Static structures (e.g. – buildings) – Openwork; e.g. – truss – trellis – grille – screen – frame – or... – Side-by-side terminus shafts; e.g. – truss
Patent
1980-08-08
1983-02-08
Bell, J. Karl
Static structures (e.g., buildings)
Openwork; e.g., truss, trellis, grille, screen, frame, or...
Side-by-side terminus shafts; e.g., truss
52642, E04C 224
Patent
active
043720935
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a truss of lattice type, comprising an upper and a lower chord and between the chords inclined struts fastened to the chords in a zig zag pattern. The chords are often made of wood and the struts of metal and the invention aims specifically to problems that arise in connection with this type of truss.
In earlier trusses of this type the struts are attached to the chords by clamping means or by other fastening means which are adapted to enter into the wood material as screws or nails. These fastening means have certain disadvantages, one of them being that the joint between the struts and chords of wood becomes weakened when the wood dries and shrinks. In case of varying loads there is furthermore the risk that a play arises in the joints. These disadvantages are serious in that the strength of the truss may become substantially lower than calculated, the result being unexpected failures.
The invention aims at a solution of these problems in that the struts enter into recesses in the chords and are fastened in these recesses by a hardening and adhering material which fills out the space around the struts within the recesses.
By this arrangement the weakening of the chords by the recesses for connecting the struts is compensated by the filling material. Secondly is achieved a fixing of the joint between the struts and the chords, so that the strength of the joint is not lessened in course of time by drying of the wood and no play is allowed to be initiated because the joint is subjected only to resilient deformations.
As joining material a hardening material which also should adhere both to the wood in the chords and the metal in the struts is preferably used. The strength of the material itself and of the joints therebetween and the components must of course be sufficient for resisting occurring forces. This means that in general the joining material must have the same compressive and tensile strength as the material in the chords and in the struts. Suitable adhering materials can be polyurethane plastic and epoxy glue.
BRIEF DESCRIPTION OF THE DRAWINGS
Closer details of the invention appear from the following specification with appended drawings wherein like members bear like reference numerals and wherein:
FIG. 1 is a side view of a truss according to the invention,
FIG. 2 is a perspective view of a separate chord according to the invention.
FIG. 3 is a detail in perspective of a joint for the struts.
FIG. 4 is the same detail as in FIG. 3 but with joining material in the joint.
FIG. 5 is a side view of the joint.
FIG. 6 is a second embodiment of the joint.
FIG. 7 is a view of a girder with joints according to a third embodiment of the invention.
FIG. 8 is a section on a larger scale on the line 8--8 in FIG. 7 showing the chord without the struts.
FIG. 9 is a section on the line 9--9 in FIG. 8.
FIG. 10 is the same section as in FIG. 8 showing both the chord and the struts.
FIG. 11 is a section on the line 11--11 in FIG. 10.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, a truss 10 according to the invention comprises chords or flanges 11 and 12 of wood and a web in the form of inclined struts 13 of metal, suitably steel. The struts can be tubular or solid and they can form a continuous zig zag shaped bar as shown in FIG. 1. Possible joints in this bar are placed at the places where the web is countersunk into the chords. With reference to FIG. 2, a separate chord 12 includes recesses 15 for the struts 13. FIG. 3 shows in perspective a detail of how the bent portion 16 between two struts in a continuous zig zag bar 13 is inserted in a recess 15. FIG. 4 shows the same view as FIG. 3 but with the joint filled with binding material 17.
With reference to FIG. 5, the curved intermediate portion 16 is placed between two struts in a continuous zigzag bar at a certain depth below the upper surface of the upper chord 12, so that the binding material 17 covers the portion 16 which firstly improves the strength and secondly improves the heat insulation between the
REFERENCES:
patent: 2421197 (1947-05-01), Green
patent: 3019491 (1962-02-01), Troutner
patent: 3452502 (1969-07-01), Price
patent: 3592717 (1971-07-01), Gaughran
patent: 3813842 (1974-06-01), Troutner
patent: 4159606 (1979-07-01), Kindberg
Bell J. Karl
Frelena AB
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