Column joint structure, and construction method of column joint structure

Abstract

To provide column joint structure that is excellent in workability during construction by using a reinforcement arrangement not requiring a shear reinforcement inside a steel pipe in joint structure.SOLUTION: Column joint structure 1 that joins a column-beam joint portion 10 where a steel beam is joined to a steel pipe column 12 and a reinforced concrete column 30 comprises a cylindrical joint steel pipe portion 32, an annular horizontal fixing plate 34, and a plurality of vertical fixing plates 36a, 36b. The reinforced concrete column 30 comprises a plurality of main reinforcements 38a, 38b extending within the joint steel pipe portion 32. A lower surface of the horizontal fixing plate 34 is joined to upper ends of the vertical fixing plates 36a, 36b. The horizontal fixing plate 34 has a plurality of through holes 35a, 35b formed therein at intervals. The main reinforcements 38a, 38b pass through the through holes 35a, 35b and are integrated with the horizontal fixing plate 34 by concrete 17 poured inside the joint steel pipe portion 32.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a column joint structure formed by connecting a steel pipe column and a reinforced concrete column, and a method for constructing the column joint structure. [Background technology]

[0002] In recent years, RC (reinforced concrete) high-rise buildings have been adopted in many large-scale redevelopment projects. Many of these high-rise buildings are complex facilities intended for multiple uses. Different uses require different column spans and floor heights, and different structural types suitable for the framework are required depending on the use.

[0003] For example, lower floors may be used for stores and offices, which require a relatively large space with a large column span, while higher floors may be used for residences and hotels, which require a small column span and high rigidity and sound insulation. In such cases, steel frame construction or concrete filled steel tube construction may be used on the lower floors, and reinforced concrete construction may be used on the upper floors. In this way, it is necessary to switch the structural type of the framework at intermediate floors to create a rational structure that matches the facility's purpose.

[0004] Conventionally, joint structures have been proposed that connect steel or CFT columns to RC columns at intermediate floors like this (for example, Patent Documents 1 and 2). In the joint structure of Patent Document 1 between the connecting steel pipe extending upward from the CFT column and the RC column on the upper floor, the main reinforcement of the RC column is not directly connected to the connecting steel pipe, so stress is transferred via the concrete. In addition, in the joint structure of the CFT column and RC column in Patent Document 2, the main reinforcement of the RC column is extended beyond the column-beam joint to the top end of the CFT column and fixed with a plate nut, so stress is transferred via the concrete. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2022-557 [Patent Document 2] JP 2016-132948 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the joint structures of Patent Documents 1 and 2, the shear reinforcement bars are arranged all the way to the inside of the steel pipes, making it difficult to perform the work of placing the reinforcement bars.

[0007] Therefore, the present invention provides a column joint structure and a method for constructing a column joint structure that are excellent in workability during construction by using reinforcement inside the steel pipes in the joint structure that does not require shear reinforcement. [Means for solving the problem]

[0008] The present invention has been made to solve at least some of the above-mentioned problems, and can be realized in the following aspects or application examples.

[0009] [1] One aspect of the column joint structure according to the present invention is as follows: A column-beam joint structure that connects a steel beam to a steel pipe column and a reinforced concrete column, The joining structure is A cylindrical joint steel pipe portion protruding upward from the column-beam joint portion; An annular horizontal fixing plate protruding horizontally inward from the inner surface of the joint steel pipe portion; A plurality of vertical fixing plates protruding inward from the inner surface and extending in a vertical direction; Equipped with The reinforced concrete column includes a plurality of main reinforcements extending into the joint steel pipe portion, The horizontal fixing plate is provided near the upper end of the joint steel pipe portion, and a lower surface of the horizontal fixing plate is joined to the upper ends of the plurality of vertical fixing plates, The horizontal fixing plate has a plurality of through holes formed at intervals to match the positions of the plurality of main reinforcements, The through hole has an opening diameter larger than the maximum diameter of the main reinforcement, The multiple main reinforcements pass through the multiple through holes without being joined to the horizontal fixing plate by mechanical means, and are integrated with the horizontal fixing plate by concrete poured inside the connecting steel pipe section.

[0010] [2] In the column joint structure, The joining steel pipe portion has a substantially rectangular cross section, The plurality of main reinforcements include first main reinforcements arranged at each corner of the substantially rectangular joined steel pipe portion, and a plurality of second main reinforcements arranged between the first main reinforcements, The plurality of vertical fixing plates include a first vertical fixing plate disposed between the first main reinforcement and the second main reinforcement adjacent to the first main reinforcement, and a second vertical fixing plate disposed between adjacent second main reinforcements, The two first vertical fixing plates adjacent to each other across the first main reinforcement are arranged at a predetermined interval, The inner end of the first vertical fixed plate is located outside the inner peripheral edge of the annular horizontal fixed plate, The inner end of the second vertical fixed plate may extend to the inner peripheral edge of the annular horizontal fixed plate.

[0011] [3] In the column joint structure, The length from the lower surface of the horizontal fixing plate to the lower ends of the main reinforcements may be 30db or more (db is the diameter of the reinforcement bar).

[0012] [4] In the column joint structure, The lower ends of the multiple main reinforcements may contact an upper surface of the column-beam joint.

[0013] [5] One aspect of the method for constructing a column joint structure according to the present invention is to A method for constructing a column joint structure that connects a steel beam to a steel pipe column and a reinforced concrete column, comprising: A step of inserting a plurality of main reinforcements from above into a cylindrical joint steel pipe portion protruding upward from the column-beam joint portion; Pouring concrete into the joint steel pipe portion into which the plurality of main reinforcements are inserted; Including, The column joint structure includes an annular horizontal fixing plate protruding horizontally inward from the inner surface of the joint steel pipe section, and a plurality of vertical fixing plates protruding inward from the inner surface and extending vertically, The horizontal fixing plate is provided near the upper end of the joint steel pipe portion, and a lower surface of the horizontal fixing plate is joined to the upper ends of the plurality of vertical fixing plates, The horizontal fixing plate has a plurality of through holes formed at intervals to match the positions of the plurality of main reinforcements, The inserting step includes inserting the plurality of main reinforcements into the plurality of through holes without being joined to the horizontal fixing plate by a mechanical means, The pouring step is characterized in that the concrete poured into the joint steel pipe section integrates the multiple main reinforcements with the horizontal fixing plate. Effect of the Invention

[0014] According to the column joint structure and the method for constructing a column joint structure of the present invention, stress is transmitted to the connecting steel pipe section by the adhesion force between the main bars extending from the reinforced concrete column and the concrete inside the connecting steel pipe section, thereby eliminating the need for shear reinforcement in the connecting structure and improving workability during construction. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a longitudinal cross-sectional view showing a column joint structure according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view taken along the line AA in FIG. [Diagram 3] 2 is a cross-sectional view taken along line BB in FIG. [Figure 4] 1 is a graph showing the relationship between the column shear force of the test specimen and the column member angle when a tensile axial force equivalent to 0.5 times the tensile yield strength of a reinforced concrete column is applied. [Diagram 5] 1 is a graph showing the relationship between the column shear force of the test specimen and the column member angle when a compressive axial force equivalent to 0.25 times the compressive strength of a reinforced concrete column is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are necessarily essential components of the present invention.

[0017] 1. Column joint structure The column joint structure 1 according to this embodiment will be described below with reference to Fig. 1 to Fig. 3. Fig. 1 is a vertical cross-sectional view showing the column joint structure 1 according to this embodiment, Fig. 2 is a cross-sectional view taken along line AA in Fig. 1, and Fig. 3 is a cross-sectional view taken along line BB in Fig. 1. Fig. 1 also shows the cross-section taken along line CC in Fig. 2. In Fig. 2, the vertical fixing plates 36a, 36b below the horizontal fixing plate 34 are shown by dashed lines, and Figs. 1 to 3 show a state in which concrete 17 (shaded) has been poured inside the joint steel pipe portion 32.

[0018] 1 and 2, the column joint structure 1 according to this embodiment is a column joint structure 1 that joins a column-beam joint 10, at which a steel beam 14 is joined to a steel pipe column 12, to a reinforced concrete column 30. Buildings to which the joint structure 1 is applied include, for example, super-high rise buildings in which the structural type of the framework of the lower floor is different from the structural type of the framework of the upper floor. In this embodiment, an example of a building in which CFT construction is used for the lower floors and RC construction is used for the upper floors will be described, but S construction may be used for the lower floors instead of CFT construction.

[0019] The column-beam joint 10 constitutes a part of the CFT structure of the lower floor of the building, and includes a steel pipe column 12 having a cross section of, for example, a square tube shape extending downward from the column-beam joint 10, a plurality of steel beams 14 extending horizontally outward from the steel pipe column 12, and concrete 17 poured inside the steel pipe column 12. In this specification, unless otherwise specified, the "inside" refers to the central axis side of the joint structure 1, and the "outside" refers to the opposite. The steel pipe column 12 is provided on the inside of the upper end with a ring-shaped diaphragm 16 having a pouring hole 16a formed therein. Instead of the diaphragm 16, an outer diaphragm extending outward from the steel pipe column 12 may be provided. Although the square tube-shaped steel pipe column 12 is described in Figs. 2 and 3, the cross-sectional shape of the steel pipe column 12 may be cylindrical.

[0020] The reinforced concrete column 30 constitutes a part of the RC structure of the upper floor of the building. The reinforced concrete column 30 has a plurality of main reinforcements 38a, 38b (see FIG. 2 for 38a) extending inside the joint steel pipe section 32. The reinforced concrete column 30 also has hoops (not shown) arranged to enclose the main reinforcements 38a, 38b, and concrete 17. In FIG. 1, the concrete The area where the reinforcement bars 17 have been poured is shown shaded. Multiple main reinforcements 38a, 38b are arranged along the periphery of the reinforced concrete column 30. The multiple main reinforcements 38a, 38b extend in the direction along the Y-axis (vertical direction) within the reinforced concrete column 30. The main reinforcements 38a, 38b may be extended in the longitudinal direction by, for example, a joint portion 39. Although an example of the joint portion 39 is a mechanical joint, it may be any other known joint type.

[0021] The joint structure 1 includes a joint steel pipe section 32, a horizontal fixing plate 34, and a plurality of vertical fixing plates 36a, 36b. The horizontal fixing plate 34 and the vertical fixing plate 36 are sometimes called rib plates. The joint structure 1 is located between the column-beam joint 10 and the reinforced concrete column 30, and rationally connects different frame structures at a relatively short distance. In addition, the joint structure 1 does not affect the earthquake resistance of the reinforced concrete column 30. It is desirable to ensure a sufficient margin for the portion of the steel pipe column 12 below the column-beam joint 10 so that the destruction mode during a large earthquake is a bending yield mode of the portion of the reinforced concrete column 30. For example, it is preferable to ensure a margin of 1.3 times or more for the stress generated below the column-beam joint 10 when the reinforced concrete column 30 bends and yields.

[0022] The joining steel pipe section 32 is a cylindrical member protruding upward from the column-beam joint section 10. The joining steel pipe section 32 is, for example, a steel pipe. The lower end of the joining steel pipe section 32 is integrally joined to the column-beam joint section 10, and the upper end is open. As shown in FIG. 2, the joining steel pipe section 32 can have a substantially rectangular cross section. The joining steel pipe section 32 can have the same outer shape as the steel pipe column 12. In this embodiment, the joining steel pipe section 32 is an example of a rectangular tube having a substantially square cross section, but is not limited thereto, and may be, for example, rectangular or circular. The joining steel pipe section 32 can be made of the same material as the steel pipe used in the column-beam joint section 10 of the CFT structure. The horizontal fixing plate 34 and the vertical fixing plates 36a and 36b are welded to the inner surface 32a of the joining steel pipe section 32 and integrated. It is preferable for the welding work of the horizontal fixing plate 34 and the vertical fixing plates 36a, 36b to the joint steel pipe section 32 to be performed in a factory before being delivered to the construction site in terms of workability and efficiency. The joint steel pipe section 32 may be welded to the column-beam joint section 10 at the construction site, or may be assembled together with the column-beam joint section 10 at a factory and then delivered to the construction site. A plurality of main reinforcements 38a, 38b are provided extending from above inside the joint steel pipe section 32. The joint steel pipe section 32 and the main reinforcements 38a, 38b below the joint section 39 may be produced in a factory using precast concrete (PCa) and delivered to the construction site, in which case pouring holes for pouring concrete into the lower layer can be provided in the PCa.

[0023] The horizontal fixing plate 34 is an annular part that protrudes inward from the inner surface 32a of the joined steel pipe section 32 in the horizontal direction (direction along the X-axis). The horizontal fixing plate 34 is, for example, a steel plate. The horizontal fixing plate 34 is provided near the upper end of the joined steel pipe section 32, and the lower surface of the horizontal fixing plate 34 is joined to the upper ends of the multiple vertical fixing plates 36a, 36b to be integrated. "Near the upper end" refers to the highest position where the horizontal fixing plate 34 is placed on the upper end of the joined steel pipe section 32, and includes a distance of up to 150 mm from the upper end to the upper surface of the horizontal fixing plate 34. As shown in FIG. 2, the horizontal fixing plate 34 is formed along the inner surface 32a of the square-tube-shaped joined steel pipe section 32, so that it has a square opening in the center.

[0024] The horizontal fixing plate 34 has a plurality of through holes 35a, 35b formed at intervals to match the positions of the plurality of main reinforcements 38a, 38b. The through holes 35a, 35b have an opening diameter larger than the maximum diameter of the main reinforcements 38a, 38b. The plurality of main reinforcements 38a, 38b pass through the plurality of through holes 35a, 35b without being joined to the horizontal fixing plate 34 by mechanical means, and are integrated with the horizontal fixing plate 34 by the concrete 17 poured inside the connecting steel pipe section 32. Of the plurality of through holes 35a, 35b, a first through hole 35a is arranged at a corner when the connecting steel pipe section 32 is viewed from above, and a plurality of second through holes 35b are arranged between the first through hole 35a and the first through hole 35a. The plurality of second through holes 35b are arranged in a row along each side of the approximately rectangular connecting steel pipe section 32. The lower ends of the main reinforcements 38a, 38b are arranged at as low a position as possible in order to reduce the height of the joint steel pipe portion 32.

[0025] The joint steel pipe section 32 may be provided with a plurality of rib plates 32b protruding from the inner surface 32a. The rib plates 32b are thinner than the horizontal fixing plate 34 and have a smaller protruding width from the inner surface 32a. The rib plates 32b extend horizontally along each side of the substantially rectangular joint steel pipe section 32 and are fixed to the inner surface 32a by welding. The rib plates 32b are disposed below the horizontal fixing plate 34 and are provided in a plurality of stages at predetermined intervals in the vertical direction. The rib plates 32b are reinforcing ribs for preventing the concrete 17 from escaping from inside the joint steel pipe section 32.

[0026] The vertical fixing plates 36a, 36b protrude inward from the inner surface 32a of the joint steel pipe section 32 and extend in the vertical direction (direction along the Y axis). The vertical fixing plates 36a, 36b are, for example, steel plates. The outer ends of the vertical fixing plates 36a, 36b are welded to the inner surface 32a and fixed integrally with the joint steel pipe section 32. As shown in FIG. 1, the vertical fixing plates 36a, 36b are welded and fixed to the lower surface of the horizontal fixing plate 34. By fixing the vertical fixing plates 36a, 36b to the horizontal fixing plate 34, the pull-out force can be reliably transmitted to the joint steel pipe section 32. Therefore, when the main reinforcements 38a, 38b are subjected to stress in the vertical direction due to seismic motion, the concrete 17 attached to the main reinforcements 38a, 38b pushes up the horizontal fixing plate 34, suppressing the horizontal fixing plate 34 from deforming in the vertical direction, and preventing damage to the joint structure 1.

[0027] The multiple main reinforcements 38a, 38b include first main reinforcements 38a arranged at each corner of the joint steel pipe section 32, which is approximately rectangular in plan view, and multiple second main reinforcements 38b arranged between the first main reinforcements 38a, 38a. The first main reinforcements 38a are inserted into the first through holes 35a, and the second main reinforcements 38b are inserted into the second through holes 35b. The second main reinforcements 38b are arranged at equal intervals along each side of the approximately rectangular joint steel pipe section 32. In Figures 2 and 3, two first main reinforcements 38a, 38a are arranged on one side, and four second main reinforcements 38b are arranged between them, but the number of main reinforcements 38a, 38b is appropriately set depending on the thickness of the column and the purpose. The first main reinforcements 38a and the second main reinforcements 38b can both be made of reinforcement bars with the same diameter and length.

[0028] The vertical fixing plates 36a, 36b include a first vertical fixing plate 36a arranged between a first main reinforcement 38a and a second main reinforcement 38b adjacent to the first main reinforcement 38a, and a second vertical fixing plate 36b arranged between the adjacent second main reinforcements 38b, 38b. By arranging the first vertical fixing plate 36a facing the corner, it is possible to prevent the horizontal fixing plate 34 from turning up against the pulling force acting on the first main reinforcement 38a. It is preferable that the two first vertical fixing plates 36a, 36a adjacent to each other across the first main reinforcement 38a are arranged with a predetermined interval between them. In other words, since the two first vertical fixing plates 36a, 36a are arranged facing the corner of the joint steel pipe portion 32, which is approximately rectangular in plan view, leaving a predetermined interval between them makes it easier to fill the corner with concrete 17.

[0029] It is preferable that the inner end 37 of the second vertical fixing plate 36b is located up to the inner peripheral edge 34a of the annular horizontal fixing plate 34. The second vertical fixing plate 36b can reliably fix the horizontal fixing plate 34 over the entire depth. On the other hand, it is preferable that the inner end 37 of the first vertical fixing plate 36a is located outside the inner peripheral edge 34a of the annular horizontal fixing plate 34. In this way, even though the two first vertical fixing plates 36a, 36a narrow toward the inside, a gap can be provided between the closest inner end portions 37, 37, making it easy to fill the concrete 17 around the first main reinforcement 38a at the corner.

[0030] The length from the lower surface of the horizontal fixing plate 34 to the lower ends of the main reinforcements 38a, 38b can be 30db or more (db is the diameter of the reinforcement bar). If the joint length between b and the concrete 17 in the joint steel pipe part 32 is 30db or more, the joint steel pipe part 32 will not yield before the reinforced concrete column 30 yields in bending. Therefore, the yielding area can be intentionally controlled to be the reinforced concrete column 30 part. Also, according to the "Reinforcement bar joint" section of the "Guidelines for Reinforced Concrete Arrangement and Commentary" (Architectural Institute of Japan), this joint length (30db) is approximately the same as the "hook lap joint length" (30db) when using SD490, and sufficient bond strength can be ensured with a relatively short distance. The relationship between the reinforcing bar diameter and the preferred joint length is D25: 750mm, D29: 870mm, D32: 960mm, D35: 1050mm, D38: 1140mm, and D41: 1230mm. Furthermore, since the horizontal fixing plate 34 is provided near the upper end of the joining steel pipe section 32, the height of the joining steel pipe section 32 is the joining length plus the plate thickness of the horizontal fixing plate 34 and the height from the upper surface of the horizontal fixing plate 34 to the upper end of the joining steel pipe section 32 (for example, 150 mm or less is preferable).

[0031] It is preferable that the lower ends of the main reinforcements 38a, 38b contact the upper surface of the beam-column joint 10. In the example of Fig. 1, the lower ends of the main reinforcements 38a, 38b rest on the diaphragm 16. If the above 30db can be secured in this state, the height of the joint steel pipe section 32 can be reduced, resulting in excellent component costs and ease of construction. In particular, since there is no need to fix the long main reinforcements 38a, 38b within the joint steel pipe section 32, the main reinforcements 38a, 38b can be arranged as desired simply by inserting them in order into the through holes 35a, 35b of the horizontal fixing plate 34 during construction, resulting in excellent workability.

[0032] The lower ends of the main reinforcements 38a, 38b may be positioned higher than the upper surface of the diaphragm 16, in which case the main reinforcements 38a, 38b may be temporarily fastened near the through holes 35a, 35b during construction.

[0033] In this way, according to the joint structure 1, stress can be reliably transmitted to the joint steel pipe section 32 by the adhesive force between the main reinforcements 38a, 38b extending from the reinforced concrete column 30 and the concrete 17 inside the joint steel pipe section 32. Furthermore, shear reinforcement is not required inside the joint steel pipe section 32, improving workability during construction.

[0034] 2. Construction method of column joint structure A method for constructing a column joint structure 1 according to this embodiment will be described below with reference to Figs.

[0035] The construction method for the column joint structure 1 is a construction method for the column joint structure 1 described in the above embodiment (hereinafter referred to as the "construction method") for connecting a column-beam joint 10, in which a steel beam 14 is connected to a steel pipe column 12, to a reinforced concrete column 30. The construction method includes a step of inserting a plurality of main reinforcements 38a, 38b from above into a cylindrical joint steel pipe section 32 protruding upward from the column-beam joint 10, and a step of pouring concrete 17 into the joint steel pipe section 32 into which the plurality of main reinforcements 38a, 38b have been inserted.

[0036] As described above, the joint structure 1 includes the annular horizontal fixing plate 34 that protrudes horizontally inward from the inner surface 32a of the joint steel pipe section 32, and a plurality of vertical fixing plates 36a, 36b that protrude inward from the inner surface 32a and extend vertically. The horizontal fixing plate 34 is provided near the upper end of the joint steel pipe section 32, and the lower surface of the horizontal fixing plate 34 is joined to the upper ends of the plurality of vertical fixing plates 36a, 36b. The horizontal fixing plate 34 has a plurality of through holes 35a, 35b formed at intervals from each other that fit the positions of the plurality of main reinforcements 38a, 38b.

[0037] In the insertion step, the plurality of main reinforcements 38a, 38b are inserted into the plurality of through holes 35a, 35b, respectively, without being mechanically joined to the horizontal fixing plate 34. From the viewpoint of workability, it is preferable to insert the main reinforcements 38a, 38b until the lower ends of the main reinforcements 38a, 38b contact the top of the diaphragm 16. Since it is only necessary to insert the main reinforcements 38a, 38b into the through holes 35a, 35b, alignment is easy and workability is excellent. Also, since there is no vertical fixing plate on the upper surface side of the horizontal fixing plate 34, there is nothing to get in the way when moving the long main reinforcements 38a, 38b laterally on the horizontal fixing plate 34 to align them with the positions of the through holes 35a, 35b, and workability is excellent.

[0038] In the pouring process, the concrete 17 poured into the joint steel pipe portion 32 integrates the multiple main reinforcements 38a, 38b with the horizontal fixing plate 34. Since there is no need to mechanically fix the main reinforcements 38a, 38b to the horizontal fixing plate 34, this process is easy to work with.

[0039] According to this construction method, stress can be transmitted to the joint steel pipe section 32 by the adhesion between the main reinforcements 38a, 38b extending from the reinforced concrete column 30 and the concrete 17 inside the joint steel pipe section 32. This makes shear reinforcement unnecessary inside the joint steel pipe section 32, improving workability during construction. EXAMPLES

[0040] A static repeated loading experiment was carried out using a test specimen employing the joint structure 1 of the above-mentioned embodiment. The following will be described using the reference characters in Figs.

[0041] (Test specimen) A test specimen was produced in which a reinforced concrete column 30 with a height of 3,300 mm was constructed between two CFT-structured beam-column joints 10 provided at the top and bottom. A joint steel pipe section 32 (height 900 mm x width 640 mm x depth 640 mm) with a square cross section was welded to one of the beam-column joints 10, and the joint structure 1 was combined with the joint steel pipe section 32. A horizontal fixing plate 34 was welded to the joint steel pipe section 32 at a position 102 mm from the upper surface of the beam-column joint 10. In addition, eight first vertical fixing plates 36a and sixteen second vertical fixing plates 36b extending in the vertical direction were welded to the inner surface 32a of the lower surface of the horizontal fixing plate 34. Rib plates 32b were welded in six stages in the vertical direction to each side of the inner surface 32a. The lower ends of all the main reinforcements 38a, 38b were placed on the diaphragm 16 with the horizontal fixing plate 34 penetrating the lower end. The joining steel pipe section 32 had a height of 400 mm, a width and depth of 704 mm, and a plate thickness of 32 mm, the horizontal fixing plate 34 had a central opening measuring 440 x 440 mm, a width and depth of 640 mm, and a plate thickness of 28 mm, the first vertical fixing plate 36a had a height of 300 mm, a plate thickness of 12 mm, and a depth of 50 mm, the second vertical fixing plate 36b had a height of 300 mm, a plate thickness of 12 mm, and a depth of 100 mm, and the rib plate 32b had a depth of 20 mm and a plate thickness of 12 mm.

[0042] The horizontal fixing plate 34 had 24 through holes 35a, 35b corresponding to the 24 main reinforcements 38a, 38b. Among them, the 13 through holes 35a, 35b on the right side of the horizontal fixing plate 34 when viewed from the front were used as examples in which the main reinforcements 38a, 38b were not fixed, and the 11 through holes 35a, 35b on the left side were used as reference examples in which the main reinforcements 38a, 38b were fixed with fixing plates.

[0043] (Experimental conditions) The specimen was subjected to repeated horizontal loading tests with axial forces of +3089kN (tensile axial force: equivalent to 0.5 times the tensile yield strength of the reinforced concrete column 30) and -6943kN (compressive axial force: equivalent to 0.25 times the compressive strength of the reinforced concrete column 30) kept constant while gradually increasing the deformation angle. Horizontal loading was controlled for displacement based on the column member angle (=δ / h) calculated by dividing the horizontal displacement δ at the center of the loaded beam by the height h from the top of the lower stub to the bottom of the upper stub.

[0044] (Experimental Results) The experimental results are shown in Figures 4 and 5. Figure 4 shows the results of a test with a tensile axial force of 3089 kN. Fig. 5 is a graph showing the relationship between the column shear force and the column angle of the test specimen under a compressive axial force of 6943 kN. The vertical axis of each graph is the column shear force (kN), and the horizontal axis is the column angle (×10 -3 rad).

[0045] The dashed lines in each figure are the calculated bending strength of the reinforced concrete column 30. The experimental values ​​of the column shear force shown in each graph exceeded the calculated bending strength of the reinforced concrete column 30, and the column joint structure 1 did not affect the seismic strength of the reinforced concrete column 30. Furthermore, the joint structure 1 was not damaged throughout the experiment.

[0046] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the present invention includes configurations that are substantially the same as those described in the embodiments (for example, configurations with the same functions, methods, and results, or configurations with the same purpose and effect). The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects as the configurations described in the embodiments, or configurations that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments. [Explanation of symbols]

[0047] 1...column joint structure, 10...column beam joint, 12...steel pipe column, 14...steel beam, 16...diaphragm, 16a...casting hole, 17...concrete, 30...reinforced concrete column, 32...joint steel pipe section, 32a...inner surface, 32b...rib plate, 34...horizontal fixing plate, 34a...inner periphery, 35a...first through hole, 35b...second through hole, 36a...first vertical fixing plate, 36b...second vertical fixing plate, 37...inner end, 38a...first main bar, 38b...second main bar, 39...joint section

Claims

1. A column-beam joint structure that connects a steel beam to a steel pipe column and a reinforced concrete column, The joining structure is A cylindrical joint steel pipe portion protruding upward from the column-beam joint portion; An annular horizontal fixing plate protruding horizontally inward from the inner surface of the joint steel pipe portion; A plurality of vertical fixing plates protruding inward from the inner surface and extending in a vertical direction; Equipped with The reinforced concrete column includes a plurality of main reinforcements extending into the joint steel pipe portion, The horizontal fixing plate is provided near the upper end of the joint steel pipe portion, and a lower surface of the horizontal fixing plate is joined to the upper ends of the plurality of vertical fixing plates, The horizontal fixing plate has a plurality of through holes formed at intervals to match the positions of the plurality of main reinforcements, The through hole has an opening diameter larger than the maximum diameter of the main reinforcement, A column joint structure in which the multiple main reinforcements pass through the multiple through holes without being joined to the horizontal fixing plate by mechanical means, and are integrated with the horizontal fixing plate by concrete poured inside the connecting steel pipe section.

2. The column joint structure according to claim 1, The joining steel pipe portion has a substantially rectangular cross section, The plurality of main reinforcements include first main reinforcements arranged at each corner of the substantially rectangular joined steel pipe portion, and a plurality of second main reinforcements arranged between the first main reinforcements, The plurality of vertical fixing plates include a first vertical fixing plate disposed between the first main reinforcement and the second main reinforcement adjacent to the first main reinforcement, and a second vertical fixing plate disposed between the adjacent second main reinforcements, The two first vertical fixed plates adjacent to each other across the first main reinforcement are arranged at a predetermined interval, An inner end portion of the first vertical fixed plate is located outside an inner peripheral edge of the annular horizontal fixed plate, A column joint structure in which the inner end of the second vertical fixed plate extends to the inner peripheral edge of the annular horizontal fixed plate.

3. The column joint structure according to claim 1, A column joint structure, wherein the length from the lower surface of the horizontal fixed plate to the lower ends of the multiple main reinforcements is 30 db or more (db is the diameter of the reinforcement bar).

4. The column joint structure according to claim 3, A column joint structure in which the lower ends of the multiple main reinforcements contact the upper surface of the column-beam joint.

5. A method for constructing a column joint structure that connects a steel beam to a steel pipe column and a reinforced concrete column, comprising: A step of inserting a plurality of main reinforcements from above into a cylindrical joint steel pipe portion protruding upward from the column-beam joint portion; Pouring concrete into the joint steel pipe portion into which the plurality of main reinforcements are inserted; Including, The column joint structure includes an annular horizontal fixing plate protruding horizontally inward from the inner surface of the joint steel pipe section, and a plurality of vertical fixing plates protruding inward from the inner surface and extending vertically, The horizontal fixing plate is provided near the upper end of the joint steel pipe portion, and a lower surface of the horizontal fixing plate is joined to the upper ends of the plurality of vertical fixing plates, The horizontal fixing plate has a plurality of through holes formed at intervals to match the positions of the plurality of main reinforcements, The inserting step includes inserting the plurality of main reinforcements into the plurality of through holes without being joined to the horizontal fixing plate by a mechanical means, The pouring step is a method for constructing a column joint structure, in which the concrete poured into the joint steel pipe section integrates the multiple main reinforcements with the horizontal fixing plate.

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