Patent Application
20120137619
This disclosure relates generally to reinforcing structures. More specifically, this disclosure relates to a reinforcing assembly and a reinforced structure (such as reinforced concrete structure) using a reinforcing assembly.
Commercial concrete is a mixture of cement, sand, and stone aggregate that, after the addition of water, slowly hardens together into a rigid structure. Stresses within concrete structures are typically of three primary types: compressive (where particles are crushed together), tensile (where particles are pulled apart), and shear (where one section of a structure is pressured to slide upon an adjacent section).
Unreinforced concrete structures often have good resistance to compressive stresses. However, any significant tensile stresses tend to cause undesirable cracking and separation since concrete is relatively weak in tension. To address this problem, concrete structures are typically reinforced by embedding in place within the rigid structures smaller solid members made of material(s) with high strength in tension. Typically, the smaller members include round steel bars with roughened surfaces, often called “reinforcing steel,” “reinforcing bar,” or “rebar.” Reinforced concrete structures are available commercially in many shapes and sizes, such as slabs, beams, footings, and flat foundations.
Unfortunately, reinforced concrete structures are still highly susceptible to shear forces that create diagonal tensile stresses, which can result in structural failures. Cracking and/or breaking caused by shear forces tend to propagate throughout the stressed zone of a concrete structure. This problem is especially acute in concrete slabs or other supported structures that are supported by columns or other supporting structures. In these types of situations, a slab is subject to a concentration of stresses in a zone near a column, where the column tends to “punch” upward through the slab. The resulting shear forces create diagonal tensile stresses within the supported structure.
For this reason, supported structures are typically reinforced in the areas around columns or other supporting structures. This is done to prevent tensile failure, crack propagation, and consequent structural collapse. However, conventional approaches often provide reinforcement that helps restrain or minimize cracking or breaking only after the cracking or breaking has started. These conventional approaches are typically unable to prevent cracking or breaking from occurring in the first instance.
This disclosure provides a reinforcing assembly and a reinforced structure (such as a reinforced concrete structure) using a reinforcing assembly.
In a first embodiment, a reinforcing assembly includes multiple spaced-apart, longitudinally-extending support bars. The reinforcing assembly also includes multiple working members each independently connected to the support bars. The working members are oriented diagonally with respect to a longitudinal axis extending along the reinforcing assembly.
In a second embodiment, a reinforced structure includes a supported structure and a reinforcing assembly embedded within the supported structure. The reinforcing assembly includes multiple spaced-apart, longitudinally-extending support bars. The reinforcing assembly also includes multiple working members each independently connected to the support bars. The working members are oriented diagonally with respect to a longitudinal axis extending along the reinforcing assembly.
In a third embodiment, a method includes forming a supported structure having a reinforcing assembly positioned within the supported structure. The reinforcing assembly includes multiple spaced-apart, longitudinally-extending support bars. The reinforcing assembly also includes multiple working members each independently connected to the support bars. The working members are oriented diagonally with respect to a longitudinal axis extending along the reinforcing assembly. The diagonally-oriented working members provide diagonal tension shear reinforcement in the supported structure.
Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.
For a more complete understanding of this disclosure and its features, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
The slab structure 101 typically includes internal structural components that provide reinforcement. These internal components can represent any suitable structure(s) formed from any suitable material(s), such as reinforcing bar (“rebar”) 103 formed of carbon steel or other material(s). The rebar 103 can be placed down the length of the slab structure 101 and/or across the width of the slab structure 101. In some embodiments, the rebar 103 extends across the top of the slab structure 101 (into and out of the view as shown), as well as across the bottom of the slab structure 101. However, both may not be needed, such as when rebar 103 is used across only the top of the slab structure 101.
In this example, a load or “reaction” area 104 of the slab structure 101 represents an area where large upward forces can exist, creating punching shear forces in the slab structure 101. Here, the punching shear forces are creating undesirable diagonal tension cracks 105 in the slab structure 101. The cracks 105 can form particularly in areas of high stress of the slab structure 101. Many times, the cracks 105 can form generally in the middle or upper area of the slab structure 101 and can propagate upward and downward, often in a diagonal direction, if not impeded. As described in more detail below, various reinforcing assemblies are disclosed here that can help to reduce or even eliminate the formation of cracks caused by shear forces in a slab structure 101 or other similarly supported structure.
Although
As shown in
As shown in
The “turn-down” created by the hook portion 210 at the top of each working member 204 facilitates near full anchorage along the top of the slab structure 101. At the same time, the hook portion 210 at the top of each working member 204 can ensure that the reinforcing assembly 200 does not block rebar 220 in either direction (the rebar 220 typically is not part of the shear reinforcing assembly 200 itself). This configuration allows the uppermost portions of the working members 204 to extend to a close distance (such as 0.75 inches) from the top surface of the slab structure 101. The bottom of the reinforcing assembly 200 could be the same or similar distance (such as 0.75 inches) from the bottom surface of the slab structure 101. This can allow the working members 204 to engage substantially the full thickness of the slab structure 101 and provide full efficiency.
The central connecting section 216 of each working member 204 connects the upstanding sides 212-214 of that working member 204 to one another so that each working member 204 is an integral unit. The central connecting section 216 therefore provides a stabilizing connection between the two sides of each working member 204.
As noted above, each working member 204 is angled with respect to the support bars 202. More specifically, the upstanding sides 212-214 are angled with respect to the support bars 202. An angle 222 could have any suitable value, such as about 20° to about 70°. In particular embodiments, the angle 222 is about 45°. As shown in
As shown in
The working members 204 can be spaced along the support bars 202 at any suitable fixed or variable distance(s). In
Other progressively-increasing spacings could also be used. For example, each successive spacing away from the column 102 could be a fixed percentage larger than the preceding spacing, and no spacings (except possibly the first few spacings) could be equal. As another example, the spacings could vary incrementally in fractional-inch or other increments. In some embodiments, the smallest spacing between two working members 204 could be about three to about four inches, and the largest spacing between two working members 204 could be about ten inches.
The spacings and the lengths of the working members 204 for any particular installation could be based on various factors. Example factors include the thickness of the slab structure 101, the load to be placed on the slab structure 101, the strength of the concrete or other material(s) forming the slab structure 101, and the size of the column 102. In general, any technique for increasing the spacings between at least some of the adjacent pairs of working members 204 along the length of the reinforcing assembly 200 could be used. Note that the use of smaller spacings closer to the column 102 allows the reinforcing assembly 200 to provide greater reinforcement closer to the support column 102. However, variable spacing is not required in the reinforcing assembly 200.
The following are example values for other dimensions of the reinforcing assembly 200. The reinforcing assembly 200 could have a height 232 of about seven inches to about ten inches. The height 232 could be about 1.5 inches shorter than the height of the slab structure 101, allowing for about 0.75 inches on top and bottom of the reinforcing assembly 200. Each of the working members 204 could have a width 234 on bottom of about 4.25 inches and a width 236 on top of about 3.25 inches. The wider width at the bottom provides stability against overturning and can allow multiple assemblies to be stacked after fabrication (to reduce volume during shipping). Each connecting portion 218 could have a length 237 of about two inches. Each hook portion 210 could form an angle 238 of about 75° and extend downward at a distance 240 of about 2.25 inches. Each hook portion 210 could also have a width 242 of about 3.25 inches and a length 244 of about 3.125 inches. These dimensions are for illustration only.
As shown in
The working members 204 are placed diagonally on the support bars 202 to engage any nascent crack 105 in the slab structure 101 at a 90° or near 90° angle with respect to the crack 105 itself, which provides improved or maximum efficiency in terms of aligning the working members 204 to directly oppose the diagonal tension (splitting) forces. With diagonal placement, each working member 204 traverses a much larger percentage of the potential crack zone per unit length as compared to a vertical orientation. The diagonal placement also enables each working member 204 to engage up to twice as many crack zones per unit. Further, the compact size and alignment of the working members 204 allow the working members 204 to penetrate upward, even between densely-packed top rebar concentrations, and to engage the full depth of structural slab thickness.
Although the use of small (roughened) rebar could mean that more working members are required per installation, this provides an advantage in that it allows a more dispersed distribution of the individual working members in concrete. As a result, the reinforcing can “blend” into the concrete material and act more as an integral part of the concrete itself.
The reinforcing assembly 500 includes multiple support bars 502a-502b (referred to collectively as bars 502) and multiple working members 504. The working members 504 are again oriented diagonally with respect to a longitudinal axis that extends along the support bars 502. Each working member 504 includes an upwardly-extending hook portion 510. Each working member 504 also includes first and second upstanding sides 512-514 and a central connecting section 516 that connects the upstanding sides 512-514. Each upstanding side 512-514 also has a connecting portion 518, which can be welded or otherwise connected to one of the support bars 502. The working members 504 are similar in structure to the working members 204, except the hook portions 510 of the working members 504 are made to hook upward instead of downward.
In this example, each of the support bars 502 can optionally terminate within the support column 102 in a structure 524 that is bent upward. Again, the structure 524 is designed to extend into the support column 102 and provide additional support and gripping action in an area of maximum stress and load transfer.
The following are example values for various dimensions and other characteristics of the reinforcing assembly 500. The support bars 502 and working members 504 can be formed from #3 rebar. The reinforcing assembly 500 could have a height 532 that is about 1.5 inches shorter than the height of the slab structure 101, allowing for about 0.75 inches on top and bottom of the reinforcing assembly 500. The reinforcing assembly 500 could, for example, have a height 532 of about 7.5 inches. Each of the working members 504 could have a width 534 on bottom of about 5.5 inches and a width 536 on top of about 2.5 inches. The upstanding sides 512-514 could be angled at an angle 538 of about 6°, and the hook portion 510 could extend downward at a distance 540 of about 1.5 inches. Each of the connecting portions 518 could have a length 542 of about 1.5 inches.
Once again, the spacings between adjacent working members 504 could be fixed or variable in any suitable manner. For instance, spacings 550-558 could be about 4.125 inches, about 4.375 inches, about five inches, about six inches, and about 7.5 inches, respectively. However, any other suitable spacing(s) could be used.
The reinforcing assembly 700 includes multiple support bars 702a-702b (referred to collectively as bars 702) and multiple working members 704. The working members 704 are again oriented diagonally with respect to a longitudinal axis that extends along the support bars 702. Each working member 704 includes a top portion 708, first and second upstanding sides 712-714, and a central connecting section 716 that connects the upstanding sides 712-714. Unlike the reinforcing assemblies 200 and 500, the working members 704 here lack a longitudinal hook portion, and the top portion 708 is substantially planar with the upstanding sides 712-714. Each upstanding side 712-714 has a connecting portion 718, which can be welded or otherwise connected to one of the support bars 702.
This embodiment of the reinforcing assembly can be simpler to manufacture since the working members 704 require fewer bends than the assemblies shown in
In this example, each of the support bars 702 can optionally terminate within the support column 102 in a structure 724 that is bent upward. Once again, the structure 724 is designed to extend into the support column 102 and provide additional support and gripping action in an area of maximum stress and load transfer.
The following are example values for various dimensions and other characteristics of the reinforcing assembly 700. The support bars 702 and working members 704 can be formed from #3 rebar. The reinforcing assembly 700 could have a height 732 that is about 1.5 inches shorter than the height of the slab structure 101, allowing for about 0.75 inches on top and bottom of the reinforcing assembly 700. Each of the working members 704 could have upstanding sides 712-714 at an angle 738 of about 6°, and the top portion 708 could have an inner radius of curvature 740 of about one inch. Each of the working members 704 could also have connecting portions 718 with a length 742 of about 1.5 inches, and the working members 704 could be placed at an angle 748 of about 45°±25° on the support bars 702.
The spacings between adjacent working members 704 could be fixed or variable in any suitable manner. For instance, the spacings 750-760 could be about three inches, about 3.5 inches, about 4.25 inches, about 5.25 inches, about 6.5 inches, and about eight inches, respectively. However, any other suitable spacing(s) could be used. Moreover, since the working members 704 lack longitudinal hook structures, a closer spacing could be achieved in the reinforcing assembly 700.
The reinforcing assembly 900 includes multiple support bars 902a-902b (referred to collectively as bars 902) and multiple working members 904 (although a single working member 904 is shown in
In this example, the upstanding sides 912-914 of the working member 904 include two hook portions 910a-910b. The hook portions 910a-910b hook downward in this embodiment, although the hook portions 910a-910b could also hook upward similar to
The following are example values for various dimensions and other characteristics of the reinforcing assembly 900. The support bars 902 and working members 904 can be formed from #3 rebar. The reinforcing assembly 900 could have a height that is about 1.5 inches shorter than the height of the slab structure 101, allowing for about 0.75 inches on top and bottom of the reinforcing assembly 900. The upstanding sides 912-914 could be separated by about four inches, and each connecting portion 918 could be about 1.25 inches in length (with a bottom filet weld of about one inch long). Each of the hook portions 910a-910b could have a radius of curvature of about 0.75 inches and could extend downward about two inches. The working members 904 could be placed at an angle of about 45°±25° on the support bars 902.
In particular embodiments, each working member in the above-described reinforcing assemblies is oriented diagonally, has a knurled or other rough surface (possibly along its full length), and is formed of a small diameter rebar material (such as #3 rebar). This size of rebar could have the highest ratio of surface area-to-cross sectional area (thus increasing its ability to bond most effectively to concrete around it, which can be very useful since the confinement of the slab thickness may severely limit the length of the working members) while being stiff enough to maintain its shape during concrete placement. The use of #3 rebar is not a requirement, however, and other types of materials (such as #4 rebar or #5 rebar) may be used. Moreover, while the reinforcing assemblies are illustrated as having multiple diagonal working members whose spacing from one another varies progressively from an inner to an outer end (relative to the supporting structure), this is not a requirement, either. A reinforcing assembly with at least one diagonal working member having the structural characteristics described and illustrated above is within the scope of this disclosure.
The reinforcing assemblies described above can provide various advantages over conventional approaches (depending on the implementation). The angled (diagonal) orientation of the working members places them at approximately a perpendicular position to potential diagonal-stress punching shear cracks. The ribbed or other roughened surfaces of the working members provide improved or maximum efficiency in engaging concrete at the points of maximum stress, helping to prevent cracks from beginning in the first instance. Because the reinforcing assemblies can inhibit cracks at the points of maximum stress and because the reinforcing assemblies can provide similar reinforcement that crosses the crack zones above and below these points and not far from them, any crack (if it does occur) cannot propagate (extend) upward or downward. If cracking does not occur or if it is held to a very narrow width, the very significant strength of the concrete continues to maintain its integrity and work as a single solid unit as it was designed to do, thereby enabling the supported structure (in which a reinforcing assembly is embedded) to carry maximum shear loads. The rebar and the concrete thus work together, and their respective strengths are additive, rather than (as in the prior art) the concrete failing and transferring all of its load-carrying ability to smooth steel studs (such as in the STUD-RAIL system) or similar reinforcing.
The reinforcement provided by each angled working member develops a bond with the concrete with which it is in contact, thus preventing crack origination and/or propagation. This is because the working member bonds to the concrete on both sides on the crack zone and prevents those concrete segments from moving apart from one another. Thus, the cracking process cannot begin under usual loads. The rebar works with the concrete and supplements it, rather than simply going to work after the concrete has already failed (as in the STUD-RAIL system).
The reinforcing assemblies are easy to manufacture. Each assembly can be made entirely of available materials (such as #3 rebar), and those pieces are readily bent and welded into the assembly using conventional manufacturing techniques (which can be automated).
Although
In this example embodiment, three reinforcing assemblies 1104 are positioned side-by-side at each orthogonal position around the supporting structure 1102. The reinforcing assemblies 1104 could represent any of the reinforcing assemblies described above, and the reinforcing assemblies 1104 may or may not be identical in structure. The reinforcing assemblies 1104 extend outwardly to provide an overall zone of reinforcement around the supporting structure 1102. The reinforcing assemblies 1104 could be between about two feet to about four feet in length, although any other suitable length(s) could be used. Note that one or more additional reinforcing assemblies 1106 could be used in one or both directions for high-stress conditions.
Although
It may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like.
While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.
This application claims priority under 35 U.S.C. §120 as a continuation-in-part of U.S. patent application Ser. No. 12/959,912 filed on Dec. 3, 2010, which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12959912 | Dec 2010 | US |
| Child | 13187311 | US |
