EP1101871A1 - Steel bridge deck and method for the construction of a bridge with such a deck - Google Patents

Abstract

The decking for a metal bridge has the longitudinal beams formed from prefabricated sections which are hollow metal tubes (10) of polygonal cross section. The tube lengths are selected for ease of transport. Adjacent sections of two adjacent beams are connected by cross members (2) also formed of metal tubes. The beams are connected at their upper faces by rigid plates (3). The beams can have a rectangular or trapezoidal sections. An Independent claim is also included for a method of assembly of the bridge.

Description

The invention generally applies to the production of medium-span metal bridges, for example a few dozen meters, but is especially suitable for building bridges temporary for military use or for the rapid reconstruction of a bridge destroy.

During military operations, it is often necessary to carry out works to cross rivers or valleys, or good to quickly rebuild destroyed bridges, at least in part.

These temporary constructions are entrusted to the engineering units. For medium ranges, a few tens of meters, we have often temporary bridges made of easy prefabricated elements to be set up by a team of a few men. This type of bridge called, in France, "Bailey" bridge includes load-bearing elements longitudinal made up of light trusses and elements transverse bearing a deck. Given the large number of elementary parts, the installation of a Bailey bridge is quite long and the result is not very aesthetic but it does not matter in the case of military operations.

However, engineering units have, for some time, brought to operate in regions having undergone a state of war, to reconstruction of infrastructure, in particular crossing, which have often been destroyed. Often only the apron has cut, abutments and batteries remaining in place.

To quickly restore communications, it seems interesting to use the elements of temporary bridges available the army of the country requested but this equipment is often not provided in sufficient number. In addition, the bridges thus reconstructed are intended to remain in place for a long time, until complete reconstruction of the structure and it is not without interest to take care of their external appearance as much as possible.

In addition, the "Bailey" type bridges were designed there several decades to be set up by hand by some men. However, engineering units are currently equipped lifting means, the capacity of which can range widely, for example example up to 4 or 5 tonnes, so it is interesting to change the design of temporary bridges taking into account the possibilities current.

The invention therefore relates to a new bridge deck which, like the previously known removable bridges, is constituted prefabricated elements assembled on site but whose implementation place, using lifting devices, can be particularly fast, such an apron can, moreover, have a greater range than the temporary bridges known so far.

On the other hand, the bridge deck according to the invention has a exterior appearance analogous to that of a bridge constructed in a conventional manner. A temporary bridge according to the invention can therefore be easily transformed into a definitive work.

Moreover, because of its multiple advantages, the invention is not not limited to the construction of temporary bridges but can advantageously be applied to the realization of any work of medium range crossing.

The invention therefore generally applies to the production a metal bridge deck having at least one span resting on two supports, said deck comprising at least two main beams parallel to a longitudinal direction of the bridge and connected by a plurality of transverse spacers spaced from each other, and a transverse decking resting on said main beams longitudinal.

According to the invention, each longitudinal beam is made up of a series of elements assembled end to end of prefabricated metal, each formed by a tubular hollow box with polygonal cross section having at least one upper face plane, said boxes having the same section and each extending over a length compatible with the means of transport and lifting. Of more, the boxes of two adjacent beams are connected two by two by a plurality of spacers each consisting of a metal tube having two ends each provided with fixing means with a side face of a box and said beams are connected, at their part upper, by a plurality of rigid transverse joining elements constituting at least part of the deck and having two ends fixed respectively on the flat upper faces of the two beams.

Advantageously, each box forming an element of longitudinal beam has a quadrangular cross section and, preferably trapezoidal, having two horizontal faces of widths different and two lateral faces inclined symmetrically with respect to to a vertical median plane of the box.

In a first embodiment of the invention, the elements cross junction consist of a series of spaced sections from each other and extend transversely over a length at less equal to the distance between two beams, said sections having each two ends respectively fixed on the upper faces planes of the corresponding caissons of the two beams.

Preferably, the joining profiles are spaced apart constant distance corresponding to the width of a wooden crosspiece placed between two neighboring profiles and resting on the upper faces planes of the corresponding boxes of the two longitudinal beams, one temporary decking thus being made up of a series of crosspieces laid next to each other.

According to another advantageous characteristic, the apron includes a series of corrugated panels extending between two beams longitudinal and resting on the upper faces of the boxes corresponding to said beams, said panels being contiguous and constituting a lost formwork for pouring a concrete slab forming the decking of the deck.

In the case where the temporary decking consists of sleepers placed between junction profiles, it is possible, after removal of the sleepers, to place, between the two beams, a series of panels corrugated fitting on the profiles and constituting a lost formwork for pouring a concrete slab forming the final decking of the deck.

Advantageously, the flat upper face of each box is provided with upward projecting parts, forming connectors, intended to be embedded in the concrete slab poured on the formwork lost, for securing said slab to the beams longitudinal.

In another embodiment of the invention, the elements cross junction consist of a series of slab elements of concrete intended to be laid contiguously, one after the other, on at least two series of boxes forming at least two beams longitudinal, covering them, each element of the slab being secured, after installation with the corresponding boxes of the two beams, so as to form the decking of the deck.

The invention also covers a number of advantageous characteristics which will be described in more detail by the and which are the subject of the subclaims.

Furthermore, the invention also covers the elements prefabricated for the construction of a bridge deck and a new method of constructing a bridge span comprising such an apron.

However, the invention will be better understood from the following description of certain particularly advantageous embodiments which are described by way of nonlimiting examples and are represented on the attached drawings.

FIG. 1 is a general schematic view, in perspective, of a provisional bridge deck according to the invention.

Figure 2 is a cross-sectional view of the deck.

Figure 3 is a detail view, in cross section, of a box, at a spacer.

Figure 4 is a side view, along line IV, IV of the figure 3, of the connection between two successive caissons.

Figure 5 shows, in elevation, the whole of a beam longitudinal of a bridge deck.

Figure 6 is a top view of a prefabricated slab placed on two longitudinal beams.

Figure 7 is a longitudinal sectional view of the junction between two adjacent slabs.

Figure 8 is a perspective view of the mounting of a slab of end.

Figure 9 shows, in longitudinal section, the junction between a end slab and the end of a longitudinal beam.

FIG. 10 is a detail view, in longitudinal section, of the junction between two successive spans, at the level of a support.

Figure 11 is a schematic perspective view of a box for the casting of a transverse support beam.

Figure 12 is a general view, in cross section partial, of the whole of a bridge pile.

Figure 13 is a sectional view along XIII-XIII of Figure 12.

Figure 14 and Figure 15 illustrate two stages of construction of a bridge according to the invention.

In Figure 1, there is shown schematically, in perspective, four stages of construction of a bridge deck comprising, in the example shown, two traffic lanes A and B and which is represented in section in FIG. 2. Each taxiway is supported by two main longitudinal beams 1, 1 'which are each consisting of a series of tubular boxes 10 fixed end to end butt by welding or bolting and interconnected by spacers 2.

As shown in Figure 3, each box 10 has a quadrangular section, preferably trapezoidal, comprising a upper flat face 11, a lower flat face 12 and two faces lateral 13a, 13b inclined symmetrically with respect to the median plane longitudinal P1 of the box 10. Preferably, the large base of the trapezoid faces upwards, the upper face 11 having a width greater than that of the lower face 12. The thicknesses of the sheets are determined on the basis of the forces to be supported, the lower face 12 normally being thicker than the upper face 11.

As indicated, the bridge deck shown in the figure 1 is specially adapted for the construction of a temporary bridge, in particular by a military engineering unit and is therefore made up entirely of prefabricated elements which can be made in advance and brought to the site. For the construction of a supporting beam, we will therefore have a series of boxes 10 capable of being assembled end to end and spacers 2 provided, at their ends, with fixing means on the lateral faces 13 of the boxes, the number of elements depending on the span of the span to be made and the dimensions of the boxes which are determined according to the means handling available.

In general, the length (L) of each box 10 corresponds to the possibilities of transport by road and, normally, also suitable for transport by rail, air or sea. Indeed, the place of construction being, often, isolated, the last part of the transport will generally be by road. In practice, the caissons 10 will have a length not exceeding 5 or 6 meters so that allow their transport on a road trailer and their handling on the site by a lifting device of the type currently available engineering units whose power is generally 4 or 5 tonnes.

However, to allow immediate adaptation to construction conditions, we will preferably have a stock of elements, in particular of boxes 10 having at least two different lengths (L), for example 2.5 meters and 5 meters so that be able to carry out spans with different spans on site.

Likewise, it will be advantageous to have boxes made at from sheets of different thicknesses depending on the loads and surcharges which depend on the nature of the traffic. In particular, if the boxes are made in advance it is interesting to vary the thickness (e) of the lower face 12 so that it is possible to choose the advance of the boxes likely to resist the applied loads, taking into account the span of the span to be made and the position of the box in relation to the supports.

However, to be able to assemble the boxes end to end, their external dimensions, i.e. their height (H) and the width (11, 12) faces, respectively upper and lower, will be, normally, the same so that, at assembly, the walls will be arranged as an extension of each other, even if their thickness, in particular that of the underside, may vary.

In practice we may, for example, have several ranges of boxes for which the height (H) of box 10 can be 600, 700, 800 and 900 mm, respectively. For each height, we will have 3 or 4 types of boxes for which, for example, the thickness (e) of the underside may vary from 20 to 75 mm. So the first range of boxes with a height of 600 mm will allow to make spans with a span of 10 to 20 m while the latest range, having a height of 900 mm, will allow to realize spans with a range of 20 to 25 m.

Of course, these dimensions will be chosen so as to optimize the possibilities by using a reduced number of boxes as possible to deal with all cases of bridge construction of medium range, i.e. normally between 10 and 30 meters.

It should be noted that the design of the span, in particular the low number of elements and their simplicity, allows them to be assembled very simple way, for example by bolting. Therefore, it is possible dismantle the bridge to recover the elements, for example after reconstruction of a permanent bridge. In addition, a construction by bolting or riveting is easier to perform and does not require a personnel as specialized as for welding, which is particularly advantageous for military applications.

The assembly of the elements will be carried out conventionally in metallic construction. For example, in the example shown on the Figure 3, each end of a spacer tube 2 is provided, in its median plane, of a fixing plate 21 which is applied to a gusset 22 fixed, in a transverse plane, on the lateral face 13 of the box 17, the flat 21 and gusset 22 being provided with orifices which come into alignment for installing fixing bolts.

As shown in Figure 1, for the realization of a span of temporary bridge according to the invention, so we will bring to the site a certain number of box elements prepared in advance and which are joined end to end to form a longitudinal beam 1, some boxes which may have a different length (L) so as to produce a span of desired length.

If the length of this span is not too great and corresponds to the possibilities of the lifting device available, can assemble the boxes on the ground so as to constitute a beam of desired length and lift it as a block to place it on the supports. In this case, two longitudinal beams 1, 1 ′ will be placed, one next to the other, which are then connected by a number of spacers 2.

It should be noted that the trapezoidal section of the beam reduces the risk of spillage and therefore facilitates installation.

But we can also push the beams longitudinally slip or roll on their lower soles.

Thus, in the example shown in Figure 1, we realize everything first a first span element consisting of two boxes 10, 10 ' connected by two spacers, respectively a central spacer 2a and an end spacer 2b.

Having placed this first element on a launch site placed at the desired level, then fixed on the ends of the two boxes 10, 10 'the following boxes 10a, 10'a connected by a spacer 2c. We can thus gradually build the two beams longitudinal 1, 1 'of the span which rest, for example on rollers, by their lower faces 12 and are pushed longitudinally as the construction proceeds to achieve the entire span.

As indicated, the adjacent elements 10, 10a, can be assembled end to end by bolting, which allows, thereafter, dismantle the apron to recover the elements.

However, it is more advantageous to use the mode assembly by prestressing shown in Figures 3 and 4.

In this case, each box 10 forming an element of a longitudinal beam has four parts at each end massive 23 welded, on the outside, at the four corners of the box the soles 11 and 12 of which have been extended laterally. These parts massive 23 are each drilled with a bore 24 so that the parts 23a, 23b placed, respectively, at the opposite ends of two adjacent beams 10a, 10b are applied one on the other, the bores 24a, 24b being aligned. We can then thread into these bores aligned high yield strength prestressing bars 25 which are energized and blocked, for example, by prestressing 26.

Thus, it is possible to realize, for example on the bank of a river to cross, two longitudinal beams 10, 10 'which are set place between two supports, for example by means of a crane, by pushing or launching.

This first assembly phase I has been shown schematically at the bottom right in Figure 1.

We thus created the supporting structure of a first circulation A and it is possible, if necessary, to build, next to this, a second supporting structure for a second circulation B.

To ensure the rigidity of each supporting structure, the two beams 1, 1 ′ are then secured by joining elements such as that profiles 3 having a length at least a little longer than the distance between the two adjacent beams 1, 1 'and the ends of which are fixed on the upper faces 11, 11 'thereof.

In the case of a temporary bridge, it is then wooden beams 40 possible between profiles 3 example of railway sleepers, which thus form a deck provisional 4.

This phase II is shown at the top right of Figure 1. We were able to quickly and economically build a span of temporary bridge by simply using a lifting device of a power of a few tonnes.

However, according to another advantage of the invention, the bridge temporary thus constructed can be very easily transformed into a bridge final.

For this purpose, after removing the crosspieces 40 forming the decking 4, the space between two adjacent beams 1, 1 ′ is covered series of corrugated panels 31 placed one after the other, as indicated in phase III, bottom left of Figure 1. These panels 31 are provided with transverse corrugations which fit into the profiles junction 3 fixed on the two beams 1, 1 '. This constitutes a formwork lost for the pouring of a slab 41, in a last phase of construction IV shown at the top left of Figure 1. Good of course, before the concrete was poured, adequate reinforcement was put in place above the lost formwork 31.

However, as indicated, the invention is not limited to construction of temporary bridges but can also be used for make a classic metal bridge.

In this case, the supporting structure consisting of at least two longitudinal beams 1, 1 'connected by spacers 2 is covered by a concrete deck made up of prefabricated slabs which are secured to the upper faces of the longitudinal beams 1, 1 ' so as to ensure the rigidity of the structure.

As before, each longitudinal beam 1, is consisting of a series of prefabricated boxes 10 fixed end to end, by example by means of prestressing bars, as shown in figure 4.

These boxes are made in advance and it is advantageous to have several lengths assembled judiciously according to the distance between supports. For example, in the embodiment shown in Figure 5, the beam 1 is constituted, in its most large part of boxes 10a having a length, for example, of 3.50 meters, and is completed, by a number of boxes more short 10b, 10c having lengths of 2.5 meters and 1 meter. Of end boxes 10d, 10e are placed at both ends.

As indicated, the two longitudinal beams 1,1 'are connected by spacers 2. However, as the beams are permanently joined by concrete slabs, the number spacers may be reduced and it may be sufficient, for example, to simply place a spacer at each end of the span and a or two spacers in the central part.

In addition, it is interesting to have several types of boxes in which the thicknesses of the sheets, in particular for the bottom sole 12, may vary depending on bending moment supported which depends on the position of the box in the span. Through example, as shown in figure 5, the boxes placed in the part center of the span can have a bottom sole 12 thick larger than for the boxes placed at the ends.

Figure 6 shows, in top view, a slab 5 covering two longitudinal beams 1, 1 'which is shown in section transverse in FIG. 12. The slab 5 advantageously comprises a central part 51 extending between the two beams 1, 1 'and extended, on either side of these by two lateral parts 52 on which sidewalks can be mounted 42.

Figure 7 is a detail view, in section along line I-I of the Figure 6 of the connection between two adjacent slabs. Each slab 5 is provided on its sides with recesses 53 extending over part of the height of the slab so as to leave a lower part in the form of partition 54 forming lost formwork. When placing two slabs adjacent, the partitions 54a, 54b come into contact with one another in limiting a rectangular space made up of the recessed parts 53a, 53b in which stand armatures extend 55. After installation elements, transverse bars 56 are threaded into the frames 55, and the whole is embedded in concrete poured into space 53a, 53b of so as to form a continuous slab.

On the other hand, each slab 5 is provided, at the level of each beam 1, 1 ', of at least one recess 6 which extends over the entire height of the slab 5 so as to open on a part 14 of the upper face 11 of beam 1 on which a plurality of studs 61 have been welded forming connectors. Preferably, there are simply two types of slabs, respectively a common slab such as 5 and a end slab 5 'placed at each end of the span and shown in figure 8. Normally, there is only one type of slab current and the length (I) covered by each slab does not correspond necessarily to the length (L) of the boxes. Therefore, at when studying the span of the bridge to be built, we will determine the location of zones 14 of each beam 1 corresponding to recesses 6 of the slabs and the studs 61 will be arranged on each elementary caisson 10 as a function of its position in the span.

Advantageously, the lower partitions 54 formed on the sides of each slab 5 will be provided, at the level of each beam carrier 1, notches 62, the corresponding area of the face upper 11 of the beam 1 being provided with connector studs 61 of so as to secure the joining, with the beam, of two slabs successive at their junction.

At its end facing the abutment, each beam 1 is ends with a 10d end box which is covered with an end slab 5 'shown in perspective in Figure 8. This end slab is provided, on its side facing the adjacent slab, with a recess transverse 53 and, on its side facing the abutment, a beam of stiffening 57, turned downwards and forming an acroterion. The level of box 10d, the beam 57 is provided with a recess 63 in which extend from connector studs 61, 64, welded respectively to the upper face 11 of the box 10d and on two lateral faces 14 ' formed at the end of the box 10d. So, using formwork it is possible to pour concrete in the recess 63 to complete the transverse beam 57 and ensure the joining of the slab element 5a with the end box 10d.

In the example shown in the figures, the bridge is made up of two spans resting on a pile 7 by means of a beam transverse 8 constituting an intermediate support.

According to another advantageous characteristic of the invention, each intermediate support beam 8 constitutes a keying of joining between the ends of the two spans, which is carried out at inside a box forming a lost formwork and resting on the pile 7.

This box 80, shown in perspective in FIG. 11, has the shape of a trough having a bottom 81, two side walls 82 in which are provided notches 83 whose profile corresponds to that, in cross section, of a longitudinal beam 1, and two end walls 86.

Thus, as shown in Figure 10, the end boxes 10e of two aligned beams 1a, 1b of two successive spans, penetrate by the notches 83, inside the formwork 80. The two ends of the two beams 1a, 1b are provided with connector studs 61, 65 welded, respectively, on the upper face 11 of the box 10e and on a flange 15 fixed to the end of it.

The upper edges of the two lateral faces 82 of the box 80 are covered by the tiles 5a, 5b placed on the ends of the beams 1a, 1b. We can then pour concrete 16 inside the box and up to the upper level of the slabs, so as to create a beam transverse 84 which secures the two spans and the continuity of decking.

This transverse beam 84 rests on the stack 7 by support members 71 which can be of any known type, for example smooth or roller bearings. Preferably, each press 71 slides, with little play, into an opening 85 in profile corresponding, formed in the bottom 81 of the formwork 80 so that the support is made directly on the concrete. Of course, the beam transverse 84 thus formed may be provided with adequate reinforcement, especially in its lower part, to ensure the distribution of the load on supports 71 and in its upper part, for the junction tiles 5a, 5b.

Figures 14 and 15 schematically illustrate the implementation of a bridge according to the invention resting on a pile 7 constituted in the manner shown in detail in Figures 12 and 13.

In the example shown, the bridge constitutes a work of crossing over a two-lane motorway on a platform A. After having prepared the ground and realized this platform, we dig first, to the level we want for foundations, one excavation B1 for the central pile and two excavations B2 for the abutments. Yes the soil is fairly resistant, the foundation of the central pile can be simply consisting of a C1 sole and, optionally, a concrete D pedestal on which elements are placed prefabricated 71 which advantageously consist of boxes superimposed, as shown in Figures 12 and 13. A internal reinforcement secures the assembly to the pedestal D to upper level 73 of stack 7.

Similarly, each abutment may be made up of elements superimposed 74, resting on the sole C2. These elements 74 can have, for example, a U-shape for the maintenance of an embankment made to the desired level.

Then supports 71, 71 'are placed respectively on the upper end 73 of the stack 7, at the upper level 73 ′ of each abutment 70.

The stack 7 is then equipped with brackets 75 fixed so removable and constituting a temporary support for the transverse box 80, the bottom of which is wedged at the desired level on the supports 71.

Meanwhile, the four supporting beams 1 have been produced. each formed by assembling longitudinal boxes 10 joined together, for example, by prestressing.

A lifting device E, for example a mobile crane, traveling on platform A then successively sets up the four longitudinal beams 1, each beam having an end 10d which rests on the support 71 'of the abutment 70 and an opposite end 10e which engages in a corresponding notch 83 of the box transverse 80.

As shown in Figure 15, using the hoist E, the various slabs 5 constituting the decking of the bridge and we can then pour the concrete, on the one hand in the box 80 for constitute the transverse beam 8 bearing on the stack 7 and, on the other hand, in each of the transverse joints 57 between two successive slabs.

A continuous deck was thus produced which may have, in section transverse, the profile shown in Figure 12. The bridge can then be finished with the installation of sidewalks 42, and a border prefabricated 43 supporting a railing.

So we see that, by means of a small number of elements prefabricated metal, we can quickly and economically a bridge span, either for a construction provisional, as shown in Figure 1, either for a final construction, the decking can also be formed of prefabricated elements.

But the invention is obviously not limited to the details of embodiments which have been described by way of simple examples and which could be subject to variations without departing from the scope of protection described by the claims.

For example, it is particularly advantageous to carry out boxes with trapezoidal section, but other shapes could be considered.

The reference signs inserted after the characteristics techniques mentioned in the claims, have the sole purpose of facilitate understanding of these and do not limit them in any way the scope.

Claims (21)

Deck for a metal bridge having at least one span resting on two supports, said deck comprising at least two main beams (1, 1 ') parallel to a longitudinal direction of the bridge and connected by a plurality of transverse spacers (2) spaced apart from one another, and a transverse deck (4) resting on said longitudinal main beams (1, 1 '),
characterized by the fact that each longitudinal beam (1) is formed by end-to-end assembly of a series of prefabricated metal elements each formed by a hollow tubular box (10) with polygonal cross section having at least one flat upper face ( 11), said boxes (10) having the same section and each extending over a length (L) compatible with the means of transport and lifting, as the boxes (10, 10 ') of two adjacent beams (1, 1 ') are connected two by two by a plurality of spacers each consisting of a metal tube (2) having two ends each provided with means (21) for fixing with a side face (13) of a box (10) and that said beams (1, 1 ') are connected, at their upper part, by a plurality of rigid transverse junction elements (3) constituting at least part of the decking (4) and having two ends fixed respectively on the upper faces planes (11) of c aison (10, 10 ') of the two beams (1, 1'). Bridge deck according to claim 1, characterized by causes each box (10) forming a longitudinal beam element (1) has a quadrangular cross section having two faces horizontal, respectively upper (11) and lower (12), connected by two lateral faces (13). Bridge deck according to claim 1, characterized by makes each box forming a longitudinal beam element has a trapezoidal section having two horizontal faces (11,12) of different widths and two inclined side faces (13) symmetrically with respect to a vertical median plane of the box. Bridge apron according to one of claims 1, 2 3, characterized in that the transverse joining elements are consisting of a series of sections (3) spaced from each other and extending transversely over a length at least equal to the distance between two beams (1, 1 '), said sections (3) each having two ends fixed respectively on the flat upper faces (11) boxes (10) corresponding to the two beams (1, 1 '). Bridge apron according to claim 4, characterized by the fact that the joint profiles (3) are spaced a constant distance corresponding to the width of a wooden crosspiece (40) placed between two neighboring profiles (3) and resting on the flat upper faces (11) of the boxes (10) corresponding to the two longitudinal beams (1, 1 '), one temporary decking (4) thus being constituted by a series of crosspieces (40) placed one next to the other. Bridge apron according to one of claims 1 to 5, characterized in that it comprises a series of corrugated panels (31) extending between two longitudinal beams (1, 1 ') and resting on the upper faces (11) of the corresponding boxes (10) of said beams (1, 1 '), said panels (31) being contiguous and constituting a lost formwork for pouring a concrete slab (41) forming the deck decking. Bridge apron according to claim 6, characterized by the fact that the corrugated panels (31) fit into profiles of junction (3) fixed on the two beams (1, 1 ') and constituting elements rigid transverse junction. Bridge apron according to claim 5, characterized by includes a series of corrugated panels (31) extending between two longitudinal beams (1, 1 ') and placed one after the other in fitting onto the junction profiles (3), after removal of the cross members wood (40), said corrugated panels constituting a lost formwork for the pouring a concrete slab (41) forming the final decking of the deck. Bridge apron according to one of claims 6 and 8, characterized by the fact that the planar upper face (11) of each box (10) is provided with upward projecting parts, forming connectors (61), intended to be embedded in the concrete slab (41) casting on the lost formwork, for securing said slab (41) with the longitudinal beams (1, 1 '). Bridge apron according to one of claims 1, 2, 3, characterized in that the transverse joining elements are consisting of a series of concrete slab elements (5) intended to be placed contiguously, one after the other, on at least two sets of boxes forming at least two longitudinal beams (1, 1 '), in covering these, each element of the slab (5) being secured, after installation with the corresponding boxes (10) of the two beams (1, 1 '), so as to form the decking of the deck. Bridge apron according to claim 10, characterized by fact that each slab element (5) is provided, on each part covering a box (10), at least one recess (63) in which penetrate, when the element is installed, projecting parts forming connectors (61), fixed on a corresponding area of the face upper plane (11) of the box (10), for securing the element slab (5) with the boxes (10) which it covers, by pouring into said recess (63) of a concrete in which said connectors are embedded (61). Bridge apron according to one of the preceding claims, characterized in that the longitudinal beam elements (1, 1 ') in the form of hollow boxes (10) are joined two by two by welding of their adjacent ends. Bridge apron according to one of the preceding claims, characterized in that the longitudinal beam elements (1, 1 ') in the form of hollow boxes (10) are joined two by two by bolting of their adjacent ends. Bridge apron according to one of the preceding claims, characterized by the fact that each beam-shaped element box (10) is provided, at each of its ends, with solid parts (23) welded to the box (10) and each pierced with a bore (24) and that, when placing the boxes (10) end to end for the constitution of a longitudinal beam (1), the massive pieces (23a, 23b) of two consecutive boxes (10a, 10b) are placed one after the other to the establishment of a means (25) for securing the caissons consisting of a prestressing bar (25) passing through the bores (24a, 24b) aligned and energized. Bridge apron according to one of the preceding claims, characterized in that, at one end of a span, the beams main longitudinal rests on a support (7) of the bridge by through a transverse beam (8) consisting of a box (80) having a bottom (81) resting on the support (7) of the bridge, two side walls (82) and two end walls (86), said side walls (82) being provided, at each longitudinal beam (1), with a notch (83) having the same profile as the longitudinal beam (1) in section transverse, so as to allow the nesting of an extreme part (10th) of each longitudinal beam (1) in a notch (83) corresponding to the transverse box (80), partially penetrating therein, said box (80) forming a lost formwork which is filled, after the installation of all the beams, concrete of keying (16) so to make a transverse beam (8) secured to the ends of the set of longitudinal beams (1). Bridge deck according to claim 15, characterized by fact that each longitudinal beam (1) is provided, at its end (10th) penetrating into the transverse box (80), projecting parts forming connectors (65), for securing the longitudinal beam (1) with the transverse beam (8) poured into the box (80). Bridge apron according to claim 16, characterized by causes each intermediate support (7) of the bridge to carry a box transverse (80) having two side walls (82) provided with notches (83) interlocking the ends of the longitudinal beams (1) of two successive spans, so as to ensure, after pouring the concrete (16) in the transverse box (80), the joining of the two spans extending on either side of the transverse beam (8) thus produced. Method of constructing a bridge span based on two separate supports, characterized by the fact that it is carried out in advance a plurality of longitudinal beam elements each consisting a tubular box (10) of polygonal cross section, having at at least two parallel planar faces, respectively an upper face (11) and a lower face (12), said boxes (10) having a weight and a length (L) compatible with the lifting and transport, a plurality of cross-pieces (2) each consisting of a metal tube (2) having two opposite ends, it brings said boxes (10) and spacers (2) at the place of construction, this the latter comprising at least two supports (7) made in advance, assembles said boxes (10) end to end by joining their adjacent ends so as to form at least two beams longitudinal (1, 1 ') each consisting of a series of boxes (10), the longitudinal beams thus formed are put in place, so as to rest them, at two ends, on two spaced supports (7, 70) of the bridge, said longitudinal beams (1, 1 ') being joined together by at least two crosspieces (2) which are fixed, each by two opposite ends (21), respectively on two lateral faces (13) opposite two boxes (10, 10 ') placed at the same level on the two beams (1, 1 ') and a deck (4) is produced covering said longitudinal beams at least part of which consists of plurality of rigid transverse junction elements (3, 5) distributed over the entire length of the span and each extending at least over the distance separating the two longitudinal beams (1, 1 '), each junction element (3, 5) being fixed on the upper faces (11) of the two longitudinal beams (1, 1 '). Method according to claim 18, characterized in that that the joining elements are metallic profiles (3) having each two ends fixed, after installation, on the upper faces (11) of the two longitudinal beams (1, 1 '), that said sections (3) are regularly spaced apart by a distance substantially equal to the width a wooden beam (40) of the railroad cross type and which places a crosspiece (40) in each interval between two sections, so as to constitute a temporary decking (4). Construction method according to claim 19, characterized in that, to replace the temporary decking (4) with a definitive decking, we remove the wooden sleepers (40), we cover at least the space between two longitudinal beams of contiguous panels (31) provided with grooves fitting into the junction profiles (3), and a concrete slab (41) is poured onto the surface formed by the faces upper (11) longitudinal beams (1, 1 '), with said panels (31), the latter constituting a lost formwork for casting of the slab (41). Method of constructing an apron according to claim 18, characterized by the fact that a plurality is produced in advance concrete slab elements (5) each having an elementary length (I), and each comprising, at each longitudinal beam (1, 1 '), at least one recess (6, 63) extending over the entire height of the slab (5) so as to open onto an area (14) of the beam (1) provided with projecting parts forming connectors (61, 64, 65), and that, after placing in place of two longitudinal beams (1, 1 ') connected by crosspieces (2), one places on the upper faces (11) of the two beams (1, 1 ') a series of adjoining elementary slabs (5) so that the recesses (6, 63) of each slab (5) cover at least one area of junction provided with connectors (61, 64, 65) of each beam longitudinal (1), then a concrete (16) is poured into said recesses (6, 63) so as to ensure the joining of each slab element (5) with the two longitudinal beams (1, 1 ').

Images