Static structures (e.g. – buildings) – Machine or implement
Reexamination Certificate
1999-08-06
2001-09-04
Stodola, Daniel P. (Department: 3634)
Static structures (e.g., buildings)
Machine or implement
C052S749100, C052S749100
Reexamination Certificate
active
06282862
ABSTRACT:
FIELD OF THE INVENTION
This application is the national phase under 35 U.S.C. §371 of PCT International Application No. PCT/AU98/00316 which has an International filing date of Apr. 30, 1998 which designated the United States of America.
The invention relates to a structural member for construction of buildings such as houses. The invention has particular but not exclusive application in use as a chord for forming a roof truss for a building.
PRIOR ART
A metal roof truss is commonly constructed with box-section chords and C-section web members. The box-section chords are formed by two C-sections individually roll formed and then further fabricated by dimple formation for locating and/or fastening by welding, riveting, hole punched and bolted or screwed to close the two C-sections. The fabrication of the section is a specialised operation and adds additional cost and time to the manufacture of a chord.
Open sections are generally quicker and cheaper to manufacture than box-sections comprising two C-sections, but they lack the strength and stiffness required for chords. Thus, whenever open sections, such as channel and Z-sections are used in the fabrication of building frames and roof trusses, additional precautions such as providing oversized sections or additional structural support must be taken to compensate for their inherent strength deficiencies. This of course increases the cost of many structures formed therefrom.
In addition, effecting the joints between top and bottom chords and between web members and chords mostly requires specialised joining members or shaping for welding which adds to the cost and complexity of such structures.
SUMMARY OF THE INVENTION
It is an object of this invention to provide an alternative structural member suitable for forming the chord of a truss or other structural member.
In one aspect the invention broadly resides in an elongated open structural member having a cross-section including a minor flange, a major flange and a web interconnecting said flanges and having a section axis at right angles to the longitudinal axis of the structural member and passing through the flanges and wherein:
said web includes a linear portion which extends substantially coincident with the section axis but substantially less than the length of the section axis between the flanges, and a divergent portion which extends to one side of said section axis;
said minor flange extends to said one side of said section axis;
said major flange extends from said divergent portion to the opposite side of said section axis, and
the section configuration being such that an inverted and reversed corresponding open structural member is nestable within said open structural member with their respective linear portions overlapping each other and with each minor flange located in an abutting relationship against the underside of the adjacent major flange.
In another aspect the invention broadly resides in an elongated open structural member having a cross-section including a minor flange, a major flange, and a web interconnecting said flanges and having a section axis at right angles to the longitudinal axis of the structural member and passing through the flanges and wherein:
said web includes a linear portion which extends substantially coincident with the section axis but substantially less than the length of the section axis between the flanges, and a divergent portion which extends to one side of said section axis;
said minor flange laterally extends from said section axis to said one side;
said major flange extends from said divergent portion to the opposite side of said section axis, and
the section configuration being such that an inverted and reversed corresponding open structural member is nestable within said open structural member with their respective linear portions overlapping each other and with each minor flange locatable in an abutting relationship against the underside of the adjacent major flange.
The linear portion may be any suitable length but preferably it extends along a major portion of the section axis between the flanges. The term “suitable” is qualified by the particular use of the open structural member and where a corresponding member is used the length of the linear portion is such that it enables the linear portions to overlap.
The divergent portion may have any suitable shape. The divergent portion may be curved, straight, or include a series of straight segments. In a preferred embodiment the divergent portion is a single straight portion that diverges from the section axis at an acute angle.
Preferably the major flange extends at an acute angle from the divergent portion. When the open structural member is used as a chord with the major flange outermost, the linear portion being substantially less than the length of the section axis between the flanges provides an advantage that the divergent portion acts in part like a spring to withstand compression forces substantially acting in the direction of the section axis and thereby resist deformation of the major flange.
The linear portion connects to the minor flange at its end opposite the divergent portion. Preferably the minor flange extends from the linear portion at an angle of substantially 90 degrees. Alternatively, the linear portion may include a second divergent portion which extends to the minor flange. The second divergent portion may be curved, straight, or comprise a series of straight segments.
The minor flange is preferably shorter than the major flange and most preferably is shorter than the section of the major flange which extends between an intersection with the section axis and the major flange, and its free end. Preferably the intersection with the section axis occurs about midway across the major flange.
Preferably the flanges are substantially parallel or at least parts which are substantially diagonally opposite with respect to the section axis are substantially parallel. Preferably the major flange is substantially parallel with the minor flange.
Preferably the open structural member includes limiting means to restrict lateral movement with respect to the section axis of connected members along the section axis. Preferably the limiting means is a return flange extending along the free edge of the major flange.
The major and/or the minor flanges preferably both terminate in a return flange. The return flange preferably returns substantially parallel to the section axis. Preferably the return flange of the major flange is spaced further from the section axis than the free end of the minor flange so that a reversed and inverted corresponding open structural member may nest within the structural member.
The open structural member is preferably asymmetrical in shape and allows the nesting of an inverted and reversed corresponding open structural member with the minor flange of one open structural member locatable within the major flange of the other open structural member and overlapping of the linear portions.
In another aspect the invention resides in a chord member for a truss, the chord member being an open structural member as described above whereby the chord member may be disposed with its major flange outermost and with interconnections between intersecting chord members being made by overlapping respective linear portions with the minor flange of one chord member being substantially adjacent the underside of the major flange of the other chord member and the overlapping of the linear portions enabling through fastening of the respective chord members. In such arrangement the webs overlap at joints for connection to one another such as by bolting or screwing or welding and, if desired disposed with their minor flanges nested within the major flanges of the opposing chord member.
It is also preferred that the chords of said truss are interconnected by truss members which may be open section members suitably terminated for web to web connection to the webs of the top and bottom chord members.
The assembled truss with the open structural member forming the top and bottom
Harris Erica B.
Stodola Daniel P.
Weeks Peacock Quality Homes PTY, Ltd.
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