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EP 0 371 983 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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09.09.1992 Bulletin 1992/37 |
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Date of filing: 01.07.1988 |
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International Patent Classification (IPC)5: E04C 5/06 |
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International application number: |
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PCT/SE8800/366 |
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International publication number: |
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WO 8900/226 (12.01.1989 Gazette 1989/02) |
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LATTICE GIRDER
GITTERTRÄGER
POUTRE EN TREILLIS
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Designated Contracting States: |
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AT BE CH DE FR GB IT LI LU NL SE |
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Priority: |
03.07.1987 SE 8702756
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Date of publication of application: |
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13.06.1990 Bulletin 1990/24 |
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Proprietor: FUNDIA BYGG AB |
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S-301 03 Halmstad (SE) |
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Inventors: |
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- SUNDMAN, Bengt
S-777 00 Smedjebacken (SE)
- BERGE, Olav
S-430 40 Särö (SE)
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Representative: Ellner, Lars O. et al |
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AWAPATENT AB,
Box 45086 104 30 Stockholm 104 30 Stockholm (SE) |
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References cited: :
AT-B- 293 697 DE-B- 1 269 324 US-A- 1 740 493
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DE-A- 2 034 034 DE-C- 200 025
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] The present invention relates to a lattice girder for reinforcing sandwich panels
and like structures of concrete, comprising longitudinal wires extending in parallel
on different levels, and zigzag wire stirrups interconnecting said longitudinal wires.
[0002] The tensile strength of concrete is low as compared to its compressive strength.
Hence, where tensile stress occurs in concrete structures, use is frequently made
of steel rods to increase the load capacity of the structures.
[0003] Tensile stress occurs at many different points in concrete structures, and for a
variety of reasons. To achieve the intended function in the structures, certain parts
of the reinforcement are frequently embraced by closed stirrups, or different structural
parts are joined by means of half-open stirrups. In concrete engineering, different
techniques have developed for providing the embracing transverse reinforcement which
is so important to the structures, involving the use of e.g. transverse force stirrups,
stirrups in the anchor zone, embracing reinforcements in compressed structural members
or in the transition zone between the web and flanges in T and I girders or columns.
[0004] The embracing stirrups are manufactured from steel rods having the desired size and
cross-sectional area, by bending. The stirrups are mounted to embrace the longitudinal
rods and are attached thereto by a thin steel wire (tying wire). The purpose of such
connection (tying) is to ensure that the reinforcement rods will be correctly positioned
in both longitudinal and transverse direction. The so-called reinforcement cage thus
formed is frequently manufactured separately from the concrete structure and is then
positioned in the form and fixed therein. A characteristic feature of the tying wire
connection is that the wire is not intended to transmit tensile stress in the structure.
[0005] In recent years, reinforcement cages have also been prefabricated in which the stirrups
have been fixed in position by spot welds between the longitudinal and transverse
rods.
[0006] One possibility of combining transverse reinforcement and reinforcement against deflection,
while simultaneously improving the function of the reinforcement in the concrete structure,
is to employ the welded lattice girders which have been patented for use in lightweight
concrete (Swedish patent 7506l73-9).
[0007] The present invention relates to a lattice girder which can be connected with prefabricated
reinforcement units such as further lattice girders or welded mesh reinforcements,
without using a tying wire, thereby to interconnect at the same time a large number
of reinforcement rods in their correct position so that a coherent unit is formed.
The separate reinforcement units extend in parallel with the longitudinal rods which
they are intended to interconnect. The design of the individual reinforcement units
facilitates such connection and renders it possible to transmit tensile stress in
the finished structure.
[0008] The invention provides for considerable time saving in reinforcement work. Reinforcement
cages can be manufactured in a fraction of the time required today for tying stirrups
to longitudinal rods in conventional manner.
[0009] Compared to welding of the stirrups to the longitudinal rods, the connection according
to the present invention can be made without large investments in welding equipment.
[0010] The connection is made by means of a lattice girder comprising three longitudinal
steel rods and two zigzag wires, alternatively a lattice girder having two or four
longitudinal wires and one zigzag wire which is positioned on one side of the longitudinal
wires, or two zigzag wires positioned each on one side of the longitudinal wires so
as to be symmetrical for force-absorbing purposes. The lattice girder as described
can be triangular in shape or extend in one plane. Such a lattice girder is disclosed
in AT-B-293 697, for example.
[0011] The inventive lattice girder is characterised in that the zigzag wires interconnecting
the longitudinal wires are formed as loops outside the longitudinal wires. The loops
are cut open adjacent to the longitudinal wires such that a transverse wire or rod
can be inserted into the groove or be positioned in the loop by being turned.
[0012] The lattice girder is attached by means of the loops to welded mesh reinforcements
of varying width and shape, or to further reinforcement girders such that the connection
is triangular, square or rectangular in section. This design provides for a reinforcement
which, in concrete structures, is capable of absorbing tensile stress in the concrete
and which functions as an embracing reinforcement, the different members forming the
connection in the structure. Consequently, large reinforcement structures can be produced
with great accuracy and in a very short time. The reinforcement structure is rigid
and can be transported as a unit, which facilitates handling on the building site.
It is further capable of absorbing the torsional stress occurring in concrete structure
elements when these elements are lifted or subjected to loads in the final structure.
[0013] The invention will now be described in greater detail below, reference being had
to the accompanying drawing in which:
Fig. l is a perspective view of a lattice girder designed according to the present
invention,
Fig. 2 illustrates schematically alternative embodiments of the lattice girder, and
Figs. 3-5 illustrate schematically various applications of the lattice girder according
to the invention.
[0014] Fig. l is a perspective view of a lattice girder comprising three longitudinal wires
l which are interconnected by means of zigzag wire stirrups 2 to form a lattice girder
having a triangular section. The wire stirrups 2 extend slightly beyond the respective
longitudinal wire l, such that loops 3 are formed outside said wire. On one side,
the loops 3 are cut open adjacent to the longitudinal wire l so as to form a groove
4 into which a transverse wire 5 can be inserted. As shown in the lower left part
of Fig. l, the loops 3 of neighbouring stirrups can be cut open in parallel with each
other or, as shown to the right, they can be oppositely cut open so that the transverse
wire 5 can be inserted into the grooves 4 by being turned. The wire 5 may be a single
wire interconnecting several lattice girders, or it can be a wire in a mesh reinforcement
or some other prefabricated reinforcement unit.
[0015] Fig. 2 shows alternative embodiments of the lattice girder which may thus comprise
two or four longitudinal wires l and a zigzag wire stirrup 2 extending on one side
of the longitudinal wires l, or between pairs of longitudinal wires, as shown in the
upper part of Fig. 2, viz. to the left a cross-section of the lattice girder and to
the right a side view thereof. The lower part of Fig. 2 illustrates a further variant
of the lattice girder with two longitudinal wires l and wire stirrups 2 extending
on both sides thereof, as shown to the left. The wire stirrup 2 can be arranged in
parallel with each other, as shown in the lower center part of the Figure, or can
be relatively offset, as shown in the lower right part of the Figure.
[0016] Figs. 3-5 show how a lattice girder according to one of the embodiments above can
be used for reinforcing a structural member of concrete.
[0017] The lattice girders exemplified above can, of course, be modified in different ways.
Thus, the wire stirrups may be extended to form loops merely on one side of the lattice
girder. Moreover, not all of the loops need be cut open to form grooves. The invention
is therefore not limited to the embodiments described above and shown in the drawing,
but can be modified within the scope of the appended claims.
l. A lattice girder for reinforcing sandwich panels and like structures of concrete,
comprising longitudinal wires (l) extending in parallel on different levels, and zigzag
stirrups (2) interconnecting said longitudinal wires, characterised in that said wire stirrups (2) extend, at least on one side, beyond the respective
longitudinal wire (l) so as to form loops (3) outside said wire, and that at least
some of the loops (3) are cut open adjacent said longitudinal wire (l) to form grooves
(4) into which transverse wires (5) are insertable to connect said lattice girder
with other reinforcement units.
2. A lattice girder as claimed in claim l, comprising two parallel wire stirrups (2)
extending each on one side of said longitudinal wires (l), characterised in that the loops (3) of said wire stirrups are cut open in parallel with each other
such that said longitudinal wires (5) are insertable into said grooves (4) from one
side.
3. A lattice girder as claimed in claim l, comprising two parallel wire stirrups (2)
extending each on one side of said longitudinal wires, characterised in that the loops (3) of said wire stirrups are oppositely cut open so that said
longitudinal wires (5) are insertable into the grooves by being turned.
4. A lattice girder as claimed in any one of the preceding claims, characterised in that said wire stirrups (2) form loops (3) on both sides of said lattice girder.
1. Gitterträger zum Armieren von Verbundplatten oder ähnlichen Strukturen aus Beton mit
longitudinalen Drähten (1), die sich parallel auf verschiedenen Ebenen erstrecken,
und mit zickzackförmigen Bügeln (2), die die longitudinalen Drähte verbinden, dadurch
gekennzeichnet, daß die Drahtbügel (2) sich auf wenigstens einer Seite über den jeweiligen
longitudinalen Draht (1) hinaus erstrecken, so daß sie Schleifen (3) außerhalb des
Drahtes bilden, und daß wenigstens einige dieser Schleifen (3) neben dem longitudinalen
Draht (1) aufgeschnitten sind, um Vertiefungen (4) zu bilden, in die transversale
Drähte (5) einsetzbar sind, um den Gitterträger mit anderen Armierungseinheiten zu
verbinden.
2. Gitterträger nach Anspruch 1, mit zwei parallelen Bügeln (2), die sich jeweils auf
einer Seite der horizontalen Drähte (1) erstrecken, dadurch gekennzeichnet, daß die
Schleifen (3) der Drahtbügel parallel zueinander aufgeschnitten sind, so daß die longitudinalen
Drähte (5) in die Vertiefungen (4) von einer Seite aus einsetzbar sind.
3. Gitterträger nach Anspruch 1, mit zwei parallelen Bügeln (2), die sich jeweils auf
einer Seite der horizontalen Drähte (1) erstrecken, dadurch gekennzeichnet, daß die
Schleifen (3) der Drahtbügel einander gegenüber aufgeschnitten sind, so daß die longitudinalen
Drähte (5) in die Vertiefungen (4) einsetzbar sind, indem sie gedreht werden.
4. Gitterträger nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß
die Drahtbügel (2) Schleifen (3) auf beiden Seiten des Gitterträgers bilden.
l. Poutre en treillis destinée à renforcer des panneaux sandwich ou structures analogues
en béton, comprenant des barres longitudinales (l) qui s'étendent parallèlement à
différents niveaux et des étriers en zig-zag (2) qui interconnectent lesdites barres
longitudinales, caractérisée en ce que lesdits étriers (2) en barre se prolongent,
au moins sur un côté, au-delà de la barre longitudinale (l) respective, de manière
à former des boucles (3) en dehors de ladite barre et en ce qu'au moins certaines
des boucles (3) sont coupées et ainsi ouvertes dans la région adjacente à ladite barre
longitudinale (l) pour former des encoches (4) dans lesquelles on peut enfiler des
barres transversales (5) pour assembler ladite poutre en treillis à d'autres unités
d'armature.
2. Poutre en treillis selon la revendication l, comprenant deux étriers parallèles
en barre (2) qui s'étendent respectivement sur les deux côtés desdites barres longitudinales
(l), caractérisée en ce que les boucles (3) desdits étriers en barre sont coupées
et ainsi ouvertes parallèlement entre elles de manière qu'on puisse enfiler lesdites
barres longitudinales (5) dans lesdites encoches (4) par un côté.
3. Poutre en treillis selon la revendication l, comprenant deux étriers parallèles
en barre (2) qui s'étendent respectivement sur les deux côtés desdites barres longitudinales,
caractérisée en ce que les boucles (3) desdits étriers en barre sont coupées et ainsi
ouvertes l'une à l'opposé de l'autre, de manière qu'on puisse enfiler lesdites barres
longitudinales (5) dans les encoches en les tournant.
4. Poutre en treillis selon une quelconque des revendications précédentes, caractérisée
en ce que lesdits étriers en barre (2) forment des boucles (3) sur les deux côtés
de ladite poutre en treillis.