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

Abstract

According to the present invention, a bar body of a reinforcing bar (10) has a closed shape, and the reinforcing bar (10) has a first joining gap (20) at the middle thereof in a natural state. By screwing male screws (12c) of both end portions (12a, 12b) of the bar body (12) into female screws (14c) of a joining member (14) in a state in which said both 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), 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.

Description

Reinforcing bars connected to main bars and connecting method of reinforcing bars Related Applications

[0001] This application claims priority to Japanese Patent Application No. 2023-136598, filed August 24, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a reinforcing bar connected to the main reinforcement of a column or beam in reinforced concrete, and a method for connecting the reinforcing bar.

[0003] Conventionally, when constructing concrete beams and columns, reinforcing bars are attached to the outer periphery of the main reinforcement bars to improve their strength. In this case, the reinforcing bars are wrapped around the main reinforcement bars and attached to the main reinforcement bars by welding their ends together or by hooking them onto the main reinforcement bars. However, welding methods do not provide consistent quality and require high-performance joints for welding, which increases costs. The method of hooking the reinforcing bars onto the main reinforcement bars makes the reinforcing bar arrangement structure complicated and makes on-site work difficult.

[0004] It has been proposed to use threaded reinforcing bar joints to connect main reinforcing bars, which can simplify the reinforcing bar arrangement and shorten the construction period (see, for example, Patent Document 1). This proposal also suggests providing a lock nut to eliminate rattle.

[0005] The performance standards for reinforcing bar splices set by the government are divided into four levels: SA, A, B, and C. While SA or A grades are permitted for main reinforcement, B and C grade reinforcing bar splices are also permitted for reinforcing bars. While SA and A grade reinforcing bar splices have a set allowable slippage when stress is applied, B and C grade reinforcing bar splices do not. Therefore, when reinforcing bars meet the standard strength, rigidity, etc., using B and C grade reinforcing bar splices has the advantage of avoiding costs and excessive quality requirements.

[0006] Patent No. 5869716

[0007] The use of the threaded reinforcing bar joints as reinforcing bars is expected to simplify the arrangement of reinforcement bars and shorten the construction period. However, in order to achieve the required performance, it is necessary to provide a lock nut or use an SA or A class reinforcing bar joint. Therefore, when a lock nut is provided, there is a problem that additional labor is required to tighten the lock nut to the required torque compared to when a lock nut is not provided. When a lock nut is not provided, it is difficult to achieve a high-performance reinforcing bar joint such as an SA or A class, and costs increase due to the need to increase the thread precision of the reinforcing bar joint.

[0008] An object of the present invention is to enable easy attachment of closed-shaped reinforcing bars to main bars, thereby reducing the number of steps and costs required to connect the reinforcing bars to connecting members.

[0009] The reinforcing bar of the present invention is a reinforcing bar that surrounds multiple main bars from the outside, and has a closed shape as the bar body, and in its natural state has a first connecting gap in the middle, and 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. Both ends of the bar body are screw-connected by connecting members, 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 members in a direction that causes the both ends to come out of the connecting members.

[0010] According to this configuration, male threads are formed at both ends of the reinforcing bar body, which has a first connecting gap. An external force is applied in the direction of closing the reinforcing bar body, 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 unscrewing from the connecting member. As a result, the male and female threads are in contact with each other with a constant force, and the connecting member is fixed to both ends of the reinforcing bar body. This ensures the necessary tensile strength and rigidity for the reinforcing bar without the use of lock nuts. This reduces the labor required to connect the reinforcing bar body to the connecting member. Furthermore, 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. A closed shape refers to a shape that forms a single enclosed area, such as a rectangle, circle, or ellipse.

[0011] The method of connecting reinforcing bars of the present invention involves, when surrounding multiple main bars from the outer periphery with reinforcing bars, bending the reinforcing bar body into a closed shape, leaving a first connecting gap midway in the natural state, elastically deforming the reinforcing bar body using an external force so that both ends thereof approach each other, and then screw-connecting both ends of the reinforcing bar body using a connecting member in a state where they face each other with a second connecting gap smaller than the first connecting gap, and in this connected state, the elastic restoring force of the reinforcing 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.

[0012] According to this method, male threads are formed at both ends of the reinforcing bar body, which has a first connecting gap. An external force is applied in the direction of closing the reinforcing bar body, 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 pulling out of the connecting member. As a result, the male and female threads contact with each other with a constant force, securing the connecting member to both ends of the reinforcing bar body. This ensures the required performance of the reinforcing bar without the use of lock nuts. This reduces the labor required to connect the reinforcing bar body to the connecting member. Furthermore, since excessive performance is not required, it is possible to use inexpensive reinforcing bar joints, such as Class B or Class C joints.

[0013] The main reinforcement of the present invention comprises a plurality of reinforcement bodies each having a male thread formed at at least one end thereof, and connecting members each having an insertion hole into which the male threads are inserted from both ends, the threads of the male threads being inserted into the insertion holes of the connecting members, and the connecting members and the threads being joined by radial crimping.

[0014] This configuration can achieve the same performance as main reinforcement bars connected by lap joints, thereby saving resources. Also, since there is no need to process female threads in the connecting members, costs can be reduced.

[0015] A steel reinforcement structure using the reinforcing bars of the present invention has the reinforcing bars of the present invention surrounding the outer periphery of a plurality of parallel-arranged main reinforcements, and the intersections of the main reinforcements and the reinforcing bars are tied together with tie wires, the tie wire having a first portion wound around the main reinforcements, a second portion wound around the reinforcing bars, and a joint portion that joins the first portion and the second portion with their axes perpendicular to each other, and the entire tie wire is loosely wound so that the main reinforcements and the reinforcing bars can be separated in the axial direction of the main reinforcements.

[0016] This structure allows the rebar cage, which is assembled in advance at the factory by surrounding the main reinforcement bars with reinforcing bars, to be folded as a whole without changing the positional relationship of the reinforcing bars to the main reinforcement bars, making transportation easier and enabling efficient assembly and work of reinforcing bars.

[0017] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

[0018] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present invention. The scope of the present invention is defined by the appended claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same or corresponding parts.

[0023] Figure 1 is a front view showing bent reinforcing bars according to a first embodiment of the present invention.

[0024] Figure 2 is a front view showing connected reinforcing bars according to the same embodiment.

[0025] Figure 3 is a longitudinal sectional view of a connecting member according to the same embodiment.

[0026] Figure 4 is an enlarged view of a connection portion of the connecting member with the reinforcing bars.

[0027] Figure 5 is a longitudinal sectional view of a connecting member according to a second embodiment of the present invention.

[0028] Figure 6 is a longitudinal sectional view showing a method of supporting a steel structure of the present invention within a formwork.

[0029] Figure 7 is a longitudinal sectional view showing an example of a procedure for screwing a reinforcing bar body into a connecting member.

[0029] Figure 8 is a front view showing bent reinforcing bars according to a third embodiment of the present invention.

[0029] Figure 9 is a longitudinal sectional view of a connecting member according to a fourth embodiment of the present invention.

[0030] Figure 10 is a longitudinal sectional view showing a modified reinforcing bar body according to the same embodiment.

[0031] Figure 11 is a front view showing main reinforcing bars and binding wires wound around the reinforcing bars according to the present invention.

[0032] Figure 12 is a perspective view showing main reinforcing bars and binding wires wound around the reinforcing bars according to the present invention.

[0033] Figure 13 is a perspective view showing a steel structure of the present invention in a state before folding. FIG. 2 is a perspective view showing the reinforcing steel structure of the present invention in a folded state.

[0019] [First embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 4. As shown in Figure 1, this reinforcing bar 10 is a shear reinforcement bar that surrounds the outer periphery of multiple main reinforcements 1, and its reinforcing bar body 12 is made of a rod material with a diameter of D10 to D13, or D16 mm and made of a general reinforcing bar material with elasticity (e.g., SD345, SD390, SD490, high-strength shear reinforcement, etc.), bent into a roughly rectangular shape, and has a large first connecting gap 20 in the middle in its natural state. 3, when the male threads 12c at both ends 12a, 12b of the muscle body 12 are relatively long, a connecting member (coupler) 14 is screwed into one end 12a of the opposing ends 12a, 12b of the muscle body 12, and an external force is used to elastically deform the muscle body 12 so that both ends 12a, 12b approach each other, and the other end 12b of the muscle body 12 is screwed into the connecting member 14, facing each other across a second connecting gap 21 that is smaller than the first connecting gap 20. In this way, both ends 12a, 12b of the muscle body 12 are threadedly 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 at 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 are removed from the connecting member 14. The bar body 12 may be a deformed bar having ribs 40 and nodes 41 formed on the outer surface of the bar shaft, as shown in Figures 9A and 9B.

[0020] To further secure the connection between the connecting member 14 and the reinforcing bar 10, a portion of the contact area between the connecting member 14 and the reinforcing bar body 12 may be joined by crimping radially by pressing from the outside in the radial direction. This maintains contact between the female threads 14c of the connecting member 14 and the male threads 12c of both end portions 12a, 12b, and maintains the application of tensile forces F1, F2, thereby ensuring the required performance of the reinforcing bar 10. This series of operations is generally performed 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, etc., couplers are attached, processed, and crimped. These processes are carried out in an assembly line.

[0021] Figure 4 shows one end 12a of the reinforcing bar 12 in contact with the female thread 14c of the connecting member 14. Similarly, the other end 12b of the reinforcing bar 12 is in contact with the female thread 14c of the connecting member 14 with a constant force due to 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 Figure 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 first attached to the male thread 12c at the other end 12b of the reinforcing bar 12, and the connecting member 14 is then screwed into the end 12a of the reinforcing bar 12 to connect the two ends 12a, 12b. The end 14a of the connecting member 14, which is the short-threaded end, is then firmly screwed into the incomplete threaded portion 12ca of the end 12a of the reinforcing bar 12 to lock it in place. 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 of the reinforcing bar 12, which is the long-threaded end, and cannot be locked using the incomplete threaded portion 12ca.

[0023] In beams, the placement of reinforcing bars 10 is generally performed by supporting the upper end reinforcing bars 1A. However, in the case of reinforcing bars of the present invention connected by connecting members 14, as shown in Figure 6, it is preferable that the weight of the lower end reinforcing bars 1B is supported by the connecting members 14 by the suspension wires 25 in the space within 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 slipping out of the connecting members 14, by the weight of the lower end reinforcing bars 1B, thereby improving the effect of ensuring the necessary tensile strength and rigidity 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), the hardness of at least the surface layer is harder than other parts of the muscle body 12.

[0025] The length of the male thread 12c need only be the required threading length for the coupler 14, but as shown in Figure 7, it is set to a length L that allows the entire coupler 14 to be screwed in. This allows the entire coupler 14 to be screwed into the male thread 12c of the other end 12b when connecting the two ends 12a and 12b of the muscle body 12. Then, with the end faces of the muscle body 12 aligned or close together, the coupler 14 is unscrewed and moved to the left in Figure 7 to thread into the male thread 12c of one end 12a, achieving the connection state shown in Figures 3 to 5. This eliminates the need to pull the two ends 12a and 12b of the muscle body 12 while screwing them in, improving the workability of on-site connection. The cross-sectional shape of the male thread 12c groove 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 reinforcing 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 Figure 8. 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 a separate 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 wrapped around the main reinforcing bars of a large column or beam where the reinforcing bar body 12 is long. It is preferable to provide a lock nut on this separate connecting member (coupler) 15 to eliminate rattle.

[0028] [Fourth Embodiment] As shown in Figure 9A, the threads of the male threads 2c on both ends 2a, 2b of the main reinforcing bar 2 of the main reinforcing bar 1 may be inserted into a round-tube connecting member 16 without internal threading, and the connecting member 16 and the threads of the male threads 2c may be connected by radial crimping. This allows the connecting member 16 to exhibit performance equivalent to that of a main reinforcing bar 1 connected by a lap joint, without internal threading. Furthermore, since the connecting member 16 does not require internal threading, costs can be reduced. While Figures 9A and 9B show a case in which the deformed reinforcing bar has a bamboo-shaped knot, a threaded knot may also be used. The main reinforcing bar 1 is a deformed reinforcing bar with a rib 40 and a knot 41 formed on the outer periphery, a main reinforcing bar consisting of a standard reinforcing bar shaft may also be used. This connecting method may also be used for reinforcing bars.

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

[0030] When the reinforcing bar body 2 is a deformed reinforcing bar, the incomplete thread portion 2ca is missing a rib due to preliminary machining for the rolled thread. 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 adjusted 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 the length of the connecting member 16 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 based on the performance required for the joint.

[0031] In the first to fourth embodiments, the male thread 12c of the main reinforcing bar 12 is a helical thread, but in the fifth embodiment, the male thread 2c may be a so-called parallel thread 2d, in which annular protrusions are provided at equal intervals in the axial direction, as shown in Figure 9B. The parallel thread method does not have incomplete threads, and all threads are complete. Therefore, compared to when a helical thread is used, the reinforcing performance required for the main reinforcing bar 1 can be ensured even if a connecting member 16 with a shorter length is used.

[0032] In the case of Figure 9B, the rib cross-sectional defect 42 is entirely inside the connecting member 16. By overlapping the connecting member 16 with the rib cross-sectional defect 42 in this way, it is possible to ensure not only the performance required for the joint portion but also the performance required for the muscle body 12.

[0033] Incidentally, when assembling rebar at a construction site, the rebar must be distributed to the installation location, with some of the rebar having been previously bent or processed at a processing plant. On the other hand, if these components are pre-assembled and then simply installed at the site, a large volume of material must be transported along the way, resulting in a lot of waste. Therefore, adopting a method in which a rebar cage pre-assembled at a factory using main reinforcement and reinforcing bars is folded up enables efficient transportation. This method is called the accordion method. An example of this accordion method is disclosed in Patent No. 3839963, but it has the disadvantage of being costly because it requires the installation of an elastic member in each binding wire.

[0034] In the accordion construction method, the binding wire 28A on the main reinforcement side is tightly wound once, and the binding wire 28B on the shear reinforcement side is loosely wound once. As shown in Figure 11, when folding, the beam is placed horizontally and folded by, for example, pushing and moving the upper end reinforcement 1A in the longitudinal direction (Figure 12). As shown in Figures 10A and 10B, if the binding wire 28A wound around the main reinforcement 1 side and the binding wire 28B wound around the reinforcing bar 10 side are perpendicular at the joint 29, the assembled reinforcing bar cage can be folded as a whole without changing the positional relationship between the main reinforcement 1 and the binding wire 28A, and the positional relationship between the reinforcing bar 10 and the binding wire 28B. However, due to construction errors and other factors, not all shear reinforcement bars may be positioned perpendicular to the main reinforcement bars. Therefore, folding in this manner may result in the rotation axis (in Figure 11, the axis of the uppermost reinforcement bar 10) not being aligned with the entire upper reinforcement bar. Therefore, by loosely fastening the tie wires 28A and 28B, the reinforcing bar body 12 can move within the clearance between the tie wire 28A and the main reinforcement bar 10, allowing for a certain degree of misalignment of the rotation axis. The tie wires 28A and 28B are twisted 90° at the intersections of the main reinforcement bars 1 and the reinforcing bar 10 to make them orthogonal. The reinforcing bar structure, consisting of the main reinforcement bars 1 and the reinforcing bar 10, is then transported to the construction site and installed after its volume is reduced. After installation, the main reinforcement bars and the shear reinforcement bars are securely fastened to complete the assembly. Thus, the fastening method of the present invention eliminates the need for components other than tie wires, such as elastic members, thereby reducing costs. For the sake of simplicity, only the upper end streaks 1A and the lower end streaks 1B are shown in Figures 11 and 12.

[0035] While the above describes the mode for carrying out the present invention based on the embodiments, the disclosed embodiments are illustrative in all respects and are not limiting. For example, the muscle body 12 may be bent into a rectangular, circular, or elliptical shape. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0036] As described above, the preferred embodiment has been described with reference to the drawings, but various additions, modifications, and deletions can be made without departing from the spirit of the present invention. Therefore, such additions, modifications, and deletions are also included in the scope of the present invention.

[0037] DESCRIPTION OF SYMBOLS 1...Reinforcing bar (main bar) 1A...Upper end bar 1B...Lower end bar 1C...Intermediate bar 2...Bar body 2a, 2b...End part 2c...Male thread 2d...Parallel thread 10...Reinforcing bar 12...Bar body 12a, 12b...End part 12c...Male thread 14, 15, 16...Connecting member (coupler) 20...First connecting gap 21...Second connecting gap 25...Suspension wire 27...Pin 28A, 28B...Binding wire 29...Joint 30...Formwork 40...Rib 41...Section 42...Rib cross-section missing part

Claims

1. A reinforcing bar that surrounds multiple main bars from the outside, wherein the bar body has a closed shape and has a first connecting gap in the middle in its natural state, and both ends of the bar body are elastically deformed by an external force so that they approach each other and face each other with a second connecting gap that is smaller than the first connecting gap. Both ends of the bar body are screw-connected by connecting members, 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 members in the direction in which the both ends are pulled out of the connecting members.

2. A method of connecting reinforcing bars in which, when surrounding multiple main bars with reinforcing bars from the outside, the reinforcing bar body is bent into a closed shape, leaving a first connecting gap halfway in the natural state, and an external force is used to elastically deform the reinforcing bar body so that both ends approach each other and face each other with a second connecting gap smaller than the first connecting gap. Then, both ends of the reinforcing bar body are screwed together using a connecting member, and in this connected state, the elastic restoring force of the reinforcing bar 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 main reinforcement comprising a plurality of reinforcing bar bodies each having a male thread formed at least at one end thereof, and connecting members each having an insertion hole into which the male thread is inserted from both ends, the threads of the male threads being inserted into the insertion holes of the connecting members, and the connecting members and the threads being joined by radial crimping.

4. A reinforced concrete structure in which the outer periphery of a number of main reinforcements arranged in parallel is surrounded by the reinforcing bars as described in claim 1 and the intersections of the main reinforcements and the reinforcing bars are tied with tie wires, wherein the tie wire has a first portion wound around the main reinforcements, a second portion wound around the reinforcing bars, and a joint portion that joins the first portion and the second portion with their axes perpendicular to each other, and the entire tie wire is wound loosely so that the main reinforcements and the reinforcing bars can be separated in the axial direction of the main reinforcements.

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