Abstract:
A roof truss and method of assembly. The roof truss of the invention has a first layer of top chord members and a bottom chord, a second layer of web members, and a third layer of top chord members and a bottom chord. The second layer is affixed to the first layer with first layer fasteners and the third layer is affixed to said second layer with second layer fasteners. The first layer fasteners pass through the second layer to engage the first layer from a first side of the roof truss and the second layer fasteners pass through the third layer to engage the second layer from the first side of the roof truss. Therefore, the truss components may be field assembled without having to turn the partially assembled truss. The use of common components and fasteners and the ease of assembly provide an economical alternative to known truss systems.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of U.S. Provisional Patent Application No. 61/156,974 entitled “ROOF TRUSS SYSTEM FOR LONG SPAN AND WIDE SPACING WITH ONE-SIDED ASSEMBLY,” filed Mar. 3, 2009, the contents of which are hereby incorporated by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    This invention was made with government support under Grant No. SBAHQ-05-I-0061 awarded by the U.S. Small Business Administration. The government has certain rights in the invention. 
     
    
     FIELD OF THE INVENTION 
       [0003]    This invention relates to a roof truss and method of assembly of the roof truss. In more particular, the roof truss of the invention is an assembly of readily available and low cost materials and fasteners that may be easily field assembled from one side of the truss. 
       BACKGROUND OF THE INVENTION 
       [0004]    A roof truss is a collection of structural elements, attached together to support a large load imposed by a roof of a building. A typical configuration of a roof truss is generally triangular is shape wherein a bottom chord and two sloped top chords form the perimeter of the truss. A plurality of vertical or diagonal webs may be located within the truss for additional support. Trusses are typically placed parallel to one another to form a support structure for a roof. 
         [0005]    Since trusses may be large and unwieldy, it is advantageous to be able to assemble a truss at a work site rather than transporting assembled trusses. Shipping costs for a bulky pre-assembled truss are significantly greater than shipping costs associated with shipping truss parts. 
       SUMMARY OF THE INVENTION 
       [0006]    The building roof truss of the invention is an assembly of readily available members, such as cold-rolled steel cross sections. In a preferred embodiment, the truss uses two C sections for the top and bottom chords and C or HAT sections for the webs. The C and/or HAT sections are configured for ease of assembly of the roof truss from one side. The truss of the invention is capable of longer roof spans and wider spacing than prior art trusses. The truss of the invention can achieve spans of approximately 50 feet with truss spacings of up to 10 feet. In contrast, typical known light gauge trusses span approximately 50 feet with 2 or 4 foot truss spacing. The difference in material cost and labor is therefore significant. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIGS. 1A and 1B  are elevation views of an assembled roof truss of the invention; 
           [0008]      FIG. 2  is a cross-sectional view of the roof truss of  FIG. 1 , taken along line  2 - 2  of  FIG. 1A ; 
           [0009]      FIG. 3  a cross-sectional view of the roof truss of  FIG. 1 , taken along line  3 - 3  of  FIG. 1B ; 
           [0010]      FIG. 4  is an enlarged perspective view of a partially assembled joint where a web member is affixed to a chord; 
           [0011]      FIG. 5  is an enlarged perspective view of an assembled joint where a web member is affixed between two adjacent chords. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0012]    Referring to  FIGS. 1-5 , shown is a roof truss  10  of the invention. Roof truss  10  has a bottom chord  12  that has a first member  14  and a second member  16  ( FIGS. 2 ,  3 ). First member  14  and second member  16  of bottom chord  12  are preferably open access beams, i.e., beams having an open or recessed face. In a preferred embodiment, c-channels are used, wherein the c-channels are positioned in a back-to-back orientation, i.e., wherein the open face of the c-channels are facing away from one another. Bottom chord  12  has a first end  18  and a second end  20  ( FIGS. 1A and 1B ). 
         [0013]    Left top chord  22  has a first member  24  and a second member  26  ( FIG. 2 ). First member  24  and second member  26  of left top chord  22  are preferably c-channels that are positioned in a back-to-back orientation. Left top chord  22  has a first end  28  and a second end  30 . First end  28  of left top chord  22  is proximate first end  18  of bottom chord  12 . 
         [0014]    Right top chord  32  has a first member  34  and a second member  36 . First member  34  and second member  36  of right top chord  32  are preferably c-channel beams that are positioned in a back-to-back orientation. Right top chord  32  has a first end  38  and a second end  40 . Second end  40  of right top chord  32  is proximate second end  20  of bottom chord  12 . 
         [0015]    A plurality of left vertical web members  42 A- 42 E span between bottom chord  12  and left top chord  22 . A plurality of right vertical web members  44 A- 44 E span between bottom chord  12  and right top chord  22 . Left vertical web members  42 A- 42 E and right vertical web members  44 A- 44 E preferably have a hat shaped cross section (see  FIGS. 4 ,  5 ) but may be constructed of any suitable open access beam. 
         [0016]    A plurality of left diagonal web members  46 A- 46 E span between bottom chord  12  and right top chord  22 . A plurality of right diagonal web members  48 A- 48 E span between bottom chord  12  and left top chord  32 . Left diagonal web members  46 A- 46 E and right diagonal web members  48 A- 48 E preferably have a hat shaped cross section, but may be constructed of any suitable open access beam. 
         [0017]    A central vertical web member  50  spans between bottom chord  12  and a second end  30  of left top chord  22  and a first end  38  of right top chord  32 . Central vertical web member  50  preferably has a hat shaped cross section, but may be constructed of any suitable open access beam. 
         [0018]    In a preferred embodiment, the hat shaped cross section of each of left vertical web members  42 A- 42 E, right vertical web members  44 A- 44 E, left diagonal web members  46 A- 46 E, right diagonal web members  48 A- 48 E, and central vertical web member  50 , is configured to have a central web surface  52  and a pair of flange surfaces  54  ( FIG. 4 ). 
         [0019]    Referring now to  FIGS. 2 and 3 , roof truss  10  of the invention is substantially symmetrical since major components, such as first member  14  and second member  16  of bottom chord  12  are provided on both a right and left side of web members  42 A- 42 E,  44 A- 44 E,  46 A- 46 E,  48 A- 48 E, and  50 . Similarly, left top chord  22  and right top chord  32  are assembled from first members  24 ,  34 , and second members  26 ,  36 , which are configured in a back-to-back configuration that is symmetrical about web members  42 A- 42 E,  44 A- 44 E,  46 A- 46 E,  48 A- 48 E, and  50 , as shown in  FIGS. 2 and 3 . Roof truss  10  may not be perfectly symmetrical since web members  42 A- 42 E,  44 A- 44 E,  46 A- 46 E,  48 A- 48 E, and  50  preferably are hat sections, which are not symmetrical when comparing a top side, i.e., a web side, and a bottom side, i.e., a flange side. 
         [0020]    To assemble roof truss  10  of the invention, first member  14  of bottom chord  10  is placed on a surface. In a preferred embodiment, first member  14  of bottom truss chord  10  is a C channel beam, wherein the C channel beam is positioned open side down, i.e., web side up. 
         [0021]    First member  24  of left top chord  22  is also placed on the surface wherein first end  28  is located proximate to first end  18  of first member  14  of bottom truss chord  10 . The first member  24  of left top chord  32  is preferably a C channel beam, wherein the C channel beam is positioned open side down, i.e., web side up. 
         [0022]    Additionally, first member  34  of right top chord  32  is placed on the surface wherein second end  40  is located proximate to second end  20  of first member  14  of bottom truss chord  10 . The first member  34  of right top chord  32  is preferably a C channel beam, wherein the C channel beam is positioned open side down, i.e., web side up. 
         [0023]    First member  14 , first member  24  and first member  34  make up first layer  35  ( FIG. 5 ) of roof truss  10 . 
         [0024]    Next, first ends of left vertical web members  42 A- 42 E, e.g., hat channel beams, are placed on first member  14  of bottom truss chord  12 . In a preferred embodiment, left vertical web members  42 A- 42 E have a pair of flange surfaces  54  and a web or central surface  52 . Second end of left vertical web members  42 A- 42 E are placed on first member  24  of left chord  22 . 
         [0025]    First ends of right vertical web members  44 A- 44 E, e.g., hat channel beams, are placed on first member  14  of bottom truss chord  12 . In a preferred embodiment, right vertical web members  44 A- 44 E have a pair of flange surfaces  54  and a web or central surface  52 . Second ends of right vertical web members  42 A- 42 E are placed on right chord  32 . 
         [0026]    First ends of left diagonal web members  46 A- 46 E, e.g., hat channel beams, are placed on first member  14  of bottom truss chord  12 . In a preferred embodiment, left diagonal web members  46 A- 46 E have a pair of flange surfaces  52  and a web or central surface  54 . Second ends of left diagonal web members  46 A- 46 E are placed on first member  24  of left chord  22 . 
         [0027]    First ends of right diagonal web members  48 A- 48 E, e.g., hat channel beams, are placed on first member  14  of bottom truss chord  12 . In a preferred embodiment, right diagonal web members  48 A- 48 E have a pair of flange surfaces  54  and a web or central surface  52 . Second ends of right diagonal web members  48 A- 48 E are placed on first member  34  right chord  32 . 
         [0028]    A first end of central vertical web member  50 , e.g., a hat channel beam, is placed on first member  14  of bottom truss chord  12 . In a preferred embodiment, central vertical member  50  has a pair of flange surfaces  54  and a web or central surface  52 . A second end of central vertical member  50  is placed on second end  30  of first member  24  and on first end  38  of first member  24 . 
         [0029]    In a preferred embodiment, first ends of left vertical web members  42 , right vertical web members  44 , left diagonal web members  46 , right diagonal web members  48  and central vertical web member  50  are secured to first member  14  of bottom chord  12  by securing one of the hat channel flange surfaces  54  and the hat channel web or central surface  52  to the C channel web of the first member  14  of bottom truss chord  12  with first layer fastener  53  (flange surfaces  54  shown affixed to first member  14  in  FIGS. 4 and 5 ). Fasteners  53  are preferably screws. However, other fasteners may also be used. Screws and other fasteners preferably have a head and a shank. 
         [0030]    Second ends of left vertical web members  42  and left diagonal web members  46  are secured to first member  24  of left top chord  22  by securing one of the hat channel flange surfaces  54  and the hat channel web or central surface  52  to the C channel web of the first member  24  of left top chord  22  with first layer fastener  53 . 
         [0031]    Second ends of right vertical web members  44  and right diagonal web members  48  are secured to first member  34  of right top chord  32  by securing one of the hat channel flange surfaces  54  and the hat channel web or central surface  52  to the C channel web of first member  34  of right top chord  32  with first layer fastener  53 . 
         [0032]    Second end of central vertical member  50  is secured to the ends of left top chord  22  and right top chord  32  by securing one of said hat channel flange surfaces  54  and hat channel web surface  52  with first layer fastener  53 . 
         [0033]    Left vertical web members  42 A- 42 E, right vertical web members  44 A- 44 E, left diagonal web member  46 A- 46 E, right diagonal web member  48 A- 48 E and central vertical member  50  make up second layer  56  ( FIG. 5 ) of roof truss  10 . 
         [0034]    Second member  16  of bottom truss chord  12  is placed on first ends of web members  42 A- 42 E,  44 A- 44 E,  46 A- 46 E,  48 A- 48 E. Second member  16  of bottom truss chord  12  is preferably made of a C channel beam, wherein the C channel beam is positioned open side up, i.e., web side down. 
         [0035]    Second left member  26  of left top chord  22  is placed on the second ends of web members  42 A- 42 E,  46 A- 46 E. Second left member  26  of left top truss chord  22  is preferably made of a C channel beam, wherein the C channel beam is positioned open side up, i.e., web side down. 
         [0036]    Second ends of web members  42 A- 42 E, and  46 A- 46 E are secured to second member  26  of left top truss chord  22  and second ends  44 A- 44 E and  48 A- 48 E are secured to second member  36  of right truss chord  32  by securing one of the hat channel flange surfaces  54  and the hat channel web surface  52  to the C channel web of second member  26  of left top truss chord  22  and second member  36  of right top chord  32  with second layer fastener  55  ( FIG. 5 ). 
         [0037]    Second right member  36  of right top truss chord  32  is placed on the second ends of web members  44 A- 44 E,  48 A- 48 E. Second right member  36  of right top truss chord  32  is preferably a C channel beam, wherein the C channel beam is positioned open side down, i.e., web side up. 
         [0038]    Second right member  36  of right top truss chord  32  is secured to the second end of web members  44 A- 44 E,  48 A- 48 E by securing one of the hat channel flange surfaces  54  and hat channel web surfaces  52  to the second member  36  of right top truss chord  32  with second layer fastener  55 . 
         [0039]    The assembly made up of second member  16 , second member  26  and second member  36  makes up third layer  58  ( FIG. 5 ) of roof truss  10 . 
         [0040]    Fasteners  53 ,  55  are applied from one side of truss assembly  10 , thereby eliminating a need to flip truss assembly  10  during the assembly phase. Fasteners  53 ,  55  may be readily available fasteners including bolts, screws or other inexpensive fasteners. 
         [0041]    Thus, the present invention is well adapted to carry out the objectives and attain the ends and advantages mentioned above as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes and modifications will be apparent to those of ordinary skill in the art. Such changes and modifications are encompassed within the spirit of this invention as defined by the claims.