 31. , 31d abuts and binds to the right lateral aperture and the back end of the shear reinforcements 29 and 33.

The upper opening reinforcing bars 25, 25'are in contact with and bound to at least a part of the main bars 21 of the first main bar row R1 and the first and fourth main bars 21 of the second main bar row R2. The lower opening reinforcing bar 26 abuts and binds to the first and fourth main bars 21 of the third main bar row R3 and at least a part of the main bars 21 of the fourth main bar row R4.

The various lateral aperture reinforcing bars 27 and 29 include at least a part of the main bars 21 of the first main bar row R1, the first and fourth main bars 21 of the second and third main bar rows R2 and R3, and the fourth main bar row R4. It abuts and binds to at least a part of the main bar 21 of the above. The various inner hole reinforcing bars 28 and 30 abut and bind to the second and third main bars 21 of the first to fourth main bar rows R1.

The various outer shear reinforcing bars 31 and 33 include at least a part of the main bars 21 of the first main bar row R1, the first and fourth main bars 21 of the second and third main bar rows R2 and R3, and the fourth main bar row R4. It abuts and binds to at least a part of the main bar 21. The various inner shear reinforcing bars 32 and 34 abut and bind to the second and third main bars 21 of the first to fourth main bar rows R1.

[Design conditions for beam opening reinforcement structure]
The design conditions of the beam opening reinforcing structure 2 will be described. The height H of the beam 1 is set to be about 2.5 times or more and less than about 3 times the diameter D of the opening 1a. The relationship between the diameter D of the openings 1a, the reinforcing bar diameters d of the various horizontal reinforcing bars 23 and 24, the predetermined coefficient α, and the length L of the various horizontal reinforcing bars 23 and 24 is described in the following (Equation 2). Is defined as.

L = D + 2 × α × d ・ ・ ・ (Equation 2)

In this case, D is set to about 500 mm to about 750 mm as described above, and d is equal to or larger than the diameters of the left outer and left inner hole reinforcing bars 27 and 28 and the right outer and right inner hole reinforcing bars 29 and 30. The diameter of each main bar 21 is equal to or smaller than the diameter of the reinforcing bar, and α is set to about 14.4 to about 21. In this case, it is preferable that the diameter of the reinforcing bar of each main bar 21 is larger than the diameter of the reinforcing bars 27 and 28 at the left outer and left inner holes and the reinforcing bars 29 and 30 at the right outer and right inner holes.

For such conditions, the height H of the beam 1 is set to be about 2.5 times or more the diameter D of the opening 1a from the viewpoint of sufficiently obtaining the strength of the beam opening reinforcing structure 2. From the viewpoint of making the height H of the beam 1 lower than that of the conventional one, the height H of the beam 1 determined based on the diameter D of the opening 1a is set to be less than about 3 times the diameter D of the opening 1a. .. From the viewpoint of allowing people, equipment, etc. to pass through, the diameter D of the opening 1a is set to about 500 mm or more. From the viewpoint of lowering the height H of the beam 1 determined based on the diameter D of the opening 1a, the diameter D of the opening 1a is set to about 750 mm or less.

From the viewpoint of sufficiently obtaining the yield strength of the horizontal reinforcing bars 23 and 24 and the yield strength of the beam opening reinforcing structure 2 based on the yield strength, the reinforcing bar diameters d of the horizontal reinforcing bars 23 and 24 are set near the left outer and left inner holes. The diameters of the reinforcing bars 27 and 28 and the reinforcing bars 29 and 30 at the right outer and right inner holes are equal to or larger than those of the reinforcing bars 27 and 28. From the viewpoint of sufficiently obtaining the toughness of the horizontal reinforcing bars 23 and 24 and the toughness of the beam opening reinforcing structure 2 based on the toughness, the reinforcing bar diameter d of the horizontal reinforcing bars 23 and 24 is set to be equal to or smaller than the reinforcing bar diameter of the main reinforcing bars 21. .. From the viewpoint that each end 23b, 23c, 24b, 24c of each horizontal reinforcing bar 23, 24 sufficiently fulfills the function as fixing, the constant α is set to about 14.4 or more. In particular, the constant α is set to about 21 or less from the viewpoint of making the ends 23b, 23c, 24b, 24c of each of the horizontal reinforcing bars 23, 24 as fixing shorter than the conventional ones.

As described above, according to the beam opening reinforcement structure 2 according to the present embodiment, in the beam 1 having the opening 1a through which people, equipment and the like can pass, the beam 1 is installed in the peripheral portion 1b of the beam opening as described above. The beam 1 is efficiently reinforced by the opening reinforcing member 22, various horizontal reinforcing bars 23, 24, various opening reinforcing bars 25, 25', 26, and various edge reinforcing bars 27 to 30. Therefore, even when the height H of the beam 1 is kept 2.5 times or more and less than 3 times the diameter D of the opening 1a and the height H of the beam 1 is made lower than before, the beam The strength of 1 can be sufficiently secured. In particular, in the beam opening reinforcement structure 2 based on the above design conditions, when the lengths of the ends 23b, 23c, 24b, 24c of the various horizontal reinforcing bars 23, 24, that is, the fixing length is shorter than before. Even so, the strength of the beam 1 can be efficiently secured by the reinforcement as described above. Therefore, it is possible to prevent the beam 1 from becoming large while efficiently ensuring the strength of the beam 1, and the length of fixing of the various horizontal reinforcing bars 23 and 24 provided in the peripheral portion 1b of the opening of the beam 1 is increased. Can be shortened.

Although the present embodiment has been described so far, the present invention is not limited to the above-described embodiment, and the present invention can be modified and modified based on the technical idea thereof.

1 Beam 1a opening, 1b Peripheral opening 2 Beam opening reinforcement structure 21 Main reinforcement (1st to 4th main reinforcement)
22 Fenestra reinforcement member (1st to 3rd perforation reinforcement member)
23 Upper horizontal reinforcement 23a Central, 23b One end, 23c Other end 24 Lower horizontal reinforcement 24a Central, 24b One end, 24c Other end 25, 25'Upper opening reinforcement 26 Lower opening reinforcement Reinforcement 27 Left lateral hole reinforcement 28 Left medial hole reinforcement 29 Right lateral hole reinforcement 30 Right medial hole reinforcement 31 Left lateral shear reinforcement 32 Left medial shear reinforcement 33 Right lateral shear reinforcement 34 Right medial Shear reinforcement L Horizontal reinforcement length, H beam height, D Opening diameter, d Horizontal reinforcement diameter

Claims (2)

A reinforced concrete beam arranged along the horizontal direction of the building is formed with an opening having a circular or polygonal cross section while penetrating in the width direction thereof to reinforce the peripheral portion of the opening of the beam. It is a beam opening reinforcement structure configured as
A plurality of main bars extending in the longitudinal direction of the beam,
An opening reinforcing member arranged so as to surround the opening,
Upper and lower horizontal reinforcing bars extending linearly in the longitudinal direction and arranged above and below the opening, respectively.
An upper opening reinforcing bar that surrounds the upper horizontal reinforcing bar and is arranged above the opening.
A lower opening reinforcing bar that surrounds the lower horizontal reinforcing bar and is arranged below the opening.
The left outer and right outer hole reinforcement bars that surround the plurality of main bars and are arranged on the left and right sides in the longitudinal direction with respect to the opening, respectively.
It is provided with left-outer and right-outer shear reinforcements that surround the plurality of main bars and are arranged on the left-outer and right-outer edge reinforcements on the sides away from the opening in the longitudinal direction, respectively. ,
The height of the beam is 2.5 times or more and less than 3 times the diameter of the opening.
Various horizontal reinforcing bars have a central portion arranged in the longitudinal direction in accordance with the opening, and both end portions arranged on both sides in the longitudinal direction with respect to the central portion.
Both ends of various horizontal reinforcing bars are fixed,
The length of the various horizontal reinforcing bars is L, the diameter of the cross section of the opening is D, the diameter of the reinforcing bars of the various horizontal reinforcing bars is d, the predetermined coefficient is α, and the length of the various horizontal reinforcing bars is ,
L = D + 2 × α × d ・ ・ ・ (Equation 1)
Determined based on
D is 500 mm to 750 mm,
d is not less than or equal to the diameter of the reinforcing bar of various hole-side reinforcing bars and less than or equal to the diameter of the reinforcing bar of the main bar.
Beam opening reinforcement structure with α of 14.4 to 21. Two or more of the opening reinforcing members are provided so as to be spaced apart in the width direction of the beam.
Two or more horizontal reinforcing bars are provided so as to be spaced apart from each other in the width direction.
Two or more opening reinforcing bars are provided so as to be spaced apart from each other in the longitudinal direction.
Three or more various hole-side reinforcing bars are provided so as to have a predetermined pitch interval in the longitudinal direction.
A plurality of various shear reinforcing bars are provided so as to have a predetermined pitch interval in the longitudinal direction.
The beam opening reinforcing structure according to claim 1, wherein the pitch spacing of the various hole-side reinforcing bars is smaller than the pitch spacing of the various shear reinforcing bars.

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