Title: Reinforced-connection member joining a connector and a concrete wall and associated building panel

[0001] The invention falls within the field of construction and relates more particularly to the connecting elements used in building panels.

[0002] In the building or construction industry, double-walled building panels, known as sandwich panels, comprising two concrete walls facing one another and separated by a space into which thermal insulation materials are incorporated to avoid heat loss, are known. The connection between the concrete walls of the sandwich panels is achieved by connectors partially embedded in the concrete of the two walls. These connectors are metal or composite-material reinforcements generally of wavy shape the crests or peaks of which are embedded in the concrete.

[0003] In order to reduce the weight and the thickness of sandwich panels, the external or exterior wall, which is to say the wall that is to be on the outside of the building built with such panels, is made from a high-performance fibre-reinforced or reinforced concrete characterized by a high compression strength, which is to say one in excess of 100 MPa. Such concrete makes it possible to reduce the thickness of this external wall to a few centimetres.

[0004] Nevertheless, because of the small thickness of the external wall, only the end part of the connectors is embedded in the concrete. Thus, the pull-out strength or shear strength of the connectors is lower, entailing the use of a significant number of connectors in order to ensure a sufficiently firm connection between the two walls of the sandwich panel.

[0005] In order to mitigate the various disadvantages mentioned above, the invention aims to provide a system that makes it possible to ensure the structural strength of a sandwich panel and to do so whatever the type of concrete used for the walls thereof.

[0006] To this end, the invention relates to a reinforced-connection member joining a concrete wall and a connector, which member is intended to be embedded in the concrete wall, has a main axis and comprises:

• an anchor plate having an external planar face intended to face the exterior face of the concrete wall, and • a housing body projecting from the anchor plate on the opposite side to its external face, which housing body comprises a through-housing for receiving an end portion of the connector which extends along the main axis of the connection member and which opens onto said external face, and fixing means for fixing said connector end portion in said through-housing.

[0007] The connection member of the invention thus offers a dual function: fixing an end portion of the connector to said member, and increasing the area of contact with the concrete wall, thereby improving the pull-out strength and the ability to resist shear force.

[0008] The reinforced-connection member may also comprise the following optional features considered alone or in any technically possible combinations:

The main axis forms the main axis of symmetry of the reinforced-connection member.

The reinforced-connection member comprises distance-maintaining elements for keeping the anchor plate distant from the exterior face of the concrete wall, which distance-maintaining elements project from the external face of said anchor plate.

The anchor plate comprises two flanges which extend one on each side of the housing body and of the main axis of symmetry, and the smallest width of each flange is at least equal to the width of the through-housing.

The anchor plate comprises at least two symmetrical feet which extend one on each side of the housing body from said housing body.

The anchor plate comprises four feet distributed in pairs symmetrically one on each side of the housing body.

Each foot has at least one through-opening.

The housing has a convex curvature intended to match the curvature of the connector portion.

The housing body has a U-shaped cross section, and the fixing means formed at the through-housing are means of attachment through elastic engagement.

[0009] The invention also relates to a reinforced-connection device for a building panel of the sandwich panel type, comprising a connector of wavy shape comprising a plurality of peaks and at least one reinforced-connection member as described hereinabove arranged at a peak, which forms a connector end portion fixed in the housing of said connection member.

[0010] The reinforced-connection device may also comprise the following optional features considered alone or in any technically possible combinations:

The connector is made of composite material.

[001 1] The invention also relates to a building panel which comprises a concrete interior wall and a concrete exterior wall which are positioned facing one another, the exterior wall comprising an interior face facing the interior wall and an opposite exterior wall, which panel comprises a layer of thermal insulation material placed between the two concrete walls and at least one reinforced-connection device as described hereinabove connecting the two walls and keeping them distant from one another, which reinforced-connection member is embedded in the exterior concrete wall, the external face of its anchor plate facing the exterior face of the concrete wall concerned. [0012] The invention also relates to a method for joining a connection device as described hereinabove to a concrete wall, comprising the successive steps of:

• Inserting at least one peak-forming end portion of the connector into the housing(s) of the reinforced-connection member concerned so as to form the connection device, each reinforced-connection member comprising a plurality of positioning elements for positioning the member in the concrete wall;

• Placing the connection device in a concrete-wall mould, the positioning elements being in contact with the bottom of the mould;

• Pouring concrete into the mould so as to completely cover the reinforced- connection member(s), and

• Drying the poured concrete to form a concrete wall in which the connection members of the connection device are embedded.

[0013] Further features and advantages of the invention will become clearly apparent from the description thereof given hereinbelow, by way of entirely nonlimiting indication, with reference to the attached figure:

[0014] [Fig 1 ] Figure 1 depicts a view in cross section of a building panel comprising a connection device of the invention.

[0015] [Fig 2] Figure 2 depicts a perspective view, from above, of the reinforced- connection member according to the invention. [0016] [Fig 3] Figure 3 depicts a perspective view, from below, of the reinforced- connection member according to the invention.

[0017] [Fig 4] Figure 4 depicts a side view of the reinforced-connection member according to the invention.

[0018] [Fig 5] Figure 5 depicts a side view, from another side, of the reinforced- connection member according to the invention.

[0019] [Fig 6] Figure 6 depicts a view, from above, of the reinforced-connection member according to the invention.

[0020] It must first of all be emphasised that, in the figures, the same references denote the same elements whatever the figure in which they appear and however such elements are embodied. Likewise, if elements are not specifically referenced in one of the figures, their references can easily be deduced by reference to another figure.

[0021] It is also emphasised that the figures essentially depict one embodiment of the subject matter of the invention, but that there may be other embodiments that meet the definition of the invention.

[0022] With reference to Figure 1 , the invention relates to a building panel known as a sandwich panel 15, which comprises two concrete walls 2, 16 facing one another and connected to one another via connection means, as well as a layer of thermal insulation 17 placed between the two concrete panels 2, 16.

[0023] One of the walls, referred to as the external or exterior wall 2, because it is intended to face towards the outside of the building constructed using such sandwich panels 15, is made of high-performance fibre-reinforced or reinforced concrete having a compression strength of the order of 100 MPa. This external wall 2 has a thickness of the order of 3 cm and in fact contributes to the lightness in weight of the sandwich panel 15.

[0024] The other wall, referred to as internal or interior wall 16, because it is intended to face towards the inside of the building, is made from a lightweight concrete having a density of between 800 kg/m ³ and 1300 kg/m ³ , and which has a compression strength of between 12 and 20 MPa. As a preference, the lightweight concrete has a density of the order of 1000 kg/m ³ and a compression strength of the order of 16 MPa. This internal wall 16, which has a thickness of the order of 15 cm, provides the structural integrity of the sandwich panel 15 while at the same time limiting the weight thereof. [0025] With reference to the figures, the means of connection that connect the two walls 2, 16 to one another comprise a plurality of connection devices 11 according to the invention.

[0026] Each connection device 11 comprises a connector 3 which is depicted in its entirety in Figure 1. Nonlimitingly, this connector 3 is a reinforcement made of composite material comprising glass fibres reinforced with polymer resins, for example resins based on vinyl esters. Moreover, the connector 3 has a wavy periodic shape, preferably a sinusoidal shape, as indicated in Figure 1. Alternatively and without departing from the scope of the invention, the wavy connector 3 may have a period of some other shape, for example trapezoidal, or in other words may be a sinusoid with clipped peaks.

[0027] The period of the connector 3 is defined by the pattern between two facing peaks 14. Moreover, the height of the connector 3 is defined as being the peak to peak amplitude of the connector 3.

[0028] In order to connect the two concrete walls 2, 16 with one another, end portions of the connector 6 comprising these peaks are embedded in said concrete walls 2, 16. In fact, the height of the connector 3 is greater than the thickness of the layer of insulating material 16 of the sandwich panel 15.

[0029] Nevertheless, because the thickness of the high-performance concrete external wall 2 is relatively small, it is necessary to reinforce the connection between said external wall 2 and the connector 3.

[0030] According to the invention, each connection device 11 comprises at least one, and preferably a plurality of, reinforced-connection member(s) 1 depicted in detail in Figures 2 to 6. Each reinforced-connection member 1 is fixed to the connector portion 6 embedded in the concrete wall 2 - which connector portion 6 comprises the relevant peak of the connector 3 - so that said connection member 1 is embedded in the concrete of the external wall 2.

[0031] The connection member 1 , which is preferably made from a polymer-based material, preferably glass-fibre reinforced, is a component exhibiting two mutually perpendicular axes of symmetry X and Y, these axes being indicated in Figures 3 to 6. Moreover, the connection member 1 extends along the axis of symmetry X which also forms a longitudinal axis, the axis of symmetry Y in fact forming a transverse axis.

[0032] The connection member 1 comprises a housing body 4 which itself comprises a through-housing 5 which extends along the longitudinal axis X, the housing body 4 having a U-shaped cross section: the housing body 4 thus comprises a bottom wall and two lateral walls. Alternatively and without departing from the scope of the invention, the through-housing 5 could extend along the transverse axis Y, the essential thing being that this housing 5 needs to extend along an axis of symmetry of the connection member 1 .

[0033] The edges 20 of the housing 5 are defined by the edges of the lateral walls of the housing body 4, which housing 5 is intended to receive a portion of the connector 6 that comprises a peak of the connector 3. For improved connection of the relevant peak in the housing 5, the latter has the same cross section as the connector 3, and a convex curvature that matches the curvature of the peak housed in said housing 5.

[0034] The symmetrical positioning of the through-housing 5 means that the mechanical forces generated at the connection between the connector 3 and the external wall 2 of the sandwich panel 15, when the connection member 1 is fixed to the connector 3 and embedded in the relevant concrete wall 2, can be distributed evenly.

[0035] Finally, the housing body 4 comprises fixing means 12 for fixing the peak into the housing 5 by elastic engagement, or clip-fastening, these means being formed at the edges 20 of the lateral walls of the housing body 4.

[0036] The connection member 1 further comprises an anchor plate 24 which has an external face 9 which is intended to face the exterior face of the external concrete wall 2. What is meant by the external face 9 is the face onto which the housing 5 opens, the internal face being the opposite face.

[0037] The anchor plate 24 further has two flanges 13 which extend one on each side of the housing 5 in a plane defined by the axes of symmetry X and Y. More specifically, the two flanges 13 extend from the edges 20 of the lateral walls of the through-housing 5. The housing body 4 further comprises two reinforcers 21 perpendicular to the flanges 13, each one secured to one of the legs of the U-shaped housing 5 and to the internal face of the relevant flange 13, these reinforcers 21 improving the rigidity of the flanges 13.

[0038] The main body 4 has a quadrilateral overall shape with curved longitudinal edges 25, and the minimum width L1 of each flange 13 is at least equal to the width L2 of the through-housing 5. The area of contact between the concrete external wall 2 and the connection member 1 is thus far greater than the area of contact between the connector 3 alone and the external concrete wall 2, thereby increasing the pull-out strength of the connection device 11 with said concrete wall 2.

[0039] In order to increase still further the area of contact of the connection member 1 with the concrete wall 2, the anchor plate 24 comprises four feet 7 which extend in pairs on each side of the through-housing 5 and symmetrically with respect to the two axes of symmetry X and Y, again in order to conform to the distribution of forces at the connections between the connection devices 1 1 and the relevant concrete wall 2. More specifically, the feet extend from the four corners 26 of the respective flanges 13.

[0040] Each foot 7 thus extends from the main body 4 as far as a disc-shaped free end 23 so as to further increase the area of contact between the connection member 1 and the external concrete wall 2, and thereby increase the pull-out strength. Furthermore, each foot 7 comprises a through-opening 8 which improves the distribution of the concrete around the feet 7 and improves the anchorage of the connection member 1 in the concrete external wall 2.

[0041] Finally, each foot 7 comprises a reinforcer 22 perpendicular to the plane defined by the axes X and Y, which reinforcer 22 is secured to the through-housing 5 and to the internal face of the relevant leg 7, these reinforcers 22 improving the stiffness of the legs 7. As may be seen in Figures 2, 3 and 6, each opening 8 is delimited by the relevant corner 26 of the relevant flange 13, the edge of the relevant disc 23 and the lateral edges 27 of the foot 7, one of said lateral edges 27 being secured to the relevant reinforcer 22.

[0042] According to the invention and with reference to Figures 3 to 6, the anchor plate 24 has a planar external face 9 parallel to the plane defined by the axes X and Y. Thus, the external faces of the flanges 13 and of the feet 7 all lie in the same plane. Further, and as depicted in Figures 3 to 5, the connection member 1 comprises a plurality of positioning elements 10 for positioning the connection member 1 in the relevant concrete wall 2, which elements 10 are conical projections projecting from the planar external face 9 of the anchor plate 24. Moreover, all these positioning elements 10 are identical and the same size.

[0043] The positioning elements 10 allow the planar external face 9 of the anchor plate 24 to be positioned at a determined distance from the exterior face of the concrete external wall 2, this distance being equal to the height of the cones that form the positioning elements 10. Moreover, because all of the cones 10 are identical, the planar external face 9 of the anchor plate 24 is parallel to the external face of the concrete external wall 2 in which the connection member 1 is embedded, thereby evening out the distribution of the pull-out forces and improving the pull-out strength of the connection devices 11 . The external face of the external wall 2 is the face intended to face towards the outside of a building constructed using the sandwich panels 15 of the invention.

[0044] A method for manufacturing a sandwich panel 15 according to the invention will now be described.

[0045] During the course of a first step, at least part of the peaks of each connector 3 concerned is fixed to at least one reinforced-connection member 1 . More specifically, the connector portions 6 comprising the peaks are inserted into the housings of the housing bodies 4 of the relevant connection members 1 and fixed into said housings 5 by elastic engagement. At the end of this step, a plurality of connection devices 11 has been created.

[0046] During the course of a second step, these connection devices 11 are placed in the bottom of a concrete mould. More specifically, the planar external faces 9 of the anchor plates 24 of the connection members 1 of each connection device 11 face towards the bottom of the mould, and the positioning cones 10 are in bearing contact against the bottom of the mould.

[0047] During the course of a third step, high-performance concrete is poured into the mould so as to embed the reinforced-connection members 1 in the wet concrete. Once the concrete has dried, connection devices 11 that are set in the external concrete wall 2 to form an exterior portion of the building panel 18 are obtained.

[0048] During the course of a fourth step, a layer 16 of insulation is placed against the internal face of the concrete external wall 2. Those parts of the connectors that are not embedded in the external wall 2 are thus inserted into the layer 16 of insulation, with the exception of the free peaks 14 of said connectors 3.

[0049] During the course of a fifth step, the exterior panel portion 18 is placed in a second mould, with the free peaks 14 of the connectors 3 in bearing contact with the bottom of this second mould.

[0050] During the course of the sixth step, lightweight concrete is poured into the mould so as to form, after drying, the internal wall 16 of the building panel 15.

[0051] The reinforced-connection member 1 and the connection device 1 1 of the invention thus make it possible to create concrete building panels 15 of the sandwich panel type that are particularly well able to withstand the pull-out forces and shear forces experienced by the connectors 3, even when the concrete wall or walls 2 of the panel 15 are of small thickness, typically of the order of 3 centimetres thick.

[0052] The embodiment described hereinabove is entirely nonlimiting, and modifications may be made thereto without departing from the scope of the invention. By way of example, the reinforced-connection member does not necessarily have an axis of symmetry, but may simply have a main axis forming, for example, the longitudinal axis of said reinforced-connection member according to the invention.