FR3021337A1 - FORMING PORTIC AND FORMWORK EQUIPPED WITH SUCH A PORTIC, METHOD FOR DECREASING, METHOD FOR MANUFACTURING WALL OR BUILDING PORTION, WALL PORTION AND BUILDING. - Google Patents

Abstract

The formwork gantry comprises: - a base body (9), - two branches (10, 11) movable relative to the base body (9) between a formwork configuration and. a release configuration, - a linkage (20) which comprises an actuating portion (21) moved relative to the base body (9) between a low configuration and a high configuration, the linkage (20) being connected to the branches (10, 11), - an elastic assistance system (33) tending to elastically bias the branches (10, 11) towards their release configuration.

Description

The invention relates to the field of formwork gantries and formwork provided with such gantries, stripping methods, wall or building portion manufacturing methods, wall portions and buildings.

More specifically, the invention relates to the field of formwork. In the field of building and public works, large formwork is used to make concrete walls. These forms comprise two formwork elements, or panels, arranged face to face, and between which the concrete is poured.

It is difficult to keep these large structures stably and vertically stable during pouring of concrete. To alleviate this problem, the applicant has proposed in FR 2 538 832 a gantry which connects the two boards. Using such a gantry increases the stability of the assembly because the two banks are indirectly supported on each other and the overall width of the system allows a better stability.

Another difficulty lies in the fact that after concrete pouring, it is necessary to separate the two panels of one another and the wall formed between them two. This spacing must be done smoothly so as not to damage the wall when the form separates from the wall. In the patent FR 2,538,832 mentioned above, it then assembles the assembly formed two banches and the gantry spreader spreader which, lifted by a crane, will lead to a spacing of the two panels one of the other and the wall formed. As a result, then, the branches of the gantry deviate. The two panels can then be taken to another location, for example for the realization of a subsequent wall. However, the two panels are tied together by the portico, and can not be moved away from the wall in the direction of the wall. The set of rafters, the gantry and the rudder must be moved vertically or horizontally along the wall, with the berms remaining close to the wall, carefully to avoid any contact or impact between the boards and the wall that has just been formed (under conditions that may include wind).

The implementation of the spreader bars is not satisfactory, the applicant had the idea to integrate the spacer function directly to the gantry. This invention was the subject of patent FR 2,700,158. This patent, which has had great commercial success, remains in use today, and is at the state of the art, with the exception of the subsequent improvement. with the pivoting attachment of the gantry spreaders to the banches, object of its patent FR 2 808 041.

Although the above patents are entirely satisfactory, there is still a need to try to reduce the arduousness of the site work of the operators. According to a first aspect, the invention relates to a formwork gantry.

The vertical direction is a reference direction in the field of construction, building and public works and, unless otherwise stated or obvious, it will be subsequently described the gantry in a configuration taking into account this reference direction.

The formwork gantry comprises a base body defining a median formwork plane.

The formwork gantry also comprises two branches extending on either side of the median plane. Each branch extends between a first end connected to the base body and a second end adapted to be connected to a formwork element (or formwork).

Each branch is movable relative to the base body between a formwork configuration and a release configuration. In the formwork configuration, the second ends of the two branches are close to the median plane and down.

In the release configuration, the second ends of the two branches are spaced from the median plane and upwards. The formwork gantry includes a crankshaft. The linkage comprises an actuating portion adapted to be moved relative to the base body between a low configuration and a high configuration. The linkage is connected to the branches so that a placement of the actuating portion from its low configuration to its high configuration moves the branches of the formwork configuration to the release configuration.

The formwork gantry comprises an elastic support system tending to elastically bias the branches towards their release configuration. According to one embodiment, the elastic assistance system comprises a spring mounted between the base body and the actuating portion.

According to one embodiment, the actuating portion comprises, in the low configuration, a fixed part and a movable part with respect to the fixed part, in which the displacement of the movable part with respect to the fixed part in the formwork configuration generates an armament of the elastic assistance system.

According to one embodiment, the movable portion of the actuating portion is rotatably mounted about a horizontal axis relative to the fixed portion of the actuating portion. In one embodiment, the movable portion of the actuating portion comprises a coupling system to a crane hook. According to one embodiment, the elastic assistance system comprises at least one pulley fixed on the actuating portion, a cable guided by the pulley, a longitudinal spring whose one end is fixed to the base body, and a second end is fixed at a first end of the cable, the second end of the cable being operable to arm the spring. According to one embodiment, the elastic assistance system comprises a spring blade comprising a first portion fixed to the actuating portion and a second elastic portion bearing on the base body. According to one embodiment, the actuating portion is slidably mounted relative to the base body. According to one embodiment, the linkage further comprises a first return rod and a second return rod, mounted between the actuating portion and a respective branch. According to one embodiment, each branch comprises a deformable parallelogram with respect to parallel horizontal axes, each branch comprising a second end portion, an upper link and a lower link pivotally mounted on the base body on the one hand and on the second end portion on the other hand. According to one embodiment, each return rod is pivotally mounted on the lower link of the respective branch. In one embodiment, the second end of each branch is articulated about an axis perpendicular to the median plane.

According to another aspect, the invention relates to a formwork comprising a first vertical wall, a second vertical wall facing the first wall, and a portal, in which the second end of each arm is connected to a respective wall, the median plane extending between and parallel to the formwork faces of the first and second panels.

According to one embodiment of the formwork, resting on the ground with the branches in formwork configuration, the support of the formwork on the ground prohibited to the elastic assistance system to move the branches to their release configuration. According to one embodiment of the formwork resting on the ground, the elastic assistance system is at rest.

According to one embodiment of the formwork, resting on the ground, the elastic assistance system is armed. According to one embodiment of the formwork, suspended in the air without resting on the ground, the elastic assistance system elastically urges the branches towards their release configuration.

According to one embodiment, the gantry is a first gantry, the formwork further comprising a second gantry, the second end of each branch of the second gantry is connected to a respective wall, and the first and second gantries are spaced one of the other in a longitudinal longitudinal direction of the formwork.

According to another aspect, the invention relates to a stripping method comprising: b) a formwork is provided, c) the actuation portion of the gantry is moved from the low configuration to the high configuration, the elastic assistance system helping to move the branches to their release configuration.

According to one embodiment, before step b), a) the elastic assistance system is armed. According to one embodiment, in step a), to arm the elastic assistance system, there is provided an actuating portion having a fixed portion and a movable portion movable relative to the fixed portion, and moving the moving portion by relative to the fixed part, the fixed part remaining stationary relative to the base body, with the aid of a hoist.

According to another aspect, the invention relates to a method of manufacturing a wall portion comprising a formwork step, a pouring step of the concrete in the formwork, and a stripping process. According to another aspect, the invention relates to a method of manufacturing a building in which the method of manufacturing a wall with the same formwork is repeatedly implemented in various locations. In another aspect, the invention relates to a wall portion manufactured by the wall portion manufacturing method.

According to another aspect, the invention relates to a building manufactured by implementing the building manufacturing method. The figures of the drawings are now briefly described.

Figure 1 is a partial perspective view of a formwork. Figure 2a is a front view of a gantry according to a first embodiment in formwork configuration. Figure 2b is a view similar to Figure 2a in an intermediate configuration. Figure 2c is a view similar to Figure 2a in the release configuration. Figures 3a and 3b are views in similar configurations to those of Figures 2a and 2c, respectively, for a gantry according to a second embodiment. Figure 4 is a partial perspective view of the configuration of Figure 2c. Hereinafter a detailed discussion of several embodiments of the invention with examples and reference to the drawings. We use on the sites of banches 1, 2 between the faces of which is poured a veil of concrete. In a formwork configuration, shown in Figure 1, the two panels 1, 2 are arranged on the ground 4 of the site. Each shuttering form has a formwork face la, 2a. The two formwork faces 1a, 2a are facing each other and define between them a space 5 in which concrete is to be poured in order to solidify and form a wall. The two formwork faces are each substantially flat and parallel to each other. The panels 1, 2 each comprise a formwork structure 6, 7, itself, having the formwork surface 40, but may also have a number of accessories such as reinforcing means (stiffeners, beams, ...), safety devices, personnel circulation devices (such as gangway, guardrail or access ladder), stabilizing devices, leveling and leveling accessories, among others. 45 The walls for the construction of building walls are heavy products that are not easy to maneuver on site, which requires advanced lifting equipment and ground staff. 25 30 The boards are reusable and their handling is important, especially since it is necessary to proceed to plumb and upgrades and removal of the boards after setting concrete.

On the same site, it is therefore repeated in different places, in a series of operations in which we place two boards facing one another to the plumb and level in the place where a wall is to be made, the boards are stabilized. Then, concrete is poured between the formwork faces la, 2a banches to form a wall in this place. Then, remove the banches to place them in another place where a wall is to realize.

The stabilization of the banches can be carried out in various ways. A possible embodiment for the stabilization is the implementation of an upper portal 3 which connects together two banks 1, 2 facing each other. When pouring the concrete, the boards are in close position. To release the concrete veil, the banches are spread. An arrangement is provided for the panels in which, on the one hand, the stabilization of the two vertical panels face to face in formwork configuration and release is provided by a device of the compass type, scissors or gantry and secondly the gripping and the separation of the two branches are assured. To fix the ideas, it is therefore considered that the formwork surface of each formwork extends vertically in a direction Z, and horizontally in a so-called longitudinal direction Y, the direction X corresponding to the direction of the width of the formwork. The notions of "low", "high", "above" and "below" are given by reference to the vertical direction Z, the bottom being close to the ground. The gantry 3 is assembled to the panels 1 and 2 above them. The gantry is more easily described in its open configuration shown in Figure 2c although, in formwork configuration, the gantry is in fact closed (Figure 1 and 2a). The gantry 3 comprises a compass 8 having a head 9 (or base body) and two branches 10 and 11 articulated each on the head 9. The head 9 is located laterally between the two panels 1 and 2, and above them. Thus, the head 9 is located in a median zone, on either side of which extend the two branches 10 and 11, each in the direction of a respective section. A median plane may be defined as a plane parallel to the form surfaces and passing through the head 9. The branches 10 and 11 may be made symmetrical to each other with respect to the median plane, as in the example presented. Alternatively, the median plane is not necessarily exactly in the middle between the formwork surfaces, and the two branches are not symmetrical to each other. The two branches 10 and 11 are articulated on the head 9 about respective axes of rotation parallel to the 40 formwork surfaces, that is to say, in this case, axes of rotation extending in the direction Y. The branch 10 therefore extends from one end connected to the head 9 to another end connected to the block 1. The branch 10 extends in this direction downwards and outwards. The branch 11 therefore extends from one end connected to the head 9 to another end connected to the block 2. The branch 11 extends in this direction downwards and outwards. The branches 10, 11 are themselves formed by deformable parallelogram systems, so as to improve the vertical stability of the branches. The branch 10 comprises an upper rod 12 and a lower rod 13. The upper 12 and lower 13 rods extend substantially parallel to each other. The first ends 12a, 13a of the upper 12 and lower 13 rods are mounted on the head 9. The second ends 12b, 13b of the upper 12 and lower 13 rods are mounted on an end portion 14 of the branch 10. The montages of which it is question are assemblies pivoting about axes parallel to each other and parallel to the axis Y, in each of the ends 12a, 13a, 13b, 12b, so as to maintain a stable orientation of the end portion 14 during the movement. The branch 11 comprises an upper link 17 and a lower link 18. The upper 17 and lower 18 rods extend substantially parallel to each other. The first ends 17a, 18a of the upper 17 and lower 18 rods are mounted on the head 9. The second ends 17b, 18b of the upper 17 and lower 18 rods are mounted on an end portion 19 of the branch 11. The assemblies of which it is question are assemblies pivoting about axes parallel to each other and parallel to the axis Y, in each of the ends 17a, 18a, 18b, 17b, so as to maintain a stable orientation of the end portion 19 during the movement.

A linkage 20 is used to move the branches from their formwork configuration to their release configuration. The linkage 20 comprises an actuating portion 21 and two return rods 22, 23. The return rods 22, 23 are pivotally mounted each on the actuating portion 21, and are arranged on either side of the plane. median. They are for example symmetrical to each other with respect to this plane.

The actuating portion 21 is made in two parts. The actuating portion 21 comprises a fixed part 24 and a movable part 25. It is on the fixed part 24 that the two return links 22, 23 are mounted. They are pivotally mounted with respect to the fixed part, for example around the same pivot axis, itself also parallel to the Y direction. The return rods 22, 23 are therefore connected at a first end 22a, 23a, to the rod 26 and, at a second end 22b, 23b at a respective branch 10, 11. In the case where the branches 10, 11, are made as deformable parallelograms, the connecting rods 22, 23 are connected, respectively, to the lower link 13, 18, of each branch 10 , 11. These connections are pivotal assemblies of axis parallel to the Y axis. The fixed part 24 is slidably arranged with respect to the head 9. For example, the fixed part 24 comprises a rod 26 extending substantially vertically. The rod 26 is guided vertically sliding relative to the head 9 between high and low positions. The movable portion 25 is mounted movably relative to the fixed portion 24. For example, the movable portion 25 is pivotally mounted relative to the fixed portion 24. The pivot axis 27 is an axis parallel to the Y direction. However, a pivoting along another axis, or even a relative movement other than a pivoting, could be possible. The movable portion 25 is a coupling portion to a crane hook (not shown). The moving part comprises in particular a horizontal bar 28 may be taken by a crane hook. The movable part 25 can thus be picked up by a hoist which also automatically and simultaneously causes the spacing of the branches, and therefore the branches.

The end potion 14 is assembled to the banche. For example, the end portion 14 may be rigid and fixed to the banche. Alternatively, as in the example presented, the end portion 14 may comprise two portions articulated with respect to each other along an axis 29 of horizontal pivoting perpendicular to the median plane (that is to say extending in the X direction). Figure 4 illustrates the constitution of the gantry 3, when viewed according to the slice. Thus, the gantry 3 may, as in the example shown, be substantially symmetrical with respect to the XZ plane. In the example shown, the most central elements are the connecting rods 12 and 13. The head 9 comprises two parallel plates 30 and 31 spaced slightly in the direction Y, so that the rotation shafts of the connecting rods 12, 13 with respect to the head 9 extend between these two parallel plates 30, 31. The fixed part 25 comprises, in addition to the rod 26, an opposite rod 26 'both located on either side and outside the head 9. The two rods 26, 26 'are interconnected by the shaft of rotation of the return rods 22, 23. In the direction Y, the connecting rod 22 extends between the rod 26 and the lower rod 13. It is possible to if necessary provide a return rod 22 ', parallel to the return rod 22, extending in the direction Y, between the rod 26' and the lower link 13. The same description applies to the connecting rod 23, with a slight lateral shift of the return rod 23 relative to the return rod 2 2 in the Y direction, since they are mounted on the same axis. In upper portion, the two rods 26, 26 'are connected together by a flange 32. This can carry the rotation shaft 27 relative to which the movable portion is pivotally mounted. The gantry 3 comprises an elastic assistance system 33. The elastic assistance system 33 comprises a spring 34 tending to bias the branches 10, 11 towards their release configuration. As will be better understood on reading the operation below, the spring 34 tends to generate a downward movement of the head 9 relative to the fixed portion 24 of the actuating portion. The elastic assistance system 33 can be armed. For this, the degree of freedom of the actuating portion 21 is used. Indeed, the displacement of the movable portion 25 of the actuating portion 21 with respect to the fixed portion 24 of the actuating portion 21, all elements remaining fixed elsewhere, can be used to arm the elastic assistance system. This is possible, as long as the form is placed on a support (especially on the ground), since the weight of the various components then prohibits relative movement of the other components relative to each other. A first example of arming is a cable armament. A cable 35 is used, a first end 35a of which is connected to the mobile part 25, and a second end 35b is connected to one end 34a of the spring. The other end 34b of the spring is connected to the head 9. If necessary, a deflection pulley 36 is used to guide the cable in the correct orientation. Indeed, the spring 34 is adapted to generate an engine force in the sliding direction of the rod 26 relative to the head 9. It may for example extend substantially along or parallel to this direction. It is thus possible to provide an upper pulley 36 and a lower pulley 37 on the rod 26, spaced vertically from one another, to guide the cable between its two ends. An outer cowl 38, integral with the rod 26, protects and guides the cable potential pollution or unwanted mechanical stress and always possible on a construction site. The implementation of such a system is described below.

To begin with, the docks and the gantries are delivered to the site, and the docks are assembled in pairs at a gantry on the site. It is possible to use a plurality of gantries per pair of gates, the gantries, identical or different but compatible, being spaced apart from one another in the Y direction.

This assembly is done for example in the location of a first wall to manufacture. The panels are placed on the floor with the desired spacing corresponding to the desired width for the wall. The gantries are then in so-called formwork configuration (we can notice that various wall widths are possible to implement with the panels, the gantry is more or less open, but this corresponds in any case to the so-called formwork configuration). In this configuration, the elastic assistance system is substantially at rest.

Then concrete is poured between the banches, and is allowed to solidify. We then proceed to the separation of the banches from one another and from the wall. The starting situation is where the two parallel and vertical banks rest on the ground or a bearing surface in the close closed configuration, because, for example, a concrete wall has been made and the concrete veil is sufficiently hardened so that stripping can be carried out for further use. A crane hook can then be coupled to the movable portion of the actuating portion 21. This coupling can be done by hand by an operator mounted on the bridge (not shown) above the board and manually assembling the hook. from crane to bar 28, or remotely if technology permits. The crane hook will generate a vertical upward movement of the movable portion, which will lead to a rotation of the movable portion 25 relative to the fixed portion 24 about the shaft 27. This movement causes a movement of the cable 35 Since, at this stage, movement of the head 9 downwardly relative to the fixed part 24 is impossible, because the boards are still resting on the ground, this displacement necessarily leads to a tensioning of the spring 34. (Fig 2b). Once the bar 25 has reached its highest point, further movement of the crane hook upward will also cause the fixed portion 24 upward, so that the head 9 will slide downward relative to the fixed part 24 under the effect of gravity. This sliding down of the head 9 automatically causes a movement of the branches 10, 11 to their release configuration via the connecting rods 22, 23. Simultaneously, the elastic assistance system 33 assists this movement, the spring 34 stretched tending to return to its equilibrium position.

There is thus obtained a fast but stable spacing of the branches 10, 11, and therefore the panels 1, 2 of one another and the wall, and a distance from the ground. The pivot around the shaft 29 also allows some flexibility or freedom of maneuvering the crane hook without direct transmission of all torsional forces to the gantry 3. The assembly can then be taken to a new location. In this new location, the separation of the banches is set by operators on the ground pushing on the banks as long as they are suspended, before the system is placed on the ground.

The operations that have just been exposed are carried out at each rotation of the banches. According to a second embodiment, it is not necessary to use a cable arming system. For example, it is possible to use a leaf spring 34 '(FIG 3a, 3b), one end of which is connected to the movable part, and a second end, spring, bears on the head 9 in the formwork configuration. The leaf spring 34 'has a geometry ensuring contact of the spring end portion at least at the beginning of, and for example over the entire range of relative movement of the rod 26 and the head 9. In the example shown, in formwork configuration, as shown in Figure 3a, the spring end of the spring blade 34 'is at a distance from the head 9. The displacement of the movable portion 25 of the actuating portion relative to the fixed part 24 thereof, for example during lifting by the crane hook implies a displacement of the spring blade 34 ', until the spring end thereof comes to rest on the head 9. Continued movement of the movable portion 25 of the actuating portion relative to the fixed portion 24 thereof will store the elastic energy in the spring blade. When lifting the formwork, the elastic force imposed by the spring blade 34 'eventually exceeds the reaction force from the ground, which has the effect of moving the head 9 downwards relative to the fixed part 24, which helps to move the branches, and therefore the branches, upward (contributing all the more to reduce to zero the reaction force from the ground). In the above examples, the connecting rods are devices of constant length, having two ends pivotally mountable.

In the present document, the term "rest on the ground" a configuration in which the soil exerts on the object a reaction corresponding to at least a substantial part, and in particular to all, the weight of the object. Two examples of elastic elements, designated by the term "spring", have been presented here schematically. Other variants of devices that can exert an elastic force, passively, are conceivable within the scope of the invention. In the above examples, gravity is used, and in particular the reaction force on the ground of the weight of the rafters to prevent the tensioned spring from returning to its equilibrium position. However, alternatively, one could provide a mechanism independent of gravity, for example lock type operable directly or indirectly by a user, to implement this function. The use of gravity, however, has the advantage of eliminating such an additional system. The use of a lock-type system allows greater flexibility for triggering the action of the spring.

Claims (25)

REVENDICATIONS1. Formwork gantry in vertical position comprising: a base body (9) defining a median formwork plane, two branches (10, 11) extending on either side of the median plane each between a first end connected to the body of base (9) and a second end adapted to be connected to a formwork element (1, 2), and movable relative to the base body (9) between: a formwork configuration in which the second ends of the two branches (10, 11) are close to the median plane and downwards and. a release configuration, in which the second ends of the two limbs (10, 11) are spaced apart from the median plane and upwards, a linkage (20) comprising an actuating portion (21) adapted to be displaced relative to the body base (9) between a low configuration and a high configuration, the linkage (20) being connected to the branches (10, 11) so that a positioning of the actuating portion (21) from its low configuration in its high configuration moves the branches (10, 11) of the formwork configuration to the release configuration, an elastic assistance system (33) tending to elastically bias the branches (10, 11) towards their release configuration. 2. Formwork gantry according to claim 1 wherein the elastic assistance system (33) comprises a spring (34, 34 ') mounted between the base body (9) and the actuating portion (21). 3. Formwork gantry according to claim 1 or 2, wherein the actuating portion (21) comprises, in the low configuration, a fixed portion (24) and a movable portion (25) relative to the fixed portion (24). ), wherein the displacement of the movable portion (25) relative to the fixed portion (24) in the formwork configuration generates an armament of the elastic assistance system (33). 4. formwork gantry according to claim 3 wherein the movable portion (25) of the actuating portion (21) is rotatably mounted about an axis (27) horizontal relative to the fixed portion (24) of the portion actuator (21). 5. Formwork gantry according to claim 3 or 4 wherein the movable portion (25) of the actuating portion (21) comprises a coupling system (28) to a crane hook. 6. Formwork gantry according to one of claims 1 to 5, wherein the elastic assistance system (33) comprises at least one pulley (36, 37) fixed on the actuating portion (21), a cable ( 35) guided by the pulley (36), a longitudinal spring (34) having a first end (34b) attached to the base body (9), and a second end (34a) attached to a first end of the cable (35b). ), the second end (35a) of the cable (35) being operable to arm the spring (34). 7. formwork gantry according to one of claims 1 to 6, wherein the elastic assistance system (33) comprises a spring blade (34 ') comprising a first portion attached to the actuating portion (21) and a second elastic portion bears on the base body (9). 8. formwork gantry according to one of claims 1 to 7, wherein the actuating portion (21) is slidably mounted relative to the base body (9). 9. Gantry formwork according to one of claims 1 to 8, wherein the linkage (20) further comprises a first connecting rod (22) and a second connecting rod (23), mounted between the portion of actuation (21) and a respective leg (10, 11). 10. Formwork gantry according to one of claims 1 to 9, wherein each branch (10, 11) comprises a parallelogram deformable relative to parallel horizontal axes, each leg (10, 11) comprising a second end portion (14, 19), an upper link (12, 17) and a lower link (13, 18). pivotally mounted both on the base body (9) on the one hand and on the second end portion (14, 19) on the other hand. 11. Formwork gantry according to claim 9 and claim 10, wherein each return rod (22, 23) is pivotally mounted on the lower link (13, 18) of the respective leg (10, 11). 12. Gantry formwork according to one of claims 1 to 11, wherein the second end (14, 19) of each branch is articulated about an axis (29) perpendicular to the median plane. 13. Formwork comprising a first vertical formwork (1), a second vertical formwork (2) facing the first formwork (1), and a frame (3) according to any one of claims 1 to 12, wherein the second end (14, 19) of each branch (10, 11) is connected to a respective wall (1, 2), the median plane extending between and parallel to the formwork faces (1a, 2a) of the first and second panels ( 1, 2). 14. Formwork according to claim 13, resting on the ground with the legs (10, 11) in formwork configuration, in which the support of the formwork on the ground prohibited to the elastic assistance system (33) to move the branches to their release configuration. 15. Formwork according to claim 14, resting on the ground, wherein the elastic assistance system (33) is at rest. 16. Formwork according to claim 14, resting on the ground, wherein the elastic assistance system (33) is armed. 17. Formwork according to claim 13, suspended in the air without resting on the ground, wherein the elastic assistance system (33) resiliently biases the legs (10, 11) towards their release configuration. 35 18. Formwork according to one of claims 13 to 17, wherein the gantry (3) is a first gantry, and further comprising a second gantry according to one of claims 1 to 12, wherein the second end of each branch. the second gantry is connected to a respective wall (1, 2), and wherein the first and second gantries are spaced from each other in a longitudinal longitudinal direction of the formwork. 19. Stripping method comprising: b) providing a formwork according to claim 13 or 18, c) moving the actuating portion (21) of the gantry (3) of the low configuration to the high configuration 45, the elastic system assistance (33) then helping to move the branches (10, 11) to their release configuration. 20. stripping method according to claim 19 wherein, before step b), a) is armed the elastic assistance system (33). 21. Stripping method according to claim 20, wherein, in step a), to arm the elastic assistance system (33), there is provided an actuating portion (21) having a fixed portion (24) and a movable part (25) movable with respect to the fixed part (24), and the moving part (25) is moved relative to the fixed part (24), the fixed part (24) remaining stationary relative to the basic body (24) (9), using a hoist. 22. A method of manufacturing a wall portion comprising a formwork step, a step of pouring concrete into the formwork, and a stripping method according to one of claims 19 to 21. 23. A method of manufacturing a building in which is implemented repeatedly in various locations the method of manufacturing a wall of claim 22 with the same formwork. Wall portion manufactured by the wall portion manufacturing method according to claim 22. 25. Building constructed by implementing the building manufacturing method according to claim 23.