CN111206721A - Fastening element for reinforcing elements in the construction industry and method for introducing compressive stresses into an element - Google Patents
Fastening element for reinforcing elements in the construction industry and method for introducing compressive stresses into an element Download PDFInfo
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- CN111206721A CN111206721A CN201911156229.3A CN201911156229A CN111206721A CN 111206721 A CN111206721 A CN 111206721A CN 201911156229 A CN201911156229 A CN 201911156229A CN 111206721 A CN111206721 A CN 111206721A
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- fastening element
- component
- adhesive
- memory alloy
- base body
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- 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
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
- E04C5/01—Reinforcing elements of metal, e.g. with non-structural coatings
- E04C5/02—Reinforcing elements of metal, e.g. with non-structural coatings of low bending resistance
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
- E04G21/12—Mounting of reinforcing inserts; Prestressing
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G23/00—Working measures on existing buildings
- E04G23/02—Repairing, e.g. filling cracks; Restoring; Altering; Enlarging
- E04G23/0218—Increasing or restoring the load-bearing capacity of building construction elements
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- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Connection Of Plates (AREA)
- Working Measures On Existing Buildindgs (AREA)
Abstract
In order to reinforce a component (6), the invention proposes a fastening element (1) having a base body (2) made of a pseudo-plastically-stretched profiled memory alloy and an adhesive (5) for adhering the base body (2) to the component (6). In order to introduce compressive stresses into the component (6), the fastening element (1) is fastened to the component (6), for example using an anchor (9), and heated to the transformation temperature of the shaped memory alloy, so that the base body (2) contracts and compressive stresses in the component (6) are generated, and the adhesive (5) bonds the base body (2) to the component (6).
Description
Technical Field
The invention relates to a fastening element for reinforcing components in the building industry having the features of the preamble of claim 1 and to a method for introducing compressive stresses into components having the features of the preamble of claim 9.
Background
International patent application WO 96/12588 a1 describes a method for retrofitting a bending beam, in which a plate made of a pseudoelastically stretched profiled memory alloy is used, which plate is bonded to the underside of the bending beam or to the side which is convexly curved as a result of the bending load of the bending beam, and is heated after the adhesive has cured to or above the transformation temperature of the profiled memory alloy. In the preassembled state, in which the plate is not yet arranged on the component, the adhesive is still separated from the plate. For assembly, adhesive is applied to the bending beam and bonds the panel to the bending beam. By the phase change of the shape memory alloy, the plate stuck at the bending beam contracts and thereby the curvature of the bending beam is reduced. Cracks that may be present on the convexly curved side of the bending beam are narrowed or closed in this case.
Disclosure of Invention
The object of the invention is to provide a fastening element for components made of concrete, for example, based on a shape memory alloy and a method for introducing compressive stresses into a component using the fastening element. The fastening element can be used for example in retrofitting for reinforcing components. By means of the fastening elements, it is possible to counteract, for example, bending of the components, or to bend or twist (i.e. twist) the components, or to pre-tighten the components in compressive stress in the manner of prestressed concrete.
This object is achieved according to the invention by a fastening element having the features of claim 1 and by a method according to claim 9.
The fastening element according to the invention having the features of claim 1 has a base body which is produced from a pseudo-plastically stretched form memory alloy.
A shape memory alloy is a metal alloy that changes its shape through a phase transformation of its crystalline structure between martensite and austenite. The phase change and shape change occurs when the transition temperature is reached or exceeded. The shaped memory alloy must be deformed pseudoplastically beforehand, which is typically, but not necessarily, achieved by mechanical deformation which can then be fully or partially recovered by heating to or above the transformation temperature. The shape memory alloy can be heated by introducing a certain material specific heat into the shape memory alloy, causing it to contract. The heat can be introduced in particular by means of a heating element, an infrared radiator or by means of an electric current flowing through the shaped memory alloy, via an ohmic resistance which leads to heating in the interior of the shaped memory alloy. Induction heating is also possible. From the typical temperature limits for the respective alloys, the shaped memory alloy thereafter seeks to assume its original, unstretched shape, which contracts (memory effect). In particular, shaped memory alloys composed of NiTi, NiTiCu, CuZn, CuZnAI, CuAINi, FeNiAl, FeMnSi or ZnAuCu have been proposed. The material composition is exemplary and not exhaustive. Shaped memory alloys with a two-way effect are also known, which change shape at high temperatures and recover fully or partially at low temperatures. Herein, "pseudo-plastically deformed forming memory alloy" is to be understood as a metal alloy or other alloy that changes its shape if it is heated to or above the transformation temperature, regardless of whether this occurs due to a change in its crystalline structure or otherwise, and also regardless of whether the forming memory alloy has been previously deformed, heated or cooled or otherwise processed.
For the purposes of the present invention, the pseudo-plastic deformation is stretching, and the formed memory alloy is pseudo-plastically stretched. By "pseudo-plastic stretching" it is meant that a matrix formed of the shaped memory alloy contracts and/or exerts a stretching force if it is prevented from contracting when it is heated to or above a temperature referred to herein as the "transformation temperature". Stretching the matrix is not necessary, however it is necessary: it contracts or exerts a stretching force if it is heated to or above a temperature known as the "transformation temperature".
In order to reinforce the component, a fastening element is arranged at the component, and at least the base body of the fastening element is heated to or above the transformation temperature of the shaped memory alloy. The component to be reinforced can be, for example, plate-shaped or rod-shaped and/or consist of concrete or reinforced concrete. For example, the component is a bridge which, as a result of the load being applied, bends higher than the planned setting and thus has cracks on its underside.
According to the invention, a curable adhesive is arranged on the base body for connecting the base body and the component in the preassembled state, in which the fastening element is not yet arranged on the component, but is provided, for example, after being transported to the construction site.
The base body is, for example, a plate or sheet made of a profiled memory alloy, on which a layer made of a heat-curable adhesive is arranged in a planar or punctiform manner on one or both sides for connecting the base body to the component. As used herein, an "adhesive" refers to a material that adhesively (i.e., by material bonding) bonds itself and the shape memory alloy to the component. "the adhesive is already arranged on the base body in the preassembled state" means: the adhesive is already arranged at the base body before the base body is arranged on the component. In particular, the adhesive is not activated in the preassembled state. By "activated" is meant herein that the adhesive is in a state in which it is capable of bonding the substrate to another object (e.g., a component). For example, adhesives in the form of hot melt adhesives are liquid or viscous in the activated state, while the adhesives are solid after cooling. In the solid state, however, the adhesive is no longer active for adhesion, but must be activated by heating for this purpose. Since the adhesive is not activated in the preassembled state, the fastening element according to the invention can be handled and transported in a simple manner.
The adhesive is in particular heat-activatable and/or heat-curable, that is to say the bonding of the component by means of the adhesive is effected by the introduction of thermal energy into the fastening element. The adhesive is referred to as "heat-activatable and/or heat-curable" because it is not activated at room temperature, but is activated (i.e. in particular viscous and deformable) only at a curing temperature of at least 50 ℃ and preferably 80 ℃ and preferably at least 100 ℃, so that it can connect two objects or start to cure by a chemical process which is triggered by an elevated temperature. The adhesive must first be heated to a higher temperature for curing and only then cured at this temperature or at a higher temperature and/or when subsequently cooled to an ambient temperature of, for example, about 20 ℃.
Another requirement of the binder is that it is stable at least until the transformation temperature of the shaped memory alloy is reached, which can be higher than the temperature required for activation or curing. This means that the adhesive does not decompose, for example, when it is heated to the transformation temperature of the shaped memory alloy, but the adhesive activates or cures in order to adhesively connect the substrate with the component when it is heated to the transformation temperature and possibly also to higher temperatures.
The transformation temperature of the shaped memory alloy is, for example, above 120 ℃, 150 ℃ or higher, and, in particular, about 200 ℃.
Preferably, the binder is solid at room temperature (which means its aggregate state) before and after curing, and/or is not or only slightly tacky.
For example, epoxy resins or synthetic resins are used as binders, which exhibit a reversible behavior as thermoplastics when heated for a short time to temperatures of 90 ℃ to 110 ℃ and which crosslink irreversibly and form-stably as thermosets when heated to higher temperatures of more than 110 ℃.
The adhesive is preferably arranged on at least one side of the base body in the preassembled state. Preferably, the substrate is coated with an adhesive at least in places in the preassembled state, the adhesive thus lying directly against the substrate. The adhesive can be arranged over the surface, in particular over a large part of at least one side, or only in spots or in places, also in a plurality of locations, which can be connected to one another or spaced apart from one another. In particular, the adhesive in particular completely wraps the substrate, i.e. from all sides, so that the adhesive surrounds the substrate essentially in a planar manner, so that, for example, external moisture cannot reach the substrate or can only reach the substrate at locally limited gaps or bores which, for example, can be provided for optional fastening elements (for example, anchors for end fastening). In this case, the adhesive forms a coating. In particular, the coating can additionally serve as corrosion protection for the substrate.
With a preferred embodiment of the fastening element according to the invention, the application of the substrate (i.e. the application of the adhesive for the preassembled state) is effected by heating the adhesive to a temperature below the transformation temperature of the shaped memory alloy of the substrate. By heating, the adhesive softens, becomes viscous or liquid, so that the adhesive at the base body can be permanently arranged as a coating and can be brought into the desired shape. The temperature required for this is also referred to below as the "deformation temperature". The heating for the coating is carried out in particular at deformation temperatures of up to 70 ℃ to 110 ℃. In particular, the binder is a thermoplastic material which is deformable into a thermoplastic, for example at a deformation temperature of 80 ℃ to 90 ℃, and which also retains its thermoplastic structure after cooling.
Furthermore, it is preferred that the binder is cured in the range of the transformation temperature of the shaped memory alloy, i.e. has a curing temperature which is in the range of the transformation temperature or below the range of the transformation temperature. The curing proceeds in particular irreversibly. For example, the adhesive can behave as a thermoplastic below the curing temperature, and cure by crosslinking after reaching the higher curing temperature (i.e., the temperature required for coating), resulting in a thermoset.
The adhesive can be applied to the substrate alone or directly. In a further preferred embodiment of the fastening element according to the invention, the fastening element is constructed as a composite material, in particular as a laminate material. By "composite material" is meant here a material which consists of two or more materials which are composite with one another. If the materials are layered layer by layer, they form a laminate. For example, the fastening element according to the invention has a plate made of a profiled memory alloy or a sheet made of a profiled memory alloy on which a layer of adhesive is arranged on one or both sides. Thus, the substrate and the adhesive form a laminate. It is also possible to combine the adhesive with the carrier material as a matrix on a board or panel. For example, fibrous materials are used as carrier materials. The fibrous material can have unidirectional, bidirectional or otherwise regularly arranged or unordered fibers, fabrics, knits, nonwovens, felts or other textile structures in the form of a sheet
One aspect of the present invention has a prepreg with a binder. "prepregs" are prefabricated, usually plate-shaped elements with curable synthetic resins, in particular epoxy resins, in which fibers are embedded as individual fibers or in the form of a textile structure in the form of a flat structure, for example made of glass, stone, carbon, plastic. For example, the prepreg is arranged on one side of the substrate, or on each side of the substrate. A single fiber or a textile structure made of fibers made of a shape memory alloy can also be arranged on one prepreg or between two prepregs.
The base body of the fastening element is preferably embodied in the form of a rod (e.g. round rod) or a plate (e.g. plate strip).
The method according to the invention having the features of claim 9 is provided for introducing compressive stresses into a component. The elements are for example made of concrete, also reinforced concrete, and/or are plate-like or rod-like. The method can be used for retrofitting or in a new state from the outset.
According to the invention, the fastening element in any of the preceding embodiments is connected to the component, to be precise without the aid of an adhesive for the fastening element. For the connection, the base body of the fastening element can be glued to the structural element and/or fastened to the component mechanically, for example using an anchor or by clamping. Other fastening means are also possible. The connection takes place at fastening points or fastening surfaces which are spaced apart from one another or also over the entire surface of the base body. In particular, the fastening element is connected to the component at its ends and, if necessary, also additionally between its ends. In particular, the anchor bolt penetrating into the component is arranged as an end fastener, i.e. at the end of the base body. The fastening points or fastening surfaces are spaced apart from one another in the pseudo-plastic elongation direction of the shaped memory alloy of the fastening element (i.e. in the direction in which the basic body has been pseudo-elastically stretched) so that by heating the shaped memory alloy to or above the transformation temperature, the shaped memory alloy exerts a tensile force on the component in the sense of reducing the spacing of the fastening points or fastening surfaces. The tensile force applied by the formed memory alloy causes a mechanical compressive stress in the component. The shape memory alloy of the fastening element according to the invention is capable of pseudo-plastic stretching in one or two dimensions and, correspondingly, shrinking in one or two dimensions if it is heated to or above the transformation temperature. Thereby, one-dimensional compressive stress or two-dimensional compressive stress can be introduced into the member. Preferably, the shaped memory alloy of the matrix is pseudo-plastically stretched in one dimension.
For example, the fastening element according to the invention is fastened at the stretch zone of the component. A tensile zone is a region in which tensile stresses occur in the component as a result of the loading of the component or the mechanical stresses of the component. For a member that is bent, the stretch zone is on the following side: the sides stretch due to the bending and bow convexly. In the case of horizontally arranged components, which are loaded vertically due to their own weight and possibly external weight, the stretching zone is below and the fastening element according to the invention is fastened at the underside. In the case of a component which is pulled in one dimension, the fastening element according to the invention can be fastened at the component on opposite sides, on a plurality of sides or on all sides.
After the fastening element is connected to the component, the fastening element is heated to or above the transformation temperature of the shaped memory alloy of the base body, so that the base body contracts and mechanical compressive stresses are introduced into the component.
By heating to or above the transformation temperature, the adhesive of the fastening element is cured, wherein curing can only be performed during cooling of the adhesive to ambient temperature. Upon curing, the adhesive of the fastening element connects the base of the fastening element with the component. One or more connections of the fastening element to the component, which have been established before heating to or above the transformation temperature, can remain present or be removed after the adhesive has cured.
In order to connect the fastening element according to the invention to the component before heating to or above the transformation temperature of the shape memory alloy, the invention provides that the fastening element is arranged at the component and is heated to the curing temperature of its adhesive, which is lower than the transformation temperature of the shape memory alloy. Thereby, the adhesive is cured and connects the substrate, which is made of a shaped memory alloy, with the component. The fastening element can be heated to the curing temperature as a whole and thereby be connected to the component in a completely planar manner. The fastening elements can also be heated to the curing temperature in limited sections and thereby be connected to the component at fastening faces spaced apart from one another, which correspond to the heated sections. After the adhesive has cured and after the resulting connection of the base body to the component, the fastening element is heated to the transformation temperature of the shaped memory alloy, so that the base body shrinks as a result of the phase transformation and/or tensile stresses are applied to the component, which cause compressive stresses in the component. The fastening element can be cooled between heating to the curing temperature of the adhesive and heating to the transformation temperature of the shaped memory alloy, or further heated to the transformation temperature after or without maintaining the curing temperature. The method is based on the premise that the adhesive, after curing, retains sufficient strength when heated to the transformation temperature of the shaped memory alloy so that the connection to the component is subjected to tensile forces of the substrate. It is therefore preferred that the adhesive irreversibly cures, as described above. If this is not the case, the fastening element must be connected to the component independently of its adhesive, as described above.
One aspect of the invention provides that a reinforcement and/or corrosion protection is applied to the base of the fastening element on the side facing away from the component. The reinforcement can be, for example, a fiber insert of a prepreg which is arranged on the side of the shape memory material facing away from the component and which is initially part of the composite material of the fastening element according to the invention, or which is applied afterwards. The adhesive of the fastening element according to the invention is also capable of simultaneously forming corrosion protection.
According to a further development of the method according to the invention, the fastening element is connected to the structural element by means of tensile stress, so that the fastening element already introduces compressive stress into the component without shrinkage of its base body. As the matrix shrinks when heated to or above the transformation temperature, the tensile stress of the fastening element and the compressive stress introduced into the component increase.
The features and feature combinations previously described in the description, of the invention and the embodiments and variants and features and feature combinations mentioned in the description of the figures and/or depicted in the figures can be used not only in the respectively illustrated or depicted combination, but also in principle in any other combination or alone. Embodiments of the invention are possible without all the features of the dependent claims. The individual features of the claims can also be replaced by other disclosed features or combinations of features. This embodiment of the invention is also possible, which does not have all the features of the examples.
Drawings
In the following, the invention is further elucidated with reference to the embodiments shown in the drawings. The figures show:
FIG. 1 is a fastening element according to the present invention; and
fig. 2 a beam with a fastening element according to the invention.
Detailed Description
The fastening element 1 according to the invention shown in fig. 1 serves to introduce mechanical tensile stresses into a component 6, which component 6 is made of concrete, for example. The fastening element 1 is a strip-shaped or plate-shaped or, in other words, a two-dimensional or planar component. The fastening element 1 is designed as a composite material, more precisely as a laminate, which in this exemplary embodiment has two layers, namely a sheet made of a pseudoplastically stretched, profiled memory alloy as a matrix 2 and a prepreg 3 with an adhesive 5, which is applied in a locked manner, i.e. by bonding, on one side of the matrix 2. More than two layers (not shown) are also possible. Alternatively, instead of the prepregs 3, only the adhesive 5 can be arranged at the matrix 2. The adhesive 5 is an epoxy resin, also referred to below as a synthetic resin, which can be applied as part of the prepreg 3 or alternatively can also be applied directly as a coating onto the substrate 2. For this purpose, the adhesive 5 is briefly heated to a deformation temperature of 90 ℃ to 110 ℃, so that the adhesive 5 and thus the prepreg 3 can be deformed and can be bonded to the substrate 2 in a planar manner.
The substrate 2 is made of a shaped memory alloy. A shape memory alloy is a metal alloy that changes its shape when the transformation temperature is reached or exceeded due to a phase change in its crystalline structure. For this purpose, the shape memory alloy must be deformed pseudoplastically beforehand. In this embodiment, the shaped memory alloy has been pseudo-plastically stretched such that: it contracts and/or, when its contraction is impeded, exerts a tensile stress if it is heated to or above the transition temperature.
The prepreg 3 is a strip-shaped or plate-shaped element with a synthetic resin as a binder 5, in which glass, carbon or other fibers 4 are embedded. Thus, the prepreg 3 is a fibre composite material forming a layer of the fastening element 1, which is a laminate (as mentioned). In this exemplary embodiment, the fibers 4 form a fabric, however, other planar textile structures (such as knits, nonwovens, felts or monofilaments) are also possible, which can be arranged, for example, unidirectionally, bidirectionally or randomly.
The synthetic resin of the prepreg 3 is bonded to the matrix 2 made of a pseudo-plastically stretched molding memory alloy, and can be cured by heating to a curing temperature, and thereafter bonded. The synthetic resin of the prepreg 3 is the adhesive 5 of the fastening element 1 according to the invention, which serves to adhesively bond the matrix 2 to a further component. The synthetic resin forming the binder 5 is irreversibly cured by means of a thermosetting plastic by crosslinking when the curing temperature is reached or exceeded. The synthetic resin is resistant to high temperatures at least up to the transformation temperature of the shaped memory alloy of the base body 2 and preferably up to higher temperatures, so that it does not decompose, when it is heated together with the base body 2 to or above the transformation temperature of the shaped memory alloy, but it solidifies when heated to the transformation temperature or at a lower solidification temperature or when subsequently cooled to, for example, ambient temperature and connects the base body 2 to the further component by adhesion in a cohesive manner.
As mentioned, the fastening element 1 according to the invention serves to introduce mechanical compressive stresses into the component 6. Fig. 2 shows, as an example, a plate 7 with a girder 8, which in this example can be made of reinforced concrete and can be, for example, a bridge. The member 6 bends downward due to its own weight and a load of, for example, a vehicle, not shown, wherein the bent portion is exaggeratedly shown.
According to the invention, the fastening element 1 is fastened to the underside of the member 6 (in this embodiment, at the bottom of the beam 8), wherein the elongation direction and the pulling direction of the fastening element 1 extend in the longitudinal direction of the member 6. At the lower side, the beam 8 is arched convexly downwards due to the bending and, thus, is under tensile stress at the lower part. The underside or the region adjoining the underside forms a so-called stretching zone in which there is a mechanical tensile stress.
In this embodiment, the fastening element 1 is mechanically connected with the anchor bolt 9, which is anchored in the beam 8 through the fastening element 1, with the beam 8 and thus also with the component 6. The anchor head of the anchor 9 is located below the sheet metal strip 10 transversely to the fastening element 1 in order to distribute the clamping force over a larger area. The fastening element 1 is connected to the beam 8 at or near its two ends and in this embodiment additionally at a plurality of further fastening points 11 between its two ends. The fastening points 11 are spaced apart from one another in the longitudinal direction of the fastening element 1 and thus in the direction of its pseudo-plastic stretching and in the direction of its pulling. The fastening points 11 can also be provided only at both ends of the fastening element 1.
After the fastening element 1 is connected to the beam 8 or the component 6 at the fastening point 11, the fastening element 1 is heated to the transformation temperature of the shape memory alloy or to a higher temperature, so that the base body 2 contracts and a compressive stress is generated in the tensile region of the beam 8, so that the bending of the component 6 is counteracted and the recovery from the bending is reduced or even completely. Furthermore, the synthetic resin of the prepreg 3, which forms the adhesive 5 of the fastening element 1 and connects the matrix 2 with the beam 8 and thus with the member 6, is cured. In principle, the sheet metal strip 10 and the anchor bolt 9 (i.e. the mechanical connection of the fastening element 1) can then be removed together with the beam 8, even if this is not provided.
The fastening element 1 can also be connected to the component 6 or the beam 8 with a tensile stress, wherein the tensile stress increases if the fastening element 1 or the base body 2 is heated to or above the transformation temperature of the shaped memory alloy. The compressive stress in the lead-in member 6 or the beam 8 increases accordingly.
In this embodiment, the transformation temperature of the shaped memory alloy of the base 2 of the fastening element 1 is about 200 ℃, and the fastening element 1 is heated to about 200 to 220 ℃. The curing temperature of the binder 5 of the prepreg 3 is in this embodiment between 120 ℃ and 180 ℃, and the synthetic resin can be heated more strongly for curing without decomposition or damage.
The prepreg 3 can be used for mechanical reinforcement and/or corrosion protection, and furthermore, further layers, for example further prepregs (not shown), can be applied on the fastening element 1. A corrosion protection layer and/or a reinforcement, in particular a second prepreg, can be applied from the outset to the other side of the matrix 2 made of a pseudoelastically stretched shape memory alloy, so that the matrix 2 is located between two prepregs 3, which are in particular in contact at the edges and are connected when heated (not shown).
In order to introduce compressive stresses, two or more fastening elements 1 according to the invention can be fastened on opposite sides or on all sides of a straight component, and by heating to the conversion temperature, compressive stresses (not shown) in the component can be generated. This is similar to prestressed concrete.
For connection with the beam 8 or, in general, with the component 6, the fastening element 1 can also be heated to the curing temperature of its adhesive 5 at the fastening point 11, so that the fastening element 1 is connected with the beam 8 or the component 6 at the fastening point 11, which is more appropriately referred to as "fastening face" in this case. Subsequently, the fastening elements 1 between the fastening points 11 are heated to or above the transformation temperature of their forming memory alloy, so that the base body 2 contracts and compressive stresses in the component 6 or the beam 8 are generated.
Another possibility is to first heat the fastening element 1 to the curing temperature of its adhesive 5, for example 150 ℃, in order to connect it with the component 6 or beam 8, and subsequently heat the fastening element 1 to a transformation temperature of about 200 ℃, so that the matrix 2 shrinks and compressive stresses in the component 6 or beam 8 are generated. The precondition for this is that the adhesive 5 cures irreversibly and retains sufficient strength when heated to the transformation temperature in order to withstand the tensile forces generated by the fastening element 1, so that the connection of the fastening element 1 to the component 6 or the beam 8 remains present and is not destroyed.
To cure the adhesive 5, the fastening element 1 can be cooled after heating to the curing temperature and thereafter heated to the transformation temperature.
List of reference numerals
1 fastening element
2 base body
3 prepreg
4 fiber
5 adhesive
6 component
7 plate
8 Beam
9 anchor bolt
10 strip of sheet material
11 fastening point
Claims (12)
1. Fastening element (1) for reinforcing a component (6) in the construction industry, wherein the fastening element (1) has a base body (2) made of a pseudo-plastically stretched profiled memory alloy, wherein the base body (2) is heated to or above a transformation temperature of the profiled memory alloy for reinforcing the component (6), characterized in that, in a preassembled state, in which the fastening element (1) is not yet arranged at the component (6), a curable adhesive (5) is arranged at the base body (2) for connecting the base body (2) and the component (6).
2. The fastening element according to claim 1, characterized in that the adhesive (5) is arranged on at least one side of the basic body (2) in the preassembled state or is wrapped with a memory material.
3. The fastening element according to claim 1 or 2, characterized in that the substrate (2) is coated at least in places with the adhesive (5) in the preassembled state, the adhesive forming a coating.
4. The fastening element according to claim 3, characterized in that said application is effected by heating said adhesive (5) to a temperature below said transformation temperature.
5. The fastening element according to any one of the preceding claims, characterized in that the adhesive (5) is cured, in particular irreversibly cured, in the range of the transformation temperature of the forming memory alloy.
6. The fastening element according to any of the preceding claims, characterized in that the fastening element (1) is constructed as a composite material, in particular a laminate material.
7. The fastening element according to any one or more of the preceding claims, characterized in that the fastening element (1) has a prepreg (3) with an adhesive (5).
8. The fastening element according to one or more of the preceding claims, characterized in that the base body (2) of the fastening element (1) is rod-shaped or planar.
9. Method for introducing compressive stresses into a component (6), wherein a fastening element (1) according to one or more of the preceding claims is connected with the component (6) in the preassembled state at fastening points (11) which are spaced apart from one another in the direction of elongation of the base body (2), and thereafter heating the fastening element (1) to or above the transformation temperature of the shape memory alloy, causing the base body (2) to contract and introducing the compressive stress into the component (6), characterized in that the adhesive (5) of the fastening element (1) is cured by heating the fastening element (1) to or above the transformation temperature of the shaped memory alloy of the substrate (2), the adhesive (5) connects the base body (2) of the fastening element (1) to the component (6) in a cohesive manner.
10. Method according to claim 9, characterized in that the fastening element (1) is heated to a curing temperature of the adhesive (5), which curing temperature is lower than the transformation temperature of the forming memory alloy of the substrate (2), and that the fastening element (1) is heated to or above the transformation temperature of the forming memory alloy of the substrate (2) after the curing of the adhesive (5) and after the resulting connection of the substrate (2) with the component (6).
11. Method according to claim 9 or 10, characterized in that a reinforcement and/or corrosion protection is applied on the side of the base body (2) of the fastening element (1) facing away from the component (6).
12. The method according to one or more of claims 9 to 11, characterized in that the fastening element (1) is connected with the component (6) with a tensile stress, such that the fastening element (1) introduces a compressive stress into the component (6) without shrinkage of the basic body (2), which compressive stress increases as a result of shrinkage of the basic body (2).
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102018129385.2 | 2018-11-22 | ||
| DE102018129385 | 2018-11-22 | ||
| DE102019128494.5 | 2019-10-22 | ||
| DE102019128494.5A DE102019128494A1 (en) | 2018-11-22 | 2019-10-22 | Clamping element for reinforcing a component in construction and method for introducing compressive stress into a component |
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| CN111206721A true CN111206721A (en) | 2020-05-29 |
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| CN201911156229.3A Pending CN111206721A (en) | 2018-11-22 | 2019-11-22 | Fastening element for reinforcing elements in the construction industry and method for introducing compressive stresses into an element |
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| DE (1) | DE102019128494A1 (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006046974A8 (en) * | 2004-06-04 | 2006-08-03 | Cornerstone Res Group Inc | Method of making and using shape memory polymer composite patches |
| CN102933387A (en) * | 2010-06-04 | 2013-02-13 | 波音公司 | Shape memory alloy/fiber reinforced polymeric composite structures and method for forming |
| CN105378129A (en) * | 2013-04-08 | 2016-03-02 | Re-Fer股份公司 | Method for producing prestressed concrete structures by means of profiles made of shape memory alloys and structure produced according to said method |
| CA2971244A1 (en) * | 2014-12-18 | 2016-06-23 | Re-Fer Ag | Method for producing prestressed structures and structural parts by means of sma tension elements, and structure and structural part equipped therewith |
| WO2016130326A1 (en) * | 2015-02-10 | 2016-08-18 | University Of Houston System | Self-stressing shape memory alloy-fiber reinforced polymer patch |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996012588A1 (en) | 1994-10-19 | 1996-05-02 | Dpd, Inc. | Shape-memory material repair system and method of use therefor |
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- 2019-10-22 DE DE102019128494.5A patent/DE102019128494A1/en not_active Withdrawn
- 2019-11-22 CN CN201911156229.3A patent/CN111206721A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006046974A8 (en) * | 2004-06-04 | 2006-08-03 | Cornerstone Res Group Inc | Method of making and using shape memory polymer composite patches |
| CN102933387A (en) * | 2010-06-04 | 2013-02-13 | 波音公司 | Shape memory alloy/fiber reinforced polymeric composite structures and method for forming |
| CN105378129A (en) * | 2013-04-08 | 2016-03-02 | Re-Fer股份公司 | Method for producing prestressed concrete structures by means of profiles made of shape memory alloys and structure produced according to said method |
| CA2971244A1 (en) * | 2014-12-18 | 2016-06-23 | Re-Fer Ag | Method for producing prestressed structures and structural parts by means of sma tension elements, and structure and structural part equipped therewith |
| WO2016130326A1 (en) * | 2015-02-10 | 2016-08-18 | University Of Houston System | Self-stressing shape memory alloy-fiber reinforced polymer patch |
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| DE102019128494A1 (en) | 2020-05-28 |
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