NL8502575A - CONNECTION METHOD FOR WOODEN STRUCTURAL PARTS. - Google Patents

Description

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Connection method for wooden construction parts.

The object of the invention is primarily to provide a solution for connecting round timber construction parts. Namely, round posts of most softwood species show shrinkage cracks in the longitudinal direction and directed towards the heart. This makes it difficult to fasten construction parts together using conventional joining techniques such as bolts, rivets, etc., in such a way that sufficient safety is obtained. This fact has hitherto hindered the high-quality and large-scale use of round wood for types of construction in which, incidentally, it would come into its own. One can think here of supporting structures for architectural purposes and in particular so-called spatial structures, in which the material is loaded mainly in the fiber direction - so axially. For such applications, roundwood is ideally suited in terms of cross-section quantities and in terms of material properties of most available wood types.

The transfer of force from one construction element to another will generally take place via steel strips, which are incorporated in the ends of the bars.

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For this purpose, a slot can be made at each end to the width of the strip thickness and to the depth of the full bar width. Figure 1 shows the indicated situation in the end of a rod, called element 1. In this strip 2 is arranged in slot 3. Perpendicular to the width of strip 2, a hole 4 is drilled through the rod 1 and a hole 5 through the strip 2. A steel pipe 6 with a relatively thick wall is passed through this hole. This pipe has a length that is slightly less than the pole diameter, and has a rounded inside on both ends.

The width of strip 2 must also be smaller than this diameter, because otherwise the intended effect of the connection method is adversely affected. Each strip 2 must be fixed with at least two such tubes 6 on the end of a round wooden post 1 to prevent additional hinge points from being introduced. Especially when the pile is under compressive stress, additional deformations or buckling could otherwise occur.

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When a tensile or compressive force is now exerted on the strip in the direction of the pile, this force is communicated to the wooden pile via a bending moment in the tube 6. This has a splitting effect on the wood at the location of this tube. In most cases the applied force can initially be absorbed, but to prevent splitting or shrinkage cracks in the wood from widening under the influence of this force, you can use iron tubes around the wood to make a wire. -10 know the quality and thickness. To this end, a piece of iron wire 7 of sufficient length is passed through the tube 6 and placed around the wood on one side. This iron wire is then tightened so that it has the required course as accurately as possible, and finally the ends 15 of the iron wire are twisted together over a sufficient length 8 and thereby also fixed. At least two such iron wires are used per tube on either side of the wood, depending on the force introduced, the wire thickness and the dimensions of strip 2, tube 6 and rod 1.

Figure 2 shows the various parts that are essential for this connection type.

A suitable tool must be available for applying this iron wire. Such a tool is described, for example, in the publication "Manual 25" at the Delft Wire Collet "by P. Huybers, Technische Hogeschool, Delft, June 1984. The effect of the iron wire wraps 7 is that with further loading of the steel strip cracks in the wood is limited or counteracted and that after initial collapse of the wood at the location of the tube 6 a reinforcement gradually occurs again because the iron wire increasingly strings the wood together. That is, not only is a very much higher average strength achieved than is possible with the usual fasteners, but moreover a much smaller spread is found in the strength data, so that ultimately a high allowable strength may be maintained.

The twisted ends 8 of the iron wire 7 can be knocked flat against the wood for better appearance and to prevent injuries and with a staple γΛ -Λ ~ 7 ^

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- 3 - secured. The length of the twisted sections 8 must be long enough to provide sufficient security against tearing open.

Apart from the solution described above, which is mainly intended for joining round wooden construction parts through the use of a steel strip, it is also possible to attach a package of wooden construction parts of round or rectangular cross section to each other by drilling a hole throughout the package, by passing a tube through it in the same manner as described above and by passing two or more iron wire loops through this tube and around the wood. In this case, the tube fulfills the function of the traditional bolt and the iron wire that of the wood head and nut. This solution is suitable, inter alia, for the manufacture of rafters.

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Claims (2)

1. A connection method for wooden construction parts, characterized in that the force transfer is effected via metal strips, fitting into a slot in the wood, whereby strip and wood are mutually connected by means of at least two metal pipes and at least two through each tube lined metal wire loops that are tightly tensioned and secured. A connection method according to claim 1, characterized in that two or more parts brought along one another are directly connected - thus without the intervention of metal strips - through one or more metal pipes, which are arranged through these parts and through which at least two metal wire loops are fed that are tightly tensioned and then secured. 5302 575