Beam member, and joining structure between beam member and vertical member

Abstract

To provide a precast concrete beam member that can increase the shear strength of the member and its joint part with other members without increasing the section size.SOLUTION: A precast concrete beam member 20 is provided with a beam body 21 formed of steel fiber reinforced concrete, beam main reinforcement 22 and shear reinforcement 23 arranged inside the beam body 21, and convex parts 24 provided on both end faces of the beam body 21. The convex part 24 is formed of steel fiber-reinforced concrete. By joining the beam member 20 and a column member 10 in a shear key composed of the convex part 24 of the beam member 20 and a concave part 11 of the column member 10, the shear strength of the joint part between the beam member 20 and the column member 10 and the deformation performance of the beam member 20 can be increased without increasing the cross-sectional size of the beam member, improving the concrete strength of the beam member and increasing the amount of reinforcement for shear reinforcement.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a beam member and a joining structure between this beam member and a vertical member.

Background Art

[0002] Conventionally, there has been a structure including a pair of concrete members and a precast concrete beam member installed between these pair of concrete members (see Patent Documents 1 to 3). Patent Document 1 shows a beam of a reinforced concrete structure with X-shaped reinforcement in which main beam reinforcements are arranged in an X shape within the beam span, and the upper main reinforcement at one beam end and the lower main reinforcement at the other beam end are arranged continuously. Adhesion prevention means is provided to prevent the adhesion between the main beam reinforcements arranged in an X shape and the concrete of the beam over the entire length of the beam span.

[0003] Patent Document 2 shows an RC beam damper that connects seismic walls of RC or SRC construction. In this RC beam damper, fiber-reinforced concrete is used as the concrete, low yield point steel bars are used as the main reinforcements, and prestress is introduced by PC steel bars. Further, the main reinforcements are arranged in an X shape between both ends of the beam (X-shaped reinforcement). Patent Document 3 shows a joining structure between a beam body of precast concrete construction and a core wall. The beam body is made of a fiber-reinforced cement-based material, and main beam reinforcements and stirrups are embedded.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a beam member made of precast concrete and a joint structure between the beam member and a vertical member, which can increase the shear strength of the joint portion with other members without increasing the cross-sectional size.

Means for Solving the Problems

[0006] The inventors of the present invention have formed a beam member made of precast concrete with steel fiber reinforced concrete, and formed convex portions at both ends of the beam member, so as to increase the cross-sectional size of the beam member, increase the concrete strength of the beam member, or arrange shear reinforcement bars at high density. Focusing on the fact that the bearing capacity and deformation performance of the beam member can be improved without doing so, the present invention has been achieved. The beam member of the first invention is a beam member made of precast concrete (for example, the beam member 20 described later), and includes a beam main body (for example, the beam main body 21 described later) formed of steel fiber reinforced concrete, and a beam main reinforcement (for example, the beam main reinforcement 22 described later) and shear reinforcement bars (for example, the shear reinforcement bars 23 described later) arranged inside the beam main body, and convex portions (for example, the convex portions 24 described later) provided on both end faces of the beam main body, and the convex portions are characterized in that they are formed of steel fiber reinforced concrete.

[0007] According to this invention, convex portions made of steel fiber reinforced concrete are provided on both end faces of the beam member. Steel fiber reinforced concrete is a material in which steel fibers are mixed into concrete, and has the effect of preventing cracks from opening and suppressing damage to the structure. Therefore, at the time of an earthquake, since the steel fiber reinforced concrete bears a certain amount of tensile force, the shear bearing capacity of the beam member and the convex portion can be increased. Therefore, by joining with other members using this shear key of the convex portion, the shear strength of the joint portion between the beam member and other members can be increased without increasing the cross-sectional size of the beam member, improving the concrete strength of the beam member, or increasing the amount of steel bars of the shear reinforcement bars. The steel fibers are processed with hooks at both ends, and preferably have a length of about 0.1 mm to 0.6 mm. Also, the mixing amount of the steel fibers is preferably about 0.5% to 1.5% with respect to the concrete volume.

[0008] The beam member of the second invention, the beam main reinforcement includes a first beam main reinforcement (for example, the first beam main reinforcement 30 described later) and a second beam main reinforcement (for example, the second beam main reinforcement 40 described later), and the first beam main reinforcement is from the upper end side of one beam end portion (for example, the beam end portion P described later) of the beam main body to the lower end side of the other beam end portion (for example, the beam end portion Q described later) of the beam main body. A first inclined portion (for example, the first inclined portion 31 described later) extending linearly, and a first parallel portion (for example, the first parallel portion 32 described later) extending linearly outward from both ends of the first inclined portion substantially parallel to the central axis of the beam main body, and the second beam main reinforcement is from the lower end side of one beam end portion of the beam main body to the upper end side of the other beam end portion of the beam main body. A second inclined portion (for example, the second inclined portion 41 described later) extending linearly, and a second parallel portion (for example, the second parallel portion 42 described later) extending linearly outward from both ends of the second inclined portion substantially parallel to the central axis of the beam main body.

[0009] According to this invention, the first beam main reinforcement is configured to include a first inclined portion and a first parallel portion, and the second beam main reinforcement is configured to include a second inclined portion and a second parallel portion. That is, in a side view, the first inclined portion of the first beam main reinforcement and the second inclined portion of the second beam main reinforcement are arranged in an X shape. Therefore, with respect to the reverse symmetric bending moment generated during an earthquake, the beam main reinforcement is in a tensile state or a compressive state to bear the shear force, and adhesive splitting failure is less likely to occur, so the deformation ability (toughness performance) of the beam member can be enhanced.

[0010] Also, inside the beam main body, when viewed from the side, the first inclined portion of the first beam main reinforcement and the second inclined portion of the second beam main reinforcement form an X shape, but outside the beam main body, the first parallel portion of the first beam main reinforcement and the second parallel portion of the second beam main reinforcement extend substantially parallel to the central axis of the beam main body. Therefore, the parallel portions extending outside the beam main body can be relatively easily joined to other members. In addition, since the bent portions of the first main beam reinforcement bars and the second main beam reinforcement bars are the ends within the beam body, the workability of the reinforcement work in the on-site work when installing the precast concrete member can be improved. In addition, since the steel fiber reinforced concrete bears a certain amount of tensile force, it becomes possible to reduce the shear reinforcement bars and avoid over-dense reinforcement. In addition, in order to enhance the deformation capacity (toughness performance) and member bearing capacity over the entire length of the beam member, it is preferable that the bent portion of the main beam reinforcement bar is outside the beam member. However, since steel fiber concrete is used for the beam member, the fiber reinforced concrete bears a certain amount of tensile force, so even if the bent portion of the main beam reinforcement bar is the beam end, the deformation capacity and member bearing capacity of the beam member can be ensured.

[0011] The joint structure between the beam member of the third invention and the vertical member (for example, the column-beam frameworks 1, 1A, 1B, 1C described later) includes a pair of vertical members (for example, the column member 10 described later) and a precast concrete beam member (for example, the beam member 20 described later) installed between the pair of vertical members. The beam member includes a beam body (for example, the beam bodies 21, 21A described later) formed of steel fiber reinforced concrete, main beam reinforcement bars (for example, the main beam reinforcement bars 22 described later) and shear reinforcement bars (for example, the shear reinforcement bars 23 described later) arranged inside the beam body, and convex portions (for example, the convex portions 24 described later) or concave portions (for example, the concave portions 25 described later) formed on both end faces of the beam body. On the side surface of the vertical member, a concave portion (for example, the concave portion 11 described later) into which the convex portion of the beam member fits or a convex portion (for example, the convex portion 12 described later) that fits into the concave portion of the beam member is formed.

[0012] According to this invention, since the beam member and the vertical member are joined by a shear key in which the convex portion and the concave portion are fitted, the shear strength of the joint portion between the column member and the beam member can be greatly ensured without increasing the cross-sectional size of the beam member, improving the concrete strength of the beam member, or increasing the amount of reinforcing bars of the shear reinforcement bars.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a precast concrete beam member and a joint structure between the beam member and a vertical member, which can increase the shear strength of the joint portion between the beam member and other members without increasing the cross-sectional size.

Brief Description of the Drawings

[0014]

Figure 1

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Modes for Carrying Out the Invention

[0015] The present invention relates to a beam member made of precast concrete formed of steel fiber reinforced concrete, and a joining structure between this beam member and a vertical member. The first feature of the beam member of the present invention is that the beam main body and the convex portion are formed of steel fiber reinforced concrete. Further, the second feature of the beam member of the present invention is that the reinforcing bars (first diagonal portion, second diagonal portion) arranged in an X shape are bent inside the beam main body (beam end portion), and the reinforcing bars (first parallel portion, second parallel portion) extending outward from the beam main body are arranged parallel to the material axis direction of the beam main body. Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the following embodiments, the same reference numerals are given to the same constituent elements, and the description thereof is omitted or simplified. 〔First Embodiment〕 FIG. 1 is a longitudinal sectional view of a column-beam frame 1 as a joining structure between a beam member and a vertical member according to the first embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing the reinforcement arrangement of the beam member 20. FIG. 3(a) is a view taken along the line A-A of the beam member 20 in FIG. 2, and FIG. 3(b) is a view taken along the line B-B of the beam member 20 in FIG. 2. The column-beam frame 1 includes column members 10 as a pair of vertical members, and a precast concrete beam member 20 installed between the pair of column members 10. The beam member 20 includes a beam main body 21 formed of steel fiber reinforced concrete, beam main reinforcement 22 and shear reinforcement 23 arranged inside the beam main body 21, and convex portions 24 formed on both end faces of the beam main body 21. This convex portion 24 is formed of steel fiber reinforced concrete. The column member 10 on the right side in FIG. 1 is a reinforced concrete structure formed by arranging reinforcement on site, building a formwork, and placing concrete. A concave portion 11 into which the convex portion 24 of the beam main body 21 fits is formed on the side surface of this column member 10, and a shear key is constituted by the convex portion 24 of the beam main body 21 and the concave portion 11 of the column member 10. Since the beam member 20 is a precast concrete structure, the concave portion 11 that fits into the convex portion 24 is formed by placing the concrete of the column member 10 on site with the beam member 20 attached to a predetermined position. In Fig. 1, the column member 10 on the left side includes upper and lower precast reinforced concrete members 60, and a reinforced concrete column-beam joint 61 provided between these precast reinforced concrete members 60. This column-beam joint 61 is formed by arranging steel bars on-site, building a formwork, and placing concrete. On the side surface of this column-beam joint 61, a concave portion 11 into which the convex portion 24 of the beam main body 21 fits is formed, and a shear key is constituted by the convex portion 24 of the beam main body 21 and the concave portion 11 of the column-beam joint 61.

[0016] The beam main reinforcement 22 includes a first beam main reinforcement 30, a second beam main reinforcement 40, and a third beam main reinforcement 50. The beam main reinforcement 22 is composed of five upper-end bars and five lower-end bars. Among these, a total of four bars, two upper and two lower on the outside, serve as the third beam main reinforcement 50, and a total of six bars, three upper and three lower on the inside, serve as the first beam main reinforcement 30 and the second beam main reinforcement 40 (see Fig. 3). The first beam main reinforcement 30 is formed by bending a single steel bar at the beam end portions P and Q inside the beam main body 21. This first beam main reinforcement 30 includes a first diagonal portion 31 that extends linearly from the upper-end side of one beam end portion P of the beam main body 21 to the lower-end side of the other beam end portion Q of the beam main body 21, and first parallel portions 32 that extend linearly outward from both ends of the first diagonal portion 31 substantially parallel to the central axis of the beam main body 21. The second beam main reinforcement 40 is formed by bending a single steel bar at the beam end portions P and Q inside the beam main body 21. This second beam main reinforcement 40 includes a second diagonal portion 41 that extends linearly from the lower-end side of one beam end portion P of the beam main body 21 to the upper-end side of the other beam end portion Q of the beam main body 21, and second parallel portions 42 that extend linearly outward from both ends of the second diagonal portion 41 substantially parallel to the central axis of the beam main body 21. The third beam main reinforcement 50 extends linearly substantially parallel to the central axis of the beam main body 21, and both ends protrude outward. The shear reinforcement 23 is a U-shaped steel bar, surrounds the beam main reinforcement 22, and is arranged at predetermined intervals in the length direction of the beam main reinforcement 22.

[0017] 〔Loading Test〕 As comparative examples, specimens (No. 1 to No. 3) with the same configuration as the conventional beam members were fabricated, and as examples, specimens (No. 4 to No. 6) with the same configuration as the beam members of the present invention were fabricated, and a loading test was conducted on these specimens. FIG. 4 is a diagram showing the configuration of the specimen. FIG. 5 is a side view and a cross-sectional view showing the reinforcement arrangement of Specimens No. 1 to No. 3. FIG. 6 is a side view and a cross-sectional view showing the reinforcement arrangement of Specimens No. 4 to No. 6. FIG. 7 is a diagram showing the shape of the shear key. FIG. 8 shows the material test results of the concrete used in the specimen and the material properties of the reinforcing bars used in the specimen. The specimen had a beam width b of 400 mm, a beam depth of 350 mm, and a length of 700 mm. Protrusions with a width of 350 mm, a depth of 20 mm, and a root length of 160 mm were provided at both end faces of the specimen. Note that rigid stubs were provided at both ends of the specimen. For Specimens No. 1 to No. 3, assuming general beam reinforcement, all the upper-side main bars and lower-side main bars were arranged substantially parallel. Also, the shear reinforcement was 4-U7.1@60(p w = 0.67%). For Specimens No. 4 to No. 6, X-shaped reinforcement was used, which is less likely to cause adhesive splitting failure and is effective for short-span beams. Three out of the five tension main bars, excluding the two at the corners, were arranged in an X shape and bent immediately before crossing the dangerous cross-section position to achieve the same flexural strength as that of Specimens No. 1 to No. 3. Also, the shear reinforcement was 2-U7.1@60(p w = 0.33%), which was half the amount of reinforcement of Specimens No. 1 to No. 3.

[0018] The steel fibers mixed in the concrete were those with a length of 35 mm and a diameter of 0.55 mm (aspect ratio 65) with hooks at both ends. In Specimens No. 1 and No. 4, no steel fibers were mixed. In Specimens No. 2 and No. 5, 0.5% of steel fibers were mixed based on the concrete volume. In Specimens No. 3 and No. 6, 1.0% of steel fibers were mixed based on the concrete volume.

[0019] Fig. 9 is a schematic diagram showing a loading test apparatus. A 2000 kN jack was attached to the stub of the test specimen, and the jack was used to apply a reverse symmetric bending shear force. Specifically, a total of 11 times of positive and negative alternating repeated loadings were performed, with the member angle R = ±1 / 500 once and ±1 / 100, ±1 / 50, ±1 / 33, ±1 / 25 twice each, and finally the load was increased until R = ±1 / 20.

[0020] Fig. 10 is a diagram showing the loading test results (comparison of the envelope curves of the relationship between the shear force Q and the member angle R). From Fig. 10, it can be seen that the greater the amount of steel fiber, the higher the ultimate strength, and the improvement of the load drop after the ultimate strength. That is, the test specimens No. 4 to No. 6 with X-shaped reinforcement have higher deformation performance compared to the test specimens No. 1 to No. 3 with general beam reinforcement. Among the test specimens No. 4 to No. 6, for the test specimens No. 5 and No. 6 mixed with steel fibers, the load drop after the ultimate strength is the smallest. Therefore, it can be seen that the mixing of steel fibers is effective in preventing concrete damage and improving toughness performance.

[0021] According to this embodiment, there are the following effects. (1) The beam body 21 of the beam member 20 and the convex portions 24 at both end faces of the beam body 21 are formed of steel fiber reinforced concrete. Therefore, during an earthquake, the steel fiber reinforced concrete bears a certain amount of tensile force, so the shear resistance of the beam body 21 and the convex portion 24 increases. Therefore, by joining the beam member 20 and the column member 10 with the shear key composed of this convex portion 24 and the concave portion 11 of the column member 10, the shear strength of the joint portion between the beam member 20 and the column member 10 can be increased without increasing the cross-sectional size of the beam member, improving the concrete strength of the beam member, or increasing the amount of steel bars of the shear reinforcement.

[0022] (2) The first main beam reinforcement 30 is composed of a first inclined portion 31 and a first parallel portion 32, and the second main beam reinforcement 40 is composed of a second inclined portion 41 and a second parallel portion 42. That is, in a side view, the first inclined portion 31 of the first main beam reinforcement 30 and the second inclined portion 41 of the second main beam reinforcement 40 are arranged in an X shape. Therefore, with respect to the reverse symmetric bending moment generated during an earthquake, the main beam reinforcements 30 and 40 are in a tensile state or a compressive state to bear the shear force, so that the deformation capacity (toughness performance) and shear resistance of the beam member 20 can be enhanced. In addition, steel fiber reinforcement can avoid the concentration of cracks in part, and can suppress the damage of the beam member 20. Also, inside the beam body 21, when viewed from the side, the first inclined portion 31 of the first main beam reinforcement 30 and the second inclined portion 41 of the second main beam reinforcement 40 form an X shape, but outside the beam body 21, the first parallel portion 32 of the first main beam reinforcement 30 and the second parallel portion 42 of the second main beam reinforcement 40 extend substantially parallel to the central axis of the beam body 21. Therefore, the parallel portions 32 and 42 extending outside the beam body 21 can be joined to the column member 10 relatively easily. Moreover, since the bending portions of the first main beam reinforcement 30 and the second main beam reinforcement 40 are the end portions P and Q inside the beam body, the constructability of the reinforcement work can be improved. In addition, in order to enhance the deformation capacity (toughness performance) over the entire length of the beam member 20, it is necessary to make the bending portion of the main beam reinforcement outside the beam member. However, since steel fiber concrete is used for the beam member 20, the fiber-reinforced concrete bears a certain degree of tensile force, so even if the bending portions of the main beam reinforcements 30 and 40 are the beam end portions P and Q, the deformation capacity and shear resistance of the beam member 20 can be ensured.

[0023] (3) Since the beam member 20 is made of precast concrete, steel fiber-reinforced concrete in which steel fibers are sufficiently stirred can be placed at the precast concrete factory. Also, at the construction site, the precast concrete beam member 20 can be carried in, placed at a predetermined position of the building, and joined to other members, and the column-beam structure 1 can be constructed in a relatively short working period.

[0024] 〔Second Embodiment〕 FIG. 11 is a longitudinal sectional view of a column-beam structure 1A according to the second embodiment of the present invention. In this embodiment, recesses 25 are formed on both end faces of the beam body 21A, and projections 12 that fit into the recesses 25 are formed on the side surface of the column member 10, which is different from the first embodiment. The recesses 25 of the beam body 21A are formed of steel fiber reinforced concrete. According to this embodiment, there are the same effects as those of the above (1) to (3).

[0025] 〔Third Embodiment〕 FIG. 12 is a longitudinal sectional view of a column-beam structure 1B according to the third embodiment of the present invention. In this embodiment, the difference from the first embodiment is that both end portions of the beam body 21 are fitted into the recesses 13 on the side surface of the column member 10. That is, recesses 13 are formed on the side surface of the column member 10, and the recess 11 is formed on the bottom surface of the recess 13. Both end portions of the beam body 21 are fitted into the recesses 13 on the side surface of the column member 10, and the projection 24 of the beam body 21 is fitted into the recess 11 of the column member 10. According to this embodiment, in addition to the effects of the above (1) to (3), there are the following effects. (4) Since both end faces of the beam body 21 are fitted into the recesses 13 on the side surface of the column member 10, the shear strength of the joint portion between the beam member 20 and the column member 10 can be further increased.

[0026] 〔Fourth Embodiment〕 FIG. 13 is a longitudinal sectional view of a column-beam structure 1C according to the fourth embodiment of the present invention. In this embodiment, the difference from the second embodiment is that both end portions of the beam body 21A are fitted into the recesses 13 on the side surface of the column member 10. That is, recesses 13 are formed on the side surface of the column member 10, and the projection 12 is formed on the bottom surface of the recess 13. Both end portions of the beam body 21 are fitted into the recesses 13 on the side surface of the column member 10, and the recess 25 of the beam body 21 is fitted into the projection 12 of the column member 10. According to this embodiment, there are the same effects as those of the above (1) to (4).

[0027] Note that the present invention is not limited to the above embodiments, and modifications, improvements, etc. within the scope that can achieve the object of the present invention are included in the present invention. For example, in each of the above-described embodiments, the beam member 20 is installed between the column members 10, but it is not limited thereto. The beam member may be installed between walls or between a wall and a column. Also, in each of the above-described embodiments, each shear reinforcement bar 23 is constituted by a single reinforcing bar, but it is not limited thereto. As shown in FIG. 14, the shear reinforcement bar 23D arranged at the beam ends P and Q may be constituted by two reinforcing bars. Since the bent portions of the beam main bars 30 and 40 are located at the beam ends P and Q, a large component of the stress borne by the beam main bars 30 and 40 acts on the shear reinforcement bar 23D arranged at the beam ends P and Q. Therefore, by constituting the shear reinforcement bar 23D arranged at the beam ends P and Q with two reinforcing bars, the earthquake resistance of the beam member 20 can be enhanced. Also, in each of the above-described embodiments, the beam member 20 is formed of steel fiber reinforced concrete, but without being limited to steel fiber reinforced concrete, it may be formed of any one of vinylon PVA fiber reinforced concrete, PP fiber reinforced concrete, basalt fiber reinforced concrete, cellulose nanofiber CNF fiber reinforced concrete, and fiber reinforced cement composite material (FRCC).

Explanation of Reference Numerals

[0028] 1, 1A, 1B, 1C... Column-beam structure (joint structure between beam member and vertical member) 10... Column member (vertical member) 11... Concave portion 12... Convex portion 13... Concave portion 20... Beam member 21, 21A... Beam body 22... Beam main bar 23, 23D... Shear reinforcement bar 24... Convex portion 25... Concave portion 30... First beam main bar 31... First inclined portion 32... First parallel portion 40... Second beam main bar 41... Second inclined portion 42... Second parallel portion 50... Third beam main bar 60... Precast reinforced concrete member 61... Column-beam joint P, Q... Beam ends

Claims

1. A precast concrete beam member comprising: a beam body formed of steel fiber reinforced concrete; main beam reinforcement bars and shear reinforcement bars arranged inside the beam body; convex portions formed of steel fiber reinforced concrete at both end faces of the beam body, wherein the content of the steel fibers constituting the steel fiber reinforced concrete is 0.5% or more and 1.5% or less with respect to the concrete volume; the main beam reinforcement bars include a first main beam reinforcement bar and a second main beam reinforcement bar; the first main beam reinforcement bar includes a first inclined portion linearly extending from the upper end side of one beam end of the beam body to the lower end side of the other beam end of the beam body, and first parallel portions linearly extending outward from both ends of the first inclined portion substantially parallel to the central axis of the beam body; the second main beam reinforcement bar includes a second inclined portion linearly extending from the lower end side of one beam end of the beam body to the upper end side of the other beam end of the beam body, and second parallel portions linearly extending outward from both ends of the second inclined portion substantially parallel to the central axis of the beam body; the bending portions of the first main beam reinforcement bar and the second main beam reinforcement bar are inside the beam end face within the beam body; and one or two bundled shear reinforcement bars are arranged between the bending portion and the beam end face closer to the bending portion. A beam member characterized by this.

2. A pair of vertical members and a precast concrete beam member installed between the pair of vertical members, wherein the beam member includes a beam body formed of steel fiber reinforced concrete; main beam reinforcement bars and shear reinforcement bars arranged inside the beam body; convex portions formed of steel fiber reinforced concrete at both end faces of the beam body, wherein concave portions into which the convex portions of the beam member are fitted are formed on the side surfaces of the vertical members; the content of the steel fibers constituting the steel fiber reinforced concrete is 0.5% or more and 1.5% or less with respect to the concrete volume; the main beam reinforcement bars of the beam body include a first main beam reinforcement bar and a second main beam reinforcement bar; the first main beam reinforcement bar includes a first inclined portion linearly extending from the upper end side of one beam end of the beam body to the lower end side of the other beam end of the beam body, and first parallel portions linearly extending outward from both ends of the first inclined portion substantially parallel to the central axis of the beam body; The second main beam reinforcement bar includes a second inclined portion extending linearly from the lower end side of one beam end of the beam body to the upper end side of the other beam end of the beam body, and second parallel portions extending linearly outward from both ends of the second inclined portion substantially parallel to the central axis of the beam body. The bending positions of the first main beam reinforcement bar and the second main beam reinforcement bar are inside the beam end face within the beam body. A beam member and a vertical member joint structure, characterized in that one or two bundled shear reinforcement bars are arranged between the bending position and the beam end face closer to the bending position.

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