EP0283391A2 - Method for the realisation of concrete structures such as bridge decks, and arrangement for its application - Google Patents

Abstract

The invention relates to a method for making a concrete structure having a lower surface approximately horizontal and separated from the ground. Formwork panels (1) are horizontally disposed and supported by a shoring structure (10,11). These panels are provided, on the one hand, with demountable means for solidly attaching each with its neighbours and, on the other hand, on their lower part, with stiffening elements solidly attached to the panels forming parallel girders. After the concrete has set, the formwork is lowered slightly in order to lay it down onto rolling or sliding means carried by the shoring structure and the entire formwork is moved horizontally until the panels can be demounted without being obstructed by the concrete structure. <IMAGE>

Description

The present invention relates to a method for making a concrete structure having a roughly horizontal lower surface and at least partly spaced from the ground, such as a bridge deck.

The traditional technique, for making relatively small bridges, for example for road crossings, comprises the following stages:

- We first build a shoring structure, consisting of "towers" in metal frame or not, resting on the ground and rising to a height slightly lower than the level of the deck that we want to establish. On this frame, screw systems are provided, with vertical displacement, for leveling and formwork. A series of horizontal beams is placed on these screw systems, and horizontal beams are placed transversely to these beams. On the bastaings, formwork plates are laid, generally made of plywood;

- the concrete is then poured onto the formwork, it is allowed to set, then disassembly is carried out.

To proceed with the dismantling, we start by removing the formwork using screw systems, using the bastaings and beams. We then extract the formwork elements, which are no longer blocked, as well as the bastaings and the beams. In a final phase, the shoring structure is dismantled.

It is understood that all the assembly and disassembly operations of this assembly are long, and require significant work.

It has already been proposed, to reduce these drawbacks, to use formwork panels which are integral with the bastaings, which correspondingly reduces the number of operations. According to another method, it has been proposed to place casters under the towers, and to move the latter, after having lowered the formwork, so as to disassemble without being below the concrete structure. This allows the use of a crane, and considerably speeds up the disassembly process. However, this process requires additional preparation of the ground, since the entire frame must be moved over a distance approximately equal to the width of the bridge.

Another known method, to reduce the duration of the operations, consists in constituting the towers with ladder-shaped elements, which are brought horizontally, straightened on the site and joined together by means of a certain number of horizontal crosspieces. The dismantling of this frame is done fairly quickly: we remove the horizontal crosspieces and rotate the elements in the form of a ladder around a horizontal axis to bring them back to the ground. This solution does not eliminate the operations consisting in removing one after the other the formwork elements, the bastaings if they are not integral with the formwork elements, and the beams.

The present invention aims to provide a process, usable in particular, for making bridges, and which allows faster assembly and especially disassembly considerably simplified and accelerated.

• a) on utilise des panneaux de coffrage solidaires d'une part de moyens pour solidariser entre eux des panneaux adjacents et, d'autre part, d'éléments raidis­seurs rectilignes, ayant la forme de poutres, et paral­lèles entre eux;
• b) on prévoit, entre la charpente d'étaiement et les panneaux de coffrage, des galets ou surface de glisse­ment, susceptibles de coopérer avec lesdits éléments raidisseurs pour déplacer horizontalement l'ensemble formé par les panneaux de coffrage solidarisés entre eux sur une distance limitée;
• c) après la prise du béton, on décoffre, puis on déplace ledit ensemble jusqu'à ce qu'au moins un panneau de coffrage soit au-delà de la structure en béton qui a été coulée et a fait prise;
• d) on désolidarise ce panneau de coffrage des autres et on l'enlève;
• e) on recommence les opérations c) et d) jusqu'à enlèvement de tous les panneaux de coffrage;
• f) on démonte ensuite la charpente d'étaiement.

The invention therefore provides a method for making a concrete structure having an approximately horizontal lower surface and at least partly spaced from the ground, such as a bridge deck, this method comprising the establishment of a shoring frame resting on the ground, laying on this frame formwork panels whose upper surface is roughly horizontal, adjusting the exact position of the formwork elements using lifting means interposed between the frame shoring and the formwork panels, pouring the concrete on these formwork elements and removing the formwork panels and the shoring frame after the setting of the concrete, which has the particularity that:

• a) using formwork panels integral on the one hand with means for joining together adjacent panels and, on the other hand, rectilinear stiffening elements, in the form of beams, and parallel to each other;
• b) there are provided, between the shoring frame and the formwork panels, rollers or sliding surface capable of cooperating with said stiffening elements to horizontally move the assembly formed by the formwork panels secured between them over a limited distance;
• c) after the setting of the concrete, it is stripped, then the said assembly is moved until at least one formwork panel is beyond the concrete structure which has been poured and set;
• d) this formwork panel is separated from the others and removed;
• e) operations c) and d) are repeated until all the shuttering panels have been removed;
• f) then dismantling the shoring frame.

Preferably, the method according to the invention comprises the use of formwork panels provided, on their underside, with a rigid frame equipped with fastening means such as screws and nuts with the similar frame of an adjacent panel, and at least one rectilinear reinforcement, parallel to one of the sides of the frame, and these panels are placed with these parallel reinforcements between them and directed towards the place where the assembly of all the formwork panels will take place.

According to an advantageous method, rollers are used associated with cam-type locking means, arranged to immobilize the formwork panels relative to the frame by lifting them above the rollers, and to release, when the time comes, the formwork panels by resting them on the rollers.

The invention also provides a formwork panel specially usable for implementing the above process, and which comprises:
- a plate made of unfilled cell material, with two layers of coating made of waterproof material;
- reinforcing ribs of unfilled cell material;
a rigid frame on the edges of the plate, with a frame carrying means of connection with the frames of adjacent panels,
the plate, the ribs and the frame being integral with each other.

The material with unfilled cells may consist of a honeycomb type structure, with cells perpendicular to the plane of the plate. However, it is preferred that this material consists of a rigid foam, with firm pores, for example of polyurethane. Such a material is in fact easier to implement, the honeycomb type structure, since there are no special precautions to be taken to prevent the coating material from entering the cells. This advantage generally compensates for a slightly higher weight.

The invention also provides a formwork and bearing device, specially usable in the implementation of the above method, and comprising:

- a yoke formed by a base and two sides;
- a mobile support plate in the screed perpendicular to the base;
- A means capable at will of maintaining the support plate in a first position away from the base and of letting it move to a second position closer to the base;
- at least one roller mounted in the yoke, with an axis parallel to the base, and the top of which is more moved away from it as the outer face of the support plate in its second position; and
- Connection means of the base of the yoke with a support structure, these connection means comprising means for moving the base approximately perpendicular to its plane and a ball joint making it possible to vary within certain limits the orientation of the base with respect to the support structure.

Preferably, in this formwork and rolling device, the means capable of holding and allowing the support plate to move include a cam mounted in the yoke and acting on the internal face of the support plate.

Advantageously, the cam carries a roller which supports the support plate in the first position away from the base and facilitates the start of the movement of the cam from this first position to the second.

• Figure 1 est une vue de dessous, en perspective, d'un panneau de décoffrage pour la mise en oeuvre du procédé selon l'invention.
• Figure 2 est une vue en perspective schématique d'un tablier de pont construit selon le procédé de l'inven­tion, au moment de l'enlèvement des panneaux de décof­frage.
• Figure 3 est une coupe du dispositif à rouleaux pour supporter les panneaux de coffrage.
• Figure 4 est une vue moitié en coupe et moitié en élévation d'une variante du dispositif de la figure 3.

The invention will now be explained in more detail with the aid of a practical example illustrated with the aid of the figures, among which:

• Figure 1 is a bottom view, in perspective, of a formwork panel for implementing the method according to the invention.
• Figure 2 is a schematic perspective view of a bridge deck constructed according to the method of the invention, at the time of removal of the formwork panels.
• Figure 3 is a section of the roller device for supporting the formwork panels.
• FIG. 4 is a view in half in section and half in elevation of a variant of the device in FIG. 3.

The formwork panel shown in FIG. 1 comprises a flat plate 1, of "honeycomb" type structure, with cells oriented perpendicular to its plane, with a layer of waterproof outer coating and a layer of waterproof inner coating, the the material of the outer covering layer being also chosen to have surface properties such that it is not necessary to use formwork oil between the panel and the concrete.

The panel 1 is stiffened, on its four sides, by a rigid frame 2, made of metal, which carries on each of its sides reinforcements 3, having threaded holes 4, in which it is planned to insert screws to secure two elements adjacent to each other.

According to a variant, the holes 4 are eliminated and the assembly of two elements between them is carried out using pliers which bear on the frames of the two elements.

The panel 1 also carries, on its underside, two robust ribs 5, parallel, and of height greater than that of the frame 2.

For the ribs, as for the plate 1, a material with a “honeycomb” type structure was chosen, the cells being oriented perpendicular to the plane of the panel 1, that is to say parallel to the cells of the plate 1.

In an advantageous variant, a rigid polyurethane foam, with firm pores, stabilized, with a density of approximately 90 kg / m³ has been chosen for the plate 1 as for the ribs 5.

The manufacturing of the panels, in this case is as follows:

We place in a mold panels of a resin type "Gelcoat" known for its very poor adhesion to concrete, we deposit on these panels glass fabric impregnated with unpolymerized polyester resin, and on these panels, the foam plate of polyurethane, with its ribs, it is covered with glass fabric impregnated with polyester resin and then with resin panels of the "Gelcoat" type, and the whole is heated until a rigid polymerized unit is obtained.

Advantageously, to facilitate work on site, the resin panels of the Gelcoat type are of different color depending on whether they cover a lower face or an upper face of the panel.

These are the ribs 5 which support the panels and the concrete poured thereon. Their robustness is calculated accordingly. It should be noted that the self-weight of the complete panels is low, of the order of 30 kg / m² or less, the main load therefore consists of the weight of concrete: approximately 250 kg / m² and per decimetre of thickness.

In practice, two types of panels are used, some of which are as described above, and on the others, a series of holes have been created during shaping along the ribs 5, these holes connecting the face. top of the panel to the underside of the rib, in the axial plane thereof. These holes are used for clamping shuttering elements intended in particular for making the edges of the bridge deck.

The operating mode of the process of the invention will now be described with the help of FIG. 2.

After having prepared the ground in a suitable manner, the shoring structure 9 is built, preferably according to the known method which consists in using elements in the form of a ladder 10, which is laid flat on the ground, then that it is straightened vertically and connected together by connecting elements 11.

It is also possible, in accordance with current practice, to constitute the shoring structure with a series of horizontal beams carried on spaced vertical uprights, or on consoles integral with the bridge abutments, to allow passage. The mode of construction of the shoring structure is outside the invention.

The shoring structure carries formwork and rolling devices which will now be described in detail using FIG. 3, before continuing with the description of the process of the invention. These formwork and rolling devices are indeed a very important element for the implementation of the process.

A yoke 12 is formed of a base 13 and two sides 14, parallel and identical, only one of which is shown. In the figure, the yoke is shown in the use position, that is to say with its horizontal base and its vertical sides. Two load bearing 15 parallel are mounted in the yoke, their shafts 16 being in the same horizontal plane, that is to say parallel to the base 13. The flanks each have, in addition, two vertical slots 17, which serve to guide a support plate 18, thanks to pins 19 which penetrate into the slots 17. This support plate, parallel to the base, can thus move vertically between an upper position shown in solid lines, and a lower position shown in dashes. In the lower position, the upper face of the support plate 18 is slightly below the plane defined by the tops of the rollers 15, while it is largely above the same plane when it is in the upper position.

For the movement of the support plate, a cam 20 has been provided, constituted by a cylindrical surface with a generator perpendicular to the plane of the sides 14, and whose guide curve is a spiral. The cam 20 is mounted in the yoke via a shaft 21, of larger diameter than the shafts 15 of the rollers 16, we will see why later. The shaft 21 is integral with a control lever 22, outside the yoke 12. The cam 20 engages the underside of the support plate 18, and the rotation of the lever 22 causes the support plate to pass from the upper position to the lower position, and vice versa.

The spacing between the two plates 14 is greater than the width of the ribs 5, so that these can penetrate the yoke to rest on the rollers 15. The height of the plates 14 above the plane of the tops of the rollers 15 is less than the height of the ribs 5, reduced by the height of the reinforcements 3.

The lower part of the base 13 of the yoke 12 has a recess in the form of a portion of a sphere, into which enters a ball joint 23, mounted on a threaded rod 24, which passes through a "jack nut" 25, provided with handles 26 , and which rests on the end of a tube 27 into which the rod 24 enters. In the case where the shoring structure comprises a frame with vertical tubes, it is one of them which constitutes the tube 27 If this structure is formed of horizontal beams, the tube 27 is a special tube carried by these beams.

The ball 23 being immobilized in rotation either by hand or by friction in the recess of the base 13, the actuation of the handles 26 makes it possible to raise the yoke to the desired height, while the presence of the ball allows the adaptation to slopes or overhangs.

Figure 4 shows a slightly simplified variant of the device of Figure 3. The equivalent parts have the same references in both figures. The cam 20 instead of having a spiral-shaped section, has an elliptical section: It consists of two identical plates, on either side of the plane of the right half of the figure, these two elliptical-shaped plates being mounted, eccentrically on the same shaft 21. At their most distant end from this shaft, the plates 20 carry a roller 30 which goes slightly beyond their end, and which in the position upper supports the support plate 18. Thus, when one acts on the handle 22 to move the cam from its upper position, the latter slides directly against the support plate 18, and its movement is facilitated at first by the presence roller 30, interposed between it and the support plate.

To prevent inadvertent movement of the cam, a fixed stop 31 and a lockable stop 32 are provided which immobilize the handle 22 in the situation corresponding to the upper position of the cam 20.

Another difference from FIG. 3 is that the two bearing bearings 15 have been replaced by a single bearing 33 mounted idly on the shaft 21, between the two elliptical parts which form the cam 20. When the bearing plate is in the lower position, shown in dashes, the bearing 33 passes through a slot 34 of the carrier plate 18 to support the formwork panel.

We will now resume the description of the process.

After having built the shoring structure 9, the tubes 27 are put in place, if necessary, the rods 24 with their nut 25, and the yokes 12, in sufficient quantity to support the formwork. In the direction parallel to the edge of the bridge, the spacing of the yokes is equal to the distance between the successive ribs 5, carried either by the same panel 1, or by two adjacent panels assembled. In the direction perpendicular to the edge of the bridge, the spacing of the yokes is such that each rib is supported by at least one yoke, preferably at least two.

By acting on the levers 22, the support plates 18 are placed in the upper position. We act on actuator nuts 25 to bring the support plates to a height suitable for correct leveling of the formwork panels they will have to carry.

The panels 1 are then put in place by making them rest by their ribs 5 on the support plates 18. This positioning is done, normally, with the crane 28 of the site.

The panels 1 are then joined together using screws inserted in the holes 4. This has the effect of constituting a continuous and sealed formwork surface, substantially horizontal, that is to say with possibly a slight inclination, complies with the instructions of the owner, weak enough to allow the pouring of concrete. This joining of the panels also has the result of allowing subsequent movements of the formwork in a single block, as will be seen below.

Concrete is then poured. It will be observed that the weight of the concrete, to which is added the much lower weight of the formwork, is transmitted to the shoring structure via the support plate 18, the cam 20 and its shaft 21, as well as the yoke 12 and the rod 24. These parts are calculated accordingly, in particular the shaft 21.

After setting the concrete, to proceed with the formwork, it is enough to actuate the levers 22 to lower the cam 20 and the support plates 18, until the plates 5 rest on the rollers 15 via the ribs 5. It will be observed that these rollers only have to support a very low load, of the order of a hundredth of what the screed must support when the weight of the concrete is felt.

The formwork, as a whole, is then moved towards the edge of the bridge, using winches or jacks bearing on the shoring structure. When a first row of panels has passed the edge of the bridge, that is to say that it is no longer below the deck 29 which has just been poured, these panels are separated from the rest of the formwork, and at the same time, these panels are separated from the rest of the row. The operation can start before the end of the trip. Using the crane 28, the panels are easily removed. If desired, several panels can be removed from the row at the same time, and only separated from the ground.

The operation consisting in advancing the formwork is then repeated until a row is cleared, then the panels of this row are removed using the crane, until the formwork is completely dismantled.

The shoring structure can then be dismantled in a known manner. Its dismantling can also begin before the end of the formwork removal.

The invention is susceptible of numerous variants, without departing from its scope. For example, the cam device for moving the support plate can be replaced by a system with horizontally sliding corners, or by a system with screw jacks or the like. The method of fixing the panels together can also be different from that described, and include, for example, quick-clamping systems.

Claims (12)

1. Method for making a concrete structure having a roughly horizontal lower surface and at least partly separated from the ground, such as a bridge deck, this method comprising the establishment of a shoring structure (9) resting on the ground, laying on this frame formwork panels (1) whose upper surface is roughly horizontal, adjusting the exact position of the formwork elements using lifting means interposed between the frame shoring and the formwork panels, pouring the concrete onto these formwork elements and removing the formwork panels and the shoring frame after the concrete has set,
characterized in that: a) shuttering panels (1) are used which are integral on the one hand with means (3, 4) to secure adjacent panels together and on the other hand with straightening stiffening elements (5), having the form of beams, and parallel to each other; b) there are provided between the shoring structure (9) and the formwork panels (1), rollers (15) or sliding surfaces capable of cooperating with said stiffening elements to horizontally move the assembly formed by the formwork panels joined together over a limited distance; c) after the setting of the concrete, it is stripped and then the said set is moved until at least one formwork panel is beyond the concrete structure (29) which has been poured and set; d) this formwork panel is separated from other formwork elements and removed; e) operations c) and d) are repeated until all the shuttering panels have been removed; f) then dismantling the shoring frame. 2. Method according to claim 1, characterized in that it comprises the use of formwork panels (1) provided, on their underside, with a rigid frame (2) equipped with fastening means such as screws and nuts with the similar frame of an adjacent panel, and at least one rectilinear reinforcement (5), parallel to one of the sides of the frame, and in that the panels are placed with these reinforcements parallel to each other and directed towards the place where all the formwork panels will be dismantled. 3. Method according to one of claims 1 or 2, characterized in that interposed, between the shoring structure (9) and the formwork panels (1) devices (12) comprising a support (18) movable between a first position where it can cooperate with the stiffening elements (5) to support a formwork panel, and a second position, where it allows cooperation between the rollers (15) and the stiffening elements. 4. Method according to claim 3, characterized in that devices (12) are used in which the passage of the support (18) from one position to the other is made using a cam. 5. Method according to claim 3, characterized in that devices (12) are used in which the passage of the support (18) from one position to the other is obtained using wedges. 6. Method according to one of claims 1 to 5, characterized in that in step d), a group of formwork elements is separated from the rest of the formwork, this group is removed, and the disassembly is completed with ground. 7. Formwork panel specially intended for implementing the method according to one of claims 1 to 6, characterized in that it comprises:

- a plate (1) of unfilled cell material, with two layers of coating of waterproof material;
- reinforcing ribs (5) of material with unfilled cells;
a rigid frame (2) on the edges of the plate, this frame carrying means of connection with the frames of adjacent panels,
the plate, the ribs and the frame being integral with each other. 8. Panel according to claim 7, characterized in that the unfilled cell material has a structure of the honeycomb type with cells perpendicular to the plane of the plate. 9. Panel according to claim 7, characterized in that the material with unfilled cells is a plastic foam with firm pores. 10. formwork and bearing device, specially intended for implementing the method according to one of claims 1 to 6, characterized in that it comprises:

- a yoke (12) formed of a base (13) and two sides (14);
- a support plate (18) movable in the yoke perpendicular to the base (13);
- A means (22) capable at will of maintaining the support plate in a first position away from the base and of letting it move to a second position closer to the base;
- at least one roller (15) mounted in the yoke, with an axis parallel to the base, and the top of which is further away from the latter than the outer face of the support plate in its second position,
and means for connecting the base of the yoke with a support structure, these connection means comprising means for moving the base approximately perpendicular to its plane and a ball joint making it possible to vary within certain limits the orientation of the base with respect to the support structure. 11. Device according to claim 10, characterized in that the means capable of maintaining and allowing the support plate to move comprise a cam (20) mounted in the yoke and acting on the internal face of the support plate (18). 12. Device according to claim 11, characterized in that the cam (2) carries a roller (30) which bears on the support plate (18) when it is in said first position, and is arranged to facilitate movement of the cam to deviate from this first position.

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