JP2019138137A - Junction structure of cft column and rc column - Google Patents

Abstract

An object of the present invention is to provide a joint structure of a CFT column and an RC column that can reduce the amount of steel material used and reduce the amount of on-site work. A structure A for joining a lower CFT column 2 and an upper RC column 3 is formed at the upper end of the CFT column 2 with a steel pipe 5 extending upward. A neck wrapping steel pipe portion 6 having a stiffening portion 9 protruding inward from the inner surface is provided, a main reinforcement 7 of the RC column 3 is inserted into the neck wrapping steel pipe portion 6, and concrete 8 is placed inside the neck wrapping steel pipe portion 6. Constructed by pouring and filling. [Selection drawing] Fig. 3

Description

  The present invention relates to a joint structure of a CFT column and an RC column.

  For example, in a multi-level logistics facility, a floor having a floor height of more than 10 m is provided on a lower floor, and a warehouse facility is constructed by providing a multi-layered and complicated material handling rack in the floor and has been put to practical use.

  On the other hand, it is practically difficult to plan a high-rise RC column with a floor height exceeding 10 m due to technical difficulties such as the concrete placement method and the weight of PC. It is also difficult to apply due to technical difficulties such as complicated steel frame construction for material handling bases, advancement of material handling timing, and demand for shortening the construction period of higher floors due to securing the process.

  On the other hand, the above-mentioned problems are solved by configuring the lower floors of the higher floors with CFT columns and joining the CFT columns (concrete-filled steel pipe columns) of the lower floors with the RC columns (reinforced concrete columns) of the upper floors. Can be.

  Further, as a structure / construction method for joining the RC column and the CFT column, there is a method in which switching from the CFT column to the RC column is performed in units of layers (see, for example, Patent Document 1).

  In this structure / construction method, a boundary layer is formed between a lower layer portion having a CFT column and an upper layer portion having an RC column, and extends between the upper and lower beams in this boundary layer, which is a joint portion between the CFT column and the RC column. A steel pipe is provided. The steel pipe is filled with concrete, and column main bars extending from the RC column in the upper layer are inserted. Further, strip bars surrounding the plurality of column main bars are arranged at the column heads of the columns in the boundary layer. A stud is protruded on the inner peripheral surface of the steel pipe in a portion below the column head of the boundary layer column.

  As another structure / construction method for joining the CFT column to the RC column, a base plate is provided at the lower end of the steel pipe of the CFT column, the base plate is placed on the upper end surface of the concrete portion of the RC column, the CFT column is erected, and the RC column There are some which fix the base plate to the concrete part through anchor bolts fixed in the concrete part.

JP 2009-2006 JP

  However, in the conventional structure / construction method in which the steel pipe is arranged in the boundary layer, the entire column of the boundary layer, that is, the switching from the CFT column to the RC column in units of layers is performed, so that the amount of steel used is very large. There's a problem.

  Further, in the structure / construction method in which the conventional base plate is placed on the upper end surface of the concrete portion of the RC column and the CFT column is erected, the anchor bolt is disposed at a predetermined position before placing the concrete portion of the RC column. It is necessary to fasten the base plate and the anchor bolt with a nut or the like, and there is a problem that field work is complicated and requires a lot of labor and time.

  An object of this invention is to provide the joining structure of the CFT pillar and RC pillar which can reduce the amount of steel materials to be used, and can reduce field work in view of the said situation.

  In order to achieve the above object, the present invention provides the following means.

  The joining structure of the CFT pillar and RC pillar of the present invention is a structure for joining the lower CFT pillar and the upper RC pillar, and has a shape in which a steel pipe is extended upward at the upper end of the CFT pillar. A root winding steel pipe portion formed in the above is provided, and the main reinforcement of the RC column is inserted into the inside of the root winding steel pipe portion, and concrete is cast and filled inside the root winding steel pipe portion. And

  In the joint structure of the CFT column and the RC column of the present invention, the amount of steel used can be reduced and the work on site can be reduced as compared with the conventional structure, and the workability and economical efficiency of joining the CFT column and the RC column can be reduced. Can be greatly improved.

It is a figure which shows the multilayer logistics facility provided with the junction structure of the CFT pillar and RC pillar which concern on one Embodiment of this invention. It is a figure which shows the junction structure of the CFT pillar and RC pillar which concern on one Embodiment of this invention. It is a figure which shows the junction structure of the CFT pillar and RC pillar which concern on one Embodiment of this invention. It is a figure which shows the moment share of the junction structure (joint part) of the CFT pillar and RC pillar which concern on one Embodiment of this invention, and the stress for a design. It is a figure which shows the construction method using the junction structure (joint part) of the CFT pillar and RC pillar which concerns on one Embodiment of this invention. It is a figure which shows the junction structure of the CFT pillar and RC pillar which concern on the modification of one Embodiment of this invention. Specimen No. used in the structural performance confirmation experiment 1A is an elevational view showing the configuration of FIG. 1, FIG. 7B is a cross-sectional view taken along the line AA ′ of FIG. 7A, and FIG. is there. It is a figure which shows the force cycle performed in structural performance confirmation experiment. Specimen No. It is a figure which shows 1 CFT column base part bending moment-member deformation angle relationship (a shear force-member deformation angle relationship is also written together). Specimen No. FIG. 2 is a diagram showing a CFT column base part bending moment-member deformation angle relationship (a shear force-member deformation angle relationship is also shown). Specimen No. FIG. 3 is a diagram illustrating a CFT column base part bending moment-member deformation angle relationship (a shear force-member deformation angle relationship is also shown). Specimen No. FIG. 4 is a diagram showing a CFT column base part bending moment-member deformation angle relationship (a shear force-member deformation angle relationship is also shown). Specimen No. FIG. 5 is a diagram illustrating a CFT column base part bending moment-member deformation angle relationship of 5 (shear force-member deformation angle relationship is also shown). Specimen No. FIG. 6 is a diagram showing a CFT column base bending moment-member deformation angle relationship of 6 (shear force-member deformation angle relationship is also shown). Specimen No. 1 is a photograph showing a destruction state in No. 1, showing (a) when R = + 1.0%, and (b) when + 5.0% (final destruction).

  Hereinafter, with reference to FIG. 1 to FIG. 5, a joint structure of a CFT column and an RC column according to an embodiment of the present invention will be described.

First, in the present embodiment, for example, as illustrated in FIG. 1, the description will be made on the assumption that the joint structure A of the CFT column and the RC column of the present invention is applied to the frame of the warehouse 1 of the multi-layer logistics facility.
In addition, the warehouse 1 is configured, for example, by providing a floor having a floor height of more than 10 m on a lower floor, and having a multi-layered and complicated material handling rack. Further, the lower floor portion 1a of the higher floor height is configured as a CFT structure including the CFT pillar 2, and the upper layer portion 1b is configured as an RCSS structure including a hybrid frame in which the RC pillar 3 and the steel beam 4 are combined.

  The joint structure A of the CFT column and the RC column of the present invention is not only applied to the multi-layer logistics facility (1), but, for example, the lower layer part (the lower layer part 1a) of the CFT structure can be used in an office, a commercial facility, an RCSS structure, The high-rise part (upper part 1b) of the RC structure may be adopted in a facility that is a complex facility having a house / hotel. If the lower part 1a is provided with the CFT pillar 2 and the upper part 1b is provided with the RC pillar 3 It is not necessary to limit the application target.

  On the other hand, as shown in FIGS. 2 and 3, the joint structure A between the CFT column and the RC column of the present embodiment is such that the steel pipe 5 of the CFT column 2 of the lower layer portion 1 a extends from the top portion 2 a of the CFT column 2 to the root winding level ( About 1.5 m) The steel bar 5 extends upward, and the main reinforcement 7 of the RC column 3 of the upper layer 1b is inserted into the inside of the root winding steel pipe part 6 and the concrete 8 is cast and filled. To be fixed.

  Further, an annular rib plate that protrudes inward from the inner surface of the root winding steel pipe portion 6 and extends in the circumferential direction is connected to the top portion 6a side of the neck winding steel pipe portion 6 as a stiffening portion 9, and the rib winding plate is used to form the root winding steel pipe. The portion 6 is stiffened to suppress out-of-plane deformation. Further, as shown in FIG. 3, a fixing plate 10 is attached to the lower end portion 7 d of the main reinforcement 7 of the RC pillar 3 at the portion inserted into the root winding steel pipe portion 6. Thereby, since the main reinforcement 7 and the concrete 8 inside the root winding steel pipe part 6 are integrated, the main reinforcement 7 is prevented from coming out of the concrete 8 inside the root winding steel pipe part 6 as the deformation gradually increases, and the root winding steel pipe. The shear strength of the concrete 8 inside the portion 6 is reliably ensured.

  Furthermore, the joint structure A between the CFT column and the RC column of the present embodiment is configured to satisfy the following conditions regarding stress transmission.

  First, as shown in FIG. 3 and FIG. 4, the bending moment sharing elements are the RC column portion from the height of the inflection point of the RC column 3 to the switching height of the top portion 6 a of the root winding steel pipe portion 6, and the switching height. To the upper end of the beam 4 directly below the CFT column 2 and a second lever part from the stiffening part 9 by the rib plate to the bottom part 6b of the root steel pipe part 6.

  Then, as shown in FIG. 4 and Table 1, design stress for each element is set. Note that the axial force is transmitted only in the reinforced concrete portion, and the axial force is not borne by the steel pipe 6 in the lever portion.

  Further, the bending stress and the additional shearing force of the lever portion are set as shown in FIG. 4 and equations (1) to (5).

  Here, a is the distance from the switching height to the inflection point height, M1 is the bending moment at the height of the bottom 6b of the root winding steel pipe part 6, Q is the shearing force at the inflection point height position, and h1 is the switching height. The distance from the stiffening portion 9 to the stiffening portion 9, he is the distance from the root winding steel pipe portion 6 to the switching height, h 2 is from the bottom 6 b of the root winding steel pipe portion 6 to the upper end of the beam 4 directly below the CFT column 2. The distance, h0 is the distance from the upper end of the beam 4 directly below the CFT column 2 to the stiffening portion 9, R1 is the shear force at the height of the stiffening portion, and R2 is the beam directly below the CFT column 2 4 is the shearing force at the upper end height position.

In addition, as for the joining structure A of the CFT pillar and RC pillar of this embodiment, it is desirable to set the application range as shown in Table 2 below.
a) Applies to buildings with a height of 60m or less.
b) Not applicable to columns where pulling force is generated during an earthquake.
c) Use square cross-section members for RC and CFT columns.
d) The RC column and the CFT column are aligned, and no eccentricity is allowed.
e) Do not attach the brace directly to the joint column.
f) The material standards, shapes, dimensions, plate thicknesses, etc. of bonding materials and materials to be bonded are based on Table 1.
g) Yield hinges at the main joint and joint leg are not allowed.

  Next, an example of a method for joining the CFT pillar 2 of the lower layer portion 1a and the RC pillar 3 of the upper layer portion 1b using the joint structure A of the CFT pillar and the RC pillar of the present embodiment will be described.

  First, as shown in FIG. 5 (a), the steel pipe 5 of the CFT column 2 provided integrally with the rib plate (stiffening part 9) and the root winding steel pipe part 6 is welded to the top part 2a. Include.

  As shown in FIGS. 5 (b) and 5 (c), the steel beam 5 is joined to the steel pipe 5 of the CFT pillar 2 by bolting the end, and the deck plate 11 is laid while being supported by the steel beam 4. The slab muscle 12 is arranged.

  Next, as shown in FIGS. 5 (d) and 5 (e), concrete 8 is cast and filled in the steel pipe 5 of the CFT pillar 2 excluding the root winding steel pipe portion 6, and slab concrete 13 is cast. To do.

  As shown in FIG. 5 (f), the reinforcing bar unit 16 of the RC pillar 3 with the donut spacers 14 attached to the upper and lower predetermined positions and the guide angles 15 at the four corners is lifted by a lifting machine, and the lower end side of the root pipe steel pipe part 6 is lifted. Insert the rebar unit 16 by inserting it inside. Moreover, as shown in FIG.5 (g), installing the formwork 17 of RC pillar 3 above the root winding steel pipe part 6, supporting it with a support.

  Next, as shown in FIG. 5 (h), the concrete 8 of the RC pillar 3 is placed and the concrete 8 is placed inside the root winding steel pipe portion 6. By removing the formwork 17 when the concrete 8 develops a predetermined strength, the CFT column 2 and the RC column 3 are integrally connected by the joint structure A of the CFT column and the RC column of the present embodiment.

  Therefore, in the joint structure A of the CFT column and the RC column of the present embodiment configured as described above, the amount of steel used can be reduced and field work can be reduced compared to the conventional structure, and the CFT column 2 and the RC column can be reduced. It is possible to greatly improve the workability and economical efficiency for joining the columns 3.

  In the joint structure A of the CFT pillar and the RC pillar of the present embodiment, it is configured so as to satisfy the conditions of the above formulas (1) to (5). High joints can be realized.

  Furthermore, in the present embodiment, it is possible to reduce the body cost (the number of steel frames) by an amount corresponding to the area set in the RCSS construction method. In addition, since the construction can be performed in advance with only the higher floors of the CFT structure, the material handling period of the lower layer area can be secured.

  Further, since the fixing plate 10 is attached to the lower end portion 7d of the main reinforcement 7 of the RC column 3, the main reinforcement 7 is prevented from coming out of the concrete 8 inside the root winding steel pipe section 6 due to the gradual increase of deformation, and the root winding. The shear strength of the concrete 8 inside the steel pipe part 6 is reliably ensured.

(Modification)
Next, a modification of the embodiment described above will be described mainly with reference to FIG.
In the following modifications, the same members as those used in the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted.
As shown in FIG. 6, in this modification, a reinforcing bar (a main bar different from the main bar 7) 18 is provided. The reinforcing bar 18 extends in the vertical direction. The reinforcing bar 18 is disposed across the boundary portion P between the root winding steel pipe portion 6 and the RC column 3.

  The lower part of the reinforcing bar 18 is arranged inside the root winding steel pipe part 6. The lower end 18 d of the reinforcing bar 18 is disposed above the lower end 7 d of the main bar 7. A fixing plate 19 is attached to the lower end 18 d of the reinforcing bar 18. The fixing plate 19 integrates the main reinforcement 7 and the concrete 8. The fixing position of the reinforcing bar 18 may be up to the height position of the lower end portion 7d of the main bar 7.

  The upper part of the reinforcing bar 18 is arranged inside the RC pillar 3. The upper end 18u of the reinforcing bar 18 is disposed below the upper end (not shown) of the main bar 7.

  The length from the boundary portion P to the lower end portion 18d of the reinforcing bar 18 and the length from the boundary portion P to the upper end portion 18u of the reinforcing bar 18 are set according to the concrete strength and the reinforcing bar strength. About 50 times.

  In this modification, the rib plate (stiffening portion 9) shown in the above embodiment is not provided.

  In the joint structure A1 between the CFT column and the RC column shown above, the amount of steel used can be reduced and the work at the site can be reduced compared to the conventional structure, and the construction of joining the CFT column 2 and the RC column 3 can be performed. And economic efficiency can be greatly improved.

Next, the structural performance confirmation experiment result of the joint structure A of the CFT column and the RC column of the embodiment described above will be described.
In this experiment, the CFT column and RC column are switched to the RC column in the middle of the upper floor, and the validity of the assumed load-bearing formula is verified. It is to verify.

  Test specimen specifications are shown in Table 3, and a specimen figure (only specimen No. 1 as a representative example) is shown in FIG.

  In the method of applying force, positive and negative alternating shear is performed under a constant axial force (axial force ratio η = 0, +0.15, +0.4) according to the applied cycle shown in FIG. 8 by controlling the horizontal displacement of the applied point. Give force.

  The CFT column base bending moment-member deformation angle relationship (shear force-member deformation angle relationship is also shown) of each specimen is shown in FIGS. In addition, as a representative example, the specimen No. FIG. 15 shows the destruction state when R = + 1.0% and 5.0% (final destruction) in 1.

  In FIG. 15, as a representative example, the specimen NO. 1 shows a state of destruction, but other specimens NO. Nos. 2 to 6 also have a specimen No. 1, the outermost principal bar 7 near the boundary portion P between the root winding steel pipe portion 6 and the RC column 3 yielded, and the concrete above the boundary portion P (RC column 3) was peeled off. In the joint structure A between the CFT column and the RC column, the concrete 8 inside the root winding steel pipe portion 6 is not shear-destructed by being configured to satisfy the conditions of the above formulas (1) to (5). It was confirmed. Even in the configuration in which the shear reinforcement is not provided inside the CFT column 2 including the root winding steel pipe portion 6 as in test body No. 6, the concrete 8 inside the root winding steel pipe portion 6 is subject to shear failure. It did not come.

  As shown in FIG. 13, test body No. 5 has no axial force, resulting in a small hysteresis loop area and low energy absorption capacity.

  As mentioned above, although one Embodiment of the joining structure of the CFT pillar and RC pillar concerning this invention was described, this invention is not limited to said one Embodiment, It can change suitably in the range which does not deviate from the meaning. is there.

1 Multi-layer logistics facility (warehouse)
DESCRIPTION OF SYMBOLS 1a Lower layer part 1b Upper layer part 2 CFT pillar 2a Top part 3 RC pillar 4 Steel beam 5 Steel pipe 6 Root winding steel pipe part 6a Top part 6b Bottom part 7 Main reinforcement 8 Concrete 9 Stiffening part 10 Fixing plate 11 Deck plate 12 Slab reinforcement 13 Slab concrete 14 Donut Spacer 15 Guide angle 16 Reinforcement unit 17 Form A Joint structure of CFT column and RC column

Claims (5)

A structure for joining a lower CFT pillar and an upper RC pillar,
At the upper end portion of the CFT pillar, a root winding steel pipe portion formed in a shape extending a steel pipe upward is provided,
The joint structure of the CFT column and the RC column, wherein the main reinforcement of the RC column is inserted into the inside of the neckband steel pipe portion, and concrete is cast and filled in the inside of the necklace steel pipe portion.   The joint structure of a CFT column and an RC column according to claim 1, wherein the root winding steel pipe portion includes a stiffening portion protruding inward from an inner surface. In the junction structure of the CFT pillar and RC pillar of Claim 2,
As a condition for stress transmission,
The element of bending moment is divided into the RC column part from the height of the inflection point of the RC column to the switching height of the top of the root winding steel pipe part, and the beam directly below that is connected to the CFT column from the switching height. A first lever part to the upper end and a second lever part from the stiffening part to the bottom part of the root winding steel pipe part;
The CFT column and the RC column are joined so that the bending stress and the additional shear force of the first lever part and the second lever part satisfy the following formulas (1) to (5): Construction.
Where a is the distance from the switching height to the inflection point height, M1 is the bending moment at the bottom height position of the root winding steel pipe, Q is the shearing force at the inflection point height position, and h1 is from the switching height. The distance to the stiffening part, he is the distance from the root winding steel pipe to the switching height, h2 is the distance from the bottom of the root winding steel pipe to the top of the beam directly below the CFT column, and h0 is connected to the CFT column The distance from the upper end of the beam just below to the stiffening portion, R1 is the shearing force at the height position of the stiffening portion, and R2 is the shearing force at the upper end height position of the beam directly below the CFT column.   The CFT pillar and RC as described in any one of Claim 1 to 3 with which the fixing plate which fixes this principal reinforcement to the concrete inside the said neck winding steel pipe part is provided in the lower end part of the principal reinforcement of the said RC pillar. Column connection structure.   The joint structure of the CFT column and RC column as described in any one of Claim 1 to 4 which has a reinforcing bar extended in the up-down direction and arrange | positioned across the boundary part of the said root winding steel pipe part and the said RC column.