EP3601703A1

EP3601703A1 - Method, fastening element and fastening arrangement for attaching and activating shape memory alloy elements to structures to be reinforced

Info

Publication number: EP3601703A1
Application number: EP18711836.9A
Authority: EP
Inventors: Sebastian Horn
Original assignee: Fischerwerke GmbH and Co KG
Current assignee: Fischerwerke GmbH and Co KG
Priority date: 2017-03-22
Filing date: 2018-03-01
Publication date: 2020-02-05
Also published as: WO2018172032A1; DE102017106114A1

Abstract

The invention relates to a method, a fastening element and a fastening arrangement for fixing a shape memory alloy element (SMAE) (3) to a structure to be reinforced (3). One aim of the invention is to fasten the SMAE (3) robustly to the structure (2) to be reinforced and to subsequently activate same in the most simple way possible. To this end, according to the invention, the current that is needed to activate the SMAE (3) is to be introduced directly into at least one anchoring element (3) located on the SMAE and/or is to be introduced directly into a fastening element (7) located on the SMAE (3).

Description

description

Method, fastening element and fastening arrangement for attaching and activating shape memory alloy elements to be reinforced

buildings

The present invention relates to a method, a fastening element and a fastening arrangement for attaching and activating or electrical energy introduction of a shape memory alloy element (hereinafter referred to as FGLE) on a building having the features of the preamble of claims 1, 6 and 9.

This type of building reinforcement is to be regarded as a further development of the previously used building reinforcement, in which steel is poured into the concrete. The invention can be used both to buildings such as bridges, buildings o. Ä. preventively under pretension, as well as to reinforce subsequent cracks. Elements made of shape memory alloys, also known as shape memory alloys (SMA), are pre-stretched to a certain length and then attached to the structure. By introducing a certain amount of heat, the FGLE strive to pull themselves together to their original length before stretching, thus applying stresses of up to several hundred MPa to the structure.

Such a building reinforcement is disclosed in the document CH707301 B1. Here, profiles of shape memory alloys are mounted on a previously roughened outer surface of the structure. Subsequently, the profiles are poured into cement and completely poured over with cement. The applied cement layer acts in conjunction with the profiles as a reinforcing layer, because by the introduction of thermal energy in the profiles, these contract and thus the cement layer is compressed, which causes a reinforcing effect on the same because of the cohesive connection with the building. A major disadvantage of this known structure reinforcement is that the profiles are no longer accessible after pouring and not or only with considerable effort be dismantled from the building. In the case of retrofitting of, for example, bridge sections, overhead mounting is usually unavoidable, which is difficult to achieve by the use of cement. In general, the use of cement is accompanied by a cement-dependent curing time. Therefore, an energy input into the profiles and thus an efficient reinforcement of the structure can take place only after a certain time. The electrical contacts in the form of electric cables for energy input into the profiles must be cast together with the profiles. Once encapsulated, the electrical contacts to the profiles are sealed, and in case of contact loss, only breaking out of the concrete inserts disclosed in the invention to provide access to the profiles or complete removal of the cement topcoat will help. In addition, in an accidental tearing or shearing off the electrical cable at or just above the cement topping an energy input into the profiles is no longer readily possible and consequently breaking out of the deposits or at least partial removal of the cement layer is inevitable here. In general, if the electrical connection between the profile and the electric cable fails, the cement topcoat must be damaged.

The object of the invention is first to propose a method, whereby it is possible to mount in a simple manner necessary for the reinforcement of the structure FGLE on the building. In addition, it is an object of the invention to propose a method which allows a simple introduction of electric current into the FGLE for activation. Furthermore, it is an object of the invention to propose a special fastening element and a special fastening arrangement, by which the methods are realized.

The objects are achieved by the features of the method of claim 1, by the features of the fastener of claim 6, as well as by the features of the fastening arrangement of claim 9. The invention proposes at least one, in particular iron-based FGLE for reinforcing a structure consisting in particular of concrete or reinforced concrete. Furthermore, FGLEs of NiTi, NiTiCu, CuZn, CuZnAI CuAINi, FeNiAl, FeMnSi or ZnAuCu are proposed. The material composition is exemplary and not exhaustive. It is clear to the person skilled in the art that an FGLE can also consist of a composite material which possibly offers better mechanical properties than a pure alloy. The structure to be reinforced need not consist of concrete or reinforced concrete, it could also be natural or man-made stones or similar materials used in building, masonry or bridge construction. The size and geometry of the FGLE must be adapted to the structure to be reinforced. In particular, however, the FGLE is rod-shaped, strip-shaped or designed as a band with a particularly rectangular or square cross-section. Even a building belting geometry is possible. Before mounting the FGLE, it is slightly stretched below a temperature threshold characteristic of the respective alloy, at which phase transformation occurs within the structure, such that the property of the FGLE or the "memory effect" of the material is not lost This means, in particular, that the material must not be overstretched, such pre-stretching can be carried out directly at the factory after production, and pre-stretching with special devices directly on the construction site is envisaged, followed by attachment of the pre-stretched FGLE to the structure to be reinforced at least two points, in particular in the vicinity of the ends of the FGLE, by at least partially electrically conductive fastening elements and at least one anchoring element fixed at least partially in a borehole in the structure, in particular a threaded rod which has been cemented in. Also other heavy-duty elements known from the prior art Anchoring systems can be used as an anchoring element, for example mortared composite anchors, spreading bolt or sleeve anchors and undercut anchors. The FGLE is anchored over the anchoring element and fasteners such that an electric current can be introduced into the FGLE. This can be realized, for example, by at least two mutually separate fastening elements arranged on the FGLE, such that a current activating the FGLE flows from a fastening element via the FGLE into at least one second fastening element. The current flow can also be realized between at least two anchoring elements arranged on the FGLE or between at least one fastening element and at least one anchoring element. In particular, there is an electrically conductive connection between the FGLE and the anchoring element and / or the FGLE and the fastening elements. According to the invention, an "electrically conductive connection" is understood to mean an electrical conductivity which is customary for metallic conductors.The invention provides that the current which leads to a current flow within the FGLE and thus serves to activate the FGLE, in at least one of the fastening elements and / or. or introduced into at least one of the anchoring elements. "Introduced" here means that a contacting of a power source directly to the respective anchoring element or directly on the relevant fastener and not indirectly, for example, via the FGLE. Due to the electrically conductive connection between the FGLE, the anchoring element and the fastening elements, the most favorable position for power supply can be selected for mounting or activation. A current activating the FGLE leads to Joule heating in the FGLE. From a temperature limit typical for the respective alloy, the FGLE strive to assume their original unstretched shape (memory effect). In this case, a tensile stress is transferred from the FGLE via the fastening elements and the anchoring elements to the structure to be reinforced. If a certain weight force, which is dependent on the material used of the FGLE, is then applied perpendicularly to the tension or tension direction of the FGLE, as is the case, for example, in the case of bridge reinforcements in the form of heavy-duty transporters, the FGLE together with the bridge will gradually become "hammock-like" If this is the case, by reactivating the FGLE again, the FGLE can be restored to its original, unbent and shorter shape, thus again reinforcing the bridge against bending, especially in bridge construction, for example, with a large number of individual shorter ones Instead of using a few large FGLEs, the maximum number of pre-strain and activation cycles is significantly dependent on the magnitude of the pre-strain of the FGLE.

An embodiment of the invention provides that the fastening elements of the FGLE and / or of the anchoring element used are solvable. Additionally or alternatively, the FGLE after removal of the fasteners of the structure to be reinforced can be solved. The embodiment of the invention opens up the possibility of relatively easy to install the FGLE at another position to be reinforced, as well as the FGLE, as well as the fasteners to dismantle completely from the structure to be reinforced. The advantage lies in the reusability of the FGLE and the fasteners, as they are exposed only to possible weather conditions, but not coated with, for example, cement or other cover layers. In order to protect the fastening arrangement from the effects of weathering, this can be covered, for example, by means of a corresponding, weatherproof device. Also, a sealing of the fastening arrangement is conceivable. In order to ensure optimum stress transfer of the FGLE to the structure to be reinforced, an embodiment of the invention provides that a material-locking connection, in particular an adhesive connection, is produced between the FGLE and the building to be reinforced. This cohesive connection can also be used to pre-fix the FGLE in order to simplify the actual anchoring by the fastening elements, in particular in an overhead installation.

In order to be able to use a current source which is to be used to activate the FGLE, for example for a plurality of FGLE arranged on a structure, an embodiment of the invention provides that the current source can be detached from the fastening element and / or the anchoring element, that is to say in particular not is fixed by a permanently fixed, for example, soldered or otherwise permanently fixed cable or similar connection. An embodiment of the invention provides that the detachable connection between the power source used in the fastening element and / or the anchoring element current source is in particular a screw, plug, clamp or clip connection. These include luster terminal and crocodile-type connections, as well as magnetic snap connections. Due to the large number of usable types of connection, the most suitable type of connection for the particular installation or configuration of the system FGLE anchoring fastening elements can be selected. In addition, in case of unintentional loosening or tearing off, for example, a screw connection, current can be fed in quickly and simply by means of, for example, a crocodile clamping connection for activation. A possible standardization of the connection type is also possible.

An inventive fastening element for application of the method according to the invention consists of an at least one side surface-structured element, an adapter element and a coatable on the anchoring element in the building fixture. Optionally, an additional washer can be used. All the fastener comprehensive parts consist of an at least partially electrically conductive material. Electrically conductive means in this case also for metallic conductors typical electrical conductivity values. The surface-structured element, in particular a sheet, may have different shapes, in particular the sheet has the shape of a rectangle, a square, a circular disk, a trapezoid or another, polygonal shape. The Surface is roughened at least on one side by a mechanical or chemical process and thus includes grooves, grooves or other type of structure which increases roughness. The adapter element may have a truncated cone, a truncated pyramid, any polygon or similar, three-dimensional geometry. The explanations are exemplary and not exhaustive. The height of the adapter element corresponds to a multiple of the thickness of the surface-structured element, that is in particular significantly higher than the thickness of the surface-structured element. On the anchoring element, in particular a threaded rod, a clamping device, in particular a threaded nut can be applied, through which a force along the anchoring element can be acted upon. The adapter element has on one side a passage opening whose diameter corresponds at least to the diameter of the anchoring element. In addition, the adapter element has a projection on a passage opening which is so pronounced that it can correspond with a through hole located in the surface-structured element, in particular a fit, primarily such that a clearance fit can be formed.

An embodiment of the adapter element according to the invention provides that at least one side, in particular a side which adjoins the extension and / or points in the direction of the surface-structured element, has a roughened structure, similar to the surface-structured element, which serves to reduce the friction between FGLE and increase the surface-structured element.

In order to achieve the best possible force gradient for the introduction of the stress forces by the FGLE in the structure to be reinforced, and at the same time to minimize the shear forces on the anchoring element, an inventive design of the fastener sees a cohesive connection, in particular an epoxy resin compound, between the anchoring element and the through hole of the adapter element.

A fastening arrangement according to the invention with a fastening element for the application of the method according to the invention is designed as follows: The surface-structured element is arranged with at least one surface-structured side, which faces away from the surface of the structure to be reinforced, anchoring element anchored in the structure. An FGLE is attached to the anchoring element anchored in the structure and to the surface-structured one Element arranged such that the structured side of the surface-structured element with the FGLE comes into contact and thereby the static friction between the FGLE and the surface-structured element is increased. The adapter element is arranged on the anchoring element anchored in the structure in such a way that it engages with its extension in the shape memory element as well as in the surface-structured element in such a way that the surface-structured side of the adapter element located on the extension is directed in the direction of the FGLE and thus increasing the friction between the adapter element and the FGLE. Between the surface-structured element, the FGLE and the adapter element there is thus in particular a form-fitting connection which serves to ensure optimum introduction of force into the structure to be reinforced and at the same time to reduce the shear forces acting on the fastening element per se. In order to reinforce the absorbable forces by the purely positive connection between the surface-structured element, the FGLE and the adapter element and to ensure adequate anchoring of the FGLE on the structure to be reinforced, a fastening arrangement according to the invention provides for the use of a tensioning device which is located on the structure Anchoring element is arranged. This clamping device, which is in particular a threaded nut, exerts a force along the anchoring element in the direction of the structure to be reinforced. In particular, the tensioning device exerts a force acting in the direction of the structure to be reinforced on the adapter element, the FGLE and the surface-structured element. As a result, the surface-structured surface of the adapter element and the surface-structured surface of the surface-structured element is pressed or at least pressed in the FGLE, whereby a frictional and / or positive connection is formed, which additionally ensures that upon activation of the FGLE and the associated power transmission FGLE firmly anchored to the fastener remains. Between the adapter element and the tensioning device, a washer can be attached to protect the adapter element. But this is not absolutely necessary. In addition, the clamping device does not necessarily have to be a threaded nut. Also, a set screw containing adjusting ring can be used in conjunction with a depression in the anchoring element to brace the fastener against the structure to be reinforced. In order to be able to activate a FGLE, a flow of current between at least two fastening elements and / or two anchoring elements must be realized by current introduction into at least one of the fastening elements and / or in at least one of the anchoring elements. For this purpose, the fastening arrangement according to the invention provides that an electrically conductive connection exists between the anchoring elements, the respective fastening element arranged thereon and the associated FGLE to be activated. In addition, connections are provided on the fastening elements and / or on the anchoring elements, which correspond with corresponding terminals of the current source used for power supply. One possible location for such a connection is an outer surface of the adapter or fixture. Also, for example, the washer between clamping device and adapter or a connection on the anchoring element itself can be used as a connection surface. The invention will be explained in more detail with reference to an embodiment shown in the drawing.

1 shows an inventive mounting arrangement in the installed state in a perspective view and a symbolically illustrated power source with an exemplary and an imaginary connection to the mounting arrangement. Figure 2 is a perspective section through the mounting arrangement of

Figure 1 along the shape memory alloy element and along the fastener.

Figure 3 is an exploded perspective view of the invention

Fastening arrangement with hidden underground and shortened threaded rod.

In the figures 1 and 2, an embodiment of a fastening arrangement 1 according to the invention is shown. The fastening arrangement 1 comprises a building 2 to be reinforced, a shape-memory alloy element (FGLE) 3 reinforcing the building 2, two fastening elements 7, wherein in the Figures 1 and 2 each only one fastener 7 is shown, an anchoring element 30, which is shown in this embodiment of the invention as a threaded rod 6, a current source 25 and an epoxy resin 27 between the FGLE 3 and the structure to be reinforced 2. Figure 3 shows in In Figures 1 and 2 is a section of the structure to be reinforced 2, for example, a precaution or after a resulting structural defect reinforced bridge girder or a similar cantilevered Construction shown. The possible use of the reinforcement is versatile and so can generally be a variety of structures, thin-walled constructions, prefabricated components, such as concrete pipes or reinforced concrete columns, reinforced. In the cutouts shown in Figures 1 and 2, the threaded rod 6 is partially anchored in a blind hole 5, such that a part of the threaded rod 6 protrudes from the blind hole 5 and thus over the surface of the structure to be reinforced 2. The threaded rod 6 is anchored by means of a hardenable mass 26 in a gap 23 which is formed between the threaded rod 6 and the surface of the blind hole 5 located in the structure 2. The fastening element 7 consisting of an electrically conductive metal for fastening the FGLE 3 to the structure 2 to be reinforced comprises a tensioning device 31, in the exemplary embodiment designed as a threaded nut 16, a washer 15, an adapter element 8 and a surface-structured element 32, in the exemplary embodiment as a surface-structured metal sheet 12 educated. The geometry of the FGLE 3 must be adapted to the structure 2 to be reinforced. In the present embodiment, the FGLE 3 has the shape of a flat, rectangular sheet. Notwithstanding this may also be present a stiffener or cuboid shape. The FGLE 3 has at its two ends a through hole 4, which is slightly larger in diameter than the diameter of the threaded rod 6. In the embodiment, the through hole 4 shown is circular. Also a deviating geometric shape, such as a triangular shape, square shape or any other polygonal shape is possible. The surface-structured sheet metal 12, which consists in particular of an electrically conductive metal, serves to increase the friction between the structure 2 to be reinforced and the FGLE 3. It has a flat, quadrangular shape in the embodiment. However, the function is also given in a deviating geometric design. Therefore, the surface-structured sheet 12 may also be in the form of a washer or a have any other polygonal geometry. The surface-structured sheet metal 12 has a side 14 with a structured surface. By "structured surface" is meant, in particular, that the side 14 has a significantly higher roughness than that of the remaining sides. In particular, "structured" does not necessarily mean a regular structure. A regular structure may or may not exist. The structuring can be done mechanically, for example by grinding, sanding, sandblasting, milling or the like. It is also possible to achieve structuring by chemical or wet-chemical processes, such as etching. The surface-structured sheet metal 12 has at least one side 14 with a structured surface. Furthermore, the surface-structured metal sheet 12 has a through hole 13, which is slightly larger in diameter than the diameter of the threaded rod 6 but in particular corresponds to the diameter and the shape of the through hole 4. The adapter element 8 comprises a passage opening 9, a structured surface 10, and an extension 11 and consists of an at least partially electrically conductive material, in particular of an electrically conductive metal and has a block-like shape. In the exemplary embodiment, the adapter element 8 has a trapezoidal cross-section. Deviating from this embodiment, the adapter element 8 may also have another geometric shape, such as a cuboid, a rectangle, a hemisphere a truncated pyramid or another, fulfilling the technical function geometry. The passage opening 9 has a diameter which corresponds at least to the diameter of the threaded rod 6. The shape of the passage opening 9 is in particular cylindrical, but a deviation from this shape is possible, for example, any polygonal. By "the structured surface comprising the adapter element 8" is to be understood that the roughness on the structured surface 10 is significantly greater than on the remaining surface of the adapter element 8. In particular, structured surface does not mean that the structured surface 10 on the adapter element 8 is a regular one The patterned surface 10 may be fabricated by any mechanical or chemical process, as well as the patterned side 14 of the surface-structured sheet metal 12. The projection 11 is disposed on the structured surface 10 of the adapter element 8, including and extending it Through opening in the adapter element 8 and is designed in shape and diameter such that it can engage in the through hole 4 of the FGLE 3 and in the through hole 13 of the surface-structured plate 12. In particular, the extension 1 1 forms together with the through hole 4 in F GLE 3 and the Through hole 13 in the surface-structured sheet 12 a passungsähnliche connection. The extension 1 1 is formed in the example according to the invention as a circular disc. The depth of the extension 1 1 is limited in particular by the sum of the thicknesses of the FGLE 3 and the surface-structured sheet 1 1. The term "depth of the extension" 11 is to be understood as meaning the extent in the direction of the longitudinal axis of the through opening 9. The washer 15 consists of an electrically conductive metal and corresponds in particular to the diameter of the threaded rod 6. In the example according to the invention, the tensioning device is in the form of the threaded nut In contrast to this, other geometries are possible, such as square, polygonal or any form-chamfered or form-turned molds The black shaded areas in FIG. 1 mark possible connection points 18 to 22 on the threaded rod 6 or on the fastening element 7 are arranged for a used for activating the FGLE 3 power source 25. The connection points may be, for example, recordings for "banana plug". The banana plugs corresponding to the receptacles would thus be arranged on the cables which lead to the current source. This special type of electrical plug connection is only an example. In general, a variety of detachable connections can be selected. This includes, for example, clamping, screwing and clamping connections. All that is required for each type of connection is that it can stably transfer a certain amount of current dependent on the material of the FGLE 3 into the FGLE 3. FIG. 1 shows by way of example an electrically conductive connection 33 between the current source 25 and the terminal 22 located in the threaded rod 6. The connection 33 is not limited to the connection point 22 but can be connected to all possible connection points 18 to 22. The dotted line 34 symbolizes a connection between the power source 25 and located at the other, not shown end of the FGLE 3 threaded rod 6 or fastener 7. The connection is a closed circuit between the two threaded rods 6, respectively the two fasteners 7 and the intervening FGLE 3 realized. The current source 25 used for current injection into the FGLE 3 must be designed so that it is easy to transport and can transfer sufficient current into the FGLE 3 to cause a sufficiently high Joule heating in the FGLE 3 to effect a phase transformation. The temperature at which phase transformation occurs is significantly dependent on the material of the FGLE 3. In FIGS. 1 and 2 and in particular in FIG. 3, a special fastening arrangement 1 according to the invention of the FGLE 3 is shown on the structure 2 to be reinforced with the aid of the fastening element 7. On the in the structure 2, by means of a hardenable mass 26 in the intermediate space 23 between the threaded rod 6 and blind hole 5, anchored threaded rod 6, the surface-structured sheet 12 is arranged such that the structured side 14 of the surface-structured sheet 12 facing away from the surface of the structure to be reinforced 2 is. The threaded rod 6 engages in the through hole 4 on the FGLE 3 such that the FGLE 3 is arranged on the threaded rod 6 and on the surface-structured sheet 12. Between the building 2 and the FGLE 3 exists an epoxy resin layer 27, which forms an adhesive bond 29. The adapter element 8 is arranged and oriented such that the threaded rod 6 engages in the passage opening 9 of the adapter element 8 and the structured surface 10 of the adapter element 8 comes into contact with the FGLE 3. In addition, the extension 1 1 engages the adapter element 8 in the through hole 4 of the FGLE 3 and in the through hole 13 of the surface-structured sheet 12 a. A gap 24 between the threaded rod 6 and the through hole 9 in the adapter element 8 has a cohesive connection, in particular an epoxy resin 28 on. The washer 15 is arranged on the threaded rod 6 and on an extension 1 1 opposite side of the adapter element 8. The threaded nut 16 as a tensioning device is arranged on the threaded rod 6 so that it comes into contact with a surface of the washer 15.

In the following, the method according to the invention for attaching the FGLE 3 to the building 2 to be reinforced is presented and in the course of which the technical mode of action of the elements involved in the method is explained. The process requires a pre-stretched or activated FGLE 3. The pre-stretching / activation of the FGLE 3 is not part of the method according to the invention and described below, but will be briefly discussed for the sake of completeness and for a better understanding. First, the FGLE 3 to be installed is pre-stretched by a certain length depending on the material composition of the FGLE 3, which leads to a change in the metal structure within the FGLE 3. This is generally referred to as the activation of the shape memory alloy element. Pre-stretching of the FGLE 3 takes place along the longitudinal axis of the FGLE 3. A pre-stretched FGLE 3 can be delivered directly to the place of use, or pre-expanded on site with the help of special equipment. In order to anchor the FGLE 3 to the structure 2, For example, the FGLE 3 to be anchored must have at least two through-holes 4, which are arranged in particular at the ends of the FGLE 3. These can be prefabricated. However, it is also possible to manufacture the through-holes 4 at the site using a suitable drilling tool. Since the position and the number of blind holes 5 in the building 2 to be reinforced correspond in particular to the position and the number of through holes 4 in the FGLE 3, it is obvious that for the manufacture of the blind holes 3 the FGLE 3 with the through holes 4 located therein is considered to be one Type of stencil to use. For this purpose, the FGLE 3 would be prefixed to the structure 2 by means of, for example, an epoxy resin layer 27 or another fixing device. Subsequently, a suitable drilling device is guided through the arranged in FGLE 3 through holes 4 and then drilled directly into the structure 2. Subsequently, the prefixing is released again and the FGLE 3 removed from the structure 2. An advantage of this method lies in the good agreement of the distances of the through holes 4 and the blind holes 5. In addition, the respective through hole 4 can be used as a guide for the drilling device in the manufacture of the blind holes 5. The drilling dust resulting from the drilling is removed from the blind holes 5. The threaded rods 6 are anchored in the blind holes 5 by means of a curable mass 26, as is generally known for chemical fasteners, in the intermediate space 23 between the threaded rod 6 and blind hole 5. Subsequently, a surface-structured metal sheet 12, corresponding to the previously described fastening arrangement 1, is arranged on the threaded rods 6. The FGLE 3 is arranged by means of the through holes 4 on the threaded rods 6 and on the respective, located on the threaded rods 6, surface-structured sheet 12. Between the building 2 and the FGLE 3, an epoxy resin layer 27 is applied beforehand, which ensures a cohesive connection, in particular an adhesive bond 29 between the building 2 and the FGLE 3, which supports the transmission of the FGLE 3 into the building 2. As described in the fastening arrangement 1 described above, each threaded rod 6 is arranged in each case the adapter element 8, the washer 15 and the threaded nut 16 as a tensioning device. The washer 15 prevents direct contact of adapter element 8 and threaded nut 16. This prevents any damage to the adapter element 8 when tightening the threaded nut 16. A gap 24 between the threaded rod 6 and the passage opening 9 of the adapter element 8 is filled with an epoxy resin 28 cohesively. This connection also serves to support the transmission of FGLE 3 in the Structure 2. In addition, it reduces the lateral forces generated in the direction of the longitudinal extension of the FGLE 3 that the FGLE 3 exerts on the threaded rods 6. By tightening the threaded nut 16 with a certain torque along the threaded rod 6 in the direction of the structure 2, the threaded nut 16 exerts a force on the adapter element 8 in the direction of the structure 2. The positive connection, consisting of the extension 1 1, the through hole 4 and the through hole 13 is thereby secured against relative movement of the elements of the fastener 7 transverse to the longitudinal axis of the threaded rod 6. In addition, the structured surface 10 on the adapter element 8 and the structured side 14 of the surface-structured metal sheet 12 at least partially presses into the FGLE 3, whereby the non-positive connection between the surface-structured metal sheet 12, the FGLE 3 and the adapter element 8 is exerted by the threaded nut 16 becomes. After this step, the prestressed FGLE 3 is anchored to the structure 2 to be reinforced. Subsequently, a current source 25 is connected to the possible connection points 18 to 22 between at least two fastening elements 7 and a predefined current, which causes a predefined Joule heating in the FGLE 3, fed. As a result, the FGLE 3 strives to return to its original, unstretched length by phase transformation of the material, resulting in stressing of the structure 2 between the fasteners 7 disposed on the threaded rods 6. Finally, the current source 25 can be separated from the possible connection points 18 to 22. If the FGLE 3 is brought out of shape by mechanical load in the longitudinal direction, as is the case for example with bridge reinforcement by repeated high load, the power source 25 can be reconnected and thus the voltage on the structure 2, so the structure reinforcement per se, to be renewed.

LIST OF REFERENCE NUMBERS

buildings

1 mounting arrangement

building

Shape memory alloy element (FGLE)

Through hole in FGLE 3

blind

threaded rod

fastener

adapter element

Through opening in the adapter element 8

10 Structured surface on the adapter element 8

1 1 extension

12 Surface-structured sheet metal

13 through hole in the surface-structured sheet 12th

14 Structured side of the surface-structured sheet metal 12

15 washer

16 threaded nut

18-22 Possible locations for mounting electrical connections

3 space between the threaded rod 6 and blind hole. 5

4 gap between threaded rod 6 and through hole 9 in the adapter element 8 5 power source to activate the FGLE 3rd

6 Hardenable mass

7 epoxy resin layer

8 epoxy resin compound

9 adhesive bond

0 anchoring element

1 tensioning device

2 Surface-structured element Electrical connection between power source 25 and connection point 22 in threaded rod 6

Symbolically illustrated electrical connection between the power source 25 and a second, not shown fastening element 7 or anchoring element 30th

Claims

claims

Method for fixing a shape memory alloy element (FGLE) (3) to a building (2) to be reinforced, in particular made of concrete, and for introducing energy into the FGLE (3), characterized in that the FGLE (3) is formed at least partially by means of at least partially electrically conductive fastening elements (7) to the structure to be reinforced (2), in particular by an at least partially in a blind hole (5) in the building (2) arranged anchoring element (30) is attached, and for heat energy input into the FGLE (3) Current flow between at least two fastening elements (7) and / or two anchoring elements (30) is generated such that a FGLE (3) activating current flows through the FGLE (3), wherein the current flowing current in at least one of the fastening elements (7 ) and / or in at least one of the anchoring elements (30) is initiated.

A method according to claim 1, characterized in that the

Fixing elements (7) of the FGLE (3) and / or of the anchoring element (30) and / or the FGLE (3) of the structure to be reinforced (2) are detachable.

Method according to one of the preceding claims, characterized in that between the FGLE (3) and the structure to be reinforced (2) a cohesive connection, in particular an adhesive connection (29), is produced.

Method according to Claim 1, characterized in that a current source (25) used to introduce current into the fastening element (7) and / or the anchoring element (30) can be detached from the fastening element (7) and / or the anchoring element (30).

A method according to claim 4, characterized in that a connection between the power source (25) and the fastening element (7) and / or a Connection between the power source (25) and the anchoring element (30) for current introduction into the fastening element (7) and / or the anchoring element (30) is designed as a detachable connection, in particular as a screw, plug-in, clamping or clip connection.

6. Fastening element (7) for use in the method according to one of the preceding claims, characterized in that the fastening element (7) of a surface-structured at least one side element (32), in particular a surface-structured sheet metal (12), an adapter element (8) and a, on the anchoring element (30) in the building (2) can be applied tensioning device (31), in particular a threaded nut (16), is formed and that the adapter element (8) at least one through hole (9) whose diameter at least the diameter of the anchoring element (30) and on at least one side of the passage opening has an extension (1 1) which corresponds to a in the surface-structured element (32) located through hole (13), in particular forms a fit.

7. Fastening element (7) according to claim 6, characterized in that at least one of the surface-structured element (32) facing surface of the adapter element (8) has a textured surface (10).

8. Fastening element (7) according to claim 6 or 7, characterized in that in a gap (24) between the anchoring element (30) and the adapter element (8) a cohesive connection (28) can be produced.

9. fastening arrangement (1) with a fastening element (7) according to one of claims 6 to 8, characterized in that a FGLE (3) between, on the structure to be reinforced (2) arranged, surface-structured element (32) and the Adapter element (8) is fixed by force and / or positive connection, and in particular that the adapter element (8) has an extension (1 1) which corresponds to a recess (4) of the FGLE (3) and engages in this.

10. fastening arrangement (1) with a fastening element (7) according to claim 9, characterized in that a clamping device (31), in particular a Threaded nut (16), a contact force in the axial direction along the anchoring element (30), in particular a threaded rod (6), on the surface-structured element (12), in particular a surface-structured sheet metal (12), the adapter element (8) and arranged therebetween FGLE (3) exercises. Mounting arrangement (1) with a fastening element (7) according to claim 9 or 10, characterized in that between the fastening element (7), the FGLE (3) and the anchoring element (30) an electrically conductive connection exists and that the fastening element (7) and / or the anchoring element (30) has a connection for establishing a connection to a power source (25) for introducing energy.