WO2008148379A1

WO2008148379A1 - Girder element for concrete formwork comprising a structure for automatically compensating bending strains

Info

Publication number: WO2008148379A1
Application number: PCT/DE2008/000928
Authority: WO
Inventors: Hans Braun
Original assignee: Peri Gmbh
Priority date: 2007-06-05
Filing date: 2008-06-03
Publication date: 2008-12-11
Also published as: CA2687832C; CA2687832A1; US20100115860A1; DE102007026499B3

Abstract

A girder element (1; 21; 31; 41; 53-57) for concrete formwork comprises a girder (4) for receiving external forces (10), a tension rod (5) extending behind the girder (4) and at least one lengthwise adjustable tensioning device that is interposed between the girder (4) and the tie rod (5), the local distance between the girder (4) and the tie rod (5) being adjustable by means of said tensioning device. The invention is characterized in that the lengthwise adjustable tensioning device is configured as a lengthwise adjustable compensation device (6; 6a, 6b) which is motor driven to adjust the length of the compensation device (6; 6a, 6b). A measuring device is used to determine the position (x) of the girder (4) in the area of the compensation device (6; 6a, 6b) relative to a desired position (xs). A control device (12) is used to adjust the length (L) of the compensation device (6; 6a, 6b) depending on the position (x) of the girder (4). The girder element according to the invention allows the precise and cost-effective manufacture of any concrete structures.

Description

Support element for a concrete formwork with device for automatic compensation of bending deformations

The invention relates to a support element for concrete formwork, in particular a ceiling support element, with a support for receiving external forces, with a drawstring, which runs behind the support, and with at least one length-adjustable tensioning device, which is arranged between the support and drawstring, with the local distance of carrier and drawstring is adjustable.

Such a carrier element has become known, for example, from the company publication "Column Hung System" by HI-LITE Systems, div of JASCO Sales Inc., Mississauga, Ontario, Canada, 2001.

For the production of concrete structures often formwork technology is used. In the process, a structure of the building, such as a wall, pillar or ceiling, to be fabricated, is reshaped with shuttering elements and poured with liquid concrete.

The formwork elements, which are exposed directly to the liquid concrete with a formwork skin, are backed with a support structure intended to hold the formwork elements in a desired position. A support structure usually comprises a plurality of support elements which are partially fixedly connected to each other (longitudinal and transverse beams), and are partially fixed or supported on solid structures (such as already completed building parts such as a storey column or a basement floor).

By the weight of support elements, and especially by the weight of overlying or adjacent other support elements and liquid concrete, support elements can be deformed. Deformed support structures generally lead to undesirable deviations in shape of the finished concrete structure from the desired concrete structure.

Here is an example: When producing a floor slab with a surface area of 10m x 10m in formwork technology, weights of approx. 10t for formwork and approx. 75t for liquid concrete typically occur. When fastening the support structure to four square floor pillars, under load, conventional support elements cause a deflection of approx. 7 cm. By a sufficiently large number, ie density, of fastening and support points deformations in the support structure can be reduced. However, a high density of support points is associated with a high work and material costs in the construction of the formwork. Furthermore, suitable solid structures for supporting or securing a support structure are not sufficiently available for some concrete structures to be manufactured. In the production of floor slabs, for example, often the production of a next higher floor slab should already be started when the underlying slab is not fully cured; then the next higher ceiling or its support structure must be attached only to already hardened Geschosssäulen.

In order to create a desired concrete structure even with a low density of mounting and support points of a support structure, on the one hand as rigid as possible support elements are used. From the cited company publication "Column Hung System" support elements have become known for a slab formwork construction, which have a truss-like frame with two parallel straps and extending between the straps, partially inclined rungs.The upper strap serves as a support for other support elements or formwork beams and formwork elements There is a drawstring underneath the lower belt and a tensioning device between the lower belt and the drawstring (underlaid truss girders) .These known girders, while being highly rigid, are heavy in weight and are therefore difficult to work on site Due to the large amount of steel consumed in the production process, they are expensive to handle and, with these support elements, the problem of deformation can only be reduced, but not completely eliminated.

On the other hand, an attempt is made to predict the bending deformation of carrier elements under the expected load. The support elements are prepared (for example, with Überhöhungsleisten) so that they are without load one for the structure to be produced initially undesirable curvature, but under load adjusts a desired for the concrete structure to be produced shape. However, the precalculation of the bending deformation is time-consuming and difficult and has to be carried out individually and in each case for each concrete structure to be produced and also for each support element. A specially prepared carrier element can usually only be used for a single concrete structure to be produced at a specific location of the carrier structures. Furthermore, compliance with the desired ceiling thickness is difficult because the formwork deflection changed during the concreting process.

Object of the invention

It is the object of the present invention to present a support element with which any concrete structures can be manufactured accurately and inexpensively.

Brief description of the invention

This object is achieved by a carrier element of the type mentioned, which is characterized in that the adjustable-length clamping device is designed as a length-adjustable compensation device with a motor drive for Einsteilung the length of the compensation device that a measuring device is provided by the position of the carrier around

Compensating device can be determined relative to a desired position, and that a control device is provided, through which the length of the compensation device in dependence on the position of the carrier is controllable.

It is the basic idea of the present invention, the shape of a carrier element, and in particular the curvature of the carrier of the carrier element, by a length-adjustable compensation device to decide and adjust. Depending on the external forces acting on the carrier, the length of the compensating device is chosen so that the desired shape (usually a straight shape) of the carrier is established. According to the invention, the length of the compensating device can also be adjusted under load, in particular readjusted, by the motor drive.

The carrier has a (usually straight) front side over which the external forces can act on him. On this front, for example, other support elements or formwork support are on or. Above the opposite side of the carrier runs a drawstring, usually slightly oblique to the carrier. The outer ends of drawstring and carrier are typically connected together; the outer ends of the carrier are also usually attached to solid structures. In general, there is a further connection between the carrier and tension band on the

Compensation device. The drawstring is under tension, while the carrier and optionally other pressure belts are under compressive stress. If an external force now acts on the carrier, which tries to deform it (press in), then with the compensating device a spreading force can be exerted between the carrier and the tension band, which holds the carrier in the previous form. The compensation device then causes under load a redistribution of the elastic deformation in the carrier element, namely from the carrier to the tension band.

The deformation of the carrier by external forces, such as the weight of liquid concrete, and further by the weight of the support member, so a deformation of the carrier is superimposed by the compensation device. The shape of the carrier is monitored by comparing a measured actual position of the carrier with a desired position. The nominal position of the carrier is absolutely by the to be built

Concrete structure specified; the actual position of the carrier, however, is a function of the applied load, the dead weight of the carrier element and the length adjustment of the compensation device. For position determination the carrier is a measuring device that passes on their measurement results (usually in electronic form) to a (also usually electronic) control device. If the actual position of the carrier deviates from the desired position, a change in length of the compensation device is actuated which brings the carrier closer to its desired position. By a continuous control of the carrier can be fully automatically kept at the desired position.

By adjusting the shape of the carrier by means of a measuring and control system, a desired shape of the carrier of the carrier element can be maintained in principle any desired loads. Predictions of the load are not required (within a maximum load of the support member). Overall, the carrier element need not be particularly resistant to bending, since deformation of the carrier is prevented by the length-adjustable compensation device. As a result, the carrier element according to the invention can be constructed relatively easily and with low material, whereby it is easy to handle when assembling and dismantling a formwork. Weight savings of up to 50% can be achieved compared to conventional carrier elements.

In general, it is sufficient to describe the formwork deformation of a carrier by the position of a measuring point of the carrier and to compensate for the deformation of the carrier by means of a compensation device (per carrier element). In the context of the invention, however, a plurality of measuring points and / or a plurality of compensating devices may be provided per carrier / carrier element in order to increase the accuracy of the compensation. Preferably, a measuring point is then provided for each compensation device. A measuring point is preferably located on the carrier / carrier element as close as possible to the associated compensation device.

An additional advantage of a carrier element according to the invention lies in a simplified stripping of formwork elements. The carrier element can be lowered and / or retracted by operating the compensation device (lowering the pressure).

In the context of the invention, it is usually sufficient if the length-adjustable compensation device can build up pressure in one direction (piston side) (can apply a spreading force between the carrier and the drawstring, for example). a plunger cylinder can be used. In individual cases, however, the use of double-acting cylinder can be useful, for example, for the compensation of deformations of high formwork in strong wind.

Preferred embodiments of the invention

In a preferred embodiment of the carrier element according to the invention, the motor drive comprises an electric drive, in particular a linear motor. Such a drive is simple and easy to maintain.

In an equally preferred alternative embodiment, the motor drive comprises a hydraulic drive or a pneumatic drive. With a hydraulic drive particularly large forces can be applied. As hydraulic agents are particularly water and oil into consideration. Water does not cause any damage on site leaks. Due to the slow passage of deformation paths during concreting can for pressure supply and pressure maintenance in water on conventional high-pressure cleaning equipment (or their

Assemblies) are used. In hydraulic or pneumatic actuators, a common pressure supply for a variety of compensation devices, in particular by different support elements, take place; the force control at the individual compensation devices then takes place by means of local controllable valves, either in the supply lines of the compensation devices or directly at the respective compensation device. Note that the motor drive may include a mechanical adjustment device (such as gears, spindles or wedges) driven by the motor drive.

Also preferred is an embodiment in which the measuring device comprises a spacer rod or a rope with pulley and ballast or a laser rangefinder. A spacer bar and a rope with ballast are very simple measuring devices. A laser rangefinder is particularly easy to install.

Particularly preferred is an embodiment of a carrier element according to the invention, in which the compensation device is length-adjustable in a direction which extends substantially perpendicular to the carrier. This ensures an effective and even force entry into the carrier.

In another preferred embodiment, the carrier element has at two opposite ends of the carrier fastening means for the carrier element, in particular for attachment to projectile columns. This embodiment is particularly suitable for slab formwork, with larger distances (typically 7m to 10m) spanned by a girder structure. In this embodiment, no further attachment or support points are provided except at the opposite ends of the carrier. Alternatively, the fastening means may also be designed for attachment to other carriers.

Very particularly preferred is an embodiment in which the carrier is designed to be telescopic. As a result, the carrier element can be adjusted to a length to be spanned.

Also preferred is an embodiment which provides that the carrier has fastening means for fastening a plurality of formwork carriers on the carrier. This increases the safety of the overall construction. In another advantageous embodiment, a plurality of length-adjustable compensation devices are provided, which are distributed over the length of the carrier. As a result, a more precise compensation of a deformation of the carrier can be achieved, in particular if an asymmetrical deformation (for example with one-sided attachment of the carrier element) is to be compensated. Each compensating device preferably has its own measuring and control device. Furthermore, a substantially uniform distribution of the compensation devices via the carrier element is preferred.

Also advantageous is an embodiment in which a signal device is provided which outputs a warning signal when a limit value for the position of the carrier is exceeded, in particular an acoustic, optical or electronic warning signal. By means of the warning signal, when the compensation device is overloaded (i.e., a deformation compensation is not or no longer completely possible), safeguards can be initiated.

The scope of the present invention also includes the use of carrier elements according to the invention for constructing a concrete lining, in particular for forming a slab formwork. These concrete formworks have a high manufacturing accuracy, and can be used in particular free of formwork deformations. Since support elements of lightweight design can be used universally the construction and disassembly of the formwork according to the invention is low in labor and therefore cost.

Also within the scope of the present invention is a use of a support member according to the invention for continuously compensating bending deformations of the support, wherein a variable external force acts on the support, in particular wherein the external force on the support is caused by the weight of concrete.

Further advantages of the invention will become apparent from the description and the Drawing. Likewise, according to the invention, the above-mentioned features and those which are still further developed can each be used individually for themselves or for a plurality of combinations of any kind. The embodiments shown and described are not to be understood as exhaustive enumeration, but rather have exemplary character for the description of the invention.

Drawing and detailed description of the invention

The invention is illustrated in the drawing and will be explained in more detail with reference to embodiments. It shows:

1 shows an embodiment of a carrier element according to the invention for a slab formwork, in a schematic side view;

2a shows a support structure for a slab formwork with carrier elements according to the invention, in a schematic oblique view; and

Fig. 2b, the support structure of Fig. 2a with launched

Formwork beams and formwork elements, in a schematic oblique view.

1 shows an embodiment of a carrier element 1 according to the invention, which is used to build a slab formwork (cf. also FIGS. 2a, 2b) and is fastened to two projectile columns 2, 3. It should, for example, a flat, horizontal ceiling are made.

The support element 1 has an upper support 4, on whose (in Fig. 1 overhead) 14 further support elements or formwork support or formwork elements can be placed and / or fixed (not shown). The carrier 4 is preferably telescopic and consists for example of one or more steel profiles. Behind the support 4 (in Fig. 1 below the support 4) extends a tension band 5, which is stretched in a V-shape. The drawstring 5 is fixed in the middle at a lower end of a length-adjustable compensation device 6. The outer ends of the drawstring 5 are connected via fastening means 7a, 7b to the outer ends of the carrier 4. The drawstring 5 (or each section of the drawstring) is designed, for example, as a wire rope or as a solid rod or as a steel tube. The fastening means 7a, 7b are additionally connected to one another by a pressure rod 8. The pressure rod 8 may be formed, for example, as a solid steel rod or as a steel tube (Note that also the carrier 4 itself can act as a push rod or acts). Furthermore, the carrier 4 is connected at the center to the upper end of the compensating device 6 via a connecting member 13 (e.g., rod, linkage, punch of a cylinder). The compensation device 6 is adjustable in length in Fig. 1 in the vertical direction by a power drive.

About the attachment means 7a, 7b, the support member 1 with the Geschosssäulen 2, 3 is firmly connected (ie, the outer ends of the support 4 are also fixed under load). A direct attachment or support of the support element 1 on an already manufactured floor slab (ie the floor) 9 does not exist, for example because the floor slab 9 is not sufficiently cured. In addition, the support element 1 could be supported near a floor pillar 2, 3 still on a support on the ground, because premature loading of a floor ceiling is possible in these areas. The carrier element 1 spans the intermediate space between the projectile columns 2, 3.

If external forces 10 (in FIG. 1 from above) are now introduced into the carrier 4, in particular due to the weight of resting formwork carriers, formwork elements and liquid concrete, the carrier 4 begins to bend downwards in the middle. In other words, the distance x of the carrier 4 to the bottom 9 decreases.

The distance x of the carrier 4 from the bottom 9 (ie the position of the carrier 4) is monitored with a laser rangefinder 11 and compared in a control device 12 with a target distance xs. The setpoint distance xs corresponds to the position of the undeformed, straight carrier 4. The laser rangefinder 11 is arranged in the region of the compensation device 6.

Now falls the distance x below the setpoint xs, the control device 12 an increase in the length L of the compensation device 6 at. This leads to a lifting of the carrier 4 and a (depending on the E-modulus of the

Tension band stronger or weaker) depression of the tension band 5 in the central region in the vicinity of the compensation device 6. As a result, the carrier 4 can be maintained at a constant level.

Typically, throughout the concreting and curing of the ceiling to be manufactured, the position of the support 4 is maintained at the desired position, i. the distance x on the target distance xs. Thus, the carrier 4 always remains approximately straight, and the ceiling receives the desired, planar shape.

Figures 2a and 2b illustrate the use of carrier elements according to the invention in a support structure for a slab formwork for the production of a floor slab. Fig. 2a shows an already finished, but not yet fully cured floor slab (floor) 9, from the four projectile columns 2, 3, 51, 52 protrude. The Geschosssäulen 2, 3, 51, 52, are already fully cured.

The new floor to be manufactured ceiling is to be built, the associated slab formwork should be attached or supported only on the Geschosssaululen 2, 3, 51, 52, but not on the not fully loadable bottom 9. This is a support structure with a total of five invention Carrier elements 53-57 and another carrier 58 used.

Only the two support members 53, 54 are fixed to the outer ends of their support 4 to fixed structures, namely the Geschosssäulen 51, 2 and 52, 3, (and thus always fixed with these outer ends under load). The attachment takes place with anchors in the respective column body and a support on a frame 62 which engages around the respective pillar. The carriers 4 of the carrier elements 53, 54 are also referred to as yoke carriers.

On the Jochträgem the support members 53, 54, the carrier 4 of the three other support elements 55, 56, 57 according to the invention are placed (supported) and fixed. The carrier 4 of the support members 55-57 are also referred to as cross member; they are telescopic (i.e., variable in length). The carriers 4 of the carrier elements 53, 54 and 55, 56, 57 intersect at right angles.

Each support element 53-57 according to the invention each have a length-adjustable compensation device 6 with a motor drive (not shown in detail), with which the local distance of a drawstring 5 from the carrier 4, i. the distance (measured perpendicular to the carrier 4) in

Area of the compensation device 6, can be adjusted. The carrier 4 and the drawstrings 5 of each carrier element 53-57 are in the middle via the respective compensation device 6, a connecting element 13 (rod, linkage) and optionally (only in the support elements 55-57) the built, crossing support 58 secured together.

At the lower end of the compensation devices 6, a spacer rod 59 for measuring the position of the carrier 4 of the respective carrier element 53- 57 is provided in each case. In this case, the distance of the lower end of the length-adjustable compensating device 6 from the bottom 9 is measured directly. Together with the present length adjustment of the compensation device 6 (and the dimension of the connecting element 13 and possibly the carrier 58), this can be used to infer the current position and thus the degree of deflection of the respective carrier 4. By adjusting the length of the compensation device 6, the position of the carrier 4 under load on each carrier element 53-57 can be regulated separately (as described in detail in FIG. 1).

Fig. 2b shows the support structure of Fig. 5a at a later stage of construction. On the supports 4 of the support members 53, 54 and on the support 58 formwork supports 60 have been placed. This formwork support 60 have a slightly higher height than the adjacent support 4 of the support members 55-57 (alternatively, the height of the support 4 of the support members may be equal to the height of the formwork beams 60). On the formwork beams 60 and possibly the carriers 4 of the support elements 55-57 ceiling slabs 61 (alternatively ceiling scarf elements with upward facing skin) are arranged on which is poured in the context of concreting the floor to be created liquid concrete. In Fig. 2b, only a portion of the formwork elements 61 is shown for simplicity.

It should be noted that the formwork field, defined by the projectile columns in FIGS. 2a, 2b, typically has an edge length of approximately 7 m to 10 m. In summary, the present invention describes a compensating device for a carrier or bolt, wherein the deflection of the carrier by the compensation device is adjustable by clamping against a running behind the carrier drawstring. The drawstring is spaced from the support in the region of the compensation device, the outer ends of the drawstring engaging directly on the support. With the invention, a deflection of the carrier under its own weight and / or external load can be counteracted. Load deformations of the beams, which are caused by the concrete load and by the weight, can be compensated with the means according to the invention.

Claims

claims

A support element (1; 21; 31; 41; 53-57) for concrete formwork, comprising a support (4) for receiving external forces (10) and a drawstring (5) running behind the support (4) , and with at least one length-adjustable tensioning device, which is arranged between support (4) and drawstring (5), with which the local distance between support (4) and drawstring (5) is adjustable,

characterized,

in that the length-adjustable tensioning device is designed as a length-adjustable compensating device (6; 6a, 6b) with a motor drive for adjusting the length of the compensating device (6; 6a, 6b), in that a measuring device is provided, by which the position (x) of the

And in that a control device (12) is provided, by which the length (L) of the compensation device (6; 6a, 6b ) is controllable in dependence on the position (x) of the carrier (4).

2. carrier element (1; 21; 31; 41; 53-57) according to claim 1, characterized in that the motor drive comprises an electric drive, in particular a linear motor.

3. carrier element (1; 21; 31; 41; 53-57) according to claim 1, characterized in that the motor drive comprises a hydraulic drive or a pneumatic drive.

4. carrier element (1; 21; 31; 41; 53-57) according to one of the preceding claims, characterized in that the measuring device has a Distance rod (59) or a rope (43) with pulley (44) and ballast (45) or a laser rangefinder (11).

5. Carrier element (1; 21; 31; 41; 53-57) according to one of the preceding claims, characterized in that the

Compensation device (6; 6a, 6b) is adjustable in length in a direction which extends substantially perpendicular to the carrier (4).

6. carrier element (1; 21; 31; 41; 53-57) according to one of the preceding claims, characterized in that the carrier element (1; 21;

31; 41; 53-57) has fastening means (7a, 7b) for the carrier element (1; 21; 31; 41; 53-57) at two opposite ends of the carrier (4), in particular for attachment to projectile columns (2, 3; 51, 52 ).

7. Carrier element (1; 21; 31; 41; 53-57) according to one of the preceding claims, characterized in that the carrier (4) is designed to be telescopic.

8. support element (1; 21; 31; 41; 53-57) according to one of the preceding

Claims, characterized in that the carrier (4) fastening means for fixing a plurality of formwork supports (60) on the support (4).

9. carrier element (1; 21; 31; 41; 53-57) according to one of the preceding

Claims, characterized in that a plurality of length-adjustable compensation devices (6; 6a, 6b) are provided, which are distributed over the length of the carrier (4).

10. Carrier element (1; 21; 31; 41; 53-57) according to one of the preceding claims

Claims, characterized in that a signaling device is provided which outputs a warning signal when exceeding a limit value for the position (x) of the carrier (4), in particular a acoustic, visual or electronic warning signal.

11.Use of carrier elements (1; 21; 31; 41; 53-57) according to one of claims 1 to 10 for constructing a concrete formwork, in particular for forming a slab formwork.

12. Use of a carrier element (1; 21; 31; 41; 53-57) according to one of claims 1 to 10 for the continuous compensation of bending deformations of the carrier (4), wherein a variable external force (10) acts on the carrier (4). acts, in particular wherein the external force (10) on the support (4) is caused by the weight of concrete.