FI57815C - KOMBINATIONSBALK - Google Patents

Description

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Petent- oeh reflsterstyrelaen 'AnaMon utiajd och etc. etc. «krtft« i pubiiewud 30.06.80 (32) (33) (31) Pyy ^ «« y «Tuoikuui — u * iH prf © rit * t (71) State Technical Research Center, Vuorimiehentie 5, 02150 Espoo 15 »

Suomi-Finland (FI) (72) Pekka Luotonen, Espoo, Yrjö Tolonen, Espoo, Finland-Finland (FI) (7M Esko Friman (5k) Combined bar - Kombinationsbalk

The invention relates to a composite beam comprising a web of wood, wood-based board or plastic and a metal sheet bent around it, on which teeth or similar projections are stamped to attach it to the web.

Various wooden beams, columns or rods with a web in the web are commonly used in the primary or secondary structures of buildings. Composite beams made up of different parts are known per se and consist of a web plate and wooden rafters attached to it with glue, nails or screws. The attachment of the chord to the web plate takes place alone with glue or together with nails or screws, and the curing time required by the glue is achieved in the press, with nails or screws.

German Application Nos. 2,021,028 and 2,042,800 disclose examples of known composite beam structures. The previous publication shows a wooden beam, the deflection of which has been reduced by placing a metal strip on the side subjected to tensile stress. The purpose of the strip is to receive most of the 2 57815 tensile stresses. The strip can also be used to create tension in the beam by warping the wooden beam before attaching the strip.

The latter application discloses a composite beam, the web of which is a metal plate and the chords are attached to it, e.g. by nailing wooden slats.

British Patent Publication No. 1,063,701 discloses a composite structure consisting of a strip or strips of wood and a metal sheet bent around them. The metal plate is attached to the wooden part with teeth and possibly also with nails or screws. The main purpose of the wooden part is then to make it easier to attach the roof panels or other components to the beam structures.

However, the known beam beams have many drawbacks. With beams formed of wood material alone, the biggest drawback in use is related to the deflections, of which the vibration of the structure caused by the moving load in particular is perceived as a factor that severely impairs the living comfort. At long spans and long-term loads, the relatively low stiffness and high creep of the wood cause harmful deflections that are usually clearly visible.

The sensitivity of wood to moisture, especially in enclosure structures, causes undesirable deformations as the humidity conditions vary.

The massiveness of the solid wood structures used causes an additional load on other structures and the uneconomical use of wood. Similarly, current frame solutions in load-bearing or non-load-bearing structures waste wood material, especially in thick walls, and are poor in terms of the thermal economy of the structure. The use of a metal web in a composite beam is not desirable, because then a so-called a cold bridge between different structures, which is sought to be avoided.

Disadvantages in the manufacture of glued structures include: Controlled factory conditions and precise process control and compression are required for humidity and temperature throughout the drying of the adhesive. In addition, manufacturing is labor-intensive.

The nail joint can be made in either factory or site conditions. However, its disadvantage is that the number of nails required for strength easily becomes unreasonably large, in which case the areas of the parts have to be increased only in order to accommodate the required number of nails of 3,57815. Too dense nailing causes cracking. Nail joints creep under permanent loads and cause deflection over time. Nail plates are usually used when it is desired to connect the wooden parts of the structure to each other. Normal stresses are taken on the wood and the nail plate only acts as a connector and stress transducer. Tensioning of wooden beams has not been successful so far.

The object of the invention is to avoid the above-mentioned drawbacks and to provide a new component with improved properties. This is achieved by the features of the invention set out in the characterizing part of claim 1.

Advantages of the structure according to the invention include the following: - Significantly higher stiffness compared to the wooden structure alone. The high stiffness is due to the high modulus of elasticity of the metal and the almost non-slip joint of the chord and the web plate.

Manufacturing is fast, simple and process-like.

Possibility to use all types of stretchers. They can be asymmetrical in shape and very large in cross section.

The lateral stiffness of the structure can be adjusted by the shape of the chords.

The simple shape of the structure allows for the tight installation of thermal insulation, whereby the building part becomes thermally good, because there are no or minimized through massive and thermally conductive body parts.

Increasing the height of a structure is easy and often economically advantageous in terms of both thermal insulation and material consumption.

Surface cladding panels or other structures associated with chords can be easily and securely fastened in many different ways.

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The structure has a low weight and volume, which makes its transfer costs low.

Possibility of stress work in the structure.

The structure can be produced as a continuous strip from which the required lengths are cut.

The structure's web board is suitable for lumber, glulam and almost all wood-based boards and plastic.

There are no special requirements for the manufacturing conditions. _

The toothed joint between the chord and the web utilizes the web throughout its thickness, thus avoiding shear fracture in the surface layer of the web.

In the following, the invention and other advantages obtained by it will be explained in detail with reference to the accompanying drawing.

Figure 1 shows a section of an embodiment of a composite structure according to the invention.

Figure 2 shows a section of another embodiment of the invention.

Figure 3 shows a section of a third preferred embodiment of the invention.

Figures 4a and 4b show a section of a fourth preferred embodiment of the invention.

Figure 5 shows another preferred embodiment of the invention.

According to Fig. 1, the composite structure comprises, for example, a plywood web 11. A sheet metal girder 12 is placed at the edges of the web plate 11. Teeth 13, 14 are made by stamping on the sides of the sheet metal, which may be wider in either the longitudinal or transverse direction of the chord. . Likewise, the teeth 15 needed for the parts to be fastened to the structure can be stamped on different sides of the chord at the desired points. In the manufacturing step of the structure, the sheet metal girder is bent around the web plate, whereby the teeth 13, 14 penetrate the web plate 11, locking the chord 12 in place.

5,57815

Figure 2 shows another preferred embodiment of the invention. In this embodiment, the web plate 21 may be of the same material, e.g. plywood, as in the example of Figure 1. The brace damper 22 also otherwise corresponds to the brace damper of Fig. 1, but the teeth 23-26 stamped thereon are formed so that they are automatically guided to the sides. Such self-steering greatly increases the strength of the joint. Self-steering is achieved simply, for example, by slightly pre-bending the teeth 23-26 in the direction in which they are to be applied. This self-steering can also be achieved by the shape of the teeth.

Figure 3 shows an embodiment of the invention which gives the best strength against transverse stresses from the above. formed around a web plate 31 of the chord 32 is stamped teeth 33 and 34. Teeth 33 and 34 have been formed so long that the chord and a web plate between the final stage of attachment of the teeth 33, 34 collide with the opposite side of the metal sheet, which takes place in the so-called kotkautuminen. That is, the tooth tip 33a, respectively, 34a preferably bends into a semicircular shape, resulting in a highly secure lock. Also in this example, the web plate 31 is plywood.

Figure 4a shows a preferred embodiment of the invention which achieves a significant additional advantage. In this example, too, the web plate 41 is surrounded by a flapper 42. The fixing of the flapper can be made by any of the tooth shapes shown in Figures 1-3. However, a substantial advantage in this example is achieved by protrusions to which the cladding panel or some other structure can be fixedly or suspended by welding, soldering, screws or otherwise.

In Fig. 4b, the cladding panel insulations and / or other structure 45 can also be placed without fastening on top of the projections or fastened, e.g. with sheet metal screws, through the projections.

Figure 5 shows a preferred embodiment of the invention. In this example, the edge of the web plate 51 is surrounded by a stretcher plate 52. However, the stretcher plate is formed to be spacious in cross section. Shapes other than rectangular can be used as needed. The presented solution allows the filling material 53 to be used inside the stretcher plate. The filler can be, for example, wood, board, 6 57815 some mass or thermal insulation. This embodiment can also be easily provided with teeth 54, 55, by means of which, for example, the cladding plate can be easily attached to the surface of the beam. Otherwise, fastening can be done by nailing, staples, screws, rivets, welding, etc.

A significant additional advantage is obtained with an embodiment of the invention in which the chords are tensioned before the damper is pressed onto the web plate. If only a certain normal tension, either compression or tension, is applied to only the second chord, before it is pressed onto the web plate, a tensioned beam is created which is known to have improved properties without tension under bending stress compared to the fabricated beam. The compression applied to the chord prior to clamping can prevent the web from buckling.

The invention has been described above with reference to only a few preferred examples. It is natural that the invention should not be limited in any way to the examples given, but that many modifications are possible while still remaining within the scope of the inventive idea set forth in the following claims. The sheet metal used for the chord may have profiling that stiffens the chord, makes it easier to handle, and increases the surface area of the static sheet used for the chord.

Claims (3)

7 5781 5 A composite beam comprising a web (11, 21, 31 41, 51) of wood, wood-based board or plastic and a metal plate (12, 22, 32, 42, 52) bent around it, with embossed teeth (13, 23, 33) or similar projections for attaching it to the web, characterized in that the width of the web (11, 21, 31, 41, 51) is relatively large compared to the thickness of the web and the metal sheet chords are attached to each edge of the web, the metal plate embossed teeth (13, 23, 33) are mainly attached to the side surfaces of the web so that they extend through the web and, during the manufacturing step, preferably engage against the opposite girder. A composite beam according to claim 1, characterized in that the teeth (23-26) stamped on the metal plate (22) forming the chord are made asymmetrical or slightly pre-bent so that during the joint manufacturing step the teeth are guided independently in different directions, increasing the joint strength. Composite beam according to Claim 1 or 2, characterized in that the metal chord plates (12, 22, 32, 42, 52) are subjected to tension before the chord is connected to the web plate.