EP0603060B1 - Prefabricated plate and method for making a bridge using such plates - Google Patents

Abstract

The invention relates to a prefabricated reinforced-concrete plate (8) for making a bridge floor (deck), the unitary span length of which does not exceed 45 m, the bridge including pillars used for bearing two metal girders extending side by side between the pillars in order to support a succession of the said plates. The plate includes through passages in which are anchored nuts for receiving threaded rods capable of resting via one end on the girders in order to constitute screw jacks (15) making it possible to create a sufficient space between the plate and the girders with a view to introducing therein a cement mortar used as a foundation for the plate. <IMAGE>

Description

The present invention relates to a precast reinforced concrete slab used for the production of a bridge deck supported by a metal frame and more particularly of a bridge deck with one or more spans, the unit length of each span n ' not exceeding 45 meters.

Apron bridges supported by a metal framework whose unit span length is less than 45 meters are used for example for the crossing of a highway by a secondary road, and include pillars serving as support for two metal beams s' extending side by side between the pillars, to support a succession of slabs forming the bridge deck (see, for example, FR-A-2 622 907).

In particular in order to protect the upper part of the beams receiving the slabs from corrosion, it is customary to cover the upper part of the latter, before laying the slabs, with a cement mortar which also serves as a base for the slabs. However, this way of proceeding does not make it possible to correct the inclination of the slabs laid on this cement mortar so that the succession of slabs does not generally form a continuous surface, but has notches which should be made up later by pouring. on the slabs of a thick asphalt waterproofing screed.

An object of the invention is to provide an improved prefabricated slab of slabs as well as a method of producing a bridge deck from such slabs, so as to simplify the construction of a bridge deck, and to reduce it the cost.

According to a first characteristic of the invention, the slab has through passages in which nuts are anchored, in order to receive threaded rods capable of resting at one end on the beams to constitute screw jacks making it possible to provide sufficient space. between the slab and the beams in order to introduce a cement mortar serving as a foundation for the slabs, after adjusting the inclination of the slab on the beams.

It is thus possible, by virtue of the invention, to obtain a continuous surface of the bridge deck, which does not require a thick asphalt sealing screed to be poured. Sealing can then be obtained so less costly using synthetic material plates, faster to install.

In a preferred embodiment of the invention, the slab is produced by molding a reinforced concrete block of generally elongated parallelepiped shape, having reinforcements extending outside an opposite front edge and a rear edge of the slab , at least one of the front and rear sections of the slab having a recess providing access from above to the reinforcements of two contiguous slabs arranged front section against rear section, for their connection by pouring a concrete joint in said recess, the front and rear edges having below said recess a projecting edge and a tuck-in edge of generally complementary shapes so that the contiguous rear and front edges of two adjacent slabs constitute a formwork for pouring the concrete joint into said indentation, without the need to bring back a formwork wall from below.

In the case where the line joining the supports of the two beams on the same pillar extends obliquely with respect to the longitudinal axis thereof, which is the case when a secondary road crosses a motorway at an angle, the use of the only known conventional slabs, of rectangular shape, does not make it possible to cover the longitudinal ends of the beams. It is then known according to the prior art to produce a formwork for pouring concrete and forming tailor-made end slabs, which increases the duration and the cost of the site accordingly.

Another object of the invention is to remedy this drawback by proposing tiles making it possible to cover the longitudinal ends of the beams. In one embodiment of the invention, the slabs have a shape of a non-rectangular parallelepiped such that the front and rear edges extend parallel to said line joining the supports of the two beams on the same pillar.

According to an advantageous characteristic of the invention, the slab has vertical stops on the underside for laterally docking at least one of the two beams with a view to centering the slab. Preferably, these vertical stops are received removably in sockets anchored in the slab.

According to another advantageous characteristic of the invention, the slab comprises on at least one of its front and rear sections two docking stops, each arranged in the vicinity of a lateral face of the slab and in front of the reinforcements, proper to avoid impacts from slabs of slabs.

According to another advantageous characteristic, the slab comprises connection cells in which the reinforcements extend naked, arranged so as to come opposite the beams when the slabs are laid on them, two of these cells also opening onto a edge of the slab in order to have a sufficient connection surface with the beams without weakening the slab.

The present invention also relates to a method of implementing the aforementioned slabs to make a bridge.

• . construire des piliers de support servant d'appui à deux poutres métalliques s'étendant côte à côte entre les piliers,
• . disposer les poutres sur lesdits piliers de support,
• . préfabriquer des dalles de hourdis conformes à l'invention,
• . disposer sur la longueur de chaque poutre, deux joints d'étanchéité espacés entre eux,
• . souder sur les poutres des goujons verticaux en vue de leur connexion avec les armatures des dalles de hourdis,
• . poser lesdites dalles de hourdis, équipées des tiges filetées et des butées verticales sur les deux poutres,
• . actionner les vérins à vis pour obtenir une surface continue de tablier de pont,
• . introduire un mortier de ciment servant d'assise aux dalles dans l'espace formé entre les dalles, les poutres et les joints d'étanchéité,
• . introduire un mortier de ciment dans les renfoncements formés entre les dalles en vue de la connexion des armatures des dalles adjacentes entre elles,
• . réaliser une chape d'étanchéité pour le tablier,
• . réaliser un revêtement servant de surface de roulement.

According to a characteristic of the method according to the invention, it comprises the steps consisting in:

• . build support pillars serving as support for two metal beams extending side by side between the pillars,
• . placing the beams on said support pillars,
• . prefabricating slabs of slabs according to the invention,
• . place along the length of each beam, two gaskets spaced apart,
• . weld vertical studs to the beams in order to connect them to the reinforcement of the slabs of slabs,
• . lay said slabs of slabs, fitted with threaded rods and vertical stops on the two beams,
• . operate the screw jacks to obtain a continuous surface of the bridge deck,
• . introduce a cement mortar serving as a foundation for the slabs in the space formed between the slabs, the beams and the seals,
• . introduce a cement mortar into the recesses formed between the slabs in order to connect the reinforcements of the adjacent slabs to each other,
• . make a sealing cap for the deck,
• . make a coating serving as a rolling surface.

• la figure 1 est une vue en élévation latérale d'un pont permettant la traversée d'une autoroute par une route secondaire,
• la figure 2 est une vue de dessus schématique partielle du pont représenté sur la figure 1,
• les figures 3 et 4 sont des vues schématiques en perspective d'une dalle de hourdis conforme à l'invention, selon deux orientations opposées,
• la figure 5 est une vue en coupe schématique dans un plan contenant l'axe d'un vérin à vis et perpendiculaire à la direction longitudinale d'une poutre,
• la figure 6 est une vue en coupe schématique prise au niveau des alvéoles de connexion dans un plan perpendiculaire à la direction longitudinale d'une poutre,
• la figure 7 est une vue en coupe schématique prise dans un plan contenant l'axe d'une butée verticale de la dalle et perpendiculaire à la direction longitudinale d'une poutre,
• la figure 8 est une vue en coupe schématique prise dans un plan contenant l'axe d'une butée d'accostage de la dalle et parallèle à la direction longitudinale d'une poutre.

Other characteristics and advantages of the present invention will appear on reading the description which follows, of a non-limiting embodiment of the invention, and on examining the appended drawing in which:

• FIG. 1 is a side elevation view of a bridge allowing the crossing of a highway by a secondary road,
• FIG. 2 is a partial schematic top view of the bridge shown in FIG. 1,
• FIGS. 3 and 4 are schematic perspective views of a slab of slabs according to the invention, in two opposite directions,
• FIG. 5 is a schematic sectional view in a plane containing the axis of a screw jack and perpendicular to the longitudinal direction of a beam,
• FIG. 6 is a schematic sectional view taken at the level of the connection cells in a plane perpendicular to the longitudinal direction of a beam,
• FIG. 7 is a schematic sectional view taken in a plane containing the axis of a vertical abutment of the slab and perpendicular to the longitudinal direction of a beam,
• Figure 8 is a schematic sectional view taken in a plane containing the axis of a docking stop of the slab and parallel to the longitudinal direction of a beam.

FIG. 1 shows a bridge referenced 1 as a whole, with two spans, the unit length 1 of each span not exceeding 45 meters, the bridge being used for example for crossing motorway lanes 2 by a road secondary 3. The deck 1 comprises an apron 4 resting on a metal frame itself supported at its longitudinal ends by pillars or abutments 5a, 5b and in the middle by one or more pillars; only one pillar 6 has been shown in the figures, for the sake of clarity of the drawings. The foundations of the abutments 5a, 5b and of the pillar 6 have also not been shown for the sake of clarity of the drawing. Preferably, as shown in FIG. 1, the framework of the bridge rests on the abutments 5a and 5b and on the pillar 6 by means of jacks or support devices 7 constituting temporary supports allowing the compression of the bridge during manufacture, in a known manner and as will be explained below.

We referenced in Figure 2, which is a partial schematic top view of the bridge shown in Figure 1, by A the axis of the highway and R the axis of the secondary road. It is noted on examining FIG. 2 that the axes A and R do not intersect, in the particular embodiment described, at right angles, but at an angle. The deck 4 comprises a succession of slabs of slabs 8 in accordance with the invention and arranged side by side on two metal beams 9 of the framework of the bridge. The beams 9 extend parallel to the axis R of the secondary road and rest by their longitudinal ends on the abutments 5a and 5b, not shown in Figure 2 and oriented parallel to the axis A of the highway, the supports respective 10a and 10b of the beams 9 on the two abutments 5a and 5b being offset axially on the axis R. More specifically, the supports 10a and 10b are respectively arranged on each abutment 5a, 5b along a line L extending parallel to the axis A of the highway. The framework of the bridge also usually comprises spacers, not shown, extending between the two beams 9. The beams 9 conventionally have a cross section in the shape of 1, comprising horizontal lower and upper flanges connected by a vertical core. The slabs of slabs 8 have, seen from above, a shape in parallelogram, not rectangle in the case of the embodiment of FIG. 2, delimited by a front edge 11 and a rear edge 12 opposite, extending parallel to the axis A, and by opposite lateral faces 13, parallel to the axis R. The slabs 8 are arranged on the beams 9 front edge 11 against rear edge 12.

There is shown in Figures 3 and 4, in perspective, schematically and in opposite directions, a slab of slabs 8 in isolation. According to the invention, the slab of slabs 8 has a lower face 14 or underside provided with screw jacks 15 capable of resting on the upper flange of the beams to provide a space allowing the introduction of a cement mortar between the slab of slabs and beams, as will be explained below. More specifically, the slab of slabs 8 comprises two pairs of jacks arranged to bear respectively on each beam 9 so as to allow adjustment of the height and the inclination of the slab on the beams.

According to a characteristic of the invention, the screw jacks 15 each consist of a nut housed in a through passage of the slab and of a threaded rod disposed in this passage, engaging the nut. There is shown more precisely in Figure 5 such a screw jack 15. There is referenced 17 a through passage, extending inside a sheath 17a, preferably vertically, that is to say perpendicular to the plane of the lower face 14, reference 18 is a nut embedded in the concrete of the slab at the lower part of the passage 17, and reference 19 is a threaded rod engaged in the nut 18, provided at its lower end with a spherical head 21 resting on the surface 20a of the upper flange 20 of the beam 9. Preferably, as shown, the nut 18 is fixed by its lower edge on a metal plate 22 arranged parallel to the plane of the lower face 14 of slab 8 and flush with the free surface thereof, and comprising sealing tabs embedded in the concrete of the slab. More specifically, the plate 22 comprises two sealing lugs 23 symmetrically opposite with respect to the axis of the rod 19 and diverging in the concrete of the slab 8 away from the plate 22.

If we refer again to Figures 3 and 4 we note that the slab of slabs 8, in reinforced concrete, includes reinforcements extending bare outside the front sections 11 and rear 12 in order to ensure, by covering the reinforcements between two successive slabs, the continuity of the longitudinal reinforcement (along the R axis) of the bridge deck 4. More particularly, in the embodiment described, the front edge 11 has at its upper part a recess 30 opening onto the upper face of the slab, of generally parallelepiped shape, bordered laterally by two walls 31 and lowerly by an edge 40 constituting the lower edge of the slab, the edge 40 having a generally convex profile towards the outside and projecting in front of the side walls 31. The recess 30 delimits a volume in which two bare rows 34 and 35 of horizontal steel frames extend, oriented parallel to the side faces 13. The edge 40 which extends in front of the frames 34 and 35 is interrupted longitudinally in two places to form two notches 41 each located respectively above a beam 9 and serving for the connection of the reinforcements of the slab with vertical studs welded to the upper flange of the beam. The depth of the notches 41, measured along the longitudinal axis of the beams 9, is preferably equal to that of the recess 30. Inside the notches 41 lie bare horizontal reinforcements of the slab, some oriented parallel to the faces lateral 13 and the others parallel to the longitudinal direction of the slab, that is to say parallel to the front and rear edges. Stiffening ribs 42 extend laterally on either side of each of the notches 41 in the dihedral angle formed by the edge 40 and the bottom of the recess 30, in order to stiffen the edge 40 at the notches 41. The slab of slabs 8 has on its rear edge 12 two rows of horizontal frames 51 and 52 oriented parallel to the lateral faces 13. The rear edge 12 has at its lower edge a tucked edge 53 of profile generally complementary to that of the edge 40 so that the contiguous front 11 and rear 12 sections of two adjacent slabs constitute a formwork for the pouring of a concrete joint between these slabs, serving for the connection of the reinforcements of two adjacent slabs, without the need to add a formwork wall by in below, as will be explained below. It will be noted that in addition to the notches 41, the slab 8 comprises connection cells 55 opening onto the lower and upper faces of the slab and inside which extend the bare frames, these cells being arranged on the slab for come opposite the upper sole of the beams 9 with a view to connecting the reinforcements of the slab with the metal beams 9, by means of vertical studs welded to the upper sole of the beams 9. In the embodiment described on the figures, each slab of slabs 8 comprises two pairs of connection cells 55 arranged to come respectively opposite the two beams 9. We could, without departing from the scope of the invention, replace the notches 41 with a solid part and have an additional connection socket located behind the front section 11. However, the creation of an additional socket at center of the slab would decrease its strength.

According to another advantageous characteristic of the invention, the slab of slabs 8 is provided on its lower face 14 with vertical stops 60 arranged in order to laterally dock one at least of the two beams 9 and center the slab on them , during installation. Preferably, as shown, the slab comprises two pairs of vertical stops 60, the two stops of the same pair being arranged to come into abutment respectively on the inner and outer lateral edges of the upper flange of the same beam 9. On FIG. 7 shows more precisely a vertical stop 60. This preferably consists, as shown, of a foot 60a of frustoconical shape, engaged at its base, in a removable manner and by means of a threaded rod, in a socket 60b embedded in the body of the slab.

According to another advantageous characteristic of the invention, the slab 8 has horizontal docking stops capable of preventing impacts from the slabs of the slab. Preferably, as shown in FIG. 3, the slab 8 comprises two docking stops 70 protruding in front of the side walls 31 and in front of the frames 34, 35, along the longitudinal axis of the beams 9.

If we now refer to Figure 8 which is a sectional view taken in a plane parallel to the side faces 13, we note that, in the embodiment described, the docking stop 70 is constituted by a block of concrete molded on a threaded rod 71 retained in a socket 72 anchored in the body of the slab. The plane of the section of FIG. 8 contains the axis of the threaded rod 71. It will also be noted on examining FIG. 8 that the edge 40 has three successive sides each inclined differently from the vertical, in particular a pan upper 40a directed towards the outside of the slab and downwards, a vertical intermediate panel 40b then a lower panel 40c directed towards the interior of the slab and towards the bottom. The tucked edge 53 also has three sides, including an upper section 53a parallel to the section 40a, an intermediate vertical section 53b, and a lower section 53c parallel to the section 53a. A gasket 59 known in itself is disposed between the upper panels 53a and 40a to seal between the edges 40 and 53 engaged one inside the other.

The construction of a bridge deck using prefabricated slabs according to the invention is preferably carried out in the manner which will be described below.

The construction of abutments 5a and 5b and of the pillar 6 is carried out in a conventional manner, known to those skilled in the art, and therefore will not be described, as will the manufacture of slabs of slabs 8. The beams 9 are provided on their upper sole 20 and over their entire length, with seals 80 shown in cross section in Figures 5, 6 and 7. These seals 80, whose cross section recalls the shape of a note of music, have a tubular section part 80a extended tangentially and towards a median plane for the beam by a flattened tongue 81 fixed in a manner known per se (gluing for example) on the upper sole 20. The role of these joints 80 will be specified in the following.

The beams provided with the joints 80 are placed, in a manner known per se, on temporary supports constituted by the jacks 7 provided on the abutments 5a, 5b and the pillar 6. The precast slabs 8, and provided with the rods cylinders 19 as well as vertical stops 60 are placed on the beams 9. Of course, to facilitate their handling, the slabs comprise, on their upper face, lifting anchors known in themselves and not shown. The races of the screw jacks 15 are adjusted so as to provide between the upper surface of the sole 20 and the lower face 14 of the slab sufficient space for the introduction of a cement mortar, serving as a base for the slab of slabs 8 on the beams 9 and protecting the upper sole 20 of the beams from corrosion. The screw jacks 15, actuated in a manner known per se, also allow the inclination of each slab to be adjusted so as to obtain a continuous deck surface. Reinforcement rows 51 and 52 of a slab which appear respectively in line with the rows of reinforcements 34 and 35 of an adjacent slab in a recess 30 are welded together so as to ensure the continuity of the reinforcements along the bridge by overlapping the reinforcements. The reinforcements appearing naked in the connection cells 55 and in the notches 41 are connected to the upper flange 20 by means of vertical studs 95 welded to the beams. We then proceed by the introduction, by gravity into the cells 55, of a cement mortar 90 (or of another material without shrinkage) into the space between the sole 20 and the lower surface 14 of the slab and laterally closed by the joints 80, as shown in FIGS. 5 and 6. The cement mortar 90 ensures the continuous seating of the precast concrete slabs on the beams 9. It will be noted that in order to facilitate the flow of this mortar of cement 90, the slabs have, on their lower face grooves 97 whose bottom extends opposite the upper flange 20 of the beams, oriented parallel to the lateral faces 13 and extending longitudinally over the entire width of the slabs. The threaded rods 19 of the screw jacks are then advantageously recovered, as are the vertical stops 60 used for centering. The slabs are then bonded by pouring a concrete joint 100 between the slabs, in the recess 30, by means of the formwork produced by the interlocking of the edge 40 and the tucked edge 53, as well as the concreting of the cells of connection 55. The succession of slabs of slabs 8 is then put in compression edge to edge by actuation of the jacks 7 and unevenness of the temporary supports on the pillar 6, placing on final support on this pillar 6 then placing on final support of the bridge deck at the abutments 5a and 5b. We then proceed to the realization of the sealing cap, advantageously using plastic plates, then we realize an asphalt coating serving as a rolling surface.

Finally, a slab of slabs according to the invention makes it possible to reduce the duration of the bridge construction site, by facilitating the assembly of slabs of slabs on the framework and by eliminating in particular the operations of rectifying the centering of the slabs, of catching up of recess between the slabs, of setting up the formwork wall from below for the keying of the slabs.

Claims (8)

1. A prefabricated bridge slab (8) made of reinforced concrete for building the deck (4) of a bridge (1) of unit span length not exceeding 45 m, said bridge including pillars (5a, 5b, 6) serving as supports for two metal beams (9) extending side by side between the pillars to support a succession of said slabs, characterized in that the slab includes through passages (17) in which nuts (18) are anchored in order to receive threaded rods (19) suitable for resting at one end (21) on the beams to constitute screw jacks (15) enabling sufficient space to be provided between the slab and the beams for receiving cement mortar (90) on which the slabs are seated after adjusting slab inclination on the beams.
2. A slab according to claim 1, characterized in that its bottom face (14) includes vertical abutment members (60) for laterally engaging at least one of the two beams (9) to center the slab.
3. A slab according to claim 2, characterized in that the vertical abutment members (60) are constituted by legs (60a) removably received in sockets (60b) anchored in the slab.
4. A slab according to any one of claims 1 to 3, characterized in that it is made by molding a block of reinforced concrete that is generally in the shape of an elongate parallelepiped, having reinforcing members (34, 35; 51, 52) extending beyond a front end face (11) and an opposite back end face (12) of the slab, at least one of the front and back end faces (11) of the slab having a setback (30) open to the top face of the slab and providing access from above to the reinforcing members of two contiguous slabs disposed front end face against back end face, in order to enable them to be connected together by casting a concrete joint in said setback, the front and back end faces presenting below said setback a projecting edge (40) and a setback edge (53) of generally complementary shape such that the contiguous front and back end faces of two adjacent slabs constitute shuttering for casting a concrete joint in said setback without it being necessary to apply a shuttering wall from beneath.
5. A slab according to claim 4, characterized in that it is in the form of a non-rectangular parallelepiped such that the front and back end faces extend parallel to a line (L) interconnecting the seats (10a; l0b) of the two beams (9) on the same pillar (5a; 5b).
6. A slab according to claim 4 or 5, characterized in that it includes on at least one (11) of its end faces, two engagement abutment members (70) each disposed in the vicinity of one of the side faces (13) of the slab and in front of the reinforcing bars (34, 35, 51, 52), and suitable for avoiding shocks between the end faces of the slabs.
7. A slab according to any one of claims 4 to 6, characterized in that the slab includes connection recesses (41, 55) into which the reinforcing bars extend bare, disposed so as to overlie the beams (9) when the slabs are placed thereon, two of said recesses (41) also opening out into one of the end faces of the slab in order to provide sufficient connection area with the beams without making the slab fragile.
8. A method of building a bridge (1) of span length not exceeding 45 m, the method comprising the operations consisting in:

   . building support pillars (5a, 5b, 6) serving as supports for two metal beams (9) extending side by side between the pillars;

   . placing the beams on said support pillars;

   . prefabricating bridge slabs (8) according to any one of claims 1 to 7;

   . placing two spaced-apart sealing gaskets (80) along the length of each beam;

   . welding vertical bolts (95) on the beams for connection with the reinforcement of the bridge slabs;

   . placing said bridge slabs fitted with threaded rods (19) and vertical abutment members (60) for centering on the two beams;

   . actuating the screw jacks (15) to obtain a continuous surface for the deck (4) of the bridge;

   . inserting cement mortar (90) to serve as seating for the slabs;

   . inserting cement mortar in the setbacks formed between the bridge slabs in order to connect together the reinforcement of mutually adjacent slabs;

   . making a sealing cover for the deck; and

   . making a covering serving as the running surface of the bridge.

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