WO2018069560A1 - Method for active reinforcement against shear stress or shear failure in structural load-bearing elements and active reinforcement system - Google Patents

Method for active reinforcement against shear stress or shear failure in structural load-bearing elements and active reinforcement system Download PDF

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Publication number
WO2018069560A1
WO2018069560A1 PCT/ES2017/070675 ES2017070675W WO2018069560A1 WO 2018069560 A1 WO2018069560 A1 WO 2018069560A1 ES 2017070675 W ES2017070675 W ES 2017070675W WO 2018069560 A1 WO2018069560 A1 WO 2018069560A1
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WO
WIPO (PCT)
Prior art keywords
reinforcement
bearing element
reinforcement element
structural bearing
linear reinforcement
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Application number
PCT/ES2017/070675
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Spanish (es)
French (fr)
Inventor
Antoni Cladera Bohigas
Carlos Rodrigo Ribas González
Benito Mas Gracia
Juan Maria Rius Gibert
Luis Alberto MONTOYA CORONADO
Joaquín Guillermo RUIZ PINILLA
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Universitat De Les Illes Balears
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Publication of WO2018069560A1 publication Critical patent/WO2018069560A1/en

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G23/00—Working measures on existing buildings
    • E04G23/02—Repairing, e.g. filling cracks; Restoring; Altering; Enlarging
    • E04G23/0218—Increasing or restoring the load-bearing capacity of building construction elements
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
    • E04G21/12—Mounting of reinforcing inserts; Prestressing
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G23/00—Working measures on existing buildings
    • E04G23/02—Repairing, e.g. filling cracks; Restoring; Altering; Enlarging
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G23/00—Working measures on existing buildings
    • E04G23/02—Repairing, e.g. filling cracks; Restoring; Altering; Enlarging
    • E04G23/0218—Increasing or restoring the load-bearing capacity of building construction elements
    • E04G23/0225—Increasing or restoring the load-bearing capacity of building construction elements of circular building elements, e.g. by circular bracing

Definitions

  • the present invention belongs to the technical field of construction, specifically to structural elements and their reinforcement against the efforts to repair and control cracks, and more specifically to reinforcements against shear stress for structural supporting elements such as beams and pillars, and against punching effort in slab type elements.
  • the invention relates in particular to a method of active reinforcement at shear stress or punching capable of generating fissures in structural supporting elements, such as beams, pillars and slabs, in which at least one linear reinforcement element is anchored, such as a bar, wire, strip or similar element, of alloy with memory in a pre-stretched form in martensitic phase, partial or total, around the structural bearing element to be reinforced, said anchor being made by overlapping at least two sections of the linear reinforcement element itself . Subsequently, it is activated by heating causing the transformation of the bar, wire, strapping or similar reinforcement element of partial or total martensitic phase, to austenitic phase, and the tensions caused close the fissure and increase the shear resistance in the bearing element of structures
  • the invention further relates to an active reinforcement system with at least one linear reinforcement element such as a bar, wire, strip or similar element, of shape memory alloy.
  • the supporting elements of the structures are requested against different types of stresses, such as bending, axial and cutting moment. These efforts produce tensions inside the structural element, which, once the tensile strength of the material is matched, produces cracks.
  • Fissures near the support and that are inclined, in the case of concrete structures, are mainly due to shear stress or punching.
  • shear cracks are they propagate in general parallel to the guideline of the piece due to the orthotropic character of the wood.
  • These fissures may appear due to a poor dimensioning of the element, an increase in loads in the structure or the loss of its resistant capacity due to degradation, and given the fragility of shear breakage in this type of elements and the type of danger that entails, it is often necessary to reinforce the structural element once a fissure due to shear stress has appeared, or in advance of its appearance if such a possibility is foreseen.
  • the shear reinforcement of a structural element is also desirable in the event that the structure may be subject to accidental actions, such as earthquakes or explosions, not foreseen or underestimated in the original design and construction of the structure.
  • shear reinforcements can be classified into two types: passive reinforcements and active reinforcements.
  • Passive reinforcements consist of the provision of plates, bars or sheets of different types of materials, such as steel or carbon fiber laminates, among others, by adhesion or by mechanical anchors that "sew" existing or foreseeable cracks of so that by increasing external solicitations, the passive reinforcement provided resists, in whole or in part, the increase in shear stress.
  • This type of reinforcements only goes into action for increased stresses from its disposition, and for its correct operation it is necessary, in general, that the reinforced structure increases its deformation and its level of damage (reinforcement activated by the expansion of the original material of the structure to be reinforced). Therefore, to avoid excessive deformations after reinforcement, initial deformations are limited to the maximum when arranging the reinforcement. To this end, these types of reinforcements usually require an attachment or previous download of the original structure.
  • the active reinforcements consist instead of the arrangement of plates, bars or sheets that "sew" the cracks, as in the previous case, but to which a tension of tension (tested) is applied before their anchorage, generally of mechanical type but that could be adhesion.
  • this type of reinforcements consists of two parts: prestressed elements and anchoring elements, where the testing process is always mechanical.
  • the testing process requires hydraulic jacks and wedges, or reinforcements screwed with wrenches that control the tightening torque.
  • the present invention solves the problems existing in the state of the art by means of an active reinforcement method against shear stress or punching in structural bearing elements.
  • These structural supporting elements are mainly of the type of beams, pillars and slabs.
  • the method has an arrangement stage of at least one linear reinforcement element made of a shape memory alloy (SMA), pre-stretched in partial or total martensitic phase, around the bearing element of structures to be reinforced
  • this linear reinforcement element may consist of a bar, wire, strap or similar element, but the main feature is that it is linear, that is, with one of its dimensions clearly predominant over the others.
  • the arrangement is made in such a way that the reinforcing bar, wire or strap is arranged transversely to the generated fissure, or with the possibility of being generated by the shear force or punching.
  • an anchor of the bar, wire, strap or similar reinforcement element is made around the structural bearing element.
  • this anchoring is carried out by overlapping at least two sections of the linear reinforcement element itself, that is, an anchoring of the self-anchored type in all or at least one area of the reinforcement element, thus avoiding damage. the structural element with perforations in that area, and also avoiding the use of resins or adhesives.
  • subsequent actions are avoided in that area to improve the durability of the union of the reinforcement element to the structural bearing element.
  • the activation of the bar, wire, strap or similar reinforcement element is carried out by heating it, causing the transformation of said reinforcement bar from martensitic phase to austenitic phase, it is say the reverse martensitic transformation.
  • the bar, wire, strapping or similar reinforcing element By heating the bar, wire, strapping or similar reinforcing element, it is attempted to shorten, and the shortening is prevented by the structural bearing element to which it wraps, thus transmitting stresses that compress the entire structural bearing element, and in particular to the fissure generated by the shear stress.
  • a prestressing effect of confinement in the structural bearing element is produced, the previous crack is closed and the shear resistance is increased, significantly increasing the ductility of the structure before shear breakage.
  • the present invention has the advantages that it does not need a mechanical testing process (unlike the active reinforcements of the prior art), since it uses the shape memory effect of SMA alloys, and also does not require accumulation of damage of the structure to reinforce to start its work (unlike passive reinforcements of the state of the art), since the reinforcement is not based on the expansion of the material to be reinforced.
  • the method object of the present invention can also be applied to floor slabs, jácenas and different supports.
  • the arrangement of the bar, wire, strapping or similar reinforcing element is carried out in a substantially helical continuous manner around the structural bearing element.
  • sections of the bar, wire, strapping or similar reinforcement element are arranged perpendicular to the guideline of the structure bearing element, and other sections are arranged inclined with respect to the element guideline structural bearing
  • the anchoring of the bar, wire, strap or similar reinforcement element around the structural bearing element can be carried out by means of overlapping connected of two sections at one of the ends of the bar itself, wire, strap or similar reinforcement element, while the other section is fixed to the structural bearing element.
  • the anchoring of the bar, wire, strapping or similar reinforcement element around the structural bearing element can be carried out by means of an overlap connected of two sections at the two ends of the bar itself, wire, strapping or similar reinforcement element.
  • the arrangement of the bar, wire or similar reinforcing element is carried out discreetly by means of at least one bar, wire, strapping or similar reinforcing element, which may be arranged in "U” or at "O" around the structural bearing element.
  • the anchoring of the reinforcing element around the structural bearing element is carried out by fixing the bar, wire, strapping or similar reinforcing element to the structural bearing element.
  • the anchoring is carried out in an auto-anchored manner, by overlapping the initial and final sections of the bar, wire, strapping or similar element, or by means of at least one auxiliary plate and corresponding bolts or nuts for fixing, although it is possible Perform by alternative means.
  • the anchoring of these around the structural bearing element is carried out by joining the sections that overlap each other by means of a buckle and the testing and bending said sections by means of a strap tensioner supported by said buckle. Subsequently, the final anchoring can be carried out by means of nails, screws or rivets, in the latter case self-tensioned without drilling the supporting structure to be reinforced.
  • the heating of the bar, wire, strapping or similar reinforcement element to obtain its activation can be carried out by different means such as hot air gun, blowtorch, thermal blankets or passage of electricity along the bar, wire, strap or similar reinforcement element.
  • a step prior to the arrangement of the bar, wire, strapping or similar reinforcement element around the bearing element of structures, consisting of a rounding of the edges of said structural bearing element can be performed .
  • the method presents an additional stage of coating the bar, wire, strapping or similar reinforcement element after its activation, by means of projected material, mortar, plasterboard, or combination of all of them, for its protection against fire or different adverse environmental conditions.
  • the protection against fire is increased by the fact of not necessarily having to use resins or adhesives, which was common in the prior systems of the state of the art of reinforcement by polymer reinforced fibers.
  • Another object of the present invention is an active reinforcement system against shear stress or punching in structural bearing elements.
  • This system has at least one linear reinforcement element made of alloy with memory in a martensitic phase, partial or total, which is anchored around the structural bearing element, for fixing to it.
  • this element Linear reinforcement can consist of a bar, wire, strap or similar element, but the essential characteristic is that it is a linear reinforcement element, that is, with one of its dimensions clearly predominant over the rest.
  • the shape memory alloy of the system object of the present invention has a crystalline structure in a martensitic phase, partial or total, at room temperature, and must have a final transformation temperature of martensitic to austenitic phase between 100 and C and 250 e C, this temperature can vary depending on the alloy used. In addition, its initial temperature of direct transformation from austenitic phase to martensitic phase must be below the working ambient temperature of the structural element.
  • the shape memory alloy will consist of Ni-Ti-Nb or Fe-Mn-Si, with the possibility of having other components in a smaller proportion, although it may be made of other materials that meet the requirements indicated above.
  • Figure 1 shows schematically a structural bearing element, specifically a beam, which has a fissure generated by shear stress.
  • Figure 2 is a schematic view of the beam of Figure 1 with an active reinforcement system object of the present invention in which the linear reinforcement element is disposed around said beam in a continuous helical manner.
  • Figure 3 is a schematic view of a particular embodiment of the reinforcement anchor shown in Figure 2 to the beam.
  • Figure 4 is a schematic view of a reinforcement system with arrangement of bar, wire, strap or similar reinforcement element in a continuous helical manner in an alternative structural bearing element.
  • Figure 5 shows the structural bearing element of Figure 4 with a reinforcement system with alternative arrangement of several "U” rebar in a discrete manner.
  • Figure 6 shows the structural bearing element of Figures 4 and 5 with a reinforcement system with discrete arrangement of several reinforcement strips arranged at "0".
  • Figure 7 shows a particular embodiment in which the reinforcement is performed by means of straps joined by a buckle on which a test has been carried out and folded by means of a strap tensioner supported on said buckle.
  • Figures 8 to 10 show alternative methods of arrangement of the reinforcement system around another structural bearing element, in this case a vertical column.
  • Figures 1 1 and 12 show different examples of possible reinforcement bar anchors around the bearing element.
  • Figure 13 is a schematic view of a particular embodiment of the reinforcement system in a structural bearing element type slab.
  • Figure 14 is a comparative graph showing a schematic example of a load curve applied against deformation under load application point of a non-reinforced structural bearing element, reinforced without activation and by the method object of the present invention of reinforced structure and activated.
  • Linear reinforcement element such as bar, wire, strapping or similar, alloy with shape memory
  • the object of the present invention is an active reinforcement method against shear stress or punching in structural bearing elements.
  • the structural supporting elements 1 to be reinforced can be of the type of beams, pillars and slabs.
  • Figure 1 schematically shows a structural bearing element 1, specifically a beam, which has a fissure 2 generated by the shear force.
  • Said structural bearing element 1, with or without fissure 2 is the one that will be reinforced with the method object of the present invention.
  • the method object of the present invention has an arrangement stage of at least one linear alloy reinforcement element 3 with memory prestressed in a martensitic phase, partial or total, around the structural bearing element 1 to be reinforced, in which said bar, wire, strap or similar element of reinforcement 3 is disposed transversely to the fissure 2 that is generated or can be generated due to shear stress or punching.
  • this linear reinforcement element 3 can consist of a bar, wire, strap or similar element, but the essential characteristic is that it is a linear reinforcement element, that is, with a clearly predominant dimension over the rest.
  • an anchor of the bar, wire, strap or similar reinforcement element 3 is made around the structural bearing element 1, by overlapping at least two sections of the linear reinforcement element 3 itself, that is, an anchoring of the self-anchored type in all or in at least one area of the reinforcement element 3. This prevents damage to the structural element 1 with perforations in that area, and the use of resins or adhesives for bonding the reinforcement to the structural bearing element 1 is also avoided.
  • an activation of the bar, wire, strap or similar reinforcement element 3 is carried out by heating it, causing the transformation of the bar, wire, strap or similar reinforcement element 3 from martensitic phase to austenitic phase.
  • the arrangement of the bar, wire, strapping or similar reinforcement element 3 is carried out in a substantially helical continuous manner around the structural bearing element 1, as seen in Figures 2, 3 , 4 and 8.
  • sections of the bar, wire, strap or similar reinforcement element 3 are arranged perpendicular to the guideline of the structural bearing element 1 and other sections of the bar, wire, strap or similar element of reinforcement 3 are arranged inclined with respect to the guideline of the structural bearing element 1, being transverse to the fissure 2 and "sewing" it.
  • the inclined sections are observed with respect to the guideline of the structural bearing element 1, while the sections perpendicular to it are hidden in said figures.
  • the anchoring of the bar, strapping, wire or similar reinforcing element 3 is arranged at the beginning and at the end thereof, and can be performed by connected overlap of two sections at one of the ends of the bar, wire, strapping or similar reinforcement element 3, while the other section is fixed to the structural bearing element 1.
  • the anchoring of the bar, wire, strapping or similar reinforcement element 3 around the structural bearing element 1 can be carried out by means of a connected overlap of two sections in both ends of the bar, wire, strapping or similar reinforcement element 3.
  • this can be done by usual auxiliary devices such as sleeves, nuts, U-bolts or clamps.
  • the anchoring of the reinforcement element 3 is carried out by fixing it to the element structural bearing 1.
  • this anchoring is carried out in an auto-anchored manner, by overlapping the initial and final sections of the bar, wire, strapping or similar reinforcement element 3, or by at least one auxiliary plate 4 and the corresponding nuts or bolts 5 for anchoring, although alternative means could be used.
  • the anchors may be bolted and should be designed to always withstand the maximum possible force on the bar, wire, strap or similar reinforcement element 3.
  • the anchoring of these around the structural bearing element 1 is carried out by joining the sections that overlap each other by means of a buckle 6 and the testing and bending of said sections by means of a strapping tensioner supported by said buckle 6. Subsequently, the final anchoring can be carried out by means of nails, screws or rivets, in the latter case self-tensioned without piercing the supporting structure 1 to be reinforced.
  • the activation of the bar, wire, strapping or similar reinforcement element 3 by heating it can be achieved by different means such as hot air gun, torch, thermal blankets, or the passage of electricity along said bar, wire strap or similar reinforcement element 3, thanks to Joule's law.
  • a particular embodiment of the invention incorporates an additional step of coating the bars, wires, strips or similar reinforcement elements 3 after activation, by different means such as projected material, mortar, plasterboard and combinations thereof.
  • This coating can be done to protect the reinforcement system against fire or different adverse environmental conditions.
  • the surface of the structural bearing element 1 to be reinforced must initially be treated to increase its roughness. This will be possible through the use of hydrojet, sandblasting, or repeated by manual or mechanical methods, before arranging the bar, wire or similar reinforcement element 3.
  • the method may include a previous stage of realization of grooves or rubs in the structural supporting element 1 for the arrangement of the bars, wires or similar reinforcement elements 3 in said grooves, and the subsequent coating thereof by means indicated above. The grooves will be made using a brush or similar means.
  • the protection against fire is further increased by the fact of not necessarily having to use resins or adhesives, which was common in the previous systems of the state of the reinforcement technique by polymer reinforced fibers.
  • the method object of the present invention can also be applied for reinforcements to punching in slabs or abacus of reticular slabs, similar to that applied to beams, taking into account that in the case of punching in slabs or abacus of reticular slabs the reinforcements are they will have in two directions of the space from the pillar, as shown in figure 13. Said reinforcements will require several previous perforations in the slab to be able to arrange the bar, wire, strap or similar reinforcement element 3 that surrounds the element structural bearing Note that in the areas to be reinforced around an inner pillar, these reinforcements are arranged at least four times (two directions from the pillar in two directions).
  • the process of arranging the bar, wire, strapping or similar reinforcement element 3 is the same as indicated above, adding the previous step of drilling the slab for the subsequent arrangement of the reinforcement. It is also possible the use of the bar, wire, strap or similar reinforcement element 3 in "U” in this case. The method is also valid for beams, joists or ribs of slabs with a "T" cross section.
  • Another object of the present invention is an active reinforcement system against shear stress or punching in structural bearing elements.
  • the system has at least one linear reinforcement element 3 made of alloy with memory of partial or total martensitic phase shape, anchorable around the structural bearing element 1.
  • this linear reinforcement element 3 may consist of a bar, strap, wire or similar element, but the essential characteristic is that it is a linear reinforcement element, that is, with a clearly predominant dimension over the rest.
  • this shape memory alloy has characteristics necessary to carry out the reinforcement optimally, such as that it has a crystalline structure in partial or total martensitic phase at room temperature, which has a final martensitic phase transformation temperature.
  • a austenitic located between 100 and C and 250 and C, this temperature can vary depending on the alloy used, and has an initial temperature of direct transformation from austenitic phase to martensitic phase below the ambient working temperature of the structural bearing element 1, preferably at temperatures below -50 C and for not performing said direct transformation into working conditions.
  • the shape memory alloy is such that it generates a recovery strain under deformation prevented in the transformation of martensitic to austenitic phase of at least 200 MPa.
  • the shape memory alloy can be Ni-Ti-Nb, or Fe-Mn-Si, with the possible incorporation of other components in a smaller proportion, although it could be any memory alloy in a way that meets the indicated requirements previously.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Mechanical Engineering (AREA)
  • Civil Engineering (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Reinforcement Elements For Buildings (AREA)

Abstract

Method for active reinforcement against shear stress or shear failure in structural load-bearing elements such as beams, pillars and slabs in which is provided at least one bar, wire, strip or similar reinforcement element (3) in a shape-memory alloy pre-stretched in the martensite phase around the structural load-bearing element (1), crosswise to a fissure (2) that is generated or which may be generated by the shear force or shear failure. The reinforcement element (3) is subsequently anchored around the structural load-bearing element (1), such anchoring being achieved by overlapping at least two sections of the linear reinforcement element itself. Subsequently the reinforcement element (3) is activated by heating, causing its transformation from the martensite phase to the austenite phase. In addition, the invention relates to a system for active reinforcement with at least one similar reinforcement element (3) in shape-memory alloy.

Description

MÉTODO DE REFUERZO ACTIVO FRENTE A ESFUERZO CORTANTE O PUNZONAMIENTO EN ELEMENTOS PORTANTES ESTRUCTURALES. Y SISTEMA  METHOD OF ACTIVE REINFORCEMENT AGAINST CUTTING EFFORT OR PUNCHING IN STRUCTURAL SUPPORTING ELEMENTS. AND SYSTEM
DE REFUERZO ACTIVO DESCRIPCIÓN  ACTIVE REINFORCEMENT DESCRIPTION
Campo de la invención Field of the Invention
La presente invención pertenece al campo técnico de la construcción, concretamente a los elementos estructurales y su refuerzo frente a los esfuerzos soportados para reparar y controlar fisuras, y más concretamente a los refuerzos frente a esfuerzo cortante para elementos portantes estructurales tales como vigas y pilares, y frente a esfuerzo de punzonamiento en elementos tipo losa.  The present invention belongs to the technical field of construction, specifically to structural elements and their reinforcement against the efforts to repair and control cracks, and more specifically to reinforcements against shear stress for structural supporting elements such as beams and pillars, and against punching effort in slab type elements.
La invención se refiere en particular a un método de refuerzo activo a esfuerzo cortante o punzonamiento capaces de generar fisuras en elementos portantes estructurales, tales como vigas, pilares y losas, en el que se ancla al menos un elemento de refuerzo lineal, tal como una barra, alambre, fleje o elemento similar, de aleación con memoria de forma pre-estirada en fase martensítica, parcial o total, alrededor del elemento portante estructural a reforzar, realizándose dicho anclaje mediante solape de al menos dos tramos del propio elemento de refuerzo lineal. Posteriormente se activa mediante calentamiento originando la transformación de la barra, alambre, fleje o elemento similar de refuerzo de fase martensítica parcial o total, a fase austenítica, y las tensiones provocadas cierran la fisura y aumentan la resistencia a esfuerzo cortante en el elemento portante de estructuras.  The invention relates in particular to a method of active reinforcement at shear stress or punching capable of generating fissures in structural supporting elements, such as beams, pillars and slabs, in which at least one linear reinforcement element is anchored, such as a bar, wire, strip or similar element, of alloy with memory in a pre-stretched form in martensitic phase, partial or total, around the structural bearing element to be reinforced, said anchor being made by overlapping at least two sections of the linear reinforcement element itself . Subsequently, it is activated by heating causing the transformation of the bar, wire, strapping or similar reinforcement element of partial or total martensitic phase, to austenitic phase, and the tensions caused close the fissure and increase the shear resistance in the bearing element of structures
La invención se refiere adicionalmente a un sistema de refuerzo activo con al menos un elemento de refuerzo lineal tal como una barra, alambre, fleje o elemento similar, de aleación con memoria de forma.  The invention further relates to an active reinforcement system with at least one linear reinforcement element such as a bar, wire, strip or similar element, of shape memory alloy.
Antecedentes de la invención Background of the invention
Los elementos portantes de las estructuras se encuentran solicitados frente a distintos tipos de esfuerzos, tales como momento flector, axial y cortante. Dichos esfuerzos producen tensiones en el interior del elemento estructural, las cuales, una vez igualada la resistencia a tracción del material, producen fisuras.  The supporting elements of the structures are requested against different types of stresses, such as bending, axial and cutting moment. These efforts produce tensions inside the structural element, which, once the tensile strength of the material is matched, produces cracks.
Las fisuras cercanas al apoyo y que se encuentran inclinadas, en el caso de estructuras de hormigón, son debidas principalmente al esfuerzo cortante o punzonamiento. En el caso de estructuras de madera, las fisuras a cortante se propagan en general paralelamente a la directriz de la pieza debido al carácter ortótropo de la madera. Estas fisuras pueden aparecer por un mal dimensionado del elemento, por un aumento de cargas en la estructura o por la pérdida de la capacidad resistente de la misma por la degradación, y dada la fragilidad de la rotura a cortante en este tipo de elementos y el tipo de peligro que conlleva, es frecuentemente necesario el refuerzo del elemento estructural una vez ha aparecido una fisura debida a esfuerzo cortante, o con antelación a su aparición si se prevé dicha posibilidad. También es deseable el refuerzo a cortante de un elemento estructural en el caso de que la estructura pueda estar sometida a acciones accidentales, como por ejemplo sismo o explosiones, no previstas o subestimadas en el proyecto y construcción original de la estructura. Fissures near the support and that are inclined, in the case of concrete structures, are mainly due to shear stress or punching. In the case of wooden structures, shear cracks are they propagate in general parallel to the guideline of the piece due to the orthotropic character of the wood. These fissures may appear due to a poor dimensioning of the element, an increase in loads in the structure or the loss of its resistant capacity due to degradation, and given the fragility of shear breakage in this type of elements and the type of danger that entails, it is often necessary to reinforce the structural element once a fissure due to shear stress has appeared, or in advance of its appearance if such a possibility is foreseen. The shear reinforcement of a structural element is also desirable in the event that the structure may be subject to accidental actions, such as earthquakes or explosions, not foreseen or underestimated in the original design and construction of the structure.
Actualmente los refuerzos a cortante se pueden clasificar en dos tipos: refuerzos pasivos y refuerzos activos.  Currently shear reinforcements can be classified into two types: passive reinforcements and active reinforcements.
Los refuerzos pasivos consisten en la disposición de placas, barras o láminas de diferentes tipos de materiales, tales como acero o laminados de fibras de carbono, entre otros, por adherencia o mediante anclajes mecánicos que "cosen" las fisuras, existentes o previsibles, de forma que al aumentar las solicitaciones externas el refuerzo pasivo dispuesto resista total o parcialmente el incremento de esfuerzo cortante. Este tipo de refuerzos sólo entra en acción para incrementos de esfuerzos a partir de su disposición, y para su correcto funcionamiento es necesario, en general, que la estructura reforzada aumente su deformación y su nivel de daño (refuerzo activado por la dilatancia del material original de la estructura a reforzar). Por ello, para evitar deformaciones excesivas después del refuerzo, se limitan al máximo las deformaciones iniciales a la hora de disponer el refuerzo. Con este fin, este tipo de refuerzos suelen requerir de un apeo o descargue previo de la estructura original.  Passive reinforcements consist of the provision of plates, bars or sheets of different types of materials, such as steel or carbon fiber laminates, among others, by adhesion or by mechanical anchors that "sew" existing or foreseeable cracks of so that by increasing external solicitations, the passive reinforcement provided resists, in whole or in part, the increase in shear stress. This type of reinforcements only goes into action for increased stresses from its disposition, and for its correct operation it is necessary, in general, that the reinforced structure increases its deformation and its level of damage (reinforcement activated by the expansion of the original material of the structure to be reinforced). Therefore, to avoid excessive deformations after reinforcement, initial deformations are limited to the maximum when arranging the reinforcement. To this end, these types of reinforcements usually require an attachment or previous download of the original structure.
Los refuerzos activos consisten en cambio en la disposición de placas, barras o láminas que "cosen" las fisuras, como en el caso anterior, pero a las que se aplica una tensión de tracción (tesado) antes de su anclaje, generalmente de tipo mecánico pero que podría ser por adherencia. Por lo general este tipo de refuerzos consta de dos partes: elementos pretensados y elementos de anclaje, en donde el proceso de tesado es siempre mecánico. En este tipo de refuerzos el proceso de tesado requiere de gatos hidráulicos y cuñas, o de refuerzos atornillados con llaves que controlen el par de apriete. Para poder llevar a cabo el tesado, es necesario por tanto espacio de trabajo alrededor de todo el elemento estructural, para dar cabida a los elementos auxiliares. Este último requerimiento no es siempre posible o deseable a la hora de reforzar un elemento estructural de estas características, además de que para trazados que no son rectos, y especialmente los que presentan fuertes curvaturas, la transmisión mecánica del pretensado resulta prácticamente imposible. The active reinforcements consist instead of the arrangement of plates, bars or sheets that "sew" the cracks, as in the previous case, but to which a tension of tension (tested) is applied before their anchorage, generally of mechanical type but that could be adhesion. In general this type of reinforcements consists of two parts: prestressed elements and anchoring elements, where the testing process is always mechanical. In this type of reinforcements the testing process requires hydraulic jacks and wedges, or reinforcements screwed with wrenches that control the tightening torque. In order to carry out the testing, it is therefore necessary work space around the entire structural element, to accommodate the auxiliary elements. This last requirement is not always possible or desirable at the time of reinforce a structural element of these characteristics, in addition to that for paths that are not straight, and especially those that have strong curvatures, the mechanical transmission of the prestressing is practically impossible.
Era por tanto deseable un método y un sistema de refuerzo activo frente a esfuerzo cortante o punzonamiento en elementos portantes estructurales, evitando los inconvenientes existentes en los anteriores métodos de refuerzo frente a esfuerzos cortantes del estado de la técnica.  It was therefore desirable a method and an active reinforcement system against shear stress or punching in structural bearing elements, avoiding the inconveniences existing in the previous reinforcement methods against shear stresses of the prior art.
Descripción de la invención Description of the invention
La presente invención resuelve los problemas existentes en el estado de la técnica mediante un método de refuerzo activo frente a esfuerzo cortante o punzonamiento en elementos portantes estructurales. Estos elementos portantes estructurales son principalmente del tipo de vigas, pilares y losas.  The present invention solves the problems existing in the state of the art by means of an active reinforcement method against shear stress or punching in structural bearing elements. These structural supporting elements are mainly of the type of beams, pillars and slabs.
El método tiene una etapa de disposición de al menos un elemento de refuerzo lineal realizada en una aleación con memoria de forma (SMA por sus siglas en inglés, "Shape memory alloy') pre-estirada en fase martensítica, parcial o total, alrededor del elemento portante de estructuras a reforzar. Particularmente este elemento de refuerzo lineal puede consistir en una barra, alambre, fleje o elemento similar, pero la característica principal es que sea lineal, es decir, con una de sus dimensiones claramente predominante sobre las otras. Esta disposición se realiza de forma tal que la barra, alambre o fleje de refuerzo queda dispuesta transversalmente a la fisura generada, o con posibilidad de ser generada por el esfuerzo cortante o punzonamiento.  The method has an arrangement stage of at least one linear reinforcement element made of a shape memory alloy (SMA), pre-stretched in partial or total martensitic phase, around the bearing element of structures to be reinforced Particularly this linear reinforcement element may consist of a bar, wire, strap or similar element, but the main feature is that it is linear, that is, with one of its dimensions clearly predominant over the others. The arrangement is made in such a way that the reinforcing bar, wire or strap is arranged transversely to the generated fissure, or with the possibility of being generated by the shear force or punching.
A continuación, se realiza un anclaje de la barra, alambre, fleje o elemento similar de refuerzo alrededor del elemento portante estructural. De acuerdo con la presente invención este anclaje se realiza mediante solape de al menos dos tramos del propio elemento de refuerzo lineal, es decir, un anclaje de tipo autoanclado en todas o en al menos una zona del elemento de refuerzo, evitándose de esta forma dañar el elemento estructural con perforaciones en esa zona, y evitando también el uso de resinas o adhesivos. Además se evitan actuaciones posteriores en esa zona para la mejora de la durabilidad de la unión del elemento de refuerzo al elemento portante estructural.  Next, an anchor of the bar, wire, strap or similar reinforcement element is made around the structural bearing element. In accordance with the present invention, this anchoring is carried out by overlapping at least two sections of the linear reinforcement element itself, that is, an anchoring of the self-anchored type in all or at least one area of the reinforcement element, thus avoiding damage. the structural element with perforations in that area, and also avoiding the use of resins or adhesives. In addition, subsequent actions are avoided in that area to improve the durability of the union of the reinforcement element to the structural bearing element.
Posteriormente se lleva a cabo la activación de la barra, alambre, fleje o elemento similar de refuerzo mediante calentamiento de ésta, originando la transformación de dicha barra de refuerzo de fase martensítica a fase austenítica, es decir la transformación martensítica inversa. Mediante el calentamiento de la barra, alambre, fleje o elemento similar de refuerzo, ésta se intenta acortar, y el acortamiento está impedido por el elemento portante estructural al que envuelve, transmitiendo así tensiones que comprimen todo el elemento portante estructural, y en particular a la fisura generada por el esfuerzo cortante. Así se produce un efecto de pretensado postesado de confinamiento en el elemento portante estructural, cerrándose la fisura previa y se aumenta la resistencia a esfuerzo cortante, aumentando significativamente la ductilidad de la estructura ante la rotura por cortante. Subsequently, the activation of the bar, wire, strap or similar reinforcement element is carried out by heating it, causing the transformation of said reinforcement bar from martensitic phase to austenitic phase, it is say the reverse martensitic transformation. By heating the bar, wire, strapping or similar reinforcing element, it is attempted to shorten, and the shortening is prevented by the structural bearing element to which it wraps, thus transmitting stresses that compress the entire structural bearing element, and in particular to the fissure generated by the shear stress. Thus, a prestressing effect of confinement in the structural bearing element is produced, the previous crack is closed and the shear resistance is increased, significantly increasing the ductility of the structure before shear breakage.
La presente invención presenta las ventajas de que no necesita un proceso de tesado mecánico (al contrario que los refuerzos activos del estado de la técnica), ya que utiliza el efecto de memoria de forma de las aleaciones SMA, y además no precisa de la acumulación de daño de la estructura a reforzar para iniciar su trabajo (al contrario que los refuerzos pasivos del estado de la técnica), ya que el refuerzo no está basado en la dilatancia del material a reforzar.  The present invention has the advantages that it does not need a mechanical testing process (unlike the active reinforcements of the prior art), since it uses the shape memory effect of SMA alloys, and also does not require accumulation of damage of the structure to reinforce to start its work (unlike passive reinforcements of the state of the art), since the reinforcement is not based on the expansion of the material to be reinforced.
El método objeto de la presente invención se puede aplicar también a forjados, jácenas y diferentes soportes.  The method object of the present invention can also be applied to floor slabs, jácenas and different supports.
Según una realización particular de la invención, la disposición de la barra, alambre, fleje o elemento similar de refuerzo se realiza de forma sustancialmente helicoidal continua alrededor del elemento portante estructural. De acuerdo con esta disposición, de forma preferente unos tramos de la barra, alambre, fleje o elemento similar de refuerzo quedan dispuestos en disposición perpendicular a la directriz del elemento portante de estructuras, y otros tramos quedan dispuestos inclinados con respecto a la directriz del elemento portante estructural.  According to a particular embodiment of the invention, the arrangement of the bar, wire, strapping or similar reinforcing element is carried out in a substantially helical continuous manner around the structural bearing element. According to this arrangement, preferably sections of the bar, wire, strapping or similar reinforcement element are arranged perpendicular to the guideline of the structure bearing element, and other sections are arranged inclined with respect to the element guideline structural bearing
De acuerdo con esta realización particular, el anclaje de la barra, alambre, fleje o elemento similar de refuerzo alrededor del elemento portante estructural se puede llevar a cabo mediante solape conectado de dos tramos en uno de los extremos de la propia barra, alambre, fleje o elemento similar de refuerzo, mientras que el otro tramo se fija al elemento portante estructural. Alternativamente, el anclaje de la barra, alambre, fleje o elemento similar de refuerzo alrededor del elemento portante estructural se puede realizar mediante solape conectado de dos tramos en los dos extremos de la propia barra, alambre, fleje o elemento similar de refuerzo.  In accordance with this particular embodiment, the anchoring of the bar, wire, strap or similar reinforcement element around the structural bearing element can be carried out by means of overlapping connected of two sections at one of the ends of the bar itself, wire, strap or similar reinforcement element, while the other section is fixed to the structural bearing element. Alternatively, the anchoring of the bar, wire, strapping or similar reinforcement element around the structural bearing element can be carried out by means of an overlap connected of two sections at the two ends of the bar itself, wire, strapping or similar reinforcement element.
Según una realización particular alternativa de la invención, la disposición de la barra, alambre o elemento similar de refuerzo se realiza de forma discreta mediante al menos una barra, alambre, fleje o elemento similar de refuerzo, que puede estar dispuesta en "U" o en "O" alrededor del elemento portante estructural. De acuerdo con esta disposición, de forma particular el anclaje del elemento de refuerzo alrededor del elemento portante estructural se realiza fijando la barra, alambre, fleje o elemento similar de refuerzo al elemento portante estructural. Preferentemente, el anclaje se realiza de forma autoanclada, conectando por solape los tramos iniciales y finales de la propia barra, alambre, fleje o elemento similar, o mediante al menos una placa auxiliar y correspondientes pernos o tuercas para realizar la fijación, aunque se puede realizar mediante medios alternativos. According to a particular alternative embodiment of the invention, the arrangement of the bar, wire or similar reinforcing element is carried out discreetly by means of at least one bar, wire, strapping or similar reinforcing element, which may be arranged in "U" or at "O" around the structural bearing element. In accordance with This arrangement, in particular the anchoring of the reinforcing element around the structural bearing element is carried out by fixing the bar, wire, strapping or similar reinforcing element to the structural bearing element. Preferably, the anchoring is carried out in an auto-anchored manner, by overlapping the initial and final sections of the bar, wire, strapping or similar element, or by means of at least one auxiliary plate and corresponding bolts or nuts for fixing, although it is possible Perform by alternative means.
De acuerdo con una realización particular de la invención, en el caso en que los elementos de refuerzo sean flejes, el anclaje de éstos alrededor del elemento portante estructural se realiza mediante la unión de los tramos que se solapan entre sí mediante una hebilla y el tesado y doblado de dichos tramos mediante una tensadora de flejes soportada por dicha hebilla. Posteriormente se puede realizar el anclaje definitivo mediante clavos, tornillos o remaches, en este último caso de forma autotensada sin perforar la estructura portante a reforzar.  According to a particular embodiment of the invention, in the case where the reinforcement elements are strapping, the anchoring of these around the structural bearing element is carried out by joining the sections that overlap each other by means of a buckle and the testing and bending said sections by means of a strap tensioner supported by said buckle. Subsequently, the final anchoring can be carried out by means of nails, screws or rivets, in the latter case self-tensioned without drilling the supporting structure to be reinforced.
De forma particular, el calentamiento de la barra, alambre, fleje o elemento similar de refuerzo para obtener la activación de ésta se puede realizar mediante diferentes medios tales como pistola de aire caliente, soplete, mantas térmicas o paso de electricidad a lo largo de la barra, alambre, fleje o elemento similar de refuerzo.  In particular, the heating of the bar, wire, strapping or similar reinforcement element to obtain its activation can be carried out by different means such as hot air gun, blowtorch, thermal blankets or passage of electricity along the bar, wire, strap or similar reinforcement element.
Preferentemente, en el método objeto de la presente invención se puede realizar un paso previo a la disposición de la barra, alambre, fleje o elemento similar de refuerzo alrededor del elemento portante de estructuras, consistente en un redondeo de los cantos de dicho elemento portante estructural.  Preferably, in the method object of the present invention, a step prior to the arrangement of the bar, wire, strapping or similar reinforcement element around the bearing element of structures, consisting of a rounding of the edges of said structural bearing element can be performed .
Y también de forma preferente, el método presenta una etapa adicional de recubrimiento de la barra, alambre, fleje o elemento similar de refuerzo tras su activación, por medio de material proyectado, mortero, placas de yeso, o combinación de todos ellos, para su protección frente a fuego o diferentes condiciones ambientales adversas. La protección frente al fuego se ve incrementada por el hecho de no tener que utilizar necesariamente resinas o adhesivos, lo cual era habitual en los sistemas anteriores del estado de la técnica de refuerzo mediante fibras reforzadas de polímeros.  And also preferably, the method presents an additional stage of coating the bar, wire, strapping or similar reinforcement element after its activation, by means of projected material, mortar, plasterboard, or combination of all of them, for its protection against fire or different adverse environmental conditions. The protection against fire is increased by the fact of not necessarily having to use resins or adhesives, which was common in the prior systems of the state of the art of reinforcement by polymer reinforced fibers.
Otro objeto de la presente invención es un sistema de refuerzo activo frente a esfuerzo cortante o punzonamiento en elementos portantes estructurales. Este sistema tiene al menos un elemento de refuerzo lineal realizado en aleación con memoria de forma en fase martensítica, parcial o total, el cual es anclado alrededor del elemento portante estructural, para su fijación a éste. Particularmente este elemento de refuerzo lineal puede consistir en una barra, alambre, fleje o elemento similar, pero la característica esencial es que es un elemento de refuerzo lineal, es decir, con una de sus dimensiones claramente predominante sobre el resto. Another object of the present invention is an active reinforcement system against shear stress or punching in structural bearing elements. This system has at least one linear reinforcement element made of alloy with memory in a martensitic phase, partial or total, which is anchored around the structural bearing element, for fixing to it. Particularly this element Linear reinforcement can consist of a bar, wire, strap or similar element, but the essential characteristic is that it is a linear reinforcement element, that is, with one of its dimensions clearly predominant over the rest.
De forma preferente, la aleación con memoria de forma del sistema objeto de la presente invención tiene estructura cristalina en fase martensítica, parcial o total, a temperatura ambiente, y debe presentar una temperatura final de transformación de fase martensítica a austenítica situada entre 100eC y 250eC, pudiendo variar esta temperatura en función de la aleación utilizada. Además, su temperatura inicial de transformación directa de fase austenítica a fase martensítica deberá estar por debajo de la temperatura ambiente de trabajo del elemento estructural. Preferentemente la aleación con memoria de forma consistirá en Ni-Ti-Nb o Fe-Mn-Si, con la posibilidad de contar con otros componentes en menor proporción, aunque puede estar realizada en otros materiales que cumplan los requisitos anteriormente indicados. Breve descripción de los dibujos Preferably, the shape memory alloy of the system object of the present invention has a crystalline structure in a martensitic phase, partial or total, at room temperature, and must have a final transformation temperature of martensitic to austenitic phase between 100 and C and 250 e C, this temperature can vary depending on the alloy used. In addition, its initial temperature of direct transformation from austenitic phase to martensitic phase must be below the working ambient temperature of the structural element. Preferably, the shape memory alloy will consist of Ni-Ti-Nb or Fe-Mn-Si, with the possibility of having other components in a smaller proportion, although it may be made of other materials that meet the requirements indicated above. Brief description of the drawings
A continuación, para facilitar la comprensión de la invención, a modo ilustrativo pero no limitativo se describirá una realización de la invención que hace referencia a una serie de figuras.  Next, to facilitate the understanding of the invention, an illustrative but non-limiting way will describe an embodiment of the invention that refers to a series of figures.
La figura 1 muestra de forma esquemática un elemento portante estructural, concretamente una viga, que presenta una fisura generada por esfuerzo cortante.  Figure 1 shows schematically a structural bearing element, specifically a beam, which has a fissure generated by shear stress.
La figura 2 es una vista esquemática de la viga de la figura 1 con un sistema de refuerzo activo objeto de la presente invención en el que el elemento de refuerzo lineal se dispone alrededor de dicha viga de forma helicoidal continua.  Figure 2 is a schematic view of the beam of Figure 1 with an active reinforcement system object of the present invention in which the linear reinforcement element is disposed around said beam in a continuous helical manner.
La figura 3 es una vista esquemática de una realización particular del anclaje del refuerzo mostrado en la figura 2 a la viga.  Figure 3 is a schematic view of a particular embodiment of the reinforcement anchor shown in Figure 2 to the beam.
La figura 4 es una vista esquemática de un sistema de refuerzo con disposición de barra, alambre, fleje o elemento similar de refuerzo de forma helicoidal continua en un elemento portante estructural alternativo.  Figure 4 is a schematic view of a reinforcement system with arrangement of bar, wire, strap or similar reinforcement element in a continuous helical manner in an alternative structural bearing element.
La figura 5 muestra el elemento portante estructural de la figura 4 con un sistema de refuerzo con disposición alternativa de varias barras de refuerzo en "U" de forma discreta.  Figure 5 shows the structural bearing element of Figure 4 with a reinforcement system with alternative arrangement of several "U" rebar in a discrete manner.
La figura 6 muestra el elemento portante estructural de las figuras 4 y 5 con un sistema de refuerzo con disposición discreta de varios flejes de refuerzo dispuestos en "0".  Figure 6 shows the structural bearing element of Figures 4 and 5 with a reinforcement system with discrete arrangement of several reinforcement strips arranged at "0".
La figura 7 muestra una realización particular en la que el refuerzo se realiza mediante flejes unidos mediante una hebilla sobre los que se ha realizado un tesado y doblado mediante una tensadora de flejes soportada en dicha hebilla. Figure 7 shows a particular embodiment in which the reinforcement is performed by means of straps joined by a buckle on which a test has been carried out and folded by means of a strap tensioner supported on said buckle.
Las figuras 8 a 10 muestran métodos alternativos de disposición del sistema de refuerzo alrededor de otro elemento portante estructural, en este caso una columna vertical.  Figures 8 to 10 show alternative methods of arrangement of the reinforcement system around another structural bearing element, in this case a vertical column.
Las figuras 1 1 y 12 muestran diferentes ejemplos de posibles anclajes de la barra de refuerzo alrededor del elemento portante.  Figures 1 1 and 12 show different examples of possible reinforcement bar anchors around the bearing element.
La figura 13 es una vista esquemática de una realización particular del sistema de refuerzo en un elemento portante estructural tipo losa.  Figure 13 is a schematic view of a particular embodiment of the reinforcement system in a structural bearing element type slab.
La figura 14 es una gráfica comparativa que muestra un ejemplo esquemático de curva de carga aplicada frente a deformación bajo punto de aplicación de la carga de un elemento portante estructural no reforzado, reforzado sin activación y mediante el método objeto de la presente invención de estructura reforzada y activada.  Figure 14 is a comparative graph showing a schematic example of a load curve applied against deformation under load application point of a non-reinforced structural bearing element, reinforced without activation and by the method object of the present invention of reinforced structure and activated.
En estas figuras se hace referencia a un conjunto de elementos que son: In these figures reference is made to a set of elements that are:
1 . elementos portantes estructurales one . structural bearing elements
2. fisura  2. fissure
3. elemento de refuerzo lineal tal como barra, alambre, fleje o elemento similar, de aleación con memoria de forma  3. Linear reinforcement element such as bar, wire, strapping or similar, alloy with shape memory
4. placa auxiliar  4. auxiliary plate
5. elementos de fijación auxiliares, tuercas, pernos, tornillos, clavos remaches 6. hebilla 5. auxiliary fasteners, nuts, bolts, screws, nails rivets 6. buckle
Descripción detallada de la invención Detailed description of the invention
El objeto de la presente invención es un método de refuerzo activo frente a esfuerzo cortante o punzonamiento en elementos portantes estructurales.  The object of the present invention is an active reinforcement method against shear stress or punching in structural bearing elements.
Tal y como se puede apreciar en las figuras, los elementos portantes estructurales 1 a reforzar pueden ser del tipo de vigas, pilares y losas.  As can be seen in the figures, the structural supporting elements 1 to be reinforced can be of the type of beams, pillars and slabs.
La figura 1 muestra de forma esquemática un elemento portante estructural 1 , concretamente una viga, que presenta una fisura 2 generada por el esfuerzo cortante. Dicho elemento portante estructural 1 , con la fisura 2 o sin ella, es el que se reforzará con el método objeto de la presente invención.  Figure 1 schematically shows a structural bearing element 1, specifically a beam, which has a fissure 2 generated by the shear force. Said structural bearing element 1, with or without fissure 2, is the one that will be reinforced with the method object of the present invention.
El método objeto de la presente invención tiene una etapa de disposición de al menos un elemento de refuerzo lineal 3 de aleación con memoria de forma pre- estirada en fase martensítica, parcial o total, alrededor del elemento portante estructural 1 a reforzar, en la que dicha barra, alambre, fleje o elemento similar de refuerzo 3 queda dispuesta transversalmente a la fisura 2 que se genera o se puede generar debido al esfuerzo cortante o punzonamiento. Particularmente este elemento de refuerzo lineal 3 puede consistir en una barra, alambre, fleje o elemento similar, pero la característica esencial es que es un elemento de refuerzo lineal, es decir, con una dimensión claramente predominante sobre el resto. The method object of the present invention has an arrangement stage of at least one linear alloy reinforcement element 3 with memory prestressed in a martensitic phase, partial or total, around the structural bearing element 1 to be reinforced, in which said bar, wire, strap or similar element of reinforcement 3 is disposed transversely to the fissure 2 that is generated or can be generated due to shear stress or punching. Particularly this linear reinforcement element 3 can consist of a bar, wire, strap or similar element, but the essential characteristic is that it is a linear reinforcement element, that is, with a clearly predominant dimension over the rest.
Posteriormente se realiza un anclaje de la barra, alambre, fleje o elemento similar de refuerzo 3 alrededor del elemento portante estructural 1 , mediante el solape de al menos dos tramos del propio elemento de refuerzo lineal 3, es decir, un anclaje de tipo autoanclado en todas o en al menos una zona del elemento de refuerzo 3. De esta forma se evita dañar el elemento estructural 1 con perforaciones en esa zona, y también se evita el uso de resinas o adhesivos para el pegado del refuerzo al elemento portante estructural 1 . Finalmente se realiza una activación de la barra, alambre, fleje o elemento similar de refuerzo 3 mediante calentamiento de ésta, originando la transformación de la barra, alambre, fleje o elemento similar de refuerzo 3 de fase martensítica a fase austenítica.  Subsequently, an anchor of the bar, wire, strap or similar reinforcement element 3 is made around the structural bearing element 1, by overlapping at least two sections of the linear reinforcement element 3 itself, that is, an anchoring of the self-anchored type in all or in at least one area of the reinforcement element 3. This prevents damage to the structural element 1 with perforations in that area, and the use of resins or adhesives for bonding the reinforcement to the structural bearing element 1 is also avoided. Finally, an activation of the bar, wire, strap or similar reinforcement element 3 is carried out by heating it, causing the transformation of the bar, wire, strap or similar reinforcement element 3 from martensitic phase to austenitic phase.
De acuerdo con diferentes realizaciones particulares de la invención, la disposición de la barra, alambre, fleje o elemento similar de refuerzo 3 se realiza de forma sustancialmente helicoidal continua alrededor del elemento portante estructural 1 , tal y como se observa en las figuras 2, 3, 4 y 8.  According to different particular embodiments of the invention, the arrangement of the bar, wire, strapping or similar reinforcement element 3 is carried out in a substantially helical continuous manner around the structural bearing element 1, as seen in Figures 2, 3 , 4 and 8.
Según la realización particular anterior, de forma preferente unos tramos de la barra, alambre, fleje o elemento similar de refuerzo 3 quedan dispuestos en disposición perpendicular a la directriz del elemento portante estructural 1 y otros tramos de la barra, alambre, fleje o elemento similar de refuerzo 3 quedan dispuestos inclinados con respecto a la directriz del elemento portante estructural 1 , quedando transversales a la fisura 2 y "cosiendo" ésta. En las figuras 2-3 se observan los tramos inclinados con respecto a la directriz del elemento portante estructural 1 , mientras que los tramos perpendiculares a éste quedan ocultos en dichas figuras.  According to the previous particular embodiment, preferably sections of the bar, wire, strap or similar reinforcement element 3 are arranged perpendicular to the guideline of the structural bearing element 1 and other sections of the bar, wire, strap or similar element of reinforcement 3 are arranged inclined with respect to the guideline of the structural bearing element 1, being transverse to the fissure 2 and "sewing" it. In figures 2-3 the inclined sections are observed with respect to the guideline of the structural bearing element 1, while the sections perpendicular to it are hidden in said figures.
De acuerdo con esta realización según la disposición helicoidal continua alrededor del elemento portante estructural 1 , el anclaje de la barra, fleje, alambre o elemento similar de refuerzo 3 se dispone al principio y al final de la misma, y se puede realizar mediante solape conectado de dos tramos en uno de los extremos de la propia barra, alambre, fleje o elemento similar de refuerzo 3, mientras que el otro trmo se fija al elemento portante estructural 1 . Alternativamente, el anclaje de la barra, alambre, fleje o elemento similar de refuerzo 3 alrededor del elemento portante estructural 1 se puede realizar mediante solape conectado de dos tramos en los dos extremos de la propia barra, alambre, fleje o elemento similar de refuerzo 3. En el caso de realizar el anclaje mediante solape de tramos de la barra, alambre, fleje o elemento similar de refuerzo 3, éste se puede realizar mediante dispositivos auxiliares habituales como manguitos, tuercas, pernos en U o abrazaderas. According to this embodiment according to the continuous helical arrangement around the structural supporting element 1, the anchoring of the bar, strapping, wire or similar reinforcing element 3 is arranged at the beginning and at the end thereof, and can be performed by connected overlap of two sections at one of the ends of the bar, wire, strapping or similar reinforcement element 3, while the other section is fixed to the structural bearing element 1. Alternatively, the anchoring of the bar, wire, strapping or similar reinforcement element 3 around the structural bearing element 1 can be carried out by means of a connected overlap of two sections in both ends of the bar, wire, strapping or similar reinforcement element 3. In the case of anchoring by overlapping sections of the bar, wire, strapping or similar reinforcement element 3, this can be done by usual auxiliary devices such as sleeves, nuts, U-bolts or clamps.
Como alternativa a la disposición helicoidal continua de la barra, alambre, fleje o elemento similar de refuerzo 3 alrededor del elemento portante estructural 1 , según otra realización particular existe una disposición discreta de una o varias barras, alambres o elemento similar de refuerzo 3 que puede estar dispuesto en "U" o en "O" alrededor del elemento portante estructural 1 , tal y como se puede apreciar en las figuras 4, 6, 9 y 10.  As an alternative to the continuous helical arrangement of the bar, wire, strapping or similar reinforcement element 3 around the structural bearing element 1, according to another particular embodiment there is a discrete arrangement of one or more bars, wires or similar reinforcement element 3 which can be arranged in "U" or "O" around the structural bearing element 1, as can be seen in Figures 4, 6, 9 and 10.
De acuerdo con esta realización según la disposición discreta de una o varias barras, alambres, flejes o elementos similares de refuerzo 3 en "U" o en "O", el anclaje del elemento de refuerzo 3 se realiza mediante la fijación de éste al elemento portante estructural 1 . De forma preferente, este anclaje se realiza de forma autoanclada, conectando por solape los tramos iniciales y finales de la propia barra, alambre, fleje o elemento similar de refuerzo 3, o mediante al menos una placa auxiliar 4 y las correspondientes tuercas o pernos 5 para el anclaje, aunque podrían utilizarse medios alternativos.  According to this embodiment according to the discrete arrangement of one or more bars, wires, strips or similar reinforcement elements 3 in "U" or "O", the anchoring of the reinforcement element 3 is carried out by fixing it to the element structural bearing 1. Preferably, this anchoring is carried out in an auto-anchored manner, by overlapping the initial and final sections of the bar, wire, strapping or similar reinforcement element 3, or by at least one auxiliary plate 4 and the corresponding nuts or bolts 5 for anchoring, although alternative means could be used.
En general, los anclajes podrán ser de tipo atornillado y deberán diseñarse para soportar siempre la máxima fuerza posible en la barra, alambre, fleje o elemento similar de refuerzo 3.  In general, the anchors may be bolted and should be designed to always withstand the maximum possible force on the bar, wire, strap or similar reinforcement element 3.
De acuerdo con una realización particular de la invención, en el caso en que los elementos de refuerzo 3 sean flejes, el anclaje de éstos alrededor del elemento portante estructural 1 se realiza mediante la unión de los tramos que se solapan entre sí mediante una hebilla 6 y el tesado y doblado de dichos tramos mediante una tensadora de flejes soportada por dicha hebilla 6. Posteriormente se puede realizar el anclaje definitivo mediante clavos, tornillos o remaches, en este último caso de forma autotensada sin perforar la estructura portante 1 a reforzar.  According to a particular embodiment of the invention, in the case where the reinforcement elements 3 are straps, the anchoring of these around the structural bearing element 1 is carried out by joining the sections that overlap each other by means of a buckle 6 and the testing and bending of said sections by means of a strapping tensioner supported by said buckle 6. Subsequently, the final anchoring can be carried out by means of nails, screws or rivets, in the latter case self-tensioned without piercing the supporting structure 1 to be reinforced.
Según diferentes realizaciones particulares de la invención, la activación de la barra, alambre, fleje o elemento similar de refuerzo 3 mediante calentamiento de ésta se puede conseguir mediante diferentes medios tales como pistola de aire caliente, soplete, mantas térmicas, o el paso de electricidad a lo largo de dicha barra, fleje alambre o elemento similiar de refuerzo 3, gracias a la ley de Joule.  According to different particular embodiments of the invention, the activation of the bar, wire, strapping or similar reinforcement element 3 by heating it can be achieved by different means such as hot air gun, torch, thermal blankets, or the passage of electricity along said bar, wire strap or similar reinforcement element 3, thanks to Joule's law.
De forma particular, y sobre todo si las barras, alambres, flejes o elementos similares de refuerzo 3 de aleación de forma (SMAs) no tienen una elevada ductilidad, se puede realizar una etapa previa a la disposición de la barra, alambre, fleje o elemento auxiliar de refuerzo 3 alrededor del elemento portante estructural 1 , consistente en un redondeo previo de los cantos de dicho elemento portante estructural. De esta forma se evitará la existencia de vértices a 90e que podrían dañar la barra, alambre, fleje o elemento similar de refuerzo 3. Particularly, and especially if the bars, wires, strips or similar reinforcement elements 3 of form alloy (SMAs) do not have high ductility, a stage prior to the arrangement of the bar, wire, strap or auxiliary reinforcing element 3 can be carried out around the structural bearing element 1, consisting of a previous rounding of the edges of said structural bearing element. This will avoid the existence of vertices at 90 e that could damage the bar, wire, strap or similar reinforcement element 3.
Una realización particular de la invención incorpora una etapa adicional de recubrimiento de las barras, alambres, flejes o elementos similares de refuerzo 3 tras su activación, mediante diferentes medios tales como material proyectado, mortero, placas de yeso y combinaciones de éstos. Este recubrimiento se puede realizar para proteger al sistema de refuerzo frente a fuego o diferentes condiciones ambientales adversas. En este caso se deberá inicialmente tratar la superficie del elemento portante estructural 1 a reforzar para incrementar su rugosidad. Ello será posible mediante el uso de hidrojet, chorro de arena, o repicado por métodos manuales o mecánicos, antes de realizar la disposición de la barra, alambre o elemento similar de refuerzo 3. Según esta realización particular, el método puede incluir una etapa previa de realización de ranuras o rozas en el elemento portante estructural 1 para la disposición de las barras, alambres o elementos similares de refuerzo 3 en dichas ranuras, y el recubrimiento posterior de éstas mediante los medios indicados anteriormente. Las ranuras se realizarán mediante rozadora o medios similares.  A particular embodiment of the invention incorporates an additional step of coating the bars, wires, strips or similar reinforcement elements 3 after activation, by different means such as projected material, mortar, plasterboard and combinations thereof. This coating can be done to protect the reinforcement system against fire or different adverse environmental conditions. In this case, the surface of the structural bearing element 1 to be reinforced must initially be treated to increase its roughness. This will be possible through the use of hydrojet, sandblasting, or repeated by manual or mechanical methods, before arranging the bar, wire or similar reinforcement element 3. According to this particular embodiment, the method may include a previous stage of realization of grooves or rubs in the structural supporting element 1 for the arrangement of the bars, wires or similar reinforcement elements 3 in said grooves, and the subsequent coating thereof by means indicated above. The grooves will be made using a brush or similar means.
La protección frente al fuego se ve incrementada además por el hecho de no tener que utilizar necesariamente resinas o adhesivos, lo cual era habitual en los sistemas anteriores del esado de la técnica de refuerzo mediante fibras reforzadas de polímeros.  The protection against fire is further increased by the fact of not necessarily having to use resins or adhesives, which was common in the previous systems of the state of the reinforcement technique by polymer reinforced fibers.
El método objeto de la presente invención se puede aplicar igualmente para refuerzos a punzonamiento en losas o ábacos de forjados reticulares, de forma similar al aplicado para vigas, teniendo en cuenta que en el caso de punzonamiento en losas o ábacos de forjados reticulares los refuerzos se dispondrán en dos direcciones del espacio a partir del pilar, tal y como se muestra en la figura 13. Dichos refuerzos requerirán de varias perforaciones previas en la losa para poder disponer la barra, alambre, fleje o elemento similar de refuerzo 3 que envuelva el elemento portante estructural. Nótese que en las zonas a reforzar situadas alrededor de un pilar interior estos refuerzos se disponen como mínimo cuatro veces (dos sentidos a partir del pilar en dos direcciones). El proceso de disposición de la barra, alambre, fleje o elemento similar de refuerzo 3 es el mismo que el indicado anteriormente, añadiendo el paso previo de perforación de la losa para la disposición posterior del refuerzo. También es posible el uso de la barra, alambre, fleje o elemento similar de refuerzo 3 en "U" en este caso. El método es válido igualmente para vigas, viguetas o nervios de forjados con sección transversal en "T". The method object of the present invention can also be applied for reinforcements to punching in slabs or abacus of reticular slabs, similar to that applied to beams, taking into account that in the case of punching in slabs or abacus of reticular slabs the reinforcements are they will have in two directions of the space from the pillar, as shown in figure 13. Said reinforcements will require several previous perforations in the slab to be able to arrange the bar, wire, strap or similar reinforcement element 3 that surrounds the element structural bearing Note that in the areas to be reinforced around an inner pillar, these reinforcements are arranged at least four times (two directions from the pillar in two directions). The process of arranging the bar, wire, strapping or similar reinforcement element 3 is the same as indicated above, adding the previous step of drilling the slab for the subsequent arrangement of the reinforcement. It is also possible the use of the bar, wire, strap or similar reinforcement element 3 in "U" in this case. The method is also valid for beams, joists or ribs of slabs with a "T" cross section.
Otro objeto de la presente invención es un sistema de refuerzo activo frente a esfuerzo cortante o punzonamiento en elementos portantes estructurales.  Another object of the present invention is an active reinforcement system against shear stress or punching in structural bearing elements.
Tal y como se puede observar en las figuras, el sistema presenta al menos un elemento de refuerzo lineal 3 de aleación con memoria de forma en fase martensítica parcial o total, anclable alrededor del elemento portante estructural 1 . Particularmente este elemento de refuerzo lineal 3 puede consistir en una barra, fleje, alambre o elemento similar, pero la característica esencial es que es un elemento de refuerzo lineal, es decir, con una dimensión claramente predominante sobre el resto.  As can be seen in the figures, the system has at least one linear reinforcement element 3 made of alloy with memory of partial or total martensitic phase shape, anchorable around the structural bearing element 1. Particularly this linear reinforcement element 3 may consist of a bar, strap, wire or similar element, but the essential characteristic is that it is a linear reinforcement element, that is, with a clearly predominant dimension over the rest.
De forma particular, esta aleación con memoria de forma tiene unas características necesarias para llevar a cabo el refuerzo de forma óptima, como son que presenta estructura cristalina en fase martensítica parcial o total a temperatura ambiente, que tiene una temperatura final de transformación de fase martensítica a austenítica situada entre 100eC y 250eC, pudiendo variar esta temperatura en función de la aleación utilizada, y que tiene una temperatura inicial de transformación directa de fase austenítica a fase martensítica por debajo de la temperatura ambiente de trabajo del elemento portante estructural 1 , preferiblemente a temperaturas por debajo de -50eC, para no realizar dicha transformación directa en condiciones de trabajo. Preferentemente, la aleación con memoria de forma es tal que genera una tensión de recuperación bajo deformación impedida en la transformación de fase martensítica a austenítica de al menos 200 MPa. In particular, this shape memory alloy has characteristics necessary to carry out the reinforcement optimally, such as that it has a crystalline structure in partial or total martensitic phase at room temperature, which has a final martensitic phase transformation temperature. a austenitic located between 100 and C and 250 and C, this temperature can vary depending on the alloy used, and has an initial temperature of direct transformation from austenitic phase to martensitic phase below the ambient working temperature of the structural bearing element 1, preferably at temperatures below -50 C and for not performing said direct transformation into working conditions. Preferably, the shape memory alloy is such that it generates a recovery strain under deformation prevented in the transformation of martensitic to austenitic phase of at least 200 MPa.
Particularmente, la aleación con memoria de forma puede ser Ni-Ti-Nb, o bien Fe-Mn-Si, con la posible incorporación de otros componentes en menor proporción, aunque podría ser cualquier aleación con memoria de forma que cumpla con los requisitos indicados anteriormente.  Particularly, the shape memory alloy can be Ni-Ti-Nb, or Fe-Mn-Si, with the possible incorporation of other components in a smaller proportion, although it could be any memory alloy in a way that meets the indicated requirements previously.
Una vez descrita de forma clara la invención, se hace constar que las realizaciones particulares anteriormente descritas son susceptibles de modificaciones de detalle siempre que no alteren el principio fundamental y la esencia de la invención.  Once the invention is clearly described, it is noted that the particular embodiments described above are subject to modifications in detail as long as they do not alter the fundamental principle and essence of the invention.

Claims

REIVINDICACIONES
1 . Método de refuerzo activo frente a esfuerzo cortante o punzonamiento en elementos portantes estructurales, siendo dichos elementos portantes estructurales (1 ) del tipo de vigas, pilares y losas, caracterizado por que comprende las etapas de one . Active reinforcement method against shear stress or punching in structural supporting elements, said structural supporting elements (1) being of the type of beams, pillars and slabs, characterized in that it comprises the steps of
disposición de al menos un elemento de refuerzo lineal (3) de aleación con memoria de forma pre-estirada en fase martensítica alrededor del elemento portante de estructuras (1 ) a reforzar, de forma tal que dicha barra de refuerzo (3) queda dispuesta transversalmente a una fisura (2) generada, por el esfuerzo cortante o punzonamiento,  arrangement of at least one linear reinforcement element (3) of memory alloy pre-stretched in the martensitic phase around the bearing element of structures (1) to be reinforced, such that said reinforcement bar (3) is arranged transversely to a fissure (2) generated, by the shear force or punching,
anclaje del elemento de refuerzo lineal (3) alrededor del elemento portante estructural (1 ), realizándose dicho anclaje mediante solape de al menos dos tramos del propio elemento de refuerzo lineal (3)  anchoring of the linear reinforcement element (3) around the structural bearing element (1), said anchor being made by overlapping at least two sections of the linear reinforcement element itself (3)
activación del elemento de refuerzo lineal (3) mediante calentamiento de éste, originando la transformación del elemento de refuerzo lineal (3) de fase martensítica a fase austenítica y produciendo un efecto de pretensado postesado de confinamiento en el elemento portante estructural (1 ).  activation of the linear reinforcement element (3) by heating it, causing the transformation of the linear reinforcement element (3) from martensitic phase to austenitic phase and producing a prestressed prestressing effect of confinement in the structural bearing element (1).
2. Método según la reivindicación 1 , caracterizado por que el anclaje del elemento de refuerzo lineal (3) alrededor del elemento portante estructural (1 ) se realiza mediante la fijación de al menos un tramo del refuerzo lineal (3) al elemento portante estructural (1 ). Method according to claim 1, characterized in that the anchoring of the linear reinforcement element (3) around the structural bearing element (1) is carried out by fixing at least one section of the linear reinforcement (3) to the structural bearing element ( one ).
3. Método según cualquiera de las reivindicaciones anteriores, caracterizado por que la disposición del elemento de refuerzo lineal (3) se realiza de forma sustancialmente helicoidal continua alrededor del elemento portante estructural (1 ). Method according to any one of the preceding claims, characterized in that the arrangement of the linear reinforcement element (3) is carried out in a substantially helical continuous manner around the structural bearing element (1).
4. Método según la reivindicación anterior, caracterizado por que la disposición de forma sustancialmente helicoidal del elemento de refuerzo lineal (3) se realiza de forma tal que Method according to the preceding claim, characterized in that the substantially helical arrangement of the linear reinforcement element (3) is carried out in such a way that
unos tramos del elemento de refuerzo lineal (3) quedan dispuestos en disposición perpendicular a la directriz del elemento portante estructural (1 ) y  sections of the linear reinforcement element (3) are arranged perpendicular to the guideline of the structural bearing element (1) and
unos tramos de dicho elemento de refuerzo lineal (3) quedan dispuestos inclinados con respecto a la directriz del elemento portante estructural (1 ). sections of said linear reinforcement element (3) are arranged inclined with respect to the guideline of the structural bearing element (1).
5. Método según cualquiera de las reivindicaciones 1 -2, caracterizado por que la disposición del elemento de refuerzo lineal, (3) se realiza de forma discreta mediante al menos un elemento de refuerzo lineal en con una disposición seleccionada entre en "U" y en "O" alrededor del elemento portante estructural (1 ). 5. Method according to any of claims 1-2, characterized in that the arrangement of the linear reinforcement element, (3) is carried out discreetly by means of at least one linear reinforcement element in with an arrangement selected between "U" and at "O" around the structural bearing element (1).
6. Método según la reivindicación anterior, caracterizado por que el anclaje del elemento de refuerzo lineal (3) alrededor del elemento portante estructural (1 ) se realiza mediante al menos una placa auxiliar (4) y tuercas o pernos (5). Method according to the preceding claim, characterized in that the anchoring of the linear reinforcement element (3) around the structural bearing element (1) is carried out by at least one auxiliary plate (4) and nuts or bolts (5).
7. Método según cualquiera de las reivindicaciones anteriores, caracterizado por que el anclaje del elemento de refuerzo lineal (3) alrededor del elemento portante estructural (1 ) se realiza mediante la unión de los tramos que se solapan entre sí mediante una hebilla (6) y el tesado y doblado de dichos tramos mediante una tensadora de flejes, que es soportada por la hebilla (6). Method according to any of the preceding claims, characterized in that the anchoring of the linear reinforcement element (3) around the structural bearing element (1) is carried out by joining the sections that overlap each other by means of a buckle (6) and the testing and bending of said sections by means of a strap tensioner, which is supported by the buckle (6).
8. Método según cualquiera de las reivindicaciones anteriores, caracterizado por que la activación del elemento de refuerzo lineal (3) mediante calentamiento de éste se realiza mediante medios seleccionados entre pistola de aire caliente, soplete, mantas térmicas o paso de electricidad a lo largo de dicha barra de refuerzo (3). Method according to any one of the preceding claims, characterized in that the activation of the linear reinforcement element (3) by heating it is carried out by means selected from hot air gun, blowtorch, thermal blankets or passage of electricity along said reinforcement bar (3).
9. Método según cualquiera de las reivindicaciones anteriores, caracterizado por que previamente a la disposición del elemento de refuerzo lineal (3) alrededor del elemento portante estructural (1 ) se realiza un redondeo de los cantos de dicho elemento portante estructural (1 ). Method according to any of the preceding claims, characterized in that prior to the arrangement of the linear reinforcement element (3) around the structural bearing element (1) a rounding of the edges of said structural bearing element (1) is performed.
10. Método según cualquiera de las reivindicaciones anteriores, caracterizado por que comprende una etapa adicional de recubrimiento del o elemento de refuerzo lineal (3) tras su activación mediante medios seleccionados entre material proyectado, mortero, placas de yeso y combinación de ellos. Method according to any of the preceding claims, characterized in that it comprises an additional stage of coating the linear reinforcement element (3) after its activation by means selected from projected material, mortar, plasterboard and combination thereof.
1 1 . Método según cualquiera de las reivindicaciones anteriores, caracterizado por que comprende una etapa previa de realización de ranuras en el elemento portante estructural (1 ) para la disposición de al menos un elemento de refuerzo lineal (3) en dichas ranuras. eleven . Method according to any of the preceding claims, characterized in that it comprises a previous stage of realization of grooves in the structural bearing element (1) for the arrangement of at least one linear reinforcement element (3) in said grooves.
12. Sistema de refuerzo activo frente a esfuerzo cortante o punzonamiento en elementos portantes estructurales, caracterizado por que comprende al menos un elemento de refuerzo lineal (3) de aleación con memoria de forma en fase martensítica anclable alrededor del elemento portante estructural (1 ). 12. Active reinforcement system against shear stress or punching in structural supporting elements, characterized in that it comprises at least one linear reinforcement element (3) made of alloy with memory in the martensitic phase that can be anchored around the structural bearing element (1).
13. Sistema de refuerzo activo según la reivindicación 12, caracterizado por que la aleación con memoria de forma 13. Active reinforcement system according to claim 12, characterized in that the shape memory alloy
presenta estructura cristalina en fase martensítica, a temperatura ambiente, - tiene una temperatura final de transformación de fase martensítica a austenítica situada entre 100eC y 250eC, it has a crystalline structure in the martensitic phase, at room temperature, - it has a final transformation temperature of the martensitic to austenitic phase between 100 and C and 250 and C,
tiene una temperatura inicial de transformación directa de fase austenítica a fase martensítica por debajo de la temperatura ambiente de trabajo del elemento portante de estructuras (1 ),  it has an initial temperature of direct transformation from austenitic phase to martensitic phase below the working ambient temperature of the structure bearing element (1),
- y genera una tensión de recuperación bajo deformación impedida en la transformación de fase martensítica a austenítica de al menos 200 MPa. - and generates a recovery strain under deformation prevented in the transformation of martensitic to austenitic phase of at least 200 MPa.
14. Sistema de refuerzo activo según la reivindicación anterior, caracterizado por que la aleación con memoria de forma está seleccionada entre las familias de aleaciones Ni-Ti-Nb y Fe-Mn-Si. 14. Active reinforcement system according to the preceding claim, characterized in that the shape memory alloy is selected from the Ni-Ti-Nb and Fe-Mn-Si alloy families.
15. Sistema de refuerzo activo según cualquiera de las reivindicaciones 12-14, caracterizado por que el elemento de refuerzo lineal (3) está seleccionado entre barras, alambres, flejes y combinación de los anteriores. 15. Active reinforcement system according to any of claims 12-14, characterized in that the linear reinforcement element (3) is selected from bars, wires, strips and combination of the foregoing.
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