EP2372082B1 - Formwork girder - Google Patents

Description

The invention relates to a lattice girder for the expansion of tunnel-shaped structures according to the features in the preamble of claim 1.

In the construction of underground structures, support frames adapted to the breakout geometry are used, which serve to directly support the vault obtained during excavation. Subsequent expansion takes place in cast-in-situ concrete using shotcrete. The individual support frames remain within the created concrete shell.

For the support frame used lattice girders have proven that are assembled on site to a lined up in the circumferential direction of the expansion grid sheet. Compared with solid-walled carrier profiles, their advantage lies in the material and weight savings as well as in the avoidance of undesirable cavities due to the spray shadow that occurs. Thanks to the open structure of the lattice girders, they enable a homogenous construction of the concrete shell, within which they achieve a high quality of bonding and, in addition to the reinforcing steel mats used, serve as additional reinforcement.

By the disclosure of the DE 200 21 580 U1 is a lattice girder known for tunneling, which consists essentially of two upper straps and two lower straps.

To stiffen the support structure are in horizontal alignment between the two lower chords and the two upper straps cross struts. A respective lower flange is also connected to the corresponding upper flange over other truss braces.

The lattice girder, which through the DE 10 2005 006 297 A1 is shown, consists of a top flange and two bottom straps. The top chord is connected to a bottom chord via a truss stiffener. The two lower straps are in turn connected by a cross brace. This is intended to give the frame structure the necessary stability.

Furthermore, by the EP 0 073 733 A1 a lattice girder known, which consists of two upper straps and a lower chord. The connection of the three straps via a complex ausgestaltetes stiffening element, which is integrally formed from a multi-curved profile bar. The stiffening element extends both horizontally between the two upper straps and vertically between the lower flange and the two upper straps.

The DE 197 11 627 C2 discloses a lattice girder removal frame for tunneling which is composed of individual lattice girders. The individual lattice girders each have a top chord and two bottom chords which each extend in the longitudinal direction of the lattice girder and in whose cross section the vertices of a triangle form one another. The upper chord is connected to the individual lower chords via meandering truss struts. The lattice girder additionally has transverse webs running obliquely to its longitudinal direction, which serve to stiffen the limbs of the triangular lattice girder formed by the framework struts. The transverse webs are for this purpose on the two lower chords and are connected to these.

The DE 198 35 557 A1 discloses a lattice girder without crossbars, but which is stackable.

The basic structure of the lattice girder has proven itself in practice. The triangular shape of the lattice girders closed by the truss struts and the crossbars However, claims a correspondingly high volume. Against the background of economical storage and the necessary transport, the geometry leaves room for improvement, in particular for the space-saving stackability of the individual lattice girders.

The invention is therefore an object of the invention to improve a lattice girder for the expansion tunnel-shaped structures to the effect that this allows a space-saving stackability without loss of its static load capacity at approximately constant material usage and thus the density of the stacked lattice girder can be increased.

The solution to this problem consists according to the invention in a lattice girder with the features of claim 1.

Following the inventive concept, the individual transverse webs each extend between two truss struts and are arranged at a corresponding distance from the upper flange and at a distance from the lower chords. Even if the individual transverse webs may have various configurations continuously or occasionally, for example bent, canted, as well as individual formations, cross-sectional jumps and combinations of the above, these have a straight course between the truss struts. The particular advantage lies in the contactless spacing of the transverse webs of the individual straps, whereby the triangular shape formed in the cross section of the lattice girder is reduced. This is achieved by shifting the individual transverse webs as the base of the triangle away from the lower belts and thus towards the upper belt. This results in a free space which extends between the lower chords to below the transverse webs. The cross section of the lattice girder formed by the truss struts and the transverse webs thus substantially resembles an A-shape. According to the invention, the distance to the upper flange and the distance to the lower chords have a ratio of 1: 2 to 1: 6 to each other. In an arrangement of the transverse webs within the indicated range, an economic ratio of the bending stiffness of the truss struts achieved by the transverse webs results in the clearance between the lower belts.

In the necessary for the transport or storage stacks of lattice girders dive this each with their upper flange and a portion of the truss struts in the obtained space, thereby reducing the stack height. The legs of the lattice girder formed from the truss struts are still stiffened over the transverse webs. The remaining unsupported lever arm of the truss struts is determined by the position of the transverse webs between the upper flange and the lower chords.

As remaining in the reinforced concrete shell reinforcement, the lattice girders are made of metal. The lower chords and the upper chord are welded to the truss struts connecting them. The opposite in the transverse direction of the lattice truss trusses are also connected to the transverse webs connecting them by welding. Advantageously, the individual connections are made in economic point resistance welding.

Both the upper and lower chords may have various cross-sectional shapes, such as square, rectangular, and oval, or combinations of the foregoing. Advantageously, these are circular, to allow easy production. In principle, the lateral surface of the individual straps can also be given a structure, such as, for example, ribbed or profiled reinforcing steel. This increases the composite effect of the lattice girder with the concrete surrounding it.

Advantageous developments of the inventive concept are the subject of the dependent claims 2 to 10.

The individual transverse webs are in each case connected via end-side bends with the truss struts lying opposite one another in the transverse direction of the lattice girder. The bends increase the contact area between the transverse webs and the truss struts, thereby achieving a sufficient weld seam length.

The end-side developments of the transverse webs are arranged axially parallel to the truss struts. This results in the largest possible contact area between the truss struts and the bends.

Advantageously, the bends of the transverse webs to the lower chords of the lattice girder are aligned. Alignment causes a positive shift in the center of gravity of the welds. As a result, the stiffening effect is increased in the same position of the transverse webs to the upper and lower straps by the lever arm is shortened at a bending stress of the truss braces.

Furthermore, the invention provides that the truss struts are each formed in a side view of the lattice girder of a V-shaped bent rod with angled at its respective ends and thereby pointing away from each other foot sections. The tip of the V-shaped bent rod is rounded here and welded to the upper flange.

The position of the truss braces is chosen so that the tip does not protrude beyond the upper flange. In this way, a hook-free sliding example of welded steel mesh along the upper belt is achieved. The angled to individual foot sections ends of the rod are welded to one of the lower chords. The individual truss struts each form a static triangle with the lower chord. In addition to the spacing of the upper belt to the individual lower chords, the truss struts thus serve for transverse force absorption and in combination with the transverse webs for spatial reinforcement of the lattice girder. As a result, a viable stiffening of the vault is already achieved at the beginning of installation.

Furthermore, the transverse webs are arranged in a side view of the lattice girder toward the side of the foot sections towards the V-shaped bent rod of the truss struts. In addition to the manufacturing simplification, in particular the bending stiffness of the truss struts in the longitudinal direction of the lattice girder is thereby additionally increased by the material doubling.

The angled foot portions of the truss braces are arranged perpendicular to an exciting between the axes of the lower chords level on the lower chords. Thus, the two foot portions of a V-shaped bent rod of the truss struts on one of the lower chords. Here are the run Foot sections each axis parallel to the lower chords. This results in a maximum contact surface between the foot sections and the lower chords, which are connected to each other by welding. In addition, no disturbing projections protrude beyond the lower chords, whereby a simple and hook-free smoothing of the shotcrete is made possible.

In addition, the invention provides that the lattice girder according to the invention has armature plates arranged at its respective ends. About this, the individual lattice girders can be strung together in the circumferential direction of the expansion to obtain a the outbreak of the vault stiffening grid sheet. The individual lattice girders are adapted for this purpose in their longitudinal formation of the outbreak mold.

According to the invention, the anchor plates each have two isosceles angular plates, which are arranged in a V-shape to each other. The V-shaped arrangement of the angle plates corresponds essentially to the triangular cross-sectional shape of the lattice girder, wherein the individual legs of the angle plates each extend in the longitudinal direction and transverse direction of the lattice girder. About the longitudinal legs of the angle plates are welded to the lattice girder, while the transverse legs form a corresponding contact surface to adjacent lattice girders. This results in spite of low material usage a manufacturing technology favorable and statically sufficiently rigid node between the individual lattice girders.

The angle plates of the anchor plates each connect the upper flange of the lattice girder with its lower chords, wherein the transversely to the longitudinal direction of the lattice girder arranged legs of the angle plates have these passing through openings. The overlapping openings of the armature plates of adjacent lattice girders within the lattice arch serve to receive rod-shaped connecting means, which enable a site-specific coupling of the individual lattice girders to one another as a detachable or non-detachable connection.

The invention creates a lightweight and, through its open design, space-saving stackable lattice girder for the expansion tunnel-shaped structures. Due to the displacement of the stiffening transverse webs of the closed body of the lattice girder is reduced while maintaining its individual cross-sections, so that in contrast to the usual construction can be stacked up to twice the other lattice girder volume. Consequently, the costs incurred are halved.

The truss braces, which do not project beyond the triangular cross-sectional shape of the lattice girder, as well as transverse webs permit a smooth outer contour of the lattice girder, which offers significant advantages in particular when laying concrete steel mats to be conveyed past the lattice girders. Otherwise protruding components regularly lead to the hooking of the individual meshes of the welded mesh. As a result, a clean and hook-free stripping of the applied shotcrete is possible.

Figur 1

einen typischen Aufbau eines Gitterträgers aus dem Stand der Technik in einem Querschnitt;

Figur 2

einen erfindungsgemäßen Gitterträger in Darstellungsweise von Figur 1;

Figur 3

zwei aufeinander gestapelte Gitterträger gemäß dem Stand der Technik in einer perspektivischen Ansicht als Teilausschnitt;

Figur 4

zwei aufeinander gestapelte erfindungsgemäße Gitterträger gemäß der Darstellungsweise von Figur 3 sowie

Figur 5

den erfindungsgemäßen Gitterträger in einer perspektivischen Gesamtansicht.

The invention is explained in more detail with reference to a schematic embodiment shown in the drawings. Show it:

FIG. 1

a typical structure of a lattice girder of the prior art in a cross section;

FIG. 2

a lattice girder according to the invention in the representation of FIG. 1 ;

FIG. 3

two stacked lattice girders according to the prior art in a perspective view as a partial section;

FIG. 4

two stacked lattice girders according to the invention as shown in FIG FIG. 3 such as

FIG. 5

the lattice girder according to the invention in a perspective overall view.

FIG. 1 illustrates the structure of a known from the prior art typical lattice girder 1 in cross section.

The lattice girder 1 has a top flange 2 and two bottom straps 3, which form the vertices of a triangle to each other. The upper flange 2 is connected in each case via truss struts 4 with the two lower chords 3. On the lower chords 3 are in the transverse direction of the lattice girder 1 connecting transverse webs 5. The triangular shape of the lattice girder 1, which is closed by the truss braces 4 and the transverse webs 5, in particular includes a large cross-sectional volume of the lattice girder 1 due to the position of the transverse webs 5 on the lower girders 3.

FIG. 2 shows a lattice girder 1a according to the invention, which also has a top flange 2a and two bottom straps 3a, wherein the top flange 2a is connected in each case via truss braces 4a with the bottom straps 3a. In the upper third of the lattice girder 1a to the top flange 2a, the transverse webs 5a connecting in the transverse direction of the lattice girder 1a opposite truss struts 4a are arranged. The truss struts 4a connecting portion of the transverse webs 5a in this case runs parallel to an exciting between the lower chords 3a level. The respective end regions of the transverse webs 5a have angled portions 50a which are angled away from the lower webs 3a of the lattice girder 1a. Compared to the truss struts 4 a, the angled portions 50 a of the transverse webs 5 a run parallel to the axis with their respective longitudinal axes being superimposed in the present cross-sectional view.

A longitudinal axis of the transverse webs 5a together with the longitudinal axis of one of the truss struts 4a a common intersection point X. In the direction of a perpendicular bisector to an exciting between the longitudinal axes of the lower chords 3a base of the triangle, the intersection point X has a distance A to the longitudinal axis of the upper flange 2a. Opposite a longitudinal axis of one of the lower chords 3a, the intersection point X is spaced at a distance B in the direction of the mid-perpendicular to the base of the triangle. The ratio of distance A to distance B is 1: 4.

By the opposite to the in FIG. 1 shown lattice girder 1 to the top flange 2a displaced transverse webs 5a, the lattice girder 1a a clearance C, which by the truss braces 4a and the transverse webs 5a and between the Lower chords 3a exciting level is limited. Thus, the cross section of the lattice girder 1a corresponds to a substantially A-shaped configuration.

FIG. 3 illustrates the high space requirements when stacking the in FIG. 1 Since this has a closed between the lower chords 3 on the transverse webs 5 triangular shape, the lattice girder 1 can not be stacked with another lattice girder 1 in each other, so that the transverse webs 5 when stacking each on the top flange 2 of the underlying lattice girder. 1 rest.

In contrast clarifies FIG. 4 the stacked arrangement of the lattice girder 1a according to the invention, wherein the lower lattice girder 1a with its upper flange 2a and parts of the truss struts 4a immersed in the free space C of the stacked lattice girder 1a. The transverse webs 5a of the upper lattice girder 1a in this case are also on the upper flange 2a of the lower lattice girder 1a. By located at a distance B to the lower chords 3a position of the transverse webs 5a of the upper flange 2a of the lower lattice girder 1a extends relative to the in FIG. 3 shown lattice girder 1 clearly closer to the top flange 2a of the overlying lattice girder 1a.

In this view, it can be seen that the truss braces 4a are each formed from a V-shaped bent rod, the tip points towards the top flange 2a. The respective end portions of the rod are angled away from each other wegweisenden foot sections 40a, which extend axially parallel to the lower chords 3a. The foot portions 40a are hereby arranged perpendicular to a tensioning between the longitudinal axes of the lower chords 3a level on the lower chords 3a, which in particular FIG. 2 clarified in cross-section.

The in FIG. 5 shown in a perspective overall view lattice girder 1b corresponds in its cross-section already in the Figures 2 and 4 shown lattice girder 1a. An upper flange 2b and two lower straps 3b spaced therefrom extend parallel to one another in the longitudinal direction of the lattice girder 1b. The lattice girder 1b has a curvature which runs around a transverse axis parallel to a plane which is exciting between the lower girders 3b. At The respective ends 6, 7 of the lattice girder 1b anchor plates 8 are arranged, which extend on both sides of the triangular lattice girder 1b in each case in a plane between the upper flange 2b and one of the lower chords 3b in the form of angle plates 9. The opposite in the transverse direction of the lattice girder 1b angle plates 9 thus have a V-shape to each other. In this case, the angle plates 9 each connect the upper flange 2b to one of the lower chords 3b via legs 10 aligned in the longitudinal direction of the lattice girder 1b. The legs 11 of the angle plates 9 extending in the transverse direction of the lattice girder 1b have openings 12 passing through them.

For the storage and transport of the lattice girder 1b this is stacked with other lattice girders according to the invention on each other, wherein the clearance C respectively serves to receive the triangular cross-section of an underlying lattice girder 1b. In this case, the lattice girder 1b can exchange with its upper girth 2b into the free space C of the lattice girder 1b above it, until the upper girder 2b bears against the transverse webs 5b. By the circumference, without projections of the truss struts 4b and transverse webs 5b trained cross-sectional shape of the lattice girder 1 necessary for the expansion of welded mesh can smoothly slide along, and rest on the outer circumference of the upper belt 2b and the lower chords 3b.

At their place of use, the lattice girders 1 b are connected via their respective anchor plates 8 with adjacent lattice girders or other components to a support frame or grid arch. For this purpose, detachable or non-detachable connection means are inserted into the openings 12 of the legs 11 in order to obtain a rigid connection point between the lattice girder 1b and the adjacent lattice girders or components.

Even when smoothing the concrete shell formed by shotcrete occur no disturbing projections of the lattice girder 1b in the workspace of the smoothing tool.

The position of the transverse webs 5b ensures sufficient stiffening of the opposite truss struts 4b, so that their usual cross-section is maintained. Due to the significantly narrower stackability of the lattice girder 1b can be compared to the prior art stored up to twice the usual amounts and transported, thereby halving the respective costs. In addition, the design of the lattice girder 1b according to the invention comes from without additional use of material.

Reference numerals:

1 -

Lattice girder (prior art)

1a -

girder

1b -

girder

2 -

Upper strap of 1

2a -

Upper strap of 1a

2 B -

Upper strap of 1b

3 -

Bottom strap of 1

3a -

Bottom strap of 1a

3b -

Bottom strap of 1b

4 -

Truss brace from 1

4a -

Truss brace from 1a

4b -

Truss brace from 1b

5 -

Crosspiece of 1

5a -

Crossbar of 1a

5b -

Crossbar of 1b

6 -

End of 1b

7 -

End of 1b

8th -

Anchor plate of 1b

9 -

Angle plate from 1b

10 -

Thighs of 9

11 -

Thighs of 9

12 -

Opening in 11

40a -

Foot sections of 4a

40b -

Foot sections of 4b

50a -

Angling from 5a

50b -

Angling from 5b

A -

Distance between 2a and X

B -

Distance between 3a and X

C -

free space

X -

Intersection between 4a and 5a

Claims (10)

1. Lattice girder for the development of tunnel-shaped constructions, which has an upper truss (2a, 2b) and two lower trusses (3a, 3b), which in each case extend in the longitudinal direction of the lattice girder (1a, 1b) and, in the cross-section thereof, form the corner points of a triangle to each other, wherein, furthermore, the lattice girder (1a, 1b) has cross-members (5a, 5b) and the upper truss (2a, 2b) is in each case connected by means of framework struts (4a, 4b) to the lower trusses (3a, 3b), wherein the cross-members (5a, 5b) in each case extend between two framework struts (4a, 4b) and are arranged with a spacing (A) from the upper truss (2a, 2b) and the cross-members (5a, 5b) are arranged with a spacing (B) from the lower trusses (3a, 3b), characterised in that the spacing (A) and the spacing (B) have a ratio of 1 : 2 to 1 : 6 to each other, wherein a free space (C) is spanned by the framework struts (4a, 4b) and the cross-members (5a, 5b), so that at least one upper truss (2a, 2b) of a second lattice girder (1a, b) can protrude into the free space (C) for transport or storage.
2. Lattice girder according to claim 1, characterised in that the cross-members (5a, 5b) are in each case connected by means of bent end portions (50a, 50b) to the framework struts (4a, 4b).
3. Lattice girder according to claim 2, characterised in that the bent portions (50a, 50b) are arranged axially parallel to the framework struts (4a, 4b).
4. Lattice girder according to claim 2 or 3, characterised in that the bent portions (50a, 50b) are oriented towards the lower trusses (3a, 3b).
5. Lattice girder according to one of claims 1 to 4, characterised in that in a side view of the lattice girder (1a, 1b) the framework struts (4a, 4b) are in each case formed by a rod bent in a V shape with foot portions (40a, 40b) which are bent at the ends and are directed away from one another.
6. Lattice girder according to claim 5, characterised in that in a side view of the lattice girder (1a, 1b) the cross-members (5a, 5b) are in each case arranged to the side of the foot portions (40a, 40b) on the V-shaped bent rod of the framework struts (4a, 4b).
7. Lattice girder according to claim 5 or 6, characterised in that the foot portions (40a, 40b) are arranged on the lower trusses (3a, 3b) perpendicular to a plane spanning between the axes of the lower trusses (3a, 3b) and axially parallel with respect to the lower trusses.
8. Lattice girder according to one of claims 1 to 7, characterised by anchor plates (8) arranged on the respective ends thereof.
9. Lattice girder according to claim 8, characterised in that the anchor plates (8) in each case have two equilateral angle brackets (9) which are arranged in a V shape with respect to one another.
10. Lattice girder according to claim 9, characterised in that the angle brackets (9) in each case connect the upper truss (2a, 2b) to the lower trusses (3a, 3b), wherein the flanks (10) of the angle brackets (9) arranged transversely with respect to the longitudinal direction of the lattice girder (1a, 1b) have openings (12) which pass through the angle brackets.

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