JP2004027595A - Reinforcement joint and reinforcement joining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grout-filled reinforcement joint used in joining reinforcement end parts such as a shearing reinforcing bar in a superposed state and reducing the size and weight, and a reinforcement joining method using this joint. <P>SOLUTION: A joint body 2 is a cylindrical body of a cross-sectional almost rectangular shape, and its lumen part 8 is divided into two parts by a wall-like part 7 arranged in the lengthwise direction. A plurality of circular arc-shaped projections 9 are respectively arranged at a prescribed interval in the lengthwise direction on an inner peripheral surface of the respective divided lumen parts 8a and 8b for receiving a joining reinforcement. These circular arc-shaped projections 9 are formed almost along a peripheral surface except for a part of the wall-like part 7, and are low in the projecting height on the side of one flat part 22a, and the base part vicinity of the corresponding part side wall-like part 7 swells outside more than a circle, and becomes a passage 81 of a grout material.The reinforcement is inserted into the respective divided lumen parts 8a and 8b from both end opening parts, and the grout material is injected from an injection hole arranged on an outer peripheral surface of the joint body 2. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rebar joint for joining rebar used for reinforcing materials of various concrete structures, and a rebar joining method using the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a reinforced concrete structure (RC) or a steel reinforced concrete structure (SRC) has been frequently used in structures in the field of architectural civil engineering represented by buildings and bridges. In such structures as columns and beams, shear reinforcing bars (band bars and stirrups) are arranged at predetermined intervals in the longitudinal direction so as to surround a plurality of main bars (column bars and beam bars) juxtaposed in a rectangular tube shape. Is arranged. In these shear reinforcing bars, as a means for forming a closed shape, generally, an end portion of a reinforcing bar is bent into a 135 ° hook shape. However, when the extra length of the hook portion interferes with the arrangement of the reinforcing bars, the ends of the reinforcing bars are subjected to flare groove welding or mechanical joining by means of tubular reinforcing joints. In this case, instead of joining the ends of the reinforcing bars on the same axis like the main reinforcing bar for reasons such as workability, in any state, the reinforcing bar ends are overlapped by a predetermined length. Joined.
[0003]
As a conventional example of a rebar joint for the above-mentioned lap joint type, there is a wedge press-fit type proposed by the present applicant (Japanese Utility Model Publication No. 58-53880). This rebar joint has advantages in that the quality of the joint is more stable and the operation is simpler than in the case of welding, which is easily affected by weather conditions and the skill of the operator. However, since the hydraulic pump is used for press-fitting the wedge, when the rebar has a large diameter, there is a problem that the press-fitting device becomes large and the workability is inevitably reduced.
[0004]
It has also been proposed to apply a grout-filled type rebar joint, which is widely used for joining main rebars, to lap joints as a different type of rebar joint (Japanese Patent Application Laid-Open No. 63-55245). . That is, in this type of rebar joint, the inner space of the joint main body that receives two rebars is formed in an oval cross section, and the ends of the rebars are inserted from the openings at both ends. The rebar is placed in the joint body in a superposed state. Then, a grout material such as high-strength mortar or synthetic resin is injected without gaps from the injection holes provided in the peripheral wall into the internal voids, and the reinforcing bars are joined together by solidification. In this case, the load transmission between the reinforcing bars in the joined state mainly depends on the shear resistance of the grout material inserted between the nodes of the reinforcing bars. Further, in order to increase the adhesion between the joint body and the grout material, it is customary to provide a plurality of circular projections or arc-shaped projections such as continuous spiral projections on the inner wall surface of the joint body.
[0005]
[Problems to be solved by the invention]
The latter grout-filled rebar joint has the advantage that no special equipment is required for the joining operation, that the operation is simple, and that it is relatively easy to handle large-diameter rebars. However, since the joint structure relies on a grout material, which is inherently inferior in mechanical strength compared to metal materials, in order to obtain sufficient joint strength, the length of the fixing portion must be larger than in other mechanical joints. Need to secure. For this reason, there has been a problem that the overall length of the joint body is inevitably long, and it is difficult to reduce the weight and size.
[0006]
The inventors of the present invention have made intensive studies on such a grout-filled rebar joint, and have arrived at the present invention. That is, an object of the present invention is to provide a grout-filled rebar joint that can be reduced in weight and size.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, according to the present invention, a reinforcing rod is inserted through openings at both ends into a cylindrical joint body having an arc-shaped projection formed on the inner surface of a peripheral wall, and the inner joint is superposed in the inner space. In a rebar joint in which these rebars are joined via a grout material filled into an inner space from an injection hole formed in a peripheral wall, the joint main body has at least a part of the rebars in the inner space in the longitudinal direction. It is characterized by having a wall-like portion separated by a.
[0008]
According to this configuration, by providing the inner wall of the joint body with the wall-like portions that separate the reinforcing bars from each other, the binding force of the grout material is greatly improved. That is, in the conventional example in which the inner space of the joint main body for receiving the reinforcing bar is a single space, the injected grout material spreads between and around the two reinforcing bars, and solidifies as an integral unit. When a load is applied to the rebar in the pull-out direction, the grout material, especially between the two rebars, is simultaneously subjected to stresses in opposite directions by the rebars, so that the grout is easily broken even with a not so large load. it is conceivable that. On the other hand, in the rebar joint of the present invention, each grout material covering the periphery of each rebar is made of a material such as a steel material having a high mechanical strength that constitutes the joint body over the entire periphery of the portion where the wall-shaped portion exists. Surrounded by For this reason, each grout material is substantially unaffected by the behavior of the other reinforcing bar described above, and is restrained only by the joint body, so that a strong restraining force is obtained for the reinforcing bar. Therefore, in the rebar joint of the present invention in which the effect of filling the grout material is effectively exerted, it is possible to reduce the length of the fixing portion between the rebars. Further, the presence of the wall-shaped portion greatly contributes to the improvement of the rigidity of the joint main body, so that the thickness of the peripheral wall of the joint main body can be made thinner than the conventional one. Thus, the weight and size of the joint body are reduced.
[0009]
Furthermore, in the rebar joint of the present invention, it is preferable that the wall-like portion is provided at least at both ends of the joint body. That is, in a conventional grout-filled rebar joint having no wall-shaped portion in the inner space, when the rebars are pulled by an excessive load, a crack is first generated in the grout material near the opening of the joint body, It gradually expands inward. As a result, the grout material loses its original function of restraining force, and the reinforcing bar comes off. On the other hand, in the case where the wall portions are provided at both ends of the joint body, the grout material near the opening is constrained all around, and has a structure in which cracks hardly occur there. Therefore, when the wall-shaped portion is provided only in a part of the joint body, both end portions are more effective than the intermediate portion of the joint body, which is convenient for shortening the joint body.
[0010]
Further, the wall-shaped portion may be divided at a part in the longitudinal direction, and the grout material injection hole may communicate with the divided portion. In this case, the grout material injected from the outer peripheral surface side of the joint main body is smoothly distributed to the respective inner cavities divided by the wall-shaped portions at the divided portions. For this reason, it is not necessary to provide an injection hole for each of these hollow portions, and the workability is not reduced due to the provision of the wall portion.
[0011]
Further, in the present invention, the following configuration can be adopted as a suitable means. That is, when a grout material flow path that is continuous in the longitudinal direction is provided on the injection hole side of the wall-like portion, the grout material filling operation becomes smoother and more reliable. Further, when the injection hole side of the arc-shaped projection is formed so as to be lower than the projection height on the opposite side in the radial direction, it is convenient when the covering thickness of the concrete is reduced. In addition, the reinforcing joints having these configurations can be further reduced in weight and size in combination with a grout material containing appropriate reinforcing fibers such as steel fibers. By using such a grout material, the joining operation of the rebar can be greatly improved.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
The rebar joint according to the present invention is not particularly limited in its use place, and can be widely applied when various rebars are joined in a lap joint state. Therefore, the structure is applicable to both new and existing structures. Generally, it is suitably used for joining shear reinforcing bars in a concrete structure. In this case, in addition to applying it to the end of one reinforcing bar bent annularly to make it a closed shape, depending on the size of the column or beam, a plurality of reinforcing joints and one or more reinforcing bars Reinforcing bars can also be used.
[0013]
In the present invention, as a method of injecting the grout material into the joint main body, for example, a funnel may be applied to an injection hole to inject the grout material by natural fall, or may be press-fitted with an appropriate injection gun. In any case, dense filling is important. Therefore, it is desirable to provide a flow path of a grout material that is continuous in the longitudinal direction in the inner space of the joint body that receives the reinforcing steel. As a method for forming such a flow path, for example, as in an example described later, for example, the cross-sectional shape of the insertion portion of the reinforcing bar separated by the wall-shaped portion is not made circular, but a part of the cross-section protrudes outward. It is convenient to form the grout material so that the grout injection hole communicates near the flow channel. In addition, an exhaust hole for facilitating the entry of the grout material may be provided on the outer peripheral surface of the joint main body, and may be used for checking the filling state of the grout material, and it is of course possible to provide a plurality of injection holes.
[0014]
Further, the grout material applicable to the rebar joint of the present invention may be a general grout material such as mortar or synthetic resin as it is, but this is obtained by mixing reinforcing fibers having excellent tensile strength such as steel fibers. Is particularly suitable in combination with the joint body having the wall-shaped portion. The reinforcing fibers other than the steel fibers include carbon fibers, aliphatic or aromatic polyamide fibers, polyolefin fibers, glass fibers, and ceramic fibers. The compounding of such reinforcing fibers has the effect of improving the shear resistance of the grout material, whereby the grout material containing the reinforcing fibers is pulled out of the rebar together with the restraining effect of the wall portion inside the joint body. It greatly contributes to strength improvement. In the present invention, in view of dispersibility in the grout material and fluidity of the kneaded material, that is, the kneading work of the grout material and the filling property into the void portion inside the joint body are preferably formed into short fibers. . Among them, short-fiber steel fibers are preferable from the viewpoint of price and compounding effect, and those manufactured by various methods such as cut wire fiber, shear fiber, melt extraction fiber, and cutting fiber can be applied.
[0015]
The effect when the reinforcing fibers are mixed in the grout material will be described by taking a combination of steel fibers and a mortar grout material as an example. First, comparing the mechanical properties of the raw materials themselves, the compressive strength of a normal grout material in a solidified state is about 1/2 to 1/10 of that of steel, and its shear strength is about 1/10 of the compressive strength. is there. On the other hand, the compressive strength and the tensile strength of the steel material are the same, and the shear strength is only about 1 / √3 thereof, which is ten times or more the strength of the grout material. Furthermore, as a characteristic of the grout material, when a crack is generated due to external force, the strength is reduced at an early stage, but the steel material has a higher mechanical strength than the grout material and does not suddenly decrease in strength, and the strength gradually increases with deformation. There is a property to decrease. Then, in the grout material in which the steel fibers are mixed, the steel fibers are oriented in all directions and resist external force. For this reason, the grout material has a higher compressive strength and a higher shear strength than those containing no steel fiber, and even if a crack occurs, the grout material is ductilely broken by the presence of the steel fiber. Such grout material is filled between the joint body and the reinforcing bar, and the stress transmission between them is mainly shearing force, and the steel fibers dispersed in the grout material work effectively on it. This reinforcing effect is the same even with other reinforcing fibers, although the degree is different. If such a grout material is used, the length of the fixing portion of the reinforcing bar, that is, the entire length of the joint body can be further reduced.
[0016]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 are a front view, a plan view, and a left side view, respectively, of an embodiment of a rebar joint according to the present invention. In the illustrated rebar joint 1, the joint main body 2 is a cylindrical body having a substantially elliptical cross section (oval shape) as seen from FIG. 3 and the like, and is formed by casting. Both end portions of the joint main body 2 are formed to be slightly larger than the intermediate portion in the radial direction, and the bulging portion 21 is provided with two insertion ports 3 respectively. These bulging portions 21 take into consideration the reinforcement of the ends that play an important role as described above. In order to further reduce the size, the inner diameter near the insertion port 3 is reduced, but may be expanded inward. As shown in FIG. 1, in the outer peripheral surface of the joint body 2, an injection hole 4 of a grout material is opened at one position on the axis in one flat portion 22 a, and the axis is formed substantially at the center in the longitudinal direction. Two screw holes 5 are formed slightly away from each other. In addition, a bolt (not shown) is screwed into the screw hole 5, and until the grout material is injected and solidified, the rebar is temporarily fixed by tightening the bolt. Further, exhaust ports 6 are provided at the four corners of one flat portion 22a.
[0017]
FIG. 4 to FIG. 7 are cross-sectional views of each part for describing the internal structure of the joint body 2. The inner space 8 of the joint body 2 is substantially divided into two by a flat wall-like portion 7 provided along the longitudinal direction thereof, and the divided inner spaces 8a and 8b receive rebar. Has become. The inner diameters of the divided inner cavities 8a and 8b are formed somewhat larger so that the inner diameters of the divided inner cavities 8a and 8b are loosely fitted when the rebar is inserted. The wall-shaped portion 7 is partially cut out and divided immediately below the grout material injection hole 4, but the wall-shaped portion 7 is continuous except at the cut-out portion 7 a, and both end surfaces of the joint main body 2 are provided. Has been reached. Further, a plurality of arc-shaped projections 9 are provided on the inner peripheral surface of the joint body 2 at appropriate intervals. As is apparent from FIG. 7, these arc-shaped projections 9 are provided over substantially the entire circumference of the inner surfaces of the divided inner cavities 8a and 8b except for a part of the wall-shaped portion 7. Here, the protruding height of each arc-shaped projection 9 is formed to be lower on one flat portion 22a side than on the other flat portion 22b side. Further, the cross-sectional shape of the divided inner space portions 8a and 8b is formed in a substantially semi-cylindrical shape in a place where the arc-shaped projection 9 does not exist, and is surrounded by the inner surface on one flat portion 22a side and the base of the wall-shaped portion 7. The corner portion 81 forms an appropriate gap continuous in the longitudinal direction when the reinforcing bar is inserted, and serves as a flow path for the grout material. Note that it is of course possible to form the arc-shaped projections 9 also on the wall-shaped portion 7.
[0018]
FIG. 8 is an explanatory diagram schematically showing a state in which the rebar joint 1 is applied to a column bar. Here, one strip bar B is installed so as to surround the four column main bars A arranged at the four corners of the rectangle, and the rebar joint 1 of the present invention is used for joining both end portions thereof. In this case, both end portions of the stirrup B are vertically overlapped, and the one flat portion 22a of the rebar joint 1 is attached to the overlapping portion so as to be located outside. That is, since the stirrup B is mounted eccentrically with respect to the reinforcing bar joint 1 so that the projection height of the arc-shaped projection 9 is lower, the outer dimension of the column can be reduced. Here, the injection hole 4 and the like are provided in one flat portion 22a, and nothing is formed in the other flat portion 22b. It is difficult to make mistakes when installing. It should be noted that it is not an essential requirement to provide a difference in the projecting height of the arc-shaped projections 9, and the divided inner cavities 8a and 8b for receiving the rebar need not be eccentric to one side.
[0019]
Next, a method of using the rebar joint 1 according to the present invention will be described with reference to FIGS. The step of inserting the ends of the stirrups B into the divided inner space portions 8a and 8b of the reinforcing bar joint 1 is, of course, before the outer stirrups of the stirrups B are fitted to the main column bars A and after the outer stirrups. Is also good. That is, the reinforcing bar joint 1 is temporarily attached to the column main bar A in a state of a closed ring, or the band bar B whose end is simply overlapped is fitted to the column main bar A as it is, and then the reinforcing bar joint 1 is mounted. can do. In the latter case, one of the split inner cavities 8a of the rebar joint 1 is fitted to one end of the stirrup B, and is inserted inward until it comes off the overlapping portion. Next, the other end of the stirrup B is inserted into the other divided inner space 8b, and the rebar joint 1 is returned to a position where each end of the stirrup B projects from the end face of the joint body 2 to the same extent.
[0020]
In the above-described insertion state, the reinforcing bar joint 1 and the stirrup B are merely loosely fitted, and may move from a predetermined position until the grout material is injected or when the solidification thereof is not sufficient. There is. For this reason, in this embodiment, a bolt for temporary fixing is screwed into the two screw holes 5, and the strap B can be fixed by tightening the bolts. It is also possible to use another temporary fixing means such as a clip instead of the bolt, and it is not necessary to use such temporary fixing means in some cases.
[0021]
Then, an appropriate grout material is injected into the reinforcing joint 1 in the temporarily fixed state through the injection hole 4. This injection method can be carried out by applying a funnel and dropping by gravity or by using an appropriate injection gun. The grout material flowing into the inside from the injection hole 4 is divided into the two divided inner spaces 8a and 8b in the notch portion 7a immediately below the grout material, and the flow path 81 formed on the one flat portion 22a side of the wall-shaped portion 7 is formed. And flows into the annular space between the arc-shaped projections 9 without fail. At this time, the air inside is pushed out by the presence of the exhaust port 6 and the flow of the grout material is smoothly performed, and by confirming that the grout material overflows from the exhaust port 6, it is determined whether or not the dense filling is performed. Can be confirmed. If the gap between the opening 3 and the reinforcing bar is large, it may be closed with an appropriate sealing material, cap, or the like. Further, when the injection hole 4 is located on the side as shown in the figure, After the grout material is injected, the injection hole 4 may be closed with an appropriate plug.
[0022]
Incidentally, the pull-out strength of the rebar was measured for the rebar joint 1 of the above-described embodiment and the rebar joint formed with the same dimensions as those of the embodiment except that no wall-shaped portion was present as a comparative example. The product was about 30% better than the comparative example. Therefore, when trying to obtain the same performance, it is possible to shorten the length of the joint main body 2 by that much, which leads to a reduction in the weight of the rebar joint 1. In addition, the grout material made of mortar mixed with steel fibers can improve the performance by about 50% as compared with a material not containing steel fibers, so that the reinforcing effect of the reinforcing joint 1 can be obtained in combination with the restraining effect of the wall portion. It greatly contributes to miniaturization and weight reduction.
[0023]
In the above embodiment, a plurality of independent substantially annular projections have been described as arc-shaped projections. However, the projections may be changed to a spiral one, or a wall-shaped part may be connected to form an injection hole in each divided inner space. There is no problem in doing so, and various modifications within the technical concept of the present invention are possible, such as making each of the divided inner spaces one by one without opening at both ends.
[0024]
【The invention's effect】
As described above, in the rebar joint according to the present invention, the wall-shaped portion is provided in at least a part of the longitudinal direction, and the inner space of the joint body is substantially divided into a plurality of portions, so that the inner space is inserted into the inner space. The effect of restraining the grout material covering the periphery of the provided reinforcing bar is enhanced, and the rigidity of the joint body itself is greatly improved. For this reason, it becomes possible to shorten the length of the fixing portion of the reinforcing bar, and further reduce the thickness of the joint body. As a result, the weight and size of the rebar joint can be reduced. This leads to a reduction in the amount of grout material used, and has a great effect on improvement in workability and cost in rebar joining together with an effect accompanying weight reduction and the like.
[0025]
Further, when the wall-like portion is provided in a part of the longitudinal direction, it is preferable to provide the wall-like portion on both ends of the joint body. In addition, it is possible to rationalize the grout material injection work by dividing the wall-shaped portion and opening a grout material injection hole in the divided portion or providing a flow path extending in the longitudinal direction along the wall portion. it can. Furthermore, it is possible to reduce the covering thickness of the concrete by eccentricizing the projecting height of the arc-shaped projection, and the use of a grout material mixed with reinforcing fibers such as steel fibers has the above-mentioned effect that these rebar joints have. It is effective in promoting.
[Brief description of the drawings]
FIG. 1 is a front view showing one embodiment of a rebar joint according to the present invention.
FIG. 2 is a plan view of the rebar joint shown in FIG.
FIG. 3 is a left side view of the rebar joint shown in FIG. 1;
FIG. 4 is a sectional view taken along line AA in FIG.
FIG. 5 is a sectional view taken along line BB in FIG. 1;
FIG. 6 is a sectional view taken along line CC in FIG. 1;
FIG. 7 is a sectional view taken along line DD in FIG. 1;
FIG. 8 is an explanatory view showing a use state of the reinforcing bar joint shown in FIG. 1;
[Explanation of symbols]
A: Main reinforcing bar, B: Shear reinforcing bar (band bar), 1: Reinforcing bar, 2: Joint body, 3: Insertion port, 4: Injection hole, 5: Screw hole, 6: Exhaust port, 7: Wall-shaped part, 7a: notch, 8: inner space, 9: arc-shaped projection

Claims (6)

Reinforcing bars are inserted into the cylindrical joint body having an arc-shaped protrusion formed on the inner surface of the peripheral wall from the openings at both ends, and are superposed in the inner space, and these reinforcing bars are injected into the injection hole formed in the peripheral wall. The joint body is provided with a wall-shaped portion that separates the rebars from each other at least in a part of the longitudinal direction in the inner space portion. Rebar joint. The rebar joint according to claim 1, wherein the wall-shaped portion is provided at least at both ends of the joint body. The rebar joint according to claim 1, wherein the wall-shaped portion is divided at a part in a longitudinal direction, and an injection hole communicates with the divided portion. The rebar joint according to any one of claims 1 to 3, wherein a flow path of a grout material that is continuous in a longitudinal direction is provided on an injection hole side of the wall-shaped portion. The rebar joint according to any one of claims 1 to 4, wherein an injection hole side of the arc-shaped projection is formed lower than an opposite side in a radial direction. The reinforcing bar is inserted into the reinforcing bar joint according to any one of claims 1 to 5, from the openings at both ends, and a grout material containing a reinforcing fiber is filled in the inner space to join the reinforcing bars. A method for joining reinforcing bars, characterized in that:

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