FR2578276A1 - Concrete construction element, particularly floor element, and method for its production - Google Patents

Abstract

The element comprises a reinforced concrete slab 10 which is limited by an external face 12 and by an opposing soffit 14, as well as at least one rib 16, 18, made of prestressed concrete, which is part of the soffit of the slab, the slab being cast after the rib has been produced. The external face 12 has a finished surface cast in one piece on slab formwork, whilst the rib 16, 18 is only partially embedded in the slab, internal reinforcement elements being provided for mechanically joining the slab to the rib.

Description

Concrete building element, in particular floor element, and process for its production.

The present invention relates to a concrete building element, in particular a floor element, as well as a method for its manufacture.

It relates more particularly to such a construction element which comprises a reinforced concrete slab bounded by an external face and by an opposite underside, as well as at least one prestressed concrete rib dependent on the underside of the slab, the slab being cast after the manufacture of the rib.

There are already known such construction elements which can be used as floor elements, the aforementioned external face then constituting the upper face of the slab, and which usually comprise two parallel ribs, such as profiles, beams or beams in prestressed concrete which depend on the underside of the slab.

In the traditional casting process, the prefabricated ribs are arranged on a formwork table of suitable shape which then receives a reinforcement, before the concrete is poured to form the body of the slab.

Such a process can be qualified as a casting process in the place where the formwork face, that is to say the face in contact with the formwork table, happens to be the underside of the slab, while the opposite non-shuttered face is the external face of this slab.

It follows that the external face of the slab does not constitute a formwork or molded face and that it cannot be obtained by casting with the required finish. The external face must then undergo, after demolding or stripping of the element, specific finishing treatments.

Thus, in the case of floor elements, said external face or top face must, after obtaining the slab, undergo a general leveling to allow the subsequent laying of thin floor elements.

On the other hand, in these known construction elements, the ribs must be completely or almost completely coated with the concrete which constitutes the slab to ensure the required mechanical connection between the slab and the ribs, which increases the weight of the element. of construction.

In addition, the known method makes it possible to manufacture, with a formwork table, only one type of construction element.

It is one of the aims of the invention to produce construction elements, especially floor elements, which, after demolding, are completely finished and in particular have an external face in the final form of use of the slab.

It is also an object of the invention to produce such elements which, while being lighter in weight than the elements of the prior art, however have a resistance comparable to, or even greater than, the latter.

It is another object of the invention to provide a process which makes it possible, with the same formwork table, to manufacture different construction elements, each adapted to the needs of the user.

It is yet another object of the invention to provide such a manufacturing process which can be implemented with ribs of very different profiles.

The present invention more particularly relates to a concrete construction element, of the type defined above, the essential characteristic of which resides in the fact that the external face of the slab has a finished surface which comes directly from molding by casting on a formwork table. and that the rib is embedded only partially in the concrete forming the body of the slab, internal reinforcements of the rib being provided to ensure a mechanical connection between the slab and the rib.

According to another characteristic of the invention, the said internal reinforcements are constituted by transverse reinforcements which have projecting parts suitable for being embedded in the concrete of the slab.

The manufacturing method of the invention essentially comprises the operations consisting in manufacturing a reinforcement intended for the slab, in placing this reinforcement above a horizontal formwork table, in being placed on the formwork table in at least one rib which has internal reinforcements with projecting parts, so that the projecting parts are oriented towards the formwork table, to pour the concrete from the slab and, after setting this concrete, to demold the building element thus formed.

The invention will be better understood from the description which follows, given by way of example, and with reference to the appended drawing, in which - Figure 1 is a cross-sectional view of a building element according to the invention; - Figure 2 is a view below of the building element of Figure 1; - Figure 3 is a side view of the building element of Figure 1; - Figures 4, 5 and 6 show different rib profiles used for the implementation of the invention; - Figure 7 is a partial longitudinal sectional view of a rib, showing more particularly its internal reinforcements, Figure 8 is a partial cross-sectional view of a building element according to the invention, this view corresponding to a cut along the line
VIII-VIII of figure 9 ;; - Figure 9 is a sectional view taken along the line IX-IX of Figure 8; - Figures 10A to 10G illustrate different successive phases of the method of the invention; - Figure it is a partial cross-sectional view of a construction element according to the invention, comprising an external end reinforcement, constituted by a box; - Figure 12 is a partial side view of the building element of Figure II; - Figure 13 is a perspective view of the box used in the construction element of Figures II and 12; - Figure 14 is a partial cross-sectional view of another construction element comprising an external end reinforcement, constituted by a reinforcement; - Figure 15 is a side view of the building element of Figure 14 ;; FIG. 16 is a view in partial longitudinal section of another construction element according to the invention; - Figure 17 is a partial end view of the element of Figure 16; - Figure 18 is a. perspective view of an end reinforcement of the element of FIGS. 16 and t7; and - Figure 19 is a partial perspective view of a rib and an associated concrete block of the element of Figures 16 and 17, the concrete slab being removed.

FIGS. 1 to 3 show a concrete construction element intended to be used in particular as a floor element. However, such a construction element can find other applications, in particular as a roofing element, or even as a cladding element, the element being in the latter case disposed in a vertical position.

The building element comprises a reinforced concrete slab 10 bounded by an external face 12, the latter constituting the top face in the case of a floor element, and by an opposite underside 14, as well as two ribs 16 and 18 in prestressed concrete which are dependent on the underside 14 of the slab.

The slab 10 has a generally rectangular shape and is limited by two opposite end edges 20 and 22 and by two opposite lateral edges 24 and 26.

The edges 20 and 22 are flat edges which extend perpendicular to the face 12 of the slab, while the edges 24 and 26 are chamfered (cf. FIG. 1) to allow, as is well known, to form a concrete connection joint between two taped Jux elements.

The ribs 16 and 18 are prestressed concrete profiles having a rectangular section. These ribs have longitudinal reinforcements making it possible to exert a prestress in the longitudinal direction of the ribs. They also include transverse reinforcements which, as will be seen below, make it possible to form a mechanical connection between the ribs on the one hand and the slab on the other hand.

The ribs 16 and 18 have a length slightly less than that of the slab so as to provide on the underside 14, near the end edges 20 and 22, support zones 28 and 30. These zones support are intended to allow the construction element to rest later, by its two ends, on two suitable support surfaces, for example on two horizontal support beams.

The ribs 16 and 18 are arranged parallel to each other and at a small distance from the lateral edges 24 and 26, thus providing marginal zones 32 and 34 between each of the lateral edges and the rib which is immediately adjacent to it. The thickness of the slab 10 may be greater in the region of the marginal zones 32 and 34 than in the central region between the two ribs 16 and 18.

The reinforced concrete slab 10 has internal reinforcement as well as irons 36 and 38 protruding from the shore 20 and irons 40 and 42 protruding from the shore 22, these irons in particular allowing the handling of the construction element and the anchoring in the supporting structure
As will be seen in more detail lo-in, the deconstruction element shown in Figures I to 3 is manufactured by a reverse casting process in which the face 12 came directly from molding by casting on a table formwork, this equips to obtain a perfectly finished surface. During the manufacturing process, the ribs 16 and 18, and more particularly their respective longitudinal faces 44 and 46, are embedded only partially in the slab.

In practice, it suffices that the faces 44 and 46 of the ribs sink over a short distance, for example of the order of 1 or 2 cm, into the concrete constituting the slab. The mechanical connection between the ribs 16 and 18 and the slab 10 is ensured by internal reinforcements of the ribs 16 and 18 which protrude respectively from the faces 44 and 46.

The pre-stressed concrete ribs used for the implementation of the present invention may have different profiles, as shown by the nonlimiting examples illustrated in FIGS. 4 to 6.

Figure 4 shows a rib whose profile has the general shape of a T, shown here in the inverted position.

This rib is provided for example with longitudinal reinforcements 50 ensuring, as is well known, the prestressing of the rib in its longitudinal direction.

This rib also has internal reinforcements which are partially embedded in the concrete and which have projecting parts such 52, protruding outside the longitudinal face 54 of the rib, corresponding to the top of the T-profile (in the inverted position).

Figure 5 shows a rib 56 in profile. rectangular, provided with longitudinal reinforcements 58. It further comprises transverse reinforcements having projecting parts 60 projecting from a longitudinal face 62.

The rib 64 shown in Figure 6 has a square profile and it is internally provided with longitudinal prestressing frames 66. It further comprises transverse frames which have projecting parts such 68, protruding from the longitudinal face 70 of the rib
The projecting parts, such as 52, 60 and 68, which protrude outside a longitudinal face of the rib, are suitable for being embedded in the concrete of the slab t0, during the manufacture of the construction element.

Figure 7 shows the arrangement of the transverse reinforcements of a rib, in this case the rib 16 of the element of Figures 1 to 3, of which only half has been shown.

This rib 16 has internal reinforcements which are distributed over the entire length of the rib.

The internal reinforcements of the rib 16 comprise, in the end regions of this rib, for example in the end region 72, internal reinforcements such as 74, and in the central region of the rib of the reinforcements 76, 78, 80 , 82, etc.

The end fittings 74 have projecting parts each terminated by a hook 84 suitable for anchoring in the reinforcement of the slab. The internal reinforcements 76, 78, 80 and 82 are here constituted by sinusoidal irons which can be placed one after the other, like the irons 80 and 82, or offset, like the irons 76 and 78, to ensure a greater density of reinforcement in the vicinity of the ends of the rib.

Reference is now made to FIGS. 8 and 9 which show more particularly the constitution of the end frame 74 and the manner in which this frame 74 is caught in the reinforcement of the reinforced concrete slab.

The frame 74 comprises stirrups 861, 862 and 863 in the general shape of a U which are each arranged in a plane perpendicular to the longitudinal direction of the rib. Each stirrup, for example the stirrup 861, has two projecting branches 881 and 882 which protrude from the longitudinal face 44 of the rib and which each end in a hook 841. Similarly, the stirrups 862 and 863 are provided hooks 842 and 843. The stirrups $ 6 i61, 862 and 863 are connected to each other by longitudinal struts, that is, struts 90? and 902 which protrude from the end of the rib to form a part 922 in the form of a butt.

The stirrups are also joined by longitudinal struts 941 and 942 which are both welded inside the base of the stirrups and which have a straightened part, for example the part 962, parallel to the branches of the stirrups, this straightened part being itself terminated by a hook such as 982. The hooks 841, 842, 843 and 982 are provided for hooking in transverse bars 100 forming part of the reinforcement of the slab. The irons 100 are welded onto longitudinal irons 102 by forming a welded mesh, as is well known in the art. The reinforcement of the slab also comprises transverse irons 104 arranged at a level lower than that of the irons 100.

The end reinforcement 74 thus makes it possible to "raise" the shearing force in support of the slab (zone 28).

The establishment of the transverse reinforcements in the ribs usable for the implementation of the present invention can be carried out, for example, in accordance with the teachings of French patent 72 31 148 of the Applicant. Thus, these transverse reinforcements can be put in place in the frictional poured concrete, by introducing them by vibration.

As also shown in FIG. 8, a vertical slit 105 is formed longitudinally in the thickness of the concrete slab in the marginal zone 32. This slit which is obtained during the casting of the slab using an appropriate shape is intended for allow the subsequent fixing of a false ceiling using appropriate fixing means.

Reference is now made to FIGS. 10A to 10G to describe the method of the invention.

To use this method, a formwork table 106 is used, comprising a horizontal formwork surface 108 which allows the simultaneous construction of two construction elements of the invention by a reverse casting process.

As shown in FIG. 10A, the surface 108 is arranged between two external strips 110 and 112 and it receives three spacing rules 114, 116 and t18 which make it possible to provide chamfered lateral edges in the two construction elements thus manufactured. previously described with reference to Figures t to 3.

Then there is on the surface t08 a reinforcement 120 between rules 114 and 116 and a reinforcement 122 between rules 116 and 118. The reinforcements 120 and 122 are intended to form the internal reinforcements of the respective slabs of the two construction elements (FIG. 10B ).

As shown in Figure tOC, there are then on the formwork table the ribs 16 and 18 intended for one of the construction elements and the ribs 16 'and 18' intended for the other construction element. These ribs are arranged upside down, so that the projecting parts of their internal transverse reinforcements are oriented downward to interpenetrate with the reinforcements 120 and 122. These ribs thus placed upside down are laid and wedged using appropriate rules and wedges.

This operation being completed, the concrete intended to form the slabs 10 and 10 'is poured. This concrete coats the reinforcements of the two slabs as well as the projecting parts of the transverse internal reinforcements of the ribs. These ribs are also found embedded very slightly in the concrete constituting the slabs (Figure 10D).

After the concrete has set by steaming, the two elements can be lifted using a suitable lifting device 124 capable of lifting each of the construction elements by the parts of reinforcement projecting at the ends of the banks (FIG. 10E). As this figure also shows, it is preferable that the strips 110 and 112 of the table 106 and the rules 114 and 116 associated therewith be retractable, for example by pivoting outwards, to facilitate the lifting of the two elements. of construction.

Each of the construction elements can then be turned over, as shown in FIG. 10F, using a spreader 126 comprising two parts 126a and 126b suitable for coming into contact respectively with the external face of the slab 10 and the lower part of the ribs 16 and 18. The elements can then be stored, for example on top of each other, preferably with the interposition of an intermediate element 127, as shown in FIG. 10G.

The method described above makes it possible to obtain construction elements whose external face has a finished and flat surface, obtained directly from molding, because this face was in direct contact with the surface 108 of the formwork table.

Reverse pouring makes it possible to have different heights or thicknesses of the concrete slab, for example a smaller thickness in the central region and greater thicknesses in the marginal regions, as described above with reference to FIGS. 1 to 3.

The assembly of the reinforcement of the slab and the ribs can be carried out on an assembly table, the ribs being arranged upside down or upright. This assembly can also be done directly on the formwork table, the ribs then being arranged upside down. It will be noted that the process is very flexible to use since the ribs can be placed in any desired position and that the thickness of the concrete slab can also be adjusted as desired. It is also possible to use any suitable type of rib and to change the rib profile if desired, without the need to use a different formwork table.

In addition, with the same formwork table, construction elements of different widths or lengths can be produced, provided that the spacing rules are moved.

The invention also provides that, in each of the end regions of the rib (s), an external reinforcement may surround the rib and be connected to the reinforcement of the slab, while being partially embedded in the concrete of the slab.

FIGS. 11 to 13 illustrate a first embodiment in which citte, the external armature, is a box 128 made of sheet metal, for example a galvanized or non-galvanized embrace, which has a bottom 130 and two parallel sides 132 and 134 provided with orifices 135 and 137 for the passage of transverse bars such as the bars 100 forming part of the reinforcement of the slab. Such an external reinforcement is usable whatever the type of rib used, but especially with ribs of the joist type having a T-shaped section, like the joist 136.

During the manufacture of the building element, there is at each end of the ribs such a box t28 so that it can maintain the ribs in good position, while being connected to the mocking iron of the slab. The pouring of the concrete of the slab is carried out, as previously, in a position called "upside down", that is to say in an inverted position with respect to that of FIG. 11. The top 138 of the T-shaped rib is partially embedded in the slab, while the underside of this rib bears against the bottom 130 of the box. To facilitate the holding of the rib in these two end boxes, the bottom of the box 130 and the bottom of the other end box on the rib 136.

In addition, the sides 132 and 134 of the box are provided with lugs 140 and t42 which are suitable for retaining the rib bearing on the bottom 130. These lugs here come to bear under the horizontal bar, or heel, of the profile in T shape.

The manufacture of such a construction element remains by tailors identical to that previously described. Note that, if desired, the external reinforcement or box 128 can receive a layer of protective concrete 144 with a skin reinforcement 146.

As shown in FIG. 12, after formwork has been removed and the building element has been turned over, it can be used as a floor element and bear at each of its ends on a supporting element, such as element 148 shown in figure 12.

FIG. 13 more particularly illustrates the structure of the box seen in perspective.

Figures 14 and 15 show another embodiment a has an external end frame. This end reinforcement is here produced in the form of a reinforcement 150 which comprises stirrups t521 1522, 1523 and 1524 in the form of U each arranged in a plane perpendicular to the longitudinal direction of the rib, these stirrups being connected together by longitudinal struts 154 and 156. The ends of the legs of the stirrups are curved to form hooks 1581, 1582, 1583 and 1584 suitable for hanging in the reinforcement of the slab, more particularly in the irons 100. This external reinforcement 150 has therefore a certain resemblance to the internal frame 74 described above with reference to Figures 8 and 9. However, in this case, the U-shaped stirrups are dimensioned so as to be able to frame the profile of the rib, the latter having preferably a T-shaped section as already indicated.

The external reinforcement 150 must receive a layer of protective concrete t44 and a skin reinforcement 146.

The manufacturing is carried out in the same manner as described above.

The use of external reinforcements at the ends of the ribs is optional, but it nevertheless constitutes a preferred embodiment of the invention, insofar as it makes it possible to use very widespread and inexpensive inverted T-ribs.

We now refer to Figures 16 to 19 illustrating another embodiment of the invention.

In this embodiment, the rib 136 is a T-beam, each end of which, for example the end 160, stops at a distance from the support zone 28 of the underside 16 of the slab t0 which is intended to rest on a horizontal support element 48. The distance between the end 160 and the vertical edge 162 of the support element can be for example from 15 to 20 cm. According to the invention, a block 164 of parallelepiped shape is formed in the concrete constituting the body of the slab, during the casting of this slab using a suitable mold.

This block is cast so as to be dependent on the end 160 of the rib, while being located in the extension of the rib, which ensures a connection between the end of the rib and the slab.

This block incorporates internal reinforcement 166 to raise the shearing force in the support zone 28 of the slab. This raising is necessary because the building element rests on the supporting element 148, not by the ribs, but by the underside of the slab itself.

As shown more particularly in FIG. 18, the internal reinforcement 166 comprises two vertical rectangular frames 168 and 170, acting as hooping frames, joined at their lower part by longitudinal struts 172 and 174 and at their upper part by two beds of loops 176 and 178 suitable for being embedded in the thickness of the slab to ensure the resistance to bending of the support console (zone 28).

The beds 176 and 178 are similar to the elements 922 and 102 mentioned above with reference to FIGS. 9 and 15. The lower loop 178 in the form of a hairpin can be replaced by two parallel elements each terminated by a curved part in the form of stick.

The reinforcement 166 further comprises a frame 180 available obliquely, for example substantially at 450 with respect to the horizontal, to raise the shearing force up to the support zone 28.

As shown more particularly in FIG. 19, the respective upper ends of the frames 168, 170 and 180 protrude from the block 164 so that they can be embedded in the thickness of the slab.

In this embodiment, the transverse reinforcements of the rib 136 also include protruding parts 52 to ensure the mechanical connection between the rib and the slab.

The ends of the longitudinal reinforcements 50 for prestressing the rib are bent in the direction of the slab and also anchored in the block 164 (Figures 16 and 17).

The construction elements of the invention can be used not only to produce floor elements, but also to produce roof elements or even cladding elements, the elements in the latter case being arranged in a vertical position.

In the case where the building element is a floor element, it may include means, such as the slot 105 described with reference to FIG. 8, to allow the fixing of a false ceiling.

In general, the fixing of a false ceiling can be done by any known means, in particular by drowning in the slab hanging rods, smooth or threaded, or even flat irons intended to receive adjustable legs.

In another variant, the T-shaped rib can receive clean collars to pinch the lower wing of the beam. On the other hand, taking into account the flatness of the upper face of the element, it is possible to fix with precision, by this reference, suspension members already adjusted to the dimension of the plates forming the false ceiling.

Claims (19)

Claims. 1. A concrete building element, in particular a floor element, comprising a reinforced concrete slab (10) bounded by an external face (12) and by an opposite underside (14), as well as at least one rib (16 , 18) in pre-stressed concrete dependent on the underside of the slab, the slab being cast after the manufacture of the rib, characterized in that the external face (12) of the slab has a finished surface coming directly from molding by casting on a formwork table (106) and in that the rib (16, 18) is only partially embedded in the concrete forming the body of the slab, internal reinforcements (74, 76, 78, 80, 82) of the rib being provided to ensure a mechanical connection between the slab and the rib. 2. Construction element according to claim 1, characterized in that the internal reinforcements (74, 76, 78, 80, 82) are constituted by transverse reinforcements which have projecting parts suitable for being embedded in the concrete of the slab ( 10). 3. Construction element according to one of claims 1 and 2, characterized in that, in the end regions (72) of the rib (16), the internal reinforcements (74) have protruding parts each terminated by a hook (84) suitable for hanging in the reinforcement of the slab. 4. Building element according to claim 3, characterized in that the internal armor plates (74) comprise stirrups C86 ,, 862 and 863) in general U shape, each arranged in a plane perpendicular to the longitudinal direction of the rib, these stirrups comprising two projecting branches (88, 882, ...) each terminated by a hook (84î). 5. Building element according to one of claims 1 to 4, characterized in that in each of the end regions of the rib is provided an external frame (128, 150) which surrounds the rib, is connected to the reinforcement of the slab and is partially embedded in the concrete of the slab. 6. Construction element according to claim 5, characterized in that the external frame is a box (128) in sheet metal having a bottom (t 30) and two parallel sides (132, 134) provided with orifices (135, 137) for the passage of transverse bars (100) forming part of the reinforcement of the slab. 7. Construction element according to claim 6, characterized in that the bottom (130) of the box (128) is glued to the rib (136).  8. Building element according to one of claims 6 and 7, characterized in that the rib (136) is a beam having a T-shaped section whose apex (138) is embedded only partially in the slab and whose the underside comes to bear against the bottom (130) of the box, and in that the sides (132 and 134) of the box are provided with lugs (1-40, 142) capable of retaining the rib in support on the bottom. 9. Building element according to claim 5, characterized in that the external reinforcement is produced in the form of a reinforcement (150) comprising stirrups (tu21, 1522, 1523, 1524) in the form of U each arranged in a plane perpendicular to the longitudinal direction of the rib (136) and connected together by longitudinal ropes (154, 156), the ends of the stirrup branches being bent in the form of hooks (1581, 1582, 1583, 1584) to hang in the reinforcement of the slab. 10. Building element according to one of claims 5 to 9, characterized in that the external reinforcement (128, -150) receives a layer of protective concrete cl44) with a skin reinforcement (146).  11. Construction element according to one of claims R and 2, characterized in that, the rib being a T-beam (136), each end of which (160) stops at a distance from a bearing zone (28 ) of the subface (16) of the slab (10), a block (164) formed in the concrete of the slab is dependent on said rib end, this block incorporating internal reinforcement (166) to raise the shear force in said support area of the slab. 12. Building element according to claim 11, characterized in that the internal reinforcement (166) comprises two vertical rectangular frames (168, 170) joined at their lower part by longitudinal struts (172, 174) and at their upper part by two beds of loops (176, 178) suitable for being embedded in the thickness of the slab, as well as a frame (180) arranged obliquely to raise the shearing force up to the support zone. 13. Building element according to one of claims t to t2, characterized in that it comprises two parallel lines (16, 18). 14. Construction element according to one of claims I to 13, characterized in that it is produced in the form of a floor element. 15. Building element according to claim 14, characterized in that it comprises means (for example 105) for fixing a false ceiling. 16. A method of manufacturing a building element according to one of claims 1 to 15, characterized in that one manufactures a reinforcement (120, 122) intended for the slab, this reinforcement is placed above a horizontal formwork table (106), at least one rib (16, 18, 16 ', 18') is arranged on the formwork table which has internal reinforcements having projecting parts, so that these projecting parts are oriented towards the formwork table, the concrete is poured from the slab and, after setting of the concrete, the construction element thus formed is demolded. 17. Method according to claim 16, characterized in that several construction elements are simultaneously produced on the formwork table (106), spacing rules (114, 116, 1t8) being provided to delimit the respective edges of the slabs of these elements. 18. Method according to one of claims 16 and 17, characterized in that one regulates the position and spacing of the ribs by means of rules and shims. 19. Method according to one of claims 16 to t8, characterized in that, after demolding of the construction element, it is turned over by a lifting beam (126).