A building structure with capitals that embed multiple beam-post connections

Abstract

To provide a building structure having a capital in which multiple column-beam connection parts capable of suppressing the occurrence of punching destruction are buried even when a column core of a column of a lower layer is displaced from a column core of each column of a column-beam frame of an upper layer.SOLUTION: In a building structure, a capital 7 in which multiple column-beam connection parts 8 of a column-beam frame 1 of an upper layer are embedded on a lower layer column 2 so as to be displaced from a column core 2C part of the lower layer column is supported, a pair of upper and lower plate-like diaphragms 10 for joining a CFT column and a first steel beam are provided on each column-beam connection part for connecting the CFT column 8 and the first steel beam 4 of the column-beam frame so as to protrude around the CFT column, and out of a plate thickness dimension and a width dimension of the diaphragm for regulating a cross-sectional area of the diaphragm, the width dimension is formed larger than a width dimension of the first steel beam so as to expand a punching destruction region P of the capital by a column axial force F of each CFT column along a plate surface of the diaphragm to support the column axial force by the diaphragm.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a building structure having a capital with multiple embedded column-beam joints that can suppress the occurrence of punching failure even when the column center lines of columns in a lower story are misaligned relative to the column center lines of each column of the column-beam structure in an upper story. [Background technology]

[0002] Patent Documents 1 to 3 are known as building structures in which the vertical column axial force of a column-beam frame on an upper story is supported by columns on a lower story that are fewer in number than the points of application of the column axial force.

[0003] The "multiple-building connected building" in Patent Document 1 is a building in which several adjacent buildings are connected to each other, with multiple columns in each building being integrated with each other at their lower ends and with seismic isolation devices interposed between the lower ends of the integrated columns, and the support positions of the seismic isolation devices for the lower ends of the columns are located on the outer periphery of the building relative to the center of gravity of each building.

[0004] In the "Seismic isolation structure and construction method of the seismic isolation structure" of Patent Document 2, the seismic isolation structure does not have seismic isolation devices under the upper columns at both ends in the left-right direction in the drawing of the upper second structural face, where the fluctuating axial force during an earthquake is large, but the column axial force of the upper columns is mainly concentrated in the upper columns and is borne by the seismic isolation devices. As a result, the long-term load acting on the seismic isolation devices is made larger than the fluctuating axial force during an earthquake.

[0005] The "seismic isolated building" of Patent Document 3 is a seismically isolated building having a lower structure and an upper structure connected via a seismic isolation device, in which at least one protruding corner forming the upper structure is constructed of a wall or exterior material, and the upper column adjacent to the protruding corner is supported by a protruding corner inclined column arranged so that its lower side expands outward and is connected to the lower structure. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2001-295494 A [Patent Document 2] JP 2017-160608 A [Patent Document 3] JP 2019-082092 A Summary of the Invention [Problem to be solved by the invention]

[0007] In this type of building structure, the number of columns on the lower floors is fewer than the multiple columns of the column-beam frame on the upper floors, so the center lines of the columns on the lower floors may be misaligned relative to the center lines of the columns on the upper floors.

[0008] If the column center positions of the columns on the upper and lower floors are shifted from each other, there is a problem that the vertical axial force of each column on the upper floor makes it easier for punching destruction to occur around the columns on the lower floor, and measures to suppress punching destruction were desired.

[0009] The present invention was devised in consideration of the above-mentioned conventional problems, and aims to provide a building structure having a capital with multiple embedded column-beam joints that can suppress the occurrence of punching failure even when the column center lines of the columns in the lower story are misaligned with respect to the column center lines of each column of the column-beam structure in the upper story. [Means for solving the problem]

[0010] The building structure having a capital with multiple column-beam joints embedded therein according to the present invention is a building structure in which a capital is supported on a lower column, in which multiple adjacent column-beam joints of an upper-level column-beam structure are embedded in the lower column by shifting their positions from the column center of the lower column, and each of the column-beam joints connecting the columns and beams of the upper-level column-beam structure is provided with a pair of upper and lower plate-shaped diaphragms that protrude around the column to join the column and the beam, and the width dimension of the diaphragm in the vertical direction and the width dimension in the beam width direction that define the cross-sectional area of ​​the diaphragm that imparts shear resistance to the diaphragm are formed larger than the width dimension of the beam so that the punching destruction area of ​​the capital due to the column axial force of each of the columns is expanded along the plate surface of the diaphragm, allowing the diaphragm to support the column axial force.

[0011] The pair of upper and lower diaphragms are formed with a strength sufficient to transmit a column axial force to the capital and the beam.

[0012] The capital and the beam around the column-beam joint are characterized in that they are formed with a strength sufficient to bear a predetermined column axial force.

[0013] The lower diaphragm is characterized in that the punching destruction region is formed from the lower surface of the lower diaphragm to the lower surface of the capital.

[0014] The upper diaphragm is characterized in that the punching destruction region is formed from the lower surface of the upper diaphragm to the lower surface of the lower diaphragm. Effect of the Invention

[0015] In a building structure having a capital with multiple column-beam joints embedded according to the present invention, the occurrence of punching failure can be suppressed even when the column center lines of the columns in the lower story are misaligned relative to the column center lines of each column in the column-beam structure of the upper story. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is an enlarged side view of a main portion showing a preferred embodiment of a building structure having a capital with multiple column-beam joints embedded therein according to the present invention. [Diagram 2] 2 is a view taken along line AA in FIG. [Diagram 3] 2 is a plan view of a column-beam joint to explain a diaphragm used in a building structure having a capital in which multiple column-beam joints shown in FIG. 1 are embedded. FIG. [Figure 4] FIG. 4 is a side view of the diaphragm shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A preferred embodiment of a building structure having a capital with multiple embedded beam-column connections according to the present invention will be described in detail below with reference to the accompanying drawings. Fig. 1 is an enlarged side view of a main part of the building structure according to this embodiment, and Fig. 2 is a view taken along line AA in Fig. 1.

[0018] The building structure having a capital with multiple column-beam joints embedded in it in this embodiment is constructed by supporting an upper-story column-beam structure 1 (hereinafter sometimes simply referred to as the column-beam structure) on a lower-story reinforced concrete column 2 (hereinafter sometimes simply referred to as the lower-story column).

[0019] The column-beam frame 1 is a mixed structure in which the columns are concrete-filled steel pipe columns 3 (hereinafter referred to as CFT columns) and the beams are H-shaped steel beams 4, 5. In the illustrated example, the CFT columns 3 have a square cross section, but they may also have a circular cross section or the like.

[0020] The columns of the column-beam structure 1 may be made of steel concrete, steel reinforced concrete, or steel other than the CFT columns 3, and the beams of the column-beam structure 1 may be made of steel reinforced concrete. The lower level columns 2 may be made of steel reinforced concrete.

[0021] A seismic isolation member 6 such as laminated rubber is placed on top of the lower column 2, aligned with the column center position 2C of the lower column 2, and a capital 7 made of reinforced concrete that forms the upper part of the lower column 2 is placed on top of this seismic isolation member 6, and the capital 7 is supported by the lower column 2.

[0022] The center of gravity of the capital 7 supporting the column-beam structure 1 roughly coincides with the column core position 2C of the lower column 2.

[0023] A plurality of adjacent column-beam connections 8 of the column-beam structure 1 are embedded in the capital 7. As is well known, the column-beam connection 8 refers to a portion that joins a column and a beam, and in this embodiment, it refers to a portion that joins a CFT column 3 and a steel beam 4 (a first steel beam described later) that constitute the column-beam structure 1.

[0024] Since the column-beam structure 1 is supported by the lower columns 2 below the capital 7, the part that constitutes the lowest part of the column-beam structure 1, specifically, the lower end of the CFT column 3 that is located at the lowest part of the column-beam structure 1 and constitutes the column-beam joint 8, as well as parts of the periphery of the column-beam joint 8 of the steel beams 4, 5 arranged at the lowest part of the column-beam structure 1, are embedded in the capital 7.

[0025] In the building structure of this embodiment, the vertical column axial force F of the column-beam structure 1 is supported by lower columns 2 whose number is fewer than the points of application of the column axial force F, i.e., the column-beam structure 1 is supported by lower columns 2 whose number is fewer than the multiple CFT columns 3 of the column-beam structure 1.

[0026] In this embodiment, a plurality of CFT columns 3 of the column-beam frame 1 are provided on the capital 7 on one lower column 2.

[0027] Multiple CFT columns 3 are embedded in the capital 7 with their positions offset from one lower column 2 .

[0028] The illustrated example shows a case in which two CFT columns 3, a first steel beam 4 extending in the direction in which the two CFT columns 3 are lined up and connecting the two CFT columns 3, two adjacent column-beam joints 8 joining the first steel beam 4 and the CFT column 3, and a second steel beam 5 joined perpendicularly to the first steel beam 4 at the center position of the two CFT columns 3 are embedded in the capital 7.

[0029] In addition, in the illustrated example, the first and second steel beams 4, 5, which are partially embedded in the capital 7, are embedded in concrete together with reinforcing bars 9 to form a structure continuous with the reinforced concrete capital 7, thereby forming beams of steel reinforced concrete construction.

[0030] The number of CFT columns 3 to be installed in the capital 7, and therefore the number of column-beam joints 8, are not limited to the example shown in the figure as long as there are multiple them, and the number of first steel beams 4 and the presence or absence and number of second steel beams 5 are also not limited to the example shown in the figure.

[0031] The structure of the column-beam joint 8 itself, which connects the CFT column 3 of the column-beam frame 1 to the first steel beam 4, is conventionally known, and is configured by providing a pair of upper and lower plate-like diaphragms 10 that join a pair of upper and lower flanges 4a of the first steel beam 4 to the CFT column 3. These diaphragms 10 are formed in a quadrangular shape in plan, preferably a square shape in plan.

[0032] The diaphragm 10 used in the building structure of this embodiment is provided to protrude around the CFT column 3. Specifically, an external diaphragm or a through diaphragm having a through hole is used.

[0033] In the case of an external diaphragm, it is welded to two points, top and bottom, on the outer surface of the CFT column 3 that penetrates the column-beam connection section 8.

[0034] On the other hand, in the case of a through diaphragm, the end faces of the CFT column 3 are welded from above and below to a pair of upper and lower through diaphragms that penetrate the column-beam connection section 8, and a pipe material of the same diameter as the CFT column 3 is provided between the upper and lower through diaphragms, and concrete is filled in through the through hole.

[0035] As shown in Figure 1, in order to support a column-beam structure 1 with fewer lower columns 2 than the multiple CFT columns 3 of the column-beam structure 1, if the column center 8C of the CFT column 3 embedded in the capital 7 is shifted relative to the column center 2C of the lower column 2, then due to this structure, punching failure is likely to occur in the capital 7 around the lower column 2 due to the vertical column axial force F acting from the CFT column 3, regardless of whether it is a short-term load or a long-term load.

[0036] In capital 7 in which diaphragm 10 is embedded in column-beam joint 8 of column-beam structure 1, punching failure causes cracks in the concrete downward from diaphragm 10, with the truncated cone-shaped cone surface acting as the interface (indicated by P in the figure), regardless of whether it is the upper or lower diaphragm 10.

[0037] The vertical column axial force F of the CFT column 3 of the column-beam structure 1, which causes punching failure, acts on the first steel beam 4 and diaphragm 10 that constitute the column-beam connection section 8, and therefore the vertical shear strength of these first steel beam 4 and diaphragm 10, specifically the shear strength of the web 4b of the first steel beam 4 and the shear strength in the plate thickness direction of each of the upper and lower plate-shaped diaphragms 10, is relevant.

[0038] The shear resistance of the first steel beam 4 is determined by the shear strength of the steel material and the cross-sectional area of ​​the web 4b. The shear resistance in the plate thickness direction of each of the upper and lower diaphragms 10 must be greater than the value obtained by subtracting the shear resistance of the first steel beam 4 from the vertical column axial force F acting from the CFT column 3.

[0039] The shear strength of diaphragm 10 in the thickness direction is set to the smallest value of three values: the bending strength of diaphragm 10, the bearing strength of the concrete below diaphragm 10 (upper diaphragm 10U and lower diaphragm 10L), and the shear strength of the concrete in the punching failure area P described below.

[0040] The bending strength of the diaphragm 10 is calculated from the section modulus of the diaphragm 10 in the thickness direction and the bending moment acting on the part protruding from the CFT column 3 to the periphery. The bearing strength of the concrete below the diaphragm 10 is calculated from the total area of ​​the range where the upper and lower diaphragms 10 and the concrete contact each other (for the upper diaphragm 10U, the area of ​​the part protruding from the CFT column 3 to the periphery, and for the lower diaphragm 10L, the total area facing downward) and the concrete strength.

[0041] Compared to these strengths, the shear strength of the concrete in the punching failure region P in commonly used diaphragms 10 is small, and the shear strength of the diaphragm 10 in the thickness direction is usually determined by the shear strength of the concrete in the punching failure region P.

[0042] Normally, the width dimension of the diaphragm 10, for example a through diaphragm, is a size that protrudes about 25 to 30 mm from the outer circumference of the column. In this embodiment, as shown in Figures 3 and 4, for all diaphragms 10 of each column-beam connection section 8, the vertical plate thickness dimension T of the diaphragm 10 and the width dimension W of the diaphragm 10 in the beam width direction (flange width direction of the first steel beam 4), which determine the cross-sectional area of ​​the diaphragm 10 that imparts shear strength to the diaphragm 10, are formed larger than the width dimension BW (width dimension of the flange) of the first steel beam 4 so that the punching destruction area of ​​the capital 7 due to the vertical column axial force F of each CFT column 3 (the area inside the cone surface of the truncated truncated cone surrounded by the interface P in the figure) is expanded along the plate surface of these diaphragms 10, allowing these diaphragms 10 to support the column axial force F.

[0043] The expansion of the punching destruction area means that the diameter of the truncated cone shape is greatly expanded. In the strength analysis, the interface P of the cone surface can be expanded in any manner, but generally, it is expanded from the outer periphery of the diaphragm 10 in a direction of 45° outward and downward with respect to the horizontal plane. The punching destruction region can be made wider by increasing the width dimension of the diaphragm 10, which has a square planar shape, than when the width dimension of the diaphragm 10 is narrow.

[0044] Furthermore, each of the diaphragms 10 above and below the column-beam connection portion 8 is formed with a strength sufficient to transmit the column axial force F to the capital 7 and the first steel beam 4.

[0045] In addition, the capital 7 and the first steel beam 4 around the column-beam joint 8 are formed with a strength capable of bearing a predetermined column axial force F that does not lead to punching failure.

[0046] Of the pair of upper and lower diaphragms 10, the lower diaphragm 10L forms a punching destruction area from the underside of the lower diaphragm 10L to the underside of the capital 7, and the width dimension W of the lower diaphragm 10L is set based on the shear strength of the capital 7 with respect to this punching destruction area.

[0047] Of the pair of upper and lower diaphragms 10, the upper diaphragm 10U may be formed to have a smaller plate thickness dimension T than the lower diaphragm 10L, or may be formed to have a smaller width dimension W than the lower diaphragm 10L.

[0048] In the building structure having a capital with multiple embedded column-beam connections according to the present embodiment described above, for each column-beam connection 8, a pair of plate-like diaphragms 10 are provided in an upper and lower direction protruding around the CFT column 3. The plate thickness dimension T in the vertical direction of the diaphragm 10 and the width dimension W in the beam width direction, which give the diaphragm 10 a shear strength, are set so that the punching destruction area P of the capital 7 due to the column axial force F of each CFT column 3 is expanded along the plate surface of the diaphragm 10, and the diaphragm 10 supports the column axial force F. Since it is formed larger than the width dimension BW, even if the column center of the lower column 2 is misaligned with the column center of each CFT column 3 of the column-beam structure 1, the column axial force F can be appropriately and sufficiently borne by the shear strength of the diaphragm 10 and the shear strength of the first steel beam 4 connected to the diaphragm 10. Furthermore, the transmission performance of the column axial force F from the diaphragm 10 to the capital 7 can be improved, and in addition, the resistance action can be increased by expanding the punching failure area in the capital 7, so that the occurrence of punching failure can be effectively suppressed. [Explanation of symbols]

[0049] 1 Column beam frame 2 Lower pillar 2C Center of lower column 3 CFT pillar 4. First steel beam 7. Capital 8 Column and beam joint section 10 Diaphragm 10U Upper Diaphragm 10L Lower diaphragm BW Width dimension of the first steel beam F Vertical column axial force P: Interface of punching fracture area T Diaphragm thickness in the vertical direction W Diaphragm width in beam width direction

Claims

1. A building structure in which a capital is supported on a lower-level column by displacing adjacent column-beam joints of an upper-level column-beam frame from the center of the lower-level column, At each of the column-beam joints connecting the columns and beams of the column-beam frame of the upper floor, a pair of plate-shaped diaphragms for joining the columns and the beams are provided at the top and bottom, protruding around the columns, A building structure having a capital with multiple column-beam joints embedded therein, characterized in that the width dimension of the diaphragm in the vertical direction and the width dimension in the beam width direction, which define the cross-sectional area of ​​the diaphragm that imparts shear strength to the diaphragm, are formed larger than the width dimension of the beam so that the punching destruction area of ​​the capital due to the column axial force of each of the columns is expanded along the plate surface of the diaphragm, allowing the diaphragm to support the column axial force.

2. 2. A building structure having a capital with multiple column-beam joints embedded therein, as described in claim 1, wherein the pair of upper and lower diaphragms are formed with a strength sufficient to transmit column axial force to the capital and the beam.

3. A building structure having a capital with multiple column-beam joints embedded therein, as described in claim 1 or 2, characterized in that the capital and the beam around the column-beam joint are formed with a strength sufficient to withstand a predetermined column axial force.

4. A building structure having a capital in which a plurality of column-beam joint sections are embedded, as described in any one of claims 1 to 3, characterized in that the lower diaphragm forms the punching destruction area from the lower surface of the lower diaphragm to the lower surface of the capital.

5. A building structure having a capital in which a plurality of column-beam joint sections are embedded, as described in any one of claims 1 to 4, characterized in that the upper diaphragm forms the punching destruction area from the underside of the upper diaphragm to the underside of the lower diaphragm.

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