EP0344505B1 - Wooden coffering girder - Google Patents

Wooden coffering girder Download PDF

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Publication number
EP0344505B1
EP0344505B1 EP89108677A EP89108677A EP0344505B1 EP 0344505 B1 EP0344505 B1 EP 0344505B1 EP 89108677 A EP89108677 A EP 89108677A EP 89108677 A EP89108677 A EP 89108677A EP 0344505 B1 EP0344505 B1 EP 0344505B1
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EP
European Patent Office
Prior art keywords
web
groove
grooves
spreading
strip
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EP89108677A
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German (de)
French (fr)
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EP0344505A1 (en
Inventor
Herbert Vogel
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Individual
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Individual
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Priority to AT89108677T priority Critical patent/ATE70584T1/en
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    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
    • E04C3/12—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members
    • E04C3/14—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members with substantially solid, i.e. unapertured, web
    • 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
    • E04G11/00—Forms, shutterings, or falsework for making walls, floors, ceilings, or roofs
    • E04G11/36—Forms, shutterings, or falsework for making walls, floors, ceilings, or roofs for floors, ceilings, or roofs of plane or curved surfaces end formpanels for floor shutterings
    • E04G11/48—Supporting structures for shutterings or frames for floors or roofs
    • E04G11/50—Girders, beams, or the like as supporting members for forms

Definitions

  • the invention relates to a wooden or formwork girder with two spars which are spaced apart by a web, the spars on the mutually facing sides having approximately dovetail-shaped grooves in cross section and the web on its narrow sides insertable into these grooves having at least one slit-shaped recess, which in the use position in the interior of the dovetail-shaped grooves by a bar or the like that penetrates into the slot when inserted into the slots, tapers in cross-section tapering towards the inside of the slot and can thereby be positively fixed within the dovetail-shaped groove, preferably the contact areas between the grooves of the spars and the web are sealed with glue or the like.
  • Such a wooden support is known from FR-A-2373654 with the restriction that the bar used for spreading out does not consist of wood but of metal.
  • this strip is T-shaped in cross-section and is attached with its widened flange to the bottom of the groove within the spar with anchoring tips.
  • the spreader bar thus forms a fixed and immovable part of these spars before the final assembly of the web within the spars.
  • This gives rise to the problem that the different materials react differently in the case of thermal expansions and thus tensions from this strip and its Anchoring can be transferred to the spar.
  • the penetration of the anchoring tips into the wooden spar can have a splitting effect on this spar and thus weaken it.
  • a comparable carrier is shown in DE-PS 3210928, the web to be inserted between the spars being of two-shell construction and being held together only in its central region, so that the spaced-apart webs can spring apart well in the edge regions.
  • the parts that spring apart are conical in cross-section and taper towards the edges, while the corresponding two grooves in the spars have corresponding shapes.
  • the spreader bar which is provided in one piece on the spar, has a relatively large thickness, but nevertheless cannot prevent the parts from becoming detached again if the gluing is faulty or has not yet set. Furthermore, the special shape on the edges of the web on the one hand and on the spars on the other hand must be regarded as complex.
  • the spreading strip is a separate part that can be moved within the groove or at the bottom of the groove, independently of the spar web. If the web with its slit-shaped recesses is pressed into the dovetail-shaped groove of the spar and pushed onto the spreader bar striking the base of the groove, it is not only deformed accordingly in the form of a dovetail, but is also jammed with the spreader bar due to the spreading forces and the deformation.
  • a further possible embodiment of the invention of considerable importance or of its own worthy of protection may consist in the spreading strip being made of other materials in particular harder material than the spar, preferably made of hardwood, plastic or the like.
  • Non-shrinking and / or non-swelling material This is not possible with a spreader bar made in one piece with the spar, if the entire spar is not to be made of such an expensive and complex material.
  • the spar can be made of inexpensive and, under certain circumstances, softer material and still secure and good jamming can be achieved with the spreader bar, without this changing its properties over time and thus its holding function that supports the gluing well.
  • such a wooden formwork beam can be removed from a tensioning device much earlier in its manufacture than such a beam, in which the gluing must first harden or dry, since the separate spreading strip generates a sufficiently good holding force from the outset in order to to allow the glue to set and harden securely even when the beam is stretched out. This means that production can be accelerated and made cheaper.
  • the height of the wedge-shaped cross-section corresponds to the depth of the front slots of the webs and at the same time at least the depth of the dovetail-shaped groove of the bars.
  • the spreader bar extends over the entire insertion depth of the groove, so that even the slightest tensile forces at the narrow entry opening of the groove lead to self-jamming. This could be reinforced if the wedge-shaped spreader bar were even slightly higher than the groove.
  • Another embodiment of the invention of its own worthy of protection which improves and simplifies the connection between the web and the spar and the risk of Blowing up of the web considerably reduced or even switched off by the spreader bar can consist in the fact that the edges of the webs have at least two parallel slots and a spreader bar is provided for each slot, which can be used separately and independently of the spar in these.
  • the spreading of the web edges serving to fill the dovetail-shaped groove cross-section is thus distributed over two slots, so that each slot has to be expanded less, but a corresponding cross-sectional enlargement of the slot and adaptation to the groove cross-sectional shape is nevertheless achieved.
  • two spreading strips for two adjacent edge slots at the transition from the facing flat sides to the narrow sides located in the use position on the groove base of the spars each have a right angle and the outer flat sides are inclined obliquely in a wedge shape at an acute angle . This results in a targeted spreading of the outer layers of the plate forming the web, while the area of this plate located between the two slots forms a uniform abutment over the entire cross-sectional height of the wedge-shaped strip.
  • a good adaptation of the surface areas of the webs located in the groove results if the sides of the spreading strip (s) facing the side walls of the dovetail groove correspond to the negative bevel of this groove wall.
  • the bridge of this wooden formwork or wooden beam can be made of Glulam is made of wood, the surfaces of the individual wood layers running parallel to the top of the web and the edge slots for the spreading strips can extend parallel to these wood layers. This results in an inexpensive manufacture of the webs, but the individual layers can still be prevented from bursting open if the spreading forces and spreading movements are each distributed over two parallel slots.
  • the spreads of the edges of the webs can thereby be kept small and yet the transmissible forces can be large if the angle of the cross section of the oblique side surface (s) of the wedge-shaped strip relative to the direction of insertion or to a perpendicular to the base of the groove is so pointed or small that in the event of a tensile load on the web from the groove between the strip and the edge slot in the outwardly narrowing groove there is an automatically increasing clamping force.
  • Such a clamping force results from the clamping of the spreading strip when spreading the or the edge-side slots of the webs, but the slot area of the web could slip off such a wedge again if the angle is too large. This can be ruled out by means of a correspondingly narrow angle, which at the same time also keeps the spreading forces low.
  • the angle of the cross section of the dovetail-shaped groove between the base of the groove and the side wall - and thus also the corresponding wedge angle of the expansion bar - can be approximately 80 to 89 °, preferably approximately 84 °, 85 ° or 86 °.
  • a combination of the features and measures described above results in a wooden girder, in which the bars with the spars are pressed immediately after pressing due to the separate spreading strips, corresponding clamps are produced so that an additionally provided gluing can harden and set without permanent clamping and pressing. If necessary, gluing can even be completely dispensed with.
  • a subsequent deterioration of the connection due to a shrinkage of the spreader bar or swelling, which could lead to a cracking of the groove and thus also to a loosening of the connection, can be avoided in that the spreader bars are separate parts that can have corresponding material properties.
  • a wooden formwork beam 1 each shown in FIGS. 2 and 4 with a cross-sectional half has two spars 3 which are spaced apart by a web 2, one of which is shown in each case.
  • the crosspieces of the spars 3 each have an approximately dovetail-shaped groove 4 on the sides 3a facing one another, which can be seen particularly clearly in FIGS. 1 and 3.
  • the web 2 has on its narrow sides 2a insertable into these grooves 4 according to FIGS. 1 and 2 one, according to FIGS.
  • two slit-shaped recesses 5, which in the use position inside the dovetail-shaped grooves 4 by inserting into the grooves 4 in the slot 5 penetrating, in cross-section tapering to the interior of the slot 5 spreading bar 6 can be spread and thereby can be fixed in a form-fitting manner within the dovetail-shaped groove 4 according to FIGS. 2 and 4.
  • the narrow side 2a of the web 2 initially corresponds in its cross-sectional thickness to the width of the groove 4 at its entry on the upper side 3a of the spar 3, in the use position but then, due to the expansion bar 6 pressed into the slot 5, it has a considerably enlarged dimension, which fills the dovetail-shaped groove 4 and thus produces a positive connection.
  • the contact areas between the walls of the groove 4 of the spars 3 and the web 2 can additionally be sealed with glue in a manner not shown, and this connection can also be improved as a result.
  • the spreading strip 6 is a separate part which can be used independently of the spar 3 and the web 2. This is particularly evident in FIGS. 1 and 3. This results in jamming this spreader bar 6 within the slots 5, so that with a tensile force on the web 2 out of the spar 3, the desired resistance to a solution of such a connection is given, while in a spreader bar integrally connected to the spar 3 on the base of the groove, the two on both sides of the Slot 5 located leg of the web 2 could slip out of this groove again.
  • the spreading bar 6 can be made of harder and more resistant material than the spar, e.g. made of hardwood, plastic or another non-shrinking and / or non-swelling material. This results in a long-lasting connection that cannot be loosened by wetness or dryness, even if the gluing was absent or faulty or had weakened.
  • the height of the wedge-shaped cross-section strips 6 corresponds to the depth of the front slots 5 of the webs 2 on the one hand and on the other hand the depth of the dovetail grooves 4 of the spars 3. This ensures that the edges of the webs are spread apart 2 runs over the entire height of the groove. At the same time, the narrow insertion opening of the groove 4 also ensures that the web 2 is not blown open by the wedge-shaped strips 6.
  • the two spreading strips 6 for two adjacent edge slots 5 each have a right angle at the transition from the mutually facing flat sides 6a to the narrow sides 6b located in the use position on the groove base 4a of the spars 3; the outer flat sides 6c, however, are inclined obliquely in a wedge shape at an acute angle.
  • the area of the web 2 located between the two slots 5 is used as a full-area support over the entire groove height and is not subjected to any additional squeezing, while the web areas located on the outside of the slots 5 according to FIG. 4 are adapted to the dovetail shape of the groove 4 if the three parts are pressed together in the direction of arrow Pf1 (FIGS. 1 and 3).
  • the two expansion strips 6 of each edge connection of a web 2 with a spar 3 made of hardwood or plastic or the like can also exist in this case and lead to a permanent positive connection.
  • the angle of the cross section of the oblique side surfaces 6c of the wedge-shaped bar 6 both in the exemplary embodiment according to FIG. 3 and according to FIG. 1, which is formed with respect to the insertion direction according to arrow Pf1 or with respect to a perpendicular to the groove base 4a, is in the off exemplary embodiment so small and small that a tensile loading of the web from the groove 4 forms an increasing clamping force in the outwardly narrowing groove 4 against the arrow Pf1 between the strip 6 and the edge slot 5 in the groove 4 narrowing towards the outside, so that there is a certain self-locking or self-locking.
  • This contributes to the fact that the separate spreading strip 6 could follow this movement with such a pulling movement since it is not firmly and integrally connected to the groove and the spar, but is practically completely enclosed by the slot 5.
  • the web 2 can e.g. consist of glulam, the surfaces of the individual wood layers run parallel to the top of the web and the edge-side slots 5 for the expansion strips 6 extend parallel to these wood layers. Nevertheless, there is no fear of the individual layers being blown open by the strips 6, since the spreading practically takes place only when they are pressed into the groove and the narrowing of this groove on the upper side 3a of the spars compresses the remaining part of the webs 2.
  • the angle of the cross section of the dovetail-shaped groove 4 between the groove base 4a and the side wall is approximately 80 ° to 89 °, preferably approximately 84 °, 85 ° or 86 °.
  • parts of the web 2 penetrating into the groove 4 are spread out, for which purpose the spreading strips 6 expediently have corresponding helix angles.
  • a wooden girder preferably a wooden formwork girder 1 with two bars 3 spaced apart by a web 2, the bars 3 on the sides 3a facing one another in cross section approximately dovetail-shaped grooves 4 and the web on its narrow sides insertable into these grooves 4 2a one or two, optionally also have more slit-shaped recesses 5 which, in the use position, inside the dovetail-shaped grooves 4 by means of a strip which, when inserted into the grooves 4, penetrates into the slot 5 and can be pressed in, in cross-section tapers towards the inside of the slot 5, i.e. away from the bottom of the groove 4a 6 expandable and thereby positively fixed within the dovetail groove 4.
  • the contact areas between the grooves 4 of the bars 3 and the web 2 can be sealed with glue. It is essential that the spreading strip 6 or the spreading strips 6 are each a separate part which can be inserted and pressed in independently of the spar 3 and the web 2 and which therefore lead to self-jamming and prevent unwanted loosening movements even in the event of missing or defective gluing.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
  • Forms Removed On Construction Sites Or Auxiliary Members Thereof (AREA)
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Abstract

The girder (1) has two capping pieces (3) held apart by a web (2), the capping pieces (3) having on the sides (3a) facing each other grooves (4), which are approximately dovetailed in cross-section, and the web having on its narrow sides (2a), which can be inserted into these grooves (4), one or two, if appropriate also more, slot-shaped recesses (5) which can be spread open in the position of usage in the interior of the dovetailed grooves (4) by a strip (6), which penetrates and can be pressed into the slot (5) during insertion into the grooves (4), and tapers in cross-section towards the interior of the slot (5), that is to say away from the groove base (4a), and by this means can be fixed positively inside the dovetailed groove (4). The contact regions between the grooves (4) of the capping pieces (3) and the web (2) can be sealed with glue. The essential factor is that the spreading strip (6) or the spreading strips (6) are in each case a separate part which can be inserted and pressed in independently of the capping piece (3) and the web (2) and which thus lead to a self-clamping and avoid undesired detaching movements even when there is no glue or defective glue. <IMAGE>

Description

Die Erfindung betrifft einen Holz- oder Schalungsträger mit zwei durch einen Steg auf Abstand gehaltenen Holmen, wobei die Holme an den einander zugewandten Seiten im Querschnitt etwa schwalbenschwanzförmige Nuten und der Steg an seinen in diese Nuten einführbaren Schmalseiten wenigstens eine schlitzförmige Ausnehmung hat, die in Gebrauchsstellung im Inneren der schwalbenschwanzförmigen Nuten durch eine beim Einfügen in die Nuten in den Schlitz eindringende, im Querschnitt sich zum Inneren des Schlitzes hin verjüngende Leiste oder dergleichen aufspreizbar und dadurch formschlüssig innerhalb der schwalbenschwanzförmigen Nut festlegbar ist, wobei vorzugsweise die Berührbereiche zwischen den Nuten der Holme und dem Steg mit Leim oder dergleichen abgedichtet sind.The invention relates to a wooden or formwork girder with two spars which are spaced apart by a web, the spars on the mutually facing sides having approximately dovetail-shaped grooves in cross section and the web on its narrow sides insertable into these grooves having at least one slit-shaped recess, which in the use position in the interior of the dovetail-shaped grooves by a bar or the like that penetrates into the slot when inserted into the slots, tapers in cross-section tapering towards the inside of the slot and can thereby be positively fixed within the dovetail-shaped groove, preferably the contact areas between the grooves of the spars and the web are sealed with glue or the like.

Ein derartiger Holzträger ist aus der FR-A-2373654 bekannt mit der Einschränkung, daß die zum Aufspreizen dienende Leiste nicht aus Holz, sondern aus Metall besteht. Darüber hinaus ist diese Leiste im Querschnitt T-förmig ausgebildet und wird mit ihrem verbreiterten Flansch am Nutenboden innerhalb des Holmes mit Verankerungsspitzen befestigt. Die Spreizleiste bildet somit vor der endgültigen Montage des Steges innerhalb der Holme ein festes und unverrückbares Teil dieser Holme. Daraus ergibt sich das Problem, daß bei Wärmedehnungen die unterschiedlichen Materialien verschieden reagieren und somit Spannungen von dieser Leiste und ihrer Verankerung auf den Holm übertragen werden können. Außerdem kann das Eindringen der Verankerungsspitzen in den hölzernden Holm eine Spaltwirkung auf diesen Holm ausüben und ihn also schwächen.Such a wooden support is known from FR-A-2373654 with the restriction that the bar used for spreading out does not consist of wood but of metal. In addition, this strip is T-shaped in cross-section and is attached with its widened flange to the bottom of the groove within the spar with anchoring tips. The spreader bar thus forms a fixed and immovable part of these spars before the final assembly of the web within the spars. This gives rise to the problem that the different materials react differently in the case of thermal expansions and thus tensions from this strip and its Anchoring can be transferred to the spar. In addition, the penetration of the anchoring tips into the wooden spar can have a splitting effect on this spar and thus weaken it.

Gemäß der US-A-4195462 ist eine Lösung bekannt, bei welcher die Spreizleiste einstückig aus dem Nutengrund des Holmes hervorgeht. Beim Zusammenpressen des Steges und dieser Holme werden die seitlichen Begrenzungen der an dem Steg vorgesehenen schlitzförmigen Ausnehmungen von der Leiste auseinandergedrückt und können bei guter Verleimung eine schwalbenschwanzförmige Verbindung herstellen.According to US-A-4195462 a solution is known in which the spreader bar emerges in one piece from the groove base of the spar. When the web and these spars are pressed together, the lateral boundaries of the slot-shaped recesses provided on the web are pressed apart by the strip and, with good gluing, can produce a dovetail-shaped connection.

Versagt jedoch die Verleimung entweder unmittelbar bei der Herstellung oder im Laufe der Zeit, ergibt sich bei diesem Träger eine entsprechend leichte Lösbarkeit zwischen den für die Stabilität des Trägers eigentlich wichtigen Teilen. Darüberhinaus besteht die Gefahr, daß die Spreizleiste durch die seitlich von ihr eingeschnittenen Nuten eine verminderte Stabilität hat und insbesondere bei einer Verwendung von Holmen mit in Längsrichtung verlaufenden Fasern durch die Zwängkräfte in ihrem Querschnitt seitlich belastet und im Laufe der Zeit zusammengedrückt wird, so daß wiederum die Gefahr einer Lockerung besteht.However, if the gluing fails either directly during manufacture or over time, this support results in a correspondingly easy detachability between the parts that are actually important for the stability of the support. In addition, there is a risk that the spreader bar has a reduced stability due to the grooves cut into it laterally and, in particular when using spars with fibers running in the longitudinal direction, is laterally loaded in its cross section by the constraining forces and is compressed over time, so that again there is a risk of loosening.

Einen vergleichbaren Träger zeigt die DE-PS 3210928, wobei der zwischen die Holme einzufügende Steg zweischalig ausgebildet ist und nur in seinem Mittelbereich zusammengehalten wird, so daß die voneinander beabstandeten Stege in den Randbereichen gut auseinanderfedern können. Dabei sind diese jeweils auseinanderfedernden Teile ihrerseits im Querschnitt konisch und verjüngen sich zu den Rändern hin, während die entsprechenden beiden Nuten in den Holmen entsprechende Formen haben. Die an dem Holm einstückig vorgesehene Spreizleiste hat eine relativ große Stärke, kann aber trotzdem nicht verhindern, daß bei fehlerhafter oder noch nicht abgebundener Verleimung die Teile sich wieder voneinander lösen können. Ferner muß die spezielle Formgebung an den Rändern des Steges einerseits und an den Holmen andererseits als aufwendig angesehen werden.A comparable carrier is shown in DE-PS 3210928, the web to be inserted between the spars being of two-shell construction and being held together only in its central region, so that the spaced-apart webs can spring apart well in the edge regions. The parts that spring apart are conical in cross-section and taper towards the edges, while the corresponding two grooves in the spars have corresponding shapes. The spreader bar, which is provided in one piece on the spar, has a relatively large thickness, but nevertheless cannot prevent the parts from becoming detached again if the gluing is faulty or has not yet set. Furthermore, the special shape on the edges of the web on the one hand and on the spars on the other hand must be regarded as complex.

Es ist deshalb aus der EP-OS 0214430 eine Anordnung bekannt, bei welcher die Stege keine randseitigen schlitzförmigen Ausnehmungen haben, sondern mit ihrer Schwalbenschwanzform in eine entsprechende Nut des Holmes eingezwängt werden müssen. Da also die Nuten beim Montieren aufgespreizt werden hängt die Güte der Verbindung wiederum vollständig von der Verleimung ab. Darüberhinaus besteht bei einer solchen Verzwängung die Gefahr, daß bei aus Holz bestehenden Holmen diese am Nutengrund reißen. Eine Montage der Stege in Längsrichtung der Holme wäre jedoch zu aufwendig und mühsam.An arrangement is therefore known from EP-OS 0214430 in which the webs do not have slot-shaped recesses on the edge, but with their dovetail shape must be squeezed into a corresponding groove in the spar. Since the grooves are spread out during assembly, the quality of the connection in turn depends entirely on the gluing. In addition, with such a squeeze there is a risk that with wooden spars they tear at the bottom of the groove. An assembly of the webs in the longitudinal direction of the bars would be too complex and tedious.

Es besteht deshalb die Aufgabe, einen Holzträger der eingangs erwähnten Art zu schaffen, bei welchem auch bei noch nicht vollständig abgebundener Verleimung oder nachlassender Klebkraft dennoch eine gute Halterung des Steges in den Nuten der Holme bestehen bleibt.It is therefore the task of creating a wooden support of the type mentioned at the outset, in which a good retention of the web remains in the grooves of the spars even when the gluing or adhesive strength has not yet fully set.

Die überraschende und den bisherigen Anordnungen widersprechende Lösung besteht darin, daß die Spreiz-Leiste ein separates, unabhängig von Holm Steg einsetzbares innerhalb der Nut oder am Nutengrund verrückbares Teil ist. Wird der Steg mit seinen schlitsförmigen Ausnehmungen in die schwalbenschwanzförmige Nut des Holmes eingepreßt und dabei auf die am Nutengrund anschlagende Spreizleiste aufgeschoben, wird er nicht nur entsprechend schwalbenschwanzförmig verformt, sondern aufgrund der Spreizkräfte und der Verformung gleichzeitig mit der Spreizleiste verklemmt. Treten nun auch bei noch nicht erfolgter oder mangelhafter oder im Laufe der Zeit schwächer gewordener Verleimung Kräfte an dem Träger auf, die dem Steg aus dem Holm herausbewegen möchten, wird dies durch die einer solchen Bewegung sofort folgende Spreizleiste, die nicht am Nutengrund oder innerhalb der Nut unverrückbar festliegt, durch eine Art Selbst-Verklemmung verhindert.The surprising solution, which contradicts the previous arrangements, is that the spreading strip is a separate part that can be moved within the groove or at the bottom of the groove, independently of the spar web. If the web with its slit-shaped recesses is pressed into the dovetail-shaped groove of the spar and pushed onto the spreader bar striking the base of the groove, it is not only deformed accordingly in the form of a dovetail, but is also jammed with the spreader bar due to the spreading forces and the deformation. If forces occur on the carrier even if the gluing has not yet taken place or is inadequate or has become weaker over time, and this would like to move the web out of the spar, this is immediately followed by such a movement of the expansion bar, which is not on the groove base or within the Groove is immovable, prevented by a kind of self-jamming.

Eine weitere Ausgestaltungsmöglichkeit der Erfindung von erheblicher oder eigener schutzwürdiger Bedeutung kann dabei darin bestehen, daß die Spreizleiste aus anderem insbesondere härterem Werkstoff als der Holm, vorzugsweise aus Hartholz, Kunststoff od. dgl. nicht schwindendem und/oder nicht quellendem Werkstoff besteht. Dies ist bei einer einstückig mit dem Holm hergestellten Spreizleiste nicht möglich, wenn nicht der gesamte Holm aus derart teuerem und aufwendigen Werkstoff bestehen soll. Somit kann also der Holm aus preiswertem und unter Umständen weicherem Werkstoff gefertigt sein und dennoch eine sichere und gute Verklemmung mit der Spreizleiste erzielt werden, ohne daß diese im Laufe der Zeit ihre Eigenschaften und damit ihre die Verleimung gut unterstützende Haltefunktion ändert.A further possible embodiment of the invention of considerable importance or of its own worthy of protection may consist in the spreading strip being made of other materials in particular harder material than the spar, preferably made of hardwood, plastic or the like. Non-shrinking and / or non-swelling material. This is not possible with a spreader bar made in one piece with the spar, if the entire spar is not to be made of such an expensive and complex material. Thus, the spar can be made of inexpensive and, under certain circumstances, softer material and still secure and good jamming can be achieved with the spreader bar, without this changing its properties over time and thus its holding function that supports the gluing well.

Vor allem bei Kombination der vorerwähnten Maßnahmen kann ein solcher Holzschalungsträger bei seiner Herstellung wesentlich früher aus einer Spannvorrichtung entnommen werden, als ein derartiger Träger, bei welchem die Verleimung zunächst aushärten oder trocknen muß, da die separate Spreizleiste von vorneherein eine genügend gute Haltekraft erzeugt, um auch bei ausgespanntem Träger ein sicheres Abbinden und Aushärten der Verleimung zu erlauben. Somit kann die Fertigung beschleunigt und verbilligt werden.Especially when combining the above-mentioned measures, such a wooden formwork beam can be removed from a tensioning device much earlier in its manufacture than such a beam, in which the gluing must first harden or dry, since the separate spreading strip generates a sufficiently good holding force from the outset in order to to allow the glue to set and harden securely even when the beam is stretched out. This means that production can be accelerated and made cheaper.

Besonders zweckmäßig ist es dabei, wenn die Höhe der im Querschnitt keilförmigen Spreizleiste der Tiefe der stirnseitigen Schlitze der Stege und gleichzeitig mindestens der Tiefe der schwalbenschwanzförmigen Nut der Holme entspricht. Dadurch reicht die Spreizleiste über die gesamte Einstecktiefe der Nut, so daß schon geringste Zugkräfte an der engen Eintrittsöffnung der Nut zu einer Selbst-Verklemmung führen. Dies könnte noch verstärkt werden, wenn die keilförmige Spreizleiste sogar etwas höher als die Nut wäre.It is particularly expedient if the height of the wedge-shaped cross-section corresponds to the depth of the front slots of the webs and at the same time at least the depth of the dovetail-shaped groove of the bars. As a result, the spreader bar extends over the entire insertion depth of the groove, so that even the slightest tensile forces at the narrow entry opening of the groove lead to self-jamming. This could be reinforced if the wedge-shaped spreader bar were even slightly higher than the groove.

Eine weitere Ausgestaltung der Erfindung von eigener schutzwürdiger Bedeutung, die die Verbindung zwischen Steg und Holm verbessert und vereinfacht und die Gefahr eines Aufsprengens des Steges durch die Spreizleiste erheblich vermindert oder sogar ausschaltet, kann darin bestehen, daß die Ränder der Stege wenigstens zwei parallele Schlitze haben und für jeden Schlitz eine Spreizleiste vorgesehen ist, die separat und unbhängig von dem Holm in diesen einsetzbar ist. Die zum Ausfüllen des schwalbenschwanzförmigen Nut-Querschnittes dienende Aufspreizung der Stegränder wird somit auf zwei Schlitze verteilt, so daß jeder Schlitz weniger stark aufgespreizt werden muß, dennoch aber eine entsprechende Querschnittsvergrößerung des Schlitzes und Anpassung an die Nut-Querschnittsform erzielt wird.Another embodiment of the invention of its own worthy of protection, which improves and simplifies the connection between the web and the spar and the risk of Blowing up of the web considerably reduced or even switched off by the spreader bar can consist in the fact that the edges of the webs have at least two parallel slots and a spreader bar is provided for each slot, which can be used separately and independently of the spar in these. The spreading of the web edges serving to fill the dovetail-shaped groove cross-section is thus distributed over two slots, so that each slot has to be expanded less, but a corresponding cross-sectional enlargement of the slot and adaptation to the groove cross-sectional shape is nevertheless achieved.

Dabei ist es besonders vorteilhaft, wenn jeweils zwei Spreiz-Leisten für zwei einander benachbarten Randschlitze am Übergang von den einander zugewandten Flachseiten zu den in Gebrauchsstellung am Nutengrund der Holme befindlichen Schmalseiten jeweils einen rechten Winkel haben und die außenliegenden Flachseiten keilförmig unter spitzem Winkel schräng geneigt sind. Dadurch ergibt sich eine gezielte Aufspreizung jeweils der äußeren Schichten der den Steg bildenden Platte, während der zwischen den beiden Schlitzen befindliche Bereich dieser Platte ein gleichmäßiges Widerlager über die gesamte Querschnittshöhe der keilförmigen Leiste bildet.It is particularly advantageous if two spreading strips for two adjacent edge slots at the transition from the facing flat sides to the narrow sides located in the use position on the groove base of the spars each have a right angle and the outer flat sides are inclined obliquely in a wedge shape at an acute angle . This results in a targeted spreading of the outer layers of the plate forming the web, while the area of this plate located between the two slots forms a uniform abutment over the entire cross-sectional height of the wedge-shaped strip.

Auch in diesem Falle können die beiden Spreizleisten einer jeden Randverbindung des Steges mit einem Holm aus Hartholz, Kunststoff oder dergleichen bestehen.In this case, too, the two spreading strips of each edge connection of the web with a spar made of hardwood, plastic or the like.

Eine gute Anpassung der in der Nut befindlichen Oberflächenbereiche der Stege ergibt sich, wenn die jeweils den Seitenwänden der schwalbenschanzförmigen Nut zugewandten Seiten des/der Spreiz-Leiste(n) der Negativschrägung dieser Nutenwandung entspricht.
Der Steg dieses Holzschalungs- oder Holzträgers kann aus Brettschichtholz bestehen, wobei die Oberflächen der einzelnen Holzschichten parallel zu der Stegoberseite verlaufen und die randseitigen Schlitze für die Spreiz-Leisten sich parallel zu diesen Holzschichten erstrecken können. Dies ergibt eine preiswerte Fertigung der Stege, wobei dennoch ein Aufsprengen der einzelnen Schichten vor allem dann vermieden werden kann, wenn die Spreizkräfte und Spreizbewegungen auf jeweils zwei parallele Schlitze verteilt werden.A good adaptation of the surface areas of the webs located in the groove results if the sides of the spreading strip (s) facing the side walls of the dovetail groove correspond to the negative bevel of this groove wall.
The bridge of this wooden formwork or wooden beam can be made of Glulam is made of wood, the surfaces of the individual wood layers running parallel to the top of the web and the edge slots for the spreading strips can extend parallel to these wood layers. This results in an inexpensive manufacture of the webs, but the individual layers can still be prevented from bursting open if the spreading forces and spreading movements are each distributed over two parallel slots.

Die Spreizungen der Ränder der Stege können dadurch klein gehalten und dennoch die übertragbaren Kräfte groß sein, wenn der Winkel des Querschnittes der schrägen Seitenfläche(n) der keilförmigen Leiste gegenüber der Einsteckrichtung bzw. gegenüber einer Senkrechten auf den Nutengrund so spitz oder klein ist, daß bei einer Zugbelastung des Steges aus der Nut zwischen Leiste und Randschlitz in der sich nach außen verengenden Nut eine selbsttätig zunehmende Klemmkraft besteht. Zwar ergibt sich eine solche Klemmkraft schon durch die Einklemmung der Spreizleiste beim Aufspreizen des bzw. der randseitigen Schlitze der Stege, jedoch könnte bei ungünstigem zu großem Winkel der Schlitzbereich des Steges von einem derartigen Keil wieder abrutschen. Dies kann durch einen entsprechend schlanken Winkel ausgeschlossen werden, wobei dadurch gleichzeitig auch die Spreizkräfte niedrig gehalten werden.The spreads of the edges of the webs can thereby be kept small and yet the transmissible forces can be large if the angle of the cross section of the oblique side surface (s) of the wedge-shaped strip relative to the direction of insertion or to a perpendicular to the base of the groove is so pointed or small that in the event of a tensile load on the web from the groove between the strip and the edge slot in the outwardly narrowing groove there is an automatically increasing clamping force. Such a clamping force results from the clamping of the spreading strip when spreading the or the edge-side slots of the webs, but the slot area of the web could slip off such a wedge again if the angle is too large. This can be ruled out by means of a correspondingly narrow angle, which at the same time also keeps the spreading forces low.

Der Winkel des Querschnittes der schwalbenschwanzförmigen Nut zwischen Nutengrund und Seitenwand ― und somit auch der entsprechende Keilwinkel der Spreiz-Leiste ― kann etwa 80 bis 89°, bevorzugt etwa 84°, 85° oder 86° betragen.The angle of the cross section of the dovetail-shaped groove between the base of the groove and the side wall - and thus also the corresponding wedge angle of the expansion bar - can be approximately 80 to 89 °, preferably approximately 84 °, 85 ° or 86 °.

Vor allem bei Kombination der vorbeschriebenen Merkmale und Maßnahmen ergibt sich ein Holzträger, bei welchem schon unmittelbar nach der Verpressung der Stege mit den Holmen aufgrund der separaten Spreizleisten entsprechende Verklemmungen hergestellt sind, so daß eine zusätzlich vorgesehene Verleimung ohne dauernde Einspannung und Verpressung aushärten und abbinden kann. Gegebenenfalls kann sogar auf eine Verleimung vollständig verzichtet werden. Auch eine nachträgliche Verschlechterung der Verbindung durch ein Schwinden der Spreizleiste oder ein Aufquellen, was zu einem Aufsprengen der Nut und damit ebenfalls zu einer Lockerung der Verbindung führen könnte, können dadurch vermieden werden, daß die Spreizleisten separate Teile sind, die entsprechende Werkstoffeigenschaften haben können.A combination of the features and measures described above results in a wooden girder, in which the bars with the spars are pressed immediately after pressing due to the separate spreading strips, corresponding clamps are produced so that an additionally provided gluing can harden and set without permanent clamping and pressing. If necessary, gluing can even be completely dispensed with. A subsequent deterioration of the connection due to a shrinkage of the spreader bar or swelling, which could lead to a cracking of the groove and thus also to a loosening of the connection, can be avoided in that the spreader bars are separate parts that can have corresponding material properties.

Nachstehend ist die Erfindung mit ihren ihr als wesentlich zugehörenden Einzelheiten anhand der Zeichnung noch näher beschrieben.The invention is described in more detail below with its details that are essential to it, using the drawing.

Es zeigt in schematisierter Darstellung jeweils im Querschnitt und nur für einen Rand:

Fig. 1
einen Holm und einen randseitig einmal geschlitzten Steg sowie eine separate Spreizleiste vor dem Zusammenfügen,
Fig. 2
einen Querschnitt eines erfindungsgemäßen Trägers, bei welchem der geschlitzte Bereich des Steges mit der in den Schlitz eingepreßten Spreizleiste gleichzeitig in die schwalbenschwanzförmige Nut des Holmes eingedrückt ist,
Fig. 3
eine der Figur 1 entsprechende Darstellung, wobei der Steg zwei parallele randoffene Schlitze hat und zwei sich ergänzende Spreizleisten für jeden dieser Schlitze vorgesehen sind, sowie
Fig. 4
die Montagestellung des Trägers mit zwei Spreiz-leisten gemäß Figur 3.

It shows a schematic representation of each in cross-section and only for one edge:
Fig. 1
a spar and a web slotted once on the edge and a separate spreading strip before assembly,
Fig. 2
2 shows a cross section of a carrier according to the invention, in which the slotted region of the web with the spreading bar pressed into the slit is pressed simultaneously into the dovetail-shaped groove of the spar,
Fig. 3
a representation corresponding to Figure 1, wherein the web has two parallel edge-open slots and two complementary spreading strips are provided for each of these slots, and
Fig. 4
the mounting position of the carrier with two spreading strips according to FIG. 3.

Ein jeweils in den Figuren 2 und 4 mit einer Querschnittshälfte dargestellter Holzschalungsträger 1 hat zwei durch einen Steg 2 auf Abstand gehaltene Holme 3, von denen jeweils einer dargestellt ist. Die Holme 3 haben an den einander zugewandten Seiten 3a im Querschnitt jeweils eine etwa schwalbenschwanzförmige Nut 4, die besonders deutlich in den Figuren 1 und 3 erkennbar ist. Der Steg 2 hat an seinen in diese Nuten 4 einführbaren Schmalseiten 2a gemäß Figur 1 und 2 eine, gemäß Figur 3 und 4 zwei schlitzförmige Ausnehmungen 5, die in Gebrauchsstellung im Inneren der schwalbenschwanzförmigen Nuten 4 durch eine beim Einfügen in die Nuten 4 in den Schlitz 5 eindringende, im Querschnitt sich zum inneren des Schlitzes 5 verjüngende Spreiz-Leiste 6 aufspreizbar und dadurch gemäß den Figuren 2 und 4 formschlüsig innerhalb der schwalbenschwanzförmigen Nut 4 festlegbar ist. Man erkennt beim Vergleich der Figur 1 mit Figur 2 bzw. der Figur 3 mit Figur 4 deutlich, daß die Schmalseite 2a des Steges 2 zunächst in ihrer Querschnittsdicke der Weite der Nut 4 an deren Eintritt an der Oberseite 3a des Holmes 3 entspricht, in Gebrauchsstellung dann aber durch die in den Schlitz 5 eingedrückte Spreizleiste 6 eine erheblich vergrößerte Abmessung hat, die die schwalbenschwanzförmige Nut 4 ausfüllt und somit eine formschlüssige Verbindung herstellt. Die Berührbereiche zwischen den Wandungen der Nut 4 der Holme 3 und dem Steg 2 können dabei zusätzlich in nicht näher dargestellter Weise mit Leim abgedichtet und dadurch auch diese Verbindung verbessert sein.A wooden formwork beam 1 each shown in FIGS. 2 and 4 with a cross-sectional half has two spars 3 which are spaced apart by a web 2, one of which is shown in each case. The crosspieces of the spars 3 each have an approximately dovetail-shaped groove 4 on the sides 3a facing one another, which can be seen particularly clearly in FIGS. 1 and 3. The web 2 has on its narrow sides 2a insertable into these grooves 4 according to FIGS. 1 and 2 one, according to FIGS. 3 and 4, two slit-shaped recesses 5, which in the use position inside the dovetail-shaped grooves 4 by inserting into the grooves 4 in the slot 5 penetrating, in cross-section tapering to the interior of the slot 5 spreading bar 6 can be spread and thereby can be fixed in a form-fitting manner within the dovetail-shaped groove 4 according to FIGS. 2 and 4. When comparing FIG. 1 with FIG. 2 or FIG. 3 with FIG. 4, one can clearly see that the narrow side 2a of the web 2 initially corresponds in its cross-sectional thickness to the width of the groove 4 at its entry on the upper side 3a of the spar 3, in the use position but then, due to the expansion bar 6 pressed into the slot 5, it has a considerably enlarged dimension, which fills the dovetail-shaped groove 4 and thus produces a positive connection. The contact areas between the walls of the groove 4 of the spars 3 and the web 2 can additionally be sealed with glue in a manner not shown, and this connection can also be improved as a result.

In beiden Ausführungsbeispielen ist nun vorgesehen, daß die Spreizleiste 6 ein separates, unabhängig von Holm 3 und Steg 2 einsetzbares Teil ist. Dies wird besonders deutlich in den Figuren 1 und 3. Dadurch ergibt sich eine Verklemmung dieser Spreizleiste 6 innerhalb der Schlitze 5, so daß bei einer Zugkraft auf den Steg 2 aus dem Holm 3 heraus der gewünschte Widerstand gegen eine Lösung einer solchen Verbindung gegeben ist, während bei einer einstückig mit dem Holm 3 am Nutengrund verbundenen Spreizleiste die beiden beidseits des Schlitzes 5 befindlichen Schenkel des Steges 2 wieder aus dieser Nut herausrutschen könnten.In both exemplary embodiments it is now provided that the spreading strip 6 is a separate part which can be used independently of the spar 3 and the web 2. This is particularly evident in FIGS. 1 and 3. This results in jamming this spreader bar 6 within the slots 5, so that with a tensile force on the web 2 out of the spar 3, the desired resistance to a solution of such a connection is given, while in a spreader bar integrally connected to the spar 3 on the base of the groove, the two on both sides of the Slot 5 located leg of the web 2 could slip out of this groove again.

Darüberhinaus kann auf diese Weise die Spreizleiste 6 aus härterem und wiederstandsfähigerem Werkstoff als der Holm bestehen, z.B. aus Hartholz, Kunststoff oder einem sonstigen nicht schwindendem und/oder nicht quellendem Werkstoff. Somit ergibt sich eine auch über lange Zeit dauerhafte Verbindung, die nicht durch Nässe oder Trockenheit gelockert werden kann, selbst wenn die Verleimung nicht vorhanden oder fehlerhaft wäre oder nachgelassen hätte.In addition, the spreading bar 6 can be made of harder and more resistant material than the spar, e.g. made of hardwood, plastic or another non-shrinking and / or non-swelling material. This results in a long-lasting connection that cannot be loosened by wetness or dryness, even if the gluing was absent or faulty or had weakened.

Gemäß den Figuren 2 und 4 entspricht die Höhe der im Querschnitt keilförmigen Spreiz-Leisten 6 der Tiefe der stirnseitigen Schlitze 5 der Stege 2 einerseits und andererseits der Tiefe der schwalbenschwanzförmigen Nuten 4 der Holme 3. Dadurch wird erreicht, daß die Aufspreizung der Ränder der Stege 2 über die gesamte Höhe der Nut verläuft. Gleichzeitig sorgt die enge Einführöffnung der Nut 4 aber auch dafür, daß der Steg 2 durch die keilförmigen Leisten 6 nicht aufgesprengt wird.According to Figures 2 and 4, the height of the wedge-shaped cross-section strips 6 corresponds to the depth of the front slots 5 of the webs 2 on the one hand and on the other hand the depth of the dovetail grooves 4 of the spars 3. This ensures that the edges of the webs are spread apart 2 runs over the entire height of the groove. At the same time, the narrow insertion opening of the groove 4 also ensures that the web 2 is not blown open by the wedge-shaped strips 6.

Vergleicht man die Ausführungsform gemäß den Figuren 1 und 2 mit der gemäß den Figuren 3 und 4, wird deutlich, daß bei der ersten Ausführungsform noch eine relativ starke Spreizung des geschlitzten Bereiches des Steges 2 in Kauf genommen wird. Eine geringere Verspreizung ergibt sich bei der zweiten Ausführungsform dadurch, daß die Ränder 2a der Stege 2 jeweils zwei parallele Schlitze 5 haben und für jeden Schlitz eine Spreizleiste 6 vorgesehen ist, die wiederum separat und unabhängig von dem Holm 3 in diesen einsetzbar ist. Dabei erkennt man, daß die Schlitze 5 nun eine geringere Stärke benötigen und die beiden Spreizleisten jeweils nur etwa die halbe Querschnittsdicke gegenüber der gemäß Figur 1 und 2 haben müssen, um dennoch vergleichbare Spreizwinkel innerhalb der schwalbenschwanzförmigen Nut zu erlauben. Besonders zweckmäßig ist dies natürlich dann, wenn der Steg 2 seinerseits eine genügend große Querschnittsdicke hat.If one compares the embodiment according to FIGS. 1 and 2 with that according to FIGS. 3 and 4, it becomes clear that in the first embodiment a relatively large spread of the slotted area of the web 2 is accepted. A smaller spreading results in the second embodiment in that the edges 2a of the webs 2 each have two parallel slots 5 and a spreading bar 6 is provided for each slot in turn can be used separately and independently of the spar 3. It can be seen that the slots 5 now require a smaller thickness and the two spreading strips only have to have approximately half the cross-sectional thickness compared to that according to FIGS. 1 and 2, in order nevertheless to permit comparable spreading angles within the dovetail-shaped groove. Of course, this is particularly expedient if the web 2 in turn has a sufficiently large cross-sectional thickness.

Die beiden Spreizleisten 6 für zwei einander benachbarte Randschlitze 5 gemäß dem Ausführungsbeispiel nach den Figuren 3 und 4 haben am Übergang von den einander zugewandten Flachseiten 6a zu den in Gebrauchsstellung am Nutengrund 4a der Holme 3 befindlichen Schmalseiten 6b jeweils einen rechten Winkel; die außenliegenden Flachseiten 6c hingegen sind keilförmig unter spitzem Winkel schräg geneigt. Somit wird der zwischen den beiden Schlitzen 5 befindliche Bereich des Steges 2 als ganzflächige Abstützung über die gesamte Nutenhöhe benutzt und keiner zusätzlichen Verzwängung unterworfen, während die außenseitig der Schlitze 5 befindlichen Stegbereiche gemäß Figur 4 an die Schwalbenschwanz-Form der Nut 4 angepaßt werden, wenn die drei Teile miteinander in Richtung des Pfeiles Pf1 (Figur 1 und 3) verpreßt werden. Wie bereits erwähnt können auch in diesem Falle die beiden Spreizleisten 6 einer jeden Randverbindung eines Steges 2 mit einem Holm 3 aus Hartholz oder Kunststoff od. dgl. bestehen und zu einer dauerhaften formschlüssigen Verbindung führen.The two spreading strips 6 for two adjacent edge slots 5 according to the exemplary embodiment according to FIGS. 3 and 4 each have a right angle at the transition from the mutually facing flat sides 6a to the narrow sides 6b located in the use position on the groove base 4a of the spars 3; the outer flat sides 6c, however, are inclined obliquely in a wedge shape at an acute angle. Thus, the area of the web 2 located between the two slots 5 is used as a full-area support over the entire groove height and is not subjected to any additional squeezing, while the web areas located on the outside of the slots 5 according to FIG. 4 are adapted to the dovetail shape of the groove 4 if the three parts are pressed together in the direction of arrow Pf1 (FIGS. 1 and 3). As already mentioned, the two expansion strips 6 of each edge connection of a web 2 with a spar 3 made of hardwood or plastic or the like can also exist in this case and lead to a permanent positive connection.

Der Winkel des Querschnittes der schrägen Seitenflächen 6c der keilförmigen Leiste 6 sowohl im Ausführungsbeispiel nach Figur 3 als auch nach Figur 1, der gegenüber der Einsteckrichtung gemäß dem Pfeil Pf1 bzw. gegenüber einer Senkrechten auf den Nutengrund 4a gebildet ist, ist im Aus führungsbeispiel so spritz und klein, daß bei einer Zugbelastung des Steges aus der Nut 4 entgegen dem Pfeil Pf1 zwischen Leiste 6 und Randschlitz 5 in der sich nach außen verengenden Nut 4 eine zunehmende Klemmkraft bildet, so daß also gewissermaßen eine Selbsthemmung oder Selbstklemmung vorliegt. Dazu trägt bei, daß die separate Spreizleiste 6 bei einer solchen Zugbewegung dieser Bewegung folgen könnte da sie nicht mit der Nut und dem Holm fest und einstückig verbunden ist, sondern von dem Schlitz 5 praktisch vollständig umschlossen ist.The angle of the cross section of the oblique side surfaces 6c of the wedge-shaped bar 6 both in the exemplary embodiment according to FIG. 3 and according to FIG. 1, which is formed with respect to the insertion direction according to arrow Pf1 or with respect to a perpendicular to the groove base 4a, is in the off exemplary embodiment so small and small that a tensile loading of the web from the groove 4 forms an increasing clamping force in the outwardly narrowing groove 4 against the arrow Pf1 between the strip 6 and the edge slot 5 in the groove 4 narrowing towards the outside, so that there is a certain self-locking or self-locking. This contributes to the fact that the separate spreading strip 6 could follow this movement with such a pulling movement since it is not firmly and integrally connected to the groove and the spar, but is practically completely enclosed by the slot 5.

Der Steg 2 kann z.B. aus Brettschichtholz bestehen, wobei die Oberflächen der einzelnen Holzschichten parallel zur Stegoberseite verlaufen und die randseitigen Schlitze 5 für die Spreiz-Leisten 6 sich parallel zu diesen Holzschichten erstrecken. Dennoch ist eine Aufsprengung der einzelnen Schichten durch die Leisten 6 nicht zu befürchten, da die Aufspreizung praktisch erst beim Eindrücken in die Nut erfolgt und die an der Oberseite 3a der Holme befindliche Verengung dieser Nut den außenbleibende Teil der Stege 2 zusammendrückt.The web 2 can e.g. consist of glulam, the surfaces of the individual wood layers run parallel to the top of the web and the edge-side slots 5 for the expansion strips 6 extend parallel to these wood layers. Nevertheless, there is no fear of the individual layers being blown open by the strips 6, since the spreading practically takes place only when they are pressed into the groove and the narrowing of this groove on the upper side 3a of the spars compresses the remaining part of the webs 2.

Es sei noch erwähnt, daß der Winkel des Querschnittes der schwalbenschwanzförmigen Nut 4 zwischen Nutengrund 4a und Seitenwand etwa 80° bis 89° bevorzugt etwa 84°, 85° oder 86° beträgt. Entsprechend werden in die Nut 4 eindringenden Teile des Steges 2 aufgespreizt, wozu die Spreiz-Leisten 6 zweckmäßigerweise entsprechende Schrägungswinkel haben.It should also be mentioned that the angle of the cross section of the dovetail-shaped groove 4 between the groove base 4a and the side wall is approximately 80 ° to 89 °, preferably approximately 84 °, 85 ° or 86 °. Correspondingly, parts of the web 2 penetrating into the groove 4 are spread out, for which purpose the spreading strips 6 expediently have corresponding helix angles.

Zusammenfassend ergibt sich also ein Holzträger, bevorzugt ein Holzschalungsträger 1 mit zwei durch einen Steg 2 auf Abstand gehaltenen Holmen 3, wobei die Holme 3 an den einander zugewandten Seiten 3a im Querschnitt etwa schwalbenschwanzförmige Nuten 4 und der Steg an seinen in diese Nuten 4 einführbare Schmalseiten 2a eine oder zwei, gegebenenfalls auch mehr schlitzförmige Ausnehmungen 5 haben, die in Gebrauchsstellung im Inneren der schwalbenschwanzförmigen Nuten 4 durch eine beim Einfügen in die Nuten 4 in den Schlitz 5 eindringende und einpreßbare, im Querschnitt sich zum Inneren des Schlitzes 5 hin, also vom Nutengrund 4a weg verjüngende Leiste 6 aufspreizbar und dadurch formschlüssig innerhalb der schwalbenschwanzförmigen Nut 4 festlegbar ist. Die Berührbereiche zwischen den Nuten 4 der Holme 3 und dem Steg 2 können mit Leim abgedichtet sein. Wesentlich ist, daß die Spreizleiste 6 oder die Spreizleisten 6 jeweils ein separates, unabhängig von Holm 3 und Steg 2 einsetzbares und einpreßbares Teil sind, die somit zu einer Selbst-Verklemmung führen und ungewollte Lösebewegungen auch bei fehlender oder schadhafter Verleimung verhindern.In summary, this results in a wooden girder, preferably a wooden formwork girder 1 with two bars 3 spaced apart by a web 2, the bars 3 on the sides 3a facing one another in cross section approximately dovetail-shaped grooves 4 and the web on its narrow sides insertable into these grooves 4 2a one or two, optionally also have more slit-shaped recesses 5 which, in the use position, inside the dovetail-shaped grooves 4 by means of a strip which, when inserted into the grooves 4, penetrates into the slot 5 and can be pressed in, in cross-section tapers towards the inside of the slot 5, i.e. away from the bottom of the groove 4a 6 expandable and thereby positively fixed within the dovetail groove 4. The contact areas between the grooves 4 of the bars 3 and the web 2 can be sealed with glue. It is essential that the spreading strip 6 or the spreading strips 6 are each a separate part which can be inserted and pressed in independently of the spar 3 and the web 2 and which therefore lead to self-jamming and prevent unwanted loosening movements even in the event of missing or defective gluing.

Claims (10)

1. A wooden girder, coffering or formwork girder (1), having two chords (3) maintained in spaced relationship by a web (2), the chords (3) at the sides (3a) facing each other having grooves (4) approximately dovetailed in cross section, and the web (2) at the narrow cants (2a) thereof insertable into said grooves (4) having at least one slot-shaped recess (5), in the position of use in the interior of the dovetailed grooves (4) said recess (5) being adapted to be spread and thereby to be form-lockingly fixed within the dovetailed grooves (4) by a strip (6) or the like which upon insertion into the grooves (4) penetrates the slot (5), said strip (6) tapering in cross section towards the inside of the slot (5), the contact areas between the grooves of the chords and the web preferably being sealed with glue or the like, characterized in that the spreading strip (6) is a separate part which is insertable independently of chord (3) and web (2) and is movable within the groove (4) or at the groove base (4a).
2. A wooden girder as claimed in claim 1, characterized in that the spreading strip (6) consists of different material, particularly of harder material than the chord, preferably of hardwood, synthetic material or like non-shrinking and/or non-swelling material.
3. A wooden girder as claimed in claim 1 or claim 2, characterized in that the height of the spreading strip (6) wedge-shaped in cross section corresponds to the depth of the slots (5) in the end faces of the webs (2) and at the same time corresponds at least to the depth of the dovetailed groove (4) of the chords (3).
4. A wooden girder, coffering or formwork girder according to the preamble of claim 1, characterized in that the edges (2a) of the webs (2) have at least two parallel slots (5) and for each slot (5) there is a spreading strip (6) provided which is insertable into the slot separately and independently of the chord (3).
5. A wooden girder as claimed in claim 4, characterized in that in each case two spreading strips (6) for two slots (5) adjacent to one another each have a right angle at the transition from the flat sides (6a) facing each other to the narrow cants (6b) which in the position of use are situated at the groove base (4a) in the chords (3), and the external flat sides (6c) are inclined wedgelike at an acute angle.
6. A wooden girder as claimed in claim 4 or claim 5, characterized in that two spreading strips (6) of each joint between the edge of the web (2) and a chord (3) consist of hardwood, synthetic material or the like.
7. A wooden girder as claimed in any one of claims 1 to 6, characterized in that the sides of the spreading strip(s) in each case facing the side walls of the dovetailed groove correspond to the negative slope of said groove wall.
8. A wooden girder as claimed in any one of claims 1 to 7, characterized in that the web consists of glued laminated wood wherein the surfaces of the individual laminae of wood run parallel to the upper side of the web and the slots for the spreading strips extend parallel to said laminae.
9. A wooden girder as claimed in any one of claims 1 to 8, characterized in that the cross section of the inclined side face(s) (6c) of the wedge-shaped strip (6) is at an angle relative to the direction of insertion (Pf 1) or relative to a perpendicular to the groove base (4a), which angle is so acute and small that when tensile load is applied to the web (2) to draw it from the groove (4) there is an increasing clamping force between strip (6) and slot (5) in the outwardly narrowing groove (4).
10. A wooden girder as claimed in any one of claims 1 to 9, characterized in that the angle of the cross section of the dovetailed groove between groove base and side wall is about 80° to 89°, preferably about 84°, 85° or 86°.
EP89108677A 1988-06-03 1989-05-13 Wooden coffering girder Expired - Lifetime EP0344505B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89108677T ATE70584T1 (en) 1988-06-03 1989-05-13 TIMBER FORMWORK BEAM.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3818905 1988-06-03
DE3818905A DE3818905C1 (en) 1988-06-03 1988-06-03

Publications (2)

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EP0344505A1 EP0344505A1 (en) 1989-12-06
EP0344505B1 true EP0344505B1 (en) 1991-12-18

Family

ID=6355773

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89108677A Expired - Lifetime EP0344505B1 (en) 1988-06-03 1989-05-13 Wooden coffering girder

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EP (1) EP0344505B1 (en)
AT (1) ATE70584T1 (en)
DE (2) DE3818905C1 (en)
DK (1) DK269389A (en)
ES (1) ES2028411T3 (en)
NO (1) NO892275L (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GR980100147A (en) 1998-04-27 1999-12-31 *�65tF fs@ K@*66 0� f9 Method and device for the manufacture of a drip irrigation conduit
CZ29272U1 (en) * 2015-12-15 2016-03-15 Ján Šivec Structural beam with wooden flange plates and reinforced composite web
AU2020396289A1 (en) * 2019-12-07 2022-06-16 Peri Se Filler beam assembly

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4195462A (en) * 1975-03-14 1980-04-01 Wood I Systems, Inc. Fabricated wood structural member
US3991535A (en) * 1975-03-14 1976-11-16 Keller James R Pressed-in dovetail type joint
DE2649576C2 (en) * 1976-10-29 1985-06-05 Kurt Orban Co., Inc., Wayne, N.J. Wooden beams
FR2373654A1 (en) * 1976-12-07 1978-07-07 Allombert Georges Composite timber steel beam for formwork - has I=section with steel T=sections built into joints of timber flanges and plywood web
US4249355A (en) * 1977-04-12 1981-02-10 Douglas E. Chatfield Modified dovetail joint
US4191000A (en) * 1978-02-27 1980-03-04 Timjoist, Inc. Wooden I-beam
DE3210928C2 (en) * 1982-03-25 1985-05-15 Michael 7437 Westerheim Moser I-shaped beam
US4638619A (en) * 1983-12-19 1987-01-27 Fischetti David C Wood I-joist and method of fabricating the same
US4967534A (en) * 1985-08-09 1990-11-06 Mitek Holding, Inc. Wood I-beams and methods of making same

Also Published As

Publication number Publication date
DE3818905C1 (en) 1989-08-31
DK269389D0 (en) 1989-06-02
EP0344505A1 (en) 1989-12-06
ATE70584T1 (en) 1992-01-15
ES2028411T3 (en) 1992-07-01
DE58900580D1 (en) 1992-01-30
NO892275L (en) 1989-12-04
DK269389A (en) 1989-12-04
NO892275D0 (en) 1989-06-02

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