Column capital construction

Abstract

To prevent interference with a gusset plate without substantially lowering structural performance.SOLUTION: An anchoring plate 41a has: a first end part which is placed on a flange 21 (an upper flange) of a beam 12a (a first steel beam); a second end part which is placed on the flange 21 (the upper flange) of a beam 12c (a second steel beam); a first insertion hole into which a main reinforcement 31b (a first main reinforcement) is inserted and fixed; a second insertion hole into which a main reinforcement 31c (a fourth main reinforcement) is inserted and fixed; and a third insertion hole into which a main reinforcement 31a (a fifth main reinforcement) is inserted and fixed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a column head structure of a column reinforced concrete-beam steel composite structure.

Background Art

[0002] Patent Document 1 discloses a column head structure of a column reinforced concrete-beam steel composite structure. Non-Patent Document 1 discloses an anchoring method for main reinforcement at the top floor of a precast reinforced concrete frame.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Non-Patent Literature

[0004]

Non-Patent Document 1

Summary of Invention

Problem to be Solved by the Invention

[0005] The column head structure of Patent Document 1 is provided with U-shaped anchoring reinforcing bars at the beam-column joint, so it cannot be applied to steel beams having gusset plates thereat. The anchoring method of Non-Patent Document 1 can also be applied to the case where the beam is a steel beam instead of a reinforced concrete beam, but since it uses a square-shaped anchoring plate, it still cannot be applied to steel beams having gusset plates. An object of the present invention is to solve such problems, for example.

Means for Solving the Problem

[0006] The column head structure is a reinforced concrete column having a first main reinforcement, a second main reinforcement arranged substantially parallel to the first main reinforcement, a third main reinforcement arranged substantially parallel to the first main reinforcement in a direction different from the second main reinforcement when viewed from the first main reinforcement, a fourth main reinforcement arranged substantially parallel to the first main reinforcement between the first and second main reinforcement, and a fifth main reinforcement arranged substantially parallel to the first main reinforcement between the first and third main reinforcement, and an upper flange joined to the top of the reinforced concrete column, extending through the space between the fourth main reinforcement and the second main reinforcement. The structure comprises a first steel beam, a second steel beam having an upper flange and joined to the top of the reinforced concrete column and the first steel beam, extending through the space between the fifth main reinforcement and the third main reinforcement, a first end placed on the upper flange of the first steel beam, a second end placed on the upper flange of the second steel beam, and an anchoring plate having a first insertion hole through which the first main reinforcement is inserted and anchored, a second insertion hole through which the fourth main reinforcement is inserted and anchored, and a third insertion hole through which the fifth main reinforcement is inserted and anchored. [Effects of the Invention]

[0007] According to the column head structure, interference with the gusset plate can be prevented without substantially reducing structural performance. [Brief explanation of the drawing]

[0008] [Figure 1] A plan view showing an example of a column capital structure. [Figure 2] A front view showing the aforementioned column capital structure. [Figure 3] Right side view showing the aforementioned column capital structure. [Figure 4] A plan view showing the column head structure of a comparative example. [Figure 5] A graph showing the load-deformation relationship of the column head structure. [Figure 6] A graph showing the strain distribution of the main reinforcement bars in the column head structure. [Figure 7] A graph showing the strain distribution of the main reinforcement bars in the column head structure. [Modes for carrying out the invention]

[0009] Referring to FIGS. 1 to 3, the column capital structure 10 is described. The column capital structure 10 is a structure used for a column-beam joint at the top of a column in a building having a mixed structure of reinforced concrete columns and steel beams. The column capital structure 10 includes, for example, beams 12a to 12c, a column 13, and a column-beam joint 14.

[0010] The column 13 is made of, for example, reinforced concrete, and extends generally in the ±Z direction. The column 13 includes, for example, main reinforcements 31a to 31l, hoops (not shown), and concrete 32 covering the peripheries of these components.

[0011] The main reinforcements 31a to 31l are arranged substantially parallel to each other, and extend generally in the ±Z direction. The ends (upper ends) on the +Z side of the main reinforcements 31a to 31l reach above the column-beam joint 14. The main reinforcement 31b (first main reinforcement) is arranged at the corner on the +X side and -Y side of the column 13. The main reinforcement 31e (second main reinforcement) is arranged at the corner on the +X side and +Y side of the column 13. The main reinforcement 31h (sixth main reinforcement) is arranged at the corner on the -X side and +Y side of the column 13. The main reinforcement 31k (third main reinforcement) is arranged at the corner on the -X side and -Y side of the column 13. The main reinforcement 31a (fifth main reinforcement) is arranged between the main reinforcement 31b and the main reinforcement 31k. The main reinforcement 31c (fourth main reinforcement) is arranged between the main reinforcement 31b and the main reinforcement 31e. The main reinforcement 31d (seventh main reinforcement) is arranged between the main reinforcement 31e and the main reinforcement 31c. The main reinforcement 31f (eighth main reinforcement) is arranged between the main reinforcement 31e and the main reinforcement 31h. The main reinforcement 31g is arranged between the main reinforcement 31h and the main reinforcement 31f. The main reinforcement 31i is arranged between the main reinforcement 31h and the main reinforcement 31k. The main reinforcement 31j is arranged between the main reinforcement 31k and the main reinforcement 31i. The main reinforcement 31l is arranged between the main reinforcement 31k and the main reinforcement 31a.

[0012] The beams 12a to 12c are made of, for example, H-shaped steel, and include flanges 21 and 22, a web 23 connecting the flanges, and a bearing plate 24.

[0013] The beam 12a is placed on the concrete 32 of the column 13, passes between the main reinforcement 31c and the main reinforcement 31d at the column-beam joint 14, passes between the main reinforcement 31i and the main reinforcement 31j, and extends substantially in the ±X direction. The beam 12b is placed on the concrete 32 of the column 13, passes between the main reinforcement 31f and the main reinforcement 31g at the column-beam joint 14, extends substantially in the ±Y direction, and has an end on the -Y side joined to the beam 12a. The beam 12c is placed on the concrete 32 of the column 13, passes between the main reinforcement 31a and the main reinforcement 31l at the column-beam joint 14, extends substantially in the ±Y direction, and has an end on the +Y side joined to the beam 12a. The beam 12a further includes a gusset plate 25. The gusset plate 25 is a flat plate substantially perpendicular to the ±Y direction, and protrudes in the +Z direction from the +Z-side surface (upper surface) of the +Z-side (upper) flange 21.

[0014] The column-beam joint 14 includes, for example, anchoring plates 41a to 41d, closing plates 42a to 42d, concretes 43a to 43d, and nuts 44a to 44l.

[0015] The anchoring plate 41a is, for example, a substantially L-shaped flat plate, and includes a first portion extending in the ±Y direction and a second portion extending in the -X direction from the -Y-side end of the first portion. The +Y-side end (first end) of the first portion is placed on the +Z-side surface (upper surface) of the +Z-side (upper) flange 21 of the beam 12a. The -X-side end (second end) of the second portion is placed on the +Z-side surface (upper surface) of the +Z-side (upper) flange 21 of the beam 12c. At the corner where the first and second parts connect, an insertion hole (first insertion hole) is provided through which the main reinforcement bar 31b is inserted. Furthermore, the first section is provided with an insertion hole (second insertion hole) through which the main reinforcement bar 31c is inserted, and the second section is provided with an insertion hole (third insertion hole) through which the main reinforcement bar 31a is inserted.

[0016] The fixing plate 41b (second fixing plate) is, for example, a flat plate with a roughly L-shape, and has a first portion extending in the ±Y direction and a second portion extending in the -X direction from the +Y end of the first portion. The -Y end (first end) of the first section rests on the +Z side (upper surface) of the flange 21 on the +Z side (upper side) of the beam 12a. The -X end (second end) of the second section rests on the +Z side (upper surface) of the flange 21 on the +Z side (upper side) of the beam 12b. At the corner where the first and second parts connect, through holes (first through holes) are provided through which the main reinforcement bars 31e are inserted. Furthermore, the first section is provided with an insertion hole (second insertion hole) through which the main reinforcement bar 31d is inserted, and the second section is provided with an insertion hole (third insertion hole) through which the main reinforcement bar 31f is inserted. The first portion of the fixing plate 41b and the first portion of the fixing plate 41a are arranged opposite each other in the ±Y direction with a gap between them, and the gusset plate 25 is positioned between them.

[0017] The fixing plate 41c is, for example, a flat plate with a substantially L-shape, and has a first portion extending in the ±Y direction and a second portion extending in the +X direction from the +Y end of the first portion. The -Y end (first end) of the first section rests on the +Z side (upper surface) of the flange 21 on the +Z side (upper side) of the beam 12a. The +X end (second end) of the second section rests on the +Z side surface (top surface) of the flange 21 on the +Z side (upper side) of the beam 12b. At the corner where the first and second parts connect, through-holes (first through-holes) are provided through which the main reinforcement bars 31h are inserted. Furthermore, the first section is provided with an insertion hole (second insertion hole) through which the main reinforcement bar 31g is inserted, and the second section is provided with an insertion hole (third insertion hole) through which the main reinforcement bar 31i is inserted. The second portion of the fixing plate 41c and the second portion of the fixing plate 41b are arranged opposite each other in the ±X direction with a gap between them.

[0018] The fixing plate 41d is, for example, a roughly L-shaped flat plate and has a first portion extending in the ±Y direction and a second portion extending in the +X direction from the -Y end of the first portion. The +Y side end (first end) of the first part rests on the +Z side surface (top surface) of the flange 21 on the +Z side (upper side) of the beam 12a. The +X end (second end) of the second part rests on the +Z side (upper surface) of the flange 21 on the +Z side (upper side) of the beam 12c. At the corner where the first and second parts connect, through-holes (first through-holes) are provided through which the main reinforcement bars 31k are inserted. Furthermore, the first section is provided with an insertion hole (second insertion hole) through which the main reinforcement bar 31j is inserted, and the second section is provided with an insertion hole (third insertion hole) through which the main reinforcement bar 31l is inserted. The first portion of the fixing plate 41d and the first portion of the fixing plate 41c are arranged opposite each other in the ±Y direction with a gap between them. The second portion of the fixing plate 41d and the second portion of the fixing plate 41a are arranged opposite each other in the ±X direction with a gap between them.

[0019] As such, there is a gap between the adjacent fixing plates 41a and 41b, so they do not interfere with the gusset plate 25.

[0020] The cover plates 42a to 42d are fixed to the beams 12a to 12c and rest on the concrete 32 of the column 13.

[0021] Nuts 44a to 44l are screwed into the male threads on the +Z side ends of the main reinforcing bars 31a to 31l, which are inserted into the insertion holes provided in the anchoring plates 41a to 41d, thereby applying tension to the main reinforcing bars 31a to 31l and anchoring them. Since the ends of the anchoring plates 41a to 41d are placed on the beams 12a to 12c, tension is applied evenly to the main reinforcement bars 31a to 31l inserted through the three insertion holes in each plate, thereby anchoring the main reinforcement bars 31a to 31l without tilting the anchoring plates 41a to 41d.

[0022] The concrete 43a to 43d is manufactured by first fixing the main reinforcement bars 31a to 31l with anchoring plates 41a to 41d and nuts 44a to 44d, and then pouring ready-mix concrete into the space enclosed by the +Z side (top surface) of the concrete 32 of the column 13, the inner surfaces of the cover plates 42a to 42d, and the beams 12a to 12c, and allowing it to solidify.

[0023] Referring to Figure 4, the column head structure 10Z in the comparative example will be explained. The column head structure 10Z has an anchoring plate 41Z instead of anchoring plates 41a to 41d. The anchoring plate 41Z is, for example, a roughly rectangular flat plate and has 12 insertion holes through which the main reinforcement bars 31a to 31l are inserted. Furthermore, a gusset plate 25 is not provided on beam 12a because it would interfere with the anchoring plate 41Z.

[0024] The results of the strength test will be explained with reference to Figures 5-7. Compared to the column head structure 10Z, the column head structure 10 has a fixed plate 41Z that is divided into four fixed plates 41a to 41d, which raises concerns about reduced structural performance. Therefore, test specimens using column head structures 10 and 10Z were fabricated, and strength tests were conducted.

[0025] In Figure 5, the horizontal axis represents deformation and the vertical axis represents load. "RCS21" shows the load-deformation relationship of column head structure 10Z, and "RCS22" shows the load-deformation relationship of column head structure 10. Figure 6 shows the strain distribution of the main reinforcement in the column head structure 10Z. Figure 7 shows the strain distribution of the main reinforcement bars in the column head structure 10.

[0026] As can be seen from these experimental results, regarding the load-deformation relationship, although there are some differences in initial stiffness, there are no significant differences in the yield deformation or maximum load-bearing capacity of the main reinforcement of the column, so there are no practical problems. As described above, by dividing the anchoring plate, interference with the gusset plate can be prevented without substantially reducing the structural performance.

[0027] The embodiments described above are examples intended to facilitate understanding of the present invention. The present invention is not limited thereto and includes various modifications, changes, additions, or deletions without departing from the scope defined by the appended claims. This will be readily apparent to those skilled in the art from the above description.

[0028] In a frame structure with a mixed RC column and S beam structure, when anchoring the main reinforcement of the top-floor columns using a square anchoring plate, interference with the gusset plate used for installing the brace becomes a problem. Therefore, by making the square anchoring plate a segmented type with a non-continuous shape from the start, constructability can be improved. Using a rectangular anchoring plate to anchor the main reinforcement of the top-floor columns allows for a shorter anchoring length, eliminating the need to protrude the column head concrete and resulting in a neater finish. However, interference with the gusset plate used for installing braces becomes a problem. By using a segmented, non-continuous rectangular anchoring plate and anchoring the main reinforcement of the column at each of the four corners, interference with the gusset plate can be avoided. Structural experiments have been conducted to confirm that there is no significant difference in the load-deformation relationship of the frame or the anchoring characteristics of the main reinforcement of the column between a conventional integrated rectangular anchoring plate and the proposed segmented rectangular anchoring plate. The rectangular anchoring plate retains the advantage of reducing the anchoring length of the main column reinforcement, while also avoiding interference with the gusset plate, thus improving workability and productivity. [Explanation of Symbols]

[0029] 10,10Z Column head structure, 12a~12c Beam, 13 Column, 14 Column-beam joint, 21,22 Flange, 23 Web, 24 Bearing plate, 25 Gusset plate, 31a~31l Main reinforcement, 32,43a~43d Concrete, 41a~41d,41Z Anchorage plate, 42a~42d Closing plate, 44a~44l Nut.

Claims

1. A reinforced concrete column having a first main reinforcement, a second main reinforcement arranged substantially parallel to the first main reinforcement, a third main reinforcement arranged substantially parallel to the first main reinforcement in a direction different from that of the second main reinforcement when viewed from the first main reinforcement, a fourth main reinforcement arranged substantially parallel to the first main reinforcement between the first and second main reinforcement, and a fifth main reinforcement arranged substantially parallel to the first main reinforcement between the first and third main reinforcement, Having an upper flange, a first steel beam is joined to the top of the reinforced concrete column and extends through the space between the fourth main reinforcement and the second main reinforcement, A second steel beam having an upper flange, joined to the top of the reinforced concrete column and the first steel beam, extending through the space between the fifth main reinforcement and the third main reinforcement, A fixing plate having a first end placed on the upper flange of the first steel beam, a second end placed on the upper flange of the second steel beam, a first insertion hole through which the first main reinforcement is inserted and fixed, a second insertion hole through which the fourth main reinforcement is inserted and fixed, and a third insertion hole through which the fifth main reinforcement is inserted and fixed, Equipped with, Stigma structure.

2. The reinforced concrete column has a sixth main reinforcement arranged substantially parallel to the second main reinforcement in a direction different from the first main reinforcement when viewed from the second main reinforcement, a seventh main reinforcement arranged substantially parallel to the second main reinforcement between the second main reinforcement and the fourth main reinforcement, and an eighth main reinforcement arranged substantially parallel to the second main reinforcement between the second main reinforcement and the sixth main reinforcement. A third steel beam having an upper flange, joined to the top of the reinforced concrete column and the first steel beam, extending through the space between the eighth main reinforcement and the sixth main reinforcement, A first end portion of the first steel beam is placed on the upper flange, a second end portion of the third steel beam is placed on the upper flange, and a second anchoring plate has a first insertion hole through which the second main reinforcement is inserted and anchored, a second insertion hole through which the seventh main reinforcement is inserted and anchored, and a third insertion hole through which the eighth main reinforcement is inserted and anchored. Equipped with, The column head structure according to claim 1.

3. The first steel beam has a gusset plate protruding from the upper surface of the upper flange, The first end of the second fixing plate is arranged opposite to the first end of the fixing plate, with the gusset plate in between. The column head structure according to claim 2.

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