JP6745592B2 - CFT beam-column joint structure - Google Patents

Description

The present invention relates to a CFT column-beam joint structure for joining a CFT column in which a steel pipe is filled with concrete and a beam, and is applied to, for example, a distribution warehouse or a high-rise building.

Conventionally, a CFT column (Concrete Filled Steel Tube) has been used as a column having both the excellent tensile strength of steel and the excellent compressive strength of concrete. In the beam joint structure of the CFT column, a through diaphragm 26 is used as shown in FIGS. 11A and 11B in a longitudinal sectional view and a broken plan view (for example, Patent Document 1). This is for reliably transmitting the stress from the beam 25 to the filled concrete 23 of the CFT column 21.

When an interlayer displacement occurs in a building due to an earthquake or the like, bending and shearing force act on the beam 25, and vertical shearing force is generated at the joint portion of the CFT column 21 of the beam 25. By reliably transmitting this shearing force to the CFT columns 21, the strength of the building is secured. Therefore, at the joint between the beam 25 and the CFT column 21, transmission of shearing force is important. Therefore, the through diaphragm 26 is generally used as described above.

An opening 26a for filling concrete is provided in the center of the through diaphragm 26, and concrete 23 is filled from below the steel pipe 22 as shown by an arrow in the figure. The reason for filling from below is that filling from above may cause insufficient filling.

JP-A-11-210077

As described above, the concrete 23 of the CFT column 21 rises from the bottom to the top of the steel pipe 22 to be filled. At this time, if the through diaphragm 26 is provided, the flow of the concrete 23 is obstructed by the through diaphragm 26, and the concrete in the steel pipe 22 immediately below the through diaphragm 26 (indicated by a symbol B in FIG. 11A) is The filling property of 23 may be deteriorated or a phenomenon considered to be breathing may occur. Therefore, there is a concern that the strength of the filled concrete 23 in this portion may decrease.

In order to eliminate this concern, the mixing strength of the concrete 23 needs to be strengthened, and there is a problem that the cost increases accordingly. That is, in this case, the mixing strength mF of the concrete 23 is a value obtained by adding the strength correction value Sc to the design reference strength Fc of the concrete 23, that is, mF=Fc+Sc
And have to.
The strength correction value Sc is a value obtained by adding the structural concrete strength correction value mSn to the extra amount Sd in consideration of the strength decrease of the filled concrete 23 immediately below the through diaphragm 26, and the mixing strength mF of the concrete 23 is
mF=Fc+Sc=Fc+Sd+mSn
Becomes The intensity correction value Sc should be 10 to 15 N/mm ² if there is no experiment or reliable data.

In the conventional example using the through diaphragm 26, the steel pipe 22 is divided at a portion of the CFT column 21 where the through diaphragm 26 is interposed, the through diaphragm 26 is arranged, and then the divided steel pipe 22 is joined by welding. I have to fix it. In this respect also, the cost will increase.
Since the through diaphragm 26 also contributes to the out-of-plane rigidity of the CFT column 21, it is necessary to increase the out-of-plane rigidity of the CFT column 21 when the non-diaphragm is used.

An object of the present invention is to provide a CFT column-beam joint structure that can reliably transmit stress from the beam to the filling concrete of the CFT column without using a through diaphragm, suppress the mixing strength of the concrete, and have excellent out-of-plane rigidity. Is to provide.

The CFT column-beam joint structure of the present invention is a structure for joining a CFT column in which a steel pipe is filled with concrete and the beam, and a circumferential direction and a height at which the beam is joined to the inner surface of the steel pipe of the CFT column. Has a rib extending in the vertical direction.

According to this configuration, the ribs extending in the up-down direction are provided at the circumferential and height positions where the beams are joined on the inner surface of the steel pipe of the CFT column, and the ribs are embedded in the concrete in the steel pipe. That is, the bearing resistance is obtained on the lower edge face of the rib. Therefore, stress such as vertical shear stress and bending stress from the beam can be satisfactorily transmitted to the filled concrete in the CFT column without using a through diaphragm. Further, the ribs are integrated with the steel pipe and contribute to the improvement of the out-of-plane rigidity of the steel pipe.
In this way, the structure of a simple mechanism in which the ribs extending in the vertical direction are provided on the inner surface of the steel pipe, the conditions for both stress transmission from the beam to the CFT column and for securing the out-of-plane rigidity of the CFT column are satisfied. You can
Further, since the ribs are provided in a posture that extends in the vertical direction, they do not hinder the filling of concrete into the steel pipe, the phenomenon considered as the breathing can be avoided, and the strength of the filling concrete decreases. Never. Therefore, the mixing strength of concrete can be reduced and the cost can be reduced. That is, the stress from the beam can be reliably transmitted to the filling concrete of the CFT column without using a through diaphragm, and the mixing strength of the concrete need not be increased.

The rib is perforated steel dowels, this perforated steel dowels are shall give concrete double shear effect in each hole having this perforated steel plate dowels, the ribs in the range of RyoNaru of the beam Has a part that extends slightly up and down from.
With perforated steel plate dowels, the concrete two-sided shear effect due to each hole can be obtained, and bearing resistance can be obtained at the small edge surface at the lower end, so the stress from the beam can be more reliably transmitted to the concrete filled in the CFT column. .. Also, the out-of-plane rigidity of the CFT column is excellent due to the integration of the perforated steel plate dowel and the steel pipe.

In the present invention, the beam is H-shaped steel and has upper and lower flanges, the ribs are provided separately in the upper and lower sides, and the separated upper and lower ribs are the upper and lower flanges in the H-shaped steel beam. It may be located at each height position.
If the ribs are provided separately in the upper and lower portions, the pressure bearing resistance can be obtained at the lower edge face of each of the upper and lower ribs. Therefore, the stress transmission is excellent. When the beam is H-shaped steel, the shear stress and bending stress are transmitted from the beam to the column mainly at the height positions of the upper and lower flanges. Therefore, if the upper and lower ribs are provided at the height positions of the upper and lower flanges of the beam, the stress can be transmitted more effectively.

In the present invention, when the rib is a pressure bearing resistance rib, the rib is joined to the inner surface of the steel pipe at the base end, and a plurality of notch-shaped recesses for pressure bearing are arranged vertically at the tip of the rib. It may be formed. The “rib end” means an end opposite to the “base end”.
In the case of this configuration, since the pressure-bearing resistance area is increased by the notch-shaped recess of the pressure-bearing resistance rib, the stress from the beam can be more reliably transmitted to the filled concrete of the CFT column.

A CFT column-beam joint structure of the present invention is a CFT column-beam joint structure for joining a CFT column in which a steel pipe is filled with concrete and a beam, and a periphery of the CFT column where the beam is joined on an inner surface of the steel pipe. At the position of direction and height, there is a rib extending in the vertical direction, the rib is a perforated steel plate dowel, and this perforated steel plate dowel has a concrete two-sided shear effect in each hole that this perforated steel plate dowel has. obtained a shall, said rib can transmit order to have a portion extending slightly above and below the range of RyoNaru of the beam, the stress-filled concrete reliably CFT pillars from the beam without using through diaphragm, the concrete The effect of being able to suppress the compounding strength of and also securing the out-of-plane rigidity is obtained.

FIG. 1A is a vertical cross-sectional view of a CFT beam-column joint structure according to the first embodiment of the present invention, and FIG. (A) is a longitudinal sectional view of a CFT beam-column joint structure according to another embodiment of the present invention, and (B) is a cutaway plan view thereof. (A) is a longitudinal sectional view of a CFT beam-column joint structure according to still another embodiment of the present invention, and (B) is a cutaway plan view thereof. (A) is a longitudinal sectional view of a CFT beam-column joint structure according to still another embodiment of the present invention, and (B) is a cutaway plan view thereof. (A) is a longitudinal sectional view of a CFT beam-column joint structure according to still another embodiment of the present invention, and (B) is a cutaway plan view thereof. (A) is a longitudinal sectional view of a CFT column-beam joint structure according to a reference proposal example , and (B) is a cutaway plan view thereof. (A) is a longitudinal sectional view of a CFT beam-column joint structure according to another reference proposal example , and (B) is a cutaway plan view thereof. (A) is a longitudinal cross-sectional view of a CFT beam-column joint structure according to still another reference proposal example , and (B) is a cutaway plan view thereof. (A) is a longitudinal cross-sectional view of a CFT beam-column joint structure according to still another reference proposal example , and (B) is a cutaway plan view thereof. (A) is another reference proposal example (A) is a longitudinal sectional view of a conventional example, and (B) is a cutaway plan view thereof.

A first embodiment of the present invention will be described with reference to FIG. This CFT column-beam joint structure is a column-beam joint structure that joins a CFT column 1 and a beam 5 in which a steel pipe 2 is filled with concrete 3, and the beam 5 on the inner surface of the steel pipe 2 of the CFT column 1 is joined. Thin plate-shaped ribs extending in the up-down direction are welded at circumferential and height positions. As this rib, a perforated steel plate dowel 4 is used here.

As the steel pipe 2, a square steel pipe is used here. The beam 5 is made of H-shaped steel, and its flanges 5a are arranged in an up and down position. For each of the four inner surfaces of the steel tube 2 that is a rectangular steel tube, one perforated steel plate dowel 4 is provided at the center position of each inner surface in the width direction. The height position and the length of the perforated steel plate dowel 4 are set so as to extend slightly upward and downward from the range where the beam 5 is formed. The perforated steel plate dowel 4 does not necessarily have to be welded over its entire length, and fillet welding may be performed as long as the necessary shear strength is secured.

According to this configuration, the perforated steel plate dowel 4 which is a rib extending in the vertical direction is provided at the circumferential position and the height position where the beam 5 is joined to the inner surface of the steel pipe 2 of the CFT pillar 1. Therefore, the through-diaphragm is used because the out-of-plane rigidity of the steel pipe 2 is ensured by the effect of integrating the perforated steel plate dowel 4 with the steel pipe 2, and the bearing resistance is obtained at the lower edge of the perforated steel plate dowel 4. The stress from the beam 5 can be surely transmitted to the filled concrete 3 of the CFT column 1 without any trouble.

According to the perforated steel plate dowel 4, the concrete two-sided shearing effect by each of the holes 4a can be obtained, the out-of-plane rigidity of the steel pipe 2 can be secured more, and the bearing resistance can be also greater.
In addition, since the perforated steel plate dowel 4 is provided in a posture that extends in the vertical direction, the perforated steel plate dowel 4 does not interfere with the filling flow of the concrete 3 from the bottom to the top of the steel pipe 2 at the time of building, The strength of the concrete 3 is not lowered. Therefore, the mixing strength of the concrete 3 can be reduced and the cost can be reduced.
In this way, the stress from the beam 5 can be reliably transmitted to the filling concrete 3 of the CFT column 1 without using a through diaphragm, the mixing strength of the concrete 3 can be suppressed, and the out-of-plane at the beam joint portion of the CFT column 1 can be suppressed. Rigidity can also be secured.
The perforated steel plate dowels 4 may be provided only on the surface of the steel pipe 2 to which the beam 5 is joined. The ribs in each of the other embodiments may be provided only on the surface to which the beam 5 is joined, as in the above.

2A and 2B are a longitudinal sectional view and a cutaway plan view of another embodiment of the present invention. In this embodiment, in the CFT column-beam joint structure of the embodiment of FIG. 1, two perforated steel plate dowels 4 which are ribs are arranged side by side on each inner surface of the steel pipe 2 of the CFT column 1. Other configurations are the same as those in the previous embodiment.

In this embodiment, since two perforated steel plate dowels 4 are arranged side by side on each inner surface of the steel pipe 2 of the CFT column 1, the concrete two-sided shearing effect of the perforated steel plate dowel 4 is further enhanced, and the steel pipe 2 Larger out-of-plane rigidity can be secured. Further, since the concrete double-faced shearing effect of the perforated steel plate dowel 4 and the bearing pressure resistance at the lower edge are doubled, the stress from the beam 5 can be more reliably transmitted to the filled concrete 3 of the CFT column 1. However, since the number of perforated steel plate dowels 4 is doubled, the flow of the concrete 3 when the steel pipe 2 is filled is slightly reduced. Therefore, it is desirable to determine the number of perforated steel plate dowels 4 in accordance with the quality of the concrete 3.

3(A) and 3(B) are a longitudinal sectional view and a cutaway plan view of still another embodiment of the present invention. In this embodiment, in the CFT column-beam joint structure of the embodiment shown in FIG. 1, three perforated steel plate dowels 4 which are ribs are arranged side by side on each inner surface of the steel pipe 2 of the CFT column 1. The intervals between the perforated steel plate dowels 4 arranged side by side are the same. Other configurations are the same as those in the above embodiment.

In this embodiment, since three perforated steel plate dowels 4 are arranged side by side as ribs on each inner surface of the steel pipe 2 of the CFT column 1, the concrete two-sided shear effect of the perforated steel plate dowel 4 is shown in FIG. It is further increased as compared with the case of the embodiment, and the out-of-plane rigidity of the steel pipe 2 can be secured more. Further, since the concrete double-faced shearing effect of the perforated steel plate dowel 4 and the bearing resistance at the lower edge are further enhanced, the stress from the beam 5 can be more reliably transmitted to the filled concrete 3 of the CFT column 1. However, since the number of perforated steel plate dowels 4 is further increased, the flow of the concrete 3 when the steel pipe 2 is filled is further reduced.

4(A) and 4(B) are a longitudinal sectional view and a broken plan view of still another embodiment of the present invention. In this embodiment, in the CFT column-beam joint structure of the embodiment of FIG. 1, the steel pipe 2 of the CFT column 1 is divided into upper and lower steel pipe divided bodies 2A and 2A at a column-beam joint portion (a division line L), and the steel pipe 2 After the perforated steel plate dowel 4 which is a rib is provided on the inner surface of the above, the upper and lower steel pipe divided bodies 2A, 2A are joined by welding.

If the diameter of the steel pipe 2 is small and it is not easy to weld the perforated steel plate dowel 4 to the inner surface of the steel pipe 2, the steel pipe 2 is divided at the beam-column joints in this way, and the perforated steel plate in that state. When the joining work of the dowel 4 is performed, the joining work can be easily performed.

When joining the upper and lower steel pipe divided bodies 2A and 2A, as shown in FIG. 4A, the erection pieces 6 and 7 are joined to the upper and lower steel pipe divided bodies 2A and 2A, respectively. Attach a backing plate (not shown) and join with bolts. In this state of positioning, the upper and lower steel pipe divided bodies 2A, 2A are joined by welding. After joining, the erection pieces 6 and 7 are removed by cutting or the like. After these operations, the steel pipe 2 is filled with concrete 3. In this case, it is preferable that the perforated steel plate dowel 4 in the steel pipe 2 at the beam-column joint portion is provided so as to extend to the upper end of the steel pipe 2. Other configurations and effects are similar to those of the embodiment of FIG.

5(A) and 5(B) are a longitudinal sectional view and a cutaway plan view of still another embodiment of the present invention. In this embodiment, in the CFT column-beam joint structure of the embodiment shown in FIG. 1, two perforated steel plate dowels 4 which are ribs provided on each inner surface of the steel pipe 2 of the CFT column 1 are vertically arranged as shown in FIG. It is separated into. The upper and lower perforated steel plate dowels 4 and 4 are respectively positioned at the height positions of the upper and lower flanges 5a, 5a of the beam 5 made of H-shaped steel.

When the perforated steel plate dowels 4 are provided separately in this manner, the pressure bearing resistance is obtained at the lower edge face of the perforated steel plate dowels 4 and 4 above and below. Therefore, the stress transmission is excellent. When the beam 5 is H-shaped steel, the shear stress and the bending stress are transmitted from the beam 5 to the column 1 mainly at the height positions of the upper and lower flanges 5a and 5b. Therefore, when the upper and lower perforated steel plate dowels 4 are provided at the height positions of the upper and lower flanges 5a, 5a of the beam 5, the stress is effectively transmitted.
Even in the case where the pressure-bearing resistance ribs without holes are used instead of the perforated steel plate dowel 4, the pressure-bearing resistance ribs are provided separately in the same manner as in the example of FIG. The effect of separation can be obtained.
Other configurations and operational effects of this embodiment are similar to those of the embodiment of FIG.

6(A) and 6(B) show a longitudinal sectional view and a cutaway plan view of the reference proposal example . In this proposed example , in the CFT column-beam joint structure of the proposed example shown in FIG. 1, as a rib provided on the inner surface of the steel pipe 2 of the CFT column 1, a plate-shaped bearing resistance rib having no holes instead of the perforated steel plate dowels 4 is used. 14 is used. Also in this pressure bearing resistance rib 14, the out-of-plane rigidity of the steel pipe 2 is ensured by the effect of integration with the steel pipe 2, and the pressure bearing resistance is obtained at the lower small edge thereof, so that the beam is supported without using a through diaphragm. The stress from 5 can be reliably transmitted to the filled concrete 3 of the CFT column 1.

When the rib is the perforated steel plate dowel 4 as in the embodiment of FIG. 1, the rib 4 has a protrusion height from the inner surface of the steel pipe 2 (for example, about 100 mm) due to the presence of the hole 4a. The degree to which the filling of the concrete 3 into the interior is hindered increases. On the other hand, when the ribs are the pressure-bearing resistance ribs 14 for merely obtaining the bearing resistance, the height of protrusion from the inner surface of the steel pipe 2 may be low, so that the filling of the concrete 3 into the steel pipe 2 is accordingly performed. The degree of hindrance is reduced.

7A and 7B are a vertical sectional view and a broken plan view of another reference proposal example . In this embodiment, in the CFT column-beam joint structure of the embodiment of FIG. 6, five bearing resistance ribs 14 that are ribs are arranged side by side on each inner surface of the steel pipe 2 of the CFT column 1. The laterally-arranged pressure-bearing resistance ribs 14 have the same interval. Other configurations are the same as in the case of the proposed example of FIG.

As described above, when the rib is the pressure-bearing resistance rib 14 for merely obtaining the pressure-bearing resistance, the height of protrusion from the inner surface of the steel pipe 2 may be small, and thus the filling of the concrete 3 into the steel pipe 2 is prevented. The degree decreases. Therefore, as in this embodiment, even if the number of the pressure bearing resistance ribs 14 is increased, the filling of the concrete 3 into the steel pipe 2 is not hindered, and the out-of-plane rigidity of the steel pipe 2 is increased by the increased number. Can be made. Further, as the number of pressure bearing resistance ribs 14 increases, the total pressure bearing resistance at the lower edge increases, so that the stress from the beam 5 can be more reliably transmitted to the filled concrete 3 of the CFT column 1. However, since the degree of hindering the filling of the concrete 3 increases as the number of the pressure bearing resistance ribs 14 increases, it is desirable to determine the number of the pressure bearing resistance ribs 14 according to the quality of the concrete 3 in this case as well.

8(A) and 8(B) show a vertical cross-sectional view and a broken plan view of still another reference proposal example . In this proposed example , in the CFT column-beam joint structure of the proposed example of FIG. 6, a bearing pressure resistance rib 14 that is a rib is attached to each inner surface of the steel pipe 2 of the CFT column 1 at the base end and joined to the inner surface of the steel pipe 2, A plurality of notch-shaped recesses 14a for supporting pressure are formed side by side vertically. That is, the pressure bearing resistance rib 14 in this case has a shape in which the perforated steel plate dowel 4 used as the rib in the embodiment of FIG. Other configurations are the same as in the case of the proposed example of FIG.
As described above, when the pressure-bearing resistance rib 14 has a shape in which a plurality of notch-shaped recesses 14a for supporting pressure are vertically formed at the tip, the notch-shaped recess 14a increases the bearing-supporting area. The stress from the beam 5 can be more reliably transmitted to the filled concrete 3 of the CFT column 1. Other functions and effects are similar to those in the case of the proposed example of FIG.

9(A) and 9(B) show a longitudinal sectional view and a cutaway plan view of still another reference proposal example . In this embodiment, in the CFT column-beam joint structure of the embodiment shown in FIG. 8, five bearing resistance ribs 14 each having a notch-shaped recess 14a, which is a rib, are horizontally arranged on each inner surface of the steel pipe 2 of the CFT column 1. It is arranged. The laterally-arranged pressure-bearing resistance ribs 14 have the same interval. Other configurations are the same as in the case of the proposed example of FIG.

In this proposed example , five bearing resistance ribs 14 having notched recesses 14a are arranged side by side on each inner surface of the steel pipe 2 of the CFT column 1, so that the out-of-plane rigidity of the steel pipe 2 is further increased. Can be secured. Further, since the bearing resistance area of the bearing resistance rib 14 is further increased as compared with the embodiment of FIG. 8, the stress from the beam 5 can be more reliably transmitted to the filled concrete 3 of the CFT column 1. However, also in this case, since the flow of the concrete 3 when the steel pipe 2 is filled is reduced by increasing the number of the support resistance ribs 14, the number of the support resistance ribs 14 depends on the quality of the concrete 3 and the like. It is desirable to decide.

10(A) and 10(B) show a longitudinal sectional view and a broken plan view of still another reference proposal example . In this proposed example , in the CFT column-beam joint structure of the proposed example of FIG. 9, a reinforcing bar 15 is used in place of the bearing pressure resistance rib 14 having a notch-shaped recess 14a provided as a rib on each inner surface of the steel pipe 2 of the CFT column 1. It was what I had. Deformed bar is used for the bar 15.
As described above, even when the reinforcing bar 15 is used as the rib instead of the pressure-bearing resistance rib 14, the out-of-plane rigidity of the steel pipe 2 is ensured by the effect of being integrated with the steel pipe 2, and the pressure is supported by the lower edge of the reinforcing bar 15. Since resistance is obtained, the stress from the beam 5 can be reliably transmitted to the filled concrete 3 of the CFT column 1 without using a through diaphragm. Other configurations and operational effects are the same as those in the case of the proposed example of FIG. 9.

In each of the above-described embodiments and each reference proposal example , a case where a rectangular steel pipe is used as the steel pipe 2 of the CFT column 1 and ribs (a perforated steel plate gibber 4, a bearing resistance rib 14, a reinforcing bar 15) are provided on the inner surface thereof is used. However, the present invention is not limited to this, and after the ribs are joined to one surface of four strip-shaped steel plates, these four strip-shaped steel plates are arranged in a horizontal cross-section rectangular shape so that one side having the ribs is the inner surface. Then, the rectangular steel pipes may be formed by welding the side edges of these strip-shaped steel plates to each other. In this case, the ribs can be joined to one surface of the strip-shaped steel sheet in advance. Therefore, in order to join the ribs to the inner surface of the steel pipe 2, the middle portion in the length direction of the steel pipe 2 is divided, and after joining the ribs is completed. The work of rejoining the divided parts by welding is unnecessary.

Although the embodiments for carrying out the present invention have been described above based on the embodiments, the embodiments disclosed herein are illustrative and non-restrictive in all respects. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

1...CFT column 2...Steel pipe 3...Concrete 4...Perforated steel plate dowel (rib)
5... Beam 14... Bearing resistance rib 14a: Notch-shaped recess 15... Reinforcing bar (rib)

Claims (3)

A CFT column-beam joining structure for joining a CFT column and a beam filled with concrete in a steel pipe, wherein a vertical direction is provided at a circumferential direction and a height position where the beam is joined on an inner surface of the steel pipe of the CFT column. has a rib extending, said ribs are perforated steel dowels, this perforated steel dowels are shall give concrete double shear effect in each hole having this perforated steel plate dowels, the ribs the A CFT column-beam joint structure having a portion slightly extending vertically from the range of beam formation. The CFT beam-column joint structure according to claim 1, wherein the rib is joined to an inner surface of the steel pipe at a base end thereof, and a plurality of notch-shaped recesses for supporting pressure are formed vertically at a tip end of the rib. CFT beam-column joint structure. The CFT column-beam joint structure according to claim 1 or 2, wherein the beam is H-shaped steel, has upper and lower flanges, and the ribs are provided separately in the upper and lower parts, and the separated upper and lower parts are provided. The CFT column-beam joint structure in which the ribs are respectively located at the height positions of the upper and lower flanges of the H-shaped steel beam.

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