EP3168384A1 - Strukturelles verstärkungssystem mit intern durch haftung verankerten verstärkungen - Google Patents

Strukturelles verstärkungssystem mit intern durch haftung verankerten verstärkungen Download PDF

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Publication number
EP3168384A1
EP3168384A1 EP15754011.3A EP15754011A EP3168384A1 EP 3168384 A1 EP3168384 A1 EP 3168384A1 EP 15754011 A EP15754011 A EP 15754011A EP 3168384 A1 EP3168384 A1 EP 3168384A1
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EP
European Patent Office
Prior art keywords
reinforcement
structural
strengthening
structural element
anchorage
Prior art date
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EP15754011.3A
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English (en)
French (fr)
Inventor
Carlos Manuel Chastre Rodrigues
Hugo Emanuel CHARRINHO DA COSTA BISCAIA
Noel Isidoro MATOS FRANCO
António Carlos PEREIRA JANES MONTEIRO
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Faculdade de Ciencias e Tecnologia da Universidade Nova de Lisboa
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Faculdade de Ciencias e Tecnologia da Universidade Nova de Lisboa
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Publication of EP3168384A1 publication Critical patent/EP3168384A1/de
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    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
    • E04C5/08—Members specially adapted to be used in prestressed constructions
    • E04C5/12—Anchoring devices
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
    • E04C5/08—Members specially adapted to be used in prestressed constructions
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
    • E04C5/08—Members specially adapted to be used in prestressed constructions
    • E04C5/085—Tensile members made of fiber reinforced plastics
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
    • E04C5/08—Members specially adapted to be used in prestressed constructions
    • E04C5/12—Anchoring devices
    • E04C5/127—The tensile members being made of fiber reinforced plastics
    • 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
    • E04G2023/0251—Increasing or restoring the load-bearing capacity of building construction elements by using fiber reinforced plastic 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
    • 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
    • E04G2023/0251—Increasing or restoring the load-bearing capacity of building construction elements by using fiber reinforced plastic elements
    • E04G2023/0262—Devices specifically adapted for anchoring the fiber reinforced plastic elements, e.g. to avoid peeling off

Definitions

  • a system to strengthen structural elements is described, where reinforcement is applied to them, these structural elements being footings, caisson foundation, pile foundations, beam foundations, raft foundations, columns, beams, arches, vaults, slabs, cantilevers, corbels, or walls.
  • One of the solutions to strengthen structural elements is based on the addition of reinforcement to the elements to be strengthened, either by applying post-tensioning or not, the former being the so-called “active strengthening” and the latter the “passive strengthening ".
  • active strengthening makes it possible to take advantage of the materials capabilities and dramatically improve the behavior of the strengthened element under service conditions by reducing its deformations.
  • active strengthening also decreases the opening of cracks.
  • the application of active strengthening with post-tensioned reinforcement consists of fixing the strengthening reinforcement to the element to be strengthened, by tensioning it and thus introducing compressive forces in the element.
  • the use of active strengthening requires the use of strengthening reinforcement with high tensile strength, low relaxation and preferably linear elastic behavior. In this type of strengthening it is common to use high strength steel (prestressing steel) or carbon-fiber laminated reinforcement.
  • the application of the active strengthening is usually performed in two ways: with adherent post-tensioned active reinforcement (i) or unbonded post-tensioned active reinforcement (ii).
  • the implementation procedure generally comprises the surface preparation of the element in order to improve the adhesion of the adherence agent; the application of the adherence agent along the surface; and the application of pre-tensioned strengthening reinforcement with the aid of anchorages.
  • the adherence agent cure with this strengthening procedure, the transfer of forces between the structural element and the strengthening reinforcement occurs via the adherence agent essentially by shear forces.
  • the transfer of forces between the strengthening reinforcement and the structural element to be strengthened is carried out continuously and transmitted through a adherence agent, whereas in the active strengthening with unbonded post-tensioning (ii) the forces are occasionally transmitted to the anchorages and deviators.
  • the adherent post-tensioned active strengthening (i) is usually externally bonded to the faces of the structural element to be strengthened or within an additional layer applied to it.
  • the success of the solution depends on the ability of the strengthening reinforcement to transmit the forces to the structural element. It is, therefore, essential that the strengthening reinforcement is properly anchored to the structural element in order to avoid losses of prestressing, which are more likely to happen in (ii).
  • passive strengthening reinforcement for strengthening in bending flat and linear structural elements such as columns, beams and slabs is usually carried out in two ways: i) externally bonded to the element or ii) near-surface mounted to the structural element, this surface being also called cover in case of reinforced concrete elements. These two application procedures of reinforcement have been widely applied and well accepted in the strengthening and repair of structures.
  • the application procedure generally comprises the preparation of the surface of the element to be strengthened in order to improve the adhesive bonding; the application of the adhesive along the surface; and the application of strengthening reinforcement.
  • This strengthening procedure the transfer of forces between the structural element and the strengthening reinforcement occurs through the adhesive essentially by shear forces.
  • the application procedure begins with the cutting of grooves into the surface layer of the structural element to be strengthened (with appropriate dimensions for the strengthening reinforcement); next, the grooves are partially filled with adhesive and the strengthening reinforcement is introduced; finally, the grooves are completely filled with adhesive.
  • the strengthening reinforcement has the advantage of being partially embedded in the element, allowing the forces transmitted to the strengthened element to occur inside it, what does not happen with the externally bonded reinforcement.
  • Mechanical anchorage are usually performed by introducing mechanical or chemical anchors in the element to be strengthened in order to have a compressive force in the normal direction to the surface of the strengthening reinforcement. In this way, and with suitable design, it is possible to mobilize the maximum tensile capacity of the strengthening reinforcement.
  • the other way to improve the behavior of strengthened elements with the addition of reinforcement is to increase the anchoring area in the zones of potential risk of premature rupture, particularly at the ends and in zones where concentrated loads are applied.
  • reinforcement is applied in the transverse direction of the strengthening reinforcement and, whenever possible, partially or completely surrounding the cross-section of the structural element. This solution is often used when the intention is to strengthen the structural element simultaneously in bending and shear, and it improves the strengthening behavior in the ultimate limit state.
  • the document DE2510262 shows a strengthening procedure consisting, as the previous one, in grooves which are opened on the element to be strengthened and filled, in this case, with binder or epoxy resin reinforced with fibers.
  • This document also considers the prior inclusion of fibers on the grooves and subsequent filling with resins or other binder materials. In the latter procedure it is also contemplated the possibility of introducing fibers at the tops of the element between the grooves, improving this way the bearing capacity of the anchorage zone of the fibers.
  • the opening of grooves conditions the application of this disclosure in elements whose reinforcement, or fibers, cannot be cut, such as reinforced concrete elements with reinforcement perpendicular to the direction of the strengthening reinforcement in the anchorage zone.
  • the patent document US 6389775 describes a way of anchoring the ends of the externally bonded reinforcement via anchoring straps.
  • the anchoring straps - two for each end - are used and can either or not have a slot to accommodate the end of the strengthening reinforcement, on which an increased thickness and / or width is performed by adding the binder matrix and moving away the fibers and / or overlapping the layers of the strengthening reinforcement.
  • the anchoring of the strengthening reinforcement to the anchor plates is performed with adhesive material, and the fastening of the anchor plates to the element is done via high strength securing screws traversing the two plates. By fixing the plates with screws, the compressions on the strengthening reinforcement increase, which improves the performance of the anchorage.
  • thermosetting polymer matrix of the reinforcement fibers is removed by heating or chemical exposure in order to facilitate the rearrangement of the fibers in the anchorage zone. This way, it is possible to adjust the reinforcement fibers in these areas, being the matrix later put back by impregnation.
  • US 20110197540 presents an anchorage device for elongated reinforcement, such as fiber-reinforced polymers, and polymers reinforced with metallic bars or cables.
  • This device in its different variations, consists of a block with a hole where the strengthening reinforcement and at least two fastening devices are introduced. These fastening devices allow the introduction of compression in the strengthening reinforcement by contracting the perimeter of the hole, which is achieved by the existence of a slot traversing the anchorage device from the hole to the lateral surface.
  • This anchorage device can be fixed to the structure via screws.
  • EP2083133 describes a mechanical device which is applied outside the element to be strengthened and uses mechanical anchors to transmit shear forces between the device and the element to be strengthened.
  • the invention uses two curved metal pieces outside the element in a perpendicular plane to the face of the element, being the reinforcement introduced between the two curved metal pieces and later tightened via screws.
  • PT 103785 a post-tensioning system with anchorage by adherence for concrete structures is presented.
  • the system consists in installing prestress anchored by adherence, the prestressing steel being tensioned with the aid of provisional anchors. After the adhesive cure, the prestress is released from the temporary anchors and transferred to the concrete.
  • the anchorage is performed after tensioning the strengthening reinforcement, thus not allowing further changes in the value of the installed force in the strengthening reinforcement.
  • the present disclosure describes a strengthening system which solves the problem of premature failure that normally occurs in structural elements strengthened with post-installed reinforcement, with no need to change geometrically the strengthening reinforcement, or to apply additional devices in the anchorage zones, therefore allowing the mobilization of the ultimate tensile strength of the strengthening reinforcement and providing greater confidence in the use of strengthening with post-installed reinforcement. It can be applied to elements with reinforcement or fibers perpendicular to the direction of the strengthening reinforcement in the anchorage zone. In addition the proposed system also makes it possible to change the value of the installed force in the strengthening reinforcement, when using active strengthening.
  • the present disclosure describes a structural strengthening system comprising at least one post-installed strengthening reinforcement (1), whose profile has maximum eccentricity in the regions with higher tension, anchored at its core by a adherence agent placed along a straight section (3) with an inclination that can range between 0.5° and 100° (8) and is located after the transition curve (2) that exists between this straight section (3) and the surface of the element.
  • the application method comprises the steps of opening holes (3) for anchoring the strengthening reinforcement in the core of the element to be strengthened; implementation of the transition curve (2) between the hole and the surface of the element to be strengthened; application of a adherence agent into the anchorage hole and application of the strengthening reinforcement (1); and, if an active system is intended, changing the value of force installed in the strengthening reinforcement (1).
  • the holes may be previously drilled mechanically with the shapes and dimensions of the cross sections, which are dependent on the dimensions and shapes of the strengthening reinforcement and with the minimum depth conditioned to the anchorage length (3) required for the transfer of force by adherence to the structural element, and they can pass completely through the element (12).
  • the holes may be formed during the manufacturing process of the structural element or in tubular devices (16) applied to it, whenever the element for physical, mechanical or geometric reasons, does not allow the opening of the holes.
  • the anchorage zone (3) corresponds to the area where the transfer of stresses between the strengthening reinforcement and the core of the structural element (6) to be strengthened occur.
  • a hole is drilled in the core of the structural element (6) and the adherence agent (4), and the strengthening reinforcement (1) is applied within the hole (3).
  • tubular devices (16) are used for this purpose.
  • the change in the alignment of the strengthening reinforcement can be made via a transition curve (2) performed directly on the element to be strengthened, with the opening of a slot or by placing a prefabricated deviator device (5) with the same shape of the curve as if it were deviation saddles or metal profiles, but not being limited to these.
  • the deviation angle, as well as the shape of the curve may vary depending on the materials of the strengthening reinforcement, of the adherence agent and of the characteristics of the materials of the structural elements to be strengthened. It varies between 0.5° and 100°, and the shape may be of a semicircle, an ellipse, a parabola, a hyperbola, a clothoid or any other shape derived or composed by these ones.
  • a preferred embodiment of this strengthening system is to use prefabricated deviator devices (5) applied to the transition curve zone.
  • This structural strengthening system uses a adherence agent (4), also called adhesive, to anchor and protect the strengthening reinforcement inside the element, an adhesive which is compatible with the materials of the structural element, as well as with the strengthening reinforcement. It consists of a material identical to the one of the structural element to be strengthened or another material with better characteristics of adhesion, of resistance to environmental agents and of physical and chemical protection of the strengthened element.
  • the adherence agent used can be either natural or synthetic, among which are cement mortars and polymeric resins or other materials.
  • this strengthening system may also comprise the step of applying drains and injection tubes (23) in the holes, sealing them, in case adherence agents with low viscosity are used.
  • This strengthening system uses strengthening reinforcement in bars, strands, wires, strips, sheets, laminates or others with linear, straight or curved development, which can be bonded to the surface of the element or inserted in its cover, or even use other forms of application that already exist or may come into existence.
  • the materials of the strengthening reinforcement include the following constitutions: steel; fabrics or composite laminates reinforced with carbon-fibers, glass, basalt, graphene or aramid; shape memory alloys; metallic strengthening materials, polymeric, composites, mixed or even other materials that may come into existence.
  • the profile of the strengthening reinforcement has maximum eccentricity in the regions of higher tensions.
  • This structural strengthening system may also comprise an initial step of surface preparation, in case of externally bonded reinforcement; a step of opening the grooves in case of near-surface mounted reinforcement, or a step of application of prefabricated deviator devices (5) when the unbonded reinforcement is applied.
  • the structural strengthening system may also comprise the step of applying a temporary support for the strengthening reinforcement when the strengthening is not carried out on the upper surface of the element.
  • This temporary support may be either a mechanical device fixed to the element, a propping system (20), among others.
  • This structural strengthening system is characterized by its ability to strengthen structures and structural elements in bending and shear.
  • These structural elements can be linear, flat or curved, such as slabs, cantilevers, corbels, beams, columns, shear walls, footings, caisson foundation, pile foundations, beam foundations, raft foundations, arches and vaults, walls or others, and are made of masonry, wood, concrete, metal, composites, mixed, or other materials.
  • the system presented comprises at least one structural element, one strengthening reinforcement, one anchorage zone with a hole (3) in order to anchor the strengthening reinforcement to the structural element to be strengthened, one transition curve (2) between the hole and the surface which allows the transition of the strengthening reinforcement to the anchorage zone, one adherence agent inside the hole or on its surface (4) and one strengthening reinforcement (1) whose profile has maximum eccentricity in the region of higher tensions.
  • the anchorage zone is geometrically delimited by the free surfaces of the structural element and by half the distance to the nearest strengthening reinforcement or, in case it exists, by the outer surface of the tubular device (16).
  • the operating principle of the system consists in anchoring by adherence the strengthening reinforcement inside the element, with the possibility of changing the installed force, after the cure of the adherence agent in one of the anchorage zones, whenever an active strengthening is intended.
  • the anchorage of the reinforcement inside the element is carried out after the change of its alignment and the drilling of holes in the structural element to be strengthened. It becomes effective after the application and cure of the adherence agent in the anchorage zone.
  • the transition curve may be performed directly on the element to be strengthened, or by placing an additional component with the shape of the curve.
  • the procedure to use the presented structural strengthening system may include, depending on the application, the following different procedures:
  • the above procedure can be modified to adapt to the characteristics of the structural element to be strengthened, in particular the adherence agent, the strengthening reinforcement or the anchorage zone characteristics.
  • the adherence agent for example, when high viscosity adherence agents are used to anchor the strengthening reinforcement inside the holes or in case externally bonded reinforcement is applied, the application of drains and injection tubes in the holes, as well as their sealing, can be left out, and the injection of the adherence agent is performed directly in the anchorage hole from the inside to the outside ( Figure 16 ).
  • the proposed strengthening system in this disclosure cannot be implemented in structural elements due to their physical, geometrical or mechanical characteristics, they should be previously prepared.
  • This preparation may consist, for example, in the injection of resins to improve the mechanical characteristics of the element, the application of a tubular device ( Figure 8 ), the partial replacement of the material of the element or the application of a prefabricated or cast in situ concrete block ( Figure 9 ), suitably secured to the element to be strengthened in order to accommodate the anchorage zones.
  • the transition curve (2) aims primarily to deviate the strengthening reinforcement into the element to be strengthened. It can have different geometric shapes: semicircular, elliptic, parabolic, hyperbolic, spiral, or other, and may even be composed of more than one geometric shape.
  • the choice of the shape for the transition curve is subject to the material of the strengthening reinforcement, the material of the element to be strengthened, the level of stress produced by the strengthening reinforcement on the intrados of the curve and the adherence agent characteristics.
  • the development of the transition curve is geometrically conditioned by its shape, and by the straight alignments of strengthening reinforcement, since the beginning and the end must be tangent to these alignments.
  • the transition curve can be performed directly on the element to be strengthened by opening of a slot, or by placing an additional component with the shape of the curve (5).
  • fillers and / or auxiliary devices may either or not be placed in order to ensure a proper fit of the strengthening reinforcement to the shape of the curve.
  • the adherence agent may be any material whose properties guarantee the transmission by adhesion of the forces between the strengthening reinforcement and the structural element.
  • the polymeric resins epoxy based, methacrylate or urethane
  • mortars cement or polymeric
  • other materials with similar characteristics that already exist or may come into existence.
  • the adherence agent should provide physical and chemical protection to the strengthening and be compatible with the material of the element to be strengthened.
  • the reinforcement temporary support system to includes any procedure that allows the reinforcement to sustain itself until the adherence agent acquires strength.
  • the temporary supports is included the application of mechanical devices fixed to the element (21, 22), propping systems (20), and others.
  • the holes for the anchorage of the strengthening reinforcement may have any shape and size, being, however, dependent on the shape and size of the cross sections of the strengthening reinforcement.
  • the minimum depth of the holes is subject to the anchorage length required for the transfer of the force by adherence and can pass completely through the structural elements.
  • the holes can be mechanically or manually opened, leaving a negative in the element during the manufacturing process, or by placing a tubular device fixed to the element within which the strengthening reinforcement is anchored via an adherence agent (4).
  • the strengthening reinforcement can be installed continuously, passing completely through the structural elements (12), thereby allowing the strengthening reinforcement to follow the profile of the bending moment diagrams.
  • the reinforcement profile has a maximum eccentricity in the regions of higher tensions.
  • the anchorage zones are crucial for the success of strengthening and, if performed according to the present invention, they allow the following, among others:
  • the anchorage of the strengthening reinforcement inside the structural elements allows greater corrosion protection in the anchorage zones, reducing or even eliminating the need to apply anticorrosion protection systems in the strengthening reinforcement in these areas.
  • strengthening reinforcement As the strengthening reinforcement is anchored inside the strengthened element, resistance to fire is improved when compared to the traditional externally bonded reinforcement solutions and near-surface mounted reinforcement.
  • strengthening reinforcement and adherence agents with high performance at high temperatures it is possible to strengthen structural elements which may be subject to fire situations, thereby reducing the passive protection system of the strengthening reinforcement.
  • the presented system can be used in the strengthening of linear elements, either flat or curved, such as footings, caisson foundation, pile foundations, beam foundations, raft foundations, columns, beams, arches, vaults, slabs, cantilevers, corbels or walls; in concrete (single, reinforced, pre- or post-stressed, composite, with fibers), wood (solid, glued laminated, particle board), masonry (stone, adobe, rammed earth, brick, cement mortar), steel or polymers (plastics) or any other structural material where it is possible to carry out the anchorage by adherence of the strengthening reinforcement.
  • linear elements either flat or curved, such as footings, caisson foundation, pile foundations, beam foundations, raft foundations, columns, beams, arches, vaults, slabs, cantilevers, corbels or walls; in concrete (single, reinforced, pre- or post-stressed, composite, with fibers), wood (solid, glued laminated, particle board), masonry (stone,
  • strengthening reinforcement steel reinforcement, fiber-reinforced polymers with carbon, glass, basalt, graphene, aramid, steel or any other composite or mixed materials with strengthening purpose and whose behavior is similar to the aforementioned.
  • the presented system is not limited to strengthening solutions with externally bonded reinforcement or near-surface mounted reinforcement. It can also be used in strengthening situations with addition of reinforcement wherever anchorage is crucial for successful strengthening.
  • This structural strengthening system may be used together with other ways of anchoring the strengthening reinforcement, thus allowing a very versatile use. It is also possible to anchor one end of the reinforcement following the procedure in the present invention and use another system or technique to anchor the other end.
  • the present structural strengthening system may comprise at least one structural element (6), one post- installed strengthening reinforcement (1) whose profile has maximum eccentricity in the zones with higher tensions, one anchorage zone (3) in the core of the structural element (6), one adherence agent (4), one straight section with an inclination which can vary between 0.5o and 100o (8), and a transition curve (2) located between this straight section and the surface of the element.
  • the system now disclosed may further comprise, in the case of the application of non-adherent strengthening, deviator devices.
  • the anchorage zone (3) of the structural strengthening system may be located in tubular devices (16) applied on the structural element (6).
  • the transition curve can have an additional component with the shape of the curve, in particular deviation saddles, deviator saddles, hot-rolled profiles or cold-rolled profiles.
  • the angle (8) of the transition curve (2), as well as its shape, may vary depending on the material of the strengthening reinforcement (1), of the adherence agent (4), and of the characteristics of the material of the elements to be strengthened.
  • the shape of the transition curve can be a semicircle, an ellipse, a parabola, a hyperbola, a clothoid or any other shape derived or composed by these ones.
  • the structural strengthening system may further comprise prefabricated deviator devices (5) in the transition curve zone (2) when it is necessary to ensure a proper adjustment of the reinforcement to the shape of the curve.
  • this structural strengthening system may further comprise a adherence agent in a material similar to the one of the element to be strengthened or even in another material with better characteristics of adherence, of resistance to environmental agents and of physical and chemical protection of the strengthening reinforcement and of the strengthened element.
  • the structural strengthening system may further comprise natural or synthetic adherence agents such as cement mortars, polymer resins or others.
  • the structural strengthening system may have reinforcement in bars, strands, wires, strips, laminates or others with linear, straight or curved development.
  • the structural strengthening system can have strengthening reinforcement (1) bonded to the surface of the element, inserted in the cover of the element or using another existing form of application.
  • the structural strengthening system can have strengthening reinforcement (1) in materials such as, for example, steel, laminated composites reinforced with carbon fiber, glass, basalt, graphene or aramid, shape memory alloys, metallic, polymeric, or other composites strengthening materials.
  • the structural strengthening system can modify the installed force in the strengthening reinforcement, after the adherence agent cure in the anchorage zone.
  • the structural strengthening system can strengthen to bending and shear structures and structural elements.
  • the structural strengthening system may strengthen linear structural elements, flat or curved, such as slabs, beams, columns, shear walls, footings, caisson foundation, arches and vaults, walls or others.
  • the structural strengthening system may also strengthen structural elements of masonry, wood, concrete, metal, composites, mixed, or others.
  • the present disclosure also relates to a method for installing a structural strengthening system comprising the following steps:
  • the method described above may further comprise an initial step of surface preparation, in case of externally bonded reinforcement application, and / or an initial step of grooving opening in case of near-surface mounted reinforcement on the surface of the element, and / or an initial step of the deviator devices application, when applying the non-adhered strengthening, and / or a temporary support for the strengthening reinforcement, in case the strengthening reinforcement is not applied in the top surface of the element.
  • the method described may further comprise the temporary support to the strengthening reinforcement with a device fixed to the element (21, 22), one propping system (20), among others.
  • the method described may further comprise the step of applying drains and injection tubes in the holes, with their sealing, in case of using low viscosity adherence agents.
  • the holes performed with the aforementioned method may be previously carried out by mechanically drilling systems and additionally; the holes may have shapes and dimensions of the cross sections, depending on the dimensions and shapes of the strengthening reinforcement; the previously drilled holes may have a minimum depth conditioned by the anchorage length (3) required for the transfer of force by adherence and can pass completely through the section (12).
  • the structural element (6) when the structural element (6) for physical, mechanical or geometric reasons, does not allow the drilling of holes, they can be moulded during the manufacturing process of the element or in tubular devices (16) applied to the structural element (6).
  • the transition curve (2) can be made directly in the structural element (6) to be strengthened, through the opening of a slot.
  • the transition curve can be performed by placing an additional component with the shape of the curve, as if it were, but not limited to, deviator saddles, hot-rolled profiles or cold-rolled profiles.
  • the angle (8) of the transition curve (2) may vary depending on the materials of the strengthening reinforcement (1), on the adherence agent (4), and on the characteristics of the materials of the elements to be strengthened.
  • the angle (8) of the transition curve may vary between 0.5° and 100°.
  • a adherence agent (4) also called adhesive, is used to anchor and protect the strengthening reinforcement inside the element, compatible with the materials of the structural element and with the r strengthening reinforcement.
  • structures and structural elements are strengthened in bending and shear.
  • linear structural elements - flat or curved - are strengthened, among which are slabs, beams, columns, shear walls, footings, caisson foundation, arches and vaults, walls or others.
  • structural elements in masonry, wood, concrete, metal, composites, mixed, or others are strengthened.
  • the testing setup used consists on simply supporting the sample on two supporting devices, a fixed and a movable support with dimensions of 200x200mm 2 , and applying in the upper surface level of the flange and symmetrically to the mid-span, two concentrated loads with a spacing of 1000mm. This system makes it possible to apply pure bending between the load application points and simple bending at the ends of the model.
  • the beams from group i) were built with a total length of 3300mm, 3000mm between supports, a total height of 315mm, being 225mm of the web, a width of 400mm at flange level and a width of 150mm at the web level.
  • the beams from group ii) were built with the same dimensions, except for the overall height, whose size was 300mm, 200mm of which correspond to the height of the web.
  • the concrete beams were longitudinally reinforced with three 12mm-diameter steel bars disposed close to the lower face of the web (tension area) and six 8-mm diameter steel bars arranged in the flange.
  • beams were reinforced with two-branches of 6mm-diameter steel stirrups, which were longitudinally spaced at 150mm.
  • the concrete cover of the reinforcement had 20 mm, except on the lower side of the beam webs from group i), which was 36mm-thick.
  • the concrete used in the beams from group i) had, after 28 days, an average strength to compression of 18.5MPa, which was obtained in tests with 150mm-diameter and 300mm-height cylindrical samples.
  • the 6mm-diameter reinforcing steel used in beams from group i) and the 6mm-diameter reinforcing steel used in beams from group ii) is from A500ER class.
  • the remaining ordinary reinforcing steel is from A500NR SD class.
  • the stainless steel strengthening reinforcement in a 20x5mm 2 cross-section bar is EN1.4404 class and presents average values of the limit of proportionality at 0.2% equal to 259.8 MPa and tensile strength equal to 617.8 MPa.
  • Stainless steel ribbed bar with a nominal size of 8 mm is EN1.4301 class and present an average value of limit the proportionality at 0.2% equal to 471.7MPa; and an average value of tensile strength equal to 1008.5MPa.
  • Emr elastic modulus
  • ⁇ mr maximum strain
  • the beam b) was strengthened with a laminate with a cross-section of 50x1.2mm 2 and a length of 2700mm applied over a 2mm-layer of resin r1 on the lower side of the beam web.
  • the beam c) was strengthened with four laminates which were 2700mm-long and had a cross-section of 10x1.4mm 2 , applied with resin r1 in four grooves with a 5x15mm 2 cross-section.
  • the beam d) was strengthened with four laminates with a 10x1.4mm 2 cross-section and a length of 3700mm applied to the lower side of the beam web, over a length of 2035mm.
  • This application was on a 1mm-thick resin layer r1 and anchored (3) at the ends inside 12mm-diameter holes over a length of 415mm with resin r1 and resin r2 (two laminates anchored with resin r1 and two anchored with resin r2), with a deviation angle of 33o (8) and a transition curve radius (2) of 300mm.
  • Strengthening reinforcement was applied in a staggered manner, two for each side, 72mm off-centered from the mid-span of the beam.
  • the beam b) was strengthened with two stainless steel bars with a cross-section of 20x5mm 2 and a length of 2750mm applied on a 1.5 mm resin layer r1 on the lower side of the beam web.
  • the beam c) was strengthened with four ribbed bars with a cross-section of 48.1mm 2 and a length of 2750mm inserted with resin r1 in grooves with a cross-section of 12x12mm 2 .
  • the beam d) was strengthened with two stainless steel bars with cross-section 20x5mm 2 with a length of 3015mm resin bonded with r1 on the lower side of the beam web over a length of 2000mm and anchored (2) inside 25mm-diameter holes over a length of 332mm with resin r1, with a deviation angle of 33o (8) and a radius of the transition curve of 300mm.
  • the opening of the grooves on the surface layer of the concrete beams c) from both groups was carried out with a concrete cutting grinder equipped with a diamond disk and cutting guide.
  • the holes for the anchorage of reinforcement in the beams d) from both groups were performed with a rotary hammer drill, aided by a guide device which ensured the drilling with the intended deviation angle (8).
  • the transition curves (2) were opened in slots with an electric hammer equipped with chisel.
  • the following steps were followed in the process for the implementation of the strengthening system: treating and cleaning the bonding surface; applying the adherence agent in a uniform layer over the surface; and applying the strengthening reinforcement pressing it down slightly to ensure contact between the strengthening reinforcement and the adherence agent.
  • the following steps were followed in the application of the strengthening system: marking the grooves on the surface; opening and cleaning the grooves; filling approximately half the depth of the grooves with adherence agent; applying the strengthening reinforcement on the adherence agent; and filling the grooves completely.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Reinforcement Elements For Buildings (AREA)
  • Working Measures On Existing Buildindgs (AREA)
EP15754011.3A 2014-07-09 2015-07-09 Strukturelles verstärkungssystem mit intern durch haftung verankerten verstärkungen Withdrawn EP3168384A1 (de)

Applications Claiming Priority (2)

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PT10775514 2014-07-09
PCT/IB2015/055208 WO2016005941A1 (pt) 2014-07-09 2015-07-09 Sistema de reforço estrutural com armaduras ancoradas internamente por aderência

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EP3168384A1 true EP3168384A1 (de) 2017-05-17

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CN111395328A (zh) * 2020-04-22 2020-07-10 台州学院 混凝土桩耐久性修补模块
CN111608418A (zh) * 2020-05-26 2020-09-01 华中科技大学 一种带新型嵌入式锚固装置的frp筋及其应用方法
WO2020234341A1 (fr) * 2019-05-23 2020-11-26 Soletanche Freyssinet Procédé de renforcement d'une structure
EP3318690B1 (de) * 2015-06-30 2022-08-24 Clever Reinforcement Iberica- Materiais De Construçao Lda. Kohlenfaserverstärkungspolymer und seine respektive anwendungstechnik für die verstärkung von betonstrukturen

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CN107724232A (zh) * 2017-10-30 2018-02-23 安徽省交通控股集团有限公司 一种用于局部混凝土连接的应力缓解构造

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3318690B1 (de) * 2015-06-30 2022-08-24 Clever Reinforcement Iberica- Materiais De Construçao Lda. Kohlenfaserverstärkungspolymer und seine respektive anwendungstechnik für die verstärkung von betonstrukturen
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CN111395328A (zh) * 2020-04-22 2020-07-10 台州学院 混凝土桩耐久性修补模块
CN111395328B (zh) * 2020-04-22 2021-04-06 台州学院 混凝土桩耐久性修补模块
CN111608418A (zh) * 2020-05-26 2020-09-01 华中科技大学 一种带新型嵌入式锚固装置的frp筋及其应用方法
CN111608418B (zh) * 2020-05-26 2021-08-03 华中科技大学 一种带嵌入式锚固装置的frp筋及其应用方法

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