Static structures (e.g. – buildings) – Machine or implement
Utility Patent
1998-09-01
2001-01-02
Aubrey, Beth A. (Department: 3635)
Static structures (e.g., buildings)
Machine or implement
C052S749100, C052SDIG006, C403S232100, C411S468000
Utility Patent
active
06167675
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a steel-wood system, more specifically a method for web-reinforcing structural wood members, and to a structural wood member web-reinforced in accordance with this method.
2. Brief Description of the Prior Art
Structural lumber used throughout the world for constructing buildings is available on the market in a plurality of forms and wood species. However, due to the orthotropic properties of wood, some species cannot be used efficiently in many applications and/or under particular conditions. Also, visual grading of structural lumber using as criteria exterior wood appearance restricts the use of an important quantity of slightly affected structural lumber to applications in which the stresses involved are considerably lower. A considerable amount of structural lumber is also discarded due to natural imperfections such as shrinkage, cracks, knots, orientation of the fibers, warping, etc.
To obviate the above discussed disadvantages, U.S. Pat. No. 4,586,550 granted to Kitipornchai on May 6, 1986 proposes to reinforce an elongate structural wood member by mounting sheet metal strips or plates onto the top and/or bottom faces of the wood member. The sheet metal strips or plates are formed with a plurality of integral teeth extending on one side of the strip or plate, perpendicular thereto. In order to mount each sheet metal strip or plate, these teeth are driven into the wood member. Those of ordinary skill in the art will appreciate that these sheet metal strips or plates enhance the resistance of the wood member to bending.
Usually, an elongated structural wood member is, in cross section, wider than thick. Accordingly, the two edge surfaces of an elongated structural wood member are generally narrow and are used to secure a floor, a ceiling, a roof, wall covering, etc. Those of ordinary skill in the art will appreciate that metal sheet strips or plates applied to the top and bottom edge surfaces of a conventional floor joist (such as for example a wood joist 1½″ thick and 7½″ wide), in accordance with the teaching of U.S. Pat. No. 4,586,550 (Kitipornchai), interfere with fixation of the floor and ceiling onto the top and bottom narrow edge surfaces of the elongated structural wood member; an alternative method of fixation is required.
Also, use of sheet metal strips or plates onto only a portion of the length of the elongated structural wood member, as taught by U.S. Pat. No. 4,586,550 (Kitipornchai), creates mechanical disparities along the structural wood member. Moreover, there is no increase of the shearing stress the elongated structural wood member is capable of withstanding. Finally, the sheet metal reinforcement (strips or plates) cannot be installed onto the elongated structural wood members of an already erected construction.
Those of ordinary skill in the art will also appreciate that sheet metal reinforcement (strips or plates) as taught by U.S. Pat. No. 4,586,550 (Kitipornchai) fails to uniformly compensate for the wood defects and therefore to improve the long term behaviour of the elongated wood members.
OBJECTS OF THE INVENTION
An object of the present invention is therefore to provide a steel-wood system capable of eliminating the above discussed drawbacks of the prior art.
Another object of the invention is to provide a method for web-reinforcing structural wood members that (a) increases the rigidity of the structural wood member, (b) improves the mechanical resistance thereof to bending stresses, shearing, direct compression, direct tension and any combination thereof, (c) fights directly the defects, natural or not, of wood, (d) raises the grade of the structural wood members, and (e) saves both wood and money.
A further object of the present invention is to provide a structural wood member web-reinforced in accordance with the above method.
SUMMARY OF THE INVENTION
More specifically, in accordance with the present invention, there is provided a method for web-reinforcing an elongated structural wood member defining first and second opposite edge surfaces, and first and second opposite web surfaces, comprising the steps of applying a longitudinal metal reinforcement to at least one of the first and second web surfaces, and fixedly securing this metal reinforcement to the wood of the structural wood member substantially over the entire length of the metal reinforcement.
Preferably but not exclusively, the metal reinforcement is fixedly secured to the wood of the structural member at predetermined intervals substantially over the entire length of the metal reinforcement by means of metal teeth integral with the metal reinforcement.
Applying the metal reinforcement to at least one web surface of the elongated structural wood member and fixedly securing it to the wood substantially over the entire length of the metal reinforcement present, in particular but not exclusively, the following advantages:
the rigidity of the structural wood member is increased;
the mechanical resistance of the elongated structural wood member to bending stresses, shearing, direct compression, direct tension and any combination thereof is increased;
the defects, natural or not, of wood are compensated for to thereby raise the grade of the structural wood members;
etc.
The present invention also relates to a method for web-reinforcing a wood joist defining a top edge surface, a bottom edge surface opposite to the top edge surface, a first lateral web surface, and a second lateral web surface opposite to the first lateral web surface, comprising the step of applying a longitudinal metal reinforcement to at least one of the first and second lateral web surfaces, and fixedly securing this metal reinforcement to the wood of the joist at predetermined intervals along the length of the metal reinforcement by means of metal teeth integral to the metal reinforcement.
According to preferred embodiments:
the applying step comprises applying a longitudinal sheet metal strip to the web surface;
the joist comprises an upper longitudinal 90° edge connecting the web surface with the top edge surface and a lower longitudinal 90° edge connecting the web surface with the bottom edge surface, and the applying step comprises applying an upper longitudinal sheet metal strip to the web surface and placing an upper longitudinal edge of the upper sheet metal strip adjacent to the upper longitudinal 90° edge of the joist, and applying a lower longitudinal sheet metal strip to the web surface and placing a lower longitudinal edge of the lower sheet metal strip adjacent to the lower longitudinal 90° edge of the joist; and
the metal reinforcement is made of sheet metal, the securing step comprises the step of stamping the teeth in the sheet metal, and the stamping step comprises stamping the teeth by pairs and making a sawtooth cut to simultaneously produce respective, generally diagonal sawtooth edges of both teeth of a pair.
Further in accordance with the present invention, there is provided a web-reinforced elongated structural wood member defining first and second opposite edge surfaces, and first and second opposite web surfaces, comprising a longitudinal metal reinforcement applied to at least one of the first and second web surfaces, and means for fixedly securing the metal reinforcement to the wood of the structural member substantially over the entire length of the metal reinforcement.
Preferably but not exclusively, the securing means comprises teeth formed integral with the metal reinforcement, distributed at predetermined intervals along the length of the metal reinforcement, and driven into the wood of the structural member to fixedly secure the metal reinforcement to the wood of the structural member.
The present invention still further relates to a web-reinforced wood joist defining a top edge surface, a bottom edge surface opposite to the top edge surface, a first lateral web surface, and a second lateral web surface opposite to the first lateral web surface, comprising a longitudina
Aubrey Beth A.
Birch & Stewart Kolasch & Birch, LLP
Les Bois Laumar Inc.
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