EP1065316B1 - Composite steel-concrete bridge- or walk way structure, especially bridge with double composite beams under the deck - Google Patents

Abstract

The structure consists of at least one hollow steel support (2) for a concrete cover slab (1), the support being totally closed, apart from its ends, and having its inner cavity filled with a hydraulic binding agent (11) such as high performance concrete. The supports can be two in number, located beneath the roadway (5) or to the sides of the bridge above the roadway. Each support can be made, for example, from two I-section beams welded together to form parallel sole plates (12), with the beam webs forming the side walls (13). The material used for the supports can be general structural steel, steel with a high elastic limit, or structural steel with a high resistance to atmospheric corrosion.

Description

The invention relates to the technical field of bridges or bridges to metal frame.

• l'excellent rapport poids/ performance du matériau acier ;
• la rapidité d'exécution.

The main advantages of the metal frame are:

• the excellent weight / performance ratio of the steel material;
• the speed of execution.

We already know in the prior art, different designs of such bridges or gateways.

For example, reference can be made to the following documents: EP-A-501 730, FR-A-2 622,907, FR-A-2,693,491, FR-A-2,616,166, FR-A-2,698,111.

The metal bridges generally include a blanket, a framework and a supporting system, the roof being the part of the bridge that receives the operating costs directly and transmits them to the carrier system via possibly the metal frame conventionally formed by a network longitudinal beams (longitudinal members) and transverse beams (bridge pieces).

The carrier system is frequently formed by two main beams connected by spacers and provided with stiffeners.

Recent covers are usually formed by orthotropic slabs or mixed slabs or slabs of reinforced concrete, sometimes with transverse prestressing.

The orthotropic slabs are generally formed of a sheet called sheet metal decking or rolling plate more than ten millimeters thick stiffened in two perpendicular directions, by transverse bridge pieces and by equidistant longitudinal stiffeners called ribs.

Orthotropic slabs have some disadvantages.

In particular, the variation of transverse bending stresses during the passage of heavy vehicles can lead to the appearance of fatigue cracks in decking sheets.

This risk of fatigue is increased by the presence of many welds in the frame.

Moreover, the quantity of steel used is high and the adjustment and machining are delicate, so the cover is expensive.

The composite slabs comprise a continuous sheet connected to a slab of concrete, this sheet forming the lower reinforcement of the slab. The connectors used are most often pistol-welded vertical studs connected at the top by steels.

Mixed slabs have disadvantages.

In particular, they are only suitable for reduced spans, for reasons of shape stability during pouring of concrete.

Reinforced concrete slabs, sometimes with transverse prestressing, are associated with the steel by different connectors, so as to ensure the transmission efforts of the frame and a certain transverse rigidity.

The most common connectors are angle irons or vertical studs.

Bridges whose supporting system consists of metal beams and whose the cover is a slab of reinforced concrete are called mixed bridges.

The invention relates more particularly to such bridges or bridges.

In such mixed bridges, the slab can sometimes rest directly on main beams braced by triangulated beams for example, the spacers that can be removed when the bridge span is small.

The slab of the composite bridges can in other cases be in longitudinal support on the main beams and transverse support on the bridge pieces.

The slab of mixed bridges may in other cases be supported on the beams main only, these beams being then bridged.

The usual range of spans for mixed bridges ranges from 30 to 110m for continuous spans and from 25 to 90m for spans independent.

• les bipoutres mixtes qui comme leur nom l'indique comprennent deux poutres reliées le plus souvent :
  • par des pièces de pont pour l'appui transversal de la dalle ;
  • par des entretoises soudées perpendiculairement et à mi-hauteur des poutres, pour des tabliers relativement étroits ;
• les ponts mixtes à caisson :
  • avec dalle en béton en appui sur les parois du caisson et sur des éléments transversaux éventuels ;
  • avec dalle mixte telle que présentée ci dessus, à caisson unique ou multicaissons.

The types of designs of these mixed bridges currently most frequently used are:

• the dual-beams that as their name suggests include two beams most often connected:
  • by bridge pieces for transverse support of the slab;
  • by spacers welded perpendicularly and at mid-height of the beams, for relatively narrow aprons;
• the composite caisson bridges:
  • with concrete slab resting on the walls of the caisson and on any transverse elements;
  • with mixed slab as presented above, with single box or multicaissons.

The invention relates more particularly to dual-girder composite bridges.

For twin-girder composite decks, the beams are most often solid, the core and the soles being joined by four fillet welds.

• leur sensibilité aux instabilités de forme, par déformation inhabituelle par rapport à celles qui peuvent être prévues par la résistance des matériaux classique. En particulier, les chocs liés par exemple au passage d'un convoi hors gabarit conduisent à une plasticité en grandes déformations, difficilement prévisible par calcul. De tels chocs, s'ils n'entraínent pas toujours la ruine de l'ouvrage, provoquent des dégâts difficiles à réparer sans travaux de grande envergure ;
• leur sensibilité à la fatigue, en dépit des normes strictes en vigueur (Eurocodes) ne peut être négligée et ce d'autant que, le plus souvent, des amorces de fissures existent dès la construction de l'ouvrage, par non-pénétration des soudures d'angle par exemple.

These solid-core beams have various disadvantages:

• their sensitivity to instabilities of form, by unusual deformation compared to those which can be predicted by the resistance of the classical materials. In particular, the shocks linked for example to the passage of an off-size convoy lead to plasticity in large deformations, difficult to predict by calculation. Such shocks, if they do not always cause the ruin of the work, cause damage difficult to repair without major work;
• their sensitivity to fatigue, in spite of the strict norms in force (Eurocodes) can not be neglected and this especially as, most often, crack primers exist as soon as the construction of the structure, by non-penetration of the welds angle for example.

The invention relates to a twin-girder composite bridge structure, in particular but not exclusively of twin-beam composite girder bridges not having the disadvantages of bridges of this type known in the art prior.

EP 745 740 discloses a bridge according to the preamble of claim 1.

In particular, the invention discloses a simple dual-girder bridge structure resistant to lateral shocks by oversized convoys for example, this structure avoiding the use of gussets and spacers, the construction said bridge does not otherwise require the stop of traffic on the tracks crossed by the bridge.

For this purpose the invention a bridge as claimed in claim 1.

In one embodiment, the bridge structure comprises two beams placed under pavement.

In another embodiment, the bridge structure comprises two beams placed laterally above the roadway.

Each support beam may be provided with an internal reinforcement. Each beam support can be developed by longitudinal welding of at least two elementary beams.

In a particular embodiment, each support beam is produced by welding of two H-shaped beams so that the support beams have two soles substantially facing each other and parallel between them, connected by two walls of soul substantially perpendicular to the soles and facing each other.

In one embodiment, each support beam is made of high-grade steel elastic and is filled with a hydraulic binder such as concrete, for example concrete high performance.

The support beams are assembled to the roof slab by studs placed in reservations of said slab, a support piece being placed in a reservation of the cover slab, between the upper sole of each support beam and said slab, this support piece being provided with a projecting against said upper sole.

• la figure 1 est une vue en coupe transversale partielle d'une structure de pont mixte bipoutre à poutres sous chaussée, selon un mode de réalisation de l'invention ;
• la figure 2 est une vue de détail d'un mode de réalisation des connecteurs de liaison entre poutre et dalle de couverture ;
• la figure 3 est une vue analogue à la figure 2 d'un autre mode de réalisation desdits connecteurs.

Other objects and advantages of the invention will become apparent from the following description of embodiments, which description will be made with reference to the appended drawings in which:

• Figure 1 is a partial cross-sectional view of a composite girder dual girder bridge structure, according to one embodiment of the invention;
• Figure 2 is a detail view of an embodiment of the connecting connectors between beam and cover slab;
• Figure 3 is a view similar to Figure 2 of another embodiment of said connectors.

We first refer to Figure 1.

A bridge deck, only half of which is shown in cross-section in this figure 1 - the other half being symmetrical with the first half represented - includes a concrete slab 1, roofing, resting on two beams 2.

In other embodiments, not shown, the second half of the bridge is not symmetrical to the first, and / or the concrete slab 1 rests on more than two beams 2, for example three beams 2.

The section plane of FIG. 1 is defined by a first direction D1 substantially horizontal said transverse and a second direction D2 substantially vertical.

A third direction D3 forms with the other two directions a trihedron, this third direction being said longitudinal.

The terms "wide" and "width" will be used with reference to the first direction D1.

The terms "high", "height", "thickness" will be used with reference to the second direction D2.

The terms "longitudinal" and "length" will be used with reference to the third direction D3.

In the embodiment shown, the deck is supported by two beams 2 placed under the floor.

In other embodiments, not shown, the apron is not supported only by a single longitudinal beam, or on the contrary by more than two beams longitudinal.

In still other embodiments, not shown, the two beams are placed laterally above the roadway.

The cover slab 1 is of variable thickness, in the embodiment represented: starting from a lateral longitudinal edge of this slab and going towards the center of it, the thickness increases, reaches a maximum value at the right of each beam 2 then decreases and then remains constant over a certain width of the slab.

A central thickness of 20cm cover slab, for a center distance E of 4.5m beams and side cantilevers 3 of about 2m can be obtained by an embodiment according to Figure 1. An apron width of 8m about is thus obtained.

In the rest of the text, the numerical indications will refer to the dimensioning above, made for a span bridge of the order of fifteen to thirty meters to a two or three span, commonly implemented by example for motorway crossings.

In other embodiments, not shown, the thickness of the slab is substantially constant over its entire width. The slab can be made of concrete conventional.

In one embodiment, the slab is made of high performance concrete, its compressive strength at 28 days being for example greater than 80MPa.

The slab can be prestressed longitudinally, especially when the apron is of great width. Mono strands in the voltage range of 150KN used with a step of 30cm can for example be used, the active anchors being placed alternately on one side and the other of the slab.

In the embodiment under consideration, twelve prestressing cables SEEE 4T15S are provided in sleeves 4.

In the embodiment shown, the cover slab 1 supports, in addition to the road pavement 5, longitudinal passages on the banks of cables 6 of different diameters for the telephone, electrical and other.

A border 7 separates the roadway 5 from the sidewalks 8 under which are placed cable passages 6.

In other embodiments, only one sidewalk is provided and / or a only one of the two sidewalks is placed over cableways.

A railing 9 is placed at the side edge of the sidewalk (s). facing 10 is secured to the longitudinal side faces of the deck.

Now more specifically, the longitudinal beams 2 and their fixing on the cover slab 1.

Each beam 2 is core filled with a rigid material based on binder 11, so-called "binder", or any other material presenting mechanical characteristics comparable to those of such a binder 11.

This binder can be chosen from the group comprising concretes based on Portland cements, blast furnace cements, pozzolanic cements, aluminous cements, high performance concretes, concrete based on resin, fiber concretes and their equivalents.

As will be clear to those skilled in the art, the choice of binder 11 depends, among other things, on the dimensions and efforts to be taken into account for beams 2.

In the embodiment considered, each beam 2 comprises two flanges 12 substantially opposite and horizontal, with a thickness e ₁₂ greater than the width I ₁₃ of the two walls 13 substantially vertical and opposite joining these two flanges 12.

The beams can be formed by assembling two H sections, by example HE 800A, welded together by welding beads longitudinal.

These weld beads being arranged longitudinally are not strongly sensitive to fatigue damage phenomena.

In other embodiments, the beams have sections transverse polygonal, and in particular hexagonal.

In still other embodiments, the two walls of souls 13 are pleated regularly or not.

The materials used for the realization of the beams 2 can be chosen among the group comprising general purpose construction steels (and including those mentioned in standard EN-10-025), high-carbon steels elastic limit (and in particular those defined by EN-10-113), steels of structures with improved resistance to atmospheric corrosion and their equivalents.

In one embodiment, the beam webs and the soles are formed by one and the same steel.

In other embodiments, the cores are made of a material different from soles (eg high tensile steel for soles and general purpose construction steel for souls).

The beams 2 may be provided with an internal reinforcement, the fixing of the stirrups, frames and reinforcement of this reinforcement which can be at least partly internal to the beam 2 so as not to affect the visual appearance.

The presence of this internal reinforcement is optional, this one not being necessary for the joining of the different welded parts of the beam 2. The internal reinforcement is not necessarily connected to beam 2.

The filling of a beam 2 by the binder 11 is generally carried out on the construction site by one of the ends of said beam 2, subsequently called end of filling.

A binder pump is connected by a connection to this filling end, then the binder 11 is placed in the beam 2 by pumping.

In order to facilitate the filling of the beam 2, a vent is provided in said beam 2, this vent being preferably located in height, especially if the profile of the beam 2 is curved.

The workability of the binder used and its confined flow capacity must be be adapted as it appears to those skilled in the art, to ensure the desired filling of the armed beams.

The medium being confined, it is difficult to vibrate the binder. Therefore, we use preferably self-compacting concrete, or at least self-compacting or self-leveling.

It is therefore not necessary for the beams 2 to have holes for filling on their upper surface. The presence of such holes leads in general to a weakening of the metal section, especially in the provisional phase, when the beams are not yet filled with binder. Sizing of the section of the beams must take into account this weakening. The invention therefore solves this problem, the absence of holes reducing otherwise the cost of manufacturing the beams.

However, filling control orifices may be made on the beams 2, these orifices being in no way used for filling said beams 2, and can therefore be of small size.

The filling of these beams can be partial, the role of the binder being mainly to avoid local phenomena of local buckling of the walls souls, still called blistering.

Several concretes, of different nature, can be used for this filling, depending for example on the distribution of the planned service on the length of the beams.

For the apron dimensions mentioned above, the width of the soles 12 was 60 cm, the height of the beams of 79cm, the beams filled with concretes being formed by assembling two sections of HE 800A welded.

We now refer to Figures 2 and 3.

The beams 2 are in the illustrated embodiment attached to the slab of cover 1 by studs 14 such as Nelson studs.

These studs are placed in reservations 15 of the slab 1, in line with the upper flange of the beams and substantially perpendicular to this sole.

These reservations are for example cylindrical and cross the entire thickness of slab 1

A support piece forming renformis 16 or equivalent is provided in a reservation located on the lower face of the slab 1, at the right of the sole upper of each beam 2.

This support piece has a bottom face 17 that is substantially horizontal, the exception of its central portion provided with a projection 18 bearing against the upper flange of the beam 2 placed opposite.

Two seals 19 are placed laterally between the underside 17 of the part 16 and the upper flange of each beam 2.

A binder, not shown, cast in the bookings 15 of the slab allows the assembly of the beams 2 to this cover slab 1.

Two studs or four studs may be provided depending on the loads of service provided.

The bridge structure obtained does not require any reinforcing spacer connecting the support beams below and away from the cover slab nor so ipso facto no reinforcement gusset between spacer and support beams, unlike twin-girder composite bridge structures known in the art prior.

Although deck widths achievable according to the described bridge structure above are quite high, nor is it necessary to bridge pieces connecting the support beams below the cover slab on which the roof slab is based longitudinally.

These bridge parts and spacers generate significant assembly costs, must be designed for a given distance between the support beam and their assembly by welding is causing fatigue damage, in composite bipwort bridges known from the prior art.

Filling steel beams with a binder greatly improves stability of these beams in large deformations, in particular during shocks by oversized convoys.

It also ensures the stability of the souls 13 against the risks of spillage or in the zones in which the system carrying the concentrated loads, as for example the right of the supports on which rests the mixed bridge.

Prefabrication of support beams and reduction of on-site assembly makes it possible not to interrupt or modify the circulation on the paths crossed by the bridge or the bridge, which has the advantage important in the case of crossing large traffic lanes such as highways.

Claims (15)

1. A combined concrete-and-steel bridge comprising a cover slab (1) made of concrete and at least one support girder (2) made of steel, said girder (2) being associated with said cover slab (1) via connectors (14) and being designed to support said cover slab (1), the girder (2) having an internal cavity, said bridge being characterized in that said internal cavity is filled at least in part with a binder (11), and in that it is totally closed except at its ends.
2. A bridge according to claim 1, characterized in that it has at least two girders (2) placed under the deck (5).
3. A bridge according to claim 1, characterized in that it has two girders (2) placed laterally above the deck.
4. A bridge according to any one of claims 1 to 3, characterized in that each support girder is provided with internal reinforcement rods.
5. A bridge according to any one of claims 1 to 4, characterized in that each support girder is formed by longitudinally welding together at least two elementary girders.
6. A bridge according to claim 5, characterized in that each support girder (2) is formed by welding together two H-shaped girders so that the support girders have two soleplates (12) that are substantially facing each other and parallel to each other, and that are interconnected by two web walls (13) that are substantially perpendicular to the soleplates (12) and that are facing each other.
7. A bridge according to any one of claims 1 to 6, characterized in that the filler binder in the support girders (2) is chosen from the group comprising concretes based on Portland cements, on blast furnace slag cements, on Pozzolanic cements, and on high-alumina cements, high-performance concretes, resin-based concretes, and fiber concretes.
8. A bridge according to any one of claims 1 to 7, characterized in that each support girder is made of a material chosen from the group comprising general-purpose constructional steels, high yield point steels, and constructional steels having improved resistance to atmospheric corrosion.
9. A bridge according to any one of claims 1 to 8, characterized in that the support girders (2) are assembled to the cover slab (1) by pins (14) placed in openings (15) in said slab (1).
10. A bridge according to any one of claims 1 to 9, characterized in that a bearing piece (16) is placed in an opening in the cover slab (1), and is placed between the top soleplate (12) of each support girder (2) and said slab (1), said bearing piece (16) being provided with a projection (18) bearing against said top soleplate (12).
11. A bridge according to any one of claims 1 to 10, characterized in that the cover slab (1) is pre-stressed longitudinally.
12. A bridge according to any one of claims 6 to 11, characterized in that at least one of the web walls of each of the support girders (2) is made of a material different from the material of which the soleplates (12) of each of the girders is made.
13. A bridge according to any one of claims 1 to 12, characterized in that it is not provided with any spacer interconnecting the support girders below and remote from the cover slab.
14. A bridge according to any one of claims 1 to 13, characterized in that it is not provided with any bridge pieces interconnecting the support girders below the cover slab.
15. A method of making a bridge according to any one of claims 1 to 14, said method being characterized in that the support girder (2) is filled via one of the ends of said girder (2).

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