Patent Application
20240052635
The invention relates to a tubular reinforcement element formed in a grid shape from a continuously arranged intersecting yarn, wherein the intersecting portions of the at least one yarn are interconnected by a cross-connection and methods for producing thereof. The invention further relates to a global reinforcement for a concrete component, comprising at least one reinforcement element, the use of a reinforcement element, and a concrete component. The invention further relates to a program file for executing a method.
DE 10 2015 100 386 A1 describes a reinforcement element that is designed as a bar and is essentially one-dimensional. The bar has filaments embedded in a matrix material. The filaments provided are aligned in a tensile direction and are entirely surrounded by a mineral matrix material. The matrix material is fine concrete or a suspension comprising fine cement. The use of high-performance reinforcement elements of this type, in which carbon fibers are used and which have strengths in the range of 2000-4000 N/mm2, results in the need for force transmission between the reinforcement elements and the matrix material concrete. The high forces of the carbon reinforcement must be introduced into the concrete in a targeted manner to exploit the carbon fibers' potential efficiently. In this way, short anchorage lengths are also possible with the use of carbon elements in order to be able to guarantee economical use.
In the case of bars, for example, carbon bars, an attempt is made to improve the bond in the same way as with reinforcement steel using suitable surface profiling to ensure a sufficient bond. Various concepts are pursued to achieve a composite load-bearing capacity since a ribbed structure, which is common in steel reinforcement elements, is not possible or inefficient due to the anisotropy of the carbon fibers. Therefore, carbon bars are provided with an additional sand layer, for example, which can improve the adhesive and frictional bond compared to a smooth carbon bar. Other variants for carbon bars include the application of a subsequent rib structure, for example, made of synthetic resin, the subsequent wrapping of individual fiber strands, shape variation of the carbon bars in the production process to improve the bond, or subsequent milling to produce opposing ribs, also known as grooves.
Various elements are used as reinforcement for carbon or textile concrete. Both grids, for example, biaxial, multiaxial, or three-dimensional grids, and bars can be used. Such a grid, which forms a textile reinforcement for a concrete component made of yarn free of polymer binders, is described in DE 10 2016 100 455 A1, including a method and a device for its production. A laying device is provided, in which a positioning device or a laying robot is arranged movably in two dimensions relative to a yarn delivery device. The laying device is designed to form a tension fabric of yarn free of polymeric binders within a base frame. The base frame has yarn holding devices in the area of outer edges of the base frame and/or of recesses. The yarn holding devices also form deviation points for the yarn.
Other three-dimensional structures are known from prior art. For example, the DE 10 2014 200 792 B4 and EP 2 530 217 B1 publications describe flat structures which form a textile reinforcement structure using a spacer structure or as a spacer fabric or knitted fabric that has already been produced in three dimensions. Furthermore, a grid girder is known from the DE 10 2016 124 226 A1 publication, whose implementation is also based on a flat textile reinforcement element formed by rows of thread- or yarn-shaped individual elements, which serve as sections of a chord and struts. However, in all cases, the large-scale structure is not suitable to effectively replace discrete reinforcement elements such as rebars or reinforcement cages.
The solution from the DE 10 2012 101 498 A1 publication also provides for a textile grid that the matrix material can easily penetrate. Furthermore, the textile grid, which is initially produced as a flat structure, is to be formed into a U-shape, thus obtaining a discrete reinforcement element. However, the open U-shape has a lower stiffness than closed cross-sectional shapes.
The publication WO 98/09042 A1 discloses a tubular reinforcement element that is grid shaped and in which the intersecting sections are joined together. The tubular reinforcement element consists of thermoplastic fiber-reinforced strips joined by spot welding at the intersections. Alternatively, tubes made of fiber strands are provided, later drawn onto a core mold, laminated, and cured. However, the load is taken up exclusively via the fiber strands in the tensile direction, insofar as there is a load component in this direction; the use of other mechanical effects is not envisaged.
The invention relates to a tubular reinforcement element (1) that is formed in a grid shape from a continuously arranged intersecting yarn (2), wherein the intersecting sections (3) of the at least one yarn (2) is connected to one another by a cross-connection. According to the invention, the cross-connection of the yarn (2) is implemented by a material means or a mechanical means, wherein the means determines the shear elasticity of the cross-connection, the elasticity during the counteractive pivoting movement of the crossing sections (3) about their crossing point in the cross-connection, and thereby determines the extensibility of the reinforcement element (1) in the direction of a longitudinal axis, a higher shear elasticity being accompanied by higher extensibility. The invention further relates to a method of producing the tubular reinforcement element (1) by weaving, braiding, or winding the grid structure from a yarn (2). Other aspects of the invention relate to a global reinforcement, a use, a concrete component, and a program file.
Thus, it is an object of the present invention to provide a tubular reinforcement element formed in a grid shape using the at least one continuously yarn arranged in an intersecting manner and providing improved bonding with a matrix material, which further provides improved load reserve in the event of overload.
The problem is solved by a tubular reinforcement element formed in a grid shape from a continuously arranged intersecting yarn, wherein a cross-connection interconnects the intersecting sections of the at least one yarn. The diameter of the reinforcement element along its length may be constant or variable. According to the invention, at least one continuously arranged intersecting yarn is provided from which the mesh is formed. Alternatively, several yarns are used, each of which is fed from a spool during the production of the reinforcement element, and wherein one yarn at a time forms a “grid bar” of that grid which forms the shell surface of the tubular reinforcement element. According to a further alternative, it is envisaged to use only one yarn from a single spool and to deflect and lay it down in such a way that the I shape is also formed. In that case, the yarn crosses with itself in different layers. According to a preferred embodiment, a curable material, such as a resin, provides stability to the tubular reinforcement element after the grid has been formed.
The crossing sections of the yarn are connected to each other at their crossing point in such a way that the shear elasticity of the cross-connection, the elasticity during the counteractive pivoting movement of the crossing sections about their crossing point in the cross-connection, determines the ductility of the reinforcement element in the direction of a longitudinal axis, wherein a higher elasticity is accompanied by a higher ductility.
According to the invention, the yarn is cross-connected by a material means or a mechanical means, wherein such means adjust the shear elasticity of the cross-connection, the elasticity at the counteractive pivoting movement of the crossing sections about their crossing point in the cross-connection, and thereby determine the extensibility of the reinforcement element in the direction of a longitudinal axis, wherein a higher shear elasticity is accompanied by higher extensibility.
The cross-connection has such a shear elasticity that the reinforcement element is equipped for intended extensibility in the direction of the longitudinal axis and at the same time transversely to the longitudinal axis, in the transverse direction. The shear elasticity describes the elasticity during the counteractive or pivoting movement of the crossing yarns or yarn sections about the crossing point in the cross-connection. Higher shear elasticity results in higher ductility of the reinforcement element, wherein the deformation occurs in the direction of the longitudinal axis and, in the sense of constriction, at the same time transversely to the longitudinal axis, in the transverse direction. If the reinforcement element is used in a component, the defined ductility of the reinforcement element ensures good ductile behavior of the component, which is associated with a high level of additional safety.
The grid form is preferably woven, braided, laid, or wound, although other influencing factors naturally lead to the ultimately adequate ductility or stiffness. As a result, concrete structural modules are still held together even when overloaded. The influencing factors also include the matrix material in which the reinforcement element is embedded and with which it is filled. Furthermore, the dimensions of the reinforcement elements are essential.
Advantageously, the crossing sections of yarn in area of the grid intersections are joined by material means, such as bonding or welding, or mechanical means, such as sewing. The properties of these connections, particularly their shear strength against torsion or pivoting of the crossing yarn sections against each other, fundamentally and substantially determine the shear strength and, via this, the ductility or stiffness of the reinforcement element.
The bonding of the grid intersections, the stabilization of the tubular shape, and the load transfer to the internal fibers can be achieved in different ways. According to a first embodiment of the process according to the invention, stabilization is achieved by means of fixation by a curable resin. This can be applied after yarn deposition, the production of the tubular form, or after the yarn is impregnated with the curable resin before yarn deposition. The impregnation can occur immediately before the yarn is deposited or the yarn is supplied already impregnated, in which case the resin contained must be prevented from undesirable premature curing.
Reactive resins, such as epoxy resin, or aqueous dispersions, e.g., based on acrylate or styrene butadiene, are preferred as curable matrix material.
According to a second embodiment of the process according to the invention, the yarn, as a hybrid yarn, is additionally provided with thermoplastic and thus thermally activated synthetic fibers in addition to the load-bearing fibers. The action of heat can activate these by melting and, after curing, ensuring that the yarn's fibers suitable for load transfer are bonded to one another so that the same effects are achieved as when a curable resin is used.
One embodiment of the reinforcement element, according to the invention, provides that a matrix material is provided inside the reinforcement element and that a further longitudinal reinforcement, at least one electrical conduit, at least one fluid conduit and/or an empty tube into which one of the aforementioned conduits or the longitudinal reinforcement, with or without prestressing, can be subsequently inserted, be embedded therein.
According to an alternative embodiment of the reinforcement element invention, a hollow inner space is provided in the reinforcement element, and it is kept free of the matrix material used in the concrete component. Inserting a strand or other load-bearing element into the interior of the reinforcement element through the hollow space provides global reinforcement that extends beyond the individual reinforced concrete structural elements and can carry forces as an additional safeguard in the event of failure.
In the following, global reinforcement is also referred to as a form of application of the tubular reinforcement element, as distinct from local reinforcement. Based on conventional textile concrete technology, reinforcement structures are used to provide a primary reinforcement with which the stresses can be safely absorbed under the relevant service load conditions, for example, for a reinforced concrete structural element. In addition, higher-level global reinforcement, for example, strands with a net-shaped sheathing, which can be coiled, braided, woven, or laid, provide high load reserves under extreme conditions. They are designed with very high ductility so that when they are activated, a high ductility component is produced. Thus, the global reinforcement ensures that the cohesion of the entire load-bearing structure is maintained even after a possible failure of the local base reinforcement due to a possible extreme load. The global reinforcement lies on the load paths of the local reinforcements and acts as an additional safety element in case of overload. Under normal load conditions, the global reinforcements increase the stiffness of the concrete component.
It has proved advantageous for specific applications if the wall of the empty tube or the hollow space in the tubular reinforcement element is designed to be airtight and water-tight so that gases or liquids can be transported or passed through it. Further sealing of the tube wall is then unnecessary. Other functional coatings are optionally provided. For example, an inner and/or outer coating can be applied to control or at least partially prevent bonding to a surrounding matrix material alternatively to improve bonding. In this way, the stiffness of the reinforcement and thus that of the component can be adjusted as required. The stiffness is highest with stronger bonding, particularly when the matrix material can enclose the yarn.
According to the invention, in an advantageous embodiment of the reinforcement element, the latter is electrically conductive due to the electrical properties of the material used, such as carbon fibers, or if the material is provided with an electrically conductive coating. In this case, electrical energy or electrical signals can be conducted directly through the reinforcement element. However, electrical heating can also be achieved via the electrical conductors formed in this way, especially if the resistance is set appropriately. To control the heating generated, a matrix material that has a temperature-dependent variable electrical resistance can fill the interior of the reinforcement element. In addition, according to an advantageous further development of this embodiment, it is provided to fill the interior of the reinforcement element with an electrolyte in order to achieve short-term energy storage by a capacitor effect. An electrically conductive coating can also adjust, control, or change the electrical properties.
Another aspect of the present invention relates to a method of producing a reinforcement element as previously described. The fabrication is performed by weaving, braiding, or winding the grit structure from one yarn, preferably from several yarns. According to the invention, it is provided that the intersections of the at least one yarn are fixed by gluing, welding or sewing. In this way, the intersecting yarns can be restricted in their mobility relative to one another in a defined manner, and thus the mechanical properties, in particular the shear elasticity of the reinforcement element as a whole, can be controlled or adjusted.
One embodiment of the process, according to the invention, seeks to create a hollow space inside the reinforcement element embedded in the matrix material. In particular, the hollow space is created in such a way that an airtight hose is inserted into the interior of the reinforcement element, and the hose is expanded by applied fluid pressure to a diameter corresponding to the diameter of the hollow space to be created. The matrix material, particularly concrete, is then applied, and after the matrix material has cured, the fluid pressure in the hose is released. The process, according to the invention, is not limited to a hose with a circular cross-section; rather, any cross-sectional shape that corresponds to the desired internal geometry can be considered.
A further embodiment of the process, according to the invention, serves to provide a load reserve. The interior of the reinforcement element is initially filled with a cured matrix material. If this breaks under overload and the fracture point is stretched, a constriction is formed and the reinforcement element simultaneously activates a load reserve by developing a ductile load-bearing property. The stretching and the resulting deflection of the structure provides an announcement of structural failure caused by exceeding the ultimate load, which is required in civil engineering.
The task of the invention is also solved by a global reinforcement for a concrete component, comprising at least one reinforcement element as described above. According to the invention, for this purpose, the at least one reinforcement element is connected utilizing at least one connecting element to a local reinforcement, such as a reinforcement mesh, or an additional reinforcement element as described above, either directly or at a distance. An element for cross-component force transmission is guided through the empty tube or the hollow space in the reinforcement element so that the concrete component is connected to a further concrete component in a force-conducting manner. The connecting element is advantageously designed in the form of a strip loop or spiral, preferably including an insertion hook to facilitate the installation of the spiral connection element.
The global reinforcement is a reinforcement that comprises the reinforcement element according to the invention, designed as a net-shaped, braided, woven, wound, or mesh tube, in particular, based on carbon fibers, and additionally, the integrated longitudinal reinforcement of carbon bars or strands. The global reinforcement is preferably located on the inner sides of the concrete layer, thus in the component's interior. An alternative arrangement of the global reinforcement is a position alternating from the inner to the outer surface and/or vice versa. For this purpose, the reinforcement element is connected to the local reinforcement via connecting elements, for example, designed as a strip loop or spiral, and it is filled during concreting with an expandable, flexible material that can be removed later as described above. The hoses are entirely encased in concrete during production.
Subsequently, after concreting and production of the elements, the filler material can be removed from the tubes. After the elements have been assembled and connected, the carbon bars or strands are pulled through the void spaces, making the global reinforcement functional. Finally, grouting of the remaining voids can be done with a grout, creating a bond between the carbon bar or strand and the concrete bearing layer and improving the overall bearing behavior of the system. The bond between the carbon strands and the braided tube surrounded by fine concrete, according to the invention, significantly influences the load-bearing behavior.
While carbon strands have a material-related high stiffness, strength, and brittleness, the reinforcement element, according to the invention, is designed as a braided, woven, coiled, or mesh tube, in particular made of carbon fibers, which is above all comparatively flexible and ductile. The interaction of the two reinforcements, the local reinforcement, and the global reinforcement, ensures the required ductility of the composite material and guarantees the announcement of structural failure required in civil engineering when the ultimate load is exceeded. The maximum utilization of the load-bearing reserve of the material is accompanied by large deformations, which indicates the overload that has occurred and thus announces the imminent complete structural failure.
Particularly advantageous use of the reinforcement element according to the invention thus arises when an element is passed through the empty tube or the hollow space as cross-component force transmission and in particular for force transfer, for example, a bonded or unbonded bar, roving, or strand. This allows the concrete component to be connected to another concrete component and creates a global reinforcement as described above.
Another aspect of the present invention relates to the use of a reinforcement element, as previously described, as a guide channel for a supplementary reinforcement, in particular the global reinforcement, but also as a prestressing duct, ductility reinforcement, as a fluid conduit or as a duct for a fluid conduit, a power conduit or a conduit for other for electrical functions, such as a control conduit. In particular, the guide channel accommodates an axially loaded reinforcement element within itself. This represents an embodiment of the global reinforcement and is used in the event of failure of the concrete component or of the relevant component.
Likewise, the reinforcement element can accommodate prestressed and permanently loaded reinforcement. It then serves as a prestressing duct. When used as ductility reinforcement, the mechanical properties of the reinforcement element itself come into play in that it can develop a load reserve when overloaded under a high degree of deformation. Furthermore, the hollow inner space is suitable for accommodating the various conduits throughout the concrete component across the boundaries of the concrete structural elements.
The invention also relates to a program file for executing a method according to any one of claims 8 to 10 for execution in a yarn laying device or a computer controlling a yarn laying device. The program file also comprises a procedure or algorithm for automatically depositing yarn.
Based on the description of embodiments and their illustration in the accompanying drawings, the invention is explained in more detail below. It shows:
Different yarns cross each other in the preferred embodiment and are each taken from a separate bobbin. Alternatively, however, it is also provided that only one yarn is taken from a single bobbin and is wound into the desired manner (cf.
In the winding technique as shown in embodiment b), all yarns 2 of the first winding direction lie under the yarns 2 of the second winding direction. The stability corresponding to the effect of a woven fabric according to the embodiment a) is not given, and the intersecting section 3 must therefore be secured in another way, particularly with a material agent (for example, chemically by bonding).
The same type of winding as in letter b) is also shown in the embodiment in letter c), but here supplemented by a connection of the intersection sections 3′ by sewing stitches. Accordingly, this is a mechanical connection of the intersecting sections 3′. Nevertheless, this connection can be supplemented by securing it with a material agent. In any case, the type of connection, in particular its strength and stiffness, influences the ductility of the reinforcement element 1.
The previously described coating 5 is used in the variants shown in letters c) and d). In addition to controlling the strength of the joint or controlling the application of force, other effects can also be achieved with it, for example electrical conductivity can be improved or achieved or deterioration of the used yarns 2 can be prevented, which could be caused by contact with the matrix material 4 or 6.
The use of the inner matrix material 6 also enables the integration of additional functions such as (but not limited to) those shown in letters e) to g). These include the installation of flexible conduits for liquids, gases, or electricity or of data conduits. Furthermore, additional elements for force transmission can be installed therein, thus forming a global reinforcement. Additional elements can be bars, rovings, cables or strands with or without prestressing, bonded or unbonded.
The embodiment of a global reinforcement shown does not require an additional element, such as a strand arranged inside the reinforcement element 1, and exhibits a desirably high ductility.
The illustration, according to the letter a) shows the possibilities of producing a profiled hollow space inside the reinforcement element 1 according to the invention. This is done either by a rubber profile 24′ or by a hose 18′, which can be pressurized inside utilizing a fluid (the process sequence is also described in
Correspondingly, the illustration under letter b) shows how a hollow space with a circular cross-section is produced. A hose 18 with a corresponding circular cross-section or a rubber profile 24 with the same cross-section are used for this purpose.
For the production of the global reinforcement for high load reserves under extreme conditions and overload, high-level global reinforcement strands are introduced into the finished concrete component composed of the concrete structural modules, for example, strands with a net-shaped sheathing, which can be coiled, braided, woven or laid. The continuous hollow space in reinforcement element 1 is used for this purpose, so a very high ductility results from the activation of the component's high ductility. Thus, the global reinforcement ensures that the cohesion of the entire load-bearing structure remains even after a possible failure of the local base reinforcement due to a possible extreme load.
The global reinforcement consists of tows, i.e., very thick carbon fiber strands with fiber strand diameters of, for example, 15 mm2 (>3000 kN), which span the entire building structure following the load path. In the event of a sudden overload and failure of the primary reinforcement, the local reinforcement, or the base reinforcement, the tensile forces to be absorbed are transferred to the global reinforcement (or secondary reinforcement), which then ensures the load-bearing capacity of the overall structure.
As an alternative to passing global reinforcement strands through the reinforcement element, the reinforcement element can also be designed to continuously extend over the concrete structure modules and cast in concrete. Global reinforcement is also achieved in this way.
In order to announce a possible structural failure at an early stage and by a clearly noticeable increase in deformation, the global reinforcement is surrounded by a textile structure in the form of a tubular interwoven, woven or otherwise produced reinforcement element according to the invention with axially integrated rovings, from now on also referred to as ductility reinforcement, which absorbs loads of the supporting structure with an apparent increase in deformation. Taking advantage of the high energy absorption capacity of the ductility reinforcement at large deformations, high efficiency can be achieved with low resource input so that significantly smaller yarn cross-sections (<5 mm2) are required for this purpose than with global reinforcement, which also requires separate additional elements such as tows introduced into the reinforcement element according to the invention.
The movements as required for the installation of the connection element 12 are indicated in more detail by the reference signs 15 for the rotation movement and the resulting longitudinal movement 16 in the screwing-in direction using arrows.
An alternative embodiment of the concrete component 20, according to the invention, provides that the reinforcement element 1 itself combines several concrete structural modules 21. For this purpose, it is necessary to cast the individual concrete structural modules 21 together, and after they have been joined together, at the same time cast concrete on the reinforcement element 1, which runs over several concrete structural modules 21. It thus connects the concrete structure modules 21 to each other and the edge connections 40. Additional securing is still possible.
Further shown is a shear reinforcement 36, a structural shaped reinforcement made of a textile grid-like structure, which both engages the two shells of the sandwich element and provides the connecting and spacing structure between the two shells.
Furthermore, the tubular reinforcement element 1 is provided, which enables the introduction of high forces in the intended direction and transfers them. The reinforcement element 1 can also transfer forces across several concrete structural modules 21. For this purpose, a strand 9 is introduced into the interior of the reinforcement element 1. The strand 9 connects several concrete structural modules 21 to each other and can globally transfer forces across the concrete structural modules 21 or the concrete component 20, for example, in the event of a failure of the edge connection 40, thus ensuring the function of a global reinforcement.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 126 609.2 | Oct 2019 | DE | national |
This application is the U.S. national stage of International Application No. PCT/DE2020/100853, filed on 2020 Oct. 2. The international application claims the priority of DE 102019126609.2 filed on 2019 Oct. 2; all applications are incorporated by reference herein in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2020/100853 | 10/2/2020 | WO |
