SHEAR REINFORCEMENT FOR REINFORCED CONCRETE STRUCTURE

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase of PCT Patent Application No. PCT/KR2012/009286 having International filing date of Nov. 6, 2012, which claims the benefit of priority of Korean Patent Application No. 10-2011-0115813 filed on Nov. 8, 2011. The contents of the above applications are all incorporated by Reference as if full set forth herein in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to a shear reinforcement for a reinforced concrete structure, and more particularly, to a shear reinforcement for a reinforced concrete structure that is installed in a reinforced concrete structure to increase resistance against shear failure and can be installed after the arrangement is finished at the time of constructing.

Since a reinforced concrete structure that is constructed by applying a reinforcing bar and concrete, especially a slab, a girder or a beam, a column, a wall, or a corbel, needs to increase shear resistance, a shear reinforcement for reinforcing shear performance is applied at the time of constructing.

The present inventor proposed a shear reinforcement for a reinforced concrete structure for overcoming problems in a method of applying a shear band, a method of applying a shear stud, and a method of applying a stirrup through “Shear Reinforcement with Dual Anchorage Function Each Up and Down (Korean Patent Registration No. 10-09791736).”

Since the shear reinforcement proposed by the present inventor has a structure in which anchor heads are installed at upper and lower sides of a truss including an upper chord and a lower chord that are connected by a connecting member such as a vertical member or an inclined member, a dual anchorage function is performed at the top by the upper anchor head and the upper chord and a dual anchorage function is performed at the bottom by the lower anchor head and the lower chord, so that an effect of improving shear resistance and ductility performance may be expected as compared to the aforementioned technologies.

SUMMARY OF THE INVENTION

Accordingly, the present invention is proposed to further improve usability of the shear reinforcement while maintaining the advantage of the shear reinforcement for a reinforced concrete structure proposed in the previous application by the present inventor.

In order to satisfy the aforementioned necessity, an object of the present invention is to provide a new shear reinforcement for a reinforced concrete structure that is installed in a reinforced concrete structure to increase resistance against shear failure and can be installed after the arrangement is finished at the time of constructing.

In particular, an object of the present invention is to also provide a new shear reinforcement for a reinforced concrete structure can be installed after the arrangement is finished at the time of constructing while maintaining the advantage of the shear reinforcement for a reinforced concrete structure proposed in “Shear Reinforcement with Dual Anchorage Function Each Up and Down (Korean Patent Registration No. 10-0971736)” by the present inventor.

In order to achieve the above object, an exemplary embodiment of the present invention provides a shear reinforcement for a reinforced concrete structure that is installed within a reinforced concrete structure including a slab, a girder or a beam, a column, a wall, a corbel, or a base that is constructed by applying a reinforcing bar and concrete and increases shear resistance of concrete to increase resistance against shear failure of the concrete. The shear reinforcement includes reinforcement brackets (20) that respectively include upper anchor heads (22) and lower anchor heads (24), and include connecting plates (26) that vertically fixes the upper anchor heads (22) and the lower anchor heads (24); and a connecting bar (40) that is fixed onto the upper anchor heads (22) of the reinforcement brackets (20). The number of the reinforcement brackets (20) is determined by a length in a longitudinal direction of the connecting bar (40), and the connecting bar (40) is horizontally disposed in the longitudinal direction to be fixed onto the anchor heads (22) of the plurality of reinforcement brackets (20).

In the shear reinforcement for a reinforced concrete structure, horizontal cross-sectional areas (A1) of the upper anchor head (22) and the lower anchor head (24) may be 10 times greater than a horizontal cross-sectional area (A2) of the connecting plate (26).

In the shear reinforcement for a reinforced concrete structure, the upper anchor head (22), the lower anchor head (24) and the connecting plate (26) may be formed using rectangular plates (22′, 24′ and 26′) made of a flat metal material, and may be fused to each other through welding to form the reinforcement bracket (20).

In the shear reinforcement for a reinforced concrete structure, ratio between a width and a thickness of the connecting plate (26) may be 5 times or more.

In accordance with the shear reinforcement for a reinforced concrete structure according to the present invention, it is possible to the work convenience while maximizing the shear reinforcing performance of the shear reinforcement proposed in the previous application by the present inventor.

In accordance with the shear reinforcement for a reinforced concrete structure according to the present invention, since the shear reinforcement of the present invention is inserted into the arranged reinforcing bars, the shear reinforcement 10 is installed after the arrangement is finished at the time of constructing unlike the shear reinforcement proposed in the previous application filed by the present inventor, so that it is possible to improve the convenience of the arrangement.

Further, in the shear reinforcement for a reinforced concrete structure according to the present invention, since the upper anchor head 22, the lower anchor head 24 and the connecting plate 26 are formed using the rectangular plates 22′, 24′ and 26′ made of the flat metal material and are fused to each other through welding to form the reinforcement bracket 20. it is possible to economically produce shear reinforcements of various standards required in a variety of construction sites with ease.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for describing a shear reinforcement for a reinforced concrete structure according to the technical spirit of the present invention.

FIG. 2 is a perspective view of a shear reinforcement for a reinforced concrete structure according to a preferred embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along line A-A′ of FIG. 2.

FIG. 4 is a diagram for describing preferred manufacturing examples of a reinforcement bracket in the shear reinforcement for a reinforced concrete structure according to the present invention.

FIG. 5 is a diagram for specifically describing an exclusive spacer for securing a concrete covering thickness in the shear reinforcement for a reinforced concrete structure according to the present invention.

FIG. 6 is a diagram for describing features of upper and lower anchor heads according to the preferred embodiment of the present invention.

FIG. 7 is a diagram for describing a method of constructing the shear reinforcement for a reinforced concrete structure according to the preferred embodiment of the present invention.

FIG. 8 is a diagram for describing a shear reinforcement for a reinforced concrete structure according to another preferred embodiment of the present invention.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 2 to 8. In FIGS. 1 to 8, components having the same function are assigned the same reference numeral. Meanwhile, detailed descriptions of technologies that are easily applied in general by those skilled in the art from related technologies in the art such as effects and technical configurations related to a shear reinforcement for a reinforced concrete structure, and technologies of constructing a slab and a column using the shear reinforcement in the respective drawings will not be presented. Further, in the drawings, a ratio of sizes of elements is differently illustrated or sizes of components that are coupled to each other are differently illustrated. However, in the drawings, since differences in sizes can be easily understood by those skilled in the art, separate descriptions will not be presented.

FIG. 2 is a perspective view of a shear reinforcement for a reinforced concrete structure according to a preferred embodiment of the present invention, FIG. 3 is a cross-sectional view taken along line A-A′ of FIG. 2, FIG. 4 is a diagram for describing preferred manufacturing examples of a reinforcement bracket in the shear reinforcement for a reinforced concrete structure according to the present invention, FIG. 5 is a diagram for specifically describing an exclusive spacer for securing a concrete covering thickness in the shear reinforcement for a reinforced concrete structure according to the present invention, and FIG. 6 is a diagram for describing features of upper and lower anchor heads according to the preferred embodiment of the present invention. Further, FIG. 8 is a diagram for describing a shear reinforcement for a reinforced concrete structure according to another preferred embodiment of the present invention.

Referring to FIG. 2, a shear reinforcement 10 for a reinforced concrete structure according to the preferred embodiment of the present invention includes reinforcement brackets 20, a connecting bar 40, and spacers 50. The shear reinforcement is provided within a reinforced concrete structure such as a slab, a girder or beam, a column, a wall, a corbel, or a base that is constructed by applying a reinforcing bar and concrete, and increases shear resistance of the concrete to increase resistance against shear failure of the concrete.

At this time, the reinforcement bracket 20 includes an upper anchor head 22 and a lower anchor head 24, and further includes a connecting plate 26 that is fused to the upper anchor head 22 and the lower anchor head 24 through welding to vertically fix them. The number of the reinforcement brackets 20 is determined by a length in a longitudinal direction of the connecting bar 40.

Referring to FIG. 4, in the shear reinforcement 10 for a reinforced concrete structure according to the present embodiment, the reinforcement bracket 20 is formed by welding rectangular plates 22′, 24′ and 26′ made of a flat metal material. That is, in the present embodiment, the upper anchor head 22, the lower anchor head 24 and the connecting plate 26 of the reinforcement bracket 20 are formed using rectangular plates 22′, 24′ and 26′ made of the flat metal material as shown in (a) of FIG. 4, and are fused to each other through welding to form the reinforcement bracket 20 as shown in (b) of FIG. 4. As shown in FIG. 8, holes 60 and protrusions 61 for improving coupling force to other additional components or adhering force to the concrete may be formed in the upper anchor head 22, the lower anchor head 24 and the connecting plate 26.

In general, since plates that are widely sold in various standards are applied to the structure of the reinforcement bracket 20 according to the present embodiment, it is easy to manufacture shear reinforcements of various standards required in a variety of construction sites. Furthermore, since a special processing or molding (rolling) other than welding is not used, manufacturing cost of the shear reinforcement is reduced.

Referring back to FIG. 2, in the shear reinforcement 10 for a reinforced concrete according to the preferred embodiment of the present invention, the connecting bar 40 is fixed onto the upper anchor head 22 of the reinforcement bracket 20. The connecting bar 40 is horizontally disposed in the longitudinal direction to be fixed on the upper anchor heads 22 of the plurality of reinforcement brackets 20.

As shown in FIG. 8, in the shear reinforcement 10 for a reinforced concrete according to the preferred embodiment of the present invention, various numbers of connecting bar 40 may be used, and the connecting bar may be connected in various fastening manners without departing from the technical spirit of the present invention. For example, FIG. 8 illustrates the connecting bar 40 configured in such a manner that two plates 40′ and 40″ are arranged in parallel to each other on the upper anchor heads 22 of the reinforcement brackets 20 and are fixed by bolts 42. The connecting bar 40 may be applied in various manners without departing from the technical spirit of the present invention in which the connecting bar is horizontally disposed in the longitudinal direction to be fixed on the upper anchor heads 22 of the plurality of reinforcement brackets 20.

Moreover, similarly to the reinforcement bracket 20, the connecting bar 40 may be formed using a flat rectangular plate and may be fixed to the reinforcement bracket 20 through welding. Thus, it is easy to manufacture and it is possible to reduce manufacturing cost.

In addition, as shown in FIG. 3, in the shear reinforcement 10 for a reinforced concrete structure according to the present embodiment, horizontal cross-sectional areas A1 of the upper anchor head 22 and the lower anchor head 24 are 10 times greater than a horizontal cross-sectional area A2 of the connecting plate 26, and a ratio between a width and a thickness of the connecting plate 26 is 5 times or more. The shear reinforcement maintains the advantage of the structure proposed in “Shear Reinforcement with Dual Anchorage Function Each Up and Down (Korean Patent Registration No. 10-0971736)” filed by the present inventor.

More specifically, the shear reinforcement 10 for a reinforced concrete structure according to the preferred embodiment of the present invention is obtained by further improving and developing a rectangular plate structure (see (a) of FIG. 10) in various types of anchor heads proposed in “Shear Reinforcement with Dual Anchorage Function Each Up and Down (Korean Patent Registration No. 10-0971736)” filed by the present inventor. According to the ‘reinforcement bracket structure having the connecting plate fused to the upper anchor head and the lower anchor head through welding to vertically fix them,’ in the present embodiment, the upper and lower anchor heads 22 and 24 and the connecting plate 26 have the same width B in one direction (the longitudinal direction of the connecting bar 40) (see (b) of FIG. 5). At this time, the ratio between the width and the thickness of the connecting plate 26 is 5 times or more, and the horizontal cross-sectional areas A1 of the upper and lower anchor heads 22 and 24 are 10 times or more the horizontal cross-sectional area A2 of the connecting plate 26. Thus, a sufficient anchorage effect is obtained.

In the present invention, as limitations of the cross-sectional areas of the upper and lower anchor heads 22 and 24, the ‘horizontal cross-sectional area A1 being 10 times or more the horizontal cross sectional area A2’ is applied based on a proportional relation between the most suitable cross-sectional areas for the stud and the stem which has been proposed by Abdel-Salam Mokhtar, Amin Ghali and Walter Diger et al., in “Stud Shear Reinforcement for Flat Concrete Plates,” ACI Journal (TECHNICAL PAPER), Title no. 82-60. Further, based on a research result for a long time, it can be seen through experiments that as the bearing stress applied to the inner surface of the anchor head, particularly, the circumference of the stem coming in contact with the anchor head is low, an effect of the shear reinforcement is excellent.

That is, in the present invention, as a limitation of the ratio between the width and the thickness of the connecting plate, the ‘ratio between the width and the thickness of the connecting plate being 5 times or more’ is applied based on an experiment result in which as a circumference length of the lower part of the anchor head. particularly, the stem coming in contact with the anchor head becomes longer than a circumference length πD of bar steel (a diameter D), a shear reinforcing effect is excellent. That is, when a stud bar steel and the connecting plate have the same cross-sectional area (πD²/4=t*B), in order that a circumference length 2B of the connecting plate is longer than the circumferential length πD of the stud-type circular bar steel a width B of the connecting plate preferably needs to be 5 times or more than a thickness t, and, thus, it is possible to increase the shear reinforcing effect due to an increase in the circumferential length.

Referring to FIG. 6, the shear reinforcement 10 for a reinforced concrete structure according to the present embodiment provides a further improved shear reinforcing effect than the stud type. That is, the stud type is the circular bar steel, and when a diameter is D, a circumference length of the bar steel coming in contact with the anchor head is πD. Furthermore, the circumference length is automatically determined by the diameter D but is not more increased. In contrast, the shear reinforcement 10 according to the present invention is a thin plate, and when a width of the connecting plate (the stem) 26 is B, a circumference length of the connecting plate coming in contact with the anchor head is 2B. Accordingly, even though the stud type and the shear reinforcement 10 according to the present invention have the same cross-sectional area A, the thickness t of the shear reinforcement 10 according to the present invention is decreased and the width B thereof is increased to increase the circumference length, so that it is possible to further increase the shear reinforcing effect. Moreover, an angle between the lower part of the head and the stem in the stud type is considerably larger than 90 degrees, whereas the angle is 90 degrees in the shear reinforcement according to the present invention. For this reason, even though the same force is applied, since bearing stress is less applied to the shear reinforcement than that in the stud type, it is possible to improve the shear reinforcing effect. That is, when a force P is applied to the inner surface of the anchor head in the stud type, a bearing force R applied to the concrete is increased as R=P/cosθ. However, according to the shear reinforcement proposed by the present inventor, when a force P is applied to the inner surface of the anchor head, the same bearing force R is applied to the concrete as R=P, the bearing force is less applied to the shear reinforcement than that in the stud type. Accordingly, it is possible to the shear reinforcing effect in the present invention.

Referring back to FIGS. 7 and 8, unlike an original application, in the shear reinforcement 10 for a reinforced concrete structure according to the preferred embodiment of the present invention, after a lower reinforcing bar and an upper reinforcing bar are arranged, since a connector is coupled to the upper anchor head so as to easily install the shear reinforcement 10 and the spacers 50 formed to be easily coupled to the lower anchor heads 24 of the reinforcement brackets 20 are used, even though a worker installs the shear reinforcement 10 without paying attention, the concrete covering thickness is automatically maintained. Thus, it is possible to effectively improve construction quality and to reduce construction delay.

Referring to FIG. 5, in the shear reinforcement 10 for a reinforced concrete structure according to the present embodiment, the spacer 50 includes a supporting plate 52, engagement hooks 54, and height protrusions 56. At this time, the engagement hooks 54 are arranged on both sides of the supporting plate 52 to be coupled to the lower anchor head 24 while forming a space 51 to which the lower anchor head 24 of the reinforcement bracket 20 is inserted at the both sides. Furthermore, the height protrusions 56 are formed to extend downward from the supporting plate 52 to secure a concrete covering thickness required for the shear reinforcement 10, as shown in reference numeral 24 of FIG. 7.

FIG. 7 is a diagram for describing a method for constructing the shear reinforcement for a reinforced concrete structure according to the preferred embodiment of the present invention.

A method of using the shear reinforcement 10 according to the preferred embodiment of the present invention in the concrete structure (the slab) is first described with reference to FIG. 7. As shown in (a) of FIG. 7, a lower main reinforcing bar 2 and a sub reinforcing bar 3 are installed, and at this time, in order to secure the concrete covering thickness of the lower reinforcing bar, a spacer 1 is typically placed at a lower part of the reinforcing bar. Moreover, as shown in (b) of FIG. 7, similarly to typical arrangement, an upper main reinforcing bar 4 and a sub reinforcing bar 5 are installed. In addition, as shown in (c) of FIG. 7, after the upper and lower reinforcing bars are arranged, the shear reinforcement 10 for a reinforced concrete structure according to the preferred embodiment of the present invention is inserted between the arranged reinforcing bars downward from the top. At this time, since the shear reinforcement 10 according to the present embodiment naturally secures a required covering thickness by the exclusive spacers 50, it is not necessary for the worker to perform another work for securing the concrete covering thickness of the shear reinforcement.

As stated above, although the shear reinforcement for a reinforced concrete structure according to the preferred embodiment of the present invention has been illustrated in conjunction with the aforementioned descriptions and drawings, these descriptions and drawings are merely presented as examples. It is to be appreciated that those skilled in the art can variously change or modify the embodiments without departing from the technical spirit of the present invention.

FIG. 1 is a diagram for describing the shear reinforcement for a reinforced concrete structure according to the technical spirit of the present invention.

Referring to FIG. 1, the shear reinforcement 10 for a reinforced concrete structure according to the present invention includes the reinforcement brackets 20 and the connecting bar 40, and the number of the reinforcement bracket 20 is determined by the length in the longitudinal direction of the connecting bar 40. The connecting bar 40 is horizontally disposed in the longitudinal direction to be fixed onto the upper anchor heads 22 of the plurality of reinforcement brackets 20. The shear reinforcement is provided within the reinforced concrete structure such as a slab, a girder or beam, a column, a wall, a corbel, or a base that is constructed by applying the reinforcing bar and concrete, and increases shear resistance of the concrete to increase resistance against shear failure of the concrete.

At this time, the reinforcement bracket 20 includes the upper anchor head 22 and the lower anchor head 24, and further includes the connecting plate (the stem) 26 fused to the upper anchor head 22 and the lower anchor head 24 through welding to vertically fix them. Further, the connecting bar 40 is fixed onto the upper anchor heads 22 of the reinforcement brackets 20. Naturally, the connecting plate 26 may fix the upper and lower anchor heads 22 and 24 at an arbitrary angle, when necessary.

Since the shear reinforcement 10 for a reinforced concrete structure according to the present invention is opened downward, the shear reinforcement can be constructed after the upper and lower reinforcing bars are arranged. That is, when using the shear reinforcement (“Shear Reinforcement with Dual Anchorage Function Each Up and Down (Korean Patent Registration No. 10-0971736)”) by the present inventor, an order of constructing on the construction site is as follows. A mold for constructing the slab is formed, and the lower main reinforcing bar and the sub reinforcing bar are installed. Thereafter, the shear reinforcement is installed on the lower reinforcing bar, and the upper main reinforcing bar and the sub reinforcing bar are installed. In contrast, when the shear reinforcement 10 for a reinforced concrete structure according to the present invention is used, the shear reinforcement 10 is installed after the lower and upper reinforcing bars are arranged, as shown in FIG. 7.

Accordingly, the shear reinforcement 10 for a reinforced concrete structure according to the present invention can improve the work convenience while maximizing shear reinforcing performance of the shear reinforcement proposed in the previous application by the present inventor.

In accordance with the shear reinforcement for a reinforced concrete structure according to the present invention, since the shear reinforcement of the present invention is inserted into the arranged reinforcing bars, the shear reinforcement 10 is installed after the arrangement is finished at the time of constructing the reinforced concrete unlike the shear reinforcement proposed in the previous application filed by the present inventor, so that it is possible to improve the convenience of the arrangement.

Further, in the shear reinforcement for a reinforced concrete structure according to the present invention, since the upper anchor head 22, the lower anchor head 24 and the connecting plate 26 are formed using the rectangular plates 22′, 24′ and 26′ made of the flat metal material and are fused to each other through welding to form the reinforcement bracket 20, it is possible to economically produce shear reinforcements of various standards required in a variety of construction sites with ease.

SHEAR REINFORCEMENT FOR REINFORCED CONCRETE STRUCTURE

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