Reinforcing bar joined to primary bar, and joining method for reinforcing bar

Abstract

To provide: a reinforcing bar that can be easily joined to a primary bar and can reduce man-hours and costs; and a joining method for the reinforcing bar.SOLUTION: A bar body of a reinforcing bar 10 has a closed shape, and the reinforcing bar has a first joining gap 20 in the middle in a natural state. Male screws 12c of both end portions 12a, 12b of the bar body 12 are screwed into female screws 14c of a joining member 14 in a state in which both the end portions 12a, 12b of the bar body 12 are elastically deformed by external force so as to approach each other and are facing each other at a second joining gap 21 smaller than the first joining gap 20, so that elastic force in a direction of exiting from the joining member 14 acts on each of the end parts 12a, 12b of the bar body 12 due to the elastic restoring force of the bar body.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a reinforcing bar that is connected to the main bars of columns or beams in reinforced concrete, and a method for connecting the reinforcing bar. [Background technology]

[0002] Conventionally, when constructing concrete beams and columns, reinforcing bars are attached to the outer periphery of the main bars to improve their strength. In this case, the reinforcing bars are wrapped around the main bars and attached to the main bars by welding both ends of the reinforcing bars to each other or by hanging them on the main bars. However, the welding method does not provide stable quality and requires high-performance joints for welding, which is a factor in increasing costs. The method of hanging the reinforcing bars on the main bars makes the reinforcing bar structure complicated and makes it difficult to work on site.

[0003] It has been proposed to simplify the reinforcement structure and shorten the construction period by using threaded reinforcing bar joints as a method for connecting main bars (for example, Patent Document 1). This proposal also suggests providing a lock nut to eliminate rattling.

[0004] The performance criteria for reinforcing bar joints set by the government are divided into four grades: SA, A, B, and C. While the use of SA or A grades is permitted for main bars, B and C grade reinforcing bar joints are also permitted for reinforcing bars. The allowable slip amount when stress is applied is specified for SA and A grade reinforcing bar joints, but there is no regulation for the slip amount for B and C grade reinforcing bar joints. Therefore, when it comes to reinforcing bars, if the standard strength, rigidity, etc. are met, it is more advantageous to use B and C grade reinforcing bar joints in terms of avoiding costs and excessive quality requirements. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5869716 Summary of the Invention [Problem to be solved by the invention]

[0006] By using the threaded reinforcing bar joints as reinforcing bars, it is expected that the arrangement of reinforcement bars can be simplified and the construction period can be shortened. However, in order to achieve the required performance, it is necessary to provide a lock nut or use a reinforcing bar joint of SA or A class. Therefore, when a lock nut is provided, there is a problem that the labor required to tighten the lock nut to a specified torque is extra compared to when a lock nut is not provided. When a lock nut is not provided, it is difficult to realize a reinforcing bar joint of high performance such as SA or A class, and the cost of improving the thread accuracy of the reinforcing bar joint increases.

[0007] An object of the present invention is to enable easy attachment of closed-shaped reinforcing bars to main bars and to reduce the number of steps and costs required for connecting the reinforcing bars to connecting members. [Means for solving the problem]

[0008] The reinforcing bar of the present invention is A reinforcing bar that surrounds a plurality of main reinforcements from the outer periphery, The muscle body has a closed shape and has a first connecting gap in the middle in a natural state. The two ends of the muscle body are screw-connected by a connecting member while an external force causes the two ends to elastically deform toward each other and face each other with a second connecting gap that is smaller than the first connecting gap, and in the connected state, the elastic restoring force of the muscle body causes the male threads of the two ends to contact the female threads of the connecting member in the direction of removing the two ends from the connecting member.

[0009] According to this configuration, male threads are formed at both ends of the reinforcing bar body having the first connecting gap, and an external force is applied in the direction in which the reinforcing bar body closes, and the reinforcing bar body is screwed into the female thread of the connecting member. This causes an elastic restoring force to act on each end of the reinforcing bar body in the direction of coming out of the connecting member. As a result, the male thread and the female thread are in contact with each other with a certain force, and the connecting member is fixed to both ends of the reinforcing bar body, so that the tensile strength and rigidity required for the reinforcing bar can be secured without using a lock nut. This reduces the labor required to connect the reinforcing bar body to the connecting member, and since excessive performance is not required, it is possible to use inexpensive reinforcing bar joints with low tensile strength such as class B or class C. The closed shape refers to a shape that forms a closed area, such as a rectangle, a circle, or an ellipse.

[0010] The method for connecting reinforcing bars of the present invention comprises the steps of: When surrounding multiple main bars with reinforcing bars from the periphery, The muscle body is bent into a closed shape, and in its natural state, a first connecting gap is provided midway. The muscle body is elastically deformed by an external force so that both ends approach each other and face each other with a second connecting gap smaller than the first connecting gap.The two ends of the muscle body are then screw-connected by a connecting member, and in this connected state, the elastic restoring force of the muscle body brings the male threads of the both ends into contact with the female threads of the connecting member in the direction in which the both ends come out of the connecting member.

[0011] According to this method, male threads are formed at both ends of the reinforcing bar body having the first connecting gap, and an external force is applied in the direction in which the reinforcing bar body closes, and the reinforcing bar body is screwed into the female thread of the connecting member. This causes an elastic restoring force to act on each end of the reinforcing bar body in the direction in which it comes out of the connecting member. As a result, the male and female threads come into contact with each other with a constant force, and the connecting member is fixed to both ends of the reinforcing bar body, so that the performance required for the reinforcing bar can be secured without using a lock nut. This reduces the labor required to connect the reinforcing bar body to the connecting member, and since excessive performance is not necessary, it becomes possible to use inexpensive reinforcing bar joints such as class B or class C.

[0012] The main features of the present invention are: A plurality of muscle bodies each having a male thread formed at at least one end thereof; a connecting member having an insertion hole into which the male screw is inserted from both ends, The threads of the male screw are inserted into the insertion hole of the connecting member, A main bar in which the connecting member and the thread are joined by radial crimping.

[0013] This structure can achieve the same performance as main reinforcements connected by lap joints, which can save resources. Also, since there is no need to process female threads in the connecting members, costs can be reduced.

[0014] The reinforcing bar structure of the present invention is The outer periphery of a plurality of parallel-arranged main reinforcements is surrounded by the reinforcing bar of the present invention, and the intersections of the main reinforcements and the reinforcing bars are tied together with tie wires, A first portion of the binding wire wound around a main reinforcing bar; A second portion wrapped around the reinforcing bar; a joint portion that joins the first portion and the second portion with their axes perpendicular to each other; The entirety of the binding wire is loosely wound so that the main bars and the reinforcing bars can be spaced apart in the axial direction of the main bars.

[0015] With this structure, the reinforcing bar cage, which is assembled in advance at the factory by wrapping the main bars with reinforcing bars, can be folded as a whole without changing the positional relationship of the reinforcing bars to the main bars. This makes transportation easier and enables efficient assembly and work of the reinforcing bars. Effect of the Invention

[0016] According to the reinforcing bar or the connecting method of the present invention, the elastic restoring force of the reinforcing bar acts on both ends of the reinforcing bar in the direction of slipping out of the connecting member. As a result, the male and female threads are in contact with each other with a certain force, and the connecting member is fixed to both ends of the reinforcing bar, so that the necessary tensile strength and rigidity can be secured without using lock nuts. Therefore, the labor required to connect the reinforcing bar to the connecting member can be reduced, and it is possible to use inexpensive reinforcing bar joints with low performance such as class B or class C.

[0017] The main bars of the present invention can achieve the same performance as main bars connected by lap joints, which can save resources. In addition, since there is no need to process female threads in the connecting members, costs can be reduced. Furthermore, the reinforcing bar structure of the present invention makes it easy to transport the reinforcing bars. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a front view showing a bent reinforcing bar according to the first embodiment of the present invention. [Diagram 2] FIG. 4 is a front view showing connected reinforcing bars according to the embodiment. [Diagram 3] FIG. 4 is a vertical cross-sectional view of a connecting member according to the embodiment. [Figure 4] 4 is an enlarged view of a connecting portion between the connecting member and the reinforcing bar. FIG. [Diagram 5] FIG. 6 is a vertical cross-sectional view of a connecting member according to a second embodiment of the present invention. [Figure 6] FIG. 2 is a vertical cross-sectional view showing a method of supporting the reinforcing steel structure of the present invention within a formwork. [Figure 7] A vertical cross-sectional view showing an example of a procedure for screwing a reinforcing bar body into a connecting member. [Figure 8] FIG. 13 is a front view showing a bent reinforcing bar according to a third embodiment of the present invention. [Figure 9A] FIG. 10 is a vertical cross-sectional view of a connecting member according to a fourth embodiment of the present invention. [Figure 9B] FIG. 11 is a longitudinal cross-sectional view showing a modified example of the muscle body according to the same embodiment. [Figure 10A] FIG. 2 is a front view showing a binding wire wound around the main reinforcement and reinforcing bar of the present invention. [Figure 10B] FIG. 2 is a perspective view showing a binding wire wound around the main reinforcement and reinforcing bar of the present invention. [Figure 11] FIG. 2 is a perspective view showing the state before folding of the steel structure of the present invention. [Figure 12] FIG. 2 is a perspective view showing the reinforcing steel structure of the present invention in a folded state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] [First embodiment] A first embodiment of the present invention will be described with reference to FIGS. As shown in Fig. 1, this reinforcing bar 10 is a shear reinforcement bar that surrounds multiple main bars 1 from the outside, and its reinforcing bar body 12 is made of a rod material with a diameter of D10 to D13, D16 mm made of a general reinforcing bar material having elasticity (e.g., SD345, SD390, SD490, high-strength shear reinforcement bar, etc.), bent into an approximately rectangular shape, and has a large first connection gap 20 in the middle in a natural state. As shown in Fig. 3, when the male threads 12c of both ends 12a, 12b of the reinforcing bar body 12 are relatively long, a connecting member (coupler) 14 is screwed into one end 12a of the opposing both ends 12a, 12b of the reinforcing bar body 12, and the reinforcing bar body 12 is elastically deformed by an external force so that both ends 12a, 12b approach each other, and the other end 12b of the reinforcing bar body 12 is screwed into the connecting member 14, and the two ends 12a, 12b face each other with a second connection gap 21 smaller than the first connection gap 20. In this manner, both ends 12a, 12b of the muscle body 12 are screw-connected by the connecting member 14, and in this connected state, the elastic restoring forces F1, F2 of the muscle body 12 cause the threads of the male threads 12c of both ends 12a, 12b to contact the threads of the female threads 14c of the connecting member 14 with a constant force in the direction in which both ends 12a, 12b slip out of the connecting member 14. The muscle body 12 may be a deformed reinforcing bar with ribs 40 and nodes 41 formed on the outer surface of the reinforcing bar shaft as shown in Figures 9A and 9B.

[0020] In order to ensure the above-mentioned connection between the connecting member 14 and the reinforcing bar 10, a part of the contact portion between the connecting member 14 and the reinforcing bar body 12 may be joined by crimping in the radial direction by pressing from the radially outward. This keeps the female thread 14c of the connecting member 14 in contact with the male threads 12c of both ends 12a, 12b, and keeps the tensile forces F1, F2 acting on them, thereby ensuring the performance required for the reinforcing bar 10. This series of operations is generally carried out in a factory. After cutting the material to the required length, threads are machined on both ends, and the material is bent into a specified rectangle, couplers are attached, and the material is then machined and crimped. These processes are carried out on an assembly line.

[0021] Figure 4 shows one end 12a of the bar body 12 in contact with the female thread 14c of the connecting member 14. Similarly, the other end 12b of the bar body 12 is in contact with the female thread 14c of the connecting member 14 with a constant force by F2 (Figure 3) in the direction of coming out of the connecting member 14. As a result, the required performance of the reinforcing bar 10 can be ensured without using a lock nut.

[0022] [Second embodiment] As shown in Fig. 5, when the male thread 12c at one end 12a of the reinforcing bar 12 is short and the male thread 12c at the other end 12b is long, a connecting member 14 is attached to the male thread 12c at the other end 12b of the reinforcing bar 12 in advance, and the connecting member 14 is screwed into the one end 12a of the reinforcing bar 12 to connect the two ends 12a, 12b. Then, the one end 14a of the connecting member 14, which is the short thread side, is firmly screwed into the incomplete thread portion 12ca of the one end 12a of the reinforcing bar 12 to lock it. By locking it in this way, the required performance of the reinforcing bar 10 can be ensured without using a lock nut, even for the other end 12b on the long thread side, which cannot be locked using the incomplete thread portion 12ca.

[0023] In beams, the method of placing the reinforcing bars 10 by supporting the upper end bars 1A is common. However, in the reinforcing bars of the present invention connected by connecting members 14, as shown in Fig. 6, it is preferable that the weight of the lower end bars 1B is supported by the connecting members 14 by supporting the middle bars 1C by the suspension wires 25 in the space inside the formwork 30 during concrete pouring. Both ends of the suspension wires 25 are fixed to the formwork 30 by, for example, pins 27. This applies an additional force to the female threads 14c of the connecting members 14 in the direction of coming out of the connecting members 14 by the weight of the lower end bars 1B, improving the effect of ensuring the tensile strength and rigidity required for the reinforcing bars 10.

[0024] The male thread 12c of the muscle body 12 shown in Figures 3 to 5 is a rolled thread, and due to work hardening (also called plastic hardening), at least the surface layer is harder than other parts of the muscle body 12.

[0025] The length of the male screw 12c only needs to be the necessary screwing length for the coupler 14, but as shown in FIG. 7, it is set to a length L that allows the entire coupler 14 to be screwed in. In this way, when connecting both ends 12a, 12b of the muscle body 12, the entire coupler 14 is screwed into the male screw 12c of the other end 12b, and the coupler 14 is unscrewed and moved to the left in FIG. 7 with the end faces of the muscle body 12 aligned or close to each other, and then screwed into the male screw 12c of one end 12a, resulting in the connection state shown in FIG. 3 to FIG. 5. Therefore, there is no need to pull both ends 12a, 12b of the muscle body 12 while screwing them in, improving the workability of on-site connection. The cross-sectional shape of the thread groove of the male screw 12c may be triangular or trapezoidal.

[0026] With this type of reinforcing bar joint, the reinforcing bar 10 can be connected by screwing the male threads 12c, 12c of the bar body 12 into the coupler 14, and as with general reinforcing bar joints, this simplifies reinforcement arrangement and shortens construction time.

[0027] [Third embodiment] A fourth embodiment of the present invention will be described with reference to FIG. As shown in Figure 8, this reinforcing bar 10 has the same configuration as the first embodiment, except that the reinforcing bar body 12 is connected midway by another connecting member (coupler) 15. This allows the reinforcing bar body 12 to easily deform elastically so that both ends 12a, 12b of the reinforcing bar body 12 approach each other without requiring a large external force, even when the reinforcing bar body 12 is wound around the main reinforcing bar of a large column or beam, which makes the reinforcing bar body 12 long. It is preferable to provide a lock nut for this other connecting member (coupler) 15 installed midway to eliminate rattling.

[0028] [Fourth embodiment] As shown in FIG. 9A, the threads of the male threads 2c at both ends 2a, 2b of the main bar 2 of the main bar 1 may be inserted into a round tube connecting member 16 without female thread processing, and the connecting member 16 and the threads of the male threads 2c may be connected by radial crimping. This allows the same performance as the main bar 1 connected by a lap joint to be achieved without female thread processing on the connecting member 16. In addition, since the connecting member 16 does not require female thread processing, costs can be reduced. Although FIGS. 9A and 9B show a case where the nodes of the deformed bar are bamboo nodes, they may be threaded nodes. The main bar 1 is a deformed bar with ribs 40 and nodes 41 formed on the outer periphery, but a main bar consisting of a normal rebar shaft may be used. This connecting method may also be used for reinforcing bars.

[0029] A large amount of thin rebar is used for the main reinforcement of small foundations for houses, etc., and the joints are lap joints. The length of these overlaps is enormous on a national level, which is a waste of resources. Since the shape of rebar using the crimping method does not need to be closed, adopting this crimping method can help conserve resources.

[0030] When the bar body 2 is a deformed bar, the incomplete thread portion 2ca is missing a rib due to preliminary cutting beforehand for thread rolling. Therefore, the cross-sectional area is reduced compared to the non-missing portion, and the tensile strength is lower than that of the non-missing portion. Therefore, if the length of the connecting member 16 is set so that the incomplete thread portions 2ca, 2ca are all inside the connecting member 16, the tensile strength will be equivalent to that of the non-missing portion. It is preferable to determine whether the length of the connecting member 16 is set so that the incomplete thread portions 2ca, 2ca are all inside the connecting member 16, or so that the incomplete thread portions 2ca, 2ca are outside the connecting member 16, depending on the performance required for the joint portion.

[0031] The male thread 12c of the main bar 12 in the first to fourth embodiments is a helical thread, but the male thread 2c in the fifth embodiment may be a so-called parallel thread 2d in which annular protrusions are provided at equal intervals in the axial direction, as shown in Fig. 9B. The parallel thread method has no incomplete threads and is entirely complete. Therefore, compared to the case where a helical thread is used, the reinforcing performance required for the main bar 1 can be ensured even if a connecting member 16 with a shorter length is used.

[0032] In the case of Fig. 9B, the rib cross-section missing portion 42 is entirely inside the connecting member 16. In this way, by overlapping the connecting member 16 with the rib cross-section missing portion 42, not only the performance required for the joint portion but also the performance required for the muscle body 12 can be secured.

[0033] Incidentally, when assembling reinforcing bars at a construction site, the reinforcing bars must be distributed to the location where they are to be installed, with some of them having been previously bent at a processing plant. On the other hand, if these parts are assembled in advance and only installed at the site, a large volume of material must be transported along the way, resulting in a lot of waste. Therefore, efficient transportation can be achieved by adopting a method in which a reinforcing bar cage preassembled at a factory using main bars and reinforcing bars is folded. This method is called the bellows method. One example of this bellows method is disclosed in Patent No. 3839963, but it has the disadvantage of being costly because it is necessary to provide an elastic member for each binding wire.

[0034] In the bellows method, the tie wire 28A on the main reinforcement side is wound tightly in one turn, and the tie wire 28B on the shear reinforcement side is wound loosely in one turn. As shown in Fig. 11, when folding, the beam is placed horizontally, and for example, the upper end reinforcement 1A is pushed and moved in the longitudinal direction to fold (Fig. 12). As shown in Figs. 10A and 10B, if the tie wire 28A wound around the main reinforcement 1 side and the tie wire 28B wound around the reinforcement 10 side are perpendicular to each other at the joint 29, when the assembled reinforcing bar cage is folded, the cage can be folded as a whole without changing the positional relationship between the main reinforcement 1 and the tie wire 28A, and the positional relationship between the reinforcement 10 and the tie wire 28B. However, due to construction errors, etc., not all shear reinforcements may be positioned at right angles to the main reinforcements, and so when folded in this manner, the axis of rotation (the axis of the upper reinforcement 10 in Fig. 11) may not be aligned with the entire upper reinforcement. Therefore, by loosely fastening the tie wires 28A and 28B, the reinforcement body 12 can move within the clearance with the tie wire 28A, allowing a certain degree of misalignment of the rotation axis. The tie wires 28A and 28B are twisted 90° with a tool such as a hacksaw at the intersection of the main reinforcement 1 and the reinforcement 10 to make them perpendicular. In this way, the bulk of the reinforcement structure having the main reinforcement 1 and the reinforcing bars 10 is reduced, and then it is transported to the site and installed. After installation is complete, the main reinforcement and the shear reinforcement are securely tied together to complete the assembly. In this way, according to the tying method of the present invention, there is no need to use any other members than the tie wire, such as elastic members, and therefore costs can be reduced. In addition, in Figures 11 and 12, for simplification, only the upper end muscle 1A and the lower end muscle 1B are shown.

[0035] Although the embodiment of the present invention has been described above, the disclosed embodiment is illustrative in all respects and is not restrictive. For example, the muscle body 12 may be bent into a rectangular, circular or elliptical shape. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0036] 1...Reinforcing bars (main bars) 1A...Upper extremity muscle 1B…Lower end reinforcement 1C...Intermediate muscle 2...Muscle body 2a, 2b...ends 2c…Male thread 2d…Parallel thread 10…Reinforcement bar 12...Muscle body 12a, 12b...ends 12c...Male thread 14, 15, 16...Connecting members (couplers) 20…First connecting gap 21...Second connecting gap 25…Suspension wire 27…Pin 28A, 28B… Binding wire 29…Joint 30…Formwork 40…Rib Section 41... 42…Rib cross section defect

Claims

1. A reinforcing bar that surrounds a plurality of main reinforcements from the outer periphery, The muscle body has a closed shape and has a first connection gap in the middle in a natural state, A reinforcing bar in which both ends of the bar body are threadedly connected by a connecting member while the both ends are elastically deformed by an external force so that they approach each other and face each other with a second connecting gap which is smaller than the first connecting gap, and in the connected state, the elastic restoring force of the bar body causes the male threads of the both ends to contact the female threads of the connecting member in the direction in which the both ends come out of the connecting member.

2. When surrounding multiple main bars with reinforcing bars from the periphery, The muscle body is bent into a closed shape, and a first connecting gap is provided in the middle in the natural state; A method of connecting reinforcing bars in which the muscle body is elastically deformed by an external force so that both ends approach each other and face each other with a second connecting gap that is smaller than the first connecting gap, and then both ends of the muscle body are screwed together using a connecting member, and in this connected state, the elastic restoring force of the muscle body brings the male threads of the both ends into contact with the female threads of the connecting member in the direction in which the both ends come out of the connecting member.

3. A plurality of muscle bodies each having a male thread formed at at least one end thereof; a connecting member having an insertion hole into which the male screw is inserted from both ends, The threads of the male screw are inserted into the insertion hole of the connecting member, A main bar in which the connecting member and the thread are joined by radial crimping.

4. A steel structure in which the outer periphery of a plurality of parallel-arranged main reinforcements is surrounded by the reinforcing bar according to claim 1, and the intersections of the main reinforcements and the reinforcing bars are tied together by a tie wire, A first portion of the binding wire wound around the main reinforcing bar; A second portion wrapped around the reinforcing bar; a joint portion that joins the first portion and the second portion with their axes perpendicular to each other, A reinforced concrete structure in which the entirety of the tie wire is loosely wound around the main bars and the reinforcing bars so that they can be spaced apart in the axial direction of the main bars.

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