Classifications

• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
  • E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
  • E04C5/01—Reinforcing elements of metal, e.g. with non-structural coatings
  • E04C5/06—Reinforcing elements of metal, e.g. with non-structural coatings of high bending resistance, i.e. of essentially three-dimensional extent, e.g. lattice girders
  • E04C5/0645—Shear reinforcements, e.g. shearheads for floor slabs

Definitions

• the present invention relates to a reinforcing element for structural concrete construction, in particular for reinforced or prestressed concrete construction, comprising a rod-shaped bar having a cross-sectional enlargement on at least one end thereof.
• the method for producing the reinforcing element and the corresponding reinforced structural concrete construction are also provided.
• the bars require sufficient concrete cover to avoid rusting and corrosion problems. Typical values for this cover lay between 35 to 50 mm. Moreover, a minimum embedment length (or development length) has to be provided so that the reinforcement can develop its yield strength. Typical values for this length in ordinary concrete lay between 35 to 40 times the diameter of the bar.
• a reinforcing element for concrete construction in the form of a set bolt is formed of a rod-shaped section with a cross-sectional enlargement provided on the end.
• the cross-sectional enlargement is formed of glass-fibre reinforced plastic and has an axial bore in its centre.
• the cross-sectional enlargement is provided as a separate part engaged in a form-locking manner with the rod-shaped section of the set bolt.
• the two components are connected by gluing, screwing, fusing, etc.
• the bar and bolts always lay inside the concrete.
• the disclosed embodiments do not allow introducing intermediate pieces as suspension points and the significant size of the bolts does not allow using them in all types of configuration, such as for instance thin slabs.
• Shearing force reinforced structure and member discloses the use of a link member to reinforce an existing concrete member.
• the document discloses a shearing force reinforced structure for an existing reinforced concrete structure body.
• the structure is configured with a side wall of an existing reinforced concrete structure, shearing force reinforced members arranged inside reinforced member insertion holes with bottoms formed in a direction intersecting a major reinforcing bar of the side wall. Fillers are provided in the holes.
• Each of the shearing force reinforced members is configured with a shearing force reinforcing bar, a plate head and a ring head respectively fixed at a base end and top end of the reinforcing bar. This technique is exclusively to be post-installed by boring holes in an existing member.
• WO 02/48476 relates to the integration of bundles of reinforcing fibres in a curable material such as concrete.
• the proposed solution consists in preparing bundles of reinforcing fibres, the fibres of a bundle being joined at the ends thereof by means of an adhering substance that loses its cohesion under the influence of mechanical forces during the mixing of the reinforcement bundles with the curable material.
• the adhering substance comprises a material which is substantially inert with respect to the non-cured curable material.
• curable material comprising reinforcing fibres that are no longer joined, but are spread separately in the curable material after mixing.
• Said fibres provide protection in all directions against cracking, but do not provide a specific reinforcement along a specific direction. Said fibers are therefore quite different from and not comparable with reinforcing bars usually used in reinforced concrete.
• a reinforcing element for structural concrete construction in particular for reinforced or prestressed concrete construction, comprising:
• This reinforcing element provides a single solution in order to solve at the same time the problems of minimum concrete cover, spalling of the concrete cover and development length.
• the reinforcing element involves a rod-shaped bar, that is to say an elongated reinforcing component that is oriented in a specific reinforcement direction, and that is not mixed with the curable material for instance like the fibres of WO 02/48476, but preliminary placed in a determined position within the formwork before the concrete is casted, as usual in reinforced concrete.
• a rod-shaped bar features a much longer length and diameter (for instance 15 to 25 cm long or even up to 50 cm in certain cases where the concrete construction is substantially thick, and about 10 to 12 mm diameter) than fibres of WO 02/48476 (for instance about 2 to 3 cm long and about 100 ⁇ m diameter).
• the protection block material is concrete and preferably high or ultra high performance concrete.
• the protection block material is selected from the list comprising ceramic, resin. Any of the above mentioned materials may be reinforced with fibers.
• the protection block is preferably disk-shaped, but several variants, such as parallelepiped shapes may also be provided.
• the protection block material is substantially impermeable (watertight).
• at least the outer portion of said protection block is provided with a substantially low permeability of low porosity material.
• the protection block material provides high adhesion to said rod-shaped bar. Optimization of embedment length may be obtained if the protection block surface interfacing with said rod-shaped bar provides a substantially high adhesion to the rod-shaped bar.
• the reinforcing element comprises two protection blocks, one at each end thereof.
• the rod-shaped bar is U-shaped with a connecting leg provided between the two axial portions and further comprises a protection block in which said connecting leg is at least partially embedded.
• the reinforcing element is further provided with a protection channel provided on one axial portion of the rod-shaped bar, at the immediate proximity of said protection block. Such a channel may be helpful to provide extended impermeability along the main portion.
• the elbow portion comprises an angled portion and a radial member extending substantially radially from adjacent axial portion.
• the angle between the radial member and adjacent axial portion is substantially 90 degrees.
• Other values can be considered to enhance bond performance, in particular angles lower than 90 degrees.
• the invention also provides a method for producing a reinforcing element for structural concrete construction in the form of a rod-shaped bar provided with a protection block at one end thereof, comprising the steps of producing said rod- shaped bar, bending end portion of said rod bar, covering said bent portion with a protection block.
• the protection block may be provided by molding or by spraying.
• the invention further provides a reinforced structural concrete construction, comprising:
• a rod-shaped bar comprising an elbow portion on said at least one end, said elbow portion being embedded in a protection block;
• said rod-shaped bar being at least partially embedded in said concrete volume according to a given reinforcing position in which said protection bloc is also at least partially embedded in said concrete volume in order to provide said reinforced concrete construction.
• the protection bloc is fully embedded in said concrete volume.
• - Figure 1 c shows spalling cracks on the compression face of a structural concrete member
• - Figure 1d presents a conventional T-headed bar and the corresponding concrete cover
• - Figure 2a is a schematic representation of a reinforcing member in accordance with the invention.
• Figure 2b is a first variant of the reinforcing member of figure 2a;
• - Figure 2c is a schematic representation of a second embodiment of the reinforcing member of the invention.
• Figures 1 a to 1 d illustrates known type reinforcements embedded in concrete constructions.
• the reinforcement 1 is configured such as to provide a concrete cover having a minimum thickness CC1.
• the bars require sufficient concrete cover to avoid rusting and corrosion problems. Typical values for this cover lay between 35 to 50 mm.
• the concrete cover is arranged such as to provide a minimum thickness CC1 between known type T-headed bar reinforcement and the concrete surface, for the same reasons as above.
• Figure 1 b shows the development length DL1 required in a known type installation.
• the bar shall be embedded in the concrete.
• DL1 may require significant embedment length. Depending on the specific construction configuration, such a length may sometimes not be provided.
• Figure 1 c illustrates the problem of cover spalling, after spalling cracks 22 have appeared in the reinforced concrete of prior art installations.
• Figures 2a to 2d illustrate various embodiments of a reinforcing element 10 according to the invention.
• the reinforcing element 10 is provided with an extended rod-shape bar 1 1.
• This rod-shaped bar is preferably made with steel alloys.
• the axial portion 16 of the rod-shaped bar 1 1 is substantially elongated, and generally substantially linear.
• the length of the rod- shape bar may vary depending on the type of application, the required reinforcement level and the concrete construction thickness. For instance, in typical structural concrete constructions, the length is substantially between 15 to 30 cm, or more in certain cases. For instance, in specific applications, the length may reach up to about 50 cm. Other dimensions are also possible without departing from the invention.
• rod- shaped bar also includes wires and strands, for instance, similar to those used in prestressed concrete.
• Rod-shaped bars generally feature diameters substantially between 10 to 12 mm.
• Wires and strands generally have diameters substantially between 5 to 6 mm.
• At least one end of the rod-shaped bar is provided with an elbow portion 12, having an angled portion 13 joining the axial portion 16 to a radial portion 14.
• the angle ⁇ between radial member 14 and adjacent axial portion 16 is substantially 90 degrees. Angles near 90 degrees provide high anchoring force between the rod-shaped bar and the block. Other angle values may be provided depending on the mechanical requirements of the construction work.
• the length of the axial and radial portions 16 and 14 depends on the application in which the reinforcing member shall be used. More particularly, the length of the radial portion 14 is defined as a function of the global resistance to be provided in the planned construction. For more convenience and in order to reduce manufacturing costs of the reinforcing elements 10, the most usual standard dimensions may be provided on a large scale manufacturing basis.
• the elbow portion 12 is embedded in a protection block 15.
• This protection block provides a very efficient protection against corrosion and rusting of the rod- shaped bar 1 1. It also contributes to reduce the required embedment length.
• the block 15 is preferably made with a material having low porosity or permeability. The material is to be such that protection to corrosion, considering the bar cover within the block (typically equal to the diameter of the bar), is the same as the protection with ordinary cover in traditional reinforced concrete members.
• the block 15 may be made with concrete, preferably high or ultra-high performance concrete or similar cementitious materials, preferably reinforced with fibers, such as Ductal, a well known UHPFRC (Ultra High Performance Fiber Reinforced Concrete).
• the block 15 may also be made with other materials, such as ceramic, resin or synthetic material.
• the selected material should also preferably provide high adherence between the material and the rod-shaped bar 1 1.
• Typical average values of bond strength measured in standard pull-out tests lay between 40 to 60 MPa.
• a block 15 comprises two materials, one for the outer surfaces, having very low permeability, and one for the inner volume of the block, offering less permeability protection, but allowing producing at lower global costs.
• the material providing the interfacing surface with the rod-shaped bar 1 1 is specifically selected to provide high adherence with the latter.
• the protection block 15 shape or profile may vary depending on the type of use, the mechanical properties, manufacturing costs, etc.
• the blocks 15 have disk profiles. Other profiles such as parallelepiped may also be used.
• the block dimensions are determined in order to optimize the global mechanical properties of the construction work using the reinforcing elements. For best results, a minimum thickness of material covering the elbow portion 12 is provided.
• the elbow portions 12 are fully embedded in the blocks 15.
• a protection block may entirely or partly embed the radial portion 14 only, while the angled portion 13 is not embedded. This would allow protecting the reduced embedded area against rusting and corrosion.
• Figure 2b shows a variant of the embodiment of Figure 2a in which two protection blocks 15 are provided, one at each end, in an arrangement similar to the previously described arrangement of Figure 2a, involving elbow portions 12 imbedded in protection blocks 15 at both ends of the reinforcing element 10.
• Figure 2c and Figure 2d illustrate embodiments with U-shaped reinforcing elements 10 in which two axial portions 16 are provided on each side of a connecting leg 17.
• the connecting leg 17 is not covered or embedded. Both free ends of the axial portions 16 are provided with embedded elbow arrangement similar to the previously described arrangement in relation with Figure 2a.
• the embodiment of Figure 2d differs from the latter in that the connecting leg 17 is at least partially embedded in a protection block 15. In the example shown in Figure 2d, the connecting leg 17 is entirely embedded.
• the rod-shaped bars 1 1 to be used can either be ordinary or high-strength reinforcing bars or pre-stressing bars or tendons to be fully or partly embedded in structural concrete members where at least one end is embedded in a protection block 15.
• Figure 3 presents a comparison between the standard concrete cover required minimal thickness CC1 and minimal concrete cover CC2 resulting from the invention.
• the protection block of the reinforcement element may be placed into the CC1 zone of prior art installations, thus reducing considerably the concrete cover minimal thickness.
• Figure 4 depicts a comparison between the standard embedment length required DL1 and embedment length DL2 resulting from the invention.
• the use of an elbow portion 15 embedded in a protection block allows to significantly reduce the embedment length from DL1 (prior art configuration) to DL2.
• Typical values of DL2 lay between 10% and 15% of DL1
• the reinforcing element 10 can be used as a high performance shear and punching shear reinforcing system.
• the figures show that the compression face of the slab is suitably confined and that all reinforcements are suitably developed.
• U-shaped reinforcing elements are used.
• An example of punching shear crack 21 is provided in the Figure.
• U-shaped reinforcing elements in which the connecting legs 17 are provided with protection blocks are used.
• inclined reinforcements can also be used.
• Figure 7 shows a further application in which the confinement reinforcement for members cast with brittle (high strength or lightweight) concrete.
• the struts developing close to the compression face are suitably confined and premature spalling of the piece is avoided. Examples of cover spalling crack 22 are provided in the Figure.
• the protection blocks 15 are not embedded in the concrete. Protection channels 20 are provided adjacent to protection blocks and provide further corrosion protection.
• the protection channels 20 are preferably made with the same material as the blocks. In such a case, they may be molded together with the blocks during manufacturing. Partial embedment of the blocks is also possible.
• Figure 8 illustrates an application in which a reinforcing element 10 is used to provide anchorage points for structural concrete members.
• the reinforcing element configuration is designed to leave a portion of the element outside the structural concrete member, allowing using the free portion as tension anchorage reinforcement.
• a protection block 15 is provided to protect the rod-shaped bar 1 1 in order not to leave it in direct contact with the outer atmosphere.
• Figure 9 shows that the reinforcing element 10 may further be used as a link member to connect two parts of a structural concrete member cast at different ages or two different concrete members 40 and 41.
• the reinforcing elements of the present invention can be used in structural concrete construction in combination with the use of fibres, as for example those described in WO 02/48476, which are spread into the concrete before cast of said concrete.

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• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Reinforcement Elements For Buildings (AREA)
• Lining And Supports For Tunnels (AREA)

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Applications Claiming Priority (2)

Publications (1)

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• 2009
  • 2009-04-06 EP EP09157384A patent/EP2239391A1/en not_active Withdrawn
• 2010
  • 2010-04-06 PL PL10714089T patent/PL2417310T3/pl unknown
  • 2010-04-06 EP EP10714089A patent/EP2417310B1/en not_active Not-in-force
  • 2010-04-06 WO PCT/IB2010/051483 patent/WO2010116323A1/en active Application Filing
  • 2010-04-06 US US13/262,937 patent/US20120066988A1/en not_active Abandoned

Patent Citations (5)

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