JPH0788690B2 - Structure of beam-column joint of steel pipe concrete column with X-shaped reinforcement - Google Patents

Description

TECHNICAL FIELD The present invention relates to a structure of a beam-column joint portion of a steel pipe concrete column with a built-in X-shaped bar arrangement.

[Prior Art] A steel pipe concrete column made by placing concrete inside a steel pipe has the same concrete restraining effect as that of a steel pipe in which the pitch of hoop bars is zero. Therefore, it is necessary to improve the concrete axial strength. However, if the outer steel pipe buckles, the restraining force in the circumferential direction cannot be expected, and the yield strength of the column may drop sharply. It is also proposed to provide a separating material between the steel pipe and concrete so that the steel pipe receives only the restraining force in the circumferential direction without applying an axial force. However, there is a problem that the axial force from the beam is difficult to be transmitted to the concrete inside because of the lack of integrity.

In order to prevent such inconvenience and increase the toughness of the column, it is effective to use a steel pipe concrete column with a built-in X-shaped bar, that is, to perform X-shaped bar arrangement in the concrete of the steel pipe concrete column. However, it has been confirmed by experiments in recent years.

[Problems to be Solved by the Invention]

However, in a steel pipe concrete column with a built-in X-shaped bar, there are many problems to be solved such as how to connect the upper and lower X-shaped bars and what kind of structure should be used for the beam-column joints. .

In view of such a current situation, the present invention provides a structure of a joint part of a steel pipe concrete column with a built-in X-shaped bar having good workability.

[Means for Solving the Problems]

The technical means taken by the present invention to achieve the above object are as follows. That is, the structure of the joint portion of the steel pipe concrete column with built-in X-shaped bar arrangement according to the present invention is such that the steel outer cylinder and the upper and lower end portions of the outer cylinder have inner end portions protruding from the upper and lower end portions of the outer cylinder, respectively. At the upper end of the steel pipe with a built-in X-shaped bar consisting of a pair of upper and lower steel inner cylinders fixed to each other and an X-shaped bar fixed between the upper and lower inner cylinders, an inner diameter approximately equal to the outer diameter of the inner cylinder is provided. A joining portion steel pipe unit including a steel tubular body and a beam joining plate projecting outward from the tubular body is arranged in a state in which the tubular body is externally fitted to a portion projecting from the upper end of the outer cylinder of the inner cylinder. Then, the upper end of the outer cylinder and the lower end of the cylinder are welded together, and the X-shaped pipe is attached to the upper end of the joint steel pipe unit.
A steel pipe with an X-shaped rebar similar to the steel pipe with a built-in rebar is arranged such that a portion of the lower inner cylinder of the steel pipe with a built-in X-shaped rebar projecting from the lower end of the outer cylinder is fitted into the tubular body. The lower end of the inner cylinder and the upper end of the cylindrical body are welded together, and concrete is placed inside the X-shaped rebar built-in steel pipe and the joint steel pipe unit.

As the steel outer cylinder and the steel inner cylinder of the X-shaped bar-incorporating steel pipe and the steel cylinder of the joint steel pipe unit, any shape such as a circular cross section and a rectangular cross section can be selected.

[Action]

According to the above configuration, the upper and lower X-shaped reinforcements are not directly joined one by one, but the outer cylinders to which the respective X-shaped reinforcements are fixed via the inner cylinder are interposed therebetween. Since the welding is performed through the joint steel pipe unit, the joining work is easy.

In addition, the joint steel pipe unit and the steel pipes with built-in X-shaped bar arranged above and below the joint steel pipe unit and the protruding portion of the inner cylinder of the steel pipe unit with built-in X-shaped joint are fitted to each other. It is easier, and when welding the tubular body of the joint steel pipe unit and the outer casing of the steel pipe with built-in X-shaped bar arrangement, the protruding portion of the inner casing fitted inside the tubular body is also used as the backing, Easy to join by welding.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the structure of a beam-column joint of a steel pipe concrete column with a built-in X-shaped bar. In the figure, 1 is a steel pipe with a built-in X-shaped bar, 2
Is a steel pipe unit for joints, 3 is concrete cast in-situ, 4 is a steel frame beam, and W is a welded portion of the steel pipe 1 with X-shaped reinforcing bar and the steel pipe unit 2 for joints.

As shown in FIGS. 2 and 3, the steel pipe 1 with a built-in X-shaped bar is
A steel outer cylinder 5 and a pair of upper and lower steel inner cylinders 6a, 6b fixed to the inside of the upper and lower end portions of the outer cylinder 5 by welding or the like such that the end portions project from the upper and lower end portions of the outer cylinder 5, respectively. And the upper and lower inner cylinders 6a,
It is composed of X-shaped bar arrangement 7 ... As shown in FIG. 3, the X-shaped bar arrangement 7 ... is shown by a diagonal line (indicated by a solid line arrow) inclined clockwise in a plan view and an oblique line (indicated by a dashed line arrow) inclined in a counterclockwise direction. ) And a substantially drum shape, and a hollow portion into which a tremie tube (not shown) can be inserted and removed is formed in the central portion. Further, as shown in FIG. 1, the X-shaped bar arrangement 7 ...
Although it has substantially vertical portions 7b at the upper and lower ends of the diagonal line 7a.
These parts 7a are located inside the column-beam joint (between the upper and lower ends of the beam 4) so as not to become a weak point of shear strength.
It is located at. The number of X-shaped bar arrangements 7 ... Is 16 in the drawing, but the number, spacing, etc. should be set appropriately.

When setting the number and intervals of the X-shaped reinforcing bars 7 ..., consideration must be given to the combination so that mutually intersecting reinforcing bars do not contact each other. The following two types can be considered as examples.

One of them is the bar arrangement shown in FIG. This is the fourth
As shown in FIGS. (A) and (B), two types of X-shaped reinforcing bars, that is, case α ₁ and case α _{2 each} composed of eight diagonal reinforcing bar groups, are combined. In the figure, a solid arrow indicates a clockwise diagonal streak, a dashed arrow indicates a counterclockwise diagonal streak, a ◯ at the base of the arrow indicates a column base position, and an arrow tip indicates a stigma position. R is the radius of the X-shaped rebar group at the stigma and pedestal position,
r ₁ and r ₂ are radii of the inscribed circle of the X-shaped reinforcing bar group, and α is a coefficient (angle) representing the position of the X-shaped reinforcing bar structure surface.

difference _{cosα 1/2 = r 1 /} R cosα 2/2 = r 2 / R α 1 and alpha ₂ appears as a difference of radius r _1, r ₂ of the inscribed circle. In FIG. 4 (a), θ is an angle that can be taken by the diagonal line in the counterclockwise direction indicated by a virtual line with respect to the diagonal line in the clockwise direction. In this angle range, there are infinite number of X-shaped bar arrangements.

However, as shown in FIGS. 5 (a) and 5 (b), when the clockwise diagonal line and the counterclockwise diagonal line are parallel to each other, they are combined to form a complete multi-directional X-shape. It becomes a bar arrangement. In the illustrated embodiment, the steel outer cylinder 5 and the steel inner cylinders 6a, 6b of the X-shaped bar-incorporating steel pipe 1 and the steel cylinder 9 of the joint steel pipe unit 2 have circular cross sections, respectively. However, these 5, 6a, 6b, 9 are the steel bars of the phantom line in Fig. 5 (a) in the case of the example of the reinforcement by the eight reinforcing bars shown in Fig. 5 (a) and (b). The inner cylinders 6a and 6b can each have a rectangular cross section.

The second example of bar arrangement is, as shown in FIG. 6 and FIG.
That is, the diagonal diagonal groups in the clockwise direction are arranged on the outer side (or the inner side) and the diagonal diagonal groups in the counterclockwise direction are arranged on the inner side (or the outer side) so that the reinforcing bars crossing each other do not hit each other. In the figure, 11 is a ring-shaped member that connects the inner and outer rebar groups to each other, and 12 is a nut that is screwed into each rebar, and is in contact with both upper and lower surfaces of the ring-shaped member 11. However, in this case, in addition to the upper and lower ring-shaped members 11 and 11 being prone to become obstacles during concrete pouring, there is the following structural problem.

That is, in the example of the bar arrangement in which the two types of X-shaped rebar groups of the case α ₁ and the case α ₂ described above are combined, as shown in FIG. 8A, both the case α ₁ and the case α ₂ are clocked. The diagonal diagonal line and the counterclockwise diagonal line are symmetrical,
Although balanced, in the bar arrangement examples of FIGS. 6 and 7, as shown in FIG. 8 (b), the diagonal bars in the clockwise direction a and the diagonal bars in the counterclockwise direction b are configured. The X-shaped bar arrangement is unbalanced and the structure is one-sided.

Therefore, in such a case, it is necessary to reduce the difference between the outside and the inside as much as possible. For example, as shown in FIGS. 9 and 10, the ring-shaped members 11 and 11 are formed into a tubular shape having a plate surface in the vertical direction, and the reinforcing bars are fixed to the inner surface and the outer surface thereof.

As shown in FIG. 11 and FIG. 12, the steel pipe unit 2 for the joint portion has a steel tubular body 9 having an inner diameter substantially equal to the outer diameters of the inner barrels 6a and 6b, and an outward projecting portion from the tubular body 9. Beam connection plate 10
It consists of and.

Then, as shown in FIG. 1, the joint steel pipe unit 2 is externally fitted to the upper end of the X-shaped reinforcing steel pipe 1 at the portion where the cylindrical body 9 projects from the upper end of the outer cylinder 5 of the inner cylinder 6a. Place it
The upper end of the outer cylinder 5 and the lower end of the tubular body 9 are welded W, and the upper end of the joint steel pipe unit 2 is a steel pipe 1 with an X-shaped bar arrangement similar to the steel pipe 1 with a built-in X-shaped bar arrangement, The lower inner cylinder 6b of the steel pipe 1 with the X-shaped bar arrangement is arranged so that the portion protruding from the lower end of the outer cylinder 5 is fitted into the cylindrical body 9, and the lower end of the inner cylinder 6b and the cylindrical body 9 are arranged. Weld W with the upper end and
Concrete 3 is placed inside the steel pipes 1 and 1 with built-in shape reinforcement and the joint steel pipe unit 2.

As shown by phantom lines in FIG. 1, hoop reinforcements 8 for confined concrete may be wound around the X-shaped reinforcements 7 ... When welding the X-shaped rebar built-in steel pipes 1 and 1 and the joint steel pipe unit 2, each member may be brought into the site in a separated state, and each member may be joined while being built. As shown in the figure, it is also possible to manufacture in advance members for the layers corresponding to the method of building at one time in the factory or on site, and lift and add the members. Further, when placing the concrete 3, it is desirable to use a tremie pipe to sequentially press the concrete 3 from below. In the beam-column joint by on-site work, concrete 3 up to the intermediate level in the vertical direction of the tubular body 9 of the joint steel pipe unit 2 is used.
The concrete pipe 3 is to be spliced after the steel pipe 1 is cast and the steel pipe 1 with the X-shaped reinforcing bar is joined above. In the illustrated embodiment, the outer cylinder 5 is also a pillar structural member like the cylindrical body 9,
Although the wall thickness is large, the outer cylinder 5 may be made of a thin steel plate and used as a pillar discard mold. Further, the joint portion steel pipe unit 2 is a beam joint plate for a steel pipe formed of a steel plate.
Although it was constructed by welding 10, centrifugal cast steel pipe (G
Column) may be used.

〔The invention's effect〕

The present invention is configured as described above, and does not directly connect the upper and lower X-shaped bar arrangements one by one, but the outer cylinders to which the X-shaped bar arrangements are fixed via the inner cylinders. Since welding is performed through the intervening joint steel pipe unit, the joining operation is easy.

In addition, the joint steel pipe unit and the steel pipes with built-in X-shaped bar arranged above and below the joint steel pipe unit and the protruding portion of the inner cylinder of the steel pipe unit with built-in X-shaped joint are fitted to each other. It is easier, and when welding the tubular body of the joint steel pipe unit and the outer casing of the steel pipe with built-in X-shaped bar arrangement, the protruding portion of the inner casing fitted inside the tubular body is also used as the backing, Easy to join by welding.

[Brief description of drawings]

The drawings show one embodiment of the present invention, FIG. 1 is a vertical cross-sectional view showing the structure of a beam-column joint portion of a steel pipe concrete column with a built-in X-shaped bar, and FIG. 2 describes the structure of a steel pipe with a X-shaped bar. FIG. 3 is a schematic plan view for explaining the structure of a steel pipe with a built-in X-shaped bar arrangement, FIG. 4 (a), (b) and FIG. 5 (a), (b).
Are explanatory views of the X-shaped bar arrangement, respectively, and FIGS. 6 and 7 are perspective views and schematic plan views showing other examples of the X-shaped bar arrangement, FIG. 8 (A),
(B) is a conceptual diagram for explaining the structural function of the X-shaped bar arrangement, and FIGS. 9 and 10 are perspective views and schematic views showing examples of improvement of the X-shaped bar arrangement shown in FIGS. 6 and 7. A plan view, FIG. 11 is a partially cutaway schematic perspective view showing a state in which a steel pipe with a built-in X-shaped bar and a joint steel pipe unit are joined, and FIG. 12 is an exploded perspective view of a main portion. 1 ... Steel pipe with built-in X-shaped bar, 2 ... Joint steel pipe unit,
3 ... Concrete, 4 ... Beam, 5 ... Outer cylinder, 6a, 6b ...
… Inner cylinder, 7 …… X-shaped bar arrangement, 9 …… Cylindrical body, 10 …… Beam connection plate.

Claims (3)

[Claims] 1. A steel outer cylinder, a pair of upper and lower steel inner cylinders fixed to the insides of the upper and lower end portions of the outer cylinder in such a manner that the end portions project from the upper and lower ends of the outer cylinder, respectively. A steel tube having an inner diameter substantially equal to the outer diameter of the inner cylinder, and a steel tube having an inner diameter substantially equal to the outer diameter of the inner cylinder protruding to the upper end of an X-shaped bar-incorporating steel pipe composed of X-shaped reinforcements fixed between the inner cylinders. A joint portion steel pipe unit including a beam joint plate is arranged in a state in which the tubular body is externally fitted to a portion of the inner barrel protruding from the upper end of the outer barrel, and the upper end of the outer barrel and the lower end of the barrel are arranged. Welded, and at the upper end of the joint steel pipe unit, a steel pipe with a built-in X-shaped reinforcement similar to the steel pipe with a built-in X-shaped reinforcement was projected from the lower end of the outer cylinder of the lower inner cylinder of the steel pipe with X-shaped reinforcement. The part is arranged so as to be fitted inside the cylinder body, and the lower end of the inner cylinder and the upper end of the cylinder body are welded together to form the X-shaped arrangement. Internal steel pipe and the internal structure of the beam-column joints of X-shaped reinforcement built steel Konkuto columns formed by Da設 the concrete joint steel pipe unit. 2. A steel outer cylinder and a steel inner cylinder in the X-shaped built-in steel pipe and a steel cylinder in the joint steel pipe unit have circular cross sections, respectively. Structure of beam-column joint of steel pipe concrete column with built-in reinforcement. 3. The X according to claim 1, wherein each of the steel outer cylinder and the steel inner cylinder of the X-shaped reinforcing steel pipe and the steel cylinder of the joint steel pipe unit has a rectangular cross section. Structure of beam-column joint of steel pipe concrete column with built-in reinforcement.