Abstract:
The present invention is directed to a truss system comprising first and second chords and a number of joists in bolted connection to form a load bearing structure. The first and second chords extend longitudinally in parallel alignment to form the beams upon which a load will be spread across. The first and second diagonal members of a joist are aligned at approximately 45 degree angles to the first and second chord, and perpendicularly to each other, to maximize the load bearing capabilities of the truss system. By utilizing a utility support grid to couple a first truss to a second truss, the present invention can support a load spread over a greater area.

Description:
RELATED APPLICATION  
       [0001]    This application is a non-provisional application which claims the priority of prior Provisional application Ser. No. 60/242,964, entitled “TRUSS SYSTEM FOR UTILITY SUPPORT GRIDS, AND ASSOCIATED METHODS”, filed Oct. 23,2000, which is hereby incorporated by reference into this application. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates generally to truss systems for load bearing applications, including commercial building support structures and more particularly, to bolted truss systems for load bearing applications.  
           [0004]    2. Description of the Related Art  
           [0005]    In the erection of certain kinds of buildings, such as hangars and halls, there is a frequent need for steel trusses capable of spanning considerable distances or for supporting heavy loads. In many cases, it is desirable to design these steel trusses as generally rectangular frames including a pair of generally horizontally extending, longitudinal chords, an upper one and a lower one, which are interconnected at their respective ends by vertical posts and between their ends by a web of struts and ties (collectively, bar joists). In order to combine maximum strength with minimum weight in the completed truss, the various members thereof must be joined together with great care and accuracy in a pattern, in which they interact as efficiently as possible in a manner to give mutual support and thus prevent distortion of the truss under the expected load. Support grids are used at the ends to interconnect a first truss with one or more parallel trusses to create a truss system for support.  
           [0006]    Typically, these trusses are prefabricated in a factory to a specified dimension. However, a problem in the prior art is that the bar joists used with building trusses are difficult to obtain. These trusses have a very long lead-time and impact building projects from a cost and time point of view. What is needed is a truss system that may be constructed with bolts, for ease of construction and placement, and to reduce costs. Additionally, it is desired to have a combined truss and support grid to form a truss system.  
           [0007]    For background, the following patents are incorporated herein by reference: 4,637,193; 5,964,068; 4,637,193; 5,060,907; 3,994,111; 4,073,114; 4,277,923; 4,586,759; 4,934,886; 5,046,291; 5,060,907; 5,355,650; 5,363,513; 5,425,593; 6,073,414; 5,771,653; 4,836,436; 4,506,487; 5,964,068.  
         SUMMARY OF THE INVENTION  
         [0008]    The principal objects and advantages of the present invention are to provide a truss system for structural support in load bearing applications; providing such a device that can be quickly assembled and properly positioned for use; providing such a device that is simple in construction, utilizing bolted connections and off-the-shelf metal framing in lieu of welded connections; providing such a device that is inexpensive in comparison to prior art designs; providing such a device that combines a truss system with a utility support grid; and providing such a device that is easily modified in selected dimensions to allow for optimized use in varying load bearing applications.  
           [0009]    These objects and advantages are attained by the truss system of the present invention that comprises first and second chords in a parallel arrangement and coupled together at a set distance by a number of joists. The joists angularly subtend approximately 90 degrees in a first bolted connection with the second chord and a second bolted connection with the first chord. The first and second diagonal members of a joist are aligned at approximately 45 degree angles to the first and second chord. The configuration of the joists partition the first chord into (n) number of upper chord members and partition the second chord into (n-1) number of lower chord members. A support grid couples a first truss to a second truss with a cross configuration of framing members.  
           [0010]    The uses of the invention are typically in construction of commercial buildings, including new building constructions or the retrofit of existing buildings as a secondary structural support system. The invention may also be used in retrofitting a facility where the existing structure will not support the loads imposed to it. In one example, existing structures are sometimes inadequate when they must incorporate cable trays and overhead utility support grids. The invention may further be used as a secondary support system, without utility grids, or particularly when bar joists are not available.  
           [0011]    The truss system of the invention can be constructed on the job site and in a manner that is faster than the prior art. In one aspect of the invention, the truss system also incorporates the utility grid as a part of the truss system. Preferably, all trusses use off-the-shelf metal framing. The truss system of the invention also preferably uses bolted connections, from chord to web, in lieu of welded connections. The invention may have welded joints, but preferably does not incorporate welded connections.  
           [0012]    Other advantages and components of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, which constitute a part of this specification and wherein are set forth exemplary embodiments of the present invention to illustrate various objects and features thereof. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a side elevational view of a truss system in accordance with the present invention;  
         [0014]    [0014]FIG. 2 is a cross-sectional view taken along line  2 - 2  of FIG. 1 showing the support grids between a series of trusses of the present invention;  
         [0015]    [0015]FIG. 3 is a cross-sectional view taken along line  3 - 3  of FIG. 1 showing the support grids between a series of trusses of the present invention and connections to the truss system; and  
         [0016]    [0016]FIG. 4 is a partial side elevational view of the truss system of the present invention showing the chords, the diagonal members of a joist, and the bolted connections for securing the elements together. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]    Referring now to the drawings, FIGS. 1 and 2 show a truss system  5  in accordance with the present invention. The truss system  5  comprises at least one truss  10  having a first chord  11  and second chord  12  rigidly coupled together by joists  13 , and a support grid that couples adjacent trusses together.  
         [0018]    The first chord  11  and second chord  12  are in substantially parallel alignment, extending lengthwise transversely in the horizontal plane. The first chord  11  is located vertically above the second chord  12  and is separated therefrom by a chord separation distance, indicated generally at A on FIG. 1. Both chords  11  and  12  are comprised of framing members that are elongate in nature and have upper and lower channel sections separated by a horizontally aligned web, as shown in FIGS. 2 and 3. However, any design known in the art to provide structural support for load bearing applications, such as I-beams, solid rods and closed channels, may be used as structural members. Chords  11  and  12  are also constructed and arranged to be of a sufficient size and material for supporting the loading estimates of the truss system  10 . Depending on the length of the truss system  10  desired, the chords  11  and  12  may be formed from spliced framing members aligned lengthwise and rigidly connected together by one or more welded connections  29 .  
         [0019]    A plurality of joists  13  rigidly couple the first chord  11  to the second chord  12 , thereby fixing the chord separation distance A. Such joists  13  are adjacent to each other and collectively span approximately the length of the first chord  11 . Joint  13  comprises first diagonal member  14  and a second diagonal member  15 . Diagonal members  14  and  15  are constructed of elongate framing members from any design known in the art to provide sufficient structural support for load bearing applications, such as I-beams, tubular beams, solid rods, and open channels. Also, such members are constructed to be of a sufficient size and material for distributing loads among the structural elements of the truss system  10 , and preferably have a tube-shaped girth of approximately 1{fraction (3/4 )} inches.  
         [0020]    The first diagonal member  14  has upper and lower ends  25  and  26 , respectively, and the second diagonal member  15  has upper and lower ends  27  and  28 , respectively. As shown in FIG. 4, the upper ends  25  and  27  of a joist  13  are coupled together and to the first chord  11  by a second bolted connection  16 . Adjacent joists  13  are coupled together at lower ends  26  and  28  and coupled to the second chord  12  by a first bolted connection  17 , as shown in FIG. 1. Both first and second bolted connections  17  and  16  are comprised of U-shaped joint brackets  22  connected to the first and second chords  11  and  12 , respectively, and to joists  13  by means of a plurality of bolts. The bolted connections  16  and  17  are sized and configured to provide sufficient structural support for transferring forces between the chords and the joists in a load bearing application.  
         [0021]    [0021]FIG. 4 shows the U-shaped joint bracket  22  having a base  30  and flanges  31  extending from the base. The base  30  has at least one hole for receiving a bolt to connect the joint bracket  22  of the second connection  16  to a bottom face  32  of the first chord  11  and to connect the joint bracket  22  of the first connection  17  to a top face  33  of the second chord  12 . At least two holes also extends perpendicularly through both flanges  31 , each receiving a bolt for connecting the joint bracket  22  to either the first or second diagonal members  14  and  15 . Preferably, the joint bracket  22  is constructed and arranged with a size of approximately 20 inches in length, 4 inches in height from the base edge  30  up the flange  31 , and 1¾ inches thick across the flanges  31 .  
         [0022]    Both diagonal members  14  and  15  of a joist  13  are aligned at approximately a 45 degree angle in the vertical plane to the first and second chords  11  and  12  and aligned approximately 90 degrees or perpendicularly from each other. This first diagonal member  14  has a negative slope and the second diagonal member  15  has a positive slope in the vertical plane. Both diagonal members  14  and  15  are connected. Such diagonal members  14  and  15  are constructed and configured such that the first diagonal member  14  angularly subtends approximately 90 degrees with the second diagonal member  15  by means of the second bolted connection  16 . Additionally, the first diagonal member  14  of a joist  13  angularly subtends approximately 90 degrees with the second diagonal member  15  of an adjacent joist  13  by means of the first bolted connection  17 .  
         [0023]    This configuration of the joists  13  partition the first chord  11  into (n) number of upper chord members  19  defined between two adjacent second bolted connections  16  and partition the second chord  12  into (n-1) number of lower chord members  18  defined between two adjacent first bolted connections  17 . Due to these partitions, the first chord  11  is of a length that is approximately one upper chord member  19  greater than the second chord  12 . The joists  13  are also constructed and arranged such that a substantially perpendicular line to the first and second chords  11  and  12  is formed between a centroid of each of the upper chord members  19  and first bolted connections  17 , and between a centroid of each of the lower chord members  18  and second bolted connections  16 .  
         [0024]    Depending on the structural support application to which the truss system  10  is applied, an end support member  21  may be connected to each end of the first chord  11  through one or more vertically aligned bolts, as shown in FIG. 1. The end support member  21 , in turn, is connected to another structural support through one or more horizontally aligned bolts. This allows the loads carried by the truss system  10  to be transferred to the surrounding structure. The end support member  21  is designed from any configuration known in the art to provide support to the end of a load carrying member, and preferably is a bent 90 degree angle configuration with a triangular face plate on one side.  
         [0025]    As shown in FIGS. 2 and 3, a support grid  23  may be utilized to couple adjacent trusses together. The support grid  23  is rigidly connected to the second chord  12  and couples a first truss  34  with a second truss  35  in a horizontal, symmetrically opposed orientation. Metal framing members  24  in a cross configuration connects the second chord  12  of the first truss  34  with the first chord  11  of a second truss  35 , and connects the first chord  11  of the first truss  34  with the second chord  12  of the second truss  35 . The framing members  24  attach to the first chord  11  on the top face  37  and attach to the second chord  12  on the bottom face  36 , as shown in FIG. 3. As shown in FIG. 1, the framing members  24  are horizontally aligned in the longitudinal plane of the truss system  10  with the first and second bolted connections  17  and  16  to maximize the load bearing capabilities of the present invention. The first bolted connections  17  of the first truss  34  and second truss  35  are spaced apart by the support grid  23  a chosen distance for the required stability and load supporting characteristics, and are preferably four to five feet apart. The framing members  24  are preferably constructed from 12 gauge steel and comprise a U-shaped channel with a girth of approximately 1⅝ inches by 3¼ to 4{fraction (7/18)} inches. However, it is the understanding that any design known in the art to provide structural support for load bearing applications, such as I-beams, solid rods, and closed channels, may be used as structural members.  
         [0026]    The present invention may be used in a broad range of applications, such as a structural support for new buildings and as a secondary support system for the retrofit of existing buildings. The present invention may also utilize different components with similar structural and material characteristics to the present components. Further, the dimensions of the current components can be modified as appropriate to enable the present invention to support a desired load. Since certain changes may be made in the above systems and methods without departing from the scope of the present invention, it is intended that all matter contained in the above description or shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.