REINFORCEMENT SHEAR CONTROL SYSTEM

Abstract: A system of shear control reinforcement for use in a reinforced concrete structure comprising one or more shear control members (3) bent into a substantially rectangular wave formation; the shear control member (3) being unitary and continuous for at least 1.5 wave cycles and being adapted to restrain conventional main tension control reinforcement elements (2) placed substantially transversely thereto and against the shear control member (3) adjacent a point of maximum amplitude but within the wave configuration.

Description: REINFORCEMENT SHEAR CONTROL SYSTEM The invention relates to a shear control system for reinforced concrete structures and to a method of placement of reinforcement in order to achieve desired shear control. With any reinforcement system in concrete structures there are the main reinforcement elements which control the tension forces and to a lesser extent the compression forces. There is also often need to control shear forces occurring within the structure. These forces are controlled by shear reinforcement elements. Shear reinforcement elements are typically placed substantially perpendicular to the main reinforcement elements with a view to preventing these main reinforcement elements moving away from each other under the influence of shear forces in the structure. Existing arrangements of reinforcement and the shear elements in structures has, to a large extent, been an add on feature after the main reinforcement has been designed and placed in position. This has had the effect of adding a large number of individual items needing to be fixed in the construction process. Accordingly the objective of the present invention is to provide a reinforcement shear control system adapted to reduce the number of elements comprising the reinforcement structure whilst providing effective shear control or at least to provide the market with an alternative. According to the present invention there is disclosed a shear reinforcement system for a reinforced concrete structure comprising one or more shear control members bent into a substantially rectangular wave formation; the shear control members being unitary and continuous for at least l.S wave cycles and being adapted to restrain conventional main tension control reinforcement elements placed substantially transversely thereto and against the shear control reinforcement adjacent a point of maximum amplitude but within the wave configuration. A number of embodiments of the present invention will now be described with reference to the accompanying drawings in which: Figures la, lb and lc are sectional views of conventional reinforcing systems; Figures Id and le are sectional views of the reinforcement shear control system in accordance with the present invention; Figures 2a and 2c are sections through alternate conventional shear reinforcement systems; Figures 2b and 2d are sectional views through reinforcement shear control systems in accordance with the present invention; Figure 3 a is a section through a conventional shear reinforcement system in a continuous run situation such as a wall or flat slab; Figure 3b is a section through shear control reinforcement in accordance with the present invention applied to a continuous run such as a wall or flat slab; Figure 4a is a perspective view of multiple parallel rows of shear reinforcement in accordance with the present invention and associated main tension control reinforcement as would be used in relation to a conventional slab; Figure 4b is a side elevation of one row of shear reinforcement from the grid of figure 4a; Figure 5 is a top plan view of a shear control system in accordance with the present invention with a series of shear control elements and main tension control reinforcement all running at right angles to each other; Figure 5a is a section through A-A' of figure 5 and figure 5b is a section through B-B' of figure 5. In the embodiments depicted in the various figures herewith the conventional shear reinforcement elements are indicated by the reference numerals 1 with the main reinforcement adapted to control tension in the reinforced concrete structure being indexed by the numerals 2 and the wave pattern shear control reinforcement elements in accordance with the present invention being indexed by numerals 3. It will be noted that throughout the drawings the shear reinforcement 3 in accordance with the present invention takes the form of a rectangular wave pattern although the wave length is not necessarily constant with respect to the amplitude having regard to the fact that the top and bottom main tension control steel in any given structure may have a different spacing than that spacing between each element of main tension control steel and its adjacent element. As will be evident from figure 2b it may be desirable that the wave length of the shear control system in accordance with the present invention may not be constant. Figure 2b depicts a situation where the wave length of every other half wave is twice as long as the preceding wave length. It will be appreciated from figure 3b that the placement of top steel 2a and bottom steel 2b is not exactly as would be the case in the conventional arrangement depicted in figure 3a. This is due to the fact that in order to work in the best possible manner the main tension control steel elements are placed against the internal corners of the square wave function shaped shear reinforcement in accordance with the present invention. This results in the top steel 2a not being directly above the corresponding bottom steel element 2b as is clear from figure 2b. Top steel elements 2a are actually staggered with respect to bottom steel elements 2b in the embodiment of the present invention depicted in figure 3b. With reference to figure 5 there is depicted a rectangular grid of steel reinforcement elements in accordance with the present invention. It will be noted that only the tops of the shear control elements in accordance with the present invention are depicted in solid lines with the top 2a and bottom 2b linear main tension control steel elements being depicted in broken lines. As both the main tension control steel elements (top and bottom) are placed in a series of rows and columns at right angles to each other in the conventional fashion (except that they are staggered as hereinbefore described) the regular square wave form shear control members 3 in accordance with the present invention are likewise placed in a series of parallel rows and parallel columns (the columns being at ninety degrees to the rows). The heights of the various steel elements with respect to each other are readily apparent from figures 5a and 5b. It will be noted from figures 5a and 5b that the shear control steel in accordance with the present invention never protrudes much more than one diameter of reinforced steel bar above the outermost main tension control reinforcing bar. It will be appreciated by those skilled in the art that placement of the shear reinforcement in accordance with the present invention should occur prior to placement of the main tension control reinforcement in any given structure in order that the main shear control steel may be placed in the most advantageous position with respect to the shear control reinforcement. This most advantageous position is the internal corners of the rectangular wave structure of the shear control reinforcement in accordance with the present invention. The drawings herewith depict shear reinforcement in accordance with the present invention being utilised in respect of planer articles. It should be appreciated that concave, convex or even circular articles may be formed utilising shear reinforcement in accordance with the present invention and in such cases the imaginary axis along which the rectangular wave form of the shear reinforcement would proceed would no longer be linear but would itself be curved. It will furthermore be appreciated that the continuous nature of the square wave form shear control reinforcement of the present invention results in easy handling and a vast reduction in the number of shear control elements required particularly in relation to large structures such as slabs.

Claims: The claims defining the invention are as follows: 1. A system of shear control reinforcement for use in a reinforced concrete structure comprising one or more shear control members bent into a substantially rectangular wave formation; the shear control member being unitary and continuous for at least 1.5 wave cycles and being adapted to restrain conventional main tension control reinforcement elements placed substantially transversely thereto and against the shear control reinforcement adjacent a point of maximum amplitude but within the wave configuration. 2. A shear control reinforcement system in accordance with claim 1 hereof wherein the main tension control reinforcement elements are placed against the shear reinforcement element or elements at the internal corners defined by the square wave configuration of the shear reinforcement pattern. 3. A shear control reinforcement system in accordance with claim 1 hereof wherein there are two or more substantially parallel shear control elements each being unitary and continuous for at least 2.0 wave cycles and being in register such that conventional tension control reinforcement elements may pass transversely through both shear control elements abutting each shear control element in a like position with respect to the square wave pattern. 4. A shear control reinforcement system in accordance with claim 3 hereof wherein there are two sets of shear reinforcement; one as described with reference to claim 3 hereof and another like set placed perpendicular thereto with the uprights of each set of shear reinforcement abutting each other and the configuration in plan view being such that the tops of the waves form rectangles; the tops of the waves of one set of shear reinforcement being slightly above those of the other set so as to accommodate placement of both top and bottom main tension control reinforcement elements in a conventional rectangular grid-type configuration. 5. A method of placement of shear control reinforcement of the type disclosed in claim 1 hereof wherein the shear control reinforcement is located in position prior to the placement of the main tension control reinforcement. 6. A shear control reinforcement system in accordance with claim 3 hereof wherein the wave length of the shear reinforcement member is constant. 7. A shear control reinforcement system in accordance with claim 3 hereof wherein the wave length of the shear reinforcement member alternates between two different wave lengths. 8. A shear control reinforcement system in accordance with claim 3 hereof wherein the wave length of the shear reinforcement member is variable. 9. A shear control reinforcement system in accordance with any one of claims 1 to 5 hereof wherein the shear reinforcement is fabricated from conventional steel bar. 10. A shear control reinforcement system in accordance with claim 3 hereof wherein the shear control members have a rectangular wave form which proceeds along a substantially linear axis. 11. A shear control reinforcement system in accordance with claim 3 hereof wherein the shear control members have a rectangular wave form which proceeds along a curved axis. AMENDED CLAIMS [received by the International Bureau on 26 November 1997 (26.11 .97) ; original claims 1 and 2 amended; remaining claims unchanged (3 pages) ] 1. A system of shear control reinforcement for use in a reinforced concrete structure comprising one or more shear control members bent into a substantially rectangular wave formation; the shear control member being unitary and continuous for at least 1.5 wave cycles and being adapted to restrain two or more conventional main tension control reinforcement elements placed substantially transversely thereto; at least a first main tension control reinforcement element lying against the shear control reinforcement adjacent a point of maximum amplitude and at least a second such tension control reinforcement element lying against a point of minimum amplitude; at least the first and second main tension control reinforcement elements lying within the wave configuration. 2. A shear control reinforcement system in accordance with claim 1 hereof wherein the main tension control reinforcement elements are placed against the shear reinforcement element or elements at the internal corners defined by the square wave configuration of the shear reinforcement pattern. 3. A shear control reinforcement system in accordance with claim 1 hereof wherein there are two or more substantially parallel shear control elements each being unitary and continuous for at least 2.0 wave cycles and being in register such that conventional tension control reinforcement elements may pass transversely through both shear control elements abutting each shear control element in a like position with respect to the square wave pattern. 4. A shear control reinforcement system in accordance with claim 3 hereof wherein there are two sets of shear reinforcement; one as described with reference to claim 3 hereof and another like set placed perpendicular thereto with the uprights of each set of shear reinforcement abutting each other and the configuration in plan view being such that the tops of the waves form rectangles; the tops of the waves of one set of shear reinforcement being slightly above those of the other set so as to accommodate placement of both top and bottom main tension control reinforcement elements in a conventional rectangular grid-type configuration. 5. A method of placement of shear control reinforcement of the type disclosed in claim 1 hereof wherein the shear control reinforcement is located in position prior to the placement of the main tension control reinforcement. 6. A shear control reinforcement system in accordance with claim 3 hereof wherein the wave length of the shear reinforcement member is constant. 7. A shear control reinforcement system in accordance with claim 3 hereof wherein the wave length of the shear reinforcement member alternates between two different wave lengths. 8. A shear control reinforcement system in accordance with claim 3 hereof wherein the wave length of the shear reinforcement member is variable. 9. A shear control reinforcement system in accordance with any one of claims 1 to 5 hereof wherein the shear reinforcement is fabricated from conventional steel bar. 10. A shear control reinforcement system in accordance with claim 3 hereof wherein the shear control members have a rectangular wave form which proceeds along a substantially linear axis. 11. A shear control reinforcement system in accordance with claim 3 hereof wherein the shear control members have a rectangular wave form which proceeds along a curved axis.

Inventors: WYLIE JOHN HAMILTON MAULSDEN, WYLIE, JOHN, HAMILTON, MAULSDEN
Applicants: IRONBARKS SYSTEMS PTY LTD, WYLIE JOHN HAMILTON MAULSDEN, IRONBARKS SYSTEMS PTY. LTD., WYLIE, JOHN, HAMILTON, MAULSDEN
Application year: 1997
Main classification: E04C5
IPC codes: E04C5