Patent Grant
12203268
The invention relates to materials, components, and construction techniques for reinforcing structural support elements for building structures, such as buildings, bridges, parking garages and towers, using concrete aggregate.
All structures—from huts to skyscrapers and bridges—utilize structural elements to hold them up and keep them from collapsing. Two key structural elements are beams and columns, each playing an essential role in creating a load path to safely transfer the weight and forces acting on a structure to the foundation and into the ground. Beams are horizontal structural elements that withstand vertical loads, shear forces, and bending moments. Beams transfer loads imposed along their horizontal length to endpoints, such as columns, walls, and foundations. Columns are vertical support structures that hold up beams, roofs, and other parts of a building. Generally, a column is a strong, typically cylindrical structure that can extend from floor to ceiling inside a structure, or outside, from the ground up to the first, second or subsequent floors. Each column is designed with the compressive strength to hold the weight of what is above it, which can be very substantial. To construct vertical support structures, conventional construction techniques utilize concrete aggregate in combination with reinforcement materials such as steel rebar.
Concrete aggregate is commonly used in the construction industry. Concrete aggregate includes cement in various combinations with water, sand, gravel, and other materials that help add to its strength in the particular conditions in which the concrete will be employed. For ease of reference, the term “concrete” as used herein includes any of these combinations of cement and other materials that form a concrete aggregate.
Concrete has many advantages, including great compressive strength, good longevity with little maintenance, and it is relatively impervious to weather. However, there are some disadvantages to using concrete to construct columns. One disadvantage is concrete's low tensile strength. For example, if a column were to be made solely of concrete, it would crack and break relatively easily when subjected to tensile axial forces. To compensate for the low tensile strength, an internal structure is commonly utilized. For example, an internal structure may include one or more steel rebar rods situated vertically inside the column to improve the concrete column's tensile strength.
Under normal stress loads and environmental conditions, steel rebar rods as internal structures function adequately with concrete and provide good support for concrete columns. However, under the extreme conditions of fire, corrosion, or earthquakes, the steel reinforcement rods can undermine structural integrity, and destroy the very members they were designed to save. For example, corroding rebar steel, alone, costs every country 3 to 4% of its GDP in maintenance, repair, or replacement. Likewise, when steel rebar is directly exposed to fire, the steel rebar rapidly rises in temperature and can cause loss of the concrete cover due to spalling, which will significantly reduce the load-carrying capacity of the concrete member. When concrete columns are laterally loaded, as in an earthquake, the vertical steel rebar is placed in the precarious position of alternating between being placed under compression, then under tension, and then back again. When under tension, the vertical steel rebar elongates axially, breaking its bond with the concrete and allowing the concrete to crack. As the column bends back on the return swing, the steel rebar is now under compression, with all of the column's gravitational load placed on it. The vertical steel rebar now expands, cracking the concrete even more, spalling the concrete cover, eventually buckling, and forcefully ejecting the concrete core from its reinforcement cage, causing the column to fail, which in turn can bring down an entire building, or at least a portion of it.
Steel rebar has a number of other disadvantages that drive up construction costs. Manufacturing steel rebar requires specialized manufacturing facilities, high heat and expensive processes. Logistical planning is needed to deliver the appropriate amounts and lengths of steel rebar to the jobsite. Planning errors can cause construction delays, which can be costly. Transporting the steel rebar to the construction site can be expensive: steel is heavy and requires appropriate lifting equipment. Once the steel rebar arrives at the jobsite, it must be cut to the appropriate length, which drives up costs. Constructing a concrete structure supported by rebar requires constructing a concrete cover on the support structure to protect the steel rebar from corrosion to some extent, which also drives up costs.
It would be an advantage to provide rebar made of non-corrosive materials. It has been suggested to manufacture rebar with epoxy resin and carbon, glass or basalt fibers. However, manufacturing rebar with resins like epoxy can be very expensive, leading to higher production costs. Furthermore, the mechanical properties of rebar made with epoxy resin are not well-suited to building construction; e.g., rebar made with epoxy resin can lose strength at temperatures as low as 160 degrees Fahrenheit and lose all their tensile strength in a building fire.
It would be an advantage to provide an improved system and method for reinforcing structural support elements for buildings and other structures with non-corrosive building materials. It would also be an advantage to provide rebar at a lower cost, with better resistance against extreme events such fire, and earthquake damage. It would also be an advantage if the construction of the rebar, and support elements such as columns and beams could be produced easier, quicker, and safer.
BMASS rebar is disclosed herein that is useful for reinforcing structural support elements such as columns, beams, foundations or slabs, and more generally to reinforce concrete or masonry support structures in buildings and other structures. BMASS (Braided Multi-Axial Sleeve System) rebar has a substantially solid configuration that includes a concrete core and a flexible, multi-axially braided reinforcement sleeve enclosing the concrete core, which provides sufficiently rigid, yet flexible rebar. The BMASS rebar does not contain polymer resins that would otherwise interfere with flexibility.
The BMASS rebar can be utilized in structural support elements to support a wide variety of structures such as buildings, bridges, and piers. Examples of structural support elements utilizing BMASS rebar are described. One or more BMASS rebars can be embedded in a concrete structure to support and reinforce the structure and thereby provide strong support.
A multi-sleeve embodiment is disclosed in which a BMASS rebar comprises a substantially solid concrete core consisting essentially of concrete with an outer multi-axially braided reinforcement sleeve embedded in the concrete on the perimeter of the core, and an inner reinforcement sleeve embedded in the concrete, situated concentrically within the outer reinforcement sleeve. The outer and inner reinforcement sleeves have a weave that is substantially flexible, and the BMASS rebar does not contain polymer resins that would otherwise interfere with flexibility.
The BMASS rebar can constructed entirely of non-corrosive materials and therefore eliminating the possibility of corrosion that might otherwise undermine the structural integrity of the structure.
The BMASS rebar can be manufactured inexpensively, thus reducing construction costs. Furthermore, the BMASS rebar can be made in many different configurations, which can be designed and/or selected to meet the requirements of a large variety of construction jobs.
A BMASS rebar fabrication method is described that can provide a quick, safe, low-cost, and simpler method to manufacture BMASS rebar on the jobsite, which provides significant advantages in cost, convenience, and avoidance of construction delays.
BMASS rebar offers many advantages over the steel rebar typically used for structural support of concrete structures, and therefore BMASS rebar described herein can replace steel rebar for many uses. Elimination of steel rebar is advantageous for a number of reasons: the properties of steel itself can contribute to the destruction of the structural element during extreme events such as fire, corrosion, or an earthquake. In contrast, the BMASS rebar flexes during these extreme events, allowing the structural element to flex while retaining most of its strength during and after extreme events. The BMASS rebar does not contain polymer resins that would otherwise interfere with sleeve flexibility or could degrade at even moderately high temperatures.
For a more complete understanding of this invention, reference is now made to the following detailed description of the embodiments as illustrated in the accompanying drawing, wherein:
As used herein, the term “concrete”, or “concrete aggregate” includes cement in various combinations with water, sand, gravel, rocks, and other materials that help to add to its strength in the particular conditions in which the concrete will be employed. For ease of reference, the term “concrete” as used herein includes any of these combinations of cement and other materials.
For purposes herein, “concrete” can be defined as including a cement paste, a coarse aggregate, and other materials such as sand. The term “coarse aggregate” includes larger solids, like rock and gravel. The term “cement paste” includes water mixed with cement. When fresh, cement paste typically flows in a semi-liquid manner.
Rebar: Reinforcement Bar. Rebar is an elongated bar (typically a cylindrical rod) used that is used to reinforce a concrete or masonry structure as a tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concrete under tension. Concrete is strong under compression but has low tensile strength. Rebar significantly increases the tensile strength of the structure.
BMASS: Braided Multi-Axial Sleeve System
BMASS rebar element: A BMASS structure that is configured for use as rebar.
A reinforced concrete BMASS rebar is disclosed that has an elongated (typically approximately cylindrical) shape having a first end and a second end, including a substantially solid concrete core consisting essentially of concrete and at least one reinforcement sleeve. The reinforcement sleeve has a substantially flexible, multi-axially braided weave, which provides flexible, yet strong, reinforcement for the BMASS rebar. The multi-axially weaved structure is particularly useful because it defines a type of selective locking mechanism: the weave pattern is close (tight) enough that it contains larger components of the concrete aggregate within the sleeve, yet the weaved pattern and material can allow cement paste to flow into and around the fibers of the sleeve. The flow of cement paste is sufficient to bond the sleeve to the concrete core, while holding the coarse concrete aggregate inside the sleeve.
Furthermore, the flow of cement paste through the gaps expels unwanted air and fills the spaces within the sleeve, so that the sleeve can become almost uniformly filled with concrete. A more uniform fill provides a stronger structure, substantially free of air pockets that might otherwise undermine the BMASS rebar's strength.
Various embodiments of BMASS rebar-reinforced support structures are disclosed herein. Although some of the support structures may be described as a column or a beam; similar principles can be applied to create other support structures such as posts and pilings. Structural implementations using BMASS rebar are disclosed in more detail in this application, and additional advantages are disclosed.
BMASS rebar described herein offers many advantages over the steel rebar typically used for structural support of concrete structures, and therefore the BMASS rebar structure described herein can replace steel rebar in many support structures.
As mentioned in the Background section, steel rebar, which is widely used, has a number of disadvantages that drive up construction costs and limit its functionality when installed. Steel rebar requires specialized manufacturing facilities, high heat and expensive processes. In comparison, manufacturing the BMASS rebar described herein is a much less costly process, and can be done using an extrusion system, for example.
Advantageously, BMASS rebar can manufactured at or near the jobsite, which saves transportation costs and greatly simplifies planning logistics that could otherwise cause construction delays. Furthermore, BMASS rebar can be manufactured to any length specified by the contractor, and to any diameter required by the structural design.
As an additional advantage, BMASS rebar can be implemented in the support structure similarly to how steel rebar is used, so no additional training is required of the workers. Furthermore, due to the absence of steel rebar, no concrete cover would be required on the support structure, therefore no pedestals would be needed in slabs nor concrete covers in beams or columns.
As mentioned in the Background section, installed steel rebar easily corrodes, causing the spalling of concrete and thereby weakening the structure instead of strengthening it. Installed steel rebar readily conducts heat, and in so doing bypasses the concrete cover causing the spalling of concrete during a fire, thereby weakening the structure instead of strengthening it. Advantageously, BMASS rebar does not corrode, therefore the protective concrete cover (e.g., 1-½ inch) is not required on the structural support member in which it is used. Not needing the protective cover, for a given size, more concrete is available for strengthening purposes and therefore the concrete can be utilized more efficiently. Alternatively, the structural support can be made smaller (without the concrete cover that would otherwise be needed to protect steel reinforcement), thereby providing the same strength in a smaller package.
Also, BMASS rebar is made of the same or similar material as the concrete in which it is embedded, has about the same thermal conductivity as that of concrete, which lessens the possibility of any concrete spalling during a fire.
The BMASS rebar 100 can be manufactured in any suitable length; for example, it may be manufactured in standard lengths (e.g. 10, 15, 20 feet) and then cut to the desired length for a particular application on the jobsite, or pieced together if a longer length is needed. Alternatively, it can be manufactured on the jobsite to the specific desired length, which would not require either cutting or piecing together rebar.
In the embodiment of
As will be described, BMASS rebar 100 can be integrated into various structures, in a variety of different configurations, to provide strength and resiliency against damage to the structure it is supporting. Depending upon the application, multiple BMASS elements may integrated into a structure; for example, a concrete column may be reinforced by three or more BMASS elements.
Following is a detailed description of embodiments of reinforcement sleeves that can be used to fabricate BMASS rebar.
BMASS rebar can be fabricated by filling a reinforcement sleeve (such as shown in
A texture may be formed on the outer circumference of the BMASS rebar during or after the pultrusion process, for example a textured pattern may be introduced during pultrusion, or an abrasive element (e.g. sand) may be sprayed on the BMASS rebar at some convenient point in the process. After the concrete has cured, the BMASS rebar can then be cut to length and transported to the construction location. Pultrusion is a continuous process of manufacture with an approximate constant cross-section by pulling the material, as opposed to extrusion which pushes the material.
Instead of fabrication in a manufacturing facility, BMASS rebar can be formed at or near a job site, which advantageously can save costs and time. In one example, portable pultrusion machines can be transported to at or near the jobsite to make the BMASS rebar there using the materials—concrete and the reinforcement sleeves—to fabricate the BMASS rebar to the appropriate configuration and appropriate length, which can greatly save construction costs and time.
In some embodiments, such as the embodiment illustrated in
The particular weave pattern depends upon several factors such as design requirements, the properties of the concrete mixture, and the outside temperature. Different design requirements, and different types of concrete may require a different weave pattern, angle of weave, and type of reinforcement bands/ribbons. In different embodiments the type of concrete can vary, the compression stress of concrete can vary anywhere from less than 3,000 psi to over 10,000 psi, and the water/cement ratio can vary depending on weather conditions, the size of the pour, and the type of cement that is used. All these factors can be considered when selecting the appropriate sleeve for a particular rebar configuration.
In other embodiments, such as will be described with reference to
The material used in the strands can be any material such as metal, plastic, nylon, ceramics, basalt, aramid, carbon fiber, glass fiber, or any natural or synthetic material of suitable strength and durability that has the appropriate characteristics for the desired end application. Carbon, glass and basalt fibers have high melting points and would be especially beneficial where the potential for fire is anticipated.
To choose the appropriate configuration for a particular construction job, one consideration is the strength and flexibility of the sleeve. Generally, a sleeve is selected to have a weave pattern, a strand configuration, and be made of a material that provides appropriate strength for the end use.
Although typically the materials and strand configurations will be consistent throughout the sleeve, in some embodiments some strands may comprise different materials and/or different configurations. For example, in the same sleeve, some strands may be nylon and others may be aramid, some strands may have a wire configuration and others may have a band configuration. The materials and configuration of the strands are chosen based on their properties to create the desired strength, flexibility, and weave pattern of the end product sleeve.
Many different types of strands can be used in the multi-axially braided reinforcement sleeve. Examples of strands include the following:
Generally, the material and configuration of the strands are chosen to be relatively inelastic compared to the sleeve. For example, individual strands made of metal may not bend or stretch easily (i.e., they may be relatively inelastic). However, the overall braided sleeve will be substantially flexible due to its braided pattern, even if the individual strands are inelastic.
Fabricating the multi-axially braided reinforcement sleeve can be accomplished using any suitable method. Many braiding methods are known in the art, and the particular method chosen for forming the braided tubular structure will depend upon the requirements of any particular implementation. A few examples of methods and apparatus that can braid strands to create a tubular configuration are shown in US Patent Publication US20150299916, U.S. Pat. Nos. 7,311,031, 5,257,571, and 5,099,744.
As described above, the configuration of the strands 508, given the material, must be thick enough or of such density to substantially contain the concrete in the weaved pattern. The strands may be relatively inelastic for strength, and the braid pattern provides flexibility to the reinforcement sleeve.
In one embodiment, the braided sleeve has a biaxial weave pattern in which the first set of strands are wrapped around the central axis in a first rotation, and the second set of strands are wrapped around the central axis in a second, opposite rotation. In other embodiments, the braided sleeve may have a triaxial weave pattern, or a combination of an inner sleeve (comprised of a biaxial weave nearly lateral to the length of the column) and an outer sleeve (comprised of a triaxial weave pattern along the length of the column) working together, or other suitable weave patterns.
Many different materials and braid configurations can be implemented. Typically, the braided structure will be formed with a uniform braid pattern throughout its length. Still, many variations are possible with a uniform braid pattern, for example, the weaved pattern could include a finer mesh that would hold in place a stronger but looser weave of a different material. For example, the weaved pattern could include a finer nylon mesh that holds heavier aramid belts that are weaved into sleeves.
In some embodiments, it may be useful to vary the braid pattern in certain areas, so that the braid is nonuniform along its length. For example, one embodiment may create additional strength in certain portions of the sleeve by a tighter weave, or in other embodiments, more flexibility in the braid can be provided by using a looser weave.
The flexibility of the reinforcement sleeve would be adversely affected by the use of resins/polymers on the sleeve as the resins would harden and impair flexibility. The use of resins/polymers on the sleeve should be avoided because of their low melting point, toxin fumes when burnt, and incompatibility with concrete.
The gaps 540 may or may not allow some cement paste to flow through to the outside while holding the concrete inside the sleeve. Advantageously, the flow of some cement paste (and maybe some sand or smaller particles) through the gaps expels unwanted air and fills the spaces within the sleeve, so that the sleeve column becomes approximately uniformly filled with concrete. A more uniform fill provides a stronger column structure substantially free of air pockets that might otherwise undermine the column's strength. The multi-axially weaved structure is particularly useful because it defines a type of selective locking mechanism.
In other embodiments, as shown in
In multi-sleeve embodiments of BMASS rebar, such as will be described with reference to
The inner reinforcement sleeve 1100 may be manufactured in a tubular configuration. In alternative embodiments, the inner reinforcement sleeve 1100 can be formed by wrapping a sheet of unidirectional material so that the direction of the material's strength is substantially lateral to the central axis. The inner reinforcement sleeve 1100 concentrically fits within the outer reinforcement sleeve 1110. In some embodiments, the inner and outer reinforcement sleeves may be connected by any suitable means.
In the embodiment shown in
BMASS rebar can be utilized to strengthen many different structural support elements such as columns, beams, and slabs. Depending upon the implementation, multiple BMASS elements may be integrated into a structural support element. In these support elements, BMASS rebar is typically internally situated longitudinally along the axis of the support element; e.g., BMASS rebar may be situated longitudinally in a column; however, the BMASS rebar may be situated in any orientation that provides the needed support.
It should be apparent that BMASS rebar can be integrated into various structural support elements, in a variety of different configurations, to provide strength, and resiliency against damage. Following are examples of structural support elements reinforced with BMASS rebar.
In the embodiment illustrated in
As shown in
As discussed above, BMASS rebar can be utilized to strengthen many different structural support elements, such as columns, beams, pilings, and posts. These structural support elements maybe be used to support many different structures. Following are examples of structures that can utilize support elements reinforced with BMASS rebar, it should be apparent that many different structures can use BMASS-reinforced rebar.
This simple support structure 2000 may be a utilized to support a wide variety of structures, for example, either side of a bridge and columns in a structure. The columns 2021,2022 may be formed with a notch or other cut-out shaped to receive the respective ends of the BMASS-reinforced beam 2010. A load 2030, which may, for example, be a bridge, road surface, or the floor of a building, exerts downward forces all along the adjacent surface of the BMASS element, as illustrated by arrows. Generally, the columns must be strong enough to hold against the forces exerted by the load on the structure 2000.
The pilings support a platform 2105, which, for example may be the walkway of a dock, or a road for autos. The pilings 2110, 2120 are set deeply into the sea floor 2130, under the water 2140 in order to stabilize the structure 2100.
Advantageously, the concrete and sleeve material used to manufacture the BMASS rebar 2112, 2122 could be customized to meet different conditions such as the environmental demands of the sea floor, or structural requirements. For example, in a water (or humid) environment, the BMASS rebar would not rust, unlike steel rebar.
BMASS rebar could be utilized to reinforce BMASS posts, which could be manufactured in custom diameters, for example two, three or four inches. Customization could be done on the jobsite.
Each post is made of concrete or other suitable material and is reinforced with BMASS rebar. Particularly, the first post 2210 is reinforced by a first BMASS rebar 2011, the second post 2220 is reinforced with a second BMASS rebar 2221, and the third post 2230 is reinforced with a third BMASS rebar 2231.
Alternatively, larger diameter BMASS rebar itself could be used as micro/mini piles, small support columns or just simple fence posts. For example, 2-, 3-, or 4-inch BMASS rebar could be manufactured, cut into suitable lengths, and used as piles, support columns or fence posts.
Advantageously, the concrete and sleeve material used to manufacture the BMASS rebar and posts could be customized to meet different conditions such as the environmental demands of the soil, or structural requirements.
Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open-ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like; the term “example” is used to provide examples of instances of the item in a discussion, not an exhaustive or limiting list thereof, the terms “a” or “an” should be read as meaning “at least one,” “one or more” or the like; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future.
A group of items linked with the conjunction “and” should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as “and/or” unless expressly stated otherwise. Similarly, a group of items linked with the conjunction “or” should not be read as requiring mutual exclusivity among that group, but rather should also be read as “and/or” unless expressly stated otherwise. Furthermore, although items, elements, or components of the disclosed method and apparatus may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated.
The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent. The use of the term “module” does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all of the various components of a module, whether control logic or other components, can be combined in a single package or separately maintained and can further be distributed in multiple groupings or packages or across multiple locations.
Additionally, the various embodiments set forth herein are described with the aid of block diagrams, flow charts, and other illustrations. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives can be implemented without confinement to the illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular architecture or configuration.
Reference is made, and priority is hereby claimed to co-pending U.S. patent application Ser. No. 17/943,067 filed Sep. 12, 2022 entitled CABLE-SUPPORTED STRUCTURAL ASSEMBLY WITH FLEXIBLE REINFORCED CONCRETE STRUCTURAL ELEMENT, U.S. patent application Ser. No. 17/836,226, filed Jun. 9, 2022, now U.S. patent Ser. No. 11/619,047, entitled BRAIDED MULTI-AXIAL SLEEVE SYSTEM USED AS A STRUCTURAL REINFORCEMENT FOR CONCRETE COLUMNS AND METHOD FOR CONSTRUCTING CONCRETE COLUMNS, U.S. patent application Ser. No. 16/996,905, filed Aug. 19, 2020, now U.S. Pat. No. 11,408,176 entitled MULTI-AXIALLY BRAIDED REINFORCEMENT SLEEVE FOR CONCRETE COLUMNS AND METHOD FOR CONSTRUCTING CONCRETE COLUMNS, and U.S. Provisional Patent Application No. 62/888,854, filed Aug. 19, 2019, entitled MULTI-AXIALLY BRAIDED REINFORCEMENT SLEEVE FOR CONCRETE COLUMNS AND METHOD FOR CONSTRUCTING CONCRETE COLUMNS, all of which are incorporated herein by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
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| 6123485 | Mirmiran | Sep 2000 | A |
| 6295782 | Fyfe | Oct 2001 | B1 |
| 20150190972 | Ehsani | Jul 2015 | A1 |
| 20190177992 | Saadatmanesh | Jun 2019 | A1 |
| 20200284055 | Saadatmanesh | Sep 2020 | A1 |
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| 2022056410 | Mar 2022 | WO |
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