Prefabricated cage system for reinforcing concrete members
A device for reinforcing concrete. The device includes a perforate load-bearing member with first and second surfaces around which concrete can be placed. Apertures in the perforate load-bearing member form connectivity points between concrete disposed on the first and second surfaces to promote bonding of the concrete such that a contiguous mass of concrete forms upon curing. The resulting reinforced concrete structure is of integral construction. In one embodiment, the device can be configured as cage-like structure. In addition, the device may define a unitary structure that can be prefabricated, thereby reducing the time and cost of formation of a reinforced concrete structural member.
This application claims the benefit of U.S. Provisional Application Ser. No. 60/500,885, filed Sep. 5, 2003.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENTThis invention was supported by the government under Contract No. CMS-0355321 awarded by the National Science Foundation (NSF). The government has certain rights in the invention.
BACKGROUND OF THE INVENTIONThe present invention generally relates to reinforcement for use in building structures, and more particularly to concrete reinforcement that forms a structure with concrete to perform the role of both longitudinal and lateral reinforcement.
The use of reinforced concrete members is well-known in the building art. Some of steel's outstanding properties, such as high tensile strength, high ductility and availability are combined with concrete's beneficial properties, including high compressive strength, good formability, low cost and high temperature and fire resistance. Combinations employing these two materials are a good choice for designing members used in bridges, tunnels, stadiums, multistory commercial and residential dwellings and related structures, hereinafter collectively referred to as buildings or building structures. Examples of steel/concrete combinations used in building structures include conventional reinforcing bar (rebar) reinforced concrete systems, concrete-filled tubular systems, steel-concrete composite systems, and welded wire fabric systems.
Typical rebar-based systems employ cylindrical steel rebar interlocked into a skeletal frame inside a concrete matrix. In such systems, steel rebar is used for carrying the tensile stresses and improving member ductility. The rebar is usually used as longitudinal and lateral (transverse) reinforcements in such systems for columns, beams and other related reinforced concrete structures. The process of arranging numerous longitudinal and transverse reinforcement with tie wires into a skeletal frame, then placing forms around the frame pouring concrete into the interstices is labor intensive, and hence expensive. Moreover, the complexity of such systems increases the likelihood of loose tolerances and related lowering of load-carrying capacity.
In steel-concrete composite systems, steel profiles (for example, I-beams) are placed inside the member to provide higher axial strength. This system helps provide a high strength in a relatively small cross-sectional area to avoid the limitations of traditional rebar-based systems, where the spacing of the bars in a relatively small section may be less than the allowable amount. Composite sections are usually used in high rise buildings, where a high axial strength with the minimum area provided for columns are desirable. The concrete cover protects the steel against fire, moisture and other environmental elements. The high metal reinforcement ratio, as well as its placement near the center of the reinforced concrete member, may result in a relatively inefficient system with limited ductility, flexural and torsional resistance.
In the concrete-filled tubular system, a hollow steel section like a pipe or a rectangular box is filled with concrete. This system is useful especially when very high axial strength and concrete confinement with the least cross-sectional area is desirable. One of the chief attributes of the tubular system is its efficiency of structure, where the tensile strength is mainly provided by the steel, which is at the outer most level from the center. Nevertheless, because the steel is situated at the outermost portion of the system, it is exposed and therefore subject to fire and corrosion damage.
In the welded wire fabric system, a prefabricated wire steel system is used for carrying the tensile stresses. In the welded wire system, steel wires/bars are laid in two perpendicular directions and are welded at intersections using rollers and roll welding process. This system is usually used for providing reinforcements in planar sections such as tunnels and shear walls. The steel wires are usually the same in diameter and spacing in both directions, but they can be produced to be different in the two directions.
What is needed is reinforcement for concrete structures that can satisfy the stringent load-carrying and environmental requirements of building components. What is additionally needed is such reinforcement that is easy and inexpensive to fabricate and allows for fast construction.
SUMMARY OF THE INVENTIONThese needs are met by the present invention, where a reinforcement for reinforced concrete members is disclosed. While it is understood that the present invention reinforcement is applicable to various concrete structural members (as will be discussed in more detail below), much of the following discussion takes place in the context of a reinforced concrete column. Deviations from column-particular features will be apparent from the context.
In a first aspect of the invention, a concrete reinforcing device made up of a perforate load-bearing member having first and second surfaces is disclosed. The device is configured to accept concrete such that upon pouring concrete around the surfaces, apertures that give the load-bearing member its perforate nature allow concrete from the first and second surfaces to contact and bond, thereby forming a contiguous mass of the concrete. This creates an interlocked relationship between the device and the concrete such that an integral structure is formed.
Optionally, the material making up the device is a metal or metal alloy. In a preferred embodiment, the device is made from steel. In another option, the device is of unitary (i.e., one-piece) construction such that longitudinal and lateral reinforcements (also referred to as longitudinal and lateral reinforcement stripes) are defined by the apertures formed in the device. These reinforcements, by defining the portion of the device that remains upon formation of the apertures, are substantially coplanar with the portions of the first and second surfaces that define the reinforcement. The unitary construction of the present invention can be used to perform the role of both longitudinal and transverse reinforcement in rectangular and circular reinforced concrete columns without the need for supplemental, assembled components, such as rebar, tie wires, welded wire fabric or disparate composite members. Inherent in the unitary construction of the device is that the intersections of longitudinal and lateral reinforcement stripes define a continuous and uninterrupted structure.
The device may be formed in either a substantially two-dimensional (i.e., planar) or three-dimensional shape. In one particular three-dimensional embodiment, the device is configured as a cage such that the first surface is substantially inward facing and the second surface is substantially outward facing. Regardless of whether the device is configured to be planar, cage-shaped or some shape in-between, the apertures can be arranged in a substantially repeating pattern (such as along rows and columns), and may be formed in numerous preferred shapes, such as rectangles (with or without rounded corners), circles or the like. It will be appreciated by those skilled in the art that apertures formed from rectangular or related sharp-cornered shapes can be rounded to reduce stress concentration in corners. In one embodiment, all of the apertures are substantially similar in size, while in another, they can be of various sizes. In this latter configuration, larger apertures can be used near the middle portion of the reinforcing device used as column reinforcement, where less transverse reinforcement is required, while the dimensions of the apertures can be reduced with less spacing near the top and bottom of the device to promote enhanced shear strength under high lateral load conditions. As the amount of transverse reinforcement is increased by using smaller spacing, the shear resistance of that part of the column also increases.
According to another aspect of the invention, a reinforced concrete structure is disclosed, including a concrete reinforcing device comprising a perforate load-bearing member having a first surface and a second surface, and a mass of concrete coupled with the perforate load-bearing member such that apertures defining the perforate load-bearing member facilitate bonding between a portion of the mass of concrete disposed on the first surface and a portion of the mass of concrete disposed on the second surface. As with the first aspect discussed above, this cooperation made possible by the perforate load-bearing member results in an integral structure between the mass of concrete and the device.
Optionally, the perforate load-bearing member comprises a cage into which the portion of the mass of concrete disposed on the first surface is placed, and outside of which the portion of the mass of concrete disposed on the second surface is formed. Where a large and heavily reinforced concrete structural member cross-section is required, two or more cages of differing size can be placed concentrically to provide the required reinforcement. The structural member may be (among other things) a column, beam, pile, shear wall, retaining wall, foundation, slab or joint between a column and beam. In addition, the device can be used as the whole or as part of the necessary reinforcement for the reinforced concrete structure. It will be appreciated by those skilled in the art that other applications involving the use of reinforced concrete members are possible. For example, any beam or column-like member such as a tapered bridge pier, pier with interlocked reinforcement, and coupling beams can be reinforced with the system of the present invention. Furthermore, the system of the present invention can also be used in uncommon structural components, such as precast folded plates and reinforced concrete shell structures.
According to another aspect of the invention, a reinforced concrete column is disclosed. The column includes a perforate load-bearing metal cage and a concrete mass cooperative with the cage. The cage is of unitary construction, and is configured such that it has at least an inward-facing first surface and an outward-facing second surface. The apertures defined in the cage (i.e., that give the cage its perforate attributes) form a channel through which concrete can flow and ultimately cure such that upon such curing facilitates bonding between a portion of the mass disposed on the first surface and a portion of the mass disposed on the second surface to effect an integral structure between the mass and the cage. Optionally, the apertures are substantially circumscribed by transverse and longitudinal reinforcements that are formed into and make up the lattice-like structure of the cage. The apertures and one side (for example, the inward-facing side) of the reinforcements define the first cage surface, while the apertures and an opposing side (for example, the outward-facing side) of the reinforcements define the cage second surface.
According to another aspect of the invention, a method of reinforcing a building is disclosed. The method includes configuring at least one load-bearing structure and placing it in a position in the building such that it carries at least a portion of a structural load in the building. The load-bearing structure includes a concrete reinforcing device comprising a perforate member having a first surface and a second surface, and a mass of concrete cooperative with the perforate member such that apertures defining the perforate load-bearing member facilitate bonding between a portion of the mass of concrete disposed on the first surface and a portion of the mass of concrete disposed on the second surface to form an integral structure between the mass of concrete and the device. Optionally, the perforate member is generally cage-shaped, and can be of unitary construction.
According to yet another aspect of the invention, a method of making a concrete column is disclosed. The method includes configuring a load-bearing metal cage to have at least an inward-facing first surface and an outward-facing second surface such that a plurality of apertures defined between the first and second surfaces define numerous channels, flowing a concrete mass onto the cage, and curing the concrete mass. During placement of the concrete, a portion of the mass forms substantially against the first surface, a portion of the mass forms substantially against the second surface and a portion of the mass forms in the channels defined by the apertures. The presence of a concrete portion in the channels promotes connectivity between the concrete portions placed against the first and second cage surfaces, and results in a substantially contiguous concrete structure that is formed around the cage. Once the concrete cures, it forms a rigid concrete mass around the cage. Optionally, forms can be placed around the cage prior to the flowing the concrete mass in order to give the column a predetermined shape. After the concrete has cured, the forms can be removed. In another option, the columns can be either formed in a substantially horizontal position such that upon concrete curing can then be lifted into place, or formed in situ.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGSThe following detailed description of the preferred embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
Referring first to
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Referring with particularity to
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There are at least three possible methods for fabricating the apertures 140 into cage 110. In one method, a punching system can be used to punch the apertures 140 into the plate. The thickness of the plate, size of the apertures 140, and the distance between adjacent horizontal and vertical apertures 140 can be made to vary depending on the longitudinal and transverse strength needs. In a second method, the apertures 140 can be cast directly into the plate, where melted steel is cast through a framework in the shape of the cage 110. This approach has the advantage of allowing the cage 110, including the apertures 140 to be cast in multiple shapes, including cylinder or box shapes, avoiding the necessity of performing additional steps such as shaping, forming, cutting or welding. In yet another method, various cutting approaches, such as laser, flame, plasma, abrasive jet, electrochemical machining, electrical discharge machining, milling or related automated or semi-automated schemes, can be used to form apertures 140. The choice of which of the different methods to use is driven by various factors, including cost, quantity, need for precision, finished product or the like. Producing various cages 110 with different thicknesses and different aperture 140 sizes is possible and easy with these methods.
Column 100 has additional advantages over the traditional rebar system of
The inherent rigidity and structural continuity enabled by the unitary construction of cage 110 results in very efficient transfer of loads between the longitudinal and transverse reinforcements 120, 130. This helps provide a higher load-carrying capacity with the same amount of steel, resulting in a more efficient use of the longitudinal reinforcement 120. As previously mentioned, such a configuration also eliminates weak points in the cage 110 due to the mistakes in construction as well as decreasing the time spent assembling it. In addition, tailored structural properties are easily integrated into the device (whether in plate or cage form), as the dimensions and spacing of the apertures 140 need not be the same over the height of the column 100.
The confinement provided by the cage 110 of
Referring next to
Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. More specifically, although some aspects of the present invention are identified herein as preferred or particularly advantageous, it is contemplated that the present invention is not necessarily limited to these preferred aspects of the invention.
Claims
1. A concrete reinforcing device comprising a perforate load-bearing member having a first surface and a second surface, said device configured such that upon placement of concrete in cooperative arrangement with said surfaces, apertures defining said perforate load-bearing member facilitate bonding between concrete disposed on said first and second surfaces to effect contiguous mass of said concrete that forms upon curing an integral structure with said device.
2. The device of claim 1, wherein material making up said device comprises a metal.
3. The device of claim 1, wherein said device is of unitary construction.
4. The device of claim 1, wherein said device is configured as a cage such that said first surface is substantially inward facing and said second surface is substantially outward facing.
5. The device of claim 1, wherein said apertures defined in said device are arranged in a substantially repeating pattern.
6. The device of claim 5, wherein said apertures are substantially rectangular in shape.
7. The device of claim 5, wherein all said apertures are substantially similar in size.
8. The device of claim 5, wherein said apertures comprise a plurality of sizes.
9. The device of claim 1, wherein said apertures are substantially circumscribed by a plurality of transverse reinforcements and a plurality of longitudinal reinforcements such that said apertures and one side of said reinforcements define said first surface of said load-bearing member while said apertures and an opposing side of said reinforcements define said second surface of said load-bearing member.
10. The device of claim 9, wherein said lateral and longitudinal reinforcements are substantially coplanar with one another within each of said surfaces of said load-bearing member.
11. A reinforced concrete structure comprising:
- a concrete reinforcing device comprising a perforate load-bearing member having a first surface and a second surface; and
- a concrete mass cooperative with said perforate load-bearing member such that apertures defining said perforate load-bearing member facilitate bonding between a portion of said mass disposed on said first surface and a portion of said mass disposed on said second surface to effect an integral structure between said mass and said device.
12. The structure of claim 11, wherein said load-bearing member comprises at least one perforate cage into which said portion of said mass disposed on said first surface is placed.
13. The structure of claim 12, wherein said structure is a column.
14. The structure of claim 13, wherein said column comprises a substantially cylindrical shape along its longitudinal axis.
15. The structure of claim 13, wherein said column comprises a substantially rectangular shape along its longitudinal axis.
16. The structure of claim 12, wherein said structure is a pile.
17. The structure of claim 14, wherein said pile comprises a substantially cylindrical shape along its longitudinal axis.
18. The structure of claim 12, wherein said perforate load-bearing member comprises a plurality of cages each of which sized to facilitate concentric placement of said plurality of cages into said mass of concrete.
19. A reinforced concrete column comprising:
- a perforate load-bearing metal cage having at least an inward-facing first surface and an outward-facing second surface, said cage comprising a unitary construction; and
- a concrete mass cooperative with said cage such that apertures defined in said cage facilitate bonding between a portion of said mass disposed on said first surface and a portion of said mass disposed on said second surface to effect an integral structure between said mass and said cage.
20. The column of claim 19, wherein said apertures are substantially circumscribed by a plurality of transverse reinforcements and a plurality of longitudinal reinforcements such that said apertures and one side of said reinforcements define said first surface of said load-bearing member while said apertures and an opposing side of said reinforcements define said second surface of said cage.
21. A method of reinforcing a building, said method comprising:
- configuring at least one load-bearing structure to comprise: a concrete reinforcing device comprising a perforate member having a first surface and a second surface; and a mass of concrete cooperative with said perforate member such that apertures defining said perforate member facilitate bonding between a portion of said mass of concrete disposed on said first surface and a portion of said mass of concrete disposed on said second surface to effect an integral structure between said mass of concrete and said perforate member; and
- placing said load-bearing structure in a position in said building such that it carries at least a portion of a structural load of said building.
22. The method of claim 21, wherein said perforate member is configured as a cage.
23. The method of claim 22, wherein said cage is of unitary construction.
24. A method of making a concrete column, said method comprising:
- configuring a load-bearing metal cage to have at least an inward-facing first surface and an outward-facing second surface such that each of a plurality of apertures defined between said first and second surfaces defines a channel therebetween; and
- flowing a concrete mass onto said cage such that a portion of said mass forms substantially against said first surface, a portion of said mass forms substantially against said second surface and a portion of said mass forms in said apertures such that a substantially contiguous concrete structure is formed by said mass around said cage; and
- curing said concrete mass.
25. The method of claim 24, further comprising placing forms around said cage prior to said flowing said concrete mass such that upon said flowing said concrete mass, a layer corresponding to said mass forming substantially against said second surface becomes substantially bounded by said outward-facing second surface and said form.
26. The method of claim 25, further comprising removing said forms from said column once said concrete has cured.
Type: Application
Filed: Sep 2, 2004
Publication Date: Mar 17, 2005
Inventors: Mohammad Shamsai (Westerville, OH), Halil Sezen (Columbus, OH)
Application Number: 10/932,560