FR3028281A1 - SUPPORTING DEVICE AND FORMWORKING METHOD USING SUCH A DEVICE - Google Patents

Abstract

A retaining device (1), in particular for the horizontal formwork support, comprises a retaining strut (2) comprising a base (21), a support head (22) of a horizontal formwork and at least one element ( 23, 24) slidably mounted in said base (21) and connecting said base (21) to said support head (22), the retaining device (1) also comprises hydraulic drive means (3) adapted to drive said element (23, 24) between a vertical low position of installation of the formwork and a predetermined vertical high position of formwork and servo means (4) of said drive means (3) able to maintain said support head (22). ) at said predetermined vertical high position of formwork during a formwork operation.

Description

The present invention relates to the field of shoring and, more particularly, to a support device for moving a horizontal formwork platform so as to provide a support structure. to form a slab, a floor or a balcony. In known manner, a horizontal formwork platform comprises a support structure on which is mounted a formwork skin intended to receive the concrete. The support structure is generally constituted of primary beams based on retaining devices and secondary beams resting on said primary beams. Plywood forming the formwork skin are positioned on the secondary beams.

In practice, the support devices comprise telescopic props to move from a low installation position, in which the formwork platform is set up before pouring the concrete, to a high formwork position, in which the concrete is sank. In the high formwork position, significant forces pass through the retaining devices to support the weight of the concrete. By way of example, patent application FR2823521 discloses a support device comprising a telescopic stay powered by a worm powered by an electric motor to move the formwork platform from the low position of installation to the high formwork position. To lock the forestay in the high formwork position, an operator must install a pin in the forestay to lock it in position. To do this, the operator must move under the formwork platform, that is to say under a load, which may present a risk for operators.

In order to eliminate this disadvantage, an obvious solution would be to control the pinning by means of a PLC in order to avoid the movement of an operator under the load. However, such a solution is complex and expensive to set up.

The object of the invention is to provide an improved support device whose movement between the low installation position and the high formwork position is easy and carried out safely for operators. Another objective is to provide a support device whose handling is simple to limit the difficulty of operators. GENERAL PRESENTATION OF THE INVENTION In order to eliminate at least some of these drawbacks, the invention relates to a support device, in particular for the horizontal formwork support, comprising a support strut comprising a base, a support head of a horizontal formwork and at least one member slidably mounted in said base and connecting said base to said support head, the retaining device comprising hydraulic drive means able to drive said element between a low vertical position of installation of the formwork and a predetermined vertical high position of formwork and servo means of said drive means adapted to maintain said support head at said predetermined vertical high position of formwork during a formwork operation.

With the support device according to the invention, the establishment of a horizontal form is easy thanks to the low position of the device for work at human height. In addition, the vertical displacement of the horizontal formwork is fast and easy thanks to the hydraulic drive means. The device according to the invention also makes it possible to avoid any movement of the operators under the formwork platform. During a formwork operation, the concrete exerts a force on the forestay which is directed downwards. Thanks to the servo means, the drive means are activated to compensate for the weight of the concrete and maintain the support head in the up position. The hydraulic drive means also make it possible to dismantle in a practical and fast manner, without requiring the movement of an operator under the load. Preferably, the hydraulic drive means are autonomous. Thus it is not necessary to use a remote hydraulic unit which would be connected to the device according to the invention by supply lines. The support device can thus be moved individually, without constraints, in the manner of a forestay according to the prior art. Preferably, the hydraulic drive means comprise at least one hydraulic fluid reservoir and at least one pump capable of driving the hydraulic fluid of said reservoir into said support prop. Thus, it is sufficient to control the pump to cause a rise or fall of the support head. The servo means are configured to control said pump, preferably electrically.

Preferably, the drive means comprise a hydraulic jack, mounted in said strut, for driving said support head. Preferably, the servocontrol means comprise at least one distance sensor 15 configured to measure the displacement of the support head and deduce a control setpoint from said drive means. Thus, the control setpoint represents the displacement that the drive means must compensate. Preferably, the distance sensor is configured to provide a control setpoint after initialization in the formwork high position. Preferably, the drive means comprising a hydraulic cylinder for driving said support head, the distance sensor is configured to measure the displacement of said cylinder to indirectly deduce the displacement of the support head. Preferably, the servo means are autonomous. Thus, it is not necessary to electrically connect the device according to the invention to a power supply. Preferably, the drive means comprise a solenoid valve to allow the forestay to be lowered in a controlled manner, without the need to move an operator under the load. In the prior art, an operator must move under the load to act on the threaded handle of the mechanical props in order to release the efforts related to the drying of the concrete.

Preferably, the support device comprises a chassis module and a removable control module of said chassis module, said modules being connected electrically and fluidically. Maintenance of the retaining device is facilitated because of its modular structure. Preferably, the device comprises stabilization means on the ground of the device in the upright position of use and means of movement on the ground of the device in an inclined transport position. Thus, the device is stable during use while being able to be moved easily. Preferably, the stabilizing means is configured to be active when the device is upright in use and inactive when the device is in an inclined transport position. Thus, it is sufficient to maintain the device in the vertical position so that the latter is stable. Preferably, the displacement means are configured to be inactive when the device is in a vertical position of use and active when the device is in an inclined transport position. Thus, it is sufficient to tilt the device to allow easy movement. Preferably, the displacement means comprise at least one auxiliary wheel adapted to stabilize the device in an inclined position. Thus, it is easy to change direction during the movement of the support device and with less effort. The auxiliary wheel is, preferably, mounted crazy. Preferably, the support device does not include broaching means. Thus, no operator has to go under the formwork platform to block formwork position. Preferably, the retaining device comprises a remote control adapted to control said drive means, preferably in a wireless manner. Preferably, the remote control communicates radially with the drive means on a so-called "unbuffable" radio frequency in order to avoid any risk of malfunction. The invention also relates to a formwork method by means of at least one retaining device comprising a strut comprising a base, a support head and at least one member slidably mounted in said base and connecting said base to said support head method, comprising: - a step of installing a horizontal formwork on said support head at a low vertical installation position of the formwork, - a step of driving the support head to a predetermined high vertical position of formwork, - a step of pouring concrete on said horizontal formwork, and - a step of controlling the drive of the support head to said upright position so as to compensate for any displacement of the support head 15 after casting concrete. Thanks to the formwork method according to the invention, maintaining the height of the formwork platform is simple and inexpensive to set up and does not require the movement of an operator under said platform. Preferably, the method comprises a step of stabilizing the device in a vertical position prior to the step of installing said horizontal formwork. Preferably, the method comprises: - a step of receiving a confirmation message of the high vertical position of the support head prior to the pouring stage of concrete on said horizontal formwork; a step of determining a difference in height of the support head with respect to said high vertical position after the concrete pouring step on said horizontal formwork, and a step of driving the support head into position; function of said height difference so as to compensate for any displacement of the support head following the pouring of the concrete.

In other words, the invention relates to a formwork method using at least one retaining device comprising a strut comprising a base, a support head and at least one member slidably mounted in said base and connecting said base to said head of support, method comprising: - a step of installing a horizontal formwork on said support head at a low vertical position of installation of the formwork, - a step of driving the support head to a predetermined high vertical position of shuttering, - a step of receiving a confirmation message from said vertical high position of the support head, - a step of pouring concrete on said horizontal formwork, - a step of determining a height difference of the head of support relative to said high vertical position, then - a step of driving the support head according to said height difference so as to compensate for any displacements the support head after the pouring of the concrete. Thus, the determination of the displacement of the support head with respect to the vertical high position controls the driving of the support head.

Preferably, the method, using at least two support devices, comprises: a step of installing a horizontal formwork on said support heads at a low vertical position for installing the formwork; synchronized driving step of said support heads to a predetermined vertical high position of formwork, - a step of pouring concrete on said horizontal formwork, then - a step of individual servocontrol of the drive of each support head in vertical position predetermined high formwork so as to compensate for any displacement of the support head following the pouring of the concrete. Thus, the servocontrol of each support device is independent of the servocontrol of the other support devices and only depends on the displacement of the support head of each support device. Such an implementation facilitates the management of a plurality of support devices. PRESENTATION OF THE FIGURES 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: FIG. 1 represents a schematic view of a support device according to the invention in a vertical high position, - Figure 2 shows a schematic diagram of a training step, - Figure 3 shows a schematic side view of the support device in vertical low position when supporting a platform FIG. 4 shows a schematic side view of the support device in a high vertical position during the support of a formwork platform, and FIG. 5 represents a schematic side view of the support device in an inclined position.

It should be noted that the figures disclose the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate.

DESCRIPTION OF AN EMBODIMENT AND IMPLEMENTATION With reference to FIGS. 1 to 5, there is schematically represented an embodiment of a retaining device 1 according to the invention. Such a retaining device 1 is used to maintain a horizontal formwork in height, for example, to form a balcony. With reference to FIG. 1, the retaining device 1 comprises a retaining strut 2, hydraulic drive means 3 for allowing the deployment of said retaining strut 2 and servo means 4 of said drive means 3 adapted to maintain the support prop 2 deployed during a formwork operation. In this embodiment, the retaining device 1 also comprises stabilization means 6, displacement means 7 and gripping means 8 of the retaining device 1.

As will be presented later, such a support device 1 makes it possible to lift a formwork platform easily by avoiding an operator to move under said formwork platform.

Each part of the retaining device 1 will now be presented in detail before addressing an implementation of a formwork operation. With reference to FIG. 1, the support strut 2 comprises a base 21, a support head 22 of a horizontal formwork and a first element 23 and a second element 24 slidably mounted in said base 21 and connecting said base 21 to said support head 22. In this example, the first member 23 is slidably mounted in said base 21 while the second member 24 is slidably mounted in said first member 23. In this embodiment, the support stay 2 comprises two elements 23, 24 slidably mounted in said base 21 but it goes without saying that it could include a different number of elements. The base 21, the first element 23 and the second element 24 cooperate together telescopically to reduce the size of the retaining strut 2 during storage. In this example, the length of the retaining strut 2 can vary between 1.1 m and 3.6 m to allow, on the one hand, the installation of a formwork platform in a vertical low PVB position (Figure 3 ) and, on the other hand, the positioning of the formwork platform at a high vertical position PVH (Figure 4).

The base 21, the first element 23 and the second element 24 are cylindrical and have a circular section, but it goes without saying that other section shapes (rectangular, square, etc.) could also be suitable. Preferably, the base 21, the first element 23 and the second element 24 are metallic.

The support head 22 is adapted to support a primary beam as will be presented later. For this purpose, the support head 22 has a fork shape.

To modify the length of the stay 2, the support device 1 comprises hydraulic drive means 3. In this example and with reference to FIG. 2, the hydraulic drive means 3 comprise a hydraulic jack 31 mounted in the base 21 of the retaining strut 2 in order to deploy it, a hydraulic reservoir 32 and a pump 33 for supplying the cylinder 31 from a hydraulic fluid F stored in the reservoir 32. In this example, the hydraulic fluid F is oil. Preferably, the drive means 3 further comprises a solenoid valve 34 mounted between the jack 31 and the pump 33 to control the descent of the retaining shim 2. The jack 31 comprises a cylinder mounted in the base 21 and a piston connected to the first element 23, in order to vertically move the first element 23 in the base 21 and thus drive the support head 22 between a low vertical position PVB, said installation position of the formwork, and a high vertical position PVH , called formwork position. A hydraulic system is configured to vertically move the second member 24 in the first member 23 during the vertical movement of the first member 23 in the base 21. Such telescopic stay 2 comprising a hydraulic cylinder 31 is known to those skilled in the art.

The hydraulic reservoir 32 supplying hydraulic fluid F the pump 33 provides a hydraulic autonomy of the support device 1. The support device 1 therefore comprises a self-contained hydraulic system requiring no external or remote power supply.

The solenoid valve 34 controls the descent of the formwork platform. The hydraulic fluid has a viscosity of less than 32 cSt (centistokes) for a temperature between -20 and + 70 ° C. To do this, the solenoid valve 34 is placed between the cylinder 31 and the pump 33 to regulate the hydraulic flow when the hydraulic fluid F exits the cylinder 31, that is to say, when the strut 2 is lowered. Such solenoid valve 34 is simple and inexpensive to set up, and allows the use of a hydraulic cylinder 31 single-effect, less expensive. Such a solenoid valve 34 allows the descent of the strut 2, in particular during stripping operations.

Still with reference to FIG. 2, the servo-control means 4 comprise an electronic system 41 configured to control the drive means 3, an electric battery 42 for electrically powering the electronic system 41, wireless communication means 43 capable of communicate with a remote control 5 and a distance sensor 44 able to detect the rise / fall of the forestay 2. The electronic system 41 is configured to control the pump 33 of the drive means 3 in order to adjust the height of the forestay. 2. Similarly, the electronic system 41 is configured to control the solenoid valve 34 to control the descent of the retaining shim 2. For this, the electronic system 41 is electrically connected, on the one hand, to the pump 33 and, on the other hand, to the solenoid valve 34. The electric battery 42 supplies the electrical power supply E to the various elements of the retaining device 1 (pump 33, electrical system onique 41, wireless communication means 43, etc.).

The control means 4 can be remotely controlled by an operator. This operator has a remote control 5 to control the movements of a view of several support devices 1 according to the invention simultaneously to move a formwork platform. The remote control communicates wirelessly with the wireless communication means 43 on a so-called "unbearable" radio frequency in order to avoid any risk of malfunction. The commands R sent by the remote control 5 are received by the wireless communication means 43 and then processed by the electronic system 41 to determine the control of the pump 33 or the solenoid valve 34.

In this example, the control means 4 further comprises a distance sensor 44 adapted to indirectly determine the height of the support head 22 by measuring the output distance of the cylinder 31, that is to say the Piston outlet of the cylinder of the cylinder 31. During the deployment of the strut 2, the distance sensor 44 makes it possible to control the automatic rise of the strut 2 up to a height predefined by the operator. The distance sensor 44 also makes it possible to control the maintenance of the formwork platform at a predefined height during the pouring of the concrete as well as during the formwork. In practice, the maintenance height is achieved by recording the output distance of the cylinder 31 in the high formwork position, any change in this distance during the pouring of the concrete or the formwork communicating to the electronic system 41 to control the pump 33 or the solenoid valve 34 to bring the formwork platform to said predefined height.

When moving a formwork platform comprising a plurality of support devices 2, the distance sensor 44 can be used to ensure the horizontality of said platform, that is to say by controlling the rise / fall from all the struts 2 at the same speed. This coordinated management is implemented by means of the remote control. Still with reference to FIG. 1, the stabilizing means 6 of the support device 1 comprise a stationary front stabilization foot 61 and two movable lateral stabilizing feet 62 capable of passing from a position of use, called the unfolded position (FIGS. 1, 3 and 4), at a storage position, said folded position (Figure 5). In this example, the lateral feet 62 are hinged relative to the strut 2. Preferably, the stabilizing feet 61, 62 have their support on the ground spaced at a distance of less than 0.9 m from the 2 in order to limit the size of the support device 1. In practice, during storage and movement of the device 1, the lateral legs 62 are folded forward, ie on both sides of the front foot 61 as shown in Figure 5. The lateral feet 62 can be unfolded and locked in the unfolded position corresponding to an angular offset of the order of 120 ° between each foot, as shown in Figure 1. The feet of stabilization 61, 62 are distributed at the periphery of the stay 2.

The folded position makes it easy to move and set up the support device 1. During a formwork, the support device 1 is stabilized in a vertical position by placing the two lateral legs 62 in the unfolded position.

In this example, the stabilizing means 6 comprise three stabilizing feet 61, 62 but it goes without saying that they could include two or more of three. Similarly, the angular distribution of the feet 61, 62 could be different. With reference to FIG. 1, the displacement means 7 comprise two main wheels 71 and an auxiliary wheel 72. The main wheels 71, the diameter of which is between 20 cm and 40 cm, preferably of the order of 30 cm. , make it easy to move the support device 1 to the work site. Their large diameter allows the device 1 to be moved even on irregular surfaces such as those that may be present on a construction site. In addition, the main wheels 71 are spaced, preferably of the order of 50 cm, to ensure the stability of the device 1 during its movement. Finally, the main wheels 10 are preferably coaxial and independent of each other in order to facilitate the movement of the support device 1.

The auxiliary wheel 72, non-coaxial with the two main wheels 71, ensures a stable position of the support device 1 when it is in the inclined position PI displacement. In other words, the center of gravity of the device 1 in the inclined position PI of displacement is between the main wheels 71 and the auxiliary wheel 72.

The operator does not need to support the weight of such a device 1 since this weight is entirely distributed between the main wheels 71 and the auxiliary wheel 72. In addition, the auxiliary wheel 72 is steerable, in an inclined position PI around a vertical axis to allow the operator to easily turn the support device 1 during a movement.

In this example, the displacement means 7 comprise three wheels 71, 72 but it goes without saying that they could comprise two or more than three.

With reference to FIG. 1, the gripping means 8 of the retaining device 1 are in the form of a U-shaped handle 80 whose branches extend vertically downwards in order to allow an operator to grasp it in a manner convenient. In addition, the positioning of the handle 80 on the top makes it possible to pass the support device 1 easily from the vertical position to the inclined position. In order to facilitate the maintenance of the support device 1, said device 1 is modular. In other words, the elements of the device 1 are divided into different simple modules to be assembled together. The device 1 according to the invention thus comprises a forestay module 1A, a control module 1B and a chassis module 1C. The retaining strut 2, the cylinder 31 and the distance sensor 44 form the strut module 1A. Such a strut module 1A comprises a hydraulic interface for hydraulically connecting the cylinder 31 to the other hydraulic elements of the drive means 3. The strut module 1A also comprises an electrical interface to enable the distance sensor 44 to transmitting information to the electronic system 41. The control module 1B comprises the reservoir 32, the pump 33, the electronic system 41, the battery 42 and the wireless control means 43. The solenoid valve 34 belongs either to the module Ia was at the control module 1B. Such a control module 1B is easy to remove from the support device 1 during a maintenance operation for example. As illustrated in FIG. 1, the control module 1B comprises a protective cover 11 in order to protect the elements of the control module 1B during work or transport. The cover 11 thus provides protection against shocks, water, dust, etc., while allowing easy and fast access during a maintenance operation of the control module. The stabilizing means 6, the moving means 7 and the gripping means 8 form the chassis module 1C on which the strut module 1A and the control module 1B are fixed. The fasteners are such that it is easy to fix or remove the forestay module 1A and / or the control module 1B in particular for maintenance. Such a modular support device 1 is easy and inexpensive to maintain. In addition, it is easy to modify one of the elements (strut module 1A, control module 1B, chassis module 1C) in order to develop the support device 1 without having to change the device 1 complete, which reduces the costs of such a change. Advantageously, the handle 80 extends around the periphery of the control module 1B to protect it from shocks. An example of implementation will now be presented to perform a formwork operation of a horizontal slab. In the storage position, the props 2 are retracted and the stabilizing feet 61,62 to reduce their size. In practice, an operator moves a plurality of props 1 on the ground to where a slab is to be boxed at a height above the ground. To move each support device 1, the operator inclines the device 1 by means of the handle 80, until the device 1 rests on the displacement wheels 71, 72, which makes it possible to distribute the weight of the device 1 between the main wheels 71 and the auxiliary wheel 72. The center of gravity of the device 1 is between the three wheels 71, 72 to ensure the stability of the device 1 during its movement. Advantageously, the auxiliary wheel 72, which is mounted "crazy", that is to say movable about a vertical axis, allows the operator to easily change the direction of movement of the device 1. In the course of In a next step, the operator uses the handle 80 to pass the retaining device 1 from the inclined position P1 to the vertical low position PVB at the location where the horizontal slab is to be formed. Once in place, the device 1 is stabilized in position by unfolding the stabilizing feet 61, 62. In the stabilized position, the center of gravity of the device 1 is between the support points on the ground stabilizing feet 61, 62.

The formwork is then put in place on the support heads 22 of the plurality of support devices 1. To do this, the operator places a primary beam A on the support head 22, as shown in FIG. , each primary beam A is supported by several support devices 1 aligned in the direction in which the primary beam A extends. The establishment of the primary beams A does not expose the operators to a risk of falling or to efforts important physical since each support head 22 extends to a height of about 1.1 m, when the support device 1 is in the vertical low PVB position. In other words, the installation is carried out at the height of man. In a very easy and convenient way, the secondary beams and plywood are placed on the primary beams A to form the formwork platform.

In a next step, the operator enters the remote control 5 adapted to wirelessly control the supporting devices 1 to lift the formwork platform. When activation of the remote control 5, the wireless communication means 43 of each support device 1 receive R commands which are processed by the electronic system 41 quickly. The latter then activates the hydraulic pump 33 so as to cause the displacement of the various elements 23, 24 mounted telescopically in the base 21. In short, the first element 23 slides vertically upwards in the base 21, which moves the formwork platform up to the formwork height. In this example, the maximum height of formwork is 4 m. The use of a remote control 5 is advantageous and avoids an operator to be located under the formwork platform during the deployment of struts 2. Preferably, the remote control 5 implements deployment management algorithms of each strut. support 2 in order to coordinate a simultaneous deployment of said props 2. In practice, the distance sensors 44 of each support device 1 allow to adapt the deployment speed of each strut 2 to allow a synchronized movement. Preferably, the remote control 5 makes it possible to easily adjust the formwork height and, preferably, the height of each retaining strut 2 individually in order to achieve a precise adjustment of the horizontal position of the formwork platform. The vertical high position PVH of each support head 22 can be set manually by the operator with the remote control 5, the support devices 1 being controlled individually or synchronized. According to a preferred aspect, the remote control 5 is configured to define a high vertical position PVH and send it to the various support devices 1 so that they deploy to the desired vertical high position PVH. In other words, the height adjustment of the formwork platform is automatic. Optionally, ordinary struts may be placed under the formwork platform prior to pouring the concrete.

In a next step, the operator records the formwork height of the support head 22 of each support device 1. To do this, once the formwork platform at the desired height, the operator confirms since the remote control 5 that the formwork height is reached by the support head 22 of each support device 2. Each support device 1 then receives a confirmation and records the height of the support head 22. Thus, the control means 4 of each support device 1 record the output distance of the cylinder 31 when the strut 2 is deployed at the formwork height. During a next step, the operator pours concrete on the formwork platform supported by the devices 1 to form a slab, as shown in Figure 4. The weight of the concrete is applied to the support devices 1 and opposes the hydraulic pressure of the cylinders 31. The platform is maintained in the high vertical position PVH thanks to the control means 4 which compensate the weight P of the concrete by activating the hydraulic drive means 3, preventing any displacement longed for. During pouring, with reference to FIG. 4, under the effect of the weight P of the concrete poured on the casting platform, the primary beam A moves downwards. The beam A 'then has a difference in height AH with respect to said confirmed position. During the pouring of the concrete, the distance sensor 44 determines said height difference AH and communicates it to the electronic system 41 which then activates the pump 33 in order to compensate for the difference in height AH. To do this, the pump 33 is activated until the sensor 44 determines a distance gap AH zero. In other words, the control means 4 control the activation of the pump 33. The servocontrol is individual from one support device 1 to the other, depending only on the height difference AH of the support head 22, which is simple to implement. After drying of the concrete, the operator declines the slab by lowering the props 2 by means of the remote control 5. To do this, the solenoid valve 34 of each device 1 is activated so as to let the hydraulic fluid F contained in the cylinder 31 into its reservoir 32. The control of the output flow of the hydraulic fluid F to control the folding speed of the strut 2. The solenoid valve 34 is also controllable remotely from the remote control 5.

Advantageously, it is thus not necessary that an operator is placed under the formwork platform to perform this step. Similar to the deployment of the forestay 2, the distance sensor 44 of each support device 1 makes it possible to compensate for the differences in efficiency of the different devices 1 in order to maintain the horizontal formwork platform during the stripping.

During concrete drying, disturbances (hydraulic fluid leaks, temperature changes, hydraulic fluid settling, etc.) can cause the formwork platform to move. In the same way as during the pouring of the concrete, the difference in height AH is compensated by the servo-control means 4. The servo-control means 4 activate the pump 33 if the platform moves downwards or the solenoid valve 34 if the platform moves upwards. Activation of the pump 33 or the solenoid valve 34 is done completely automatically, without operator manipulation, so as to stabilize the formwork platform at the height predefined by the operator and recorded after the deployment of the props. 2. The battery 42 and the tank 32 ensures autonomy of each support device 1 in order to stabilize the formwork platform at said predefined height without risk vis-à-vis the power cuts on the electrical network or failure a hydraulic power station.

Preferably, the servocontrol cycle (distance measurement, determination of the difference in height, etc.) is less than 0.1 s, preferably less than 0.05 s in order to reactively control the pump 33 or the solenoid valve 34.

Once the props 2 folded, the formwork platform is dismounted, the lateral stabilizing feet 61, 62 are folded, as shown in Figure 5, and the support devices 1 are stored in their storage location. The maintenance of such a retaining device 1 according to the invention is easy thanks to the modular structure. During maintenance, the different modules 1A, 1B, 1C can be easily separated in order to repair, maintain or change them.

With the support device 1 according to the invention, its rise is fast and requires only a hydraulic pump, which reduces its manufacturing cost. Advantageously, the retaining device 1 is adapted to withstand a dynamic load of the order of 500 kg and a static load of 3 tons. Thus, a limited number of devices 1 can lift and support the mass of the formwork platform. With the support device 1 according to the invention, an operator does not have to be placed under the formwork platform to mount it, block it in position or lower it, which offers optimal safety conditions to the operators and reduces the painfulness. Indeed, in formwork position, no additional operation of the operators is necessary. In particular, it is not necessary to block the props 2 in the deployed position, for example by broaching, as was the case in the prior art.