Reinforcement bar connected to main bar and method of connecting reinforcement bar

Abstract

is subjected to an elastic force in a direction that causes the elastic restoring force of the bar body

Description

[Technical Field]

[0001] This application claims priority to Japanese Patent Application No. 2023-136598 filed on August 24, 2023, and incorporates it in its entirety as part of this application.

[0002] This invention relates to reinforcing bars in reinforced concrete that are connected to the main reinforcement bars of columns or beams, and the connection method thereof. [Previous Technology]

[0003] In the past, when constructing beams or columns in concrete structures, reinforcing bars were installed around the main reinforcing bars to increase strength. This process involved winding the reinforcing bars around the main reinforcing bars and welding or tying the ends of the reinforcing bars to each other. However, the welding method suffers from inconsistent quality, and the need for high-performance joints during welding is a major cause of increased costs. Tying the reinforcing bars to the main reinforcing bars results in complex reinforcement configurations and poor on-site operability.

[0004] As a method for connecting main reinforcing bars, it is proposed to simplify the reinforcement configuration or shorten the construction period by using threaded steel bar joints (e.g., Patent Document 1). In the example proposed here, it is also proposed to eliminate loosening by setting anti-loosening nuts.

[0005] The performance evaluation criteria for steel bar splices stipulated in Japan are divided into four levels: SA, A, B, and C. SA or A grade splices are permitted for main reinforcement bars, while B and C grade splices are permitted for reinforcing bars. SA and A grade splices have permissible slippage under stress, while B and C grade splices do not have specified slippage. Therefore, for reinforcing bars, using B and C grade splices offers advantages in avoiding increased costs and excessive quality requirements, provided that the strength and rigidity requirements of the standards are met. [Prior Art Documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent No. 5869716 [Summary of the Invention]

[0007] [The problem the invention aims to solve]

[0008] It is hoped that by using this threaded rebar splice for reinforcement, the rebar configuration can be simplified and the construction period shortened. However, in order to meet the specified performance, it is necessary to install lock nuts or use SA or A grade rebar splices. Therefore, compared with the case where lock nuts are not installed, there are additional costs and time issues such as tightening lock nuts to a specified torque. Without lock nuts, it is difficult to achieve high-performance rebar splices such as SA or A grade, thus increasing the cost of improving the thread accuracy of the rebar splice.

[0009] The object of this invention is to enable the easy installation of closed-shaped reinforcing bars onto the main reinforcing bars, and to reduce the time and cost of connecting the reinforcing bars to structural members. [Technical Means for Solving the Problem]

[0010] The reinforcing rib of the present invention is a reinforcing rib in which a plurality of main ribs are wound around the outer periphery. The rib body is closed in shape and is given a first connection gap in the middle in the natural state. When the rib body is elastically deformed by external force so that the two ends of the rib body are close to each other and the two ends face each other with a second connection gap smaller than the first connection gap, the two ends of the rib body are connected by a connecting member in a threaded manner. In the connected state, due to the elastic restoring force of the rib body, the thread of the external thread of the two ends contacts the thread of the internal thread of the connecting member in the direction in which the two ends are disengaged from the connecting member.

[0011] According to this configuration, external threads are formed at both ends of the reinforcing bar body having a first connection gap, and an external force is applied in the direction of closing the reinforcing bar body, locking it into the internal thread of the connecting member. Thereby, at each end of the reinforcing bar body, the elastic restoring force acts in the direction of disengagement from the connecting member. As a result, the external thread and the internal thread are in contact with a fixed force. Therefore, since the connecting member is fixed to both ends of the reinforcing bar body, the required tensile strength or rigidity for the reinforcing bar can be ensured without using anti-loosening nuts. Thus, the time spent connecting the reinforcing bar body to the connecting member can be reduced. Furthermore, since excessive performance is not required, inexpensive reinforcing bar joints with low tensile strength, such as Grade B or Grade C, can be used. In addition, the so-called closed shape is a rectangle, circle, ellipse, etc., forming a closed area.

[0012] The method for connecting the reinforcing ribs of the present invention involves bending the rib body into a closed shape when using the reinforcing ribs to wrap around a plurality of main ribs from the outer periphery, and in a natural state, providing a first connection gap in the middle, and in a state where the rib body is elastically deformed by external force so that its two ends approach each other, and the two ends face each other with a second connection gap smaller than the first connection gap, the two ends of the rib body are connected by a connecting member in a threaded manner, and in this connection state, due to the elastic restoring force of the rib body, the threads of the external threads of the two ends contact the threads of the internal threads of the connecting member in the direction in which the two ends disengage from the connecting member.

[0013] According to this method, external threads are formed at both ends of the reinforcing bar body having a first connection gap, and an external force is applied in the direction of closing the reinforcing bar body, locking it into the internal threads of the connecting member. Thereby, at each end of the reinforcing bar body, the elastic restoring force acts in the direction of disengagement from the connecting member. As a result, the external threads and internal threads are in contact with a fixed force, thereby ensuring the required performance for the reinforcing bar is achieved without using lock nuts, since the connecting member is fixed to both ends of the reinforcing bar body. Therefore, the time spent connecting the reinforcing bar body to the connecting member can be reduced, and furthermore, since excessive performance is not required, inexpensive reinforcing bar connectors such as Grade B or Grade C can be used.

[0014] The main rib of the present invention comprises: a plurality of rib bodies, each having an external thread formed at at least one end; and a connecting member having an insertion hole into which the external thread can be inserted from both ends; inserting the thread as the external thread into the insertion hole of the connecting member; and joining the connecting member and the thread by means of a radially converging joint.

[0015] Based on this configuration, since it can achieve the same performance as the main reinforcement connected by lap joints, resource conservation can be realized. Furthermore, since internal thread machining is not required in the connecting structural members, costs can be reduced.

[0016] A steel reinforcement structure using the reinforcing bar of the present invention is constructed by wrapping the reinforcing bar of the present invention around the outer periphery of a plurality of parallel main bars, and by binding the intersection of the main bars and the reinforcing bar with a binding wire; the binding wire has: a first part wrapped around the main bar; a second part wrapped around the reinforcing bar; and a connecting part that connects the first part and the second part in a state where their axes are orthogonal to each other; the binding wire is loosely wound in such a way that the main bars and the reinforcing bar can be detached axially from the main bars.

[0017] Based on this configuration, a steel cage pre-assembled in the factory by wrapping reinforcing bars around the main reinforcing bars can be folded as a whole without changing the positional relationship between the reinforcing bars and the main reinforcing bars. This facilitates handling and enables efficient assembly and operation of the steel bars.

[0018] Any combination of at least two components disclosed in the claims and / or specification and / or drawings is also included in this invention. In particular, any combination of two or more claims in the claims is also included in this invention.

[0019] The present invention can be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and explanation only and should not be used to determine the scope of the invention. The scope of the invention is determined by the appended claims. In the accompanying drawings, the same element symbols in most of the drawings represent the same or equivalent parts.

Implementation Method

[0021] [First Embodiment] The first embodiment of the present invention will be described together with Figures 1 to 4. As shown in Figure 1, the reinforcing bar 10 is a shearing reinforcing bar in which a plurality of main bars are wrapped around the outer periphery 1. The bar body 12 is a bar with a diameter of D10 to D13 or D16 mm made of a steel bar material with elasticity (e.g., SD345, SD390, SD490, high-strength shearing reinforcing bar, etc.), and is bent into a slightly rectangular shape, and has a large first connection gap 20 in the middle in its natural state. As shown in Figure 3, when the external threads 12c of the two ends 12a and 12b of the rib body 12 are relatively long, the connecting member (connector) 14 is locked into one end 12a of the two ends 12a and 12b of the rib body 12 facing opposite directions, and the rib body 12 is elastically deformed by external force to bring the two ends 12a and 12b closer together, so that the other end 12b of the rib body 12 is locked into the connecting member 14, so that the two ends 12a and 12b face each other with a second connection gap 21 that is smaller than the first connection gap 20. Therefore, the two ends 12a and 12b of the reinforcing bar body 12 are connected by threads via the connecting member 14. In this connected state, due to the elastic restoring force (tension) F1 and F2 of the reinforcing bar body 12, the external threads 12c of the two ends 12a and 12b contact the internal threads 14c of the connecting member 14 with a fixed force in the direction in which the two ends 12a and 12b are disengaged from the connecting member 14. The reinforcing bar body 12 can also be a special-shaped reinforcing bar with ribs 40 and bamboo joints 41 formed on the outer surface of the reinforcing bar shaft, as shown in Figures 9A and 9B.

[0022] To further stabilize the connection between the connecting member 14 and the reinforcing rib 10, the connection can be achieved by applying pressure from the radially outer direction to one of the contact portions of the connecting member 14 and the rib body 12, thereby converging the joint radially. This ensures that the internal thread 14c of the connecting member 14 and the external threads 12c at both ends 12a and 12b remain in contact under tension F1 and F2, thus guaranteeing the required performance for the reinforcing rib 10. This series of operations is typically performed in a factory. Manufacturing is carried out by threading the ends of materials cut to the required length, bending them into a predetermined rectangle, installing the connector, processing, and converging the joint. These steps can be automated.

[0023] Figure 4 shows the state in which one end 12a of the rib body 12 contacts the internal thread 14c of the connecting member 14. Similarly, due to F2 (Figure 3), the other end 12b of the rib body 12 contacts the internal thread 14c of the connecting member 14 with a fixed force in the direction of disengagement from the connecting member 14. As a result, the required performance for the reinforcing rib 10 can be ensured without using a lock nut.

[0024] [Second Embodiment] As shown in FIG5, when the external thread 12c of one end 12a of the rib body 12 is shorter and the external thread 12c of the other end 12b is longer, the connecting member 14 is pre-installed on the external thread 12c of the other end 12b of the rib body 12, and the two ends 12a and 12b are connected by locking the connecting member 14 into one end 12a of the rib body 12. Then, the short thread side, i.e., one end 14a, of the connecting member 14 is forcefully locked into the incomplete thread portion 12ca of one end 12a of the rib body 12. By locking as described above, even if there is a long thread side 12b that cannot be locked by the incomplete thread portion 12ca, a lock nut is not used, and the performance required for the reinforcing rib 10 can be ensured.

[0025] Regarding beams, the reinforcement arrangement of the reinforcing bars 10 is generally carried out by supporting the upper reinforcing bar 1A. However, in the reinforcing bars of the present invention connected by the connecting member 14, as shown in FIG. 6, during concrete pouring, the connecting member 14 bears the weight of the lower reinforcing bar 1B by supporting the middle reinforcing bar 1C with a suspension line 25 within the space of the formwork 30. The two ends of the suspension line 25 are fixed to the formwork 30, for example, by pins 27. In this way, a force equivalent to the weight of the lower reinforcing bar 1B is further applied to the internal thread 14c of the connecting member 14 in the direction of disengagement from the connecting member 14, thereby improving the effect of ensuring the required tensile strength or rigidity for the reinforcing bar 10.

[0026] The external thread 12c of the rib body 12 shown in Figures 3 to 5 is a rolled thread, which becomes harder than other parts of the rib body 12, at least the surface part, through work hardening (also known as plastic hardening).

[0027] The length of the external thread 12c only needs to be the length required to lock into the connector 14, as shown in Figure 7, and is set to the length L of the entire connector 14 that can be locked into. Therefore, during the connection operation of the two ends 12a and 12b of the rib body 12, by first locking the entire connector 14 into the external thread 12c of the other end 12b, and while the end faces of the rib body 12 are joined together or close to each other, the connector 14 is loosened and moved to the left side of Figure 7, so that the connector 14 is screwed into the external thread 12c of one end 12a, thus achieving the connection state shown in Figures 3 to 5. Therefore, it is no longer necessary to simultaneously stretch the two ends 12a and 12b of the rib body 12 while locking the connector 14 in, thus improving the operability of the on-site connection. The cross-sectional shape of the thread groove of the external thread 12c can also be triangular or trapezoidal.

[0028] Based on this rebar joint, the reinforcing bar 10 is connected by locking the external threads 12c, 12c of the bar body 12 into the connector 14. In the same way as a general rebar joint, the rebar configuration can be simplified and the construction period can be shortened.

[0029] [Third Embodiment] A fourth embodiment of the invention will be described together with FIG8. As shown in FIG8, this reinforcing rib 10 is constructed the same as the first embodiment, except that the rib body 12 is connected midway by another connecting member (connector) 15. Therefore, even when the rib body 12 is wound around a longer main rib of a large column or beam, the rib body 12 can be easily elastically deformed without a large external force, so that the two ends 12a, 12b of the rib body 12 approach each other. Regarding the other connecting member (connector) 15 provided midway, it is preferable to provide an anti-loosening nut to eliminate loosening.

[0030] [Fourth Embodiment] As shown in Figure 9A, the external threads 2c of the two ends 2a, 2b of the main reinforcement 1 are inserted into the cylindrical connecting member 16, which has not undergone internal threading. The connecting member 16 and the external threads 2c are then threaded together by radial convergence. In this way, without performing internal threading on the connecting member 16, the same performance as the main reinforcement 1 connected by a lap joint can be achieved. Furthermore, since internal threading on the connecting member 16 is not required, costs can be reduced. Although the joints of the irregularly shaped reinforcement are shown as bamboo joints in Figures 9A and 9B, they can also be threaded joints. Although the main reinforcement 1 is an irregularly shaped reinforcement with ribs 40 and bamboo joints 41 formed on its outer periphery, a main reinforcement composed of a normal reinforcement shaft can also be used. This connection method can also be used for reinforcing bars.

[0031] In the main reinforcement of small-scale foundations such as residential buildings, a large number of small-diameter steel bars are used, and the connection method is lap splices. The length of this overlap is huge on a national scale, resulting in a waste of resources. Since the shape of the steel bars using the lap splice method does not need to be closed, resources can be saved by adopting this lap splice method.

[0032] When the reinforcing bar body 2 is an irregularly shaped reinforcing bar, the incomplete threaded portion 2ca is due to the pre-cutting process for thread rolling, resulting in defects in the rib. Therefore, the cross-sectional area is reduced compared to the non-defective portion, and the tensile strength is lower. Thus, if the length of the connecting member 16 is set such that the incomplete threaded portions 2ca and 2ca are entirely contained within the inner side of the connecting member 16, the tensile strength becomes equal to that of the non-defective portion. Whether the length of the connecting member 16 is set such that the incomplete threaded portions 2ca and 2ca are entirely contained within the inner side of the connecting member 16, or that the incomplete threaded portions 2ca and 2ca are exposed on the outer side of the connecting member 16, is preferably determined based on the performance required for the joint.

[0033] Although the external thread 12c of the rib body 12 in the first to fourth embodiments is helical, in the external thread 2c of the fifth embodiment, annular protrusions, also known as parallel threads 2d, can be provided at equal intervals in the axial direction, as shown in FIG9B. In parallel threads, there are no incomplete thread portions; all are complete threads. Therefore, compared to the case of using a helical thread, even if a short connecting member 16 is used, the required reinforcement performance for the main rib 1 can be ensured.

[0034] In the case of FIG9B, the rib section defect 42 is designed to be entirely contained within the connecting member 16. As described above, by overlapping the connecting member 16 with the rib section defect 42, not only the performance required for the joint, but also the performance required for the rib body 12 can be ensured.

[0035] Furthermore, in the assembly of steel bars on the construction site, it is necessary to distribute the steel bars to the locations where they are placed, and some of the steel bars are pre-bent and processed in the factory. On the other hand, pre-assembling this part and placing only this part on site requires transporting large-volume objects during the transportation process, resulting in a lot of waste. Therefore, if a method of folding a "steel cage using main bars and reinforcing bars and pre-assembled in the factory" is adopted, transportation can be carried out efficiently. This method is called the serpentine method. Although this serpentine method has been disclosed in Japanese Patent No. 3839963, it has the disadvantage of costly because it requires the installation of expansion joints at each binding line.

[0036] In the snake-belly method, the binding wire 28A on the main reinforcement side is a tightly bound loop, and the binding wire 28B on the reinforcing bar side is cut to retain a loose loop for binding. As shown in Figure 11, the beam is placed horizontally during folding, and folding is performed, for example, by pushing the upper reinforcing bar 1A towards the long side to move it (Figure 12). As shown in Figures 10A and 10B, at the connection 29, when the binding wire 28A wound on the main reinforcement 1 side and the binding wire 28B wound on the reinforcing bar 10 side are orthogonal, when folding the assembled steel cage, the entire structure can be folded 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, some shear reinforcement bars are not positioned at right angles to the main reinforcement bars. Therefore, when folded as described above, there is a problem of the rotation axis (the axis of the upper reinforcement bar 10 in Figure 11) being inconsistent across the upper reinforcement bars. Therefore, by loosely fixing the binding wires 28A and 28B, the reinforcement body 12 can move within the gap with the binding wire 28A, thus allowing for a certain degree of misalignment of this rotation axis. The binding wires 28A and 28B are orthogonal at the intersection of the main reinforcement bar 1 and the reinforcement bar 10 by rotating them 90° using tools such as wire hooks. Thus, the volume of the reinforcement structure containing the main reinforcement bar 1 and the reinforcement bar 10 is reduced, and it is transported to the site and installed. After installation, the main reinforcement bars and shear reinforcement bars are securely bundled to complete the assembly. As described above, according to the bundling method of the present invention, since it is not necessary to use components other than the binding wires, such as expansion joints, costs can be reduced. In addition, for the sake of simplicity, only the upper end steel bar 1A and the lower end steel bar 1B are shown in Figures 11 and 12.

[0037] Although the embodiments for implementing the present invention have been described above, all the key points of the embodiments disclosed herein are merely illustrative and not limiting. For example, the rib body 12 may also be bent into a rectangle, a circle, or an ellipse. The scope of the present invention is defined by the scope of the claims, not by the above description; all modifications within the scope and meaning of the same as the scope of the claims are included in the present invention.

[0038] The preferred embodiments have been described above with reference to the drawings, but various additions, modifications, and deletions may be made without departing from the spirit of the present invention. Therefore, such additions and modifications are also included within the scope of the present invention. [Simplified Explanation of the Diagram]

[0020] [Fig. 1] is a front view of a bent reinforcing bar according to the first embodiment of the present invention. [Fig. 2] is a front view of a connected reinforcing bar according to the same embodiment. [Fig. 3] is a longitudinal sectional view of a connecting member according to the same embodiment. [Fig. 4] is an enlarged view of the connection portion of the connecting member with the reinforcing bar. [Fig. 5] is a longitudinal sectional view of a connecting member according to the second embodiment of the present invention. [Fig. 6] is a longitudinal sectional view of a method for supporting the steel structure of the present invention within a formwork. [Fig. 7] is a longitudinal sectional view of an example of the step of locking the reinforcing bar body into the connecting member. [Fig. 8] is a front view of a bent reinforcing bar according to the third embodiment of the present invention. [Fig. 9A] is a longitudinal sectional view of a connecting member according to the fourth embodiment of the present invention. [Fig. 9B] is a longitudinal sectional view of a modified example of the reinforcing bar body according to the same embodiment. [Figure 10A] is a front view showing the binding wires wound around the main reinforcement and reinforcing bars of the present invention. [Figure 10B] is a perspective view showing the binding wires wound around the main reinforcement and reinforcing bars of the present invention. [Figure 11] is a perspective view showing the state of the steel reinforcement structure of the present invention before folding. [Figure 12] is a perspective view showing the state of the steel reinforcement structure of the present invention after folding.

Claims

1. A reinforcing bar, wherein a plurality of main reinforcing bars are wrapped around the outer periphery, wherein, The rib body is closed in shape and is given a first connection gap in the middle in its natural state. When the rib body is elastically deformed by external force so that the two ends of the rib body are close to each other and the two ends face each other with a second connection gap smaller than the first connection gap, the two ends of the rib body are connected by a connecting member in a threaded manner. In the connected state, due to the elastic restoring force of the rib body, the external threads of the two ends contact the internal threads of the connecting member in the direction in which the two ends are disengaged from the connecting member.

2. A method for connecting reinforcing ribs, wherein when using reinforcing ribs to wrap around a plurality of main ribs from the outer periphery, the rib body is bent into a closed shape, and a first connection gap is provided in the middle in a natural state. When the rib body is elastically deformed by external force so that its two ends are close to each other, and the two ends face each other with a second connection gap smaller than the first connection gap, the two ends of the rib body are connected by a connecting member in a threaded manner. In this connected state, due to the elastic restoring force of the rib body, the external threads of the two ends contact the internal threads of the connecting member in the direction in which the two ends disengage from the connecting member.

3. A main rib, comprising: a plurality of rib bodies, each having an external thread formed at at least one end; and a connecting member having insertion holes into which the external thread can be inserted from both ends; inserting the thread as the external thread into the insertion holes of the connecting member; and joining the connecting member and the thread by means of a radially converging joint.

4. A reinforced concrete structure, wherein the reinforcing bar described in claim 1 is wound around the periphery of a plurality of parallel main reinforcing bars, and the intersection of the main reinforcing bars and the reinforcing bar is bound by a binding wire; the binding wire has: a first portion wound around the main reinforcing bar; a second portion wound around the reinforcing bar; and a connecting portion connecting the first portion and the second portion in a state where the axes of the two portions are orthogonal to each other; the binding wire is loosely wound in such a way that the main reinforcing bars and the reinforcing bars can be detached axially from the main reinforcing bars.

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