REINFORCEMENT FOR REINFORCED CONCRETE AND METHODS FOR M NUF CTURING THEREOF

Cross- Reference to Related Appiications

1000 Ij This application claims benefit of priority under 35 U.S.C. 119(e) to Provisional Application No. 61/697,574 filed September 6, 2012 and incorporated by reference herein.

Technical field

[0002] The present disclosure relates generally to field of construction materials and, particularly, to reinforcement for precast and monolithic reinforced concrete structures.

Background

{0003] Reinforced concrete is a popular construction material, it typically uses embedded reinforcement structures that have high tensile strength and ductility to reinforce concrete,.

{0004] One popular type of reinforcement is a steel reinforcement bar (i.e. rebar). A rebar may be a hot-roiled or cold-drawn metal rod with circular cross section and ribbed surface. The ribs erfhance bonding between the rebar and concrete. However, due to small height of the ribs, the bonding between the ribs and concrete can break under the stress, causing slipping of the rebar inside concrete, which weakens the concrete. To obtain the necessary tensile strength of the reinforcement, the number of rebars must be increased, which adversely increases weight of the reinforcement and cost of construction of the reinforced concrete.

{0005] Another popular type of reinforcement may be manufactured from tubular blanks with hot-rolled corrugated ribs. This manufacturing method provides a reduced weight of the reinforcement. However, such a tubular reinforcement structure typically cannot be made with a diameter less than 20 mm. Furthermore, the economic gain is insignificant, due to the increased complexity and energy intensity in the manufacturing of such a reinforcement. {0006] Another type of reinforcement is a cable reinforcement, which includes several metal wires wound into strands. This type of reinforcement structure provides a more effective reinforcement than the rebars, but has much higher cost of manufacture.

[0007j Thus, there is a need for an improved reinforcement for reinforced concrete, which has lower weight and lower cost of manufacture then the known types of reinforcements.

Summary

[0008] Disclosed herein a reinforcement structure for reinforced concrete and methods of manufacturing thereon. In one example aspect of the invention, a reinforcement structure includes a rod comprising a spiral strip having a pitch between 1.0 and 10.0 times the width of the strip and a ratio of thickness of the strip to the width of the strip in a range of 1:4 to 1:10.

{0009] in another example aspect, the edges of the spiral strip may be rounded.

{0010] In another example aspect the surface of the spiral strip may he entirely or partially corrugated with ribs of arbitrary shape, such as straight, reticular, or pointed ribs.

[0011] in various example aspects, the height of the ribs may be in a range of 0.05% to 0.30% of the th ickness of the strip.

{0012] In another example aspect the spiral may have a regular or an irregular pitch.

[0013] In another example aspect, the spiral may comprise a mortofi!ar or muitifilar helix.

{0014] In yet another example aspect of the invention, a method for manufacturing a monofilar reinforcement structure comprises flattening a wire rod into a f!at strip, corrugating the fiat strip with ribs, and twisting the ribbed strip into a spiral of having a specified pitch. {0015] In yet another example aspect of the invention, a method for manufacturing a muitifilar reinforcement for reinforced concrete comprises extruding a star-shaped contour having a plurality of rays, each ray including a flat strip, wherein a ratio of thickness of a strip to 3 width of the strip in a range of 1 :4 to 1:10; twisting the piuraiity of strips 3 into a multifi!ar spiral having a pitch between 1.0 and 10.0 times the width of the strip; and concurrently with twisting, corrugating on each of the strips ø piuraiity of ribs having height in a range of 0.05% to 0,30% of the thickness of the strip.

10016] The above simplified summary of example aspects of the invention serves to provide a basic understanding of the invention. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or criticai elements of all aspects nor delineate the scope of any or ali aspects of the invention, its sole purpose is to present one or more aspects in a simplified form as a prelude to the more detailed description of the invention that follows, To the accomplishment of the foregoing., the one or more aspects of the present invention comprise the features described and particularly pointed out. in the claims.

Brief Description of the Drawings

{00 /J The accompanying drawings,, which are incorporated into and constitute a part of this specification, illustrate one or more example aspects of the invention and, together with the detailed description, serve to explain their principles and implementations.

Fig. 1 illustrates a genera! view of a reinforcement structure for reinforced concrete in accordance with aspects of the present invention.

Figs. 2 and 3 illustrate a process of manufacturing the reinforcement structure from a wire rod in accordance with aspects of the present invention.

Detailed Description

{0018] Disclosed herein are example aspects of a reinforcement structure for reinforced concrete and methods for manufacturing thereof. Those of ordinary skii! in the art will realize that the foiiowing description is iilustrative only and is not intended to be in any wa limiting. Other aspects will readily suggest themselves to those skilled in the art having the benefit of this disclosure. Reference wili now be made in detail to implementations of the example aspects as Illustrated in the accompanying drawings. The same reference indicators will be .used throughout the drawings and the following description to refer to the same or like items.

[0019] Fig. ί illustrates a general view of a reinforcement structure for reinforced concrete in accordance with one aspect of the present invention. As shown, the reinforcement structure includes a rod 10 comprising a spiral strip 11, which is twisted into a monofilar or muitifiiar helix along a longitudinal axis 13 of the strip 11, The spirai strip II. has diameter (8) and thickness (t).

[0020] In various aspects, the spiral may have, regular or irregular pitch (T) _: , which may vary {or be constant) between about 1.0 and 10.0 times of the diameter |B) of a cylinder into which the spiral is inscribed, in soother aspect, a ratio of the thickness (t) of the strip 11 to its diameter fS) may be in the range of about 1:4 to 1:10. in various aspects, the spiral strip 11 may comprise a monofiiar helix or a muitifiiar elix, such as a double or triple helix. In various aspects, the rod 10 may be made of steel, metal or plastic, such as composite plastic,

[0021] i one aspect, the one or more surfaces of the spirai strip li may be completely o partially corrugated with ribs 12 of arbitrary shape. Sn various aspects, the ribs 12 may he straight, reticular or pointed in shape. In various aspects, the ribs 12 may be transverse fas shown) or longitudinal is direction, in one aspect, the height of the ribs 12 above th surface of the strip 11 ma be between 0.05 and 0.30% of the thickness ft) of the spiral strip 11,

[0022] One advantage of the spirai reinforcement structure is a reduction in the overall mass of the reinforcement. ^' while preserving firmness of the reinforced concrete, which attributed to a fuller utilization of the firmness of both the concrete and reinforcement;

[00.23] For example, the spiral reinforcement structure has substantially smaller mass than rebar-type reinforcement with equal resistance of the reinforced concrete structure to bending,

[0024] Another advantage of the spirai reinforcement structure is that is provides a significant increase in the contact, surface between the reinforcement structure and the surrounding concrete materia! and, consequently, an increase in the load that the reinforced concrete can withstand with help of the reinforcement structure without failing.

[0025] An advantage of having ribs on the surface of the spirai reinforcement structure is that they prevent an "unscrewing" ^' of the reinforcement structure from concrete under load.

[0026] An advantage of rounding of the edges of the spiral reinforcement structure is that it prevents concentration of stress in concrete at the point of contact with the reinforcement.

[0027] it should be a!so noted that a reinforced concrete that incorporates the described spirai reinforcement structure has the same strength as a reinforced concrete that incorporates a rebar-type reinforcement having equal cross-section diameter. For example, the Moldavian Scientific Research institute for Construction "i CERCO " carried out investigations on the reinforced concrete samples with a size of 160x40x40 mm with respect to their resistance to bending. The results of the investigations are presented in the table below:

fOCT p 52544-2006 is a set of specifications of weidabie deformed reinforcing roiled products of classes A500C and 8500C for reinforcement of concrete constructions. These specifications ca be obtained on the following website: http://www.gostheip,ru/gost/gostl878.html. {0028] As can be seen from the table, a spiral reinforcement rod with dimensions of 7,8 X 3 mm may has a comparable strength to a rebar with a cross section diameter {0} of 8 mm. The slight difference in strength of these two reinforcements is due to the difference in the size of the diameter of the rebar and the diameter of the cylinder into which the spiral is inscribed.

{0029] Thus,, to achieve the same strength as the rebar with diameter of 8 mm {a cross- section of which is inscribed in a circle 093 mm), a monoftiar spiral reinforcement with cross-section of 9,3 x 3,2 may be used. Such a spiral reinforcement may be manufacture from a wire rod of 6.5 mm in diameter using, for example, methods described herein below.

{00303 Notably, the spiral reinforce entof such a design uses substantial less metal or steel while providing the same strength in comparison to the rebar-type reinforcement,

10031] ft should be also noted that upon destruction of reinforced concrete in test No. 3, the concrete split from the rebar-type reinforcement in large pieces, while in tests Nos. 1 and 2 the concrete remained hanging from the spiral reinforcement.. This indicates that in the event of failure of building elements, such as during an earthquake, the use of the spira! reinforcement instead of rebars reduces the risk of death or injury of people from collapsing pieces of concrete.

{0032] in one example aspect, a monofiiar spiral reinforcement structure of Fig. 1 may be manufactured from a wire rod having diameter D as shown in Figs, 2 and 3 Particularly, a metal or steel wire rod 20 ma be flattened, by heating or without, using longitudinal rolling through ribbed rollers, until a cross section of t x B is obtained, where t is the thickness of the resulting strip 11 and B is the width (or diameter} of the strip 11. The flat metal strip 11 may then be twisted into a spiral using known electromechanical or manual twisting devices, in one aspect the pitch (T) of the spiral of strip 11 may be regular or irregular and may vary (or be constant) between about 1,0 and 10.0 times of the diameter f B). In another aspect,, the ratio of the thickness ft) to the diameter (B) of the strip 11 may be in the range of about 1:4 to 1:10. {0033] in another aspect, a monofi!ar spiral reinforcement structure of Fig, 3 may be manufactured from a roiled flat metai (or stee!) strip of specified width (8). Specifically, the strip may be first passed through ribbed rollers, which corrugate ribs on the surfaces of the strip. The edges of the strip may then be rounded by filing or sanding methods. And,, lastly, the ribbed strip may be twisted into a spiral of specified pitch as described in detail above.

{0034] in another aspect, the speed of rotation of the rollers in either of the manufacturing methods may be constant (or varied), and the pitch of the spiral may be varied by continuous regulating of the speed of rotation of the twisting device.

{0035] in yet another aspect, a monofiler or muitifi!ar metal spiral reinforcement structure may be manufactured in a single operation using, for example, a helical transverse roiling of one or more cylindrical blanks,, such as wire rods. In this case, the steps of flattening of the blankfs} and twisting thereof into spiralis} may be performed substantially simultaneously, When a short: blank is used, it may be passed through one or multiple sets of power-driven rollers having ribbed surfaces. When a lon blank is used, it may be manually force-fed through non-motorized rollers, in either case, the rollers may be placed at an angle to the longitudinal axis of the blank. The angle of inclination of the roiiers dictates the pitch of the spiral. When passing through the rollers, the blank is rotated and roiled into a spiral.

{0036] in yet another aspect, a muitifiSar spiral reinforcement structure may be manufactured by extruding from a sheet metal a contour in a shape of a strip or star with multiple rays, each ray comprising a flat strip. The number of rays of the star correspond to the desired number of spirals of the multi filar reinforcement structure. The metai contour may then be passed through a rotating calibrator which flattens the rays to the desired thickness and twists them into the spirals, Concurrently with twisting, the rollers of the calibrator may corrugate ribs of the desired height on one or more of the flattened rays,

10037] In various aspects, the process of manuf acturing the spiral reinforcement structure described herein can he performed using known electro-mechanical rolling and twisting devices operated under the control of a computer programmed with specific program instructions. The program may specify, for example, the thickness of the flat trip, the number of spirals, and the pitch of the spirals, as weii as other relevant configuration parameters. f0038 in the interest of clarity, not ail of the routine features of the aspects are disclosed herein, it will be appreciated that in the development of any actual

implementation of the invention, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, and that these specific goals will vary for different implementations and different developers. It will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.

[0039] Furthermore, It is to be understood that the phraseology or terminology used herein is for the purpose of description and not of restriction, such that the terminology or phraseology of the present specification is to be interpreted by the skilled in the art in light of the teachings and guidance presented herein, in combination with the knowledge of the skilled in the relevant art(s). Moreover, it is not intended for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such.

|0040] The various aspects disclosed herein encompass present and future known equivalents to the known components referred to herein by way of illustration. Moreover, while aspects and applications have been shown and described _, , it. would be apparent to those skilled in the art having the benefit of this disclosure that many more modifications than mentioned above 3re possible without departing from the inventive concepts disclosed herein.