EP1311734A2

EP1311734A2 - Device for tightening reinforcing elements

Info

Publication number: EP1311734A2
Application number: EP01974193A
Authority: EP
Inventors: Josef Scherer
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-08-16
Filing date: 2001-08-15
Publication date: 2003-05-21
Also published as: WO2002016710A3; WO2002016710A2; AU2001293776A1

Abstract

The invention relates to a device for tightening reinforcing elements, particularly unidirectional fibre laminates with a high strength of extension and one such elastic modulus connected to structures or parts of structures particularly structures with cement subjected to bending stress. The device comprises at least one tensioning means (SM) supplied with a mechanical drive. The tensioning means enters into contact with a first coupling member (K1) connected to at least one reinforcing element (V) and with a second coupling member (K2) connected to the structure (B). Non-uniform distribution of tension is avoided, especially along the width of the strip-type reinforcing elements, in addition to uncontrolled slackening of the tension during hardening of the conglutination before highly solid shear connection between the laminate and the concrete; correspondingly creation of tensioning devices of the above-mentioned variety for improved quality and reliability of the reinforcements in a rational manner of production. During the pre-tensioning flow of force between the connection of the first coupling member to the reinforcement element and the connection of the second coupling member to the structure, at least one pivoting connection (S1 or S2) is provided with at least one pivoting axis (A) arranged at an angle, especially an oblique angle, with respect to the tensioning device (X).

Description

Device for tensioning reinforcing elements.

The invention relates to a device for tensioning reinforcing elements, in particular unidirectional fiber laminates of high tensile strength and the same tensile modulus, which are connected to structures or structural parts, in particular those with bending-stressed concrete. In this case, at least one tensioning means provided with a power drive is provided, which acts on the one hand on a first coupling member connected to a reinforcing element and on the other hand on a second coupling member connected to the building or part of the building. In general, it is understood in the present context that buildings and components are addressed in the same sense and therefore do not require any further differentiation without special requirements.

Devices of the type mentioned are known as a technique for the pretensioning of high-strength fiber laminates, such as those stuck on for repair and for the subsequent expansion of the load limits. It has been found in practice that the quality of the reinforcement is often due to non-uniform pre-stress distribution, especially across the width of the strip-shaped reinforcement elements, and also due to uncontrolled release of the pre-stress applied during the curing of the bond, i.e. before the high-strength shear connection between Laminate and concrete. Accordingly, the object of the invention is concerned with the creation of tensioning devices of the present type, which enable improved quality and reliability of the reinforcements with a rational production method. The solution to this problem according to the invention is determined by the totality of the features of claim 1 and the independent claims 7 and 13, respectively. These solution variants are based on a common inventive idea. This consists in the knowledge that there is a largely common criterion for the quality of a reinforcement of the present type, namely the precision of the compliance with specified stress parameters. On the one hand, this is the fluctuation range of the tensile stresses generated in the cross section of the reinforcing element and, on the other hand, the minimum and maximum values of the tensile stress in the element cross section.

The features of claim 1 open up the basic possibility of compensating for angular deviations - in the further developments according to claims 2 or 5 or 6 even transverse offset - between the axes of action of the prestressing means and the reinforcing element, i.e. an equalization of the stress distribution within the element cross section.

The features of claim 7 allow - complementary or alternatively to the features of claims 1 or 13 - extensive maintenance of a predetermined and achieved tension value, namely by means of a tensioning drive or a backstop in the area of the tensioning means.

The same also applies to the combination of features of claim 13 with regard to the control loop created thereby for an accurate and reliable setting and maintenance of predetermined target values or limit values of tensile stresses in reinforcing elements. In practice, these are generally prestressed reinforcing elements in or on cross-sectional parts of the building that are under tension. The prestressing therefore relieves the existing reinforcement or puts the concrete under a resulting compressive stress and increases safety against cracking.

The invention is further explained with reference to the exemplary embodiments shown schematically in the drawings. It shows:

1 shows a side view of a laminate tensile reinforcement with tensioning device attached to the underside of a concrete ceiling,

2 shows a bottom view of the arrangement according to FIG. 1,

3 shows a view corresponding to FIG. 2 of a tensioning device

Hobbing pressure body

4 shows a view corresponding to FIG. 2 of a tensioning device with a rotatably mounted rolling pressure element,

5 is a plan view of a drive with a multiple

Wedge arrangements acting tensioning or re-tensioning and return lock device,

6 shows an axial section of a hydraulic cylinder

Piston unit trained drive unit for a clamping device and

7 shows a functional circuit diagram of a tensioning device

Limitation and liability control loop. The arrangement shown in FIGS. 1 and 2 comprises an elongated-striped reinforcement element V arranged on the ceiling surface of a concrete structure B, for example in the form of a preferably essentially unidirectional fiber laminate of high strength and the same tensile modulus. In an end region E, the reinforcement element is already bonded to the ceiling surface with full shear strength in the initial state of the prestressing process and, if necessary, is additionally additionally bonded to a rigid anchor element AK, which in turn is connected directly to the concrete of the building, for example by dowels D. In the opposite copying area, the reinforcement element is glued flat and also highly rigid to a plate-shaped first coupling element Kl, which in turn - at least during the tensioning process - is not attached to the concrete ceiling, but is arranged to be displaceable relative to it. Under or after provisional support and securing of the distance from the ceiling surface, the reinforcement element V fixed on the one hand with anchoring AK to the ceiling and on the other hand firmly connected to the coupling element Kl by the hardened adhesive bond on its upper side facing the ceiling with a suitable for high-strength connections Apply slowly curing adhesive. Then, in the longitudinal direction of the reinforcing element at a distance from the first coupling element K1, a second coupling element K2, which is likewise plate-shaped in the example, can be subjected to high loads by means of dowels D, in particular in a shear-resistant manner, in such a way that this coupling element K2 shares the small thickness of the laminate reinforcing element V with overlaps a sufficient distance C so as not to impede the tensioning and possibly stretching process of the reinforcing element. The latter is then brought into contact with the ceiling surface and, if necessary, temporarily secured in this position. Clamping means SM are then attached to the underside of the coupling element K2, which in the example comprises a hydraulic clamping cylinder SZ with a piston rod KS and an articulated head GK at the end. The latter is connected by a swivel connection S1 designed as a pivot joint with a swivel axis A directed transversely to the piston rod KS to a compensating member AG designed as a two-joint bracket, which in turn is connected to the first coupling member Kl by means of such a swivel connection S2. This results in a preloading force flow in the clamping direction X from the clamping cylinder SZ via the two-joint compensating member AG to the head end K of the reinforcing element. Due to the above-mentioned swivel connections and the compensating member AG which is switched into the flow of force and which can be swiveled transversely to the tensioning direction and parallel to the ceiling plane, misalignments and misalignments which cannot be easily remedied using conventional measuring and straightening means without an increased amount of work and are asymmetrical Stress distribution in the reinforcing element cause, largely reduced or even practically automatically balanced. The arrangement of the compensating element as an element acting under tensile forces has the advantage that - with adequate rigidity or freedom from play of the piston rod or its mounting - there is no increase in error due to buckling.

Furthermore, in the embodiment according to FIGS. 1 and 2, clamping means provided with a backstop device RSP and optionally also with a tensioning effect are provided. For this purpose, pivoting wedges SK are articulated on the coupling member K2 by means of journal bearings Z symmetrically to the pull axis. The correspondingly curved wedge pressure surfaces KD act on swivel drives AS on abutment journals WL of the first coupling member Kl under the effect of, for example, conventional swivel drives AS, which are therefore only indicated here by arc arrows, by means of appropriate design and dimensioning Self-locking with respect to the swivel movement. The self-locking can be designed positively by means of sufficiently fine and appropriately asymmetrical, sawtooth-like teeth. These wedge gears, which are supported against each other transversely to the tension axis and therefore do not load the guides of the tensioning drive, not only act as an automatically moving backstop to protect against failure of the tensioning drive, but can also be retightened if the swivel drive is sufficiently strong if the reinforcing elements give in or creep cause, especially in the course of curing the bonds between reinforcement and concrete, if - as is desired - the extensive main drive of the tensioning device is removed relatively early and used otherwise.

In the embodiment according to FIG. 3, to the extent that shown in FIGS. 1 and 2, a strip-shaped laminate reinforcing member V with a first coupling element K 1 on the head side and associated pivot connection S1 and compensating member AG is provided. Here, however, a second swivel connection S2a is provided, which has a rolling pressure body WD interacting with a counter pressure surface GD. This construction is characterized by simplicity and robustness.

4 shows a construction similar to the preceding one, but with the essential difference that a pivot connection Sla is provided with a rotatably mounted, roller-shaped rolling pressure body Wda and with a counterpressure surface Gda concave in the direction opposite the clamping direction X. This training enables extensive escape error compensation as well as in many cases sufficient offset error compensation with a self-centering effect, which allows a compact construction with only one swivel connection Sla. In contrast, the embodiment according to FIG. 5 is a clamping device with a double wedge gear, which is formed by a driving wedge pair KL1 and a driven wedge pair KL2. A spindle S with, for example, the usual rotary rotary drive AS (only indicated as a bow arrow) causes the wedge pair KL1 to move together and thus to move the wedge pair KL2 apart, which represents the clamping movement in the direction X, according to arrows P. This wedge gear can also be advantageously designed simply with sufficient self-locking.

FIG. 6 shows a tensioning drive with a clamping device operated or activated as a backstop means RSP by means of a pressurized fluid. For tensioning in direction X, the pressure side DS of a piston KO located in a tensioning cylinder SZ is acted upon by pressure fluid via a feed connection (not shown). Separated from this tensioning drive part by sealing means Dia is a cylinder section acting for the anti-return means, within which the piston rod KS is surrounded by a radial contact surface BF by a clamping sleeve KH which is under high radial pressure and is secured in the cylinder against axial displacement. An outer gap space SA formed on the outside of the clamping sleeve is provided with sealing means D2 and is normally kept pressure-free via a drain AF. However, this connection can optionally also be provided by means of suitable valve and control means for an additional clamping pressure. In this state, the piston rod is locked in place by the clamping friction and is therefore locked against reverse in the extended position (not shown). To unlock the clamping operation, the gap SR formed by surface roughness between the piston rod and clamping sleeve is connected via a pressure connection DA filled with pressure fluid and thus the clamping sleeve is subjected to an internal pressure which is sufficient for an elastic expansion of the sleeve and thus for a release of the piston rod. In order to maintain this gap pressure, end-side sealing means D1 are provided between the clamping sleeve and the piston rod KS in addition to the sealing means Dia already mentioned.

The control and regulating device shown in FIG. 7 comprises, in a simplified representation, tensioning means SM similar to the embodiment according to FIGS. 1 and 2, but with a pressure-operated clamping backstop RSP, e.g. such according to Fig. 6. It goes without saying that automatic backstops, possibly with tensioning means, can also be used here instead of the controlled backstop, which simplifies the control technology.

The system shown comprises a pressure fluid source DQ, which acts on the feed port E1 of the tensioning cylinder SZ with pressure fluid via an electromagnetically controllable switching valve VS1 and switches on the tensioning process on the reinforcing element in direction X. A pressure measuring element DMG is inserted in the feed line between valve VS1 and connection El, the output of which is connected to one of two difference-forming inputs of a comparator VG. The other input of the latter is connected to an adjustable limit transmitter GWG. The output of the comparator VG interrupts the supply of pressurized fluid when the predetermined limit value of the clamping pressure is reached by appropriately activating the valve VS1 and thus ends the clamping process. Until then, the clamping backstop RSP had been deactivated for the purpose of releasing the clamping process, namely by connecting the clamping device through an E2 Also controlled by the comparator VG, the second switching valve VS2, which is in the open state, acted upon by the pressure fluid source and the clamping was released. However, the comparator now reverses the switching valve VS2, so that the connection E2 is separated from the pressure fluid and connected to the outlet, that is to say it is relieved. The clamp backstop is now activated according to the example in Fig. 6, and the pre-tensioned state is maintained until the bond between the reinforcing element and the structure has fully hardened.

The overall result is a tensioning device which comprises power-driven tensioning and tensioning means with backstop. What is essential in the sense of a control loop is the DMG clamping force transducer, which is in operative connection with the reinforcing element to be tensioned or with the clamping means, and which supplies a clamping force signal corresponding to the voltage reached in the reinforcing element, and the limit value transmitter GWG, which corresponds to a limit value signal corresponding to the clamping force signal supplies. An integral part of this special control circuit is also the comparison device VG, which is controlled by the tension force measuring device and the limit value transmitter, which in turn controls a device operatively connected to the tensioning means, comprising the already mentioned components VS2 and SP for limiting the tensioning force in such a way that compliance and maintenance of predetermined tension values of the Reinforcing element can be maintained up to a sufficient solidification of the integral connection with the building.

Claims

claims

Device for tensioning reinforcing elements, in particular unidirectional fiber laminates with high tensile strength and the same tensile modulus, which are connected to buildings or structural parts, in particular those with bending-stressed concrete, with the following features: It is at least one tensioning device (SM) provided with an IC power drive provided that engages on the one hand with a first coupling element (K) connected to at least one reinforcing element (V) and on the other hand with a second coupling element (K2) connected to the structure (B), characterized by the following features: in the course of the prestressing force flow between the connection of the first coupling member to the reinforcing element and the connection of the second coupling member to the building is provided with at least one swivel connection (S1 or S2) with at least one swivel axis (A) arranged at an angle, in particular transversely, to the clamping direction (X).

Clamping device according to claim 1, characterized in that in the course of the pretensioning flow between the connection of the first coupling member (Kl) to the reinforcing element (V) and the connection of the second coupling member (K2) to the structure (B), two swivel connections ( Sl, S2) are provided, which are arranged at a mutual distance in the direction of action (X) of the reinforcing element and are connected to one another in a positive or non-positive manner.

3. Clamping device according to claim 2, characterized in that two pivot connections are arranged in the region between the clamping means (SM) and the first coupling member (Kl) and are connected to one another by a movable compensating member (AG) which transmits clamping force.

4. Clamping device according to one of claims 1 to 3, characterized in that at least one of the pivot connections has at least one rolling pressure body (WD. Wda) interacting with a counter pressure surface (GD, Gda).

5. Clamping device according to claim 4, characterized in that the rolling pressure body (WDa) is rotatably mounted.

6. Clamping device according to claim 4 or 5, characterized in that at least one counter pressure surface (Gda), which extends at least in sections transversely to the clamping direction and is concavely curved or curved toward the rolling pressure body (Wda), is provided.

7. Device for tensioning reinforcing elements, in particular unidirectional fiber laminates with high tensile strength and the same tensile modulus, which are connected to structures or structural parts, in particular those with bending-stressed concrete, in particular tensioning device according to one of the preceding claims, with the following features:

At least one tensioning device (SM) provided with a power drive is provided, which on the one hand is connected to a first coupling member (Kl) connected to at least one reinforcing element (V) and on the other hand is connected to the first coupling member (B) second coupling element (K2), characterized in that for the tensioning means (SM) the stretching of the reinforcing element achieved during the tensioning process is provided with positive and / or non-positive tensioning means and / or anti-return means (SP).

8. Clamping device according to claim 7, characterized by locking means designed with respect to the return with positive and / or non-positive self-locking.

9. Clamping device according to claim 8, characterized by means of, in particular, asymmetrical toothing, positively self-locking return-blocking means.

10. Clamping device according to one of claims 7 to 9, characterized by return locking means provided with at least one wedge gear.

11. Clamping device according to claim 7, characterized by means of at least one clamping device non-positively secured return-blocking means.

12. Clamping device according to one of the preceding claims, characterized by motorized, in particular by pressure fluid, operated or activatable return-blocking means.

13. Device for tensioning reinforcing elements, in particular unidirectional fiber laminates of high tensile strength and the same tensile modulus, which are connected to structures or structural parts, in particular those with bending-stressed concrete, at least one tensioning means (SM) provided with a power drive being provided, that acts on the one hand on a first coupling element (Kl) connected to at least one reinforcing element (V) and on the other hand on a second coupling element (K2) connected to the structure (B), in particular a tensioning device according to one of the preceding claims, characterized by the following features: a ) There is a clamping force transducer (DMG) which is operatively connected to the reinforcing element to be tensioned or to the tensioning means and which delivers a tension force signal corresponding to the tension reached in the reinforcing element; b) there is a limit value transmitter (GWG) which supplies a limit value signal corresponding to the clamping force signal; c) There is a comparison device (VG) controlled by the tension force measuring device and the limit value transmitter, which in turn controls a device (VS2, SP) for limiting the tension force that is operatively connected to the tensioning means in such a way that predetermined tension values of the reinforcing element are maintained.

14. Clamping device according to claims 7 and 13, characterized in that the clamping force limit value comparison device is in an activating control connection with the re-tensioning means or anti-return means.

15. Clamping device according to claim 13 or 14, characterized in that a pressure medium-operated clamping means (SM) is provided with a pressure limiting control loop for setting predetermined voltage values for the reinforcing element (V).

16. Clamping device according to claim 15, characterized in that the pressure-limiting control loop for setting predetermined pretension values is coupled to a clamping device in such a way that activation of the clamping device is connected when a predetermined voltage value is reached.