EP1065316A1 - 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 walkways 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;
• speed of execution.

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

Reference may be made, for example, 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.

Metal bridges most generally include a cover, a framework and a load-bearing system, the cover being the part of the deck that receives operating costs directly and transmits them to the carrier system, via possibly the metal framework conventionally formed by a network longitudinal (beams) and transverse (bridge parts) beams.

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

Recent roofs are generally formed by orthotropic tiles or mixed slabs or reinforced concrete slabs sometimes with a transverse prestress.

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

Orthotropic tiles have certain disadvantages.

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

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

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

Mixed slabs include a continuous sheet connected to a slab of concrete, this sheet forming the lower reinforcement of the slab. The connectors used are most often vertical studs welded to the gun connected at the head by shooting steels.

Mixed tiles have drawbacks.

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

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

The most common connectors are angles or vertical studs.

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

The invention relates more particularly to such bridges or walkways.

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

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

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

The usual range of spans for mixed bridges is from 30 to 110m approximately for continuous spans and approximately 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:

• mixed twin girders which, as their name suggests, include two beams most often connected:
  • by bridge parts for the transverse support of the slab;
  • by spacers welded perpendicularly and halfway up the beams, for relatively narrow decks;
• mixed box bridges:
  • with concrete slab resting on the walls of the box and on any transverse elements;
  • with mixed slab as presented above, with single box or multi-boxes.

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

For twin-girder composite bridges, the beams are most often with a solid core, the core and the soles being assembled by four angle weld beads.

• 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 drawbacks:

• their sensitivity to instabilities of form, by unusual deformation compared to those which can be predicted by the resistance of conventional materials. In particular, the shocks linked for example to the passage of an oversized convoy lead to plasticity in large deformations, difficult to predict by calculation. Such shocks, if they do not always lead to the ruin of the structure, cause damage which is difficult to repair without large-scale work;
• their sensitivity to fatigue, despite the strict standards in force (Eurocodes) cannot be overlooked, especially since, most often, crack initiations exist from the construction of the structure, by non-penetration of the welds angle for example.

The invention relates to a double girder composite bridge structure, in particular but not exclusively of twin-girder composite bridges with beams under the roadway, not having the drawbacks of bridges of this type known in the art prior.

In particular, the invention reveals a simple structure of a double girder composite bridge. resistant to side impact by oversized convoys for example, this structure further avoiding the use of gussets and spacers, construction of the said bridge not otherwise necessitating the stopping of traffic on the tracks crossed by the bridge.

To this end, the invention relates, according to a first aspect, to a bridge structure or of a concrete-steel gangway, comprising at least one support beam in steel of the concrete cover slab, said support beam comprising a internal cavity filled with a binder. Preferably, the support beam is completely closed except for its ends.

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

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

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

Support beams are assembled to the cover 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 projection 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 appear during the following description of embodiments, which description will be made with reference to the accompanying drawings in which:

• Figure 1 is a partial cross-sectional view of a dual-girder composite bridge structure with beams under the roadway, according to an 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, of which only half is shown in cross section in this figure 1 - the other half being symmetrical with the first half shown - includes a concrete slab 1, covering, 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 Figure 1 is defined by a first direction D1 substantially horizontal called 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 to be longitudinal.

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

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

The terms "longitudinal", "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 deck 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 longitudinal longitudinal edge of this slab and going towards the center of this, the thickness increases, reaches a maximum value plumb of each beam 2 then decreases then remains constant over a certain width of the slab.

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

In the following text, the numerical indications will refer to the sizing above, carried out for a span bridge of the order of fifteen to thirty meters to one two or three spans, commonly implemented by example for highway 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 mechanical resistance in compression at 28 days being for example greater than 80MPa.

The slab can be prestressed longitudinally, in particular when the apron is very wide. Mono strands of the order of 150KN tension useful arranged with a pitch of 30cm can for example be used, the active anchors being placed alternately on one side and the other of the slab.

In the considered embodiment, twelve SEEE 4T15S prestressing cables are provided in ducts 4.

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

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

In other embodiments, a single sidewalk is provided and / or a only one of the two sidewalks is placed above cable passages.

A bodyguard 9 is placed at the side edge of the sidewalk (s) 8. A facing 10 is secured to the longitudinal side faces of the deck.

We now describe more specifically the longitudinal beams 2 and their fixing on the cover slab 1.

Each beam 2 has a core filled with a rigid material based on a binder hydraulic 11, called "binder", or any other material having 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 clearly appear 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 the beams 2.

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

Beams can be formed by assembling two H-sections, by example HE 800A, welded together by weld beads longitudinal.

These weld beads being arranged longitudinally are not highly 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 cores 13 are pleated regularly or not.

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

In one embodiment, the webs of beams and the flanges are formed by a single steel.

In other embodiments, the cores are made of a material different from that of the soles (for example, a steel with high elastic limit for soles and general purpose structural steel for cores).

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

The presence of this internal reinforcement is optional, it is not necessary to secure the various welded parts of the beam 2. The Internal reinforcement is also not necessarily connected to beam 2.

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

We connect a binder pump by a fitting 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 flow capacity in a confined environment must be adapted as it appears to the skilled person, to ensure the desired filling of reinforced beams.

The medium being confined, it is difficult to vibrate the binder. Therefore, we use preferably self-placing 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 beam section must take this weakening into account. The invention thus solves this problem, the absence of holes also reducing the cost of manufacturing the beams.

However, filling control orifices can be made on the beams 2, these holes in no case serving to fill said beams 2, and can therefore be small.

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

Several concretes, of different types, can be used for this filling, depending for example on the distribution of the forces provided for service along the length of the beams.

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

We now refer to Figures 2 and 3.

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

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

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

A support piece forming renformis 16 or equivalent is provided in a reservation located on the underside of slab 1, in line with the sole top of each beam 2.

This support piece has a substantially horizontal lower face 17, at the exception of its central part provided with a projection 18 bearing against the upper sole of the beam 2 placed opposite.

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

A binder, not shown, poured into the reservations 15 of the slab allows assembling the beams 2 to this cover slab 1.

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

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

Although the widths of the decks achievable according to the bridge structure described above are quite high, it is no more necessary to provide for bridge parts connecting the support beams below the cover slab on which the roofing slab rests longitudinally.

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

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

It also ensures the stability of the cores 13 against the risks of spillage or to the right of the areas where are applied to the system carrying concentrated loads, such as for example the right of the supports on the mixed bridge rests.

The prefabrication of the support beams and the reduction of the operations of assembly on site not to interrupt or modify traffic on tracks crossed by the bridge or footbridge, which has an advantage important when crossing busy roads such as highways.

Claims (15)

Mixed concrete-steel bridge or walkway structure, comprising at least a steel support beam (2) of the concrete cover slab (1), said support beam (2) comprising an internal cavity filled with a binder (11), characterized in that said support beam (2) is completely closed to except for its ends. Bridge structure according to claim 1, characterized in that it comprises two beams (2) placed under the roadway (5). Bridge structure according to claim 1, characterized in that it comprises two beams (2) placed laterally above the road. Bridge structure according to any one of Claims 1 to 3, characterized in that each support beam is provided with a reinforcement internal. Bridge structure according to any one of Claims 1 to 4, characterized in that each support beam is produced by welding longitudinal of at least two elementary beams. Bridge structure according to claim 5, characterized in that each support beam (2) is produced by welding two H-shaped beams of so that the support beams have two footings (12) substantially facing each other and parallel to each other, connected by two walls core (13) substantially perpendicular to the soles (12) and facing one the other. Bridge structure according to any one of claims 1 to 6 characterized in that the filling binder for the support beams (2) is chosen among the group comprising Portland cement concretes, cements blast furnaces, pozzolanic cements, aluminous cements, high performance concrete, resin-based concrete, concrete fibers. Bridge structure according to any one of claims 1 to 7, characterized in that each support beam is made of a material chosen from the group comprising general purpose structural steels, steels with high elastic limit, resistance structural steels improved at atmospheric corrosion. Bridge structure according to any one of Claims 1 to 8, characterized in that the support beams (2) are assembled to the slab of cover (1) by studs (14) placed in reservations (15) of said slab (1). Bridge structure according to any one of Claims 1 to 9, characterized in that a support piece (16) is placed in a reservation of the cover slab (1) and is placed between the upper sole (12) of each support beam (2) and said slab (1), this support piece (16) being provided with a projection (18) bearing against said upper sole (12). Bridge structure according to any one of Claims 1 to 10, characterized in that the cover slab (1) is prestressed longitudinally. Bridge structure according to any one of Claims 6 to 11, characterized in that at least one of the core walls of the support beams (2) is made of a material different from that of the flanges (12) of these beams. Bridge structure according to any one of Claims 1 to 12, characterized in that it does not have a spacer connecting the support beams below and away from the cover slab. Bridge structure according to any one of Claims 1 to 13, characterized in that it is devoid of bridge parts connecting the beams support below the cover slab. Method for producing a bridge structure according to any one of Claims 1 to 14, characterized in that the filling of the beam support (2) is effected by one of the ends of said beam (2).

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