EP0113650B1 - Method of manufacturing a girder with a preflexed or prestressed and/or at the same time preflexed and prestressed rigid reinforcement - Google Patents

Method of manufacturing a girder with a preflexed or prestressed and/or at the same time preflexed and prestressed rigid reinforcement Download PDF

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Publication number
EP0113650B1
EP0113650B1 EP19830870126 EP83870126A EP0113650B1 EP 0113650 B1 EP0113650 B1 EP 0113650B1 EP 19830870126 EP19830870126 EP 19830870126 EP 83870126 A EP83870126 A EP 83870126A EP 0113650 B1 EP0113650 B1 EP 0113650B1
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Prior art keywords
fact
accordance
forces
elastification
loading
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EP19830870126
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German (de)
French (fr)
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EP0113650A1 (en
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Raphael Lipski
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PREFLEX SA
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PREFLEX SA
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Priority claimed from LU84506A external-priority patent/LU84506A1/en
Priority claimed from LU84535A external-priority patent/LU84535A1/en
Application filed by PREFLEX SA filed Critical PREFLEX SA
Publication of EP0113650A1 publication Critical patent/EP0113650A1/en
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    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
    • E04C3/29—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces built-up from parts of different material, i.e. composite structures
    • E04C3/293—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces built-up from parts of different material, i.e. composite structures the materials being steel and concrete
    • E04C3/294—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces built-up from parts of different material, i.e. composite structures the materials being steel and concrete of concrete combined with a girder-like structure extending laterally outside the element

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  • the present invention relates to a method for producing a pre-stressed beam, either pre-bent, or pre-bent, or both pre-bent and pre-bent, and beam consisting of at least one rigid metal frame, generally produced by rolling and / or welding which is subjected before coating to a pre-bending or a pre-shrinking, or jointly to a pre-bending and a pre-bending, to obtain a deformation in the same direction as that which it will undergo under the effect of the stresses in service, by then coating with concrete at least part of the stretched fibers of this reinforcement thus pre-bent or pre-bent, or jointly pre-bent and pre-bent at the same time, and reinforcement which, released after hardening of the concrete, cannot return to its initial form under the effect of its elasticity.
  • the present invention relates in particular to a pre-bent or pre-drawn or pre-drawn and pre-bent beam both intended for use in construction.
  • a pre-bent or pre-drawn or pre-drawn and pre-bent beam both intended for use in construction.
  • the implementation does not prevent the coating concrete applied at least on part of the tensioned fibers of the beam, from cracking under the action of subsequent stresses, during the application of the loads planned in service, and this by default of precompression.
  • the insufficient precompression of the concrete can cause during the loading of the beam, at least at the loads initially planned in service, the appearance of tensile stresses in the concrete and therefore the formation of cracks in the latter.
  • the object of the present invention is to eliminate the internal constraints of the rigid metal frame and this by a particularly economical process, before subjecting the latter to stress, according to one of the known processes and described in the aforementioned patents.
  • the method according to the invention is essentially characterized in that said metallic frame is subjected; in addition to the operations described above, in addition and beforehand, to at least one stress of elastification by means of forces determined in value and position so that the diagram of the moments or normal stresses generated is close to the envelope of all the normal moments or stresses to be reached under the loads in service, so that the internal stresses created during its manufacture are almost completely eliminated in the rigid metallic reinforcement.
  • the efforts to obtain an elastification stress may be respectively only forces substantially parallel to the longitudinal axis of the rigid metal frame or forces substantially perpendicular to the longitudinal axis of the rigid metal frame or forces both in both directions.
  • the rigid metallic reinforcement is subjected to at least one stressing of elasticity such that the stresses which it generates, added to the internal stresses already existing, reach the elastic limit in all the zones where this would have been possible under loads in service if the elastification stress (es) had not been previously applied, eliminating the internal stresses created during the manufacture of the rigid metal frame.
  • each elasticity stress is applied, optionally in several phases, to the aforementioned rigid reinforcement and the assembly which the manufacturer is obliged to use is advantageously used. to provide for carrying out said pre-shrinking or said pre-shrinking and preflexing at the same time, or the preflexing alone, in accordance with the aforementioned patents.
  • Figure 1 illustrates an embodiment of the method according to the invention, by which is applied to a metal frame (1) of a beam arranged horizontally, two vertical forces (P, and P 2 ).
  • the vertical forces (P I and P 2 ) are applied in such a way that the diagram of the moments (M 1 ) or normal stresses ( ⁇ 1 ) obtained envelops all the moments or normal stresses generated by the loads in service.
  • One proceeds in one or more phases and, with each phase, one measures the forces (P 1 and P 2 ) exerted as well as the deformation (f) which results from it.
  • the balance is then made, that is to say the difference between the initial deformation obtained during the application of the forces and the remanent deformation measured after the total relaxation of the applied forces. If this difference corresponds to the design deformation, the rigid metallic reinforcement has become virtually elastic and the desired goal is achieved. Otherwise, the loading / unloading operation must be repeated as many times as necessary, so that this difference almost corresponds to the calculation deformation. However, it is generally possible to reach the goal in a single operation.
  • the reinforcement is made sufficiently elastic, it is necessary to measure with adequate precision, either the intensity of the forces applied by means of dynamometric cells, or any other apparatus which makes it possible to measure a force and which one places in particular to the right of the applied forces and / or to the right of the supports (2), that is to say the value of the stresses, by means of extensometers which are placed at the places of maximum stresses and giving the value of the unitary elongations, from which the stresses are deduced .
  • the deformation must also be measured using devices such as a surveyor's level, a theodolite or fleximeters, so that at each loading and unloading phase, it is possible to measure the deformation corresponding.
  • FIG. 4 illustrates a second embodiment in which two equal and opposite forces, more or less parallel to its longitudinal axis, are applied to the rigid metallic reinforcement (1) of a beam arranged almost horizontally, (N 1 and N 2 ). But it could be a component of efforts inclined with respect to the longitudinal axis and, on the other hand, groups of efforts but whose results, more or less parallel to the longitudinal axis of the rigid reinforcement, will be equal and opposite.
  • forces (N, and N 2 ) are located below the center of gravity and cause traction on at least part of the cross section of the rigid metal frame (1), and forces (N, and N 2 ) which are applied in such a way that the diagram of the moments (M 2 ) or normal stresses ( ⁇ 2 ), obtained, envelops all the normal moments or stresses generated by the loads in service over at least part of the span (I) of the rigid metal frame.
  • forces (N 1 or N 2 ) are located below the center of gravity and cause traction on at least part of the cross section of the rigid metal frame (1), and forces (N, and N 2 ) which are applied in such a way that the diagram of the moments (M 2 ) or normal stresses ( ⁇ 2 ), obtained, envelops all the normal moments or stresses generated by the loads in service over at least part of the span (I) of the rigid metal frame.
  • One proceeds in one or more phases and, with each phase, one measures the forces (N 1 or N 2 ) exerted, as well as the deformation which results from
  • the reinforcement is made sufficiently elastic, it is necessary to measure with adequate precision, on the one hand the intensity of the forces applied, by means of dynamometric cells, using duly calibrated manometers, or any other apparatus which makes it possible to measure a tensile force, and to measure the value of the elongations induced by the elastification stress and measured by means of extensometers which are placed in the appropriate places, so that at each phase tensioning, then relaxation, it is possible to compare the applied forces and the corresponding deformation.
  • FIG. 5 illustrates a third embodiment in which there is applied, to the rigid metallic reinforcement (1) of a beam arranged more or less horizontally (along its longitudinal axis), in addition, as in the second embodiment, two forces (Ni, N 2 ) applied under the same conditions and possible variants, also forces (P ,, P 2 , P 3 ) vertical (perpendicular to the longitudinal axis) and set of forces (N ,, N 2 , P ,, P 2 , P 3 ) which are applied in such a way that the diagram of the moments (M 3 ) or normal stresses ( ⁇ 3 ) obtained is almost entirely the envelope of all the moments or normal stresses generated by service loads on at least part of the span (I) of the rigid metal frame.
  • one proceeds, as for the other embodiments, in one or more phases, and the overall assessment is established, of the measurements of the overall forces and of the deformations; repeating if necessary, the operation of tensioning and loading / loosening and unloading until almost complete elasticity of the rigid reinforcement.
  • any apparatus which allows a vertical force to be measured and which is placed in particular at the level of the applied vertical forces and / or the right of support.
  • it is also necessary to measure the change in the curvature of the rigid metallic reinforcement by means of measuring devices such as a level with the surveyor's, theodilot and / or fleaximeter glasses, so that at each phase of tensioning and loading, then of relaxation and discharge, it is possible to compare the forces applied and the corresponding deformation of the rigid metal frame.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Chemical & Material Sciences (AREA)
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Description

La présente invention est relative à un procédé de réalisation d'une poutre présollicitée, soit préfléchie, soit prétirée, soit à la fois prétirée et préfléchie, et poutre constituée d'au moins une armature métallique rigide, fabriquée généralement par laminage et/ou soudage que l'on soumet avant enrobage à une préflexion ou une prétraction, ou conjointement à une prétraction et une préflexion, pour obtenir une déformation dans le même sens que celle qu'elle subira sous l'effet des sollicitations en service, en enrobant ensuite de béton au moins une partie des fibres tendues de cette armature ainsi préfléchie ou prétirée, ou conjointement prétirée et préfléchie à la fois, et armature qui, relâchée après durcissement du béton, ne peut reprendre sa forme initiale sous l'effet de son élasticité.The present invention relates to a method for producing a pre-stressed beam, either pre-bent, or pre-bent, or both pre-bent and pre-bent, and beam consisting of at least one rigid metal frame, generally produced by rolling and / or welding which is subjected before coating to a pre-bending or a pre-shrinking, or jointly to a pre-bending and a pre-bending, to obtain a deformation in the same direction as that which it will undergo under the effect of the stresses in service, by then coating with concrete at least part of the stretched fibers of this reinforcement thus pre-bent or pre-bent, or jointly pre-bent and pre-bent at the same time, and reinforcement which, released after hardening of the concrete, cannot return to its initial form under the effect of its elasticity.

La présente invention concerne en particulier une poutre préfléchie ou prétirée ou prétirée et préfléchie à la fois destinée à être utilisée en construction. On connaît par les brevets belges no. 495 318, no. 501 610 et no. 509 629 des procédés permettant de réaliser une poutre à armature rigide préfléchie et par le brevet belge no. 777 891 un procédé permettant de réaliser une poutre à armature rigide pétirée ou prétirée et préfléchie à la fois.The present invention relates in particular to a pre-bent or pre-drawn or pre-drawn and pre-bent beam both intended for use in construction. We know from Belgian patents no. 495,318, no. 501 610 and no. 509 629 of the methods for producing a beam with a rigid pre-bent reinforcement and by Belgian patent no. 777 891 a method for making a beam with a rigid reinforcement that is kneaded or pre-drawn and pre-bent at the same time.

Toutefois, la mise en oeuvre, telle quelle, du procédé décrit dans lesdits brevets, ne permet pas d'éviter que le béton d'enrobage appliqué au moins sur une partie des fibres tendues de la poutre, ne se fissure sous l'action des sollicitations ultérieures, lors de l'application des charges prévues en service, et ce par défaut de précompression.However, the implementation, as it is, of the method described in the said patents, does not prevent the coating concrete applied at least on part of the tensioned fibers of the beam, from cracking under the action of subsequent stresses, during the application of the loads planned in service, and this by default of precompression.

Ce défaut de précompression résulte du fait que, dans la pratique, l'armature métallique rigide constituée éventuellement d'un profil renforcé ou composé n'est pas entièrement élastique eu égard aux contraintes internes provoquées entre autre par le laminage, le refroidissement, le dressage et/ou le soudage.This defect in precompression results from the fact that, in practice, the rigid metallic reinforcement possibly consisting of a reinforced or compound profile is not entirely elastic having regard to the internal stresses caused inter alia by rolling, cooling, dressing. and / or welding.

Cette fissuration réduit la rigidité de la poutre et, en outre, favorise la corrosion de l'acier.

  • En raison du relâchement, il n'est donc pas possible, par une simple préflexion ou prétraction ou une simple prétraction et préflexion à la fois, de tirer complètement parti de tous les avantages que la présollicitation devrait procurer, étant donné que la suppression de la sollicitation appliquée à l'armature laisse subsister une déformation rémanente à déduire de celle qui est nécessaire pour obtenir une précompression adéquate du béton.
This cracking reduces the rigidity of the beam and, moreover, promotes corrosion of the steel.
  • Due to laxity, it is therefore not possible, by a simple preflexion or pre-retraction or a simple pre-retraction and preflexion at the same time, to take full advantage of all the advantages that the pre-stress should provide, since the suppression of the stress applied to the reinforcement leaves a residual deformation to be deducted from that which is necessary to obtain adequate precompression of the concrete.

Or l'insuffisance de précompression du béton peut provoquer lors de la mise en charge de la poutre, du moins aux charges prévues initialement en service, l'apparition de contraintes de traction dans le béton et donc la formation de fissures dans celui-ci.However, the insufficient precompression of the concrete can cause during the loading of the beam, at least at the loads initially planned in service, the appearance of tensile stresses in the concrete and therefore the formation of cracks in the latter.

Le but de la présente invention est d'éliminer les contraintes internes de l'armature métallique rigide et ce par un procédé particuliérement économique, avant de soumettre cette dernière à sollicitation, selon un des procédés connus et décrit dans les brevets susmentionnés.The object of the present invention is to eliminate the internal constraints of the rigid metal frame and this by a particularly economical process, before subjecting the latter to stress, according to one of the known processes and described in the aforementioned patents.

Le procédé suivant l'invention se caractérise essentiellement en ce que l'on soumet ladite armature métallique; outre aux opérations décrites ci-dessus, en plus et préalablement, à au moins une sollicitation d'élastification au moyen d'efforts déterminés en valeur et position de telle façon que le diagramme des moments ou contraintes normales engendrés soit proche de l'enveloppe de tous les moments ou contraintes normales à atteindre sous les charges en service, de telle sorte que l'on supprime quasi totalement, dans l'armature métallique rigide, les contraintes internes nées au cours de sa fabrication.The method according to the invention is essentially characterized in that said metallic frame is subjected; in addition to the operations described above, in addition and beforehand, to at least one stress of elastification by means of forces determined in value and position so that the diagram of the moments or normal stresses generated is close to the envelope of all the normal moments or stresses to be reached under the loads in service, so that the internal stresses created during its manufacture are almost completely eliminated in the rigid metallic reinforcement.

Comme on peut prévoir de soumettre l'armature métallique rigide uniquement à une prétraction ou une préflexion ou encore à la fois à une prétraction en une préflexion, les efforts pour obtenir une sollicitation d'élastification pourront être respectivement uniquement des efforts sensiblement parallèles à l'axe longitudinal de l'armature métallique rigide ou des efforts sensiblement perpendiculaires à l'axe longitudinal de l'armature métallique rigide ou encore des efforts à la fois dans les deux directions.As it can be envisaged to subject the rigid metallic reinforcement only to a pre-shrinking or a preflexion or even at the same time to a pre-shrinking in a pre-deflection, the efforts to obtain an elastification stress may be respectively only forces substantially parallel to the longitudinal axis of the rigid metal frame or forces substantially perpendicular to the longitudinal axis of the rigid metal frame or forces both in both directions.

Suivant une particularité de l'invention, on soumet l'armature métallique rigide à au moins une sollicitation d'élastification telle que les contraintes qu'elle engendre, ajoutées aux contraintes internes déjà existantes, atteignent la limite d'élasticité dans toutes les zones où cela aurait été possible sous charges en service si l'on n'avait pas applquépréalablement la (les) sollicitation(s) d'élastification supprimant les contraintes internes nées au cours de la fabrication de l'armature métallique rigide.According to a feature of the invention, the rigid metallic reinforcement is subjected to at least one stressing of elasticity such that the stresses which it generates, added to the internal stresses already existing, reach the elastic limit in all the zones where this would have been possible under loads in service if the elastification stress (es) had not been previously applied, eliminating the internal stresses created during the manufacture of the rigid metal frame.

Dans un mode de réalisation particulier, on applique, éventuellement en plusieurs phases, chaque sollicitation d'élastification à l'armature rigide susdite et l'on utilise avantageusement le montage que le fabricant est de toute façon obligé . de prévoir pour réaliser ladite prétraction ou lesdites prétraction et préflexion à la fois, ou la préflexion seule, conformément aux brevets susmentionnés.In a particular embodiment, each elasticity stress is applied, optionally in several phases, to the aforementioned rigid reinforcement and the assembly which the manufacturer is obliged to use is advantageously used. to provide for carrying out said pre-shrinking or said pre-shrinking and preflexing at the same time, or the preflexing alone, in accordance with the aforementioned patents.

D'autres particularités et détails de l'invention ressortiront de la description suivant les dessins annexés au présent mémoire.Other features and details of the invention will emerge from the description following the drawings appended to this memo.

Dans ces dessins:

  • - la figure 1 représente schématiquement un mode de réalisation de l'invention, dans lequel on soumet un profilé, constituant l'armature d'une poutre, à une sollicitation préalable d'élastification, au moyen d'efforts verticaux extérieurs P;
  • - la figure 2 est une coupe transversale suivant la ligne 11-11 de l'armature métallique rigide montrée aux figures 1, 4 et 5;
  • - la figure 3 montre le diagramme des moments ou contraintes normales engendrés dans l'armature métallique rigide par les efforts verticaux extérieurs P;
  • - la figure 4 représente schématiquement un autre mode de réalisation conforme à l'invention, dans lequel on soumet un profilé, constituant l'armature d'une poutre, à une sollicitation préalable d'élastification, au moyen d'efforts extérieurs N, et N2 horizontaux, ainsi que le diagramme des moments ou contraintes normales engendrés dans l'armature métallique rigide, par les efforts horizontaux appliqués;
  • - la figure 5 représente encore un autre mode de réalisation conforme à J'invention, dans lequel on soumet un profilé, constituant l'armature rigide d'une poutre, à une sollicitation préalable d'élastification, au moyen d'efforts extérieurs à la fois verticaux P et horizontaux N, ainsi que le diagramme des moments ou contraintes normales engendrés dans l'armature métallique rigide, par les efforts extérieurs P et N.
In these drawings:
  • - Figure 1 schematically shows an embodiment of the invention, in which a section, constituting the frame of a beam, is subjected to a prior elastification stress, by means of external vertical forces P;
  • - Figure 2 is a cross section along line 11-11 of the rigid metal frame shown in Figures 1, 4 and 5;
  • - Figure 3 shows the diagram of the normal moments or stresses generated in the rigid metal frame by the external vertical forces P;
  • FIG. 4 schematically represents another embodiment in accordance with the invention, in which a section, constituting the reinforcement of a beam, is subjected to a prior elastification stress, by means of external forces N, and N 2 horizontal, as well as the diagram of the moments or normal stresses generated in the rigid metallic reinforcement, by the horizontal forces applied;
  • FIG. 5 represents yet another embodiment in accordance with the invention, in which a profile, constituting the rigid frame of a beam, is subjected to a prior elastification stress, by means of forces external to the vertical times P and horizontal N, as well as the diagram of the normal moments or stresses generated in the rigid metallic reinforcement, by the external forces P and N.

La figure 1 illustre un mode de réalisation du procédé suivant l'invention, par lequel on applique, sur une armature métallique (1 ) d'une poutre disposée horizontalement, deux efforts verticaux (P, et P2).Figure 1 illustrates an embodiment of the method according to the invention, by which is applied to a metal frame (1) of a beam arranged horizontally, two vertical forces (P, and P 2 ).

Les efforts verticaux (PI et P2) sont appliqués de telle façon que le diagramme des moments (M1) ou contraintes normales (δ1) obtenu enveloppe tous les moments ou contraintes normales engendrés par les charges en service.The vertical forces (P I and P 2 ) are applied in such a way that the diagram of the moments (M 1 ) or normal stresses (δ 1 ) obtained envelops all the moments or normal stresses generated by the loads in service.

On procède en une ou plusieurs phases et, à chaque phase, on mesure les efforts (P1 et P2) exercés ainsi que la déformation (f) qui en résulte.One proceeds in one or more phases and, with each phase, one measures the forces (P 1 and P 2 ) exerted as well as the deformation (f) which results from it.

Après avoir atteint les efforts nominaux et prévus au calcul, on les maintient le temps nécessaire pour que les molécules de l'acier se mettent définitivement en place.After having reached the nominal forces and provided for in the calculation, they are maintained for the time necessary for the molecules of the steel to be put in place definitively.

Ce temps écoulé, on réduit les efforts appliqués pour atteindre la valeur zéro. A la décharge, on mesure également tant les efforts que les déformations.Once this time has elapsed, the forces applied to reach the value zero are reduced. At the discharge, both the forces and the deformations are also measured.

On fait ensuite le bilan, c'est-à-dire la différence entre la déformation initiale obtenue lors de l'application des efforts et la déformation rémanente mesurée après le relâchement total des efforts appliqués. Si cette différence correspond à la déformation de calcul, l'armature métallique rigide est devenue virtuellement élastique et le but recherché est atteint. Dans le cas contraire, il faut répéter l'opération de mise en charge/dé- charge, autant de fois qu'il sera nécessaire, pour que cette différence corresponde quasiment à la déformation de calcul. Cependant, il est généralement possible d'atteindre le but en une seule opération.The balance is then made, that is to say the difference between the initial deformation obtained during the application of the forces and the remanent deformation measured after the total relaxation of the applied forces. If this difference corresponds to the design deformation, the rigid metallic reinforcement has become virtually elastic and the desired goal is achieved. Otherwise, the loading / unloading operation must be repeated as many times as necessary, so that this difference almost corresponds to the calculation deformation. However, it is generally possible to reach the goal in a single operation.

Pour être certain que l'armature est rendue suffisamment élastique, on doit mesurer avec une précision adéquate, soit l'intensité des forces appliquées au moyen de cellules dynamométriques, ou tout autre appareillage qui permet de mesurer un effort et que l'on place notamment au droit des efforts appliqués et/ou au droit des appuis (2), soit la valeur des contraintes, au moyen d'extensomètres que l'on place aux endroits de contraintes maximales et donnant la valeur des allongements unitaires, dont on déduit les contraintes.To be certain that the reinforcement is made sufficiently elastic, it is necessary to measure with adequate precision, either the intensity of the forces applied by means of dynamometric cells, or any other apparatus which makes it possible to measure a force and which one places in particular to the right of the applied forces and / or to the right of the supports (2), that is to say the value of the stresses, by means of extensometers which are placed at the places of maximum stresses and giving the value of the unitary elongations, from which the stresses are deduced .

On doit également mesurer la déformation au moyen d'appareils tels qu'un niveau à lunette de géomètre, un théodolite ou des fleximètres, de telle sorte qu'à chaque phase de mise en charge, puis décharge, il soit possible de mesurer la déformation correspondante.The deformation must also be measured using devices such as a surveyor's level, a theodolite or fleximeters, so that at each loading and unloading phase, it is possible to measure the deformation corresponding.

La figure 4 illustre un deuxième mode de réalisation dans lequel on applique, à l'armature métallique rigide (1) d'une poutre disposée quasi horizontalement, deux efforts égaux et opposés, plus ou moins parallèles à son axe longitudinal, (N1 et N2). Mais il pourrait s'agir d'une composante d'efforts inclinés par rapport à l'axe longitudinal et, d'autre part, de groupes d'efforts mais dont les résultantes, plus ou moins parallèles à l'axe longitudinal de l'armature rigide, seront égales et opposées.FIG. 4 illustrates a second embodiment in which two equal and opposite forces, more or less parallel to its longitudinal axis, are applied to the rigid metallic reinforcement (1) of a beam arranged almost horizontally, (N 1 and N 2 ). But it could be a component of efforts inclined with respect to the longitudinal axis and, on the other hand, groups of efforts but whose results, more or less parallel to the longitudinal axis of the rigid reinforcement, will be equal and opposite.

Ces efforts (N, et N2) sont situés en dessous du centre de gravité et provoquent une traction sur au moins une partie de la section transversale de l'armature métallique rigide (1), et efforts (N, et N2) qui sont appliqués de telle façon que le diagramme des moments (M2) ou contraintes normales (δ2), obtenu enveloppe tous les moments ou contraintes normales engendrés par les charges en service sur au moins une partie de la portée (I) de l'armature métallique rigide. On procède en une ou plusieurs phases et, à chaque phase, on mesure les efforts (N1 ou N2) exercés, ainsi que la déformation qui en résulte.These forces (N, and N 2 ) are located below the center of gravity and cause traction on at least part of the cross section of the rigid metal frame (1), and forces (N, and N 2 ) which are applied in such a way that the diagram of the moments (M 2 ) or normal stresses (δ 2 ), obtained, envelops all the normal moments or stresses generated by the loads in service over at least part of the span (I) of the rigid metal frame. One proceeds in one or more phases and, with each phase, one measures the forces (N 1 or N 2 ) exerted, as well as the deformation which results from it.

Après avoir atteint les efforts nominaux prévus au calcul, on les maintient le temps nécessaire pour que les molécules de l'acier se mettent définitivement en place.After having reached the nominal forces provided for in the calculation, they are maintained for the time necessary for the molecules of the steel to be put in place definitively.

Ce temps écoulé, on réduit les efforts appliqués pour atteindre la valeur zéro. En relâchant la traction, on mesure également tant les efforts que les déformations.Once this time has elapsed, the forces applied to reach the value zero are reduced. By releasing the traction, one also measures both the forces and the deformations.

On fait ensuite le bilan, comme indiqué ci- avant.We then take stock, as indicated above.

Pour être certain que l'armature est rendue suffisamment élastique, on doit mesurer avec une précision adéquate, d'une part l'intensité des forces appliquées, au moyen de cellules dynamométriques, à l'aide de manomètres dûment tarés, ou encore tout autre appareillage qui permet de mesurer un effort de traction, et d'ature part la valeur des allongements induits par la sollicitation d'élastification et mesurés au moyen d'extensomètres que l'on place aux endroits adéquats, de telle sorte qu'à chaque phase de mise en traction, puis relâchement, il soit possible de confronter les efforts appliqués et la déformation correspondante.To be certain that the reinforcement is made sufficiently elastic, it is necessary to measure with adequate precision, on the one hand the intensity of the forces applied, by means of dynamometric cells, using duly calibrated manometers, or any other apparatus which makes it possible to measure a tensile force, and to measure the value of the elongations induced by the elastification stress and measured by means of extensometers which are placed in the appropriate places, so that at each phase tensioning, then relaxation, it is possible to compare the applied forces and the corresponding deformation.

La figure 5 illustre un troisième mode de réalisation dans lequel on applique, à l'armature métallique rigide (1) d'une poutre disposée plus ou moins horizontalement (selon son axe longitudinal), outre, comme dans le second mode de réalisation, deux efforts (Ni, N2) appliqués dans les mêmes conditions et variantes possibles, également des efforts (P,, P2, P3) verticaux (perpendiculaires à l'axe longitudinal) et ensemble d'efforts (N,, N2, P,, P2, P3) qui sont appliqués de telle façon que le diagramme des moments (M3) ou contraintes normales (δ3) obtenu soit quasi entièrement l'enveloppe de tous les moments ou contraintes normales engendrés par les charges en service sur au moins une partie de la portée (I) de l'armature métallique rigide.FIG. 5 illustrates a third embodiment in which there is applied, to the rigid metallic reinforcement (1) of a beam arranged more or less horizontally (along its longitudinal axis), in addition, as in the second embodiment, two forces (Ni, N 2 ) applied under the same conditions and possible variants, also forces (P ,, P 2 , P 3 ) vertical (perpendicular to the longitudinal axis) and set of forces (N ,, N 2 , P ,, P 2 , P 3 ) which are applied in such a way that the diagram of the moments (M 3 ) or normal stresses (δ 3 ) obtained is almost entirely the envelope of all the moments or normal stresses generated by service loads on at least part of the span (I) of the rigid metal frame.

Par ailleurs, on procède, de même que pour les autres modes de réalisation, en une ou plusieurs phases, et l'on établit le bilan global, des mesures des efforts globaux et des déformations; on répète si nécessaire, l'opération de mise en traction et en charge/relâchement et décharge jusqu'à élastification quasi complète de l'armature rigide.In addition, one proceeds, as for the other embodiments, in one or more phases, and the overall assessment is established, of the measurements of the overall forces and of the deformations; repeating if necessary, the operation of tensioning and loading / loosening and unloading until almost complete elasticity of the rigid reinforcement.

Pour mesurer les efforts verticaux (P,, P2, P3) et horizontaux (N,, N2) on utilise tout appareillage qui permet de mesurer un effort vertical et que l'on place notamment au droit des efforts verticaux appliqués et/ou au droit des appuis. On doit également, dans ce mode de réalisation, mesurer la modification de la courbure de l'armature métallique rigide au moyen d'appareils de mesure tels qu'un niveau à lunette de géomètre, théodilote et/ou fléximètres, de telle sorte qu'a chaque phase de mise en tension et en charge, puis de relâchement et décharge, il soit possible de confronter les efforts appliqués et la déformation correspondante de l'armature métallique rigide.To measure the vertical (P ,, P 2 , P 3 ) and horizontal (N ,, N 2 ) forces, any apparatus is used which allows a vertical force to be measured and which is placed in particular at the level of the applied vertical forces and / or the right of support. In this embodiment, it is also necessary to measure the change in the curvature of the rigid metallic reinforcement by means of measuring devices such as a level with the surveyor's, theodilot and / or fleaximeter glasses, so that at each phase of tensioning and loading, then of relaxation and discharge, it is possible to compare the forces applied and the corresponding deformation of the rigid metal frame.

Il est évident que la présente invention n'est pas limitée aux formes de réalisation décrites ci-dessus mais l'étendue de la protection est déterminée ou la teneur des revendications et l'on ne sortirait pas de ce cadre en appliquant la ou les résultantes des efforts ou groupes d'efforts horizontaux ou sensiblement horizontaux, à deux ou plusieurs armatures métalliques rigides, par exemple, reliées entre elles et dans le prolongement les unes des autres.It is obvious that the present invention is not limited to the embodiments described above but the scope of protection is determined or the content of the claims and it would not go beyond this scope by applying the result (s) horizontal or substantially horizontal efforts or groups of efforts, with two or more rigid metallic reinforcements, for example, interconnected and in the extension of one another.

Claims (14)

1. Process for the production of a prestressed beam, either pre-flexed or pre-drawn, or both pre-drawn and pre-flexed, and the beam made up of at least one rigid metal truss, usually made by rolling and/or welding which has been subjected before coating to pre-flexing or pre-traction, or to a combination of pre-traction and pre-flexing to achieve deformation in the same sense as that it would be submitted to by the action of the service loads, then coating with concrete at least one part of the tensioned fibers of such truss thus pre-flexed or pre-drawn, or both pre-drawn and pre-flexed, and the truss which, when released after the concrete has set, cannot resume its original shape under the action of its elasticity, characterized by the fact that, previously, the rigid metal truss is in addition subjected to at least one elastification loading by means of forces determined as to value and position in such a way that the diagram of moments or normal stresses generated is close to the envelope of all moments and normal stresses to be reached under service loads, in such a way that the internal stresses in the rigid metal truss arising in the course of its manufacture are almost entirely eliminated.
2. Process in accordance with claim 1, characterized by the fact that the forces used to obtain an elastification loading of the rigid metal truss are two horizontal forces or groups of forces, parallel or inclined along its longitudinal axis, of which the resultants are equal and opposite.
3. Process in accordance with any one of the claims 1 and 2, characterized by the fact that the forces used to obtain an elastification loading of the rigid truss are only or in addition one or more practically perpendicular forces in relation to its longitudinal axis.
4. Process in accordance with any one of the claims 1 to 3, characterized by the fact that the rigid metal truss is subjected to at least one elastification loading such that the stresses which it generates, when added to the already existing internal stresses, reach the limit of elasticity in all areas where this could be possible under service loads if the elastification loading(s) had not been previously applied, almost eliminating the internal stresses arising in the course of manufacture of the rigid metal truss.
5. Process in accordance with any one of the claims 1 to 4, characterized by the fact that the elastification loading)s) is/are maintained on the rigid metal truss for such time as is necessary to ensure that the deformations occasioned through exceeding the elastic limit can develop almost completely.
6. Process in accordance with any one of the claims 1 to 5, characterized by the fact that each elastification loading is applied to the above- mentioned rigid truss possibly in several stages.
7. Process in accordance with any one of the claims 3 to 6, characterized by the fact that the elastification loading is successively applied and released until the moment when the residual deflection (Δf) due to it becomes insignificant.
8. Process in accordance with any one of the claims 1 to 7, characterized by the fact that the assembly which the manufacturer is obliged in any case to provide is used to effect the said pre-flexing or the said pre-traction and/or the said pre-traction and the said pre-flexing at the same time.
9. Process in accordance with any one of the claims 2 and 4 to 8, characterized by the fact that the intensity of applied horizontal forces is measured with adequate precision by means of dynamometric cells, duly calibrated manometers or alternatively by any other equipment capable of measuring a tensile force.
10. Process in accordance with any one of the claims 3 to 8, characterized by the fact that the deformation of the rigid metal truss due to the elastification loading is measured by the change in its curvature.
11. Process in accordance with any one of the claims 1 to 10, characterized by the fact that the value of the elongation induced by the elastification loading is measured by strain gauges placed in appropriate positions.
12. Process in accordance with any one of the claims 3 to 11, characterized by the fact that the intensity of the vertical forces constituting the elastification loading is measured with adequate precision with dynamometric cells which .are placed more especially where such forces act and/ or at the supports.
13. Process in accordance with any one of the claims 3 to 12, characterized by the fact that the deformations of the rigid metal truss are measured by means of measuring instruments such as surveyor's level, theodolite and/or flex- imeter.
14. Beam manufactured by the process described in accordance with any one of the claims 1 to 13.
EP19830870126 1982-12-03 1983-12-02 Method of manufacturing a girder with a preflexed or prestressed and/or at the same time preflexed and prestressed rigid reinforcement Expired EP0113650B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
LU84506A LU84506A1 (en) 1982-12-03 1982-12-03 Prefab. steel beam embedded in concrete - is repeatedly preloaded for bending and stress to eliminate residual stresses
LU84506 1982-12-03
LU84535A LU84535A1 (en) 1982-12-16 1982-12-16 Prefab. steel beam embedded in concrete - is repeatedly preloaded for bending and stress to eliminate residual stresses
LU84535 1982-12-16

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EP0113650A1 EP0113650A1 (en) 1984-07-18
EP0113650B1 true EP0113650B1 (en) 1986-04-09

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EP19830870126 Expired EP0113650B1 (en) 1982-12-03 1983-12-02 Method of manufacturing a girder with a preflexed or prestressed and/or at the same time preflexed and prestressed rigid reinforcement

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DE (1) DE3362958D1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE904131A (en) * 1986-01-29 1986-05-15 Entpr S Sbbm Et Six Construct PROCESS FOR PRODUCING BEAMS COMPRISING STEEL AND CONCRETE BEAMS AND BEAMS OBTAINED ACCORDING TO THIS PROCESS.
FR2670517B1 (en) * 1990-12-13 1993-04-09 Normandie Const Meca CROSSING ELEMENT FOR THE CROSSING OF OBSTACLES.

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Publication number Priority date Publication date Assignee Title
BE495318A (en) *
BE777891A (en) * 1972-01-10 1972-05-02 Lipski Raphael PRE-TIRED RIGID REINFORCEMENT BEAM.

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DE3362958D1 (en) 1986-05-15
EP0113650A1 (en) 1984-07-18

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