US20180328039A1 - Systems, apparatuses, and methods related to fiber strands used in reinforced concrete - Google Patents
Systems, apparatuses, and methods related to fiber strands used in reinforced concrete Download PDFInfo
- Publication number
- US20180328039A1 US20180328039A1 US15/979,256 US201815979256A US2018328039A1 US 20180328039 A1 US20180328039 A1 US 20180328039A1 US 201815979256 A US201815979256 A US 201815979256A US 2018328039 A1 US2018328039 A1 US 2018328039A1
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- strands
- carbon fibers
- reinforcing bar
- set forth
- resin
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- Abandoned
Links
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- 239000000835 fiber Substances 0.000 title claims description 25
- 239000011150 reinforced concrete Substances 0.000 title 1
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 101
- 229920000049 Carbon (fiber) Polymers 0.000 claims abstract description 77
- 239000004917 carbon fiber Substances 0.000 claims abstract description 77
- 239000011347 resin Substances 0.000 claims abstract description 40
- 229920005989 resin Polymers 0.000 claims abstract description 40
- 239000004567 concrete Substances 0.000 claims description 61
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 32
- 238000007598 dipping method Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 description 34
- 239000011178 precast concrete Substances 0.000 description 22
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- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 238000004873 anchoring Methods 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
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Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
- B28B23/02—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members
- B28B23/04—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members the elements being stressed
- B28B23/043—Wire anchoring or tensioning means for the reinforcements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/06—Fibrous reinforcements only
- B29C70/10—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres
- B29C70/16—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/54—Component parts, details or accessories; Auxiliary operations, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing
- B29C70/56—Tensioning reinforcements before or during shaping
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01H—SPINNING OR TWISTING
- D01H7/00—Spinning or twisting arrangements
- D01H7/02—Spinning or twisting arrangements for imparting permanent twist
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
- D06M11/84—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising combined with mechanical treatment
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/38—Connections for building structures in general
- E04B1/41—Connecting devices specially adapted for embedding in concrete or masonry
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/38—Connections for building structures in general
- E04B1/41—Connecting devices specially adapted for embedding in concrete or masonry
- E04B1/4171—Nailable or non-threaded screwable elements
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
- E04C5/07—Reinforcing elements of material other than metal, e.g. of glass, of plastics, or not exclusively made of metal
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
- E04C5/08—Members specially adapted to be used in prestressed constructions
- E04C5/085—Tensile members made of fiber reinforced plastics
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
- E04C5/08—Members specially adapted to be used in prestressed constructions
- E04C5/12—Anchoring devices
- E04C5/127—The tensile members being made of fiber reinforced plastics
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C2791/00—Shaping characteristics in general
- B29C2791/003—Making articles of indefinite length
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/40—Shaping or impregnating by compression not applied
- B29C70/50—Shaping or impregnating by compression not applied for producing articles of indefinite length, e.g. prepregs, sheet moulding compounds [SMC] or cross moulding compounds [XMC]
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
- D06M2101/40—Fibres of carbon
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C3/00—Structural elongated elements designed for load-supporting
- E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
- E04C3/20—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of concrete or other stone-like material, e.g. with reinforcements or tensioning members
- E04C3/26—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of concrete or other stone-like material, e.g. with reinforcements or tensioning members prestressed
Definitions
- the present invention is related to resin impregnated carbon fiber, and more particularly, to systems, methods and apparatus related to the use and formation of a resin impregnated carbon fiber.
- Concrete is used in many different types of construction projects, including, but not limited to walls, retaining walls, bridges, roadways, building foundations, etc. . . . .
- Concrete is a composite material that is composed of coarse aggregate bonded together with a fluid cement that hardens over time. Concrete may be poured off-site in forms to obtain a concrete structure in a desired shape and then transported on-site to be installed or it may be poured on-site in field constructed forms.
- reinforcing members are composed of corrosion susceptible steel, such as reinforcing bar or rebar.
- steel will degrade into iron oxide commonly referred to as rust. This degradation will eventually diminish the integrity of the rebar, and thus, the concrete structure.
- steel rebar may have a deformity, i.e., a deformed pattern that is designed to increase the friction between rebar and the material in which it is embedded.
- carbon fiber based rebar is comprised of a plurality of unidirectional glass fibers that have been reinforced or thermoset with resin.
- the widely accepted properties of carbon fiber strands indicate that a member with a small cross-section will perform quite well in tension, but very poorly in shear. This is a fact that was experimentally confirmed during testing of a carbon fiber rebar (CF) with parallel carbon fiber strands. It was also found that a CF sample wherein all fibers are parallel with no surface deformations does not have sufficient bond strength with a cementitious material. This fact has since been confirmed by the American Concrete Institute (ACI) (440.6-3). The ACI goes as far as to require suppliers of fiber reinforced polymer (FRP) to provide the method by which the surface of the FRP is deformed.
- FRP fiber reinforced polymer
- the deformed pattern may be replicated by “pinching” of the fibers prior to being set by the resin. However, this does not overcome the deficiencies of carbon fiber based rebar over steel rebar.
- the present invention is aimed at one or more of the problems set forth above.
- a reinforcing bar in a first aspect of the present invention, includes a plurality of strands and a deformity pattern.
- Each strand includes a plurality of carbon fibers.
- the strands having been impregnated with a resin and twisted forming a unified structure.
- the deformity pattern being formed within the unified structure by twisting the strands a predetermined number of times per linear foot of the unified structure and allowing the resin-impregnated unified structure to cure.
- a concrete structure in a second aspect of the present invention, includes a concrete member and a reinforcing bar.
- the concrete member is formed about the reinforcing bar while the reinforcing bar is under stress.
- the reinforcing bar includes a plurality of strands. Each strand includes a plurality of carbon fibers.
- the strands have been impregnated with a resin and twisted forming a unified structure.
- a deformity pattern within the unified structure is formed by twisting the strands a predetermined number of times per linear foot of the unified structure and allowing the resin-impregnated unified structure to cure.
- a method in a third aspect of the present invention, includes the steps of dipping a plurality of strands of carbon fibers in a bath of resin, pulling the strands of carbon fibers through an outgoing pair of rollers, as the strands leave the bath of resin, and twisting the strands of carbon fibers together to form a desired deformity pattern.
- the method further including the steps of allowing the resin to cure to form a reinforcing bar.
- FIGS. 1A and 1B are explanatory diagrams of parameters associated with an exemplary reinforcing rod associated with the present invention
- FIGS. 1C through 24C are diagrammatic illustrations of a reinforcing bar, rod or member and/or structures used in the production of a reinforcing bar, rod or member, according to embodiments of the present invention
- FIGS. 25-31 are diagrammatic illustrations of systems for allowing (building) components to attach to a concrete member, according to embodiments of the present invention.
- the present invention is related to reinforcing bars and/or concrete structures with reinforcing bars.
- the reinforcing bars may be resin impregnated carbon fibers.
- the present invention may be related to systems, methods and apparatus, related to the formation and use of resin impregnated carbon fibers and/or methods and structures to apply tension or stress to reinforcing bars and/or methods or structures related to the production of concrete structures.
- a reinforcing bar composed of carbon fiber strands is provided.
- a system and method for producing reinforcing bar composed of carbon fiber strands is provided.
- an apparatus for producing reinforcing bar composed of carbon fiber strands is provided. It should be noted that the terms reinforcing bars, reinforcing rods and reinforcing members may be utilized interchangeably.
- the carbon fiber based reinforcing bar may be composed from a plurality of carbon fibers which are wound or twisted and then set in a resin. For example, in one embodiment, three strands of approximately 50,000 carbon fibers each are twisted together and then set (or thermoset) in a resin. The twist forms the deformations or deformation pattern that provides the friction between the rebar and the material in which the rebar is set. In one embodiment, the number of twists per a given length of the carbon fibers is predetermined and determined as a function of the number and size of fibers and/or strands of fibers.
- each strand of carbon fibers may be composed from a tow of carbon fiber filaments.
- Each tow of carbon fiber filaments has an approximate predetermined number of carbon fiber filaments. Typical, tows may have 20,000; 30,000; 40,000, 50,000 or other approximate number of filaments.
- the critical parameter is the overall strength of the resulting reinforcing bar, rod or member.
- the size of each filament and the number of filaments in different tows may differ. Therefore, based on the size of the filaments, the (approximate) number of filaments in each tow and the desired strength of the resulting member, rod or bar, the number of strands may be determined.
- a single tow may be used. In these embodiments, the single tow may be considered as including two or more strands. The two or more strands in the single two are twisted to create the non-uniform surface (see below).
- FIG. 1A illustrates the transfer of tensile load into shear load. This can be described as Measured Load*(sin(A)). It should also be noted that the tension in the fibers at this location is described as Measured Load*(COS(A)).
- the carbon fiber based reinforcing bar is formed by pulling carbon fibers (under tension) through a resin bath and simultaneously, or shortly thereafter, twisting the fibers.
- the resin impregnated twisted carbon fibers are then left under tension while the resin cures.
- the apparatus 10 includes a bath housing 12 (which is shown in cross-section in FIGS. 1C and 1D ).
- the bath housing 12 forms a reservoir 14 .
- the reservoir 14 is filled with (uncured) resin.
- the apparatus 10 includes at least one incoming roller 16 , a series of bottom rollers 18 and a pair of outgoing rollers 20 .
- aligned carbon fibers enter the apparatus 10 (from the left in FIG. 1C ) and are directed over the incoming roller 16 .
- the fibers are then directed towards (into the resin bath) and around the bottom rollers 18 .
- the fibers are pulled through the outgoing rollers 20 .
- the carbon fibers are in the form of a strand of a plurality of carbon fibers. In a specific embodiment, three strands of 50,000 carbon fibers each are used.
- the three strands are pulled (or pultruded) through the resin bath simultaneously and after the fibers leave the resin bath, are twisted together. A more specific system and method is described below.
- the (dry) carbon fiber is pultruded through a series of rollers 16 , 18 , 20 under a constant tension in a resin bath in order to ensure complete impregnation of the resin through all fiber strands.
- the fibers are saturated with resin, they are pultruded through a single slot 22 (which may be located in a block mounted adjacent the bath housing 12 ) to remove excess resin (see FIG. 1E ).
- This step also ensures all of the fibers are aligned and that the cross-sectional area of the strand is within the acceptable range for the given (or intended) application.
- This step also ensures that the ratio of CF to epoxy is appropriate.
- the fibers are then left under a tension load which keeps all fibers aligned during curing.
- the block shown in FIG. 1D
- the block will include a slot for each strand of fibers.
- the predetermined number of twists is determined as a function of the number and size of the carbon fibers and/or number and size of the strands of carbon fibers. In another aspect of the present invention, the predetermined number of twists may be determined as functions of the shear load required of the reinforcing rod, bar or member.
- the strand is allowed to cure per resin manufacturer's suggestion, at which time it is ready to be used in production. Again, it is important to note that the strand remains under load during the curing process and that the twists are applied to the strand before the curing process begins.
- the rebar After the resin impregnated carbon fiber based rebar has been cured, the rebar is ready to be used.
- the carbon fiber based rebar may be brought under tension and a cement structure is formed around the pre-stressed fiber based rebar. Once the concrete has cured, the tension force from the rebar may be released.
- a system 50 for pre-stressing a reinforcing member within a pre-cast structure is shown.
- the system 50 is particularly useful in pre-stressing a fiber base reinforcing member, such as a carbon fiber based rebar.
- a carbon fiber based rebar as detailed above with respect to FIGS. 1A-1D may be used.
- the system 50 may be used with any fiber based reinforcing bar.
- the system 50 includes three main components: a gripping device 52 , a tension device 54 and a tension application sub-system 56 (A & B).
- the gripping device 52 is used to provide an attachment to each end of a reinforcing member (or rebar) 58 .
- the gripping device 52 includes a gripping tube 60 , such as a steel tube 60 .
- the gripping tube 60 has a calculated length, outer diameter and inner diameter. The parameters of the gripping tube 60 are determined to provide enough friction force between the gripping tube 60 and the reinforcing member 58 given the tension force that needs to be applied while the pre-cast structure is being cast (see below).
- the gripping tube 60 is then filled with an expansive grout 57 .
- a cap 62 (see FIGS. 13 and 14 ) with a pre-drilled hole in the center to guide the reinforcing member 58 is then placed on the gripping tube 60 .
- Cap 62 is multi-functional in that it contains the expansive grout 57 as well as ensures that reinforcing member 58 is concentric with gripping tube 60 .
- the reinforcing member 58 is then inserted through the cap 62 and into the grout 57 .
- the expansive grout 57 creates a bond on both the reinforcing member 58 and the inside of the gripping tube 60 .
- This bond becomes a friction force upon the application of tension to the gripping tube 60 (one on each end of the reinforcing member 58 ) by the system 50 .
- the friction force is a function of the gripping tube 60 , e.g., the length and diameter(s) of the gripping tube 60 , as well as the grout 57 .
- the gripping tube 60 is designed such that the friction force has a an ultimate strength greater than the tension force applied to the structure allowing the gripping tube 60 to be used as an attachment point for the tensioning process. It is important to note that the outer diameter of the grout tube is also limited by the designed distance between the reinforcing members 58 . The outer diameter of the tubes 60 must be smaller than the centerline distance between the reinforcing strands to ensure that the tubes 60 for each member 58 do not inhibit one another. The same principal applies to the next part in the tension system 50 , as well.
- the tension device 54 includes a tension tube 64 , allows the tension application sub-system 56 to quickly and easily be attached to the gripping device 52 .
- the tension tube 64 which may also be made of steel, has a specified length, outer and inner diameter such that the gripping tube 60 fits inside.
- the size of the tension tube 64 is determined such that the outer diameter of the gripping tube 60 is smaller than the inner diameter of the tension tube 64 .
- the outer diameter of the tension tube 64 is also limited by the designed distance between the reinforcing members 58 (see above). That is, the outer diameter must be smaller than the centerline distance between the reinforcing members 58 to ensure that the gripping tubes 60 and tension tubes 64 for each strand do not inhibit one another. If this dimension were to become a limiting factor in the design of the reinforcing element location another tension application system would have to be designed to accommodate.
- an insert slot 66 is machined out of the top of the tension tube 64 .
- the insert slot 66 allows the gripping tube 60 to be inserted quickly without compromising strength and reducing the amount of time necessary to remove the tension tub and reinstall the next new tension tube for reinforcement bar tensioning.
- a smaller slot 68 allows the member 58 to also be inserted into the tension tube 64 .
- One end of the tension tube 64 is (at least partially) closed (see FIG. 9 ) and includes the smaller slot 68 that allows the reinforcing strand to extend there-through when the grout tube is inserted into the tension tube.
- tension tube 64 may be threaded (not shown) to allow the attachment of a threaded rod (see below) which connects tension device 54 to be connected to the tension application sub-system 56 .
- a tension tube 64 may be used at both ends of each reinforcing member 58 such that tension can be adjusted at either end.
- the tension application sub-system 56 includes a first tension application apparatus 56 A and a second tension application apparatus 56 B, one at each end of the members 58 . While only one tension application apparatus 56 A, 56 B is shown, the other apparatus 56 A, 56 B is identical. As will be explained in more detail below, the tension within the members 58 may be adjusted at either end through the respective tension application apparatus 56 A, 56 B. It should be noted that in the top down diagrams of FIGS. 2A and 2B , two members 58 are shown. However, in the illustrated embodiment, four members 58 are used.
- each tension application apparatus 56 A, 56 B includes first and second assembly brackets 70 A, 70 B.
- the first and second removable brackets 70 A, 70 B each include a base 70 with a plurality of through holes 76 .
- the tension application apparatus 56 A, 56 B may be mounted, e.g., bolted, to a surface (see for example, FIGS. 24A, 24B and 24C ) via the through holes 76 .
- the first and second assembly brackets 70 A, 70 B may be fixed together using bolts (not shown) through alignment holes 74 in respective upright corner walls 72 A- 1 , 72 A- 2 , 72 B- 1 , 72 B- 2 .
- An interchangeable, removable plate 78 is provided between the first and second assembly brackets 70 A, 70 B.
- a coupling mechanism 80 For each gripping device 52 /tension device 54 pair, a coupling mechanism 80 is provided.
- the coupling mechanism 80 couples the respective gripping device 52 /tension device 54 pair to the tension application apparatus 56 A, 56 B.
- the coupling mechanism 80 includes a first threaded rod 82 .
- a first end of the first threaded rod 82 is threaded into a threaded aperture in the opposite end of the tension tube 64 of the tension device 54 (or otherwise coupled thereto).
- the opposite end of the first threaded rod 82 is threaded into one end of a respective load cell 84 (or otherwise coupled thereto).
- a second threaded rod 86 is threaded into a second end of the respective load cell 84 .
- the opposite end of the second threaded rod 86 is inserted through a respective hole in the plate 78 .
- An adjustment nut 88 is threaded onto the opposite end of the second threaded rod 86 . Rotation of the adjustment nut 88 controls the tension or force applied to the respective member 58 .
- the tension imposed on the members 58 causes a deflection (in either direction) within the respective load cell 84 which may be measured.
- the assembly brackets 70 A, 70 B hold the plate 78 in place and are securely fastened to a true and secure surface with adequate structural capacities.
- the assembly brackets 70 A, 70 B are coplanar to ensure that the reinforcing members 58 under tension are level.
- An integral portion of the bulk head is the plate through which the threaded rods are inserted and the adjustment nut(s) 88 tightened against. The bulk head is designed such that this plate 78 is removable for quick and easy alteration of the reinforcing strand locations.
- the pre-cast structure is formed using a form shape or mold 90 .
- the members 58 extend from the first tension application apparatus 56 A, through the form 90 , to the second tension application apparatus 56 B.
- the first step is to place all reinforcing members 58 required for the pre-cast structure into the form 90 with the gripping tubes 60 in the respective tension tubes 64 .
- Tension is then applied to the system via the adjustment nuts 88 and set to the proper torque to yield the correct value in tension.
- the cementitious material may be then poured into the form 90 , around the reinforcing members 58 .
- Tension is again verified before the cementitious material is left to cure. After the material is cured to the proper strength, the tension is systematically released at an equal rate among all reinforcing members 58 .
- the gripping tubes 60 may be cut off (and disposed of) and the member is removed from the form 90 .
- the forms 90 can be cleaned and the system 50 prepared to begin the process over again.
- the dimensions chosen for the prototype concrete member were governed by the dimensional, and load bearing requirements of the chosen construction system, the ACI cover depth requirements for reinforcing members 58 , and load capacity of reinforcing members 58 .
- the ACI requires a minimum cover depth based on reinforcing member material and corrosive properties. That is to say there is a minimum distance from the surface of the concrete member to the closest surface of the reinforcing element. It is important to note that the cover depth for a composite fiber reinforcing element is less than that of a steel reinforcing element due to the difference in corrosive properties. This requirement shows that a member reinforced with a composite element could have a thinner cross sectional area than one reinforced with steel.
- the minimum cover depth for a steel member is 0.75′′, therefore a member with a single 0.25′′ reinforcing element could only be 1.75′′ thick at the minimum. Whereas a composite member requires 0.375′′ of cover therefore the same size reinforcing element could yield a member 1′′ thick. It was this principal along with the engineered load rating for the member that would govern the dimensions chosen for the prototype composite reinforced, precast, pre-stressed concrete member.
- a different type of material e.g., wood
- different building parts must be attached to the precast concrete structure.
- this method should increase versatility and facilitate quicker installation of fastener parts for optimal onsite field construction efficiency.
- a first attachment part 91 A and a second attachment part 91 B may be embedded in a pre-stressed, pre-cast structure.
- the first attachment part 91 A has a first body 93 A.
- the first body 93 A has a first concrete structure facing side 95 A and a first plurality of attachment members 97 A extending from the concrete structure facing side 95 A.
- the second attachment part 91 B has a second body 93 B.
- the second body 93 B has a second concrete structure facing side 95 B and a second plurality of attachment members 97 B extending from the concrete structure facing side 95 B (see below).
- the first and second attachment parts 91 A, 91 B may be spaced apart forming a compressible junction 99 therebetween.
- the pre-cast, pre-stressed concrete structure is formed from uncured cement. At least of a portion of the first and second attachment members 97 A 97 B are embedded in the pre-cast, pre-stressed concrete structure.
- the first and second attachment parts 91 A, 91 B may be composed of wood, lumber, plastic, metal or a composite material.
- a system 100 includes one or more attachment parts or blocks, e.g., pieces of wood or lumber, being integrated with the precast cement structure.
- Concrete is a material that requires pre-drilling, so it may require additional work to attach pieces, building components to the cement structure.
- the use of an attachment part or block allows for the easy and efficient installation of building components, for example, ribbed steel panels. The panels may be bolted or otherwise fastened to the integrated piece of lumber.
- an exemplary block, e.g., piece of lumber, 102 is shown that may be integrated with the precast cement structure during the casting process (see above).
- the block 102 includes a number of shear studs 104 embedded therein.
- an even number of shear studs 104 are provided: one half of the shear studs 104 on one side of the center of the block 102 and one half of the shear studs 104 on the other side of the center of the block 102 .
- an odd number of shear studs 104 may be provided.
- the shear studs 104 may be cast into the concrete member during the pouring process. As discussed above, the applied tension on the rebar is released after the cement is cured. When the tension is released in the cured, pre-tensioned, precast concrete structure, a compression force (see FIG. 25 ) is transferred causing the structure to decrease in length in an incremental amount varying by the tension applied, the cross-sectional area of the member, and its composition.
- this issue may be solved by creating a relief cut in the block 102 or provide a plurality of blocks 102 with a relief or space.
- the relief may be filled with a compressible material 108 casting the pre-cast concrete structure 106 .
- This “compressible void” acts as a cushion for the blocks 102 to compress along with the precast concrete structure 106 .
- a method is provided. Stress is applied to a reinforcing member.
- the first and second attachment parts are positioned at predetermined positions relative to the reinforcing member.
- the first attachment part has a first body.
- the first body has a first concrete structure facing side and a first plurality of attachment members extending from the concrete structure facing side.
- the second attachment part has a second body.
- the second body has a second concrete structure facing side and a second plurality of attachment members extending from the concrete structure facing side.
- the first and second attachment parts are spaced apart forming a compressible junction.
- a concrete form is positioned at a predetermined location about the reinforcing member and the first and second plurality of attachment members.
- Uncured cement is poured in the concrete form. The uncured cement encases at least partially, the reinforcing member and the first and second plurality of attachment members. Then, the cement is allowed to cure and the stress is released from the reinforcing member.
- the steps of this method do not necessarily need to be performed in the order listed above.
- the step of positioning the first and attachment parts at predetermined positions relative to the reinforcing member may be performed before or after the uncured cement is poured into the form.
- a method to attach the block or lumber 102 to the precast concrete structure 106 is provided.
- a system 100 of mechanical anchoring is required.
- a series of shear studs 104 is placed in the lumber or block 102 . A portion of the length of each shear stud 104 remains exposed.
- the cementitious material is then cast around the shear studs 104 , thereby bonding the lumber to the precast concrete structure 106 .
- the spacing of the shear studs 104 is critical and varies depending on the amount of load that is required to be transferred from the block(s) 102 into the precast concrete structure 106 .
- the frequency of the shear studs 104 may be increased beyond the minimum requirement to allow the cement structure(s) to be cut in any location while maintaining adequate shear transfer.
- FIGS. 26A-27C The method of applying shear studs 104 to the underside of a block or wooden member 102 before the member is cast in cementitious material is shown in FIGS. 26A-27C .
- the spacing between studs is 4′′ though this is subject to change with corresponding structural loads to be transferred into the precast concrete structure 106 .
- the size of the lumber block 102 depicted is a 1.5′′ cross sectional-square though this is also subject to change dependent on the application.
- FIGS. 26A-26C illustrate a block 102 having a square cross-section.
- the block 102 is composed of a 1.5′′-1.5′ treated lumber block 102 having a maximum length of 24′′.
- the shear studs 104 are corrosive resistant fasteners having a 4′′ spacing.
- the block 102 has a groove (as shown) that may be useful for fastening building components thereto.
- the first and second attachment parts may be made from metal.
- an integral piece of galvanized steel or metal plate 200 may include with the concrete structure to facilitate an easy installation of building components.
- casting a section of galvanized steel 200 ( FIG. 30A ) into a pretensioned concrete structure poses new problems that must be addressed in order maintain a structurally sound member.
- a system 200 includes one or more metal plates 204 that are integrated with the precast, pre-stressed concrete structure 210 . This allows for the easy and efficient installation of building components, for example, ribbed steel panels.
- the system 200 includes a plurality of plates 204 .
- each plate 204 includes an upright member 205 to which building components may be fastened.
- Each plate 204 also includes a slot and groove mechanism 206 that provides a slip joint between adjacent plates 204 .
- the slot and groove mechanism 206 includes a tab 206 B and a plurality of offset horizontal members 206 A which are offset to form a slot for receiving a tab 206 B from an adjacent plate 204 .
- Each plate 204 also includes a plurality of fins 208 .
- the fins 208 are embedded in the uncured cement that forms the precast, pre-stressed cement structure 210 .
- each fin 208 has a hole.
- the concrete structure 210 When the tension is released in the cured, pretensioned, precast concrete structure 210 , the concrete structure 210 will decrease in length in an incremental amount varying by the tension applied and the cross-sectional area of the structure 210 . This poses a problem for any material that is cast into the pretensioned, precast concrete structure 210 as the item cast into the item must have the ability to be slightly compressed. If the item cast into the precast concrete structure 210 , and the member is not compressible at a rate similar to the concrete structure 210 then the resulting internal stresses can cause unacceptable deflection of the entire member.
- the first method involves creating a slip joint between sections of metal plates 200 . This allows smaller pieces of galvanized metal to be used and allows them to “slip” a small amount at the joints where the two pieces meet.
- the second method for solving this issue involves leaving a gap between the pieces of galvanized metal fin and filling said gap with a compressible material. This “compressible void” allows the metal plates 200 to move closer together (or further apart) as tension is released thus relieving a portion of the internal stress in the material yielding a finished product that is suitable for the intended use.
- This relationship along with the determination of an acceptable deflection range may be used to find the optimal length of the plate 200 as well as optimal dimensions for the “compressible voids” or “slip joints.” This same relationship could also be used to show that a higher pre-tensioning load would require a decrease in the length of plate 200 in order to keep deflection within said acceptable range.
- the second problem comes with developing a method to attach the galvanized steel or “plate 200 ” to the precast member. While the galvanized steel will chemically bond to the cementitious material to a certain extent, a level of mechanical bonding is required. This is often achieved by creating a surface on the material that is non-uniform. A non-uniform surface will create small shear faces in the cementitious material along the length of the bonding surface. In the case of the galvanized steel fin 208 A, 208 B, this can be achieved by altering the surface geometry of the part. Both putting holes in the fins 208 A, 208 B and putting bends in the part will each sufficiently increase the bond strength of the galvanized steel and the concrete to a level that is acceptable for this application.
- fins 208 or plate 200 is made from a corrosive resistant material or may be coated with a corrosive resistant substance or protection layer.
- a steel sample is cast within a concrete member there is the potential that the steel will deteriorate over time causing the concrete sample to crack, spall and eventually fail. This is caused in part by chloride ions within the concrete sample that break down the protective layer around the steel that is created during the early stages in the concrete curing process. Once this protective layer is gone, there is opening for oxidation of the iron ions within the steel which yields iron oxide or what we refer to as rust.
- the process of galvanization adds a protective layer of zinc over the entire steel part. Once within the concrete this protective zinc coating propagates out, creating an even broader barrier against the chloride ions and oxidation.
- a method of producing a galvanized metal plate 200 that can be cast into a pretensioned, precast concrete member and that facilitates the attachment of said structure to other building components is provided.
- the galvanized plate 200 is of an altered cross sectional geometry such that the shape adds an increased level of mechanical bonding with the cementitious material it is cast into.
- the galvanized plate 200 is of a specified length which is varied in relation to the application and pretensioning loads used in given member. The relationship is such that a higher pretension load will require a shorter maximum length plate 200 .
- the ends of each plate 200 are shaped in such a manner that they fit together as a “slot and tab” mechanism. This allows the plate 200 and cementitious member 210 to move linearly with respect to one another without moving in the shear direction.
- a method of attachment for all building parts must be developed. This method should increase versatility and facilitate quicker installation of fastener parts for optimal connection efficiency. It was determined that an integral nailable substrate could be included with the concrete member to facilitate an easy installation of, e.g., steel panels or exterior sheathing along with the corresponding trims and accessories. Casting a section of a nailable material with attachment members 97 A, 97 B (see above), such as shear studs, into a pre-tensioned concrete member poses new problems that must be addressed in order to maintain a geometrically sound and acceptable member.
- the relationship between tension force, modulus of elasticity and overall length change of the member is such that a higher force with and equal Young's Modulus will yield a larger decrease in length. Furthermore, if the tension force is equal and the modulus of one portion of the member is lower than another portion of the member, the section with a lower modulus will decrease in length by a greater amount. If we combine these two ideas it could be stated that if a member has a large variance in Young's Modulus, the tension force could be varied through the plurality of reinforcing elements such that the overall decrease in length of the member would be consistent throughout.
- a method to attach the nailable substrate to the precast concrete is provided.
- a system of mechanical anchoring is required. It was found that a series of attachment members, e.g., shear studs, could be placed (attached, screwed, nailed, driven, etc. . . . ) in the nailable substrate with a portion of the length of said stud remaining exposed. The cementitious material is then cast around these studs bonding the nailable member to the cast concrete member.
- the spacing of these studs is critical and varies depending on the amount of load that is required to be transferred from the nailable substrate into the precast concrete member. Frequency of studs is increased beyond the minimum requirement to allow members to be cut in any location while maintaining adequate shear transfer.
- FIG. 31 The method of applying studs to a face perpendicular to the intended nailing face of a nailable member before said member is cast in cementitious material is illustrated in FIG. 31 .
- the spacing between studs in this figure is 4′′ though this is subject to change with corresponding structural loads to be transferred into the concrete member.
- the size of the nailable member is a standard nominal “2 ⁇ 4” though this is also subject to change dependent on the application.
- the studs in the nailable member should be placed such that they do not interfere with any reinforcing elements that may be within the cementitious material. It is also important to note that the shape of the nailable member is not restricted. Any shape that suits a particular application as long as there is a flat base for the installation of the studs will be acceptable.
- the shear studs used should be comprised of a corrosion resistant material.
- reinforcing elements may be suitable reinforcing member, bar, rod, including the reinforcing members, bars, or rods disclosed herein, or any other suitable reinforcing member.
Abstract
Description
- This application claims priority to U.S. Provisional Patent Application Ser. No. 62/506,432, filed on May 15, 2017 and U.S. Provisional Patent Application Ser. No. 62/571,920, filed on Oct. 13, 2017, the disclosures of which are hereby incorporated by reference in their entirety and for all purposes.
- The present invention is related to resin impregnated carbon fiber, and more particularly, to systems, methods and apparatus related to the use and formation of a resin impregnated carbon fiber.
- Concrete is used in many different types of construction projects, including, but not limited to walls, retaining walls, bridges, roadways, building foundations, etc. . . . . Concrete is a composite material that is composed of coarse aggregate bonded together with a fluid cement that hardens over time. Concrete may be poured off-site in forms to obtain a concrete structure in a desired shape and then transported on-site to be installed or it may be poured on-site in field constructed forms.
- It is known that most applications require one to reinforce concrete components using reinforcing members. In most cases, the reinforcing members are composed of corrosion susceptible steel, such as reinforcing bar or rebar. However, over time steel will degrade into iron oxide commonly referred to as rust. This degradation will eventually diminish the integrity of the rebar, and thus, the concrete structure. In many applications steel rebar may have a deformity, i.e., a deformed pattern that is designed to increase the friction between rebar and the material in which it is embedded.
- Recent attempts to overcome the shortcomings of steel rebar utilize reinforcing bars composed of carbon fibers. In general, carbon fiber based rebar is comprised of a plurality of unidirectional glass fibers that have been reinforced or thermoset with resin. The widely accepted properties of carbon fiber strands indicate that a member with a small cross-section will perform quite well in tension, but very poorly in shear. This is a fact that was experimentally confirmed during testing of a carbon fiber rebar (CF) with parallel carbon fiber strands. It was also found that a CF sample wherein all fibers are parallel with no surface deformations does not have sufficient bond strength with a cementitious material. This fact has since been confirmed by the American Concrete Institute (ACI) (440.6-3). The ACI goes as far as to require suppliers of fiber reinforced polymer (FRP) to provide the method by which the surface of the FRP is deformed.
- The deformed pattern may be replicated by “pinching” of the fibers prior to being set by the resin. However, this does not overcome the deficiencies of carbon fiber based rebar over steel rebar.
- The present invention is aimed at one or more of the problems set forth above.
- In a first aspect of the present invention, a reinforcing bar is provided. The reinforcing bar includes a plurality of strands and a deformity pattern. Each strand includes a plurality of carbon fibers. The strands having been impregnated with a resin and twisted forming a unified structure. The deformity pattern being formed within the unified structure by twisting the strands a predetermined number of times per linear foot of the unified structure and allowing the resin-impregnated unified structure to cure.
- In a second aspect of the present invention, a concrete structure is provided. The concrete structure includes a concrete member and a reinforcing bar. The concrete member is formed about the reinforcing bar while the reinforcing bar is under stress. The reinforcing bar includes a plurality of strands. Each strand includes a plurality of carbon fibers. The strands have been impregnated with a resin and twisted forming a unified structure. A deformity pattern within the unified structure is formed by twisting the strands a predetermined number of times per linear foot of the unified structure and allowing the resin-impregnated unified structure to cure.
- In a third aspect of the present invention, a method is provided. The method includes the steps of dipping a plurality of strands of carbon fibers in a bath of resin, pulling the strands of carbon fibers through an outgoing pair of rollers, as the strands leave the bath of resin, and twisting the strands of carbon fibers together to form a desired deformity pattern. The method further including the steps of allowing the resin to cure to form a reinforcing bar.
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FIGS. 1A and 1B are explanatory diagrams of parameters associated with an exemplary reinforcing rod associated with the present invention; -
FIGS. 1C through 24C are diagrammatic illustrations of a reinforcing bar, rod or member and/or structures used in the production of a reinforcing bar, rod or member, according to embodiments of the present invention; -
FIGS. 25-31 are diagrammatic illustrations of systems for allowing (building) components to attach to a concrete member, according to embodiments of the present invention. - With reference to the drawings, and in operation, the present invention is related to reinforcing bars and/or concrete structures with reinforcing bars. The reinforcing bars may be resin impregnated carbon fibers. In particular, the present invention may be related to systems, methods and apparatus, related to the formation and use of resin impregnated carbon fibers and/or methods and structures to apply tension or stress to reinforcing bars and/or methods or structures related to the production of concrete structures.
- In general, in one aspect of the present invention, a reinforcing bar composed of carbon fiber strands is provided. In another aspect of the present invention, a system and method for producing reinforcing bar composed of carbon fiber strands is provided. In still another aspect of the present invention, an apparatus for producing reinforcing bar composed of carbon fiber strands is provided. It should be noted that the terms reinforcing bars, reinforcing rods and reinforcing members may be utilized interchangeably.
- For a product to perform in a manner acceptable for this application, a given amount of surface deformation must be created during the manufacturing process. It is vital that this deformation creates enough mechanical bond with a cementitious material without increasing the shear in the fiber beyond an unacceptable yield point as the force is applied.
- The carbon fiber based reinforcing bar may be composed from a plurality of carbon fibers which are wound or twisted and then set in a resin. For example, in one embodiment, three strands of approximately 50,000 carbon fibers each are twisted together and then set (or thermoset) in a resin. The twist forms the deformations or deformation pattern that provides the friction between the rebar and the material in which the rebar is set. In one embodiment, the number of twists per a given length of the carbon fibers is predetermined and determined as a function of the number and size of fibers and/or strands of fibers.
- In one aspect of the present invention, each strand of carbon fibers may be composed from a tow of carbon fiber filaments. Each tow of carbon fiber filaments has an approximate predetermined number of carbon fiber filaments. Typical, tows may have 20,000; 30,000; 40,000, 50,000 or other approximate number of filaments. In general, the critical parameter is the overall strength of the resulting reinforcing bar, rod or member. The size of each filament and the number of filaments in different tows may differ. Therefore, based on the size of the filaments, the (approximate) number of filaments in each tow and the desired strength of the resulting member, rod or bar, the number of strands may be determined. It should be further noted that in some embodiments, a single tow may be used. In these embodiments, the single tow may be considered as including two or more strands. The two or more strands in the single two are twisted to create the non-uniform surface (see below).
- With reference to
FIG. 1A , the relationship between the number of twists (angle A) and the shear and tension loads is shown. From the diagram, it is clear that as the angle A increases due to increasing the number of twists per length of the fibers/strands, the shear load will increase as well [Shear=Tension(tan(A))]. Because the ultimate shear strength of a carbon fiber is considerably less than the ultimate tensile strength, the transfer of tensile load into shear load will become a limiting factor in the ultimate failure strength of the material.FIG. 1A illustrates the transfer of tensile load into shear load. This can be described as Measured Load*(sin(A)). It should also be noted that the tension in the fibers at this location is described as Measured Load*(COS(A)). - With reference to
FIG. 1B , there is a range in the number of twists per linear foot of carbon fiber wherein both the bond strength and the effective tensile strength are acceptable. It is within this range of twists per foot that all carbon fiber must embody in order to provide adequate mechanical bond, yet efficiently carry tensile load without inducing detrimental shear loads. - In general, the carbon fiber based reinforcing bar (rebar) is formed by pulling carbon fibers (under tension) through a resin bath and simultaneously, or shortly thereafter, twisting the fibers. The resin impregnated twisted carbon fibers are then left under tension while the resin cures.
- With reference to
FIGS. 1C, 1D, 1E, 1F and 1G , anapparatus 10 used in the formation of the carbon fiber based rebar, according to an embodiment of the present invention, is shown. Theapparatus 10 includes a bath housing 12 (which is shown in cross-section inFIGS. 1C and 1D ). Thebath housing 12 forms areservoir 14. In use, thereservoir 14 is filled with (uncured) resin. - As shown, the
apparatus 10 includes at least oneincoming roller 16, a series ofbottom rollers 18 and a pair ofoutgoing rollers 20. As shown by the arrows, aligned carbon fibers enter the apparatus 10 (from the left inFIG. 1C ) and are directed over theincoming roller 16. The fibers are then directed towards (into the resin bath) and around thebottom rollers 18. As the fibers leave the resin bath, the fibers are pulled through theoutgoing rollers 20. - In one embodiment, the carbon fibers are in the form of a strand of a plurality of carbon fibers. In a specific embodiment, three strands of 50,000 carbon fibers each are used.
- The three strands are pulled (or pultruded) through the resin bath simultaneously and after the fibers leave the resin bath, are twisted together. A more specific system and method is described below.
- First, the (dry) carbon fiber is pultruded through a series of
rollers FIG. 1E ). This step also ensures all of the fibers are aligned and that the cross-sectional area of the strand is within the acceptable range for the given (or intended) application. This step also ensures that the ratio of CF to epoxy is appropriate. The fibers are then left under a tension load which keeps all fibers aligned during curing. Generally, the block (shown inFIG. 1D ) will include a slot for each strand of fibers. - At this point, one end of the strand is fixed while the other end is twisted a predetermined number of times until it is within the range of twists per linear foot required for the intended application. After the twisting process is complete, both ends of the fiber are fixed and the strand is cured while remaining under tension. In one aspect of the present invention, the predetermined number of twists is determined as a function of the number and size of the carbon fibers and/or number and size of the strands of carbon fibers. In another aspect of the present invention, the predetermined number of twists may be determined as functions of the shear load required of the reinforcing rod, bar or member.
- The process of twisting this strand a pre-specified number of times results in a consistently non-uniform surface on the strand, which greatly increases the bond strength between the strand and a cementitious material. Without this added non-uniformity, the strand would possess little or no mechanical bond strength with cementitious materials. This is vital as the chemical bond between cement and the types of resin used is effectively non-existent.
- The strand is allowed to cure per resin manufacturer's suggestion, at which time it is ready to be used in production. Again, it is important to note that the strand remains under load during the curing process and that the twists are applied to the strand before the curing process begins.
- Another important factor in the manufacture of carbon fiber strands is predictability of performance. It is vital that the production process produces a strand that has consistent properties in both bond strength and ultimate tensile strength. The design values used for both of these factors should reflect the distribution of tested data points. That is to say that the design value should not be greater than the lower bound of the first standard deviation of the data set.
- After the resin impregnated carbon fiber based rebar has been cured, the rebar is ready to be used. In one aspect of the present invention, the carbon fiber based rebar may be brought under tension and a cement structure is formed around the pre-stressed fiber based rebar. Once the concrete has cured, the tension force from the rebar may be released.
- With reference to
FIGS. 2A-16 , asystem 50 for pre-stressing a reinforcing member within a pre-cast structure is shown. Thesystem 50 is particularly useful in pre-stressing a fiber base reinforcing member, such as a carbon fiber based rebar. A carbon fiber based rebar as detailed above with respect toFIGS. 1A-1D may be used. However, it should be noted that thesystem 50 may be used with any fiber based reinforcing bar. - In general, the
system 50 includes three main components: a grippingdevice 52, atension device 54 and a tension application sub-system 56 (A & B). - With particular reference to
FIGS. 10-14 , the grippingdevice 52 is used to provide an attachment to each end of a reinforcing member (or rebar) 58. In the illustrated embodiment, the grippingdevice 52 includes agripping tube 60, such as asteel tube 60. The grippingtube 60 has a calculated length, outer diameter and inner diameter. The parameters of thegripping tube 60 are determined to provide enough friction force between thegripping tube 60 and the reinforcingmember 58 given the tension force that needs to be applied while the pre-cast structure is being cast (see below). - The gripping
tube 60 is then filled with anexpansive grout 57. A cap 62 (seeFIGS. 13 and 14 ) with a pre-drilled hole in the center to guide the reinforcingmember 58 is then placed on the grippingtube 60.Cap 62 is multi-functional in that it contains theexpansive grout 57 as well as ensures that reinforcingmember 58 is concentric withgripping tube 60. The reinforcingmember 58 is then inserted through thecap 62 and into thegrout 57. Upon curing, theexpansive grout 57 creates a bond on both the reinforcingmember 58 and the inside of thegripping tube 60. This bond becomes a friction force upon the application of tension to the gripping tube 60 (one on each end of the reinforcing member 58) by thesystem 50. The friction force is a function of thegripping tube 60, e.g., the length and diameter(s) of thegripping tube 60, as well as thegrout 57. The grippingtube 60 is designed such that the friction force has a an ultimate strength greater than the tension force applied to the structure allowing the grippingtube 60 to be used as an attachment point for the tensioning process. It is important to note that the outer diameter of the grout tube is also limited by the designed distance between the reinforcingmembers 58. The outer diameter of thetubes 60 must be smaller than the centerline distance between the reinforcing strands to ensure that thetubes 60 for eachmember 58 do not inhibit one another. The same principal applies to the next part in thetension system 50, as well. - With particular reference to
FIGS. 3-9 , in the illustrated embodiment, thetension device 54 includes atension tube 64, allows the tension application sub-system 56 to quickly and easily be attached to thegripping device 52. Thetension tube 64, which may also be made of steel, has a specified length, outer and inner diameter such that the grippingtube 60 fits inside. The size of thetension tube 64 is determined such that the outer diameter of thegripping tube 60 is smaller than the inner diameter of thetension tube 64. The outer diameter of thetension tube 64 is also limited by the designed distance between the reinforcing members 58 (see above). That is, the outer diameter must be smaller than the centerline distance between the reinforcingmembers 58 to ensure that thegripping tubes 60 andtension tubes 64 for each strand do not inhibit one another. If this dimension were to become a limiting factor in the design of the reinforcing element location another tension application system would have to be designed to accommodate. - With particular reference in
FIGS. 3-9 , aninsert slot 66 is machined out of the top of thetension tube 64. Theinsert slot 66 allows the grippingtube 60 to be inserted quickly without compromising strength and reducing the amount of time necessary to remove the tension tub and reinstall the next new tension tube for reinforcement bar tensioning. Asmaller slot 68 allows themember 58 to also be inserted into thetension tube 64. One end of thetension tube 64 is (at least partially) closed (seeFIG. 9 ) and includes thesmaller slot 68 that allows the reinforcing strand to extend there-through when the grout tube is inserted into the tension tube. The opposite end to thetension tube 64 may be threaded (not shown) to allow the attachment of a threaded rod (see below) which connectstension device 54 to be connected to the tension application sub-system 56. Atension tube 64 may be used at both ends of each reinforcingmember 58 such that tension can be adjusted at either end. - With reference to
FIGS. 2A-2B and 17-24 , the tension application sub-system 56 includes a firsttension application apparatus 56A and a secondtension application apparatus 56B, one at each end of themembers 58. While only onetension application apparatus other apparatus members 58 may be adjusted at either end through the respectivetension application apparatus FIGS. 2A and 2B , twomembers 58 are shown. However, in the illustrated embodiment, fourmembers 58 are used. - Returning to
FIGS. 2A-2B and 17-24 , in the illustrated embodiment, eachtension application apparatus second assembly brackets removable brackets holes 76. Thetension application apparatus FIGS. 24A, 24B and 24C ) via the through holes 76. - The first and
second assembly brackets upright corner walls 72A-1, 72A-2, 72B-1, 72B-2. An interchangeable,removable plate 78 is provided between the first andsecond assembly brackets - For each
gripping device 52/tension device 54 pair, acoupling mechanism 80 is provided. Thecoupling mechanism 80 couples the respectivegripping device 52/tension device 54 pair to thetension application apparatus - In the illustrated embodiment, the
coupling mechanism 80 includes a first threadedrod 82. A first end of the first threadedrod 82 is threaded into a threaded aperture in the opposite end of thetension tube 64 of the tension device 54 (or otherwise coupled thereto). The opposite end of the first threadedrod 82 is threaded into one end of a respective load cell 84 (or otherwise coupled thereto). A second threadedrod 86 is threaded into a second end of therespective load cell 84. The opposite end of the second threadedrod 86 is inserted through a respective hole in theplate 78. Anadjustment nut 88 is threaded onto the opposite end of the second threadedrod 86. Rotation of theadjustment nut 88 controls the tension or force applied to therespective member 58. The tension imposed on themembers 58 causes a deflection (in either direction) within therespective load cell 84 which may be measured. - In use, once both ends of the tension application sub-system 56 are fixed, torque is applied to this
adjustment nut 88, resulting in a tension load being created in the reinforcing member(s) 58. Theassembly brackets plate 78 in place and are securely fastened to a true and secure surface with adequate structural capacities. Theassembly brackets members 58 under tension are level. An integral portion of the bulk head is the plate through which the threaded rods are inserted and the adjustment nut(s) 88 tightened against. The bulk head is designed such that thisplate 78 is removable for quick and easy alteration of the reinforcing strand locations. - In the illustrated embodiment, the pre-cast structure is formed using a form shape or
mold 90. Themembers 58 extend from the firsttension application apparatus 56A, through theform 90, to the secondtension application apparatus 56B. - The first step is to place all reinforcing
members 58 required for the pre-cast structure into theform 90 with thegripping tubes 60 in therespective tension tubes 64. Tension is then applied to the system via theadjustment nuts 88 and set to the proper torque to yield the correct value in tension. The cementitious material may be then poured into theform 90, around the reinforcingmembers 58. Tension is again verified before the cementitious material is left to cure. After the material is cured to the proper strength, the tension is systematically released at an equal rate among all reinforcingmembers 58. At this point, the grippingtubes 60 may be cut off (and disposed of) and the member is removed from theform 90. Theforms 90 can be cleaned and thesystem 50 prepared to begin the process over again. - The dimensions chosen for the prototype concrete member were governed by the dimensional, and load bearing requirements of the chosen construction system, the ACI cover depth requirements for reinforcing
members 58, and load capacity of reinforcingmembers 58. The ACI requires a minimum cover depth based on reinforcing member material and corrosive properties. That is to say there is a minimum distance from the surface of the concrete member to the closest surface of the reinforcing element. It is important to note that the cover depth for a composite fiber reinforcing element is less than that of a steel reinforcing element due to the difference in corrosive properties. This requirement shows that a member reinforced with a composite element could have a thinner cross sectional area than one reinforced with steel. For example the minimum cover depth for a steel member is 0.75″, therefore a member with a single 0.25″ reinforcing element could only be 1.75″ thick at the minimum. Whereas a composite member requires 0.375″ of cover therefore the same size reinforcing element could yield amember 1″ thick. It was this principal along with the engineered load rating for the member that would govern the dimensions chosen for the prototype composite reinforced, precast, pre-stressed concrete member. - In some applications, it is desirable to attach a different type of material, e.g., wood, to a precast concrete structure. For example, it may be desirable to use the precast cement structure as a girt on grade or “splashboard” in a post frame construction system. In such systems, different building parts must be attached to the precast concrete structure. In one aspect of the present invention, this method should increase versatility and facilitate quicker installation of fastener parts for optimal onsite field construction efficiency.
- In one aspect of the present invention, a
first attachment part 91A and asecond attachment part 91B may be embedded in a pre-stressed, pre-cast structure. Thefirst attachment part 91A has afirst body 93A. Thefirst body 93A has a first concrete structure facing side 95A and a first plurality ofattachment members 97A extending from the concrete structure facing side 95A. Thesecond attachment part 91B has asecond body 93B. Thesecond body 93B has a second concrete structure facing side 95B and a second plurality ofattachment members 97B extending from the concrete structure facing side 95B (see below). The first andsecond attachment parts compressible junction 99 therebetween. The pre-cast, pre-stressed concrete structure is formed from uncured cement. At least of a portion of the first andsecond 97B are embedded in the pre-cast, pre-stressed concrete structure. As discussed below, the first andattachment members 97Asecond attachment parts - With reference to
FIGS. 25-27C , asystem 100 includes one or more attachment parts or blocks, e.g., pieces of wood or lumber, being integrated with the precast cement structure. Concrete is a material that requires pre-drilling, so it may require additional work to attach pieces, building components to the cement structure. The use of an attachment part or block allows for the easy and efficient installation of building components, for example, ribbed steel panels. The panels may be bolted or otherwise fastened to the integrated piece of lumber. - With particular reference to
FIG. 25 , an exemplary block, e.g., piece of lumber, 102 is shown that may be integrated with the precast cement structure during the casting process (see above). As shown, theblock 102 includes a number ofshear studs 104 embedded therein. In the illustrated embodiment, an even number ofshear studs 104 are provided: one half of theshear studs 104 on one side of the center of theblock 102 and one half of theshear studs 104 on the other side of the center of theblock 102. In other embodiments, see for examples,FIGS. 26A-27C , an odd number ofshear studs 104 may be provided. - However, casting a
block 102 withshear studs 104 into a pretensioned concrete structure poses new problems that must be addressed in order to maintain a geometrically sound and acceptable member. - The
shear studs 104 may be cast into the concrete member during the pouring process. As discussed above, the applied tension on the rebar is released after the cement is cured. When the tension is released in the cured, pre-tensioned, precast concrete structure, a compression force (seeFIG. 25 ) is transferred causing the structure to decrease in length in an incremental amount varying by the tension applied, the cross-sectional area of the member, and its composition. - This poses a problem for any material that is cast into the pre-tensioned, precast concrete structure as the item cast into the structure must have the ability to be slightly compressed at a rate similar to the concrete structure. If the item cast into the concrete member has dissimilar elastic properties or unsymmetrical geometric properties, the resulting internal stresses can yield unacceptable deflection (see
FIG. 28 ). - With reference to
FIG. 29 , in one aspect of the present invention, this issue may be solved by creating a relief cut in theblock 102 or provide a plurality ofblocks 102 with a relief or space. The relief may be filled with acompressible material 108 casting the pre-castconcrete structure 106. This “compressible void” acts as a cushion for theblocks 102 to compress along with the precastconcrete structure 106. - Even with the “compressible void”, a certain amount of moment is applied to the block(s) 102 due to the shear transfer facilitated by the
shear studs 104 and the fact that they are a distance away from the centerline of the blocks 102 (seeFIG. 25 ). While this moment is a function of the compression force, the size of theblocks 102, and the frequency ofshear studs 104, the stress and deflection in theblock 102 is a function of its moment of inertia and the moment caused by the compression. As the moment of inertia is related to the cross-sectional area and length, the relationship is such that with all other variables equal, ablock 102 with less length will yield less deflection. This relationship may be used to determine the optimal distance between “compressible voids” for each value of pretension force. This inverse relationship is such that higher pretension values require smaller distance between “compressible voids”. - In one aspect of the present invention, a method is provided. Stress is applied to a reinforcing member. The first and second attachment parts are positioned at predetermined positions relative to the reinforcing member. The first attachment part has a first body. The first body has a first concrete structure facing side and a first plurality of attachment members extending from the concrete structure facing side. The second attachment part has a second body. The second body has a second concrete structure facing side and a second plurality of attachment members extending from the concrete structure facing side. The first and second attachment parts are spaced apart forming a compressible junction. A concrete form is positioned at a predetermined location about the reinforcing member and the first and second plurality of attachment members. Uncured cement is poured in the concrete form. The uncured cement encases at least partially, the reinforcing member and the first and second plurality of attachment members. Then, the cement is allowed to cure and the stress is released from the reinforcing member.
- It should be noted that the steps of this method do not necessarily need to be performed in the order listed above. For example, the step of positioning the first and attachment parts at predetermined positions relative to the reinforcing member may be performed before or after the uncured cement is poured into the form.
- In another aspect of the present invention, a method to attach the block or
lumber 102 to the precastconcrete structure 106 is provided. As concrete does not chemically bond with wood, asystem 100 of mechanical anchoring is required. In the illustrated embodiment, a series ofshear studs 104 is placed in the lumber or block 102. A portion of the length of eachshear stud 104 remains exposed. The cementitious material is then cast around theshear studs 104, thereby bonding the lumber to the precastconcrete structure 106. The spacing of theshear studs 104 is critical and varies depending on the amount of load that is required to be transferred from the block(s) 102 into the precastconcrete structure 106. The frequency of theshear studs 104 may be increased beyond the minimum requirement to allow the cement structure(s) to be cut in any location while maintaining adequate shear transfer. - The method of applying
shear studs 104 to the underside of a block orwooden member 102 before the member is cast in cementitious material is shown inFIGS. 26A-27C . In the illustrated embodiment, the spacing between studs is 4″ though this is subject to change with corresponding structural loads to be transferred into the precastconcrete structure 106. The size of thelumber block 102 depicted is a 1.5″ cross sectional-square though this is also subject to change dependent on the application. - It is important to note that the
shear studs 104 in theblock 102 should be placed such that theshear studs 104 do not interfere with any reinforcing elements that may be within the cementitious material. It is also important to note that the shape of the wooden block is not restricted to square. Any shape that suits a particular application as long as there is a flat base for the installation of theshear studs 104 will be acceptable. Theshear studs 104 should be comprised of a corrosion resistant material. For example,FIGS. 26A-26C illustrate ablock 102 having a square cross-section. In particular, theblock 102 is composed of a 1.5″-1.5′ treatedlumber block 102 having a maximum length of 24″. Theshear studs 104 are corrosive resistant fasteners having a 4″ spacing. InFIGS. 27A-27C , theblock 102 has a groove (as shown) that may be useful for fastening building components thereto. - The spacing of the “relief cuts” and resulting “compressible void” is subject to change in pretensioned elements under differing loads.
- In an alternative embodiment, the first and second attachment parts may be made from metal. For example, an integral piece of galvanized steel or
metal plate 200 may include with the concrete structure to facilitate an easy installation of building components. However, casting a section of galvanized steel 200 (FIG. 30A ) into a pretensioned concrete structure poses new problems that must be addressed in order maintain a structurally sound member. - With reference to
FIGS. 30A and 30B , asystem 200 includes one ormore metal plates 204 that are integrated with the precast, pre-stressedconcrete structure 210. This allows for the easy and efficient installation of building components, for example, ribbed steel panels. - In one aspect of the present invention, the
system 200 includes a plurality ofplates 204. In the illustrated embodiment, eachplate 204 includes anupright member 205 to which building components may be fastened. Eachplate 204 also includes a slot andgroove mechanism 206 that provides a slip joint betweenadjacent plates 204. The slot andgroove mechanism 206 includes atab 206B and a plurality of offsethorizontal members 206A which are offset to form a slot for receiving atab 206B from anadjacent plate 204. Eachplate 204 also includes a plurality of fins 208. The fins 208 are embedded in the uncured cement that forms the precast,pre-stressed cement structure 210. In the illustrated embodiment half of thefins 208A, are deflected from theupright member 205 at a predetermined angle. The other half of thefins 208B are deflected from theupright member 205 at an opposite angle. Further, in the illustrated embodiment each fin 208 has a hole. - When the tension is released in the cured, pretensioned, precast
concrete structure 210, theconcrete structure 210 will decrease in length in an incremental amount varying by the tension applied and the cross-sectional area of thestructure 210. This poses a problem for any material that is cast into the pretensioned, precastconcrete structure 210 as the item cast into the item must have the ability to be slightly compressed. If the item cast into the precastconcrete structure 210, and the member is not compressible at a rate similar to theconcrete structure 210 then the resulting internal stresses can cause unacceptable deflection of the entire member. - This issue is addressed in several ways. The first method involves creating a slip joint between sections of
metal plates 200. This allows smaller pieces of galvanized metal to be used and allows them to “slip” a small amount at the joints where the two pieces meet. The second method for solving this issue involves leaving a gap between the pieces of galvanized metal fin and filling said gap with a compressible material. This “compressible void” allows themetal plates 200 to move closer together (or further apart) as tension is released thus relieving a portion of the internal stress in the material yielding a finished product that is suitable for the intended use. - The same principal used to describe the moment to length relationship of block(s) 102 in section [0044] can also be applied to
plates 200. That is to say that there is a moment applied uponplates 200 as their contact with the compression force is a distance away from the centerline ofplates 200. While this moment is a function of the geometry of tabs 208, the compression force of the reinforcing elements and the cross sectional geometry of theplate 200, the stress and deflection of said plate is a function of its moment of inertia and the moment induced by the compression. As the moment of inertia is related to the cross sectional area and the length, it could be shown that if all other variables were equal, aplate 200 of a shorter length would yield less deflection. This relationship along with the determination of an acceptable deflection range may be used to find the optimal length of theplate 200 as well as optimal dimensions for the “compressible voids” or “slip joints.” This same relationship could also be used to show that a higher pre-tensioning load would require a decrease in the length ofplate 200 in order to keep deflection within said acceptable range. - The second problem comes with developing a method to attach the galvanized steel or “
plate 200” to the precast member. While the galvanized steel will chemically bond to the cementitious material to a certain extent, a level of mechanical bonding is required. This is often achieved by creating a surface on the material that is non-uniform. A non-uniform surface will create small shear faces in the cementitious material along the length of the bonding surface. In the case of the galvanizedsteel fin fins - It is important to note that fins 208 or
plate 200 is made from a corrosive resistant material or may be coated with a corrosive resistant substance or protection layer. Whenever a steel sample is cast within a concrete member there is the potential that the steel will deteriorate over time causing the concrete sample to crack, spall and eventually fail. This is caused in part by chloride ions within the concrete sample that break down the protective layer around the steel that is created during the early stages in the concrete curing process. Once this protective layer is gone, there is opening for oxidation of the iron ions within the steel which yields iron oxide or what we refer to as rust. The process of galvanization adds a protective layer of zinc over the entire steel part. Once within the concrete this protective zinc coating propagates out, creating an even broader barrier against the chloride ions and oxidation. - In another aspect of the present invention, a method of producing a galvanized
metal plate 200 that can be cast into a pretensioned, precast concrete member and that facilitates the attachment of said structure to other building components is provided. Thegalvanized plate 200 is of an altered cross sectional geometry such that the shape adds an increased level of mechanical bonding with the cementitious material it is cast into. Thegalvanized plate 200 is of a specified length which is varied in relation to the application and pretensioning loads used in given member. The relationship is such that a higher pretension load will require a shortermaximum length plate 200. The ends of eachplate 200 are shaped in such a manner that they fit together as a “slot and tab” mechanism. This allows theplate 200 andcementitious member 210 to move linearly with respect to one another without moving in the shear direction. - In order to employ a precast
concrete member 106 as a splashboard in a construction system, a method of attachment for all building parts must be developed. This method should increase versatility and facilitate quicker installation of fastener parts for optimal connection efficiency. It was determined that an integral nailable substrate could be included with the concrete member to facilitate an easy installation of, e.g., steel panels or exterior sheathing along with the corresponding trims and accessories. Casting a section of a nailable material withattachment members - This poses a problem for any material that is cast into a pre-tensioned, precast concrete member as the item cast into the member must have the ability to be slightly compressed at a rate similar to the concrete member. If the item cast into the concrete member has dissimilar elastic properties such that the center of the pre-stress load is not concentric with the center of rigidity of the combined member, the resulting internal stresses can yield unacceptable deflection.
- The relationship between tension force, modulus of elasticity and overall length change of the member is such that a higher force with and equal Young's Modulus will yield a larger decrease in length. Furthermore, if the tension force is equal and the modulus of one portion of the member is lower than another portion of the member, the section with a lower modulus will decrease in length by a greater amount. If we combine these two ideas it could be stated that if a member has a large variance in Young's Modulus, the tension force could be varied through the plurality of reinforcing elements such that the overall decrease in length of the member would be consistent throughout.
- A method to attach the nailable substrate to the precast concrete is provided. As concrete will not chemically bond with many nailable materials, a system of mechanical anchoring is required. It was found that a series of attachment members, e.g., shear studs, could be placed (attached, screwed, nailed, driven, etc. . . . ) in the nailable substrate with a portion of the length of said stud remaining exposed. The cementitious material is then cast around these studs bonding the nailable member to the cast concrete member. The spacing of these studs is critical and varies depending on the amount of load that is required to be transferred from the nailable substrate into the precast concrete member. Frequency of studs is increased beyond the minimum requirement to allow members to be cut in any location while maintaining adequate shear transfer.
- The method of applying studs to a face perpendicular to the intended nailing face of a nailable member before said member is cast in cementitious material is illustrated in
FIG. 31 . The spacing between studs in this figure is 4″ though this is subject to change with corresponding structural loads to be transferred into the concrete member. The size of the nailable member is a standard nominal “2×4” though this is also subject to change dependent on the application. - It is important to note that the studs in the nailable member should be placed such that they do not interfere with any reinforcing elements that may be within the cementitious material. It is also important to note that the shape of the nailable member is not restricted. Any shape that suits a particular application as long as there is a flat base for the installation of the studs will be acceptable. The shear studs used should be comprised of a corrosion resistant material.
- As is shown in
FIG. 31 and described herein, ifModulus 1 is significantly less than Modulus two, a higher tension load can be placed on the lower of the two reinforcingelements elements element - This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Other aspects and features of the present invention can be obtained from a study of the drawings, the disclosure, and the appended claims. The invention may be practiced otherwise than as specifically described within the scope of the appended claims. It should also be noted, that the steps and/or functions listed within the appended claims, notwithstanding the order of which steps and/or functions are listed therein, are not limited to any specific order of operation.
- Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
Claims (22)
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US15/979,256 US20180328039A1 (en) | 2017-05-15 | 2018-05-14 | Systems, apparatuses, and methods related to fiber strands used in reinforced concrete |
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US15/979,273 Active 2038-10-22 US10843378B2 (en) | 2017-05-15 | 2018-05-14 | System and method for applying stress to a reinforcement member |
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US10576658B2 (en) * | 2017-05-15 | 2020-03-03 | Morton Buildings, Inc. | System and method for embedding substrate in concrete structure |
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