EP2500481B1 - Infilling formwork elements for floors, made of foamed plastic material - Google Patents

Description

The present invention relates to the field of shuttering formwork floors, cellular plastic material.

For good thermal insulation of buildings, it is known, for the realization of a floor, to provide longitudinal joists, spaced apart, and to fill the space between the joists interjoists (also called "hourdis") in polystyrene positioned between them and building on them. The interjoists are aligned longitudinally to cover the space between the joists over their entire length. The joists are for example concrete.

A concrete screed is then poured on the sealed assembly formed by the joists and interjoists, so as to form the floor. The interjoists thus form elements of formwork of the concrete while ensuring good thermal and acoustic insulation of the floor obtained. Interjoists are indeed planned not to be removed.

FR-A-2,872,187 and FR-A-2,871,489 , which comprises all the features of the preamble of claim 1, describe examples of floor form interjoices, of expanded polystyrene.

More precisely, the interjoists described in the document FR-A-2871489 have at their opposite lateral ends respectively two opposite props of vertical support on the joists. The spikes extend over the entire length of the interjoists, which is of identical section over its entire length.

The lower part of each spoiler is defined by a longitudinal rabbet, that is to say a notch substantially at right angles, formed in the interjoisn along its entire length.

The rabbet thus defines a horizontal face of vertical support on a joist, which horizontal face belongs to the support spoiler, and a vertical face of horizontal support on the same joist, which vertical face is located immediately below the support spoiler .

Under the rabbet, on one side of the interjoists, can extend, as described in FR-A-2,871,489 , a tongue intended to cover the face lower joist. The tongue forms a lateral extension of the interjoists relative to the corresponding spoiler.

A disadvantage of these interjoists is that, being made in a relatively fragile material, they are relatively fragile and can break during the casting of the concrete screed if they are not sufficiently sized.

One solution may be to increase the dimensions of the support spikes but this solution is not satisfactory, the dimensions of interjoists being generally imposed.

Another solution could be to increase the density of the interjoists material, but this would also increase its cost.

FR-A-2,871,489 teaches to integrate reinforcement elements in cavities formed in the body of interjoists. In addition to being expensive, this solution is still not entirely satisfactory from the point of view of the mechanical strength in vertical load of interjoists.

• une face d'appui vertical sur la solive de support correspondante et délimitant la partie inférieure du béquet latéral d'appui respectif ; et
• sous le béquet latéral d'appui, une face d'appui horizontal sur la même solive de support,

dans lequel l'entrevous présente, pour la ou chaque face latérale délimitant un béquet latéral d'appui, au moins une fente longitudinale interne ouverte et non traversante s'étendant respectivement depuis ladite face latérale au niveau de la partie inférieure de la face d'appui horizontal ou sous la face d'appui horizontal, vers l'intérieur du corps de l'entrevous.One aspect of the invention relates to a floor formwork interjoists according to claim 1, the body of which is made of cellular plastic material, the interjoists being delimited by an upper face, a lower face and four faces joining the upper face and the face. lower, of which two opposite transverse faces and two opposite lateral faces,
at least one of the lateral faces delimiting a vertical support side spoiler of the interjoists on a support joist,
the interjoists having on the or each lateral face delimiting a lateral support spoiler, a longitudinal cut in a corner, for example a notch at right angles, forming two contiguous faces:

• a vertical bearing surface on the corresponding support joists and delimiting the lower part of the respective lateral support spoiler; and
• under the lateral support spoiler, a horizontal bearing face on the same support joist,

in which the interjoists have, for the or each lateral face delimiting a lateral support spoiler, at least one open and non-traversing internal longitudinal slot respectively extending from said lateral face to level of the lower part of the horizontal bearing face or under the horizontal bearing face, towards the inside of the body of the interjoists.

• la ou chaque fente a une géométrie et une position adaptées pour qu'une augmentation de la charge verticale sur la face supérieure de l'entrevous, notamment sur la portion centrale de la face supérieure, induise un écartement des faces opposées d'appui horizontal lorsque l'entrevous est en appui sur les solives de support ;
• la ou chaque fente présente une portion dont au moins une inclinaison locale est comprise entre 0° et 60° par rapport à l'horizontale, par exemple une fente de section transversale courbe ou droite ;
• la ou chaque fente est ouverte sur toute la longueur de l'entrevous, d'une face transversale à l'autre ;
• la ou chaque fente est ouverte sur une largeur inférieure ou égale 5mm ;
• la ou chaque fente est ouverte sur une profondeur maximale d'au moins 20mm, de préférence sur une profondeur d'au moins 50mm ;
• ladite face d'appui vertical et ladite face d'appui horizontal sont planes et forment entre elles un angle entre 60° et 120° ;
• la ou chaque face d'appui vertical est horizontale et/ou la ou chaque face d'appui horizontal est verticale ;
• l'entrevous présente une languette faisant saillie latéralement par rapport au béquet latéral correspondant, et destinée à s'insérer sous la solive de support sur laquelle ledit béquet latéral vient prendre appui ;
• la bouche de la ou chaque fente étant au niveau de la languette ou au-dessus de la languette ou de préférence au niveau de l'arrête formée à la jonction de la languette et de ladite face verticale d'appui horizontal, du côté de la languette et/ou du côté opposé à la languette ;
• l'entrevous comprend deux béquets latéraux opposés d'appui, l'entrevous présentant ladite feuillure et ladite fente sur chacune des deux faces latérales opposées ;
• le matériau plastique alvéolaire a une masse volumique comprise entre 10 et 50kg/m³ ;
• le matériau plastique alvéolaire a un module d'Young compris entre 0,5 MPa et 10 MPa ;
• l'entrevous est intégralement constitué de matériau plastique alvéolaire ;
• le matériau plastique alvéolaire est un polystyrène expansé ;
• l'entrevous est dépourvu d'éléments de renfort, par exemple rapportés sur le corps de l'entrevous ou insérés dans le corps de l'entrevous.

According to particular embodiments, the interjoists comprise one or more of the following characteristics, taken separately or in any technically possible combination:

• the or each slot has a geometry and a position adapted so that an increase in the vertical load on the upper face of the interjoists, in particular on the central portion of the upper face, induces a spacing of the opposite faces of horizontal support when the interjoists are supported on the supporting joists;
• the or each slot has a portion of which at least a local inclination is between 0 ° and 60 ° relative to the horizontal, for example a curved or straight cross-section slot;
• the or each slot is open over the entire length of the interjoists, from one side transverse to the other;
• the or each slot is open on a width less than or equal to 5mm;
• the or each slot is open to a maximum depth of at least 20mm, preferably to a depth of at least 50mm;
• said vertical bearing face and said horizontal bearing face are flat and form between them an angle between 60 ° and 120 °;
• the or each vertical support face is horizontal and / or the or each horizontal support face is vertical;
• the interjoists has a tongue protruding laterally relative to the corresponding lateral spoiler, and intended to be inserted under the support bracket on which said lateral spoiler bears;
• the mouth of the or each slot being at the level of the tongue or above the tongue or preferably at the edge formed at the junction of the tongue and said vertical face of horizontal support, the side of the tongue and / or the opposite side to the tongue;
• the interjoists comprises two opposing lateral support spikes, the interjoists having said rabbet and said slot on each of the two opposite lateral faces;
• the cellular plastic material has a density of between 10 and 50 kg / m ³ ;
• the cellular plastic material has a Young's modulus of between 0.5 MPa and 10 MPa;
• the interjoists are entirely made of cellular plastic material;
• the cellular plastics material is expanded polystyrene;
• the interjoists are devoid of reinforcement elements, for example reported on the body of the interjoists or inserted in the body of the interjoists.

The interjoists have the advantage of having a good resistance in vertical load and a relatively low manufacturing cost.

The presence of the slots and their positioning at the horizontal bearing faces or under the latter, allow to resume the vertical load forces exerted on the upper face of the interjoists by horizontal support of so-called vertical faces on the joists. The stresses are thus transferred from the support spikes to the horizontal bearing faces, which reduces the shear stresses in the interjoists. The breaking strength in charge of interjoists is improved.

In tests, it was found that the rupture was no longer initiated at the level of the support spikes, but in the central part of the interjoists, where the quantity of material is the largest, which indicates a optimal load resistance of interjoists.

Thin and deep cracks have proven to lead to good results.

In the case of the presence of a tongue, the slot may advantageously start from the stop joining said horizontal bearing face and the tongue, that is to say from the lower end of the horizontal bearing face.

According to another aspect of the invention, the invention relates to a method according to claim 8 for manufacturing a interjoists as described above.

• la ou chaque fente est découpée dans le corps de l'entrevous, par exemple au moyen d'un fil ;
• la ou chaque fente est formée par moulage dans le corps de l'entrevous, par exemple au moyen d'un moule muni d'un ou plusieurs tiroirs amovibles propres à former la ou chaque fente et à être retirés pour faciliter le démoulage ;

According to particular embodiments, the method has one or more of the following characteristics, taken separately or in any technically possible combination:

• the or each slot is cut in the body of the interjoists, for example by means of a wire;
• the or each slot is formed by molding in the body of the interjoists, for example by means of a mold provided with one or more removable drawers suitable for forming the or each slot and to be removed to facilitate demolding;

Another aspect of the invention relates to a method of constructing a floor according to claim 10 comprising a step of placing interjoists on supporting joists to form a waterproof form, and a step of casting a screed of concrete on the formwork thus formed.

According to a particular embodiment of the manufacture of the floor, the or each vertical support surface of at least some interjoists bears on a horizontal face of the corresponding support joists and the or each horizontal support face positioned facing a vertical face of the same support joist.

The use of a wire to form the slot is particularly advantageous in case of cutting the interjoists by a wire in a block of cellular plastic material. This method makes it possible not to increase the manufacturing cost significantly for the production of the slots. In addition, this method is advantageous for forming a fine and deep slot.

In another aspect there is provided a method of constructing a floor using the interjoists described above.

Note that throughout the text, "slot" means an opening cavity delimiting a long, narrow mouth. The slot preferably has a mouth with straight and parallel edges. In all cases, the length of the mouth of the slot is much greater than its width, at least ten times greater.

"Longitudinal" means that the slot has a greater longitudinal extent than its transverse extent, the longitudinal reference being the length of the interjoists, which length of the interjoists is understood as the direction parallel to the longitudinal axis joists. Except in case of truncation of interjoists, the length of the interjoists is also the largest of the three dimensions of interjoists.

"Open slot" means an unfilled slot, ie no insert is present in the slot or, if an insert partially fills the slot, only the open slot is considered to be part of the slot. remaining of the slot.

Also note that support "vertical" or "horizontal" must be understood broadly and not strictly. "Vertical" support has a larger vertical component than the horizontal component and a "horizontal" support a larger horizontal component. These terms are understood as charges in the use configuration of interjoists. The horizontality reference is the longitudinal axis of the joists and therefore also the length of the interjoists, throughout the text.

The term "horizontal face" and "vertical face" respectively means a substantially horizontal face and a substantially vertical face once the interjoists in position on the joists.

The definitions above are valid throughout the text.

• la figure 1 est une vue schématique en perspective partielle de deux entrevous disposés sur des solives ;
• la figure 2 est une vue schématique en coupe de l'entrevous central de la figure 1, avec en trait pointillé la ligne de rupture de l'entrevous en charge verticale ;
• les figures 3 à 6 illustrent des exemples de réalisation d'entrevous ; et
• les figures 7 et 8 illustrent des résultats de calculs numériques pour un profil de fente analogue à celui de la figure 2.

The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the appended drawings, in which:

• the figure 1 is a schematic partial perspective view of two interjoists arranged on joists;
• the figure 2 is a schematic sectional view of the central interjoists of the figure 1 , with dashed lines the line of rupture of the interjoists in vertical load;
• the Figures 3 to 6 illustrate examples of realization of interjoists; and
• the Figures 7 and 8 illustrate numerical calculation results for a slit profile similar to that of the figure 2 .

For more readability, the reference numbers have not been included in all the drawings.

As illustrated on the figure 1 interjoists 1 are used to make floors of buildings, including floors between floors.

For this purpose, the interjoists 1 are aligned longitudinally between longitudinal support beams 4 parallel to each other, which are for example concrete.

The interjoists 1 are more particularly between each pair of adjacent joists 4 and rest at their opposite lateral ends on the two respective joists 4. They are aligned longitudinally between the joists 4 and thus form with the latter a sealed form on which a concrete screed (not shown) is then cast.

Entrevous 1 are intended not to be removed. They contribute to the thermal and acoustic insulation of the floor, which thus includes interjoists 1, support joists 4 and the screed.

Alternatively, the material of the screed is not a concrete. In general, the screed is in a material of any suitable type, for example an anhydrite screed.

Alternatively, the joists 4 are not concrete. They are for example metallic or in a material of any suitable type.

The figure 2 illustrates in more detail a cross section of a interjoists 1, which in this example has a constant cross section over its entire length. It is indeed an intervous formed by cutting in a block of cellular plastic material and this process generally involves identical cross sections.

Alternatively, however, for example if the interjoists 1 is formed by molding, its cross sections are for example different, especially because of the possible presence of cavities in the central portion.

The interjoists 1 forming the floor are identical and only one of them is described. Note, however, that the interjoists 1 located at the longitudinal ends of a line of interjoists 1 can of course be truncated.

The interjoists 1 is of cellular plastic material, that is to say that its body is made of cellular plastic material, which does not exclude the presence of other materials reported on or present in the interjoists 1.

In the examples shown, the interjoists 1 is nevertheless entirely made of cellular plastic material, that is to say that the interjoists 1 is in particular devoid of reinforcing elements, for example reported on the body of the interjoists 1 or inserted into the body of the interjoists 1.

The interjoists 1 is delimited by an upper face 10A, an opposite lower face 10B and four faces 10C, 10D, 10E, 10F joining the upper face 10A and the lower face 10B, including two opposite lateral faces 10C, 10D and two transverse faces. opposite 10E, 10F.

The upper face 10A has a trapezoidal cross-section, more generally an upward convex cross-section.

As a variant, the upper face 10A nevertheless has a geometry of any suitable type.

The lower face 10B is flat. However, it has a variant geometry of any suitable type.

The transverse faces 10E and 10F illustrated on the figure 1 are flat. Alternatively, particularly in the case of a molded interjoists, they are for example provided with male and / or female interlocking reliefs with a longitudinally adjacent interjoists. They generally have a geometry of any type suitable.

The interjoists present at each lateral end a lateral spoiler 12 bearing on a joist 4. The corresponding lateral face 10C, 10D delimits the lateral spoiler 12.

In the remainder of the description, "the spoiler" refers to each spoiler or spoiler if there is only one.

The spoiler 12 illustrated extends over the entire length of the interjoists 1. As a variant nevertheless, the spoiler 12 has for example a length less than that of the interjoists 1.

Note that we do not take into account, for the length of the interjoists, possible male reliefs present at the longitudinal ends to fit with adjacent interjoists.

The spoiler 12 has a substantially horizontal upper face 14, a face 16 of horizontal support on the joist 4, substantially vertical, and a lower face 18 of vertical support on the joist 4, substantially horizontal.

Alternatively, the spoiler 12 has a different geometry. This is, in general, a support spoiler 12 whose contour is of any type suitable for a vertical support on the joist 4.

A longitudinal groove 20 formed in the interjoists 1 over the entire length of the spoiler 12, defines two contiguous faces: the lower face 18 of the spoiler 12 and a horizontal support surface 22 on the joist 4, substantially vertical and located under the spoiler 12.

"Rebate" means a notch at right angles. In a variant, it is not a rabbet in the strict sense of the term but a wedge notch whose angle is obtuse or acute. In general, it is therefore a longitudinal cut in wedge, that is to say in triangular prism.

In its lower part, the interjoists 1 furthermore has a lower tongue 24 projecting laterally with respect to the lateral spoiler 12, and intended to be inserted under the support joist 4 on which said lateral spoiler bears, as the illustrates on the figure 1 .

Tab 24 provides insulation under the joist 4.

The tongue 24, as illustrated, is provided only on one side of the interjoists 1, to facilitate installation on the joists 4.

On the opposite side, the interjoists 1 advantageously have a female housing 26 for receiving the tongue 24 (see FIG. figure 3 for reference 26), for example formed as illustrated in Figures 1 to 6 by a rabbet under the face 22 of horizontal support, so as to ensure good insulation at the junction between the tongue 24 and interjoin laterally adjacent. For this purpose, the lower face 24B of the tongue 24 extends the lower face 10B of the central portion of the interjoists 1, which is flat. In addition, advantageously the upper face 24A and the face 24C of the tongue 24 are shaped to respectively contact the upper face 26A and the side face 26D of the female housing 26, preferably over their entire surface (see figure 1 ).

Alternatively, the interjoists do not have a female housing 26 and the tongue 24 is for example intended to extend facing the face 22 of horizontal support of the laterally adjacent interjoists.

Alternatively also, the interjoists do not have tab 24.

In general, however, the interjoists 1 has one or more open and non-traversing longitudinal slots 30 respectively extending from said lateral face 10C, 10D at the level of the horizontal support face 22 or under the face 22 of horizontal support, towards the interior of the body of the interjoists 1. The intervous central of the figure 1 has two. The intervent located on the right in the figure does not have, to better highlight the presence of the slots on the central interjoists.

In the presence of a tongue 24, as illustrated, the mouth of the or each slot 30 is at the tongue 24 or above the tongue 24 or, preferably, at the stop 32 (see reference on figure 3 ) formed at the junction of the tongue 24 and said face 22 of horizontal support of the rabbet 20, as realized in the examples of the Figures 1 to 6 .

On the Figures 2, 5 and 6 two slots 30 are provided with their mouths respectively on the side of the tongue 24 and the opposite side, more particularly extending along the edge 32 of the tongue 24 and following the edge 34 of the corner of the female housing 26.

As visible on the figure 1 the slots 30 extend along the entire length of the interjoists. They also open on the transverse faces 10E and 10F. Alternatively, however, the slots do not extend over the entire length of the interjoists but for example on only a part of the length of the interjoists. In general, the slots 30 are longitudinal, that is to say that their longitudinal extent is greater than their transverse extent. They are also longer than deep.

As also illustrated on the figure 1 the slots 30 illustrated are delimited by parallel faces of the interjoists. On the Figures 1 to 6 , the slots 30 are more particularly prisms, more particularly parallelepipeds rectangles for the Figures 1 to 4 .

On the Figures 3 and 4 , a slot 30 is provided only on the opposite side to the tab 24, more particularly with the mouth of the slot 30 following the stop 34 of the corner of the female housing 26.

In all the examples, the slots 30 have a width of 1mm.

The width of the slot is the distance between the longitudinal edges of the slot.

More generally, the or each slot 30 has for example but not necessarily a width less than or equal to 5mm.

The width of the slot 30 is for example, but not necessarily constant over its entire depth and / or length. Width means the maximum width of the slot.

In the examples of Figures 2 and 5 the two slots 30 have a depth of about 15cm. On the figure 3 , the slot has a depth of about 30cm. On the figure 4 , the depth is about 10cm while it is 15cm in the examples of figures 5 and 6 .

In general, the or each slot 30 has for example but not necessarily a depth of at least 2 cm, preferably at least 5 cm.

The depth of the slot 30 is for example, but not necessarily constant, over the entire length of the slot 30. Depth means the maximum depth.

On the figure 2 , the slots 30 have straight and horizontal cross sections, as well as the single slot 30 of the figure 3 .

Slot 30 of the figure 4 is of straight section and inclined with respect to the horizontal of approximately 45 °.

The two slots 30 of the figure 5 each have a proximal portion of cross section and horizontal. By "proximal" portion is meant a portion located near the mouth of the slot 30.

The or each slot 30 may also have a non-rectilinear cross section, as illustrated in FIG. figure 5 , whose slot 30 on the left in the figure has a portion of arcuate section.

As illustrated by the other slot 30 of the figure 5 and by the two slits of the figure 6 , the slot 30 may have different straight sections inclined together, including a horizontal straight proximal section ( figure 5 ) or tilted downwards ( figure 6 ), an intermediate section at 45 ° ( figure 5 ) and a horizontal distal straight section ( figure 5 ) or, for example, tilted upwards ( figure 6 ).

In general, the or each slot 30 has, for example, but not necessarily a portion of straight cross section, for example horizontal and / or for example proximal.

Note that a slot of right cross section corresponds to a pallelepiped slot in the case of a constant cross section of the slot 30 over its entire length.

In the case of a section of straight section, it is generally oriented with an angle between 0 ° and 60 ° inclusive terminals, relative to the horizontal.

In the case of the arcuate portion of the figure 5 Note that the local inclination at any point of the slot is between 0 ° and 60 °. This is generally a slot having a curved portion with a total inclination, for example at least one point, for example at any point, between 0 ° and 60 ° relative to the horizontal.

If two opposite slots are present, as on the Figures 2, 5 and 6 the slots 30 preferably have a substantially identical width and depth but are not necessarily symmetrical, as illustrated by FIG. figure 5 .

In general, the or each slot 30 has a geometry and a position adapted for an increase in the vertical load on the upper face 10A of the interjoists 1, in particular on the central portion of the upper face 10A, inducing a spacing of the opposite faces 10C, 10D of horizontal support when the interjoists 1 is supported on the joists 4.

The body of interjoists 1 is made of expanded polystyrene (EPS). More generally, it is a material of cellular plastic material of any suitable type, for example polyurethane (PU) or extruded polystyrene (XPS).

In general, the cellular plastic material has a density of between 10 and 50 kg / m ³ .

In a general manner also, the cellular plastic material has a Young's modulus of between 0.5 MPa and 10 MPa.

In the illustrated examples, the body of the interjoists is full, with the exception of the slots, that is to say that it has no other cavities than the slots. This is for example the case of an intervous obtained by cutting in a block.

Alternatively, however, for example in the case of obtaining by molding, cavities, for example longitudinal may be provided, for example in order to save material in the central portion of the interjoists.

The manufacturing process of interjoists Figures 1 to 6 will now be described.

Three possible formation processes of the body are, for example, cutting in a block of material, molding or extrusion.

Cutting, for example wire cutting, for example hot wire, is particularly advantageous in that it allows an embodiment of the or each slot for a relatively low additional cost. It is generally a cut of any suitable type, for example wire, oscillating wire, oscillating hot wire, saw, or by machining.

In the case of a molding, removable drawers are for example provided to be driven into the mold and thus ensure the formation of the slots and removed from the inside of the mold before demolding the interjoists to facilitate this demolding.

According to another aspect of the invention, it is a method of constructing a floor comprising a step of placing interjoists 1 on joists 4 to form a waterproof form, and a step pouring a concrete screed or a material of any type adapted to the formwork thus formed.

The or each vertical support face 18 of the interjoists 1 bears against a horizontal face of the corresponding joist 4 and the or each horizontal support face 20 positioned facing a vertical face of the same joist 4.

If there is a tab 24 on the interjoists, the tongue 24 of each interjoists 1 is configured to be contiguous with the identical interjoists laterally adjacent to the side of the tongue 24 (and of course with the possible longitudinal interjoists adjacent) so that the interjoists together delimit a substantially continuous underside under the joists 4.

TESTS

Compared the values of the Punching Punching Test Resistance (RPF) between interlinings without slots called "standard", and interjoists "with slots" differing from the "standard" interjoists only by the presence of slots as illustrated on the figure 2 .

The two slots are made by cutting the hot wire to a depth of about 150mm and with a width of 3 to 4 mm.

Twenty-four interjoists, twelve of which were "standard" and twelve "with slits" were cut from the same block of expanded polystyrene, the "standard" in the lower half of the block and the "with slits" in the upper half.

• 2 x 4 entrevous (bas / haut) extrémité 1 du bloc:
  • B1 h1, B1 h2, B1 h3, B1 h4, B1 b1, B1b2, B1b3 et B1b4
• 2 x 4 entrevous ( bas / haut ) partie centrale du bloc :
  • Mh1, Mh2, Mh3, Mh4, Mb1, Mb2, Mb3 et Mb4
• 2 x 4 entrevous ( bas / haut ) extrémité 2 du bloc :
  • B2h1, B2h2, B2h3, B2h4, B2b1, B2b2, B2b3 et B2b4

Sampling is carried out along the length of the block, divided into three parts, two longitudinal end parts and a central part:

• 2 x 4 interjoists (low / high) end 1 of the block:
  • B1 h1, b1 h2, b1 h3, b1 h4, b1 b1, b1b2, b1b3 and b1b4
• 2 x 4 interjoists (low / high) central part of the block:
  • Mh1, Mh2, Mh3, Mh4, Mb1, Mb2, Mb3 and Mb4
• 2 x 4 interjoists (low / high) end 2 of the block:
  • B2h1, B2h2, B2h3, B2h4, B2b1, B2b2, B2b3 and B2b4

• la détermination de la masse volumique ; et
• des essais de poinçonnement-flexion sur un appareil CTI

The tests focused on:

• determination of the density; and
• punch-bending tests on a CTI device

(Hydraulic testing machine marketed by the company 3R)

Density measurement is intended to help ensure that "slotted" interjoists are at least as strong as "standard" interjoists with the same or lower density.

Previous tests had shown that interjoists "with slots" were more resistant but the results difficult to interpret in a safe way because the interjoists "with slots" had a higher density.

The density was lower here in the lower half of the block.

For testing, each tab was cut. This has no influence on the interpretation that can be made of the results.

The application of the force was 10daN / s and the rupture detection at 30%.

The results are shown in Table 1 below. Table 1 Ref. Profile MV (g / l) RPF (daN) breaking b1b1 standard 17.71 115.2 spoiler B1h1 With slots 16.99 156.3 under face b1b2 standard 17.35 105.2 spoiler B1h2 With slots 16.43 146.2 under face B1b3 standard 17.40 124.4 spoiler B1h3 With slots 16.29 122.3 spoiler B1b4 standard 17.83 107.2 spoiler B1h4 With slots 16.73 129.2 under face Mb1 standard 17.50 103.9 spoiler mh1 With slots 16,15 132.1 under face Mb2 standard 17.43 105.0 spoiler Mh2 With slots 16,12 129.6 under face mb3 standard 17.39 103.4 spoiler mh3 With slots 16.19 131.1 under face mb4 standard 17.57 108.7 spoiler mh4 With slots 16.16 129.5 under face B2B1 standard 17.42 116.4 spoiler B2h1 With slots 17.33 154.3 under face b2b2 standard 17.16 127.5 spoiler 2h2 With slots 16.77 137.7 under face B2b3 standard 17.14 135.7 spoiler B2h3 With slots 16.64 137.7 under face B2b4 standard 17.23 106.0 spoiler B2H4 With slots 16.57 137.5 under face

Note that an "underside" break means a break in the central part of the interjoists, the primer is for example at the distal end of the slot or close.

Average resistance and average density are calculated for each type of interjoists in Table 2 below. Table 2 RPF average standard profile (daN) 113.2 MV moy = 17.43 RPF average profile with slots (daN) 137.0 MV moy = 16,53

The standard deviation for the RPF resistance is about 10. The breaking strength deviations are therefore significant from a statistical point of view.

In addition, it can be seen that the minimum resistance is clearly increased in the interjoists "with slots", despite a lower density of interjoists with "slots" that were the subject of these tests.

When compared to the density, the relative difference between the breaking strength of the "standard" interjoists and the breaking strength of the "slotted" interjoists is even greater.

The Figures 7 and 8 illustrate the validation of these results by 2D finite element numerical computation (realized with the Acord 2D software, with the plane deformation assumption, validated by preliminary 3D calculation). The figure 7 corresponds to a "standard" interview and the figure 8 at an interview with "slits".

• une diminution de la concentration de contraintes sur la jonction béquet-face d'appui horizontal ;
• une augmentation de la concentration de contraintes sur la face d'appui horizontal, allégeant ainsi la charge sur le béquet
• une concentration de contraintes à l'extrémité distale de la fente, amorce de rupture et justifiant ainsi le nouveau profil de rupture observé.

We observe :

• a decrease in the concentration of stresses on the horizontal spur-face junction;
• an increase in the stress concentration on the horizontal support face, thus relieving the load on the spoiler
• a concentration of stresses at the distal end of the slit, initiating rupture and thus justifying the new observed rupture profile.

Claims (11)

1. Floor formwork structural floor unit (1), the body of which is made of cellular plastic material, the structural floor unit (1) being delimited by a top face (10A), a bottom face (10B) and four faces (10C, 10D, 10E, 10F) joining the top face (10A) and the bottom face (10B), including two opposing transverse faces (10E, 10F) and two opposing lateral faces (10C, 10D), at least one of the lateral faces (10C, 10D) delimiting a lateral spoiler (12) of the structural floor unit bearing vertically on a supporting joist (4), the structural floor unit (1) having, on the or each lateral face (10C, 10D) delimiting a lateral bearing spoiler (12), a wedge-shaped longitudinal notch (20), for example a right-angled notch, forming two contiguous faces:

   - a face (18) bearing vertically on the corresponding supporting joist (4) and delimiting the bottom part of the respective lateral bearing spoiler (12); and

   - under the lateral bearing spoiler (12), a face (22) bearing horizontally on the same supporting joist (4),

   characterized in that the structural floor unit (1) has, for the or each lateral face delimiting a lateral bearing spoiler, at least one open and non-through internal longitudinal slot (30) extending respectively from said lateral face at the level of the bottom part of the horizontally bearing face (22) or under the horizontally bearing face (22), towards the interior of the body of the structural floor unit (1).
2. Structural floor unit (1) according to Claim 1, in which the or each slot (30) has a geometry and a position that are suitable for an increase in the vertical load on the top face (10A) of the structural floor unit (1), notably on the central portion of the top face (10A), to induce a separation of the opposing horizontally bearing faces (22) when the structural floor unit (1) is bearing on the supporting joists (4).
3. Structural floor unit (1) according to Claim 1 or 2, in which the or each slot (30) has a portion with at least one local inclination that is between 0° and 60° relative to the horizontal, for example a slot of curved or straight-line cross section.
4. Structural floor unit (1) according to any one of the preceding claims, in which the or each slot (30) is open over a width less than or equal to 5 mm.
5. Structural floor unit (1) according to any one of the preceding claims, in which the or each slot (30) is open to a maximum depth of at least 20 mm, preferably to a depth of at least 50 mm.
6. Structural floor unit (1) according to any one of the preceding claims, in which the structural floor unit (1) has a tongue (24) protruding laterally relative to the corresponding lateral spoiler (12), and intended to be inserted under the supporting joist (4) on which said lateral spoiler (12) bears.
7. Structural floor unit (1) according to Claim 6, in which the mouth of the or each slot (30) is at the level of the tongue (24) or above the tongue (24) or preferably at the level of the edge (32) formed at the junction of the tongue (24) and of said horizontally bearing vertical face (22), on the side of the tongue (24) and/or on the side opposite the tongue (24).
8. Method for manufacturing a floor formwork structural floor unit (1) according to any one of the preceding claims.
9. Method for manufacturing a structural floor unit (1) according to Claim 8, in which the or each slot (30) is cut in the body of the structural floor unit (1), for example by means of a wire.
10. Method for constructing a floor comprising a step of installing structural floor units (1) on supporting joists (4) to form a tight formwork, and a step of pouring a concrete screed onto the duly formed formwork, in which at least some of the structural floor units, for example all the structural floor units, are according to the preamble of Claim 1 and are characterized in that they have, for the or each lateral face delimiting a lateral bearing spoiler (12), at least one open and non-through internal longitudinal slot (30) extending respectively from said lateral face at the level of the horizontally bearing face (22) or under the horizontally bearing face (22), towards the interior of the body of the structural floor unit (1).
11. Method according to Claim 10, in which at least some of the structural floor units, for example all the structural floor units, are according to any one of Claims 1 to 7.

Images