JP2017053101A - Design method for structure for joining columns together, and structure for joining columns together - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a design method for a structure for joining columns together, which can suppress out-of-plane buckling without having a corner part provided with a rib, and a structure for joining the columns together.SOLUTION: In a structure for joining columns together, ribs 51 and 52 are provided to protrude in a horizontal direction from each inner peripheral surface of a steel pile 50, in a part except a corner part, in upper and lower vertical parts of the steel pipe 50. The protrusion length of the rib 51 from the inner peripheral surface is set to satisfy conditional expressions (1)-(5).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for designing a junction structure between columns and a junction structure between columns.

2. Description of the Related Art Conventionally, a composite structure building in which columns of different structures are joined together, such as a building in which reinforced concrete columns and concrete-filled steel pipe columns are joined in a vertical direction, is known. As such a composite structure building, a lower layer part having a reinforced concrete column, a boundary layer composed of one layer height disposed above the lower layer part, and a filled steel pipe concrete column disposed above the boundary layer And an upper layer portion having a structure has been proposed (see Patent Document 1 below).
The boundary layer in the above-mentioned composite structure building includes a steel pipe that forms an outer shell, a main reinforcement inserted into the steel pipe, a strip wound around the main reinforcement, and concrete filled in the steel pipe. Yes. Moreover, the rib which protrudes inward is provided in the upper end part and lower end part of the internal peripheral surface of a steel pipe over the perimeter along the internal peripheral surface of a steel pipe. In the said structure, the structure of an upper layer part and the structure of a lower layer part can be switched by the boundary layer only for one layer, such as an underground floor.

JP 2013-181350 A

  Here, in the composite structure building described in Patent Document 1, ribs are provided over the entire circumference along the inner circumferential surface of the steel pipe having a rectangular shape in plan view. When providing ribs along a complicated shape such as a curved shape, it is necessary to process the ribs along these shapes. However, it is difficult to process the rib or weld the rib along the shape of the corner portion of the steel pipe. For this reason, the structure which can suppress out-of-plane buckling without providing a rib in a corner part is desired.

  Accordingly, the present invention has been made in view of the above circumstances, and a method for designing a column-to-column junction structure that can suppress out-of-plane buckling without providing ribs at corners, and column-to-column junctions. Provide structure.

ただし、
Ｍ_Ｃ：鋼管の平面視一辺の中央部分の曲げモーメント
ｗ：第二柱に作用するせん断力の支圧反力
Ｂ_Ｃ：鋼管の平面視一辺の内法長さ
Ｗ：支圧反力ｗの作用領域高さ
ｔ_ＦＢ：鋼管の内周面からのリブ突出長さ
_ｅｑｔ：支圧反力ｗの作用領域高さにおけるｔ_ＦＢを考慮した鋼管の等価厚さ
ｔ_Ｐ：鋼管の厚さ
_ｅｑＺ：Ｗと_ｅｑｔとで構成される断面係数
σ_Ｃ：Ｗと_ｅｑｔとで構成される断面を有する鋼管の平面視一辺の中央部分の曲げ応力度
Ｆ：鋼管を形成する鋼材のＦ値 In order to achieve the above object, the present invention employs the following means.
That is, the method for designing a column-to-column connection structure according to the present invention includes a first column of a reinforced concrete structure having a concrete part and a column main reinforcing bar extending vertically in the concrete part, and a steel frame disposed above the first column. In designing a joint structure between columns that join a second column made of steel or filled steel pipe concrete, the first column and the second column are joined via a stress switching unit, and the stress switching unit Is disposed on the outer peripheral side of the lower part of the second column and the lower part of the second column, and extends continuously from the column main reinforcement and extends in the vertical direction from the concrete part, and all the main reinforcement parts. A steel pipe having a rectangular shape in plan view, which is disposed over the entire length in the vertical direction, and a filled concrete portion filled in the steel pipe. Other than department The ribs are provided so as to protrude horizontally from the respective inner peripheral surfaces of the steel pipe, and the protruding length of the ribs from the inner peripheral surface satisfies the following conditional expressions (1) to (5): It is characterized by setting as follows.

However,
M _C: viewed bending moment of the center portion of one side w of steel: the Bearing reaction forces w: Second Bearing reaction forces of shear forces acting on the pillar B _C: in plan view one side of the steel pipe inner size length W Working region height t _FB : Rib protrusion length from the inner peripheral surface of the steel pipe
_eq t: Equivalent thickness of the steel pipe in consideration of t _FB at the working region height of the bearing reaction force w t _P : Thickness of the steel pipe
_eq Z: Section modulus composed of W and _eq t σ _C : Bending stress degree at the center of one side of a steel pipe having a section composed of W and _eq t in plan view F: F of steel material forming the steel pipe value

ただし、
Ｍ_Ｃ：鋼管の平面視一辺の中央部分の曲げモーメント
ｗ：第二柱に作用するせん断力の支圧反力
Ｂ_Ｃ：鋼管の平面視一辺の内法長さ
Ｗ：支圧反力ｗの作用領域高さ
ｔ_ＦＢ：鋼管の内周面からのリブ突出長さ
_ｅｑｔ：支圧反力ｗの作用領域高さにおけるｔ_ＦＢを考慮した鋼管の等価厚さ
ｔ_Ｐ：鋼管の厚さ
_ｅｑＺ：Ｗと_ｅｑｔとで構成される断面係数
σ_Ｃ：Ｗと_ｅｑｔとで構成される断面を有する鋼管の平面視一辺の中央部分の曲げ応力度
Ｆ：鋼管を形成する鋼材のＦ値 In addition, the column-to-column connection structure according to the present invention includes a first column of reinforced concrete having a concrete portion and a column main reinforcing bar extending vertically in the concrete portion, and a steel structure or filling disposed above the first column. It is a joining structure of columns that join the second column of the steel pipe concrete structure, and the first column and the second column are joined via a stress switching unit, and the stress switching unit is A lower part of the second pillar, an outer peripheral side of the lower part of the second pillar, continuous with the pillar main bars and extending in the vertical direction from the concrete part, and surrounding all the main bars. A steel pipe having a rectangular shape in plan view disposed over the entire length in the vertical direction, and a filled concrete portion filled in the steel pipe, and the upper and lower portions of the steel pipe in the vertical direction other than corner portions In each part of the steel pipe A rib is provided so as to protrude in a horizontal direction from the surface, and a protruding length of the rib from the inner peripheral surface is set so as to satisfy the following conditional expressions (6) to (10). And

However,
M _C: viewed bending moment of the center portion of one side w of steel: the Bearing reaction forces w: Second Bearing reaction forces of shear forces acting on the pillar B _C: in plan view one side of the steel pipe inner size length W Working region height t _FB : Rib protrusion length from the inner peripheral surface of the steel pipe
_eq t: Equivalent thickness of the steel pipe in consideration of t _FB at the working region height of the bearing reaction force w t _P : Thickness of the steel pipe
_eq Z: Section modulus composed of W and _eq t σ _C : Bending stress degree at the center of one side of a steel pipe having a section composed of W and _eq t in plan view F: F of steel material forming the steel pipe value

In the design method of the column-to-column connection structure and the column-to-column structure configured as described above, the main bar portion of the first column and the lower portion of the second column are fixed to the filled concrete portion filled in the steel pipe. Thus, the first column and the second column are joined via the stress switching unit. Moreover, the rib which suppresses an out-of-plane buckling is provided in the both ends of the perpendicular direction of the steel pipe arrange | positioned at the outer peripheral side of the 2nd pillar. The ribs are formed from the inner peripheral surface of the steel pipe so that the conditional expressions (1) to (5) are satisfied, that is, the bending stress of the central portion on one side of the steel pipe is equal to or less than the F value of the steel material. Determine the protrusion length. Therefore, the steel pipe is reinforced with ribs, and out-of-plane buckling is suppressed.
In addition, the ribs are not provided at the corners of the steel pipe, but are provided along the flat part of the steel pipe having a rectangular shape in plan view. Therefore, the processing of the rib and the fixing to the steel pipe can be easily performed. can do.

  Further, in the joint structure between columns according to the present invention, the corner portion has a stiffening portion that connects the one inner peripheral surface and the other inner peripheral surface intersecting the one inner peripheral surface. It may be provided.

In the joint structure between the columns configured as described above, a stiffening portion that connects one inner peripheral surface and another inner peripheral surface is provided at a corner portion. Therefore, since one inner peripheral surface and the other inner peripheral surface are connected by the stiffening portion and the corner portion is reinforced, out-of-plane buckling of the corner portion can be suppressed.
In addition, the stiffening portion is configured to connect one inner peripheral surface and another inner peripheral surface, and since the shape and the like can be determined as appropriate, the processing of the stiffening portion can be facilitated.

  Moreover, the column-to-column connection structure according to the present invention includes a first column of reinforced concrete having a concrete portion and a column main reinforcing bar extending in the vertical direction in the concrete portion, and a steel structure or filling disposed above the first column. It is a joining structure of columns that join the second column of the steel pipe concrete structure, and the first column and the second column are joined via a stress switching unit, and the stress switching unit is A lower part of the second pillar, an outer peripheral side of the lower part of the second pillar, continuous with the pillar main bars and extending in the vertical direction from the concrete part, and surrounding all the main bars. A steel pipe having a rectangular shape in plan view disposed over the entire length in the vertical direction, and a filled concrete portion filled in the steel pipe, and the upper and lower portions of the steel pipe in the vertical direction other than corner portions In each part of the steel pipe Ribs are formed so as to protrude from the surface, and the corner portion is provided with a stiffening portion that connects the one inner peripheral surface and the other inner peripheral surface intersecting the one inner peripheral surface. It is characterized by.

  In the joining structure of the columns configured as described above, the first column and the second column are established by fixing the main reinforcement portion of the first column and the lower portion of the second column to the filled concrete portion filled in the steel pipe. Are joined via the stress switching part. Moreover, the rib which suppresses out-of-plane buckling is provided in the upper part and the lower part of the perpendicular direction of the steel pipe arrange | positioned at the outer peripheral side of the 2nd pillar. In addition, the corner portion is not provided with a rib, and is provided with a stiffening portion that connects one inner peripheral surface and another inner peripheral surface. Therefore, since one inner peripheral surface and the other inner peripheral surface are connected by the stiffening portion and the corner portion is reinforced, out-of-plane buckling of the corner portion can be suppressed.

  According to the column-to-column junction structure design method and the column-to-column junction structure according to the present invention, out-of-plane buckling can be suppressed without providing ribs at the corners.

It is a schematic front view which shows the joining structure of the pillars which concern on 1st embodiment of this invention. It is a longitudinal cross-sectional view which shows the structure of the junction structure of the pillar which concerns on 1st embodiment of this invention. It is AA sectional drawing of FIG. FIG. 3 is a longitudinal sectional view showing an action region height W of a bearing reaction force w in a column-to-column junction structure according to the first embodiment of the present invention. It is BB sectional drawing of FIG. It is a figure which shows the bending stress state by the bearing pressure reaction force which acts on the steel pipe upper part with respect to the assumed shear force in the junction structure of the columns which concern on 1st embodiment of this invention. It is a schematic front view which shows the joining structure of the pillars which concern on the modification of 1st embodiment of this invention. It is a longitudinal cross-sectional view which shows the structure of the junction structure of the pillar which concerns on 2nd embodiment of this invention. It is CC sectional drawing of FIG. It is a longitudinal cross-sectional view which shows the junction structure of the pillars which concern on the modifications 1 and 2 of 2nd embodiment of this invention. It is DD sectional drawing of FIG. 10 in the modification 1 of 2nd embodiment of this invention. It is DD sectional drawing of FIG. 10 in the modification 2 of 2nd embodiment of this invention. It is a figure used in order to calculate the arrangement | positioning range of the stiffening part of the joining structure of the columns which concern on the modification 1 of the 2nd embodiment of this invention, and the modification 2. FIG.

(First embodiment)
The building which concerns on 1st embodiment of this invention is demonstrated using drawing.
FIG. 1 is a schematic front view showing a joining structure between columns according to the first embodiment of the present invention. In the following drawings, in order to make the configuration easy to understand, a portion to be indicated by a broken line may be indicated by a solid line.
As shown in FIG. 1, a building 100 according to this embodiment includes a first column 1 made of reinforced concrete, a floor slab F0 on the first basement floor provided at the upper end of the first column 1, and a first column 1. And a second column 2 made of filled steel pipe concrete. Furthermore, the building 100 includes a third pillar 3 disposed above the second pillar 2, a floor slab F1 on the ground floor extending horizontally from the joint between the second pillar 2 and the third pillar 3, and reinforced concrete. Or a steel beam (not shown).

  The 1st pillar 1 and the 2nd pillar 2 are joined via the stress switching part 5 mentioned later (joint structure of pillars). The first pillar 1 is a second-floor pillar, the lower part of the stress switching portion 5 and the second pillar 2 is a first-floor pillar, and the third pillar 3 is a first-floor pillar.

(First pillar)
FIG. 2 is a longitudinal sectional view showing a configuration of a joining structure between columns. FIG. 3 is a cross-sectional view taken along the line AA of FIG.
As shown in FIGS. 2 and 3, the first pillar 1 has a plurality of main reinforcing bars 10 extending in the vertical direction with a predetermined interval in the horizontal direction, and a vertical interval so as to bundle the plurality of main reinforcing bars 10. A plurality of hoops 12 disposed and a first concrete portion 13 that is concrete filled in a substantially rectangular shape in plan view so as to cover the plurality of main bars 10 and the plurality of hoops 12. Yes.

  The plurality of main bars 10 are arranged at intervals inward of the outer peripheral surface so as to follow the outer peripheral surface of the first concrete portion 13 in plan view. The main muscle 10 extends to the upper part of the section X and the section X. Of the main reinforcement 10, a portion arranged in the section X is a column main reinforcement 11, and a portion arranged above the section X is a main reinforcement 70 constituting a stress switching unit 5 described later. That is, the column main reinforcement 11 and the main reinforcement 70 are continuously formed of, for example, steel bars for reinforced concrete.

  Further, the band 12 is arranged in the horizontal direction over the range of the section X. That is, the band 12 is wound around the column main bar 11 of the main bars 10.

  Further, the first concrete portion 13 is filled in the range of the section X. That is, the main reinforcement 70 protrudes upward from the upper surface of the first concrete part 13.

(Second pillar)
The second column 2 is disposed over a vertical section Y located above the section X, and is a square tube-shaped steel pipe (hereinafter referred to as a square steel pipe) 21 and a concrete filled in the square steel pipe 21. And a concrete portion 22.
In addition, the steel pipe 21 of the 2nd pillar 2 is not restricted to a rectangular tube shape, A cylindrical shape may be sufficient and the said shape can be selected suitably.

  The second column 2 is arranged inward of the first column 1 in plan view so that each side of the second column 2 is parallel to each side of the first column 1.

  A base plate 23 having a substantially rectangular shape in plan view is provided at the lower end of the square steel pipe 21. The outline of the base plate 23 in plan view is larger than the outline of the square steel pipe 21 in plan view and smaller than the outline of the first column 1 in plan view.

  Further, a substantially circular opening 23A penetrating in the vertical direction is formed in a substantially central portion of the base plate 23 in plan view.

  The square steel pipe 21 of the second pillar 2 is arranged over the range of the section Y. The second concrete portion 22 is filled over the section Y.

(Stress switching part)
The stress switching unit 5 is disposed over a section Z extending from the upper end of the section X to the lower portion of the section Y. The stress switching part 5 includes a lower part 2A of the second pillar 2, a main reinforcing part 70 of the main reinforcing part 10 of the first pillar 1 arranged on the outer peripheral side of the lower part 2A, and a joint steel pipe ( Steel pipe) 50 and a filled concrete portion 80 filled in the bonded steel pipe 50.

  The lower part 2 </ b> A of the second pillar 2 is a part arranged in the section Z of the second pillar 2. Further, the main reinforcement portion 70 is a portion of the main reinforcement 10 of the first pillar 1 that protrudes upward from the upper surface of the first concrete portion 13 and extends in the vertical direction, that is, a portion disposed in the section Z. The main bar portion 70 is higher than the lower end portion (base plate 23) of the second pillar 2 and extends to a position lower than the upper end portion of the section Z.

  The joining steel pipe 50 is a square tubular steel pipe extending in the vertical direction. The bonded steel pipe 50 is disposed over the entire length in the vertical direction, that is, over the entire length of the section Z.

  The outer shape in plan view of the bonded steel pipe 50 is substantially the same as the outer shape in plan view of the first column 1. Further, the bonded steel pipe 50 is disposed in contact with the upper side of the first column 1 so that the outer peripheral surface of the bonded steel pipe 50 is flush with the outer peripheral surface of the first column 1.

Further, the outer shape in plan view of the bonded steel pipe 50 is larger than the outer shape in plan view of the second pillar 2. That is, the lower part 2 </ b> A of the second pillar 2 is disposed inside the bonded steel pipe 50.
In this way, the bonded steel pipe 50 is disposed from the upper end portion of the first column 1 to the lower portion of the second column 2.

  Ribs 51 and 52 are provided on the upper and lower portions of the bonded steel pipe 50 so as to protrude from the inner peripheral surface 50N of the bonded steel pipe 50, respectively. The ribs 51 and 52 are provided on four surfaces forming the bonded steel pipe 50, respectively. The ribs 51 and 52 are provided along the inner peripheral surface 50N of the bonded steel pipe 50, and are not provided in the corner portion S of the bonded steel pipe 50 in plan view. Out-of-plane buckling of the bonded steel pipe 50 is prevented by the rib 51 provided on the upper part of the bonded steel pipe 50.

  The upper rib 51 of the bonded steel pipe 50 is provided so that the position of the upper end 51T of the rib 51 is aligned with the upper end 50T of the bonded steel pipe 50. The lower rib 52 of the bonded steel pipe 50 is provided so that the position of the lower end 52B of the rib 52 is aligned with the lower end 50B of the bonded steel pipe 50. In addition, the ribs 51 and 52 should just be provided in the upper part and the lower part of the joining steel pipe 50, respectively, and may be provided below the upper end part 50T and above the lower end part 50B.

  The ribs 51 and 52 have a function of preventing the joining steel pipe 50 from being deformed against a support pressure acting on the joining steel pipe 50 by an input shear force from the second column 2.

  The filled concrete portion 80 is concrete filled inside the bonded steel pipe 50 and outside the square steel pipe 21 of the second column 2 over the entire length of the bonded steel pipe 50. In this embodiment, fiber reinforced concrete is adopted, but ordinary concrete may be used. Fiber reinforced concrete is a concrete material in which synthetic fiber, steel fiber, or the like is combined with concrete.

In this embodiment, for example, steel fibers having a density of 7.85 g / cm ³ , a tensile strength of 700 N / mm ² , a length of 30 mm, and a diameter of 0.6 mm are employed as the fibers. Moreover, the mixing rate of this fiber is a maximum of 0.75 vol. %.

  The bearing strength of this fiber reinforced concrete is determined by the area ratio and is approximately 1.3 times the bearing strength of plain concrete. Moreover, the compressive strength of fiber reinforced concrete is about 1.0 to 1.1 times the compressive strength of plain concrete.

  In addition, in this embodiment, the 1st pillar 1, the 2nd pillar 2, and the stress switching part 5 are each comprised with the precast concrete member. When fiber reinforced concrete is used as the concrete constituting the filled concrete portion 80, a part of the fiber reinforced concrete is also present inside the second pillar 2 through the opening 23 </ b> A formed in the base plate 23 of the second pillar 2. Filled.

  That is, all or a part of the second concrete portion 22 of the second pillar 2 and the filled concrete portion 80 are integrally formed of fiber reinforced concrete or ordinary concrete. In addition, when precasting the 2nd pillar 2 and the stress switching part 5, in order to join the column main reinforcement 10 and the main reinforcement 70 of the 1st pillar 1 mechanically, it is to the lower end part 50B of the joining steel pipe 50. A mechanical joint is buried in advance so as to follow.

Next, a method for designing the ribs 51 and 52 in the above-described joint structure between columns will be described.
FIG. 4 is a longitudinal cross-sectional view showing an action region height W of the supporting reaction force w in the column-to-column connection structure according to the first embodiment of the present invention. 5 is a cross-sectional view taken along the line BB in FIG. FIG. 6 is a diagram showing a bending stress state due to a bearing reaction force acting on an upper portion of a steel pipe with respect to an assumed shear force in the column-to-column connection structure according to the first embodiment of the present invention.
The ribs 51 and 52 are set so as to satisfy the following conditional expression.
In the above-described joining structure, the bearing reaction force w of the shearing force acting on the second column 2 acts on the region of B _C × W, and bending stress as shown in FIG. 6 acts on one side of the joining steel pipe 50 in plan view. I think it is.
At this time, bending moment M _C of B _C center section (viewed from the central portion of one side of the joining steel pipe 50) is expressed by the following conditional expression (1).

The equivalent thickness _eq t of the bonded steel pipe 50 in consideration of the protruding length of the ribs 51 and 52 from the inner peripheral surface 50N of the bonded steel pipe 50 in the W region is expressed by the following conditional expression (2).

The section modulus _eq Z composed of W and _eq t at this time is expressed by the following conditional expression (3).

Therefore, the bending stress σ _C of the central portion of one side in a plan view of the bonded steel pipe 50 having a cross section composed of W and _eq t is expressed by the following conditional expression (4).

Therefore, t _p , t _FB , and W (in some cases, B _C ) are designed to satisfy the following conditional expression (5). Further, the welding size and throat thickness at the time of fillet welding of the bonded steel pipe 50 and the ribs 51 and 52 are determined with respect to the bearing reaction force w.

ただし、
Ｍ_Ｃ：鋼管の平面視一辺の中央部分の曲げモーメント
ｗ：第二柱に作用するせん断力の支圧反力
Ｂ_Ｃ：鋼管の平面視一辺の内法長さ
Ｗ：支圧反力ｗの作用領域高さ
ｔ_ＦＢ：鋼管の内周面からのリブ突出長さ
_ｅｑｔ：支圧反力ｗの作用領域高さにおけるｔ_ＦＢを考慮した鋼管の等価厚さ
ｔ_Ｐ：鋼管の厚さ
_ｅｑＺ：Ｗと_ｅｑｔとで構成される断面係数
σ_Ｃ：Ｗと_ｅｑｔとで構成される断面を有する鋼管の平面視一辺の中央部分の曲げ応力度
Ｆ：鋼管を形成する鋼材のＦ値
ただし、支圧反力ｗの単位は、単位長さあたりの力（Ｎ／ｍｍ）である。

However,
M _C: viewed bending moment of the center portion of one side w of steel: the Bearing reaction forces w: Second Bearing reaction forces of shear forces acting on the pillar B _C: in plan view one side of the steel pipe inner size length W Working region height t _FB : Rib protrusion length from the inner peripheral surface of the steel pipe
_eq t: Equivalent thickness of the steel pipe in consideration of t _FB at the working region height of the bearing reaction force w t _P : Thickness of the steel pipe
_eq Z: Section modulus composed of W and _eq t σ _C : Bending stress degree at the center of one side of a steel pipe having a section composed of W and _eq t in plan view F: F of steel material forming the steel pipe Value However, the unit of the bearing pressure reaction force w is a force per unit length (N / mm).

In the joining structure of the pillars configured as described above, the main bar portion 70 of the first pillar 1 and the lower part 2A of the second pillar 2 are filled in the joining steel pipe 50 disposed on the outer peripheral side of the second pillar 2. The first pillar 1 and the second pillar 2 are joined via the stress switching part 5 by fixing to the filled concrete part 80. In addition, ribs 51 and 52 for suppressing out-of-plane buckling are provided on the upper end portion 50T and the lower end portion 50B of the bonded steel pipe 50 disposed on the outer peripheral side of the second column 2, respectively. The ribs 51 and 52 are formed so that the conditional expressions (1) to (5) are satisfied, that is, the bending stress of the central portion of one side of the bonded steel pipe 50 is equal to or less than the F value of the steel material. The protruding length t _FB from the inner peripheral surface 50N of the bonded steel pipe 50 is set. Therefore, the joining steel pipe 50 is reinforced by the ribs 51 and 52, and the out-of-plane buckling is suppressed.
Moreover, since the ribs 51 and 52 are not provided in the corner | angular part S of the joining steel pipe 50, but are provided along the plane part of the joining steel pipe 50 of planar view rectangular shape, processing of the ribs 51 and 52 is carried out. In addition, operations such as fixing to the bonded steel pipe 50 can be facilitated.

  The first concrete portion 13 of the first pillar 1, the second concrete portion 22 of the second pillar 2, and the filled concrete portion 80 in the bonded steel pipe 50 are made of fiber reinforced concrete. Therefore, cracking of the fiber reinforced concrete due to the axial force can be suppressed by the crosslinking effect of the fiber reinforced concrete. Therefore, the out-of-plane buckling of the bonded steel pipe 50 can be effectively suppressed.

  Moreover, when the stress switching part 5 is provided in the ground floor, a horizontal force acts on the joining structure of pillars at the time of an earthquake. For this reason, the length of the joining steel pipe 50 is lengthened so as to reduce the input shear force to the joining steel pipe 50, the plate thickness of the joining steel pipe 50 is increased in order to avoid the shear yield of the joining steel pipe 50, filled concrete In order to prevent the shear displacement by causing the portion 80 and the bonded steel pipe 50 to behave integrally, it is necessary to take a design measure such as providing several protrusions such as bar steels by welding or the like along the material axis direction inside the bonded steel pipe 50. . However, when the stress switching unit 5 is provided on the basement floor such as the first basement floor as in the embodiment described above, the force acting on the joint structure between the columns is more than the axial force. Therefore, it is not necessary to take the above-mentioned measures, or a gentler response than the case of providing on the ground floor is sufficient.

(Modification)
Next, a modification of the embodiment described above will be described mainly with reference to FIG.
FIG. 7: is a schematic front view which shows the junction structure of the pillars which concern on the modification of 1st embodiment of this invention.
In the following other embodiments, the same members as those used in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.
As shown in FIG. 7, a reinforced concrete first column 101 may be arranged so as to extend in the vertical direction from the floor slab F0. In this case, the column main reinforcement 11 (refer FIG. 2), the band 12 (refer FIG. 2), and the 1st concrete part 13 (refer FIG. 2) which comprise the 1st pillar 101 are provided in the area X1. In addition, the main reinforcement part 70 (refer FIG. 2) following the column main reinforcement 11 is extended to the area Z1.
The second pillar 102 is disposed over the section Y1.
The stress switching unit 105 is disposed over a section Z1 extending from the upper side of the section X1 to the lower portion of the section Y1. The second pillar 102 may be configured integrally with the third pillar 3.

In the embodiment described above, the portion extending in the vertical direction from the floor slab F0 is the stress switching portion 5, whereas in this modification, the portion extending in the vertical direction from the floor slab F0 is the first column of reinforced concrete. 101 and the stress switching part 105 joined to the first pillar 101.
The first column may be arranged so that the upper end of the first concrete portion of the first column reaches the middle of the floor slab F0 in the thickness direction, and the stress switching unit may be arranged continuously therewith. That is, the lower end of the stress switching unit may be arranged to rise from the middle of the floor slab F0 in the thickness direction.

(Second embodiment)
Next, a second embodiment will be described mainly with reference to FIGS.
FIG. 8 is a longitudinal sectional view showing the configuration of the column-to-column junction structure according to the second embodiment of the present invention. 9 is a cross-sectional view taken along the line CC of FIG.
As shown in FIG. 8, the rib 151 is provided slightly below the upper end portion 50 </ b> T of the bonded steel pipe 50. As shown in FIGS. 8 and 9, the bonded steel pipe 50 is curved at the corner S. The corner portion S is provided with a stiffening plate (stiffening portion) H1 that connects one inner peripheral surface 50N orthogonal to each other and the other inner peripheral surface 50N.

  The stiffening plates H1 are provided at the four corners S of the bonded steel pipe 50, respectively. In the present embodiment, the stiffening plate H1 is disposed so as to be inclined by about 45 ° with respect to each inner peripheral surface 50N along the horizontal plane.

  The stiffening plate H1 is formed in a plate shape, and is provided at a position above the rib 151 in the corner portion S. Both ends W1 of the stiffening plate H1 are connected to the inner peripheral surface 50N of the bonded steel pipe 50, respectively. For example, the stiffening plate H1 is formed of a steel material or the like. The stiffening plate H1 is connected from the upper end 50T side of the bonded steel pipe 50 by fillet welding or the like. The stiffening plate H1 may be configured to abut on the upper portion of the rib 151.

  In the joining structure of the columns configured as described above, the corner portion S formed by one inner circumferential surface 50N and the other inner circumferential surface 50N of the joining steel pipe 50 which are orthogonal to each other has one inner circumferential surface. A stiffening plate H1 for connecting 50N and the other inner peripheral surface 50N is provided. Therefore, since one inner peripheral surface 50N and the other inner peripheral surface 50N are connected by the stiffening plate H1, out-of-plane buckling of the corner portion S can be suppressed.

  Moreover, since the stiffening plate H1 is provided on the upper end portion 50T side of the bonded steel pipe 50 relative to the rib 151, it can be easily welded from the upper side (the upper end portion 50T side of the bonded steel pipe 50).

  If the stiffening plate H1 is in contact with the upper portion of the rib 151, the stiffening plate H1 is placed on the upper side of the rib 151 when the stiffening plate H1 is attached to the bonded steel pipe 50. It is possible to weld to fillet welding or the like without performing a groove processing such as a tip.

(Modification 1 of the second embodiment)
Next, Modification 1 of the second embodiment will be described mainly with reference to FIGS.
FIG. 10: is a longitudinal cross-sectional view which shows the joining structure of the pillars which concern on the modifications 1 and 2 of 2nd embodiment of this invention. FIG. 11 is a cross-sectional view taken along line DD of FIG. 10 in Modification 1 of the second embodiment of the present invention.
As shown in FIGS. 10 and 11, in this modification, the stiffening plate H <b> 2 is provided below the rib 51. The stiffening plate H2 is bent at a substantially right angle in plan view. The bent portion H20 of the stiffening plate H2 is disposed so as to face the corner portion S of the bonded steel pipe 50. The stiffening plates H2 are provided at two locations apart in the vertical direction.

  Both ends W2 of the stiffening plate H2 are connected to the inner peripheral surface 50N of the bonded steel pipe 50, respectively. For example, the stiffening plate H2 is formed of an L-shaped angle member or the like, and is connected by fillet welding from the opposite side of the corner portion S at both ends W2 of the stiffening plate H2.

(Modification 2 of the second embodiment)
Next, Modification 2 of the second embodiment will be described mainly using FIGS.
FIG. 12 is a DD cross-sectional view of FIG. 10 in Modification 2 of the second embodiment of the present invention.
As shown in FIGS. 10 and 12, in this modification, the stiffening plate H <b> 3 is provided below the rib 51. The stiffening plate H3 is arranged along one inner peripheral surface 50N, the corner portion S, and the inner peripheral surface 50N orthogonal to the one inner peripheral surface 50N of the bonded steel pipe 50.

  The stiffening plate H3 is welded along the inner peripheral surface 50N of the bonded steel pipe 50. For example, in the stiffening plate H3, a portion along the inner peripheral surface 50N of the bonded steel pipe 50 and both end portions W3 are connected to the inner peripheral surface 50N by fillet welding.

FIG. 13 is a diagram used for calculating the installation range W of the stiffening plates H2 and H3 having the column-to-column connection structure according to Modification 1 and Modification 2 of the second embodiment described above.
13, a (the length in the vertical direction from the position of the shearing force Q _d = 0 to the upper end 50T of the bonded steel pipe 50), h1, and h2 are represented by the following conditional expressions (6) to (8), respectively. Is done.

  As a result of the FEM analysis, the region where the bonded steel pipe 50 is deformed out of plane by the bearing reaction R1 of the shearing force acting on the second column 2 of the filled steel pipe concrete structure is about 1/3 of the height of the bonded steel pipe 50. Therefore, W shown in FIG. 10 (installation range of the stiffening plates H2 and H3 from the upper end 50T of the bonded steel pipe 50) is expressed by the following conditional expression (9).

  If it is in the installation range W shown above, the stiffening plates H2 and H3 may be installed at arbitrary positions in the vertical direction.

  It should be noted that the assembly procedure shown in the above-described embodiment, or the shapes and combinations of the constituent members are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the embodiment described above, the stiffening plates H2 and H3 are installed at two locations apart in the vertical direction, but the number is not limited to two and may be one or three or more.

  Moreover, in embodiment shown above, the case where the 1st pillar 1, the 2nd pillar 2, and the stress switching part 5 were comprised with the precast concrete member was mentioned as an example, and was demonstrated. However, this invention is not restricted to this, It is applicable also to the structure which builds the stress switching part 5 and the 2nd pillar 2 after constructing the 1st pillar 1 in a construction site. For example, fiber reinforced concrete may be filled into the filled concrete portion 80, and the inside of the second pillar 2 may be filled with normal concrete or the like. In this case, since the inside and the outside of the second pillar 2 are partitioned in the vertical direction by the base plate 23, the fiber reinforced concrete is placed on the filling concrete portion 80 (outside the second pillar 2), and Ordinary concrete can be laid inside each other.

  Moreover, the case where the 2nd pillar 2 was comprised by the filling steel pipe concrete structure was mentioned as an example, and was demonstrated. However, the present invention is not limited to this, and can also be applied to the case where the second pillar 2 is constructed of steel.

  In addition, the case where the first pillar 1 is provided on the second basement and the stress switching unit 5 and the second pillar 2 are provided on the first basement has been described as an example. However, the present invention is not limited to this, and can also be applied to the case where the first pillar 1, the stress switching unit 5, and the second pillar 2 are provided on the other floor and the ground floor.

DESCRIPTION OF SYMBOLS 1 ... 1st pillar 2 ... 2nd pillar 2A ... Lower part 5 of 2nd pillar ... Stress switching part 11 ... Column main reinforcement 13 ... First concrete part 50 ... Joined steel pipe (steel pipe)
52 ... rib 70 ... main reinforcement 80 ... filled concrete part 100 ... building S ... corner H1 ... stiffening plate (stiffening part)

Claims (4)

Columns that join a first column of reinforced concrete having a column part reinforcing bar extending vertically in the concrete part and the concrete part, and a second column of steel structure or filled steel pipe concrete structure arranged above the first column In designing the joint structure of
The first column and the second column are joined via a stress switching unit,
The stress switching part is
A lower portion of the second pillar;
A main bar portion that is disposed on the outer peripheral side of the lower portion of the second column, and that extends continuously from the concrete portion and protrudes in the vertical direction from the concrete portion;
A steel pipe having a rectangular shape in plan view, which surrounds all the main reinforcing bars and is arranged over the entire length in the vertical direction,
A filled concrete portion filled in the steel pipe,
In the upper and lower parts of the vertical direction of the steel pipe, ribs are provided in portions other than the corners so as to protrude horizontally from the inner peripheral surfaces of the steel pipe,
A method for designing a joint structure between columns, wherein the protruding length of the rib from the inner peripheral surface is set so as to satisfy the following conditional expressions (1) to (5).

However,
M _C: viewed bending moment of the center portion of one side w of steel: the Bearing reaction forces w: Second Bearing reaction forces of shear forces acting on the pillar B _C: in plan view one side of the steel pipe inner size length W Working region height t _FB : Rib protrusion length from the inner peripheral surface of the steel pipe
_eq t: Equivalent thickness of the steel pipe in consideration of t _FB at the working region height of the bearing reaction force w t _P : Thickness of the steel pipe
_eq Z: Section modulus composed of W and _eq t σ _C : Bending stress degree at the center of one side of a steel pipe having a section composed of W and _eq t in plan view F: F of steel material forming the steel pipe value Columns that join a first column of reinforced concrete having a column part reinforcing bar extending vertically in the concrete part and the concrete part, and a second column of steel structure or filled steel pipe concrete structure arranged above the first column A joining structure of
The first column and the second column are joined via a stress switching unit,
The stress switching part is
A lower portion of the second pillar;
A main bar portion that is disposed on the outer peripheral side of the lower portion of the second column, and that extends continuously from the concrete portion and protrudes in the vertical direction from the concrete portion;
A steel pipe having a rectangular shape in plan view, which surrounds all the main reinforcing bars and is arranged over the entire length in the vertical direction,
A filled concrete portion filled in the steel pipe,
In the upper and lower parts of the vertical direction of the steel pipe, ribs are provided in portions other than the corners so as to protrude horizontally from the inner peripheral surfaces of the steel pipe,
The protrusion length from the said internal peripheral surface of the said rib is set so that the following conditional expression (6)-(10) may be satisfy | filled, The joining structure of the pillars characterized by the above-mentioned.

However,
M _C: viewed bending moment of the center portion of one side w of steel: the Bearing reaction forces w: Second Bearing reaction forces of shear forces acting on the pillar B _C: in plan view one side of the steel pipe inner size length W Working region height t _FB : Rib protrusion length from the inner peripheral surface of the steel pipe
_eq t: Equivalent thickness of the steel pipe in consideration of t _FB at the working region height of the bearing reaction force w t _P : Thickness of the steel pipe
_eq Z: Section modulus composed of W and _eq t σ _C : Bending stress degree at the center of one side of a steel pipe having a section composed of W and _eq t in plan view F: F of steel material forming the steel pipe value   3. The corner portion is provided with a stiffening portion that connects the one inner peripheral surface and the other inner peripheral surface intersecting the one inner peripheral surface. Bonded structure between the listed columns. Columns that join a first column of reinforced concrete having a column part reinforcing bar extending vertically in the concrete part and the concrete part, and a second column of steel structure or filled steel pipe concrete structure arranged above the first column A joining structure of
The first column and the second column are joined via a stress switching unit,
The stress switching part is
A lower portion of the second pillar;
A main bar portion that is disposed on the outer peripheral side of the lower portion of the second column, and that extends continuously from the concrete portion and protrudes in the vertical direction from the concrete portion;
A steel pipe having a rectangular shape in plan view, which surrounds all the main reinforcing bars and is arranged over the entire length in the vertical direction,
A filled concrete portion filled in the steel pipe,
On the upper and lower parts of the steel pipe in the vertical direction, ribs are formed in portions other than the corners so as to protrude in the horizontal direction from the respective inner peripheral surfaces of the steel pipe,
The corner portion is provided with a stiffening portion that connects one inner peripheral surface and the other inner peripheral surface intersecting with the one inner peripheral surface. Construction.

Images