EP1528173B1 - Prestressed floor with hollow floor slabs - Google Patents

Abstract

The method for the manufacture of a prestressed flat slab floor (1) involves the laying of a number of cored floor slabs (2,3) in a X-Y modular grid. The one side of the cored floor slabs in each case is integrated in a prestressed girder section (4,5) manufactured from in-situ concrete. The unstressed reinforced cored floor slabs has an additional prestressed reinforcement extending in the vertical direction. For the prestressed reinforcement a tensioning cable is laid in the gap (32) between the abutting cored floor slabs. An independent claim is included for a prestressed flat slab floor with cored floor slabs laid in a X-Y modular grid.

Description

The invention relates to a prestressed flat ceiling with hollow ceiling slabs and a method for the production thereof according to the preamble of patent claims 1 and 4, respectively.

A prestressed concrete flat cover according to the preamble of claim 1 and 4 is with the DE-U-20 215 502 , as well as the US-A-4,443,985 known.

For the production of a flat ceiling is at the CH-A-535 878 mounted on the free upper ends of vertical supports a flat, undistorted and level Schalboden. Depending on the static requirements, reinforcing rods are placed on this formwork floor. Additional tensioning cables are introduced in the vicinity of the supporting supports of the reinforcing bars, which are prestressed after pouring out the formwork floor and hardening the concrete mass.

It is therefore a monolithic concrete floor, the load capacity is improved by the introduction of tensioning cables. Disadvantage of this known technique is that a very high basis weight must be taken into account. Accordingly, high support loads are given with correspondingly large-dimensioned supports.

Due to the high weight per unit area, correspondingly high ceiling cross sections must be produced to ensure stability. However, this involves high manufacturing costs. The manufacturing cost of such a building are therefore high.

In addition, there is the disadvantage that there is no possibility to install installations and / or insulation in the interior of such a ceiling.

With the subject of DE 201 03 059 U1 a hollow ceiling slab has become known which consists of a lower and a spaced above upper shell, wherein the shells are interconnected by lattice girders. Although there is the possibility in the interior installations and insulating material, but it is not shown how such a hollow ceiling panel in flat roof systems after CH-A-535 878 could be moved.

The invention is therefore the object of a prestressed flat ceiling after the DE-U-20 215 502 , as well as the US-A-4,443,985 educate so that they can be manufactured with significantly low basis weight and lower production costs.

To achieve the object, the invention is characterized by the features of claims 1 and 4.

With the given technical teaching has the advantage that now very slender dimensioned hollow ceiling panels can be used with low basis weight, because their static load capacity in combination with prestressed belt strips - in which they are involved - is achieved.

It can therefore be used very cost-effective and only a small height requiring hollow ceiling panels, which are interconnected only in the narrow region of a belt strip with a higher-quality in-situ concrete.

This results in significant advantages:

The hollow ceiling panels are overall more cost effective than poured finished ceiling elements and have a much lower basis weight.

The ceiling system according to the invention is about 50% lighter than monolithically produced ceilings. Such monolithically produced ceilings consist for example of precast ceilings, which are poured out at the construction site with appropriate in-situ concrete.

A conventional prefabricated ceiling system of a length of, for example, 8 x 8 meters requires an in-situ concrete quantity of about 19 m ^{3 to} produce the precast ceiling element, which in the final state has a thickness of, for example, 30 cm.

This is where the invention, which provides, based on an area of 8 x 8 m only to use a relatively thin hollow ceiling slab with a thickness of 2 x 7 cm, which preferably consists of two spaced-apart shells, these shells only from an inferior Concrete, such as grade B25 exist.

Such a lightweight and low-building hollow ceiling slab is connected with its narrow side with the respective adjoining hollow ceiling slab on cast in-situ concrete belt strips.

To produce the belt strip, a higher-grade in-situ concrete, for example in grade B80, is used and prestressed with the tensioning cables according to the invention so as to distribute the bearing forces in one direction.

Regarding the previously mentioned amount of 19 m ³ in situ concrete in the production of a conventional precast ceiling, the ceiling system according to the invention requires only for the production of the belt strip a higher quality concrete, eg grade B80, with an amount of only 2.1 m ² .

The ceiling system is also applicable as a multi-field carrier.

According to the invention, the upper shell of the respective hollow ceiling panel is shortened in the belt strip area, so that there results a larger recessed area. There can therefore be achieved by in-situ concrete supplements a flow property of the upper shell. It is therefore a completely continuous, jointless and provided without joists and falls flat ceiling.

Another advantage of the invention is that, because of the use of hollow ceiling slabs, it is now possible for the first time to introduce installations and insulating material into the flat slab over completely continuous ceiling lengths and widths.

With the given technical teaching there is the advantage that one can create large-area ceiling systems with the flat ceiling according to the invention, which are particularly useful for commercial buildings, office buildings, apartment buildings and the like. With much lower basis weight and lower production costs can be spanned very large ranges. It can thus grid systems of up to 12 to 12 meters can be achieved, which was possible in the prior art only with much higher basis weights and heights.

It is also a quick transport and installation of low-building and low-weight hollow ceiling slabs on the job site possible. The necessary construction work refers to the pouring of in-situ concrete to form the relatively narrow belt strips, for example, 40 cm wide. It does not require large-scale concreting and the associated large-scale Schalund support work more.

Where previously large formwork panels had to be installed with appropriate support beams, it is now sufficient to shed the in-situ concrete only in the area of the narrow belt strips.

The above-mentioned inventive teaching is that the load transfer of the flat ceiling with hollow ceiling slabs on the prestressed belt strips in situ concrete and on the laid perpendicular slack reinforced hollow ceiling panels. This formulation applies to standard ceilings with a column grid of Ix, Iy up to about 10.0m.

Following an extension of this technical teaching, it is envisaged that both the smaller spans and the larger spans will also be covered:

For belt stiffeners with a wingspan of 5 - 7 [m], the load-bearing resistance can be ensured even with a fl exible reinforcement. Preloading is required only from a span of I> 8 m and absolutely necessary from a span of I> 10.0. The hollow ceiling slabs with the slack reinforcement already inserted in the precast plant have a range of application of up to approx. 8m span. If larger spans than 8m are to be overcome in this direction, the slack reinforced hollow slabs are supplemented by a prestressing reinforcement. It uses the joint between the individual slats, within the local a tensioning cable is inserted.

These tension cables intersect the belt strip of in-situ concrete and lead over several fields. In contrast to the arranged in the belt strips of in-situ concrete, concentrated bias is called the regularly spaced in the joints clamping cable as a distributed bias.

Due to different span ratios, any combinations of "limp-reinforced" and "prestressed reinforced" are possible. From the execution is possible a short span for the belt strip and a large span for the hollow ceiling slab and vice versa. Accordingly, the short span would be limp reinforced and executed the large span prestressed.

In the following the invention will be explained in more detail with reference to drawings showing only one embodiment. Here are from the drawings and their description further features essential to the invention and advantages of the invention.

Figur 1:

schematisiert die Draufsicht auf eine Flachdecke nach der Erfindung;

Figur 2:

ein Schnitt durch die Flachdecke nach Figur 1 gemäß der Linie A-A;

Figur 3:

ein vergrößerter Schnitt durch den Anschluss von zwei Hohldeckenplatten im Bereich eines Gurtstreifens bei Herstellung eines Gurtstreifens;

Figur 4:

der Schnitt ähnlich wie Figur 3 vor Herstellung des Gurtstreifens;

Figur 5:

vergrößert ein Schnitt durch ein Hüllrohr mit daran angeordneten Spannkabeln;

Figur 6:

ein vergrößerter Schnitt nach Figur 2 mit Darstellung weiterer Einzelheiten;

Figur 7:

eine weitere Vergrößerung der Darstellung nach Figur 6;

Figur 8:

ein Schnitt gemäß der Linie VIII-VIII in Figur 6;

Figur 9:

Schnitt durch ein weiteres Ausführungsbeispiel einer Flachdecke mit Spannbeton-Hohlplatten;

Figur 10:

Schnitt gemäß der Linie A-A in Figur 9.

Figur 11:

Draufsicht auf eine weitere Ausführung der Flachdecke mit Vorspannung in den Fugen zwischen den Hohldeckenplatten

Figur 12:

Schnitt B-B in Figur 11

Figur 13:

Detail Y aus Figur 12 - Darstellung eines Hüllrohres im Schnitt

Figur 14:

Tabelle mit Darstellung der Kombination unterschiedlicher Bewehrungsarten

Show it:

FIG. 1:

schematizes the plan view of a flat ceiling according to the invention;

FIG. 2:

a section through the flat ceiling after FIG. 1 according to the line AA;

FIG. 3:

an enlarged section through the connection of two hollow ceiling panels in the region of a belt strip in the manufacture of a belt strip;

FIG. 4:

the cut is similar to FIG. 3 before production of the belt strip;

FIG. 5:

enlarges a section through a cladding tube with tensioning cables arranged thereon;

FIG. 6:

an enlarged section after FIG. 2 with further details;

FIG. 7:

a further enlargement of the representation after FIG. 6 ;

FIG. 8:

a section according to the line VIII-VIII in FIG. 6 ;

FIG. 9:

Section through another embodiment of a flat ceiling with prestressed concrete hollow slabs;

FIG. 10:

Section along the line AA in FIG. 9 ,

FIG. 11:

Top view of another embodiment of the flat ceiling with prestress in the joints between the hollow ceiling panels

FIG. 12:

Cut BB in FIG. 11

FIG. 13:

Detail Y off FIG. 12 - Representation of a cladding tube in section

FIG. 14:

Table showing the combination of different reinforcement types

According to the FIGS. 1 and 2 consists of the flat ceiling 1 from laid in the XY grid hollow ceiling panels 2, 3, each abutting one another on the longitudinal side. They form longitudinally a joint area 32, which is closed on site.

On the front side, the hollow ceiling panels 2, 3 continuing in the X direction are connected to one another via belt strips 4, 5. The belt strips 4, 5 are made of in-situ concrete at the construction site.

In the area of the belt strips, supports 6 are arranged at a mutual distance.

In the space between the adjoining hollow ceiling slabs 2, 3 are based on the FIGS. 6 and 7 Reinforcement baskets 18, 23 to be described in more detail and with corresponding, in FIG. 4 shown, ducts 8 and arranged therein tensioning cables 9 connected.

The reinforcement plant produced in this way is made according to FIG. 3 potted with in-situ concrete, wherein on the underside of the adjoining hollow ceiling slabs 2, 3, a switching table 7 is applied.

The gap is then poured in a conventional manner with in-situ concrete, so that the representation after FIG. 3 results.

The FIG. 5 shows that the laid in the belt strip 4, 5 clamping devices consist essentially of cladding tubes 8, which are arranged in a grid-shaped mutual spacing, each cladding tube consists of a plastic or sheet metal shell and in the interior one or more tensioning cable 9 are arranged.

These tensioning cables 9 may be made of a cable-shaped metal or a plastic material. It is also possible to use (multicore) stranded cables.

From the FIGS. 6 and 7 go further details of the structure of the respective belt strip 4, 5.

First, each hollow ceiling slab 2, 3 consists of a lower shell 10 made of concrete. In the lower shell 10 reinforcing bars or mats are arranged in a conventional manner.

The reinforcing bars are in the form of spaced apart reinforcing bars 11 repeatedly led out of the material of the lower shell 10 and reach the area of the respective belt strip 4, 5, according to FIG. 7 ,

The end 12 of the respective reinforcing bar 11 engages in the free space, which later forms the belt strip 4, 5.

In the same way, the upper shell 13 is formed, which in turn each has a plurality of reinforcing bars 14, which also extend in the X direction and the free ends 15 in turn engage in the intermediate space, which later forms the belt strips 4, 5.

The space between the lower and the upper shell 10, 13 of the respective hollow ceiling slab 2, 3 is filled, for example, with an insulating material 16.

The FIG. 6 indicates that in the space lattice girder 17 are arranged, which are cast with their upper and lower ends in the respective shells 10, 13 in order to ensure a static surface load capacity.

It is now important that each belt strip 4, 5 is filled by one or more reinforcement cages 18, 23. Instead of the two reinforcement cages 18, 23 shown here, only a single reinforcing cage may be present.

Each reinforcement cage 18, 23 consists of a grid mesh which extends along the entire length of the respective belt strip 4, 5 and which is spent as a loose part to the site. There it is inserted into the space between the abutting hollow ceiling panels 2, 3.

The outer reinforcement cage 18 consists of a plurality of mutually spaced U-shaped bars 19, which are connected in the X direction by longitudinal bars.

Each U-bar 19 consists of an upper horizontal leg 20, which merges into a vertical leg 21, which in turn merges into a lower horizontal base leg 22.

The U-bar 19 is exactly mirror-symmetrical with respect to a longitudinal center line, so that the outer reinforcement cage 18, the two end faces of the hollow ceiling panels 2 and the protruding ends 12, 15 of the reinforcing bars 11, 14 interconnects.

Similarly, a smaller, inner reinforcement cage 23 is provided, which in turn consists of a plurality of mutually parallel spaced U-rods.

Each U-bar has an upper horizontal leg 24, which merges into a vertical leg 25 and this in a horizontal leg 26.

The said reinforcement cages 18, 23 with their bars are connected to one another via corresponding longitudinal bars 27.

There is still an upper, horizontally extending connecting rod 28 is present, which connects the ends 15 of the upper reinforcing bars 13 together.

In addition to the lower longitudinal bars 27 and upper longitudinal bars 29 are present.

The FIG. 8 schematically shows the arrangement of the clamping device, as shown by FIG. 4 was explained. It consists of the parabolic laid ducts 8 with the tensioning cables 9 arranged therein, as shown in FIG FIG. 5 is shown.

The respective cladding tube 8 is connected via cable holder 31 with the respective associated reinforcement cage 18, 23. It is waved in the direction of its longitudinal extension or parabolic, as is in FIG. 8 is shown.

After the concrete in the belt strip 4, 5 is poured out and cured, a bias with a tensioning device not shown on the free ends of the ducts 8 with the tensioning cables 9 arranged therein in the opposite directions of arrow 30. The tensioning device is after a certain time of Preload application removed again.

In this way, it is possible to initiate the support forces, which extend in the flat ceiling in both the X and Y directions, only in the Y direction on the narrow belt strips 4, 5, while in the X direction, the carrying capacity of the hollow ceiling slab. 2 assumes the carrying capacity with reinforcement bars arranged therein.

In the FIGS. 9 and 10 is shown as a further embodiment, a flat ceiling with prestressed concrete hollow slabs.

A prestressed concrete hollow slab consists of two spaced-apart flat slabs with a thickness of approximately 6 to 8 cm each and connecting webs forming intervening cavities. The section along the line AA in FIG. 9 is a section through a cavity, so that outside of this cavity, the connecting webs 35 (see also FIG. 12 ) between the upper plate shell and the lower plate shell.

Also, such a prestressed concrete hollow plate is connected in the manner previously described with the high-strength prestressed in-situ concrete strip.

In the embodiment of the FIGS. 11-14 is the above-mentioned clamping concept described.

The FIG. 11 shows that in addition to the bias in the main direction (in FIG. 11 in the horizontal direction-arrow 33) also a perpendicular thereto extending bias in the secondary direction (in FIG. 11 in the vertical direction - arrow direction 34) is made.

For the application of the bias in the secondary direction (arrow 34), the same means and measures are used, as described above for the bias in the main direction (arrow 33). Therefore, the same reference numerals apply to the same parts.

The hollow ceiling slabs 2, 3 with the already deployed in the precast plant flaccid reinforcement have a range of up to approx. 8m span. If larger spans than 8 m are to be overcome in this direction, then the slack reinforced hollow ceiling slabs 2, 3 are supplemented by a prestressing reinforcement. In this case, one uses the joint 32 between the individual plate strips within which a tensioning cable, consisting of a cladding tube 9 with steel cables 9 inserted there, can be inserted. This is in FIG. 12 shown, where FIG. 13 it can be seen how the steel cable inserted in the joint area is constructed on average. It consists of a cladding tube 8, which encloses a number of tensioning cables 9.

Out FIG. 11 again, it can be seen that the tensioning cables 8, 9 running in the direction of the arrows 34 and inserted in the joint regions 32 intersect the belt strips 4, 5 of in-situ concrete and lead over several fields of the hollow ceiling slabs 2, 3.

In contrast to the arranged in the belt strips 4, 5 of in-situ concrete, concentrated bias is called the regularly spaced in the joints 32 and in the direction of arrow 34 extending tensioning cable 8, 9 as a distributed bias.

The table in FIG. 14 gives an overview of the possible type of reinforcement at different spans. Due to different span ratios, all combinations are limp-reinforced and prestressed possible. From the execution is possible a short span for the belt strip 4, 5 and a large span for the hollow ceiling slab and vice versa. Accordingly, the short span would be limp reinforced and executed the large span prestressed.

drawing Legend

1

flat ceiling

2

Hollow ceiling panel

3

Hollow ceiling panel

4

Belt strips (made of in-situ concrete)

5

belt strips

6

support

7

formwork table

8th

cladding tube

9

span cable

10

Lower shell

11

rebar

12

The End

13

Upper shell

14

rebar

15

The End

16

insulation

17

girder

18

Reinforcement cage (outside)

19

U-bar

20

leg

21

leg

22

base leg

23

Reinforcement cage (inside)

24

leg

25

leg

26

base leg

27

longitudinal bars

28

connecting rod

29

longitudinal bars

30

arrow

31

cable holder

32

joint area

33

Bias direction (main area

34

Bias direction (secondary area)

35

connecting web

Claims (7)

1. Method for producing a prestressed flat floor (1) with floor slabs (2, 3), in which, applied to the free upper ends of vertical supports (6) is a table form (7), on which reinforcement steels (11, 14, 18, 23, 27, 28, 29) are introduced and tensioning cables (9) are introduced close to the support bearings and are prestressed after the casting of the shell base and hardening of the concrete mass, a large number of hollow floor slabs (2, 3) being laid with a lower (10) and an upper shell (13) in an X-Y grid, and, in each case, the sides of the hollow floor slabs being incorporated in a prestressed girder section (4, 5) made of in-situ concrete, and wherein the hollow floor slabs (2, 3) are laid abutting one another with their longitudinal sides in the Y-direction (33) and the narrow sides directed in the X-direction (34) are in each case incorporated in the girder sections (4, 5), characterised in that an additional prestressed reinforcement running in the vertical X-direction (34) is associated with the hollow floor slabs (2, 3) which are loosely reinforced in the Y-direction (33) and a respective tensioning cable (9) is inserted into the joint (32) between the mutually abutting hollow floor slabs (2, 3) for prestressed reinforcement, and in that the tensioning cables (9) cross the girder sections (4, 5) made of in-situ concrete and lead over a plurality of areas of the hollow floor slabs (2, 3), and in that the upper shell (13) of the respective hollow floor slab (2, 3) is shortened in the girder section region (4, 5) so a larger recessed region is produced there, which is supplemented by in-situ concrete.
2. Method according to claim 1, characterised in that a high-grade concrete, for example of quality class B80, is used to produce the in-situ concrete girder (4, 5), and in that a low-grade concrete, for example of quality class B25 is used for the shells (10, 13) of the hollow floor slabs (2, 3).
3. Method according to either of claims 1 or 2, characterised in that reinforcement cages (18, 32), which are connected to the tensioning cables (9), are introduced in the intermediate space between the mutually abutting hollow floor slabs (2, 3).
4. Prestressed flat floor, produced by the method according to any one of claims 1 to 3, wherein the prestressed flat floor consists of hollow floor slabs (2, 3), which are laid in an X-Y grid and are incorporated in the region of one side in a girder section (4, 5) made of in-situ concrete, the girder sections (4, 5) being prestressed in the Y-direction (33) of their longitudinal extent, characterised in that introduced perpendicular to the prestressed girder sections (4, 5) is an additional prestressing in the X-direction (34), which takes place by means of tensioning cables (9), which are inserted between the joints (32) of mutually abutting hollow floor slabs (2, 3), and in that the tensioning cables (9) cross the girder sections (4, 5) made of in-situ concrete and lead over a plurality of areas of the hollow floor slabs (2, 3), and in that the upper shell (13) of the respective hollow floor slab (2, 3) is shortened in the girder section region (4, 5) so a larger recessed region is produced there, which is supplemented by in-situ concrete.
5. Prestressed flat floor according to claim 4, characterised in that installations and/or insulating material is introduced into the intermediate space of the hollow floor slab (2, 3).
6. Prestressed flat floor according to either of claims 4 or 5, characterised in that reinforcement cages (18, 32), which are connected to a tensioning device, are arranged in the intermediate space between the mutually abutting hollow floor slabs (2, 3).
7. Prestressed flat floor according to claim 6, characterised in that the tensioning device consists of tensioning cables (9) arranged in sheathing tubes (8), which tensioning cables are laid in an undulating manner in the direction of their longitudinal extent and are connected point-wise to bars of the reinforcement cages (18, 23) arranged parallel to one another.

Images