WO2020104290A1

WO2020104290A1 - Method for prestressing a structure with a tensioning device, and use of such a tensioning device for fastening to a structure

Info

Publication number: WO2020104290A1
Application number: PCT/EP2019/081342
Authority: WO
Inventors: Juline KÄMMERER; Felix WEYAND; Sabine FISCHER-WILL
Original assignee: Thyssenkrupp Steel Europe Ag; Thyssenkrupp Ag
Priority date: 2018-11-23
Filing date: 2019-11-14
Publication date: 2020-05-28
Also published as: DE102018129640A1

Abstract

The invention relates to a method (100) for prestressing a supporting element (10) of a structure (1), comprising the following steps: providing (110) a tensioning device (20) having a tensioning axis (LS), wherein the tensioning device (20) comprises or consists of a shape memory alloy which has a one-way effect, wherein the tensioning device (20) extends along the tensioning axis (LS) in a starting state with a starting extent between a first and a second fastening portion (20a, 20b), and fixing (120) the tensioning device (20) in the starting state at least by the first fastening portion (20a) to the first receiving portion (10a) of the supporting element (10) and by the second fastening portion (20b) to the second receiving portion (10b) of the supporting element (10). Here, the tensioning device (20) has an austenite phase in the starting state.

Description

Method for prestressing a building with a tensioning device and use of such a tensioning device for fastening to a building

The invention relates to a method for prestressing a supporting element of a building, comprising the step of: providing a tensioning device with a tensioning axis, the tensioning device comprising or consisting of a shape memory alloy.

The invention further relates to the use of a tensioning device for permanent attachment to a structure for carrying a load and for applying a tension to secure the structure.

Shape memory alloys are alloys that can exist in two different crystal structures. After a previous plastic deformation, these alloys can be brought into their old form (programmed form) by exceeding the austenite start temperature, or A _s temperature for short, which is called the one-way effect. There are also alloys that remember their shape at two different temperatures. These then have a so-called two-way effect. In addition, shape memory alloys can exhibit pseudo-elastic behavior, which is characterized by a reversible stress-induced martensitic transformation. The term shape memory alloy is also known under the term shape memory material.

The thermal, chemical and mechanical behavior is largely determined by the alloy composition and the microstructure.

Clamping devices serve to reinforce buildings, prevent and prevent cracking. Furthermore, the lifespan of buildings can be extended by means of a tensioning device. Buildings or individual segments or elements of buildings are usually prestressed with a tensioning device. In particular, such a tensioning device is already being used today, for example, to reinforce against the bending of concrete parts or to tie up supports, for example, to increase the axial load and to increase the thrust. For this purpose, the structure must be prestressed with tendons in a bond or without bond with the respective structure. WO 2014/166003 A2 and CN 107407100 A each disclose a method for creating prestressed concrete components in new designs. Furthermore, these relate to a procedure to subsequently reinforce existing structures. In WO 2014/166003 A2, pre-stressed profiles made of shape memory alloys are connected to the building by means of cement-bound mortar. Further improvements are desirable.

Buildings with tendons are often prestressed in a composite. However, once the bond has been established, the preload can no longer be adjusted or adjusted depending on the load. Then, at most, structural elements together with the tendons prestressed in the composite can be removed and replaced by similar elements, for example bridge sections. By prestressing tendons without a bond, the prestress can be adjusted retrospectively, depending on the structure, but this is associated with a high level of resources and high costs.

It is therefore an object of the present invention to provide a method for prestressing structures and the use of a tensioning device which reduce or eliminate one or more of the disadvantages mentioned and / or are improved over existing solutions. In particular, it is an object of the present invention to provide a method for prestressing structures and the use of a tensioning device which enables simplified prestressing with less resource expenditure, in particular with less manpower, time and machine use. Furthermore, it is in particular an object of the present invention to provide a method for prestressing structures and the use of a tensioning device, which enable inexpensive prestressing of the structures.

This object is achieved with a method comprising the steps: providing a tensioning device with a tensioning axis, the tensioning device comprising or consisting of a shape memory alloy which has a one-way effect, the tensioning device being along the tensioning axis in an initial state with an initial extension between one extends first and a second fastening portion, and fixing the tensioning device in the initial state at least with the first fastening portion on the first receiving portion of the support element and the second fastening portion on the second receiving portion of the supporting element, wherein the tensioning device has an austenite phase in the initial state. The invention is based on the finding that load-bearing elements of a building sag more and more over time due to the load, that is to say they are deformed. The knowledge is based, for example, on the behavior of motor vehicle bridges, which usually sag with increasing operating time. This problem is also known, for example, from shelves or buildings.

The tensioning device extends along the tension axis with a longitudinal extent between the first and the second fastening section. The tensioning device preferably comprises a tensioning element which extends between the first and the second fastening section. Such a tensioning device can comprise or consist of a tensioning strand or a tensioning rope as tensioning element. In particular, the tensioning device can have one or more wires. Furthermore, it is conceivable that the clamping device is rod-shaped or rod-shaped. The tensioning element can furthermore in particular be flat, preferably in the form of a band or sheet. Continuous products, such as strips, sheets, coils, wires and the like, are particularly suitable as semifinished products for the clamping device.

The longitudinal extent of the tensioning device is generally many times greater than a width and height or thickness of the tensioning device extending perpendicular to the tensioning axis. Furthermore, the longitudinal extent is in particular many times greater than a radial extent extending radially to the clamping axis and a circumferential extent of the clamping device extending tangentially to the clamping axis.

The clamping device has a cross section perpendicular to the clamping axis. The cross section can have any shape, preferably circular, oval, square or the like. In particular, the cross section of the tensioning device can be, for example, I-shaped, T-shaped, H-shaped, U-shaped or the like. The cross section along the clamping axis is preferably constant. Alternatively, the cross section of the clamping device can vary, at least in sections, along the clamping axis.

In the installed state or in the operating state, the tensioning device preferably transmits a force essentially along the tension axis. A force can also act on the clamping device at an angle to the clamping axis. Additionally or alternatively, the tensioning device can also transmit a moment, in particular a bending moment or a torsional moment. As a rule, the clamping axis is a straight line, ie it has essentially no curvature. As an alternative, the clamping axis can run at least in sections in the form of an arc, in particular with one on the Clamping device acting at an angle to the load on the load axis, the load axis arched. The clamping device is preferably arranged coaxially with the clamping axis.

The clamping device comprises the shape memory alloy at least in sections along the clamping axis. The tensioning device preferably comprises a section with a shape memory alloy with a constant longitudinal extent over the width and / or the height of the tensioning device. Furthermore, the clamping device comprises a section with a shape memory alloy with a constant longitudinal extension over the radial or circumferential extension of the clamping device. In particular, the longitudinal extent of the shape memory alloy encompassed by the tensioning device is essentially constant over the cross section. Alternatively, the clamping device can have a varying longitudinal extension of the shape memory alloy across the clamping axis, over the width and / or the height or over the circumferential extent or the radial extent. The longitudinal extension of the shape memory alloy preferably increases or decreases over the width or height or radial extension of the clamping device perpendicular to the clamping axis.

Any suitable shape memory alloy, preferably iron-based, which has a one-way effect, can be used as the shape memory alloy. Preferred shape memory alloys are, for example, NiTi-based, Cu-based or Fe-based alloys.

Provision of the tensioning device preferably means that the tensioning device is ready to be fixed on the support element for the installed state or operating state. A provided clamping device is preferably available for fixing to the support element. Providing includes in particular that the tensioning device is provided at the installation position or the operating position. The tensioning device is particularly preferably available for mounting on the support element.

It is to be understood that the tensioning device has an austenite phase for provision in the initial state. In particular, it should be understood that the tensioning device is advantageously not provided in a pre-stretched state in the initial state. The tensioning device or the shape memory alloy is particularly preferably not provided in a plastically cold-formed manner.

The first and second fastening sections are designed to fix the tensioning device to the first and second receiving sections of the support element. The support element preferably extends along a support axis with a longitudinal extension between the first and the second receiving section. Fixing can also mean connecting, picking up or fastening. The first and second receiving section of the support element thus take up the tensioning device, in particular the first and second fastening section, and transmit the load acting on the support element and the associated deformation of the support element to the tensioning device. In a suitable manner, the deformation preferably leads to an advance of the tensioning device, in particular the shape memory alloy. Furthermore, the tensioning device can also transmit a force to the support element. The fixing method step is preferably carried out by a non-positive connection, in particular by a screw connection. Furthermore, the fixing method step can preferably be carried out by means of a positive connection. In particular, the fixing method step can be implemented by a material connection, for example by an adhesive connection or welded connection. In a preferred manner, the fixing method step can be implemented by a combination of the non-positive, positive and / or material connection.

In particular, the first and second fastening sections and the first and second receiving sections are designed for fixing with a screw connection and / or a positive connection. The tensioning device is preferably detachably fixed to the support element, for example by means of a screw connection and / or clamp connection. Alternatively or additionally, the first and second fastening section of the tensioning device can be integrally connected to the first and second receiving section of the support element. The first and second fastening sections particularly preferably have a fastening surface with a preferred roughness. In addition, the first and second receiving sections preferably have a receiving surface with a preferred roughness. The roughness (Ra value) is preferably in a range from 1 pm to 10 pm, more preferably 2 pm to 8 pm, 2 pm to 7 pm, 2 pm to 5 pm, particularly preferably 4 pm to 5 pm. The fastening surfaces are designed for fastening to the first and second receiving sections. The receiving surfaces are designed to fix the first and second fastening sections to the first and second receiving sections.

The tensioning device can also be an integral part of the support element or form the support element. In a particularly suitable manner, the first and second fastening sections are each designed as a fastening element. The respective fastening element and the tensioning element are preferably suitable for being non-positively connected to one another, in particular by means of a clamp connection. In particular, the tensioning device comprises or consists of the tensioning element and two fastening elements. It is conceivable to implement the clamp connection by means of a screw connection. As an alternative or in addition, a positive connection between the tensioning element and the fastening element is also conceivable, for example by means of a nose or a hook, which can be in engagement with a corresponding groove. Additionally or alternatively, a material connection, in particular a welded connection or adhesive connection, is also conceivable.

Advantageously, the deformation of the support element resulting from the dead weight of the support element or from the load acting on the support element can be used to stretch the shape memory alloy. In particular, the manufacturing step of plastic cold forming, for example by cold rolling, can be omitted. The arrangement according to the invention saves the pre-stretching production step in an advantageous manner even during manufacture. The use of time, resources and personnel is particularly preferred. The method according to the invention for assembling a non-pre-stretched clamping device makes it possible, in particular, to provide and assemble semi-finished products which are inexpensive and which have a shape memory alloy.

It is further preferred that the method for prestressing comprises the steps: deforming the tensioning device with respect to the initial extension by a relative transformation deformation depending on the load and converting the

Shape memory alloy of the jig from the austenite phase in

Initial state in a martensite phase of a deformation state with a deformation extension along the span axis.

A force acts on the tensioning device via the support element. The tensioning device is deformed as a function of a load acting on the support element. For this purpose, the load acting on the support element leads to a force which acts on the tensioning device. The force acting on the tensioning device from the support element is therefore dependent on the load. The load can act selectively or as a surface load on the support element. In general, the load will act on the support element substantially perpendicular to the support axis. It is also conceivable that a load remains essentially acts parallel to the support axis on the support element. It is to be understood that the load can act in particular asymmetrically on the support element. In particular, the load can be monotonically increasing and / or monotonically decreasing as a surface load. Alternatively and / or in addition, a constant surface load can also act on the support element.

It is understood that the load can comprise a static and a dynamic load component. The static and dynamic load share can overlap. The static load component results, for example, from the dead weight of the supporting element or the structure and other stationary units. The static load component is essentially constant. The dynamic load depends, for example, on the weather, that is to say on winds, and / or on road traffic, for example vehicles or people. In particular, the dynamic load component can have a superposition of different dynamic load profiles, for example of vehicles and the wind. In particular, different frequencies and / or amplitudes can characterize the dynamic load profiles. Individual dynamic load profiles can be periodic. It is to be understood that the load and thus the force can vary over time.

Depending on the load size, load changes, load direction and specific structural design of the support element or the structure, the support element deforms vertically and / or along the support axis. The arrangement of the first and second receiving sections and the arrangement of the first and second fastening sections fixed thereon change accordingly. This leads to a corresponding deformation of the clamping device perpendicular and / or along the clamping axis.

The load on the support element preferably acts essentially as a tensile force on the tensioning device. In addition and / or alternatively, the load can also act on the tensioning device as a moment, in particular as a bending moment and / or torsional moment. In particular, it is conceivable that the load acts additionally or alternatively as a compressive force on the tensioning device. In particular, it should be understood that the force acting on the tensioning device can alternate between the tensile force and the compressive force. Furthermore, the direction of action of the bending moment and / or the torsional moment can also change. The changes essentially depend on the dynamic load component or the individual dynamic load profiles.

The shape memory alloy changes depending on a relative transformation deformation measured along the span axis from the austenite phase to the deformation state with the martensite phase. The is particularly preferably Martensite phase in the deformation state as e-martensite in a hexagonal crystal lattice structure. Furthermore, the martensite phase can have hexagonal crystal lattice structures of the e-martensite and cubic body-centered crystal lattice structures of the ά-martensite.

The relative transformation deformation is the load-related change in length of the clamping device in relation to the initial extent. In particular, the relative transformation deformation relates to a deformation essentially parallel and / or coaxial to the clamping axis. The relative transformation deformation is also referred to as strain e. It is understood that the relative transformation deformation includes pseudoplastic deformation of the martensite. The relative transformation deformation of the tensioning device during the deformation is preferably greater than an elastic and pseudo-elastic expansion of the shape memory alloy. It is important when deforming that plastic deformation actually takes place, so that the elastic and pseudo-elastic expansion is exceeded.

To prevent the material from being destroyed, the relative transformation deformation is preferably below the total elongation at break A. In particular, the relative transformation deformation of the tensioning device is less than the uniform expansion A _g . This avoids overloading the material. The relative transformation deformation of the tensioning device during deformation is preferably less than A, and / or A _g , measured in accordance with DIN EN ISO 6892-1, as of 2017-02. Preferably the relative transformation strain is at least about 6% A _g and / or at most about 65% A _g . The relative transformation deformation is preferably in a range of 17-25% A _g . Preferred values for the relative transformation deformation of the tensioning device during deformation are preferably in a range from 1 to 10%, preferably 2 to 8%, 3 to 7%, 4 to 6%, preferably approximately 5%. Other ranges can also be preferred, for example 2 to 5%, or 5 to 9%, depending on which shape memory alloy is used.

The relative transformation deformation of the tensioning device during the deformation is preferably set in such a way that a maximum restoring stress and / or maximum restoring movement based on the shape memory alloy is obtained. Depending on the purpose for which the tensioning device is used, either a maximum reset voltage or a maximum reset movement is preferred. An optimum of both can also be found if this is preferred for the respective application. The relative transformation deformation is in the context of Shape memory alloys used in this disclosure preferably in about 5%, or is in the above-mentioned areas.

The shape memory alloy is particularly preferably an iron shape memory alloy and is provided in an austenite phase. In a preferred variant, the iron shape memory alloy is an FeMnSi system. These are particularly suitable as shape memory alloys and have shown that they have good recovery properties. In addition and / or as an alternative to the Fe-based alloys, the shape memory alloy preferably comprises a Cu-based and / or NiTi-based alloy. Cu-based alloys are, for example, CuZn, CuZnAI, Cu13.95AI3.93Ni (weight percent), CuAIMn. CuAIBeMn, CuAIMnV. NiTi-based alloys are, for example, Ti16Zr10Nb4Ta (atomic percent), NiTi, NiMnlnMg, PtTi.

Depending on the relative transformation deformation, the shape memory alloy of the clamping device changes from the initial state with the austenite phase to the martensite phase of the deformation state. The conversion from the austenite phase to the martensite phase is thus particularly induced by the application of a force caused by the load and thus mechanical stress. The induced mechanical stress is preferably less than the yield strength of the shape memory alloy in the austenite phase. The transformation from the austenite phase to the martensite phase is essentially diffusion-free, especially due to heavy movements.

In particular, the shape memory alloy converts in a temperature interval from the austenite phase to the martensite phase, at which the temperature lies above the martensite finish temperature M _f and below the martensite deformation temperature M _d . The martensite finishing temperature M _f and the martensite deformation temperature M _d essentially depend on the type of shape memory alloy.

Advantageously, the deformation of the support element resulting from the dead weight of the support element or from the load acting on the support element can be used to stretch the shape memory alloy. In particular, the assembly step of plastic cold forming, for example by cold rolling, can be omitted. The arrangement according to the invention advantageously saves one process step in production and thus saves time, resources and personnel. The method according to the invention for the assembly of a non-stretched tensioning device enables to provide and assemble, in particular, inexpensive manufactured semi-finished products that have a shape memory alloy.

A preferred embodiment of the method comprises the steps: relieving the tensioning device of the load, preferably by at least about 30% of the load, heating the shape memory alloy of the tensioning device to a phase transition temperature, converting the shape memory alloy of the tensioning device from the martensite phase in the deformation state to an austenite phase with a memory state a memory extension, and pretensioning of the support element as a function of a reset voltage of the shape memory alloy of the tensioning device induced by the memory extension.

In order to convert the shape memory alloy from the deformation state with the martensite phase to the memory state with the austenite phase, the tensioning device must be relieved. As a rule, the support element with the tensioning device attached to it is relieved. In particular, the support element is relieved in such a way that the tensioning device is relieved by at least 10% of the load and / or more. The load is particularly preferably reduced by 30% and / or more to relieve the tensioning device. In particular, the load is reduced by 50% and / or more to relieve the tensioning device.

Relieving takes place, for example, by means of support devices which counteract the load acting on the support element and thus the load on the tensioning device. In particular, the support device can be a support element or a lifting device. In addition and / or alternatively, the load for the method for prestressing the tensioning device can be reduced. The static load component is preferably reduced, for example by reducing the dead weight. Furthermore, the dynamic load component and the associated load peaks can be reduced. In particular, vehicle and / or passenger traffic can be set for bridges, for example.

To convert the shape memory alloy into its original crystal structure, the austenite, the clamping device or the shape memory alloy is to be heated to a phase transition temperature. For this purpose, the phase transition temperature of the shape memory alloy is preferably heated above the austenite start temperature (A _s temperature) and below an austenite finish temperature (A _F temperature). The As temperature of the shape memory alloy is preferably in a temperature interval from -200 ° C. to + 400 ° C. In a particularly preferred manner, the As temperature for NiTi-based or Cu-based shape memory alloys lies in a temperature range from -200 ° C to + 200 ° C. The A _s temperature of Fe-based shape memory alloys is preferably in a temperature range from -200 ° C to + 150 ° C or from + 25 ° C to + 400 ° C. For some shape memory alloys, such as described in WO 2014/146733 A1 or application PCT / EP 2017/063322 by the present applicant, the respective contents of which are fully incorporated by reference, the A _s temperature is preferably in a temperature interval of 30 ° C up to 135 ° C.

The A _f temperature of the shape memory alloy is preferably in a temperature interval between 100 ° C. and 400 ° C., for example for Fe shape memory alloys, or between 200 ° C. and 375 ° C., for example for shape memory alloys such as in WO 2014/146733 A1 or Application PCT / EP 2017/063322 described.

By relieving and heating the tensioning device, the shape memory alloy of the tensioning device can change from the martensite phase to the austenite phase of the memory state. Due to the phase change, the tensioning device is in the memory state with a memory extension. To pretension the support element with the tensioning device, the support element must be loaded accordingly again with the load. The load reduction brought about by the relief is particularly preferred. In particular, the support device which may be arranged for the relief is to be removed. In particular, the load customary for the installed state or operating state must be restored. For bridges, for example, this can include the opening of road traffic.

The prestressing essentially results from a reshaping of the tensioning device. The reshaping essentially depends on the memory extension. In particular, the recovery is the difference between the memory extension and the deformation extension. A restoring voltage is particularly preferably induced as a function of the reshaping. In particular, a restoring force acts on the supporting element as a function of the restoring voltage. Depending on the reset voltage, the tensioning device prestresses the support element. The tensioning device has for tensioning the support element preferably a relative recovery between 1.5% to 4%, preferably 2%. In the case of the relative recovery, the recovery is preferably related to the extent of the deformation or else to the extent of the memory. The reset voltage is preferably between 300MPa and 600MPa.

In this preferred embodiment, the advantages already introduced can be realized in a particularly suitable manner.

In the memory state, the tensioning device is preferably designed as a pressure element, provided that the memory extension is greater than the deformation extension. The tensioning device is particularly preferably designed as a tension element, provided the memory extension is smaller than the deformation extension.

Furthermore, an embodiment of the method is preferred in which the support element extends in a main direction of extension essentially along a support axis and the tensioning device with the tension axis is arranged essentially parallel to the support axis and at a distance.

The distance between the clamping device and the supporting element is preferably the distance orthogonal to the supporting axis and the clamping axis. The support element preferably has a thickness or height perpendicular to the support axis and the tensioning device has a thickness or height perpendicular to the tension axis. The tensioning device is preferably spaced parallel to the support element such that the distance between the tension axis and the support axis results from the sum of half the thickness of the support element and half the thickness of the tensioning device. Alternatively, the clamping axis and the supporting axis can be arranged essentially coaxially with one another. In this preferred embodiment, the distance between the supporting axis and the clamping axis is essentially zero. In particular, the support element in this embodiment preferably forms the tensioning device. It is also conceivable that the tensioning axis and the support axis are arranged at a different distance from one another. The clamping axis and the supporting axis are preferably arranged with the minimum possible distance from one another.

As an alternative to this, it is preferred that the support element extends in a main direction of extension essentially along a support axis and the tensioning device with the tension axis is arranged essentially transversely to the support axis of the support element. The supporting axis is preferably in the neutral fiber. The neutral fiber of the support element describes that fiber or layer, the length of which is constant regardless of a load (transverse to the support axis), that is, the length always corresponds to the initial extension. The supporting axis is preferably in the neutral fiber. The support axis lies in particular in the case of such support elements in the neutral fiber, which are supported by means of a fixed-lot bearing or lot-lot bearing, preferably symmetrically.

Furthermore, the support element is preferably substantially loaded with a load transverse to the support axis. As an alternative or in addition, it is conceivable that the support element is essentially loaded with a load parallel to the support axis.

A further embodiment of the method preferably comprises the steps: providing a tensioning device designed as a pressure element, providing a tensioning device designed as a tension element, fixing the tensioning device designed as a pressure element in the memory state on a side of the support element that is subjected to pressure in the installed state of the support element, and fixing the memory element in the memory state designed as a tension element on a tensioned side of the support element in the installed state of the support element.

In particular, a supporting element that is loaded transversely to the supporting axis comprises a tensioning device on a side that is pressure-loaded in the installed state or operating state in the longitudinal direction of the supporting axis, and a tensioning device on a side that is tension-loaded in the installed state or operating state from the pressure-loaded side in the longitudinal direction of the supporting axis further tensioning device, which can be designed as a tension element.

With this preferred embodiment, in addition to the advantages already introduced, prestressing can be carried out in particular on supporting elements that are subjected to bending.

In particular, the shape memory alloy of the clamping device is a shape memory alloy, consisting of an alloy with the following alloy components in percent by weight:

25.0% <Mn <32.0%,

3.0% <Si <8.0%,

3.0% <Cr <10.0%,

0.1% <Ni <4.0%, PS 0.1%,

SS 0.1%,

Mo <0.5%,

Cu <0.5%,

- AI S 5.0%,

Mg <5.0%,

OS 0.1%,

Ca <0.1%,

Co <0.5%, at least one element from a group 1 of elements being present, the group 1 consisting of the elements N, C, B with the following contents

N <0.1%,

CS 0.1%,

B <0.1% and the following applies to the sum of the group 1 alloy components:

and at least one element from a group 2 of elements is present, group 2 from the elements Ti, Nb, W, V, Zr with the following contents

Tis 1.5%,

Nb <1.5%,

- WS 1.5%,

VS 1.5%,

Zr <1.5% and the following applies to the sum of the group 2 alloy components: Ti, Nb, W, V, Zr> 0.1

Group 2 and for the ratio of the sum of the alloy components of group 1 and group 2, each in atomic%: 0.5 2.0

with the rest iron and unavoidable impurities.

Such an alloy is described in WO 2014/146733 A1 by the present applicant, the disclosure content of which is fully incorporated herein by reference. It has been found that this material is particularly suitable for prestressing devices for prestressing structural elements. The excretions influencing the shape memory effect, the formation of which is influenced by the ratio of the two element groups, group 1 and group 2, show a clear, positive influence on the shape memory effect, provided that the sum of the components of the elements of group 2 in at% of the alloy in relation to the sum of the alloy components of group 1 in at% lies in the range from 0.5 to 0.2. This sets a targeted stoichiometric ratio of the elements of group 1 to the elements of group 2. It was found that precisely with this ratio of the alloy components of group 2 to group 1, the formation of precipitates is particularly favorable and supports the shape memory effect. If the specified ratio is less than 0.5, for example, the excretion elements in the form of N, C and / or B cannot be set and the shape memory effect is reduced since the elements of group 1 are present in the structure in dissolved form.

Alternatively, the shape memory alloy consists of the following

Alloy components in percent by weight:

25% - 30% Mn,

4% - 8% Si,

3% - 7% Cr,

0.5% - 1% V,

0.1% - 0.5% C, and balance iron and unavoidable impurities.

Such an alloy is described in the (not yet published) application PCT / EP 2017/063322 by the present applicant, the content of which is fully incorporated herein by reference. Such a shape memory alloy has one improved reset voltage compared to the prior art. For the alloy system, this is preferably at least 500 MPa, preferably at least 600 MPa. It has been found that this alloy has an almost constant restoring stress at a pre-stretch of 1 to 10%. Furthermore, it has an excellent reversibility of the phase change. The elements of vanadium and carbon are preferably present in the shape memory alloy in the form of vanadium carbide nanoparticles. VC nanoparticles have a small difference in atomic radii, so that they fit very well in face-centered cubic lattices. The VC nanoparticles in the shape memory alloy preferably occupy a volume in the range from 0.1 to 3% by volume. In this way, the formation of stacking errors can be optimized. VC nanoparticles preferably have a size in the range from 2 to 50 nm, more preferably 10 to 50 nm. The phase transition temperatures of this shape memory alloy TMS and TAS are preferably in the range from 0 ° C. to 450 ° C., more preferably in the range from 120 ° C to 370 ° C. For further details, in particular the manufacturing process of this alloy, please refer to PCT / EP 2017/063322.

In a second aspect of the invention, the above-mentioned object is achieved by using a tensioning device for permanent attachment to a structure for carrying a load and for applying tension to secure the structure, the tensioning device comprising or consisting of a shape memory alloy has a one-way effect, and extends in an initial state with an initial extension between a first and a second fastening section along a clamping axis, the shape memory alloy of the clamping device having an austenite phase in the initial state, and wherein the clamping device is not pre-stretched in the initial state.

A first preferred embodiment of the use of the tensioning device is characterized in that the tensioning device extends along the tensioning axis in a deformation state with a deformation extent between the first and the second fastening section, and wherein the tensioning device extends relative to the initial extent by a relative transformation deformation deformed under a load and the shape memory alloy of the tensioning device changes from the austenite phase in the initial state to a martensite phase in the deformation state.

According to a second preferred embodiment of the use of the tensioning device, the tensioning device extends along the tensioning axis in one Memory state with a memory extension between the first and the second fastening section, the shape memory alloy of the tensioning device has an austenite phase in the memory state, and the tensioning device, which is relieved by at least about 30% and heated to a phase transition temperature, changes from the martensite phase in the deformation state to the austenite phase of the memory state um, and prestresses the building in the state of memory.

In particular, the use of the tensioning device is suitable for structures such as a bridge, a building, a vehicle, a high-bay warehouse, a pipeline, a girder, a rod structure or a machine.

The use according to the invention of a tensioning device for permanent fastening to a structure for carrying a load and for applying tension to secure the structure and its preferred further developments have features which make it particularly suitable for or with a method according to the invention for prestressing a supporting element of a building and its respective training courses.

Regarding the advantages, design variants and design details of these further aspects of the invention and its developments, reference is also made to the preceding description of the corresponding features of the method for prestressing a supporting element of a building or the respective other aspects.

Embodiments of the invention will now be described below with reference to the drawings. These are not necessarily to show the embodiments to scale, rather the drawings, if this is useful for the explanation, are carried out in a schematic and / or slightly distorted form. With regard to additions to the teachings which can be seen directly from the drawings, reference is made to the relevant prior art. It should be taken into account here that various modifications and changes regarding the form and the detail of an embodiment can be made without departing from the general idea of the invention. The features of the invention disclosed in the description, in the drawings and in the claims can be essential for the development of the invention both individually and in any combination. In addition, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or the detail of the ones shown and below described preferred embodiments or limited to an object that would be limited compared to the object claimed in the claims. For the specified design ranges, values within the stated limits should also be disclosed as limit values and can be used and claimed as required. For the sake of simplicity, the same reference numerals are used below for identical or similar parts or parts with an identical or similar function.

Further advantages, features and details of the invention emerge from the following description of the preferred embodiments and from the drawings; 1a-c show a schematic representation of a structure as a bridge, vehicle and building with a tensioning device attached to it;

Fig. 2 is a schematic flow diagram of a first preferred

Method for prestressing a support element;

FIGS. 3-6 are schematic representations of exemplary embodiments of a tensioning device provided and fixed on a support element;

Fig. 7 is a schematic flow diagram of a second preferred

Method for prestressing a support element;

Fig. 8 is a schematic flow diagram of a third preferred

Method for prestressing a support element; and Fig. 9 is a schematic flow diagram of a fourth preferred

Method for prestressing a support element.

FIGS. 1a-c show a schematic representation of a building 1 as a bridge, vehicle and building with a tensioning device 20 attached thereto. The embodiments shown in FIGS. 1a-c show in particular a preferred selection of possible uses of a tensioning device 20 for permanent attachment to a building 1.

FIG. 2 shows a first preferred sequence of a method for prestressing 100 a supporting element 10 of a building 1 with a tensioning device 20. This preferred The embodiment includes providing 1 10 such a clamping device 20, which has a shape memory alloy, and fixing 120 the clamping device 20 to the support element 10.

In particular, the clamping device 20 is provided in an initial state in which the shape memory alloy is not pre-stretched. The shape memory alloy is particularly preferably not cold-rolled in the initial state. In the initial state, the shape memory alloy of the clamping device 20 is preferably essentially in an austenite phase. In the initial state, the clamping device 20 extends from a first fastening section 20a to a second fastening section 20b along a clamping axis LS. The tensioning device preferably has an Fe-Mn-Si shape memory alloy. Further preferably, the clamping device can have a shape memory alloy described in the patent specification EP 2 141 251 B1, the content of which is fully incorporated herein by reference. It should also be understood that the tensioning device 20 is also provided for fixing 120 to the support element 10 in the initial state.

For fixing 120, the tensioning device 20 is fastened via the first and second fastening section 20a, 20b to a first and second receiving section 10a, 10b of the support element. The tensioning device 20 can be integrally and / or non-positively and / or positively connected to the support element 10. FIGS. 3 to 6 show a selection of preferred possible embodiments of a provided 110 and a 120 tensioning device 20 fixed to a support element 10 of a building 1.

FIG. 3a shows a tensioning device 20 comprising a tensioning element which extends between a first and a second fastening element 20a, 20b. The clamping axis LS of the clamping device 20 and the supporting axis LT of the supporting element 10 are spaced apart in parallel. FIG. 3a essentially shows the longitudinal extent of the support element 10 along the support axis LT and the longitudinal extent of the tensioning device 20 along the tension axis LS. Furthermore, FIG. 3a shows with the extension of the support element 10 perpendicular to the support axis LT and with the extension of the tensioning device 20 perpendicular to the tension axis LS the thickness or height of the support element 10 and the tensioning device 20. FIG. 3b shows a schematic view of the tensioning device 20 and the support element 10 perpendicular to the view shown in FIG. 3a along the section AA. In the preferred example, the support element 10 extends substantially perpendicular to its thickness or height and longitudinal extent over a width that is greater than the extent of the tensioning device 20 over a width perpendicular to its thickness or height and longitudinal extent.

The tensioning element shown in FIGS. 3a and 3b is provided as a tensioning strand with individual wires. The tensioning cord is fastened to the respective end sections in a first and second fastening element 20a, 20b designed as an anchor. In particular, the respective end sections of the tension wire are braced in the anchor. The anchors are in turn attached to the first and second receiving sections 10a, 10b of the support element 10 in a preferred manner in a form-fitting and material-locking manner. The support element 10 has a groove-like depression in the region of the first and second receiving sections 10a, 10b, in which the first and second fastening elements 20a, 20b are embedded or received transversely to the support axis LT. In the direction of the support axis LT, the support element 10 forms the positive connection with the first and second fastening elements 20a, 20b. In addition, the present preferred exemplary embodiment has a welded connection between the first and second fastening elements 20a, 20b and the first and second receiving sections 10a, 10b.

FIGS. 4a and 4b show a further preferred example of a tensioning device 20 fixed to a support element 10. In particular, the tensioning axis LS and the support axis LT are spaced apart from one another by the distance D. The support element 10 and the tensioning device 20 extend in the direction of the support axis LT or the tensioning axis LS with a longitudinal extent. In a preferred manner, the tensioning device 20 lies essentially completely on the support element 10. The distance D between the clamping axis LS and the supporting axis LT preferably corresponds to half the height or thickness of the supporting element 10 and half the height or thickness of the clamping device 20.

Figure 4b shows the support element 10 over its longitudinal extent and perpendicular to it across its width in a plan view.

FIG. 4c shows a schematic sectional illustration of the clamping device 20 fixed to the support element 10 in the region of the first receiving section 10a and the first Fastening surface 20a along the section AA. FIG. 4c shows in particular an end view of the tensioning device 20 and the support element 10 over their height or thickness and their respective width.

In the preferred embodiment shown in FIGS. 4a and 4b, the clamping device 20 is provided with a rod-shaped or band-shaped clamping element. It is to be understood that the tensioning device is essentially fixed to the support element 10 only via the first and second fastening sections 20a, 20b. In the present preferred embodiment, the clamping device 20 has the first and second fastening sections 20a, 20b as a clamp connection. In particular, the clamping connection comprises a screw connection and a clamping element. To fix the tensioning element to the support element 10, the tensioning element between the first and second receiving sections 10a, 10b of the support element 10 and a clamping element is non-positively braced with the screw connection. For this purpose, both the first and second receiving sections 10a, 10b and the clamping element have corresponding bores. In the present preferred embodiment, the clamping connection for each fastening section 20a, 20b is provided with four screws. It is conceivable to vary the size or the strength and / or the number of screws, in particular with higher loads. The clamping device 20 can then be fixed to the support element 10 by means of the screws guided through the bores. It is additionally preferred to design the first and second fastening sections 20a, 20b and the first and second receiving sections 10a, 10b in such a way that they comprise first and second fastening surfaces and first and second receiving surfaces. In particular, the first and second fastening surfaces and the first and second receiving surfaces have a roughness.

FIG. 5 shows a further preferred embodiment of a tensioning device 20 provided and fixed on a support element 10. In this embodiment, the tensioning device 20 is guided through the support element 10. In particular, the support element 10 has a through hole essentially coaxial with the through hole. It is also conceivable that the through bore receives a sleeve, at least in sections. The sleeve is designed in particular for power transmission between the tensioning device 20 and the support element 10. In particular, the clamping device 20 is arranged such that the clamping axis LS and the supporting axis LT of the supporting element 10 are arranged coaxially to one another. In this embodiment, the tensioning device 20 comprises a tensioning rope as a tensioning element. The tensioning cable is fastened to respective end sections in a first and second fastening element 20a, 20b designed as an anchor. In particular, the respective end sections of the tensioning cable are braced in the anchor. The anchors are in turn fastened in a preferred manner to the first and second receiving sections 10a, 10b of the support element 10. In the present embodiment, the support element 10 essentially forms the end and second receiving sections 10a, 10b. In particular, the first and second receiving sections 10a, 10b extend essentially perpendicular to the clamping axis LS and the supporting axis LT. The first and second receiving sections 10a, 10b can in particular be formed by a receiving element encompassed by the supporting element.

FIG. 7 shows a second preferred sequence of a method for prestressing 100 a support element 10 of a building 1 with a tensioning device 20. This preferred embodiment comprises, in addition to the steps of providing 110 and fixing 120 of the tensioning device 20 to the steps shown in FIG Support member 10, the steps of deforming 130 the jig with respect to an initial extension and transforming 135 the shape memory alloy of the jig 20.

FIG. 8 shows a third preferred sequence of a method for prestressing 100 a supporting element 10 of a building 1 with a tensioning device 20. This third particularly preferred sequence supplements the second preferred sequence of a method by the steps: relieving 140 of the tensioning device 20, heating 145 the shape memory alloy a phase transition temperature, converting 150 of the shape memory alloy from the martensite phase in a deformation state into an austenite phase of a memory state, and prestressing 160 of the support element 10 in dependence on a reset voltage of the shape memory alloy induced by a memory extension.

The first and second preferred sequence of the method for prestressing 100 are explained below in the course of a detailed description of the third particularly preferred sequence of the method. The method is described in particular with reference to the use of a tensioning device 20 for fastening to a bridge 1 according to FIG. 1a.

FIG. 1a shows a bridge 1 suitable for the road traffic of vehicles and people. The bridge 1 comprises a horizontally arranged on two abutments Structure. The bridge 1 preferably essentially comprises concrete, reinforced concrete, prestressed concrete, stone, steel. In the installed state or in the operating state, the supporting structure has corresponding roadway elements and walkway elements. In the present example, the supporting structure is to be understood as a supporting element 10 which is mounted on the abutment by means of a fixed / loose bearing. In the installed state or in the operating state, a tensioning device 20 is provided and fixed on the underside of the supporting structure. The clamping device comprises one of the shape memory alloys described above, in particular an Fe-Mn-Si shape memory alloy. Further preferably, the clamping device can have one of the shape memory alloys described in the patent specification EP 2 141 251 B1. In a particularly advantageous manner, the tensioning device 20 is suitable for prestressing the structure 10 of the bridge 1 in order to prevent or avoid further cracks in the concrete, or at least to minimize them. The lifespan of a bridge 1 which is prestressed accordingly with a tensioning device is preferably extended.

For this purpose, the tensioning device 20 is provided 110 and accordingly fixed 120 to the bridge 1. In particular, the tensioning device 20 is fixed 120 to the structure 10 with a first and second fastening section on a first and second receiving section 10a, 10b. The bridge 1 is now deformed as a result of the dead weight and the dynamic load of road traffic, the structure 10 bends downward between the abutments, the tensioning device 20 deforms accordingly. Preferably, the load 130 deforms the tensioning device 20 by 6% to 65% of the uniform expansion of the used Shape memory alloy. The deformation of the supporting structure 10 therefore leads to an advance of the tensioning device 20, in particular the shape memory alloy. Advantageously, pre-stretching, in particular cold rolling, skin-dressing or other industrial pre-stretching before assembly, that is to say from preparation and fixing, can then be omitted. In particular, this saves resources and costs.

The correspondingly deformed clamping device 20 thus converts 135 from an initial state with an austenite phase to the deformed state with the martensite phase. This phase transformation is in particular essentially due to the load F acting on the bridge and thus to a mechanical stress acting on the crystal structure of the austenite. This phase change leads to a deformation extension in the deformation state which is greater than the initial extension of the tensioning device 20 in the initial state. For preloading, bridge 1 is relieved 140, that is to say road traffic is blocked and unnecessary weight is removed from bridge 1. In particular, the clamping device 20 or the shape memory alloy is then heated 145 to a phase transition temperature, preferably between 25 ° C. and 400 ° C. 145. This results in the shape memory alloy being converted back 150 from the deformation state into the memory state, that is to say a phase transformation from the martensite phase to the austenite phase. In the present example, the memory extension is smaller than the deformation extension. As a result of this reshaping, a prestressing force acts on the supporting structure 10 from the tensioning device 20. In the present case, the reshaping is designed such that the maximum permissible crack width of the material of the supporting structure 10 is undershot. A prestress between 300MPa and 680MPa from the tensioning device 20 preferably acts on the structure. For prestressing 160, the supporting structure is to be reloaded accordingly, that is to say the measures and device taken to relieve the load are to be reversed or reversed again.

To retrofit existing structures 1 with a tensioning device 20, it is also conceivable to first relieve 130 the structure 1 or the respective support element 10 and then to provide the tensioning device 20 1 10 and to fix it 120 to the support element 10. Then the previously acting load is set F again, the supporting element 10 or the structure 1 deforms and accordingly the tensioning device 20. Depending on the extent of the relative transformation deformation, the further and previously described method steps from converting 135 to prestressing 160 can then be carried out for prestressing the structure 1.

The processes for prestressing or alternative designs described in FIGS. 2, 7 and 8 can apply equally to the motor vehicle shown in FIG. 1b or the section of a building shown in FIG. 1c. The methods are preferably also suitable for further possible designs of structures 1.

The motor vehicle shown as structure 1 in FIG. 1b comprises a body made of, for example, steel and / or aluminum as a supporting element 10. In the installed state or operating state, the underside of a tensioning device 20 provided and fixed thereon for pretensioning the body. With this arrangement, a body deformed, for example, by an accident - if the deformation does not exceed an allowable extension - can be converted into a memory state by heating to a phase transition temperature. Furthermore, FIG. 1 c shows a section of a building as a building 1, with a lintel 10 arranged horizontally on two posts, on the underside of which a fixing device 20 is fixed in the installed state or operating state.

FIG. 9 shows a further preferred sequence of a method for prestressing a support element 10 of a structure 1 with two tensioning devices 20. This preferred method is particularly suitable for support elements 10 or structures 1 which are essentially angular with a load F, in particular perpendicular to a support axis LT are applied to the support member 10 or the structure 1. In this preferred embodiment, two clamping devices are provided 1 10a, 1 10b and fixed to the support element 120a, 120b.

A correspondingly preferred embodiment is shown in FIG. 6. Here, a tensioning device 20 is provided and fixed on two opposite sides of a support element 10. This preferred embodiment is particularly suitable for support elements 10 of structures 1 which are essentially loaded with a load F transverse to the support axis LT, in particular with a bending moment. Analogously to the preferred embodiment shown in FIG. 3, the two clamping devices 20 are non-positively fixed to the first and second receiving sections 10a, 10b of the support element 10 by means of a clamp connection. With a load F acting perpendicularly to the supporting axis LT and the two clamping axes LS from above on the supporting element 19, the clamping device 20 arranged on the upper side in the installed state or operating state then acts as a pressure element 20 ′ and the clamping device 20 arranged on the lower side as a tension element 20 ".

REFERENCES

1 building

10 support element

10a, 10b first and second receiving section

20 tensioning device

20 'pressure element

20 “tension element

20a, 20b first and second fastening section

F load

LS clamping axis

LT support axle

Claims

EXPECTATIONS

1. A method (100) for prestressing a supporting element (10) of a building (1), comprising the steps:

Providing (110) a tensioning device (20) with a tensioning axis (LS),

wherein the tensioning device (20) comprises or consists of a shape memory alloy which has a one-way effect,

wherein the tensioning device (20) extends along the tensioning axis (LS) in an initial state with an initial extent between a first and a second fastening section (20a, 20b), and

Fixing (120) the tensioning device (20) in the initial state at least with the first fastening section (20a) on the first receiving section (10a) of the supporting element (10) and the second fastening section (20b) on the second receiving section (10b) of the supporting element (10) , wherein the tensioning device (20) has an austenite phase in the initial state.

2. The method (100) according to claim 1, comprising the steps:

Deformation (130) of the tensioning device (20) with respect to the initial extension by a relative transformation deformation as a function of the load (F) and

Converting (135) the shape memory alloy of the jig (20) from the

Austenite phase in the initial state into a martensite phase of a deformation state with a deformation extension along the span axis (LS).

3. The method (100) according to claim 2, comprising the steps:

Relieving (140) the tensioning device (20, 21) of the load (F), preferably by at least about 30% of the load (F),

Heating (145) the shape memory alloy of the tensioning device (20) to a phase transition temperature,

Converting (150) the shape memory alloy of the jig (20) from the

Martensite phase in the deformation state into an austenite phase of a memory state with a memory extension, and

Prestressing (160) the support element (10) as a function of a restoring voltage of the shape memory alloy of the tensioning device (20) induced by the memory extension.

4. The method (100) according to claim 3, wherein

the tensioning device (20) in the memory state is designed as a pressure element (20 '), provided that the memory extension is greater than the deformation extension.

5. The method (100) according to claim 3, wherein

the tensioning device (20) is designed as a tension element (20 ") in the memory state, provided that the memory extension is smaller than the deformation extension.

6. The method (100) according to any one of the preceding claims, wherein

the support element (10) extends in a main direction of extension essentially along a support axis (LT) and

the clamping device (20) with the clamping axis (LS) is arranged essentially parallel to the supporting axis (LT) and at a distance (D).

7. The method (100) according to any one of the preceding claims 1-5, wherein

the clamping device (20) with the clamping axis (LS) is arranged essentially transversely to the supporting axis (LT) of the supporting element (10).

8. The method (100) according to any one of the preceding claims, wherein the support element (10) is substantially loaded with a load (F) transverse to the support axis (LT).

9. The method (100) according to any one of the preceding claims, wherein the support element (10) is substantially loaded with a load (F) parallel to the support axis (LT).

10. The method (100) according to any one of the preceding claims 4-9, comprising the steps:

Providing (1 10a) a tensioning device (20 ″), which is designed according to claim 4, providing (1 10b) a further tensioning device (20 “), which is designed according to claim 5,

Fixing (120a) those designed as a pressure element (20 ') in the memory state

Tensioning device (20) on a side of the support element (10) which is subjected to pressure in the installed state of the support element (10), and

Fixing (120b) those designed as a tension element (20 “) in the memory state

Clamping device (20) on a side of the support element (10) which is subjected to tension when the support element (10) is installed.

11. The method according to any one of the preceding claims, wherein the shape memory alloy of the clamping device (20) is a shape memory alloy based on iron.

12. The method (100) according to any one of the preceding claims, wherein the shape memory alloy of the clamping device (20) is a shape memory alloy based on an Fe-Mn-Si alloy system.

13. The method (100) according to any one of the preceding claims, wherein the shape memory alloy of the clamping device (20) is a shape memory alloy, consisting of an alloy with the following alloy components in weight percent:

25.0% <Mn <32.0%,

3.0% <Si <8.0%,

3.0% <Cr <10.0%,

0.1% <Ni <4.0%,

P S 0.1%

S S 0.1%,

Mo <0.5%,

Cu <0.5%,

AI S 5.0%,

Mg <5.0%,

O S 0.1%,

Ca <0.1%,

N S 0.1%,

C S 0.1%,

B <0.1% and the following applies to the sum of the group 1 alloy components:

Ti s 1, 5%,

Nb s 1, 5%,

WS 1, 5%, VS 1, 5%,

Group 2 and for the ratio of the sum of the alloy components of group 1 and group 2, in each case in atomic%:

0.5 2.0

with the rest iron and unavoidable impurities.

14. The method (100) according to any one of the preceding claims, wherein the shape memory alloy of the clamping device (20) is a shape memory alloy, consisting of an alloy with the following alloy components in weight percent:

25% - 30% Mn,

4% - 8% Si,

3% - 7% Cr,

0.5% - 1% V,

0.1% - 0.5% C, and

Rest of iron and unavoidable impurities.

15. Use of a tensioning device (20) for permanent attachment to a structure for carrying a load (F) and for applying tension to secure the structure,

wherein the clamping device (20) comprises or consists of a shape memory alloy which has a one-way effect and, in an initial state with an initial extension, extends between a first and a second fastening section (20a, 20b) along a clamping axis (LS),

wherein the shape memory alloy of the tensioning device (20) has an austenite phase in the initial state, and

wherein the tensioning device (20) is not pre-stretched in the initial state.

16. Use according to claim 15,

wherein the tensioning device (20) extends along the tensioning axis (LS) in a deformation state with a deformation extension between the first and the second fastening section (20a, 20b), and

wherein the tensioning device (20) deforms with respect to the initial extension by a relative transformation deformation as a function of a load (F) and the shape memory alloy of the tensioning device (20) changes from the austenite phase in the initial state into a martensite phase of the deformation state.

17. Use according to claim 16,

wherein the tensioning device (20) extends along the tensioning axis (LS) in a reminder state with a reminder extension between the first and the second fastening section (20a, 20b),

wherein the shape memory alloy of the tensioning device (20) has an austenite phase in the memory state, and

wherein the tensioning device (20), which is relieved of at least about 30% and heated to a phase transition temperature, changes from the martensite phase in the deformation state to the austenite phase in the memory state, and

the tensioning device (20) prestresses the structure (1) in the memory state.

18. Use according to any one of the preceding claims 15-17, wherein the structure (1) is a bridge.

19. Use according to any one of the preceding claims 15-17, wherein the structure (1) is a building.

20. Use according to any one of the preceding claims 15-17, wherein the structure (1) is a vehicle.

21. Use according to one of the preceding claims 15-17, wherein the structure (1) is a high-bay warehouse.

22. Use according to any one of the preceding claims 15-17, wherein the structure (1) is a pipeline.

23. Use according to any one of the preceding claims 15-17, wherein the structure (1) is a carrier.

24. Use according to any one of the preceding claims 15-17, wherein the structure (1) is a rod structure.

25. Use according to any one of the preceding claims 15-17, wherein the structure (1) is a machine.