Abstract:
A metal truss system comprising a pair of chord members of generally U-shaped cross-sectional configuration is joined together by a web formed of a single continuous piece having a wave shape. The apexes of the web are adapted to be received in each chord. The legs of the chords have inwardly recessed portions to form a narrowed throat portion, which provides a stop against which the apex of the web abuts. The resulting positioning of the web apex presents a maximum surface area for welding the web to the chord member. This enables an optimum amount of welding, while minimizing the weakening of the metal being welded. The configuration of the chords and web permits rapid fabrication of the truss.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to materials used in the construction of buildings, and in particular to trusses and joists for supporting roofs, floors, ceilings, walls and decks. More particularly, the invention relates to trusses and joists fabricated from metal. 
         [0002]    There exist numerous truss and joist systems that provide enhanced strength attributes, assembly simplification features, and economies in material and structural composition. The savings in time, effort and money are critical in the construction industry; therefore there is a significant need and demand for truss and joist systems having these traits. While there exist a wide variety of configurations, one common form of truss/joist comprises a pair of elongated chord members joined together by a plurality of web members that span between the chord members. The chord members of this arrangement each comprise a generally U-shaped, integral piece of metal which receive the ends of the web members in the U-shaped portion. The web members are typically secured to the chord members by mechanical means such as screws and rivets, or by welding. Trusses and joists are most economically prefabricated and shipped to construction sites, rather than built as needed at the construction site. While this presents a significant efficiency and cost-saving in construction, it is still imperative that costs of materials be kept as low as possible to be competitive in the industry. The assembly of component parts presents a labor factor that affects the overall cost of the truss/joist. It can take a significant amount of time for the web members to be inserted into, aligned with, and attached to the chord members in manufacturing the truss/joist. Therefore, the manner of assembly of the truss/joist offers an area which can addressed as a way to further lower the cost of materials used in construction. 
         [0003]    Accordingly, it is desirable to provide a low cost metal truss/joist having features which enable rapid assembly, while offering enhanced strength and load capacities 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    There is, therefore, provided in the practice of the invention a metal truss and joist system comprised of a pair of chord members joined together by web members. As used herein, the term “truss” shall commonly refer to both trusses and joists as their respective structures are essentially the same for purposes of the invention. 
         [0005]    In accordance with an embodiment of the present invention, the truss system comprises upper and lower chords joined together by a web. Each chord is generally U-shaped in cross-sectional configuration, and forms a base with legs extending at essentially right angles from either side of the base. The web is generally formed of a single, continuous piece and is formed with waves whose apexes are adapted to be received in each chord. The legs of the chords have inwardly recessed portions at an intermediate position along their lengths, giving the chord a narrowed throat portion at that position. The throat portion provides a stop against which the apex of the web abuts. The depth of the space from the opening in the chord up to the narrowed throat portion allows positioning of the apex of the web so that a maximum surface area of the web is presented for welding to the outer edge of the chord. By increasing the maximum surface area available for attachment of the web to the chord, an optimum amount of welding can be effected, while minimizing the weakening of the metal being welded. 
         [0006]    In accordance with another embodiment of the invention, the truss system comprises a configuration of chords and web which permits rapid alignment in assembly of the truss. 
         [0007]    In accordance with another embodiment of the present invention, each leg of the chord has its end terminating in outward, reversely extending crimped portion. This feature, combined with the recessed portion, provides enhanced strength to the chord. 
         [0008]    Accordingly, it is an object of the present invention to provide an improved truss system. There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
         [0009]    In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
         [0010]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. Though some features of the invention may be claimed in dependency, each feature has merit when used independently. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Further features of the present invention will become apparent to those skilled in the art to which the present invention relates from reading the following description with reference to the accompanying drawings, in which: 
           [0012]      FIG. 1  is a side elevation view illustrating a truss according to a preferred embodiment of the invention. 
           [0013]      FIG. 2  is a cross-sectional view in side elevation of a chord according to a preferred embodiment of the invention. 
           [0014]      FIG. 3  is a cross-sectional view similar to  FIG. 2 , showing the web in cross-section and in phantom. 
           [0015]      FIG. 4  is a partial view of the truss system, showing the insertion of the apex of a web inserted into a chord. 
           [0016]      FIG. 5  is a view similar to  FIG. 4 , showing the web as being welded to the chord. 
           [0017]      FIG. 6  is a side elevation view illustrating a truss according to another embodiment of the invention. 
           [0018]      FIG. 7  is a perspective view of another embodiment of the truss system. 
           [0019]      FIG. 8  is a perspective view of the truss system support member. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    An embodiment of the present inventive truss system  10  is illustrated in  FIG. 1 . It is comprised of upper chord  12 , lower chord  14  and web member  16 . The configuration of upper chord  12  and lower chord  14  are similar, except for being oriented opposite of each other. Therefore, for efficiency in explanation, the description of chord  12  herein will be equally applicable to chord  14 . As shown in  FIG. 2 , chord  12  has a generally U-shaped cross-sectional configuration, and is comprised of a base portion  18  and leg members  20  and  22 . Leg members  20  and  22  extend at substantially right angles from base portion  18 . Chord  12  is optimally formed from a single piece of metal, preferably around 14-18 gauge, which can be bent into the prescribed shape. Each of leg members  20  and  22  is formed with an inward recessed portion  24  and  26 , respectively, at an intermediate position thereof, which extends along the entire longitudinal span of the chord. Recessed portions  24  and  26  oppose and approach each other within the chord to form a narrowed throat portion  28 . The lower ends of recessed portions  24  and  26  form shoulders  30  and  32 , respectively, which provide a partial boundary between chord opening  34  and interior chamber  45  of chord  12 . Preferably, shoulders  30  and  32  have a substantially orthogonal shape. As shown in  FIG. 3 , interior chamber  45  also provides a compartment for receiving a reinforcing element  47 , such as a steel tube or bar, for strengthening the chord. The reinforcing element  47  is held within interior chamber  45  by upper shoulders  29  and  31  of inward recessed portions  24  and  26 , respectively, as shown in  FIG. 3 . Reinforcing element  47  is an elongated piece that can be inserted into an open end of the chord member and pushed down along the interior of the chord member a desired distance. The length of reinforcing element  47  can be coterminous with the chord member, or a shorter length, depending on the strength requirements necessary. Reinforcing element  47  may be held in place within interior chamber  45  through plug welds. 
         [0021]    Web member  16  is formed of a single piece and is bent into repeating wave sections, and is adapted to span back and forth between chord members  12  and  14  as shown in  FIG. 1 . Web member  16  is optimally formed of metal tubing, which can be either square or rectangular. The cross-width  33  of web member  16  closely approximates the dimension of chord opening  34  as shown in  FIG. 3 . Shoulders  30  and  32  act as stops against the square corners of web member  16  to limit the depth to which web member  16  is inserted into the chord as shown in  FIG. 4 , and provide a guide for assembling the truss system. The back-and-forth bending of web member  16  creates a series of apexes  36  which are introduced into chords  12  and  14  as shown in  FIG. 1 . The area provided by chord opening  34 , as limited by narrowed throat portion  28 , permits sufficient introduction of apex  36  so that its meniscus  38  lies substantially along the ends  40  of leg members  20  and  22  as shown in  FIG. 4 . This maximizes the available area of web member  16  against which to weld for securing to the chord as shown in  FIG. 5 . While single-piece (non-continuous) web members placed at an angle would present a greater surface area for welding than a single piece placed at right-angles to the chord, it is nevertheless undesirable to utilize that entire surface because excessive welding, and the heat it generates, can create distortions in the components. Such distortions will actually weaken the web member substrate which can result in truss failure while under a load. Accordingly, the larger surface area provided by placing the meniscus  38  along the ends  40  of the leg members  20  and  22  permits multiple, discrete welding points  42  without having to weld across the entire point of contact as shown in  FIG. 5 . The use of short welds reduces the intensity of the heat, thereby lessening the potential for distortions in the component material. Thus, a stronger connection is made between web member  16  and chord  12 , while minimizing substrate degradation from welding. 
         [0022]    The configuration of the chords and web member permits the fabrication of trusses to occur more quickly. The channel provided by the narrowed throat portion  28  of chord  12 , and the stop point provided by shoulders  30  and  32 , enable quick insertion and placement of web member  16  into the chord. The continuous, single-piece wave form web member  16  is relatively self-aligning due to the narrowed throat portion against which it engages. Web member  16  is simply pushed up into the chord until it engages against shoulders  30  and  32 , as shown in  FIG. 3 , which automatically positions the meniscus  38  along ends  40  of leg members  20  and  22  where welding is made. The wave angle of the web member is fixed, so it is unnecessary to adjust the angle of insertion of the web member within the chord. Further, welding of the web member to the chords can be done in one consolidated process, rather than serially where each individual member would have to be first positioned and aligned and then welded. As such, the assemblage of the truss can be carried out by an automated assembly line process. Thus, a tremendous time-savings in truss construction is made possible. Measurements for the proposed truss can be made in advance of the assembly, so that the proper dimensions of the web member can be prepared. The invention is equally applicable in the construction of triangular trusses, whose upper and lower chord members lie transversely to each other as shown in  FIG. 6 , and is not limited to trusses whose chords are aligned parallel. 
         [0023]    A preferred embodiment of the chord&#39;s structure comprises a width at the base portion  18  being 1.716 inches, a height of 4.00 inches, and a width of 1.50 inches at throat opening  34 . Each recessed portion  24  and  26  is 0.75 inches in height, and are positioned opposite each other in the chord at a distance of 1.00 inches. Each of ends  44  and  46  of leg members  20  and  22  are bent back outwardly to lie back against the chord as shown in  FIG. 2 . This provides an additional thickness at the leg ends of the chord to provide stiffening and strength thereto. Each of ends  44  and  46  are 1.00 inches long. Each of shoulders  30  and  32  extend into throat opening  34  a distance of 0.25 inches. 
         [0024]    Another embodiment of the inventive truss system comprises a support member for receiving and supporting a terminal end of the top chord when erected. A truss is typically supported on a wall stud support  100  by being secured to a top beam  102  of the wall stud support as shown in  FIG. 7 . By means of the present embodiment of the invention, a support member  104  is adapted for securing to the top of beam  102  of the wall stud support  100  and which is received within the inner chamber of the top chord  12  for supporting the truss on top of the wall stud support  100 . 
         [0025]    Support member  104  is further shown in  FIG. 8  and comprises a rectangular shaped member  106  whose height h approximates the internal depth of top chord  12  and whose thickness t approximates the width of narrowed throat portion  28  of top chord  12 . The width w of support member  104  may be around a few inches. Rectangular shaped member  106  is vertically supported on base plate  108  by welding or the like. Alternatively, member  106  and base plate  108  may be integrally formed as one piece. A series of bolt holes  110  may be provided in base plate  108  by which support member  104  may be bolted to top beam  102  of the wall stud support. Alternatively, base plate  108  may be welded to top beam  102 . 
         [0026]    Support member  104  provides a simple connection point for placing a terminal end of chord  12  for support on wall stud support  100  as shown in  FIG. 7 . The respective dimensions of support member  104  and chord  12  are such that chord  12  is simply placed over and onto support member  104 . The recessed wall portions  24  and  26  of chord  12  closely engage support member  104  and fasteners  112  (such as screws) can be used to secure chord  12  to the support member  104  at the areas where wall portions  24  and  26  engage chord  12 . Support member  104  helps to stabilize and hold the truss in its vertical orientation. A support member  104  would be provided for each terminal end of an individual truss. 
         [0027]    Another advantage provided by support member  104  is that it makes erection of the structure using the truss system simpler by providing an alignment guide. By placing the support members at the appropriate spaced apart distances on the top beam  102  of the wall stud support, workers can more quickly and accurately connect the trusses to the wall stud support. A further advantage is that the overall height of the erected structure may be reduced because the connecting the top chord, instead of the bottom chord, to the top beam of the wall stud support lowers the effective height of the erected truss by a few feet. 
         [0028]    From the above description of preferred embodiments of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims. 
         [0029]    The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.