[Technical Field]

The present invention relates to a reinforcing rod including a rounded three-square or four-square steel twisted in a longitudinal direction as a screw, and a reinforcing rod coupler including a rounded three-square or four-square tubular member having a hollow portion therein twisted in a longitudinal direction as a screw, in which the reinforcing rod and the reinforcing rod coupler can be easily manufactured, its bond strength with concrete and hardness can be significantly increased without having a variation to its orientation and without using a lot of materials, and the reinforcing rods can be easily connected to each other by using the reinforcing rod coupler on a spot, without performing additional operation. [Background Art]

Reinforcing rods are embedded into concrete in order to reinforce tensile stress relatively lower than compressive stress in concrete structures. The reinforcing rod should have good bond strength with concrete, high strength and yield point, good flexibility, easy workability, high corrosion resistance, and easy joint. These properties can be satisfied by increasing a thickness of the reinforcing rod. However, if the reinforcing rod is thickened, the material is wasted, which is an inadequate method at this point when costs of raw materials are raised. Among the above physical properties of the reinforcing rod, the i yield point, the flexibility and the corrosion resistance are influenced by the material of the reinforcing rod or the physical property of the material, while the bond strength with the concrete, the strength and the easy workability are influenced by a sectional shape of the reinforcing rod. The sectional shape of the reinforcing rod is closely concerned with a use amount of the material.

The reinforcing rod is classified into a smooth circular reinforcing rod and a deformed reinforcing rod with a recessed surface. The circular reinforcing rod has a smooth surface with no boss on a surface of steel. Since bond strength and slip resistance are relatively low, the circular reinforcing rod is almost not used recently.

The deformed reinforcing rod with recessed portions, such as ribs and joints, has advantages of high bond strength and slip resistance. FIGs. 1 to 3 are a perspective view, a side view and a cross- sectional view of a conventional deformed reinforcing rod. An existing deformed reinforcing rod 10 includes a rod 11 having ribs 12 symmetrically protruding from the surface in a longitudinal direction, and joints 13 spaced longitudinally apart from each other at regular intervals.

The deformed reinforcing rod 10 has a section, as shown in FIG. 3. Since the sectional shape has high moment of inertia in y-axis and low moment of inertial in x-axis, there is a variation at bending stiffness of the reinforcing rod depending upon whether the reinforcing rod is oriented. Since the joints 13 are spaced apart from each other at regular intervals in a longitudinal direction, the joint 13 is involved in the increase of the bond strength with the concrete, but is not of help to increase the bending stiffness of the reinforcing rod. Therefore, the conventional deformed reinforcing rod 10 does not effectively utilize the material.

In order to connect the reinforcing rods in a longitudinal direction, overlap fastening, mechanical fastening (e.g. screw joining, filing joining, and compressive joining) and welding are used. The overlap fastening has a drawback of wasting the reinforcing rod by an overlapped length. The screw joining also has a drawback of machining an end of the reinforcing rod as a screw when the reinforcing rod is connected to other reinforcing rod. The filing joining, the compressive joining and the welding are labor intensive since the joining is performed on a spot. [Disclosure] [Technical Problem]

Therefore, the present invention has been made in view of the above-mentioned problems. An object of the present invention is to provide a reinforcing rod and a reinforcing rod coupler, in which the reinforcing rod and the reinforcing rod coupler can be easily manufactured, its bond strength with concrete and hardness can be significantly increased without having a variation to its orientation and without using a lot of materials, and the reinforcing rods can be easily connected to each other by using the reinforcing rod coupler on a spot, without performing additional operation. [Technical Solution]

In order to achieve the above and other objects, there is provided a reinforcing rod including a rounded three-square or foursquare steel twisted in a longitudinal direction as a screw having a certain lead. Since the three-square or four-square section has moment of inertia larger than that of a circular section, the reinforcing rod has large stiffness, as compared with the circular reinforcing rod made of the same amount of material as the three-square or foursquare steel. Since the three-square or four-square steel is formed in helix, it has high bond strength with the concrete, and compensates a variation of bending stiffness to its orientation. In particular, if the steel is formed to have a constant lead, it is very convenient in that the reinforcing rod is connected to other reinforcing rod by using a reinforcing rod coupler which will be described hereinafter, without performing additional operation.

Preferably, a rib protrudes from a center portion of the respective sides of the three-square or four-square steel. The bond strength with the concrete is increased by the rib. Since the rib is positioned at the center portion of the respective sides, it compensates the bending stiffness for a bending direction which will be weak in terms of the moment of inertia. Preferably, the lead is set as about 1.5 to 3.5 times of a diameter of the reinforcing rod, and a slope of a thread with respect to a longitudinal direction of the reinforcing rod is about 40 to 65 degrees. More preferably, the lead is set as about 3 times of the diameter of the reinforcing rod, and the slope of the thread with respect to a longitudinal direction of the reinforcing rod is about 45 degrees. It is possible to eliminate the inconvenience in that any one of reinforcing rods should be rotated several dozen times when two reinforcing rods are connected to each other by a conventional female-thread-type fastening method. If the lead is about 1.5 to 3.5 times of a diameter of the reinforcing rod, the reinforcing rod can be engaged to the reinforcing rod coupler by a length corresponding to 1.5 to 3.5 times of the diameter of the reinforcing rod by rotating the reinforcing rod only once. Therefore, the reinforcing rod can be engaged with the reinforcing rod coupler along a distance corresponding to 10 times of a diameter of the reinforcing rod by rotating the reinforcing rod 3 to 7 times. Since the concrete is well bonded with the three-square or four-quarter reinforcing rod, there is nothing to worry about the separation of the reinforcing rod 20 from the concrete due to rotation of the reinforcing rod in the concrete.

Also, there is provided a reinforcing rod coupler including a rounded three-square or four-square tubular member having a hollow portion therein twisted in a longitudinal direction as a screw having a certain lead. The coupler of the present invention has a three-square or four-quarter shape formed in a helix to increase the bond strength with the concrete. Also, since the hollow tubular section increases the moment of inertia, it solves the rigidity of the reinforcing rod structure without using a lot of materials.

Preferably, a rib accommodating portion protrudes from a center portion of the respective sides of a triangle or square in a longitudinal direction in order to accommodate the ribs of the reinforcing rod. Preferably, the lead is set as about 1.5 to 3.5 times of a diameter of the reinforcing rod.

There is no doubt that the lead is identical to that of the reinforcing rod.

The reinforcing rod coupler is provided at a center portion thereof with an opening, through which an inserted depth of the reinforcing rod is verified. The insertion depth of the reinforcing rod can be verified by using the openings, and the concrete is poured through the openings to strongly bond the concrete and the reinforcing rod. Also, an inlet is formed on the other side of the center portion of the reinforcing rod coupler, so that epoxy can be introduced into the inside of the coupler through the inlet to firmly fix the reinforcing rods which are connected to each other by the reinforcing rod coupler.

Also, a plurality of reinforcing rod couplers having the same lead and different diameter can be overlapped over each other to connect the reinforcing rods having a different diameter.

In addition, there is provided a structure for connecting reinforcing rods including two reinforcing rod each including a rounded three-square or four-square steel twisted in a longitudinal direction as a screw having a certain lead, and a reinforcing rod coupler including a rounded three-square or four-square tubular member having a hollow portion therein twisted in a longitudinal direction as a screw having the same lead as that of the reinforcing rod, in which the two reinforcing rods are connected to each other by rotating and inserting each ends of the reinforcing rods into both ends of the reinforcing rod coupler. The structure can maintain the stiffness of the reinforcing rod and the reinforcing rod coupler strongly, and connect two reinforcing rods on a spot or at a manufacturing stage, without performing an additional assembling process.

A plurality of reinforcing rod couplers having the same lead and different diameter are overlapped over each other when the ends of the reinforcing rods are connected to each other.

By using such overlapping methods, if, for example, one reinforcing rod having a small diameter is connected to one side of one reinforcing rod coupler having a small diameter while the other reinforcing rod having a large diameter is connected to one side of the other reinforcing rod coupler having a large diameter, it is very easy to connect two reinforcing rods that have different diameters. [Advantageous Effects]

With the above description, the reinforcing rod and the reinforcing rod coupler can be easily manufactured, its bond strength with concrete and hardness can be significantly increased without having a variation to its orientation and without using a lot of materials, and the reinforcing rods can be easily connected to each other by using the reinforcing rod coupler on a spot, without performing additional operation. [Description of Drawings]

The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a conventional deformed reinforcing rod;

FIG. 2 is a side view of a conventional deformed reinforcing rod; FIG. 3 is a cross-sectional view of a conventional deformed reinforcing rod;

FIG. 4 is a perspective view of a deformed reinforcing rod according to a first embodiment of the present invention;

FIG. 5 is a side view of a deformed reinforcing rod according to a first embodiment of the present invention; FIG. 6 is a cross-sectional view of a deformed reinforcing rod according to a first embodiment of the present invention;

FIG. 7 is a perspective view of a reinforcing rod coupler according to a first embodiment of the present invention;

FIG. 8 is a side view of a reinforcing rod coupler according to a first embodiment of the present invention;

FIG. 9 is a cross-sectional view of a reinforcing rod coupler according to a first embodiment of the present invention;

FIG. 10 is a perspective view illustrating an example of a coupling using the deformed reinforcing rod in FIG. 4 and the reinforcing rod coupler in FIG. 7; FIG. 11 is a cross-sectional view of the coupled portion in FIG. 10;

FIG. 12 is a perspective view of a deformed reinforcing rod according to a second embodiment of the present invention; FIG. 13 is a side view of a deformed reinforcing rod according to a second embodiment of the present invention;

FIG. 14 is a cross-sectional view of a deformed reinforcing rod according to a second embodiment of the present invention;

FIG. 15 is a perspective view of a reinforcing rod coupler according to a second embodiment of the present invention;

FIG. 16 is a side view of a reinforcing rod coupler according to a second embodiment of the present invention;

FIG. 17 is a cross-sectional view of a reinforcing rod coupler according to a second embodiment of the present invention; FIG. 18 is a perspective view illustrating an example of a coupling using the deformed reinforcing rod in FIG. 12 and the reinforcing rod coupler in FIG. 15;

FIG. 19 is a cross-sectional view of the coupled portion in FIG. 18; FIG. 20 is a perspective view of a reinforcing rod coupler with an opening formed at a side thereof; and

FIG. 21 is a view illustrating the state in which a plurality of reinforcing rods are connected to each other and reinforcing rods having different diameters are engaged to both sides of the reinforcing rods; FIG. 22 is a view illustrating the state in which two reinforcing rods are connected to each other by overlapping a plurality of reinforcing rod couplers; and

FIG. 23 is a view illustrating a modified embodiment of the reinforcing rods and the reinforcing rod coupler shown in the first and second embodiments. [Best Mode]

A reinforcing rod and a reinforcing rod coupler according to a first embodiment of the present invention will now be described in detail with reference to accompanied drawings.

FIGs. 4 to 6 are a perspective view, a side view and a cross- sectional view each illustrating a deformed reinforcing rod according to the first embodiment of the present invention.

A reinforcing rod 20 of the present invention is made by twisting a rounded three-square steel 21, with a rib 22 protruding from a center portion of the respective sides of a triangle. In this instance, a lead of a helix is constant in a longitudinal direction of the steel, and is three times of a diameter (thickness) of the steel 20. A lead angle of the helix is 45 degrees which is larger than that of a conventional screw, as shown in FIG. 4, so that the helix is extended in a longitudinal direction of the reinforcing rod.

The rounded three-square steel can be easily manufactured by extruding or rolling.

The three-square steel has excellent bending stiffness since moment of inertia thereof is larger than that of a circular steel having the same area. Consequently, the present invention can reduce an amount of materials.

By forming the steel as a screw, a helix is formed on the circumferential surface of the reinforcing rod 20 to increase bond strength with concrete. Since its section is twisted as the helix, a variation of the bending stiffness to its orientation can be compensated.

In particular, if the reinforcing rod 20 is manufactured to have a constant lead angle, the reinforcing rod 20 can be easily connected to other reinforcing rod 20 by using only a coupler 30 which will be described herein.

Since the bond strength with the concrete is increased by the rib

22 which is positioned at a center portion of the respective sides, it reinforces the bending stiffness in a bending direction which can be relatively weak in a triangular section in terms of the moment of inertia.

If a screw thread is 45 degrees or more, it is possible to remove the inconvenience that any one of reinforcing rods 20 should be rotated a few dozen times when two reinforcing rods are connected to each other. Since the reinforcing rod 20 has a corrugated surface which is formed by twisting the three-quarter steel in a longitudinal direction thereof, concrete is well bonded to the reinforcing rod. Consequently, there is nothing to worry about the separation of the reinforcing rod 20 from the concrete.

FIGs. 7 to 9 are a perspective view, a side view and a cross- sectional view each illustrating the reinforcing rod coupler according to the first embodiment of the present invention.

A reinforcing rod coupler 30 according to the present invention is made by twisting a rounded three-square tubular member 31 having a hollow portion therein, with a rib accommodating portion 32 protruding from a center portion of the respective sides of a triangle. In this instance, a lead of a helix is constant in a longitudinal direction of the reinforcing rod coupler 30, and is 3 times of a diameter of the reinforcing rod coupler 30 which is identical to that of the reinforcing rod 20. A lead angle of the helix is 45 degrees which is larger than that of a conventional screw, as shown in FIG. 4, so that the helix is extended in a longitudinal direction of the reinforcing rod.

Although the tubular member 31 has a sectional area different from that of the reinforcing rod 20, the tubular member 31 has excellent bending stiffness since moment of inertia thereof is too larger. Also, since the tubular member 31 has a three-quarter surface which is twisted in a helix shape, the reinforcing rod coupler 30 has increased bond strength with concrete. The section is twisted as the helix in a longitudinal direction, so that a variation of the bending stiffness to its orientation can be compensated. In particular, if the reinforcing rod coupler 30 is manufactured to have the same lead angle as that of the reinforcing rod 20, the reinforcing rod 20 can be easily connected to other reinforcing rod 20 by using only the coupler 30.

The rib accommodating portion 32 accommodates the rib 22 of the reinforcing rod 20, and the rib accommodating portion 32 itself protrudes from the circumferential surface of the tubular member 31 to increase the bond strength with the concrete. Also, since the rib accommodating portion 32 is positioned at the center portion of the respective sides, it reinforces the bending stiffness in a bending direction which can be relatively weak in a triangular section in terms of the moment of inertia.

By forming a screw thread in 45 degrees or more, it is possible to remove the inconvenience that any one of reinforcing rods 20 should be rotated a few dozen times when two reinforcing rods are connected to each other. Since the reinforcing rod 20 has a corrugated surface which is formed by twisting the three-quarter steel in a longitudinal direction thereof, the concrete is well bonded to the reinforcing rod. Consequently, there is nothing to worry about the separation of the reinforcing rod 20 or the reinforcing rod coupler 30 from the concrete.

FIG. 10 is a perspective view illustrating an example of the coupling using the deformed reinforcing rod in FIG. 4 and the reinforcing rod coupler in FIG. 7, and FIG. 11 is a cross-sectional view of the coupled portion in FIG. 10. It will be seen that the steel 21 and the ribs 22 of the reinforcing rod 20 are longitudinally accommodated in the tubular member 31 and the rib accommodating portion 32 of the reinforcing rod coupler 30 by rotating the steel 21 several times. Additional coupling operation is not required to connect the reinforcing rod 20 with the reinforcing rod coupler 30. Also, it can connect the reinforcing rod with the reinforcing rod coupler on a spot since the number of rotations of the heavy reinforcing rod having a length of 8m or more.

As shown in the cross-sectional view, there is a small gap between the reinforcing rod 20 and the reinforcing rod coupler 30, the connected portion is freely moved in the gap to provide an earthquake-proof effect.

The deformed reinforcing rod and a reinforcing rod coupler according to a second embodiment of the present invention will now be described, in which the same features as those shown and described in the first embodiment will be omitted.

FIGs. 12 to 14 are a perspective view, a side view and a cross- sectional view each illustrating a deformed reinforcing rod according to the second embodiment of the present invention.

A reinforcing rod 40 of the present invention is made by twisting a rounded four-square steel 41, with a rib 42 protruding from a center portion of the respective sides of a square.

The rounded four-square steel can be easily manufactured by extruding or rolling.

The rounded four-square steel has excellent bending stiffness since moment of inertia thereof is larger than that of a circular steel having the same area. A perfect square has advantage over a regular triangle in terms of small variation of the moment of inertial to its orientation. In addition, the four-square steel has the same features as those of the three-square steel 20. FIGs. 15 to 17 are a perspective view, a side view and a cross- sectional view each illustrating the reinforcing rod coupler according to the second embodiment of the present invention.

A reinforcing rod coupler 50 according to the second embodiment of the present invention is made by twisting a rounded four-square tubular member 51 having a hollow portion therein, with a rib accommodating portion 52 protruding from a center portion of the respective sides of a square. The four-square tubular member 51 has advantage over the regular triangle in terms of small variation of the moment of inertial. In addition, the rounded four-square reinforcing rod coupler 50 has the same features as those of the three-square reinforcing rod coupler 30.

FIG. 18 is a perspective view illustrating an example of a coupling using the deformed reinforcing rod in FIG. 12 and the reinforcing rod coupler in FIG. 15, and FIG. 19 is a cross-sectional view of the coupled portion in FIG. 18.

It will be seen that, since a lead angle is large, the steel 41 and the ribs 42 of the reinforcing rod 40 are longitudinally accommodated in the tubular member 51 and the rib accommodating portion 52 of the reinforcing rod coupler 50 by rotating the steel 41 several times. FIG. 20 is a side view illustrating the state in which an opening

33 is formed at one side of the reinforcing rod coupler shown in the above embodiment, and an inlet 34 is formed at the other side. Two openings 33 are formed at the center portion of the coupler in a longitudinal direction. When the reinforcing rod is inserted to the left side of the coupler in FIG. 20, the full insertion of the reinforcing rod is verified through a left opening 33a. When the reinforcing rod is inserted to the right side of the coupler, the full insertion of the reinforcing rod is verified through a right opening 33b.

In the case where the reinforcing rod is inserted at the left side, the reinforcing rod is not fully inserted if the reinforcing rod is not seen through the left opening 33a. The reinforcing rod is excessively inserted if the reinforcing rod is seen through the left and right openings 33a and 33b. Consequently, ends of the both reinforcing rods can abut against each other at the center portion of the reinforcing rod coupler by using both openings.

The insertion depth of the reinforcing rod can be verified by using the openings, and the concrete is poured through the openings to strongly bond the concrete and the reinforcing rod.

Epoxy can be introduced into the inside of the coupler 30 through the inlet 34 formed at the center portion of the other side to firmly fix the reinforcing rods 20 which are connected to each other by the reinforcing rod coupler 30.

FIG. 21 is a view illustrating the state in which the plurality of reinforcing rods are connected to each other and the reinforcing rods having different diameters are engaged to both sides thereof.

According to the present invention, several reinforcing rod couplers 30 and 30a having different diameter may be provided so that one steel coupler 30a is placed over the reinforcing rod coupler 30.

It can connect the reinforcing rods 20 and 20a having different diameter. For example, if it is needed that the reinforcing rods 20 and 20a having different diameter (i.e. a diameter of the reinforcing rod 20 is smaller than that of the reinforcing rod 20a) are engaged to each other, the reinforcing rod coupler 30 having a diameter corresponding to the reinforcing rod 20 can be connected to the reinforcing rod coupler 30a having a diameter corresponding to the reinforcing rod 20a(i.e. a diameter of the reinforcing rod coupler 30 is smaller than that of the reinforcing rod coupler 30a). As shown in FIG. 21, the reinforcing rod coupler 30 having the small diameter is connected to the left reinforcing rod 20 having the small diameter, the reinforcing rod coupler 30a having the large diameter is connected to the left reinforcing rod coupler 30, and then the reinforcing rod 20a having the large diameter is connected to the left reinforcing rod coupler 30a, thereby easily connecting the reinforcing rod 20 having the small diameter with the reinforcing rod 20a having the large diameter.

As shown in FIG. 22, in the case where the thick reinforcing rod 20 is used to support the heavy load, it can reinforce the reinforcing rod coupler by overlapping the reinforcing rod couplers 30 and 30a. As described above, the reinforcing rod and the reinforcing rod coupler can be easily manufactured, and the bond strength with the concrete and the hardness which are constant to its orientation can be significantly increased, without using a lot of materials. It can easily connect the reinforcing rod with the reinforcing rod coupler on a spot, without performing additional operation, which can reduce working times and costs. Meanwhile, the reinforcing rod and the reinforcing rod coupler shown in FIG. 23 may have a rounded three-quarter or four-quarter shape.

While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiment and the drawings. On the contrary, it is intended to cover various modifications and variations within the spirit and scope of the appended claims. [Industrial Applicability]

The present invention can be utilized in the field of civil engineering and construction employing reinforcing rods and couplers.