Field of the invention

The invention relates to a lattice structure for forming the reinforcing structure of a reinforced concrete floor, as well as an group of two or more adjacent lattice structures, a floor comprising such lattice structures or such groups of two or more adjacent lattice structures, a method of producing such a lattice structure and a method for producing a floor comprising such lattice structures or groups of two or more lattice structures.

Background of the invention EP 0.552.201 describes a 'pre-fab' reinforced concrete floor element with a lattice structure comprising a lower reinforcement net, an upper reinforcement net and weight-saving bodies arranged between these two reinforcement nets resulting in a lattice structure. Individual lattice structures are used for creating individual, concrete shell floor elements. Such concrete shell floor elements are commercially available as Filigran® floors. Such a pre-fab concrete shell floor element is formed by pouring concrete into the lattice structure to embed the full width of the lower reinforcement net in concrete, creating a concrete shell. After the concrete shell has hardened, the pre-fab floor element is then transported to a construction site where it is installed. Additional concrete is then poured onto the shell to obtain the final floor element. A concrete floor is finally obtained by coupling adjacent floor elements by means of coupling bars or similar means thereby obtaining optimal resistance to shear (in the art the floor is said to behave like a 'disc').

A disadvantage of creating concrete floors by using pre-fab concrete shell floor elements however is that the fitting of the coupling bars at the construction site takes considerable time and effort, e.g. per floor thousands of coupling bars may have to be installed between adjacent floor elements. Furthermore, during transport and installation of the pre-fab element, the weight of the concrete shell itself makes handling of the floor element more difficult. It is therefore an object of the invention to provide a reinforced concrete floor wherein at the construction site the time and effort required for obtaining such a floor is reduced. It is a further object of the invention to facilitate easier handling of the lattice structure of such a floor.

Summary of the invention

Hereto a group of two or more adjacent lattice structures for forming the reinforcing structure of a reinforced concrete floor is provided, comprising a first and a second lattice structure, wherein each lattice structure comprises a lower reinforcement net, an upper reinforcement net and one or more weight-saving bodies arranged between these nets, the weight-saving bodies having a total mass lower than the total volume of the weight-saving bodies multiplied by the density of concrete that is to surround the weight-saving bodies, wherein at an outer circumference of the first lattice structure one of the reinforcement nets protrudes outwardly, in particular sideways, with respect to the other reinforcement net, the other reinforcement net thus being a non-protruding reinforcement net, wherein the protruding reinforcement net of the first lattice structure overlaps a reinforcement net of the second, adjacent lattice structure.

Due to the (sideways) protrusion of one of the reinforcement net of the first lattice structure, preferably in the same direction as the other reinforcement net of the first lattice structure, this protruding reinforcement net can be interconnected to the reinforcement net of the second lattice structure, especially due to the protruding reinforcement net overlapping the reinforcement net of the adjacent lattice structure. Thus, the use of coupling bars is no longer necessary as the individual lattice structures are already connected, thus ensuring effective load transfer between these lattice structures. This saves considerable time at the construction site.

Furthermore, due to the wide availability of factories for producing reinforcement nets or lattice structures, as opposed to factories which are suitable for producing concrete or, generally speaking, factories which are suitable for producing the required concrete floor elements, it is much easier to produce the desired reinforcement structure close to the construction site. Analogously, when producing concrete shell floor elements, a lack of suitable factories hinders distribution of such shell floor elements. Thus, by dispensing with the concrete shell, greater production flexibility is achieved since the reinforcement net/lattice structure can be produced in a much wider variety of locations and closer to the construction site.

Yet another advantage is that building systems like sewer systems, water piping, air conditioning, et cetera, can already be pre-installed in the lattice structure at the factory, achieving an even more significant time gain at the construction site.

An embodiment relates to an aforementioned group wherein the protrusion is about equal to the width of one of the weight-saving bodies. In practice, by using such a protrusion length a strong connection to an adjacent lattice structure can be obtained.

An embodiment relates to an aforementioned group wherein the upper reinforcement net of the first lattice structure forms the non-protruding reinforcement net of the first lattice structure and the lower reinforcement net forms the protruding reinforcement net of the first lattice structure, whereas the second lattice structure has a lower reinforcement net forming the non-protruding reinforcement net of the second lattice structure and an upper reinforcement net forming the protruding reinforcement net of the second lattice structure, wherein the protruding reinforcement net of the first lattice structure overlaps the non-protruding reinforcement net of the second lattice structure and the protruding reinforcement net of the second lattice structure overlaps the non-protruding reinforcement net of the first lattice structure. By doing so, a strong and continuous cage structure capable of transferring tensile loads over a relatively long distance is obtained.

Another aspect of the invention relates to a floor, comprising one or more aforementioned groups of lattice structures wherein the lattice structures are embedded in concrete.

An embodiment relates to an aforementioned floor wherein the lower reinforcement net is embedded in a layer of self-consolidating concrete. Such self- consolidating concrete is relatively fluid and can be handily used to form an initial supportive layer whereupon further concrete can be poured.

An embodiment relates to an aforementioned floor wherein the layer of self- consolidating concrete has a thickness of 5-10 cm, preferably 6-7 cm, such that the lower reinforcement net is fully embedded in the self-consolidating concrete layer.

Another aspect of the invention relates to a method of producing a lattice structure for forming the reinforcing structure of a reinforced concrete floor, the lattice structure comprising a lower reinforcement net, an upper reinforcement net and one or more weight-saving bodies arranged between these nets, the weight-saving bodies having a total mass lower than the total volume of the weight-saving bodies multiplied by the density of concrete that is to surround the weight-saving bodies, wherein at the outer circumference of the lattice structure one of the reinforcement nets protrudes sideways with respect to the other reinforcement net, comprising the steps of:

forming the lower reinforcement net,

- arranging the weight-saving bodies on the lower reinforcement net,

- arranging the upper reinforcement net on the weight-saving bodies, in such a way that at the outer circumference of the lattice structure one of the reinforcement nets protrudes outwardly, in particular sideways, with respect to the other reinforcement net.

An embodiment relates to an aforementioned method, further comprising the following steps:

creating a design of the final reinforcing structure of the final floor to obtained at a construction location,

dividing the final reinforcing structure into smaller, individual lattice structures each having an individual lattice structure design and a unique position within the final reinforcing structure, wherein for each individual lattice structure the steps of the previous paragraph relating to the method of producing the lattice structure are carried out in line with the individual design. By using such an individual design method, even more time is saved at the construction site, as all the pre-designed individual lattice structures can also be produced in advance. Then the individually designed and produced lattice structures can be transported to the construction site and installed according to their unique position within the final reinforcing structure. There, the overlapping net parts can be connected and the pouring of concrete can start. Significant time gains are achieved by doing so.

An embodiment relates to an aforementioned method wherein the individual lattice structure design is created with help of a computer and the individual computer design is subsequently fed into a device capable of producing the individual lattice structure according to the individual computer design. Nowadays, such devices are readily available, though still at a significant cost. Such a device allows a designer to design a final floor reinforcing structure, divide the floor reinforcing structure into smaller individual lattice structures and produce the individual lattice structures all in one go.

An embodiment relates to an aforementioned method wherein one or more building systems like sewer systems, water piping, air conditioning, are pre-installed in the lattice structure prior to transport thereof to a construction site.

Another aspect of the invention relates to a method of producing a floor comprising an aforementioned group of two or more adjacent lattice structures, comprising the steps of:

- arranging formwork at the location where the final floor is to be obtained, - positioning the first lattice structure on the formwork,

- positioning the second lattice structure on the formwork, adjacent to the first lattice structure,

- wherein the protruding reinforcement net of the first lattice structure is caused to overlap a reinforcement net of the second lattice structure,

- pouring concrete into the lattice structures such that the lattice structures are embedded in the concrete.

An embodiment relates to an aforementioned method wherein the step of pouring concrete comprises the following sub steps:

first pouring self-consolidating concrete into the group of lattice structures such that only the lower reinforcement nets are embedded therein,

allowing the self-consolidating concrete to harden,

then pouring regular concrete into the group of lattice structures, onto the hardened layer of self-consolidating concrete, such that the upper reinforcement nets are embedded therein, and

- allowing the regular concrete to harden.

An embodiment relates to an aforementioned method wherein the step of pouring self-consolidating concrete into the group of lattice structures is carried out on a first day and the step of pouring regular concrete into the group of lattice structures is carried out on a second day, being the subsequent day. Thus, the self-consolidating layer of concrete is allowed sufficient time to harden, but not too long as to unnecessarily increase construction time. Preferably, the self-consolidating layer is formed in the afternoon of the first day and the regular concrete layer in the morning of the second day. An embodiment relates to an aforementioned method wherein the lower reinforcement net of the first lattice structure forms the protruding reinforcement net of the first lattice structure and the upper reinforcement net thereof forms the non- protruding reinforcement net of the first lattice structure, whereas the second lattice structure has a lower reinforcement net forming the non-protruding reinforcement net of the second lattice structure and an upper reinforcement net forming the protruding reinforcement net of the second lattice structure, wherein the positioning of the second lattice structure on the formwork, adjacent to the first lattice structure, is carried out by moving, for instance lowering, the second lattice structure and the lower reinforcement net thereof towards the protruding reinforcement net of the first lattice structure, in a direction transversal thereto, until the lower reinforcement net of the second lattice structure is in contact with and overlaps the protruding reinforcement net reinforcement net of the first lattice structure and the protruding reinforcement net of the second lattice structure is in contact with and overlaps the upper reinforcement net of the first lattice structure. In this way, a group of adjacent lattice structures and eventually the final floor reinforcing structure can be quickly obtained.

An embodiment relates to an aforementioned method wherein, when the first and second lattice structures have been produced using an aforementioned method, the first and second lattice structures are positioned on the formwork as to be in correspondence with their unique position within the final reinforcing structure of the final floor.

Brief description of the drawings An embodiment of a lattice structure according to the invention will by way of non-limiting example be described in detail with reference to the accompanying drawings. In the drawings:

Figure 1 shows a cross-sectional view of a first embodiment of a lattice structure according to invention;

Figure 2 shows the group of two individual lattice structures for forming the final floor lattice structure; and

Figure 3 shows a cross-section of a part of the final floor. Detailed description of the invention

Figure 1 shows a cross-sectional view of a first embodiment of a lattice structure 7 according to invention. The lattice structure 7 comprises a lower reinforcement net 2 and an upper reinforcement net 3. Between the reinforcement nets 2, 3 weight-saving bodies 5 are arranged. The weight-saving bodies 5 can be formed by hollow balls (as shown), cubes, or similar structures, as long as the bodies' mass is lower than the bodies' volume multiplied with the density of the concrete that is to be poured around the weight-saving bodies 5. To facilitate positioning of the upper reinforcement net 3 above the lower reinforcement net 2, and to keep the nets 2, 3 properly positioned during the pouring of the concrete, distance holders 4 are arranged between both nets 2, 3. The distance holders 4, for example embodied by lattice girders, have an inverted V-shape for this purpose. The person skilled in the art will understand that other types of distance holders 4 can also be used, such as one-legged or two-legged variants. The reinforcement nets 2, 3 comprise longitudinal reinforcement bars 8 extending in the viewing direction and transversal reinforcement bars 9 extending in a direction perpendicular to the longitudinal reinforcement bars 8. The upper reinforcement net 3 has a projecting (protruding) part 10 in the left part of figure 1, i.e. in the sense that the transversal reinforcement bars 9 and longitudinal reinforcement bars 8 of the upper reinforcement net 3 extend further leftward than the lower reinforcement net 2. The right side of figure 1 on the other hand shows the lower reinforcement net 3 extending further rightward than the upper reinforcement net 3.

Figure 2 shows the assembling of two individual lattice 7 structures (the two individual lattice structures 7 in assembled form leading to the assembly/group 6 of lattice structures as shown in Figure 3) for forming the final floor lattice structure. Preferably, already during the design phase of the final concrete floor, the individual lattice structures 7 are dimensioned for their specific position within that final floor lattice. I.e. in such a way that the individual lattice structures 7 can be assembled relatively quickly on the spot to form the final floor lattice structure, much like assembling the individual pieces of a puzzle. This saves a large amount of work on the construction site, and therefore saves cost.

Adjacent lattice structures 7 are designed in such a way that the projecting bars 10, 11 of the reinforcement net 2, 3 of one lattice structure 7 overlap a certain length of the respective reinforcement net 2, 3 of an adjacent lattice structure 7. Due to these overlapping reinforcement bars 10, 11 the use of additional coupling bars or similar coupling means (usually at the interface of adjacent floor elements) can be avoided, saving time and cost. Furthermore, it is conceivable that only one lattice structure 7 has projecting reinforcement bars/rods and the adjacent lattice structure does not have any. The presence of overlap, and the amount of overlap, depends on the constructive requirements applicable to the floor at that location.

More specifically, the final concrete floor is created by means of the following steps: first the individual lattice structures 7 are each created by providing the lower reinforcement net 2, arranging the weight-saving bodies 5 on the reinforcement net 2, positioning distance holders 4 on the lower net 2 and then arranging the upper reinforcement net 3 on top of the distance holders 4 to form the final lattice structure 7.

The individual lattice structures 7 are then transported to the construction site. Firstly, formwork is arranged at the location where the floor is to be constructed. The formwork can for instance be made of steel or wood. The use of formwork known as 'table formwork' is preferred. The individual lattice structures 7 are then each laid down on the formwork at their designated positions in the final floor lattice structure, much like a puzzle.

After the final floor lattice structure is in place, self-consolidating concrete is poured into the floor lattice structure, embedding the lower reinforcement nets 2 therein. However, other types of concrete are also conceivable. Preferably, this step is carried out during the afternoon. The thickness of the self-consolidating concrete layer is about 6-7 cm.

After the self-consolidating concrete has hardened, regular concrete will be poured into the floor lattice structure. Preferably, this is done the next morning. In any case this step should be carried out within 24 hrs of the pouring of the self- consolidating concrete layer. After the regular concrete has hardened, the final concrete floor is obtained. The final floor thus does not require, or hardly require, the use of coupling bars or similar coupling means due to the bars of one or more reinforcement nets of one lattice structure overlapping the reinforcement nets of adjacent lattice structures.

Figure 3 shows a cross-sectional view of part of the final concrete floor 15. The layer of self-consolidating concrete is denoted by reference numeral 17, the layer of regular concrete by reference numeral 18. The area of overlap of the protruding reinforcement net 10, 11 of one lattice structure 7 and the reinforcement net of the adjacent lattice structure is indicated by 16. The group of the two individual lattice structures is indicated by reference numeral 6.

Thus, the invention has been described by reference to the embodiment discussed above. It will be recognized that this embodiment is susceptible to various modifications and alternative forms well known to those of skill in the art without departing from the spirit and scope of the invention. Accordingly, although a specific embodiment has been described, this is an example only and is not limiting upon the scope of the invention.

Reference numerals

1. Floor

2. Lower reinforcement net

3. Upper reinforcement net

4. Distance holder

5. Weight-saving body

6. Group of lattice structures

7. Lattice structure

8. Longitudinal reinforcement bar

9. Transversal reinforcement bar

10. Projecting upper reinforcement net bars

11. Projecting lower reinforcement net bars

12. -

13. -

14. -

15. Floor part

16. Area of overlap

17. Self-consolidating concrete

18. Regular concrete