JP4298678B2 - Connection structure - Google Patents

Description

  The present invention relates to a technique for connecting beam main bars.

  A connection method using a reinforcing bar (referred to as a reinforcing bar lap joint) has been proposed as a connecting method of the beam main bar. The reinforcing bar lap joint is a connection method in which a separate reinforcing bar is superimposed on the beam main bar at the connection site of the beam main bar, and the beam main bars are connected coaxially. Since the beam main bars are connected on the same axis, it is highly convenient particularly when the beam is constructed by connecting the PCa members. In other words, there is no need to relatively shift the position of the beam main bars to be connected as in the case of the connection method in which the beam main bars are connected to each other, so that each PCa member has the same (the same beam main bar position). ) Can be used. The reinforcing bar lap joint is shown, for example, in FIGS.

JP 2004-308320 A

  When placing concrete at the connection portion of the main beam of the beam, generally, the concrete is vibrated by a vibrator or the like so that the concrete flows well to every corner of the formwork or the like. On the other hand, if vibration is applied to the concrete, the reinforcing bar may fall off the beam main bar, so that both are generally fixed and bound using a binding line. However, since the cross section of the beam main reinforcing bar and the reinforcing bar is substantially circular, the reinforcing bar may roll around the beam main bar even if it is fixed and bound.

  In this regard, in Patent Document 1, since the reinforcing bar is arranged so as to contact both the beam main bar and the ribbed bar, the reinforcing bar can be prevented from rolling around the beam main bar. However, in the configuration of Patent Document 1, a reinforcing bar enters between adjacent beam main bars, and the interval between adjacent beam main bars becomes narrow. When the space between the beam main bars on the lower end surface side of the beam becomes narrow, there is a problem that it is difficult to fill the cover portion on the lower end surface side of the beam with concrete. Particularly in high-rise buildings, the number of beam main bars tends to increase, and the problem of difficulty in filling concrete into the cover portion on the lower end surface side of the beam becomes significant.

  In addition, in the reinforcing bar lap joint, it is necessary to overlap the reinforcing bar over a predetermined length from the connection end of the beam main bar in order to ensure the strength of the joint portion. However, when this overlap length becomes long, especially when a beam is constituted by a PCa member, the number of spot casting portions of concrete increases, so the advantage of using the PCa member that concrete spot casting can be reduced.

  The present invention has been made in view of such a problem, and prevents rolling of the reinforcing bar relative to the main beam of the beam, ensuring the filling of the concrete, and shortening the overlapping length of the reinforcing bar and the main beam of the beam. The purpose is to solve all at once.

  According to the present invention, there is a connection structure for connecting between the main bars of the beam, the main bars connecting the beam main bars facing each other substantially coaxially, and the main bar connecting section being embedded in the main bar connecting section. A concrete portion, and the main bar connecting portion includes a reinforcing bar arranged to overlap between the beam main bars, and the reinforcing bar is connected to the pair of beam main bars. A plurality of the contact bars are arranged in contact with each other, and are arranged inward of the concrete portion from the plane passing through the axis of each of the beam main bars on which the reinforcing bars are superimposed and the beam main bars adjacent to the beam main bars. A connection structure is provided that is characterized by the above.

  In the connection structure of the present invention, the plurality of reinforcing bars are superposed on the beam main bars in a state of being in contact with each other. For this reason, when a certain reinforcing bar tries to roll around the beam main bar, the other reinforcing bars act so as to prevent this, and each reinforcing bar can be prevented from rolling around the beam main bar.

  In addition, the reinforcing bars are arranged inward of the concrete part rather than the planes passing through the axis of the beam reinforcing bar and the beam reinforcing bar adjacent to the beam reinforcing bar. The passing area is not narrowed and the filling property of the concrete is ensured.

  Furthermore, by arranging a plurality of reinforcing bars, the area where the reinforcing bars and the concrete are in contact with each other is increased as compared with a single case, and the adhesion to the concrete is improved. For this reason, the strength of the joint portion of the main beam of the beam is improved, and the overlapping length of the reinforcing bar and the main beam of the beam can be further shortened. In the present invention, the beam main bars are a plurality of upper beam main bars arranged substantially parallel on the upper end surface side of the beam, and a plurality of lower beam main bars arranged substantially parallel on the lower surface side of the beam, The reinforcing bar may be arranged in a range between a plane passing through each axis of the plurality of upper beam main bars and a plane passing through each axis of the plurality of lower beam main bars. According to this configuration, the area through which the concrete passes between adjacent beam main bars is not narrowed at the lower end surface portion of the beam, where the concrete filling property is particularly problematic, and the concrete filling property is ensured.

  Further, in the present invention, a plurality of the reinforcing bars to be overlapped between a set of the beam main bars are fixed to each other in advance, and are fixed to be overlapped between the beam main bars in a fixed state. Can be adopted. According to this configuration, since the plurality of reinforcing bars are fixed to each other in advance, the relative movement of the reinforcing bars is prevented, and each reinforcing bar can be more reliably prevented from rolling around the beam main bar. . Moreover, the workability at the time of disposing the reinforcing bar on the beam main bar can also be improved. Examples of a method for fixing the plurality of reinforcing bars to each other include binding fixation and spot welding between the reinforcing bar ends.

  As described above, according to the connection structure of the present invention, it is possible to prevent the reinforcing bar from rolling with respect to the beam main bar, ensure the filling of the concrete, and shorten the overlap length between the bar and the main bar. Can be solved.

  FIG. 1 is a diagram illustrating an application example of a connection structure according to an embodiment of the present invention. The example of the figure assumes a case where the connection structure according to the embodiment of the present invention is applied to an RC structure in which a beam 2 is installed between columns 1 and an upper part of the beam 2 forms a floor slab. Yes. However, the present invention is applicable not only to RC structures but also to SRC structures. In the example of FIG. 1, the upper part of the beam 2 integrated with the floor slab is formed by post-casting concrete, and the middle part to the lower part are referred to as PCa members 11a and 11b (hereinafter collectively referred to as PCa member 11). These are connected by the connection structure described below.

  FIG. 2A is a structural diagram of the connection structure of the present embodiment, and FIG. 2B is a cross-sectional structure diagram of the main bar connecting portion of FIG. In this connection structure, two PCa members 11a and 11b are connected in the axial direction of beam main bars 12a and 12b (hereinafter collectively referred to as beam main bars 12), and the respective PCa members 11a and 11b are connected to each other. A main bar connecting portion 10 that protrudes and faces each other and connects the beam main bars 12a and 12b facing each other and between the beam main bars 15a and 15b on the floor slab side (hereinafter collectively referred to as the beam main bar 15). And a concrete part 13 which is post-placed in the gap between the PCa members 11a and 11b and in which the main reinforcement connecting part 10 is embedded. A plurality of beam main bars 12 are arranged substantially horizontally and substantially parallel on the lower end surface side of the beam 2, and a plurality of beam main bars 15 are arranged substantially horizontally and substantially parallel on the upper end surface side of the beam 2.

  In the construction, the concrete placement work of the concrete portion 13 is performed through the connection work of the beam main bars 12a and 12b and the connection work of the beam main bars 15a and 15b. The beam main bars 12 and the beam main bars 15 are provided with a plurality of ribs 14 at a plurality of locations. The stirrup 14 is arranged so as to surround the outer circumferences of the beam main bars 12 and 15.

  The beam main bars 12a and 12b and the beam main bars 15a and 15b are connected to each other by the following structure so that the end faces face each other, and are connected substantially coaxially. The main bar connecting portion 10 includes a reinforcing bar 16 disposed so as to overlap between the beam main bars 12a and 12b and between the beam main bars 15a and 15b. The reinforcing bar 16 is made of, for example, a deformed bar or a round bar, and any of them can be adopted. However, the round bar has low adhesion strength, and the overlap length (L1 + L2 in FIG. ), It is necessary to use a deformed bar.

  As shown in FIG. 2B, in the present embodiment, a plurality of reinforcing bars 16 are disposed between the pair of beam main bars 12a and 12b and between the pair of beam main bars 12a and 15b (two in the example in the figure). In addition, the reinforcing bars 16 are arranged so as to contact each other. FIG. 3A is a view showing the arrangement of the reinforcing bar 16 and the beam main bar 12 (the same applies to the beam main bar 15 except that it is upside down). In the example of the figure, the two reinforcing bars 16 and the beam main bars 12 are bound together by a binding line 17. Preferably, the binding line 17 binds the reinforcing bar 16 and the beam main bar 12 at a place where the binding line 17 does not overlap with the stirrup bar 14. Each reinforcing bar 16 touches the beam main bar 12 at points P1 and P2, respectively, and the reinforcing bars 16 touch each other at point P3.

  In the present embodiment, when one of the two reinforcing bars 16 rolls around the beam main bar 12, the other barb 16 acts so as to prevent this, and each of the reinforcing bars 16 moves around the beam main bar 12. Can be prevented from rolling. In the example shown in FIG. 3A, the points P1 to P3 are the vertices of the triangle, and the force action and reaction vectors are directed toward the sides of the triangle. In this case, a larger force is required as compared with the case where the reinforcing bar 16 is single as in the prior art. Therefore, each reinforcing bar 16 can be prevented from rolling around the beam main bar 12. Further, as shown in FIG. 3A, a recess R is formed between the two reinforcing bars 16. This recess R serves as a guide for improving the ease of attaching and fixing the reinforcing bar 16 to the beam main bar 12.

  Note that the two reinforcing bars 16 do not need to be in contact with each other over their entire length, and it is sufficient if they are in contact at a plurality of locations. Further, it is desirable that the two reinforcing bars 16 are fixed to each other in advance, and fixed to the main beam bars 12 and 15 while being fixed. The reinforcing bars 16 can be fixed together by, for example, binding and fixing with a binding wire 16a as shown in FIG. 3B, or spot welding between the reinforcing bars 16 as shown in FIG. Welding the portion 16b). By fixing the reinforcing bars 16 in this manner in advance, relative movement of the reinforcing bars 16 (rotation of the reinforcing bars 16 and the like) is prevented, and each reinforcing bar 16 is more reliably connected to the beam main bar 12, Rolling around 15 can be prevented. In addition, workability when the reinforcing bar 16 is disposed on the beam main bars 12 and 15 can be improved.

  Next, in the present embodiment, since the plurality of reinforcing bars 16 are used for the connection between the beam main bars 12 or 15, the area where the reinforcing bars and the concrete are in contact with each other as compared with the case where a single reinforcing bar is used as in the prior art. And the adhesion between the reinforcing bar and the concrete is improved. In general, the cross-sectional area (diameter) of the reinforcing bar is arbitrarily determined according to the bending moment acting on the beam. It is common.

The area T1 (surrounding surface area) between the reinforcing bar and the concrete when using a single reinforcing bar is defined as D1 for the diameter of the reinforcing bar and L for the total length.
Adhering area T1 = π × D1 × L
It is.

When the total cross-sectional area of the two添筋16 fitted to the cross-sectional area of the conventional single添筋^{(π × D 2/4)} , the diameter D2 of the two添筋16,
Diameter D2 = √2 / 2 × D1
And the adhesion area T2 has the same overall length,
Adhering area T2 = π × D2 × L × 2 = π × √2 × D1 × L
= √2 × T1
And the adhesion area expands by about 40%. Needless to say, the adhesion between the reinforcing bar and the concrete is often due to physical engagement by the shape of the contact surface. If the shape is the same, the larger the adhesion area, the better the adhesion strength. When the adhesion strength is improved, the overlap length (L1 + L2 in FIG. 2A) can be further shortened, and when the beam 2 is configured using the PCa members 11a and 11b as in the present embodiment, the post-strike Since the amount of concrete (the amount of the concrete portion 13) to be reduced is reduced, the advantage of using the PCa member that can reduce the on-site casting of the concrete is utilized.

  Returning to FIG. 2 (b), each reinforcing bar 16 is a plane S1 or S2 that passes through the axis of the beam main bar 12 or 15 on which it is superimposed and the left and right beam main bars 12 or 15 adjacent to the beam main bar 12 or 15. Rather than the inside of the concrete portion 13. In other words, the reinforcing bar 16 superimposed on the beam main bar 12 is disposed above the surface S2 and the reinforcing bar 16 superimposed on the beam main bar 15 is disposed below the surface S1. Is disposed within a range Q between the surfaces S1 and S2.

  By arranging the reinforcing bar 16 at such a position, the gap d between adjacent beam main bars 12 (and between 15) is narrowed by the reinforcing bar 16, and the region through which the concrete constituting the concrete portion 13 passes is narrow. Can be avoided. In particular, the cover part on the lower end surface side of the beam 2 is the part where the filling property of the concrete is the worst, and a sufficient space is secured between the beam main bars 12 so that the concrete passes between the beam main bars 12 and the cover part. The filling property of concrete is ensured.

  As described above, in the connection structure of the present embodiment, a plurality of reinforcing bars 16 are provided, and the reinforcing bars for the beam main bars are arranged by placing the reinforcing bars 16 inward of the concrete portion 13 with respect to the plane passing through the axis of the beam main bars 12 or 15. It is possible to realize the prevention of rolling of the steel, ensuring the filling property of the concrete, and shortening the overlapping length of the reinforcing bar and the main beam of the beam.

<Other embodiments>
In the above embodiment, the two reinforcing bars 16 are provided for each connection location of the beam main bars 12, 15, but three or more reinforcing bars may be used. As the number of the reinforcing bars 16 increases, the adhesion area increases even if the total cross-sectional area is the same. FIG. 3D is a diagram showing an example in which three reinforcing bars 16 are used. Further, each reinforcing bar 16 may have a different diameter. FIG. 3 (e) is a view showing an example in which two reinforcing bars 16 and three reinforcing bars 16 ′ having a diameter smaller than that of the reinforcing bars 16 are used.

  Moreover, in the said embodiment, although the linear thing was used as the reinforcing bar 16, what bent the edge part of the reinforcing bar 16 can also be employ | adopted. 4 (a) and 4 (b) are diagrams showing an example in which the end of the reinforcing bar is bent. In the example of FIG. 4 (a), the end of the reinforcing bar 161 is bent 90 degrees to form a hook shape. ing. In the example of FIG. 4B, the end of the reinforcing bar 162 is bent 180 degrees to form a hook shape. When the end portions are bent like the reinforcing bars 161 and 162, the bearing resistance generated at the bent portion is also effective in addition to the adhesion action, so that the overlap length can be further shortened.

  Moreover, although the beam using a PCa member was demonstrated in the said embodiment, the said connection structure is applicable also to the beam which does not use a PCa member (a beam which uses all concrete on-site). Furthermore, each butting position between the beam main bars can be shifted from each other in the full length direction of the beam, for example, in a staggered pattern. This is because, when a constant load acting on the beam is large, such as when the beam has a large span, if the abutting positions are in the same row, large cracks may be concentrated on that portion.

It is a figure which shows the example of application of the connection structure which concerns on one Embodiment of this invention. (A) is a structural diagram of the connection structure of the present embodiment, (b) is a cross-sectional structure diagram of the main bar connection portion of FIG. 2 (a). (A) is a figure which shows the arrangement | positioning aspect of the reinforcement 16 and the beam main reinforcement 12, (b) and (c) is a figure which shows the example of fixation of the reinforcement 16, (d) and (e) are the reinforcement 16 It is a figure which shows the other example of arrangement | positioning. (A) And (b) is a figure which shows the example which bent the edge part of the reinforcing bar.

Explanation of symbols

10 Main bar connecting portions 11a and 11b PCa members 12a and 12b Beam main bar 13 Concrete section 14 Stirrup 16 Additional bar

Claims (3)

It is a connection structure that connects between beam main bars,
A main bar connecting portion that connects the beam main bars facing each other substantially coaxially;
A concrete part that is placed in the main bar connecting part and in which the main bar connecting part is embedded,
The main muscle connecting portion is
A supplementary bar arranged between the beam main bars and superposed on them,
A plurality of the reinforcing bars are arranged in contact with each other with respect to the set of the main bars of the beam, and each axis of the main bar of the beam on which the additional bars are superimposed and the main axis of the beam adjacent to the main bar of the beam. A connection structure characterized in that the connection structure is disposed inward of the concrete portion with respect to a surface passing through. The beam main bars include a plurality of upper beam main bars arranged substantially parallel on the upper end surface side of the beam, and a plurality of lower beam main bars arranged substantially parallel on the lower surface side of the beam,
The accessory muscle is
2. The connection structure according to claim 1, wherein the connection structure is disposed in a range between a plane passing through each axis of the plurality of upper beam main bars and a plane passing through each axis of the plurality of lower beam bars. .   2. The plurality of reinforcing bars to be overlapped between a pair of beam main bars are fixed to each other in advance, and are fixed and overlapped between the beam main bars in a fixed state. Or the connection structure of 2.

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