EP1908891A2

EP1908891A2 - Composite precast slab for flooring

Info

Publication number: EP1908891A2
Application number: EP07380183A
Authority: EP
Inventors: David Fernández-Ordóñez
Original assignee: Ingenieria de Prefabricados SL
Current assignee: Ingenieria de Prefabricados SL
Priority date: 2006-07-06
Filing date: 2007-06-25
Publication date: 2008-04-09
Also published as: EP1908891A3; ES1063390U

Abstract

The composite precast slab for flooring makes it possible to build self-supporting lightweight floors for large spans, with a smaller weight and much more flexible to be adapted to different geometrical shapes, both in spans and in hollows, and the mechanical requirements of the flooring, and it is possible to combine different reinforcements. It comprises a lower layer or base (2) from which ridges (3) emerge in its end areas, and at least one ridge (4) in its central area of a considerably smaller height and greater width than that of the ridges (3), a reinforcement (5) emerging from the base of this central ridge (4) that in turn comprises a longitudinal reinforcement (6) positioned inside the precast slab (1), another longitudinal reinforcement (6') positioned outside the precast slab (1), and a transverse reinforcement (7) that joins and connects the others.

There follow six sheets of drawings numbered correlatively

Description

FIELD OF THE INVENTION

The present invention relates to a composite precast slab for producing flooring for building low-rise or high-rise buildings, with the currently used depths, so that the flooring is perfectly flush with the beams, flat roof, as is usually required by architects and developers.
The precast slab meets the requirement of being self-supporting during the assembly operations and creation of the flooring to ensure a safe working platform for the workers, whilst also avoiding the need to use additional formwork for the safety thereof.
Its mechanical strength and fire resistance are suitable for the precast slab to be used in spans larger than those that are usual in residential properties, which are currently made using traditional in situ solutions or with prefabricated beam and block elements, also allowing the necessary spaces to be made for inserting installations without lessening the support features thereof.
The invention lies within the technical-industrial sector of construction.

BACKGROUND OF THE INVENTION

Traditionally, in the construction sector in Spain and Europe, and generally in any part of the world, people have been using in situ or prefabricated solutions for the construction or production of flooring. The most commonly used solutions are as follows:

In situ slabs: This is continuous lightweight formwork using concrete, ceramic or polystyrene blocks, between which a separation is left to insert reinforcement. In-situ slabs can be one-way or two-way, the beams have the same depth as the floor and the concrete is continuously poured after positioning the positive and negative distribution bar reinforcement. This solution covers most of the in-situ building market for high-rise residential buildings.
Beam and block slabs: These are one-way slabs with prefabricated linear elements or beams, which can be reinforced or prestressed, and lightweight prefabricated elements or arches that can be ceramic, made of concrete or made of polystyrene. This currently represents most of the prefabricated floors used in houses and high-rise residential buildings.
Hollow core floor slabs: Also called lightweight slabs, they are one-way slabs consisting of a prefabricated piece that makes up most of the section, which is manufactured, like most linear elements, by mechanical means on long casting beds. This type of flooring usually has an in-situ compression layer and has the advantage that it can be self-supporting for all the loads of the floor and it can cover large spans. It is therefore widely used for industrial and commercial buildings.
The disadvantage is that the floor must be directly supported on the supporting elements, beams or walls, and it therefore cannot be used with a flat ceiling without involving significant complications. Its weight is also greater for on-site assembly, as the prefabricated section is almost complete.
Precast floor slabs: These are floor slabs in which part of the floor section is prefabricated, the main advantage of which is that they are lightweight elements for on-site assembly and they also have lightweight form elements, in some cases, and on-site concrete. They make it simple to form connections to create flat a ceiling.

This field includes the following types of precast slabs:

a) Prestressed precast slabs. These are elements with a constant depth of concrete, normally between 4 and 10 cm thick, where the floor is finished with a layer of concrete in situ. They may or may not contain welded-wire reinforcement for handling and the width tends to vary between 0.50m and 2.50m. This type of precast slab is shown in figure 1.
b) Precast slabs with lattice reinforcement. These are precast slabs in which reinforcements are embedded while the layer of concrete is being poured to achieve greater inertia and self-supporting capacity. The purpose of these embedded reinforcements, or lattices, is to provide flexure and shear reinforcement.
In this solution the floor is usually finished by directly pouring on a compression layer or by inserting lightweight form elements, which could be made from polystyrene, between the bars of the lattice. They are reinforced elements and can have welded-wire reinforcement in the lower layer. As they are reinforced, they are easily adapted to complex geometries. This type of precast slab is shown in figure 2.
c) Ribbed precast floor slabs. These are precast slabs in which concrete is poured onto concrete ridges at the same time as the lower layer in order to achieve greater rigidity in the precast slab itself, so that it has the advantage of improving the capacity of the prefabricated piece, although it has the disadvantage of weighing more.
They do not have shear reinforcement embedded in the ridges; instead they are normally reinforced with longitudinal prestressed reinforcements and they can optionally have welded-wire reinforcement, which is not used to calculate the shear force and is used for handling the piece. This type of precast slab is shown in figure 3.

DESCRIPTION OF THE INVENTION

The composite precast slab of the invention provides a perfect solution to the problems posed by the solutions of the prior art by proposing a solution that is simple, effective and functional, which makes it possible to build a lightweight self-supporting concrete floor for large spans with a smaller weight, much more flexible to adapt to different geometrical shapes, in spans and hollow spaces, and the mechanical requirements of the floor, and it is also possible to use different reinforcements.
The precast slab or prefabricated element consists of a lower concrete layer from which concrete ridges and reinforcements emerge, which are simultaneously situated in the prefabricated element itself. The reinforcements can take the form of a lattice or another arrangement such as hoops, although in all cases they are simultaneously present in the prefabricated element.
Therefore, the precast slab combines prestressed and reinforced elements in the same piece for both longitudinal flexure reinforcement and transverse shear reinforcement.
From the manufacturing point of view, the reinforcement of the precast slab is positioned on the casting bed so that, when the prefabricated piece projects, it is perfectly secured thereto.
The area of reinforcement emerging from the prefabricated element can be adapted to each particular case in terms of height, width of the reinforced area, and/or diameter and capacity of the reinforcement that is embedded and emerges from the precast slab.
Likewise, the number and arrangement of the ridges can vary in order to adapt it to each particular site, as can their specific shape, which can be straight or with the form of a compression head on top to improve the single-section mechanical characteristics.
Optionally, the prefabricated element can have nonprestressed reinforcement for shear reinforcement in the concrete ridges emerging therefrom so that it may be used to increase the strength of the piece for special loads. Said nonprestressed reinforcement can emerge through the top of the concrete ridge so that it can be used to improve the connection of the prefabricated concrete when poured on site.
Also, the lower layer of concrete can optionally have welded-wire reinforcement or structural reinforcement.
Therefore, among other advantages and benefits it is possible to produce a piece with better mechanical characteristics than those currently manufactured, both in terms of mechanical capacity and as reinforcement for special loads, as well as being lighter in weight and having greater flexibility, which is essential due to the potential diversity of building sites.

BRIEF DESCRIPTION OF THE FIGURES

To complement this description and in order to aid a better understanding of the invention's characteristics, according to a preferred practical embodiment thereof, there is a set of illustrative and non-limiting drawings integral to said description, which are as follows:

Figure 1: shows an example of the prior art corresponding to a prestressed precast slab.
Figure 2: shows an example of the prior art corresponding to a precast slab with lattice reinforcement.
Figure 3: shows an example of the prior art corresponding to a ribbed precast slab.
Figure 4: shows a front view of the precast slab or prefabricated element in an embodiment according to the object of the present invention.
Figure 5: shows a front view of a smooth floor made using the precast slab or prefabricated element of the present invention.
Figure 6: shows a perspective view of the precast slab or prefabricated element in an embodiment according to the object of the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

In view of figures 4 to 6, it can be observed how the precast slab (1) of the invention comprises a relatively low, flat, elongated lower concrete layer or base (2) from which lateral concrete ridges (3) emerge in its end areas, and a ridge (4) in its central area of a considerably smaller height and greater width than that of the ridges (3).
In turn, a lattice reinforcement (5) of a similar height to that of the ridges (3) emerges from the central ridge (4) and is embedded in it and in the lower concrete layer (2) itself, consisting of a longitudinal reinforcement (6) positioned inside the precast slab (1), another longitudinal reinforcement (6') positioned outside the precast slab (1), and a transverse reinforcement (7) that joins and connects the others. Optionally, the precast slab (1) can be made without a central ridge (4), or rather its height can be zero and therefore the reinforcement (5) emerges directly from the lower base (2).
In a particular embodiment, the reinforcement (5) is a lattice with a triangular form in its front view, as can be seen in figure 4. Likewise, the reinforcement (5) can take the form of a hoop or can be flat, or any other configuration with the same functionality or even a different height.
In another particular embodiment, the lateral ridges (3) comprise a nonprestressed reinforcement to enable it to be used in shear reinforcement, reinforcement which can project from its section to improve the connection with the concrete poured on site.
Optionally, the precast slab (1) can have a prestressed reinforcement (8) or a welded-wire reinforcement (9) in its lower concrete layer (2).
Figure 5 shows an example of floor made with the precast slab (1) that is the object of the invention. It is possible to see two examples of precast slab (1), wherein classic lightweight form elements (10) are positioned between the concrete ridges (3) and the reinforcement (5), the concrete (11) is poured on site to fill the free areas of the precast slab (1), particularly around the longitudinal reinforcement (5), a compression layer (12) is poured on site and a complementary reinforcement (13) is also installed on site, which consists of a welded-wire reinforcement and negative reinforcement.
Finally, it should be mentioned that in another variant of an embodiment, the lateral ridges have a projecting reinforcement and the at least one central ridge is made from concrete.

Claims

Composite precast slab for flooring, characterised in that it comprises a lower layer or base (2) from which ridges (3) emerge in its end areas, and at least one ridge (4) in its central area of a considerably smaller height and greater width than that of the ridges (3), a reinforcement (5) emerging from the base of this central ridge (4) that in turn comprises a longitudinal reinforcement (6) positioned inside the precast slab (1), another longitudinal reinforcement (6') positioned outside the precast slab (1), and a transverse reinforcement (7) that joins and connects the others.
Composite precast slab for flooring according to claim 1, characterised in that it does not comprise a central ridge (4) and therefore the reinforcement (5) emerges directly from the lower base (2).
Composite precast slab for flooring according to any of the previous claims, characterised in that there are two lateral ridges (3).
Composite precast slab for flooring according to any of the previous claims, characterised in that the reinforcement (5) is embedded in the central ridge (4) and in the lower layer or base (2).
Composite precast slab for flooring according to any of the previous claims, characterised in that the lower layer or base (2) is made from concrete and is elongated and flat.
Composite precast slab for flooring according to any of the previous claims, characterised in that the lateral ridges (3) are made from concrete.
Composite precast slab for flooring according to any of the previous claims, characterised in that the reinforcement (5) takes the form of a triangular lattice in its front view.
Composite precast slab for flooring according to any of claims 1 to 6, characterised in that the projecting reinforcement (5) is flat or in the form of a hoop.
Composite precast slab for flooring according to any of the previous claims, characterised in that the lateral ridges (3) comprise a nonprestressed reinforcement to enable it to be used in shear reinforcement.
Composite precast slab for flooring according to claims 1 and 9, characterised in that the nonprestressed reinforcement of the lateral ridges (3) projects from its section to improve the connection with the concrete poured on site.
Composite precast slab for flooring according to any of the previous claims, characterised in that the precast slab (1) has prestressed reinforcement (8) in its lower layer or base (2).
Composite precast slab for flooring according to any of claims 1 to 11, characterised in that the precast slab (1) has welded-wire reinforcement (9) in its lower layer or base (2).
Composite precast slab for flooring according to any of the previous claims, characterised in that the ridges that emerge from its end areas are reinforcement ridges and the at least one ridge that emerges from its central area is made from concrete.