FR3057290A1 - FORMWORK SYSTEM, BONDING MEMBER ESPECIALLY ADAPTED FOR SUCH A FORMWORK SYSTEM AND METHOD FOR PRODUCING A SLAB OF A BUILDING USING SUCH A FORMWORK SYSTEM - Google Patents

Abstract

Shuttering system (17) for producing a hopper in a slab of a building, comprising: - at least two shuttering walls (18), - at least two connecting members (25) configured to bond the shuttering walls (18). ) to each other so as to form a formwork (15), each of the connecting members (25) comprising: - a fixing portion (26) configured to be fixed to wall portions of at least two formwork walls (18), - a reservation part (35) extending along a reservation axis (R) parallel to the form axis (C), away from the fixing part (26), the reservation part ( 35) being arranged at a distance and facing a portion of outer surfaces (18b) of the formwork walls (18).

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number:

(to be used only for reproduction orders)

©) National registration number

057290

59694

COURBEVOIE © Int Cl ⁸ : E 04 G 15/06 (2017.01)

PATENT INVENTION APPLICATION

A1

©) Date of filing: 07.10.16. (© Applicant (s): B @ TIROC-PROTECT Company by (© Priority: simplified actions - FR. @ Inventor (s): HAVYARIMANA GELASE. ©) Date of public availability of the request: 13.04.18 Bulletin 18/15. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): B @ TIROC-PROTECT Company by related: simplified actions. ©) Extension request (s): © Agent (s): CABINET PLASSERAUD.

FR 3 057 290 - A1

(□ 4) FORMWORK SYSTEM, CONNECTING MEMBER SPECIFICALLY SUITABLE FOR SUCH A FORMWORK SYSTEM AND METHOD FOR MAKING A SLAB OF A BUILDING IMPLEMENTING SUCH A FORMWORK SYSTEM.

©) Formwork system (17) for making a hopper in a slab of a building, comprising:

- at least two formwork walls (18),

- at least two connecting members (25) configured to link the formwork walls (18) to each other so as to form a formwork (15), each of the connecting members (25) comprising:

a fixing part (26) configured to be fixed on wall portions of at least two formwork walls (18),

- a reservation part (35) extending along a reservation axis (R) parallel to the formwork axis (C), at a distance from the fixing part (26), the reservation part (35) being arranged spaced apart and facing a part of the outer surfaces (18b) of the formwork walls (18).

i

Formwork system, connecting member specially adapted for such a formwork system and method for producing a slab of a building using such a formwork system

The invention relates to a formwork system, to a connecting member specially adapted for such a formwork system and to a method for producing a slab of a building implementing such a formwork system.

In particular, the invention applies to the production of a hopper in a slab of a building. The hopper constitutes an opening used in particular to set up a staircase or elevator or to pass conduits or power cables.

It is known to produce a hopper during the formation of the slab, for example, by pouring a material from which the slab is made in the fluid state around a formwork. Formwork is generally obtained from a formwork system of the type comprising:

- two or more of two formwork walls each having opposite inner and outer surfaces,

- Two or more of two connecting members configured to, in an assembled state of the formwork system, link the formwork walls to each other.

In a construction, renovation or other site, it is necessary to secure the hoppers provided in the slabs of a building against the risk of falling.

Depending on the dimensions of the hoppers, different security systems are used.

For large hoppers, notably between 1.5 m x 1.5 m and 2.5 m x 2.5 m, intended in particular to receive stairwells or elevator shafts, podiums are generally used. The podiums include longitudinal members, adjustable in length, extending into the hopper and covered with decking, and uprights, adjustable in height, supporting the longitudinal members and adapted to bear on a lower slab. However, such podiums are not suitable for smaller hoppers and their installation, generally requiring the intervention of a crane, is long and difficult.

For smaller hoppers, platforms are generally used. The platforms consist of side rails mounted on the edges of the hopper and covered with decking, or one or more boards laid on the slab to cover the hopper. However, such platforms, which can undergo a significant number of manipulations or be moved inadvertently, do not offer reliable security throughout the duration of the work.

There is therefore a need to reliably secure a hopper regardless of the dimensions of the hopper.

The invention aims to meet this need.

To this end, according to a first aspect, the invention proposes a formwork system of the aforementioned type in which each of the connecting members comprises:

- a fixing part configured to be fixed on wall portions of at least two formwork walls in the assembled state of the formwork system,

a reservation part extending along a reservation axis parallel to the formwork axis, at a distance from the fixing part, the reservation part being arranged at a distance and facing a part of the external surfaces of the walls of formwork in the assembled state of the formwork system so as to be able to form a reservation hole in the slab at a distance from the hopper.

Thus, the invention makes it possible to obtain reservation holes arranged in a simple and reproducible manner directly on the slab, during its formation, in locations previously occupied by the reservation parties. These reservation holes allow the mounting of a railing offering reliable security and adaptable to the dimensions of the hopper.

The reservation part may include a cylindrical rod along the reservation axis.

The reservation part may further comprise a cylindrical sleeve along the reservation axis fitted removably on the rod.

Each formwork wall may have a length between two opposite transverse edges, the wall portions of each formwork wall being formed respectively in the vicinity of the transverse edges, and the fixing part of each connecting member may form an angle iron comprising two plates forming an angle around a fixing axis, in particular a right angle, each of the angle plates being fixed to the wall portion of one of the formwork walls in the assembled state of the formwork system.

The fixing part of each connecting member can have a height measured along the fixing axis and opposite internal and external surfaces, the reservation part being arranged facing the external surface of the fixing part, the external surface of the fixing part being in contact with the wall portions.

Each formwork wall can have a height between opposite lower and upper lateral edges, the fixing part of each connecting member extending along the fixing axis between opposite lower and upper ends, the lower end of the part fixing means being provided with a lower wing extending perpendicular to the fixing axis in a direction opposite to the reservation part, the lower ends of the fixing parts being coplanar with the lower lateral edges of the formwork walls and the wings lower fixing parts extending into the hopper opening in the assembled state of the formwork system.

The formwork system may further comprise at least one reinforcing device comprising:

a reinforcing wall having a length between two opposite transverse edges, and

- two reinforcing members configured to each support one of the transverse edges of the reinforcing wall and to be mounted respectively on two formwork walls so that, in the assembled state of the formwork system, the reinforcing wall s extension in the hopper opening transversely to the formwork axis, in which each of the reinforcing members comprises:

- a fixing part configured to be fixed on the formwork wall in the assembled state of the formwork system,

a reservation part extending along a reservation axis parallel to the formwork axis, at a distance from the fixing part, the reservation part being arranged at a distance and facing a part of the external surface of the formwork wall in the assembled state of the formwork system so as to be able to form a reservation hole in the slab at a distance from the hopper.

According to a second aspect, the invention relates to a connecting member specially adapted for a formwork system as defined above, the connecting member being configured to, in an assembled state of the formwork system, link formwork walls together to the others so as to form a shuttering having a closed contour around a hopper opening along a shuttering axis, internal surfaces of the shuttering walls delimiting the hopper opening, the connecting member comprising:

- a fixing part configured to be fixed on wall portions of at least two formwork walls in the assembled state of the formwork system,

a reservation part extending along a reservation axis parallel to the formwork axis, at a distance from the fixing part, the reservation part being arranged at a distance and facing a part of the external surfaces of the walls of formwork in the assembled state of the formwork system so as to be able to form a reservation hole in the slab at a distance from the hopper.

According to a third aspect, the invention relates to a method for producing a slab of a building comprising a hopper, the production method implementing a formwork system as defined above and providing for:

- mount a suitable structure to support the slab,

- form a formwork with a closed contour around a hopper opening along a formwork axis by putting the formwork system in the assembled state, connecting members connecting the formwork walls to each other, a fixing part of each connecting member being fixed to wall portions of at least two shuttering walls, a reservation portion of each connecting member being arranged at a distance and facing a portion of the outer surfaces of the shuttering walls, interior surfaces of shuttering walls defining a hopper opening along the shuttering axis,

- form the slab on the structure and around the formwork,

- Remove the formwork, the slab having a hopper and reservation holes in locations previously occupied by the reservation parts of the connecting members.

The production method may also provide for mounting a bodyguard around the hopper, the bodyguard comprising posts mounted in the reservation holes and sleepers mounted on the posts.

Other objects and advantages of the invention will appear on reading the following description of a particular embodiment of the invention given by way of non-limiting example, the description being made with reference to the accompanying drawings in which :

- Figure 1 is a perspective representation of a formwork system for making a hopper in a slab of a building according to one embodiment of the invention, the formwork system comprising four formwork walls linked to each other by four connecting members so as to form a formwork defining a hopper opening, and a reinforcing device comprising a reinforcing wall mounted in the hopper opening on two shuttering walls by means of two reinforcing members,

- Figure 2 is a perspective view in top view of one of the connecting members of the formwork system of Figure 1, the connecting member comprising a fixing part in the form of an angle iron configured to be fixed on wall portions of two shuttering walls, and a reservation part comprising a rod and a sleeve fitted removably on the rod, the reservation part being intended to form a reservation hole in the slab at a distance from the hopper,

FIG. 3 is a perspective view from below of the connection member in FIG. 2,

- Figure 4 is an elevational representation of the connecting member of Figure 2,

FIG. 5 is a perspective view from above of one of the reinforcing members of the formwork system of FIG. 1, the reinforcing member comprising a fixing part configured to be fixed to the formwork wall, and a reservation part comprising a rod and intended to form a reservation hole in the slab at a distance from the hopper,

FIG. 6 is a perspective view from below of the reinforcement member of FIG. 5,

- Figure 7 is an elevational representation of the reinforcement member of Figure 5,

- Figures 8 to 13 are representations of steps of a method of producing a slab of a building comprising a hopper, illustrating in particular a formation of the slab around the formwork formed by the formwork system of Figure 1 and mounting a railing around the hopper in the reservation holes in locations previously occupied by the reservation parts of the connecting members and the reinforcing members.

In the figures, the same references designate identical or analogous elements.

FIG. 1 represents a formwork 15 for making a hopper 3 in a slab 2 of a building 1. The formwork 15 has a closed contour around a hopper opening 16 along a formwork axis C.

In the embodiment shown, the outline is rectangular and the formwork 15 is obtained from a formwork system 17 comprising four formwork walls 18 and four connecting members 25 configured for, in an assembled state of the formwork system 17 , link the formwork walls 18 to each other.

In the embodiment shown, each formwork wall 18 is constituted by a rectilinear board made of a suitable material such as wood. Each formwork wall 18 has inner 18a and outer 18b surfaces opposite and connected to each other by two opposite transverse edges 19 defining a length of the formwork wall 18, and by two lower side edges 20 and upper 21 defining a height of the formwork wall 18. The length of two of the formwork walls 18 is less than that of the other two formwork walls 18 to form the rectangular outline

In FIGS. 2 to 4, each connecting member 25, made of metal or any other suitable material, has a fixing part 26 configured to be fixed to wall portions of two formwork walls 18 in the assembled state of the system formwork 17. In particular, the fixing part 26 forms an angle iron comprising two plates 27 at right angles around a fixing axis F. The fixing part 26 has an internal surface 26a forming a concavity around the axis of attachment F, and an outer surface 26b opposite the inner surface 26a. The fixing part 26 also has a height measured along the fixing axis F between opposite lower 28 and upper 29 ends. The lower end 28 of the fixing part 26 is provided with a lower wing 30 which extends perpendicular to the fixing axis F in the concavity of the internal surface 26a. The upper end 29 of the fixing part 26 is provided with an upper wing 31 which extends perpendicular to the fixing axis F in a direction opposite to the concavity of the internal surface 26a and to the lower wing 30 In the figures, the fixing part 26 is produced from an assembly, in particular by welding, of metal sheets. In particular, two metal sheets are each folded to form one of the plates 27 adjoining on the one hand to a lower wing half 30 and on the other hand to an upper wing half 31, then welded.

Each connecting member 25 also includes a reservation part 35 extending along a reservation axis R parallel to the fixing axis F, at a distance and facing the external surface 26b of the fixing part 26. In particular, the reservation part 35 comprises a cylindrical rod 36 along the reservation axis R which extends from the upper wing 31, facing a corner where the plates 27 of the fixing part 26 meet. The rod 36 of the reservation part 35 is arranged at a distance dl from the external surface 26b of the fixing part 26 and has a length LI measured along the reservation axis R and a diameter Dl measured perpendicular to the reservation axis R. The reservation part 35 further comprises a cylindrical sleeve 37 along the reservation axis R, for example made of plastic, fitted removably on the rod 36. The sleeve 37 has a length 1 measured along the reservation axis R between a top end ieure 38 open by which a free end of the rod 36, opposite the upper wing 31, is inserted into the sleeve 37, and a lower end 39 closed. The sleeve 37 also has an inside diameter corresponding to the diameter of the rod 36 and an outside diameter De.

For each connecting member 25, the outer surface 26b of one of the plates 27 of the fixing part 26 is brought into contact with the inner surface 18a of the wall portion formed in the vicinity of one of the transverse edges 19 of one of the formwork walls 18 of great length, and the external surface 26b of the other plate 27 of the fixing part 26 is brought into contact with the internal surface 28a of the wall portion formed in the vicinity of one transverse edges 19 of one of the short formwork walls 18. The connecting members 25 and the formwork walls 18 are arranged in such a way that the lower ends 28 and the lower wings 30 of the fixing parts 26 are coplanar with the lower lateral edges 20 of the formwork walls

18. The plates 27 of the fixing part 26 are then fixed by any appropriate means, and in particular by screwing, respectively to the wall portions to put the formwork system 17 in the assembled state and form the formwork 15, the surfaces interior 18a of the formwork walls 18 and the internal surfaces 26a of the fixing parts 26 of the connecting members 25 delimiting the hopper opening 16. The lower wings 30 of the fixing parts 26 of the connecting members 25 extend in the hopper opening 16 while the rods 36 and the sleeves 37 of the reservation parts 35 of the connecting members 25 are arranged outside the hopper opening 16, at a distance and facing a part of the outer surfaces 18b of the walls of formwork 18, and in particular of corners where the transverse edges 19 of the formwork walls 18 meet.

The distance dl between the rod 36 and the fixing part 26, the length L1 and the diameter Dl of the rod 36 as well as the length 1 and the outside diameter of the sleeve 37 are appropriately chosen to form, in the slab 2 near the hopper 3, a reservation hole 10 adapted to receive and ensure reliable maintenance of a post 12 of a railing 11 intended to secure the hopper 3 as will appear from the following description. By way of nonlimiting illustrative example, the distance dl between the rod 36 and the fixing part 26 is between 85 mm and 105 mm, for example equal to 94 mm, the length L1 of the rod 36 is between 180 mm and 220 mm, for example equal to 199 mm, the diameter Dl of the rod 36 is between 20 mm and 30 mm, for example equal to 25 mm, the length 1 of the sleeve 37 is between 120 mm and 140 mm, by example equal to 130 mm, and the outside diameter De of the sleeve 37 is between 20 mm and 30 mm, for example equal to 26 mm.

The invention has been described in relation to a formwork 15 having a rectangular outline obtained by an assembly of four straight formwork walls 18 by means of four connecting members 25. The invention is not limited to such an embodiment . In other embodiments, the formwork 15 could have an outline of any other shape adapted to the shape of the hopper 3 desired. In addition, the formwork 15 can be obtained from a formwork system 17 comprising two or more of two formwork walls 18 suitably shaped and connected together by two or more of two connecting members 25 also shaped any suitable way. In particular, the angle between the plates 27 of the fixing part 26 of the connecting member 25 could be different from 90 °. The fixing part 26 could be fixed to the lower side 20 or upper side edges 21 of the formwork walls 18. Furthermore, each connecting member 25 could connect more than two formwork walls 18.

In FIGS. 1 and 5 to 7, the formwork system 17 further comprises a reinforcement device 45 extending in the hopper opening 16 transversely with respect to the formwork axis C to support the pushing forces of the material of which slab 2 is formed during the formation of slab 2.

In FIG. 1, the reinforcing device 45 comprises a reinforcing wall 48 formed by a straight board having a length between two opposite transverse edges 49. The length of the reinforcing wall 48 is substantially the same as that of the short formwork walls 18 of the formwork system 17.

In FIGS. 5 to 7, the reinforcing device 45 also comprises two reinforcing members 55 configured to each support one of the transverse edges 49 of the reinforcing wall 48 and to be mounted respectively on two shuttering walls 18.

Each reinforcing member 55, made of metal or any other suitable material, comprises a fixing part 56 configured to be fixed to the formwork wall 18. In particular, the fixing part 56 comprises a plate 57 extending along an axis of extension E of the opposite lower 58 and upper 59 ends, and having opposite inner 56a and outer 56b surfaces. As for the connecting member 25, the lower end 58 of the fixing part 56 of the reinforcing member 55 is provided with a lower wing 60 which extends perpendicular to the extension axis E on the side of the internal surface 56a. The upper end 59 of the fixing part 56 of the reinforcing member 55 is, for its part, provided with an upper wing 61 which extends perpendicular to the extension axis E on the side of the external surface. 56b, in a direction opposite to the lower wing 60. To retain one of the transverse edges 49 of the reinforcement wall 48, the fixing part 56 of the reinforcement member 55 further comprises two stops 62 projecting relative to to the internal surface 56a of the plate 57 so as to delimit between them a space adapted to receive the transverse edge 49. In particular, in the embodiment shown, the stops 62 include two tongues extending along the axis of extension E, parallel to one another and secured to the internal surface 56a of the plate 57 and to an upper surface of the lower wing 60. In the figures, the fixing part 56 is produced from '' a metal sheet folded to form the plate 57, the lower wing 60 and the upper wing 61, the stops 62 being welded to the internal surface 56a of the plate 57 and the upper surface of the lower wing 60.

Each reinforcing member 55 also includes a reservation part 65 extending along a reservation axis R parallel to the extension axis E, at a distance and facing the external surface 56b of the fixing part 56. As for the connecting member 25, the reservation part 65 comprises a cylindrical rod 66 along the reservation axis R. The rod 66 is arranged at a distance d2 from the fixing part 56 and has a length L2 measured along the axis of reservation R and a diameter D2 measured perpendicularly to the axis of reservation R. The reservation part 65 may also comprise a sleeve similar to the sleeve 37 described above, fitted removably on the rod 66.

The distance d2 between the rod 66 and the fixing part 56, the length L2 and the diameter D2 of the rod 66 are appropriately chosen to form, in the slab 2 near the hopper 3, a suitable reservation hole 10 to receive and ensure reliable maintenance of a post 12 of the railing 11. The distance d2 between the rod 66 and the fixing part 56, the length L2 and the diameter D2 of the rod 66 may be identical respectively to the distance dl between the rod 36 and the fixing part 26 of the connecting member 25, the length LI and the diameter Dl of the rod 36 of the connecting member 25.

For each reinforcing member 55, the external surface 56a of the plate 57 of the fixing part 56 is brought into contact with the internal surface 18a of the wall portion formed in the middle of one of the long formwork walls 18 . The reinforcing members 55 are arranged in such a way that the lower ends 58 and the lower wings 60 of the fixing parts 56 are coplanar with the lower lateral edges 20 of the formwork walls 18. The plate 57 of the fixing part 56 is then fixed by any suitable means, and in particular by screwing, to the wall portion. The lower wings 60 of the fixing parts 56 of the reinforcing members 55 extend into the hopper opening 16 while the rods 66 and, if necessary, the sleeves of the reservation parts 65 of the reinforcing members 55 are arranged in outside the hopper opening, at a distance and facing a median part of the exterior surfaces 18b of the formwork walls 18.

In other embodiments, one or more reinforcing devices 45 arranged in any suitable manner and comprising a formwork wall 48 and two reinforcing members 55 shaped in any suitable manner could be provided.

In connection with FIGS. 8 to 13, a method for producing a slab 2 of a building 1 comprising a hopper 3 with the formwork system 17 is now described.

In Figure 8, a structure 4 adapted to support the slab 2 is mounted. In particular, the structure 4 may comprise beams 5 resting parallel to one another on the walls 70 of the building 1 and optionally on stays 71, and rows of slabs 6 mounted between the beams 5. The beams 5 and the slabs 6 cover a surface corresponding to the surface of slab 2, with the exception of an opening where the hopper 3 must be placed. A closure plate 72 is maintained on a lower surface of the structure 4 opposite to an upper surface on which the slab 2 must be formed to temporarily close the opening. Edges 7 having a height corresponding to a thickness of the slab 2 extend from the periphery of the structure 4. The slabs 6 can be covered with a wire mesh 8.

The formwork system 17, in the assembled state to form the formwork 15 as described above, is put in place on the opening, the lower wings 30, 60 of the connection 25 and reinforcement 55 resting on the plate. obturation 72 and being fixed thereto by any appropriate means and in particular by screwing.

In Figures 9 and 10, the slab 2 is formed on the structure 4 and around the formwork 15 for example by pouring the material of which the slab 2 is made in a fluid state.

In FIG. 11, after the material has dried, the formwork 15 can be removed, the slab 2 then having a hopper 3 and reservation holes 10, delimited by the sleeves 37, at the locations previously occupied by the reservation parts 35, 65 connecting members 25 and reinforcement 55.

In FIGS. 12 and 13, the railing 11 can be placed around the hopper

3. The railing 11 comprises the posts 12 mounted in the reservation holes 10 and crosspieces 13 and a plinth 14 mounted on the posts 12.

Claims (10)

1. Formwork system (17) for making a hopper (3) in a slab (2) of a building (1), the formwork system (17) comprising: - at least two formwork walls (18) each having opposite inner (18a) and outer (18b) surfaces, - at least two connecting members (25) configured to, in an assembled state of the formwork system (17), link the formwork walls (18) to each other so as to form a formwork (15) having a closed contour around a hopper opening (16) along a formwork axis (C), the interior surfaces (18a) of the formwork walls (18) delimiting the hopper opening (16), the formwork system (17) being characterized in that each of the connecting members (25) comprises: - a fixing part (26) configured to be fixed on wall portions of at least two formwork walls (18) in the assembled state of the formwork system (17), - a reservation part (35) extending along a reservation axis (R) parallel to the formwork axis (C), at a distance from the fixing part (26), the reservation part (35) being arranged remotely and facing a part of the external surfaces (18b) of the formwork walls (18) in the assembled state of the formwork system (17) so as to be able to form a reservation hole (10) in the slab (2 ) away from the hopper (3). 2. Formwork system (17) according to claim 1, wherein the reservation part (35) comprises a rod (36) cylindrical along the reservation axis (R). 3. Formwork system (17) according to claim 2, wherein the reservation part (35) further comprises a sleeve (37) cylindrical along the reservation axis (R) removably fitted on the rod (36) . 4. Formwork system (17) according to any one of claims 1 to 3, in which each formwork wall (18) has a length between two opposite transverse edges (19), the wall portions of each formwork wall ( 18) being provided respectively in the vicinity of the transverse edges (19), and in which the fixing part (26) of each connecting member (25) forms an angle iron comprising two plates (27) forming an angle around an axis of fixing (F), in particular a right angle, each of the plates (27) of the angle iron being fixed to the wall portion of one of the formwork walls (18) in the assembled state of the formwork system (17) . 5. Formwork system (17) according to claim 4, wherein the fixing part (26) of each connecting member (25) has a height measured along the fixing axis (F) and internal surfaces (26a) and external (26b) opposite, the reservation part (35) being arranged opposite the external surface (26b) of the fixing part (26), the external surface (26b) of the fixing part (26) being contact with the wall portions. 6. Formwork system (17) according to claim 5, wherein each formwork wall (18) has a height between opposite lateral edges lower (20) and upper (21), the fixing part (26) of each member connecting (25) extending along the fixing axis (F) between opposite lower (28) and upper (29) ends, the lower end (28) of the fixing part (26) being provided with a lower wing (30) extending perpendicular to the fixing axis (F) in a direction opposite to the reservation part (35), the lower ends (28) of the fixing parts (26) being coplanar with the edges lower sides (20) of the formwork walls (18) and the lower wings (30) of the fixing parts (26) extending into the hopper opening (16) in the assembled state of the formwork system. (17) 7. Formwork system (17) according to any one of claims 1 to 6, further comprising at least one reinforcement device (45) comprising: a reinforcing wall (48) having a length between two opposite transverse edges (49), and - two reinforcing members (55) configured to each support one of the transverse edges (49) of the reinforcing wall (48) and to be mounted respectively on two formwork walls (18) so that, in the assembled state of the formwork system (17), the reinforcement wall (48) extends in the hopper opening (16) transversely with respect to the formwork axis (C), in which each of the reinforcement members ( 55) includes: - a fixing part (56) configured to be fixed on the formwork wall (18) in the assembled state of the formwork system (17), - a reservation part (65) extending along a reservation axis (R) parallel to the formwork axis (C), at a distance from the fixing part (56), the reservation part (65) being arranged remote and facing a part of the external surface (18b) of the formwork wall (18) in the assembled state of the formwork system (17) so as to be able to form a reservation hole (10) in the slab (2) away from the hopper (3). 8. Connecting member (25) specially adapted for a formwork system (17) according to any one of claims 1 to 7, the connecting member being configured for, in an assembled state of the formwork system (17), connecting shuttering walls (18) to each other so as to form a shuttering (15) having a closed contour around a hopper opening (16) along a shuttering axis (C), interior surfaces (18a) formwork walls (18) delimiting the hopper opening (16), the connecting member (25) comprising: - a fixing part (26) configured to be fixed on wall portions of at least two formwork walls (18) in the assembled state of the formwork system (17), - a reservation part (35) extending along a reservation axis (R) parallel to the formwork axis (C), at a distance from the fixing part (26), the reservation part (35) being arranged remotely and facing a part of the external surfaces (18b) of the formwork walls (18) in the assembled state of the formwork system (17) so as to be able to form a reservation hole (10) in the slab (2 ) away from the hopper (3). 9. A method of producing a slab (2) of a building (1) comprising a hopper (3), the production method using a formwork system (17) according to any one of claims 1 to 7 and planning to: - mount a structure (4) adapted to support the slab (2), - Form a formwork (15) having a closed contour around a hopper opening (16) along a formwork axis (C) by putting the formwork system (17) in the assembled state, connecting members (25 ) connecting the formwork walls (18) to each other, a fixing part (26) of each connecting member (25) being fixed on wall portions of at least two formwork walls (18), a part of reservation (35) of each connecting member (25) being arranged at a distance and facing a part of external surfaces (18b) of the formwork walls (18), of the internal surfaces (18a) of formwork walls (18 ) delimiting a hopper opening (3) along the formwork axis (C), - form the slab (2) on the structure (4) and around the formwork (15), -removing the formwork (15), the slab (2) having a hopper and reservation holes (10) in locations previously occupied by the reservation parts (25) of the connecting members (25). 10. The production method according to claim 9, further providing for mounting a bodyguard (11) around the hopper (3), the bodyguard (11) comprising posts (12) mounted in the reservation holes ( 10) and crosspieces (13) mounted on the posts (12). 1/5