Abstract:
The present invention is a light steel framed metal joist including an adjustable connector fastened to the joist web that allows one to adjust the length and angle of the joist when attaching to floor and wall systems. The adjustment allows one to install end connectors onto the joists prior to installation while retaining flexibility of orientation during construction. The joist functions in both web bearing and bottom chord bearing configurations. A flat plate distributing member allows one to design a floor system without having to coordinate the positioning of the joist with wall studs. Angle or U shaped members can be fastened to the lower portion of the flat plate distribution member to support joists during construction. The invention further provides a seamless fire stopping system with consideration for acoustic dampening.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This patent application is a National Phase application claiming the benefit of PCT/CA2009/001247 filed on Sep. 8, 2009, in English, entitled ADJUSTABLE FLOOR TO WALL CONNECTORS FOR USE WITH BOTTOM CHORD AND WEB BEARING JOISTS; which further claims the priority benefit from, U.S. Provisional Patent Application Ser. No. 61/136,476 filed on Sep. 8, 2008, both of which are incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to structural members and in particular adjustable connections for use with structural members made from light steel. 
     BACKGROUND OF THE INVENTION 
     The light steel framing market has been improving its floor and wall system products significantly during the past several years. Floor and wall systems have improved to provide better structural performance that allow for simplified installation and provisions for follow up trades. Light Steel Framed walls are sensitive to point loads caused by floor joists, so the connection between the floor system and the wall system is an area where designers often coordinate floor joists to align with the wall studs to accommodate the floor joist end reactions. Coordinating the joists with the studs causes an added complexity for drawing and assembling a structure. Alternatively there are many special shapes that are typically expensive to supply or expensive to install that provide distribution of high floor joist end reactions by distributing the load to multiple studs. A load distribution element allows a designer to place joists between the wall studs so that the joists do not have to be coordinated and located only at wall studs. 
     Given the provision of structurally sound methods for distributing loads from the floor joists to the walls, to be viable it is desirable that the solution meet the requirements incumbent of a complete building system such as acoustic rating, fire stopping, and fire rating. A joist system that is intended for the framing market would be substantially bottom chord bearing or substantially web bearing in order to suit traditional framing protocols. The connection between the floor and the wall entails many design details that should be accommodated to provide a complete floor and wall framing system. The complete floor to wall connection should include as a minimum the following: (1) load distribution capability, (2) a connection that provides flexibility for onsite construction tolerances, (3) fire stopping capabilities, (4) acoustic performance capabilities, (5) provisions for rated sheathing membrane installation, (6) provisions for directly transferring floor diaphragm to the walls, and (7) ease of fabrication, shipping and installation. This invention includes various methods to provide a complete building system approach for a joist system for web and bottom chord framing. 
     SUMMARY OF THE INVENTION 
     In one aspect of the invention there is provided a joist system, comprising: a joist, including: a generally planar steel web having a web face; and at least one elongate chord member extending from the web; a connector, substantially L-shaped in cross-section, including: a connector web portion having a generally planar connector web face, a first end, and a second end; a first connector lip extending from the first end of the connector web that is generally orthogonal to the connector web face; at least one opening in the first connector lip; at least one opening in the connector web, wherein at least one of the at least one opening in the connector web and the at least one opening in the first connector lip is at least one generally elongate opening; wherein the connector is fastened to the joist via at least one fastener inserted into the at least one opening in the connector web. 
     In another aspect of the invention there is provided A connector for use with joist systems, comprising: a connector web portion having a generally planar connector web face, a first end, and a second end; a first connector lip extending from the first end of the connector web that is generally orthogonal to the connector web face; at least one opening in the connector lip; and at least one opening in the connector web, wherein at least one of the at least one opening in the connector web is at least one generally elongate opening. 
     A further understanding of the functional and advantageous aspects of the present invention can be realized by reference to the following detailed description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the invention will now be described, by way of example only, with reference to the drawings, in which: 
         FIG. 1   a  illustrates the prior art floor joist aligned with the stud; 
         FIG. 1   b  further illustrates the prior art floor joist aligned with the stud; 
         FIG. 2  illustrates a prior art floor joist aligned between two studs; 
         FIG. 3  illustrates a prior art balloon framing using track sections; 
         FIG. 4  illustrates three prior art arrangements for distribution of joist loads into wall systems; 
         FIG. 5  is the end of joist resting on bottom chord on a wall; 
         FIG. 6  is the end of joist resting on bottom chord on a beam; 
         FIG. 7  is a web of joist connected to flat plate distribution member; 
         FIG. 8  is a joist framed to a wall via flat plate distribution member from one side; 
         FIG. 9  is a joist framed to a wall from two sides; 
         FIG. 10  is a floor joist attached to a flat plate distribution member, aligned with a stud; 
         FIG. 11  is a floor joist attached to a flat plate distribution member, aligned between two studs; 
         FIG. 12  is a floor joist attached to a flat plate distribution member and a planar gypsum board attached via an angle member with leg down; 
         FIG. 13  is a floor joist attached to a flat plate distribution member and a planar gypsum board attached via a U-shaped member; 
         FIG. 14  is  FIG. 12  with an additional wall board; 
         FIG. 15  is  FIG. 13  with an additional wall board; 
         FIG. 16  is a joist framed to a wall via flat plate distribution member with floor sheathing and an angle at bottom with leg up; 
         FIG. 17  is a joist framed to a wall via flat plate distribution member with floor sheathing, an angle at bottom, gypsum board and extension, and fire protection/acoustic material placed between joists; 
         FIG. 18  is a connector attached to an iSPAN™ joist (see U.S. patent application Ser. No. 10/974,964) 
         FIG. 19  is a connector attached to a C-shape joist; 
         FIG. 20  is the connector; 
         FIG. 21  illustrates adjustment capabilities of slotted connectors, wherein the connector (a) allows for sloped conditions, (b) fully extends, and (c) fully retracts; and 
         FIG. 22  illustrates alternative slotted connectors. 
     
    
    
     SUMMARY OF THE PRIOR ART 
     Typical light steel frame (LSF) construction is based on a number of alternative sized C-Shape members. As shown in  FIG. 1 , wall studs are typically framed into a track section.  FIG. 1(   a ) shows a floor joist  204  aligned with a stud  206  and  FIG. 1(   b ) shows a floor joist  204  aligned at the midpoint between two studs  206 . A problem arises using typical LSF parts because the top track section  202  on a wall cannot support typical joist end reactions. The floor joists  204  are therefore typically framed such that every joist is sufficiently aligned with a wall stud  206  (as shown in  FIG. 1(   a )).  FIG. 1(   b ) illustrates a floor joist  204  positioned between two wall studs  206 . Further, web crippling of the joist member  204 , i.e. failure at the end of a joist due to concentrated loads from bearing, is prevented using bearing stiffeners  208 . The joist is connected to the rim track  210 ; this can be accomplished using a C-Shape bearing stiffener  208  or by additional clips that are installed in situ to accommodate site tolerances, resulting in difficulties with installation and/or increased labor costs. 
     As shown in  FIGS. 2 and 3 , typical LSF parts can be used to provide appropriate distribution, however there are difficulties presented when trying to provide total building system coordination. A balloon framing system can be provided using a track  218  fastened to the wall studs  224  but this presents difficulty for diaphragm transfer and fire stopping installation methods. 
     Applying diaphragm loads at an interior point within the wall height in  FIG. 2 , as introduced in balloon framing, subjects the studs  224  to bending stresses  216  in their weak axis. This requires either (1) the addition of new parts to resist the diaphragm loads at the location of load application or (2) a significant increase in stud weight in order to accommodate the combined action of axial load and weak axis bending (or the combined action of axial load, weak axis bending, and strong axis bending in the case of an exterior load bearing wall). Instead, it is ideal if the diaphragm element, in this case the sheathing  212 , is fastened directly to the vertical shear wall  218  without introducing additional stresses to the studs  224 . As shown in  FIG. 3 , Using a typical LSF track section  218  results in interference  214  (material bunch-up) with the top track  220  of the supporting wall as well as the screws used to fastened the track to the studs (not shown). 
     As shown in  FIG. 4 , various special distribution shapes have been used but highly specialized shapes require large roll formers and present difficulty with coordinating the many alternative floor depths that are used to keep the floor system economical for alternative spans. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Without limitation, the majority of the systems described herein are directed to adjustable connectors for bottom chord and web bearing joist framing. As required, embodiments of the present invention are disclosed herein. However, the disclosed embodiments are merely exemplary, and it should be understood that the invention may be embodied in many various and alternative forms. 
     The Figures are not to scale and some features may be exaggerated or minimized to show details of particular elements while related elements may have been eliminated to prevent obscuring novel aspects. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention. For purposes of teaching and not limitation, the illustrated embodiments are directed to adjustable connectors for bottom chord and web bearing joist framing. 
     To simplify the installation of bottom chord weight-bearing joists in order to suit site tolerances, this invention features an adjustable end connector  10  shown in  FIGS. 5 and 6 . Adjustment allows one to install end connectors  10  on the joists  30  prior to joist installation while retaining the ability to adjust the joist length when installation takes place. 
       FIG. 5  shows the end of a joist  30  resting on the bottom chord  32  on the top track section  36  of a wall.  FIG. 6  shows the end of the joist  30  resting on the bottom chord  32  on a beam  44 . Joists  30  are connected to rim track  50  via connectors  10 . Forces  40  and  42  are illustrative reactions supporting the end of the bottom chord  32  of joist  30 . 
     While  FIGS. 5 and 6  show a joist  30  bearing its load via bottom chord  32 ,  FIG. 7  shows a joist  30  bearing the load via web  34 . To obtain maximum efficiency of a stick framed structure, it is desirable that a method for distribution be such that all matters related to the building system are incorporated. A flat plate system has been invented to satisfy the numerous requirements of a total building system and it is used in conjunction with a web bearing joist. The substantially flat distribution member  46  along with its accessories provides distribution of axial loads from the floor system to the wall. One can add angle  86  or special other shape accessories to help to restrain the flat plate from moving in and out of plane (shown in  FIGS. 12 and 13 ). The special angle  86  or U shapes  86  shown in the sketches provide simple and cost effective methods for installing the rated membrane systems such as gypsum or non-combustible boards that are typically employed with ceiling systems for fire and acoustic ratings. The flat plate  46  can be extended below the floor system to provide a solid and continuous support for the vertical wall rated membrane system. 
     As shown in  FIGS. 8 and 9 , a further embodiment of the present invention is a web bearing joist  30  with a top chord extension  52 . This provides a safe and easy way to drop in place and safely install floor joists on a stick framed wall system. The top chord extension  52  provides an ideal solution for coordinating a concrete floor diaphragm system with a framed wall. An angle  56  can be placed under the end of the top chord where it bears on the wall, helping avoid creating a point load that will overload the wall during construction phase when concrete  54  is being poured into place. The angle  56 , when properly sized, including holes  58  to create shear bond capacity, provides a passive distribution beam for the concrete floor bearing on the wall.  FIG. 9  shows similar joists  30  framed from both sides of studs  38 . The adjustable connector  10  fastens joists  30  to the flat distribution member  53  in  FIG. 8  and the joist  30  to the flat distribution member  53  in  FIG. 9 . 
     As shown in  FIGS. 10 and 11 , the flat plate distribution member  74  allows one to design a floor system without having to align the end reactions with the wall studs, in an economical and technically superior manner. A flat plate member  74  is fastened to wall studs  38  and then floor joists  30  with connectors are fastened to the flat plate.  FIG. 10  shows a floor joist  30  aligned coplanar to a stud  38  and  FIG. 11  shows a floor joist  30  aligned in-between two studs  38 . 
     As shown in  FIGS. 12 and 13 , an angle  86  or a U shaped member  88  can be fastened to the lower portion of the flat plate  84  to support joists  30  during erection. Fastening and connection of the latter components is done via screws, welds, nails, clinching or other means. The plate is stiffened by the angle  86  or U shaped member  88  connected to the bottom and the floor system sheathing or concrete slab floor provide stability to the top. Compartmentalizing this area also allows one to provide seamless fire stopping and acoustic treatments to this critical area. In  FIG. 12 , the joists  30  have gypsum board  82  which is connected to the flat plate  84  via angles  86 . The angle  86  is placed to provide temporary support for the joists  30  during construction and are used to provide a continuous support edge for fastening the edge of the gypsum board. In  FIG. 13 , hat channels  92  hang below and are attached to the underside of joists  30 . The U shaped member  88  allows the gypsum board to be attached continuously along its edge and provides a temporary support for the joists  30  during construction. 
     This invention provides for the continuous support of the ceiling gypsum and wall gypsum as shown in the two embodiments in  FIGS. 14 and 15 . With the addition of an angle  96  or U shaped member  98  at the bottom of the flat plate, this system provides a method to compartmentalize the area between the joists  30  and the area between the underside of floor and the rated membrane  94  on the ceiling system. The angle  96  or U shaped member  98  combined with the flat plate  84  collectively provide a convenient continuous surface to support the rated membrane  94 . The flat plate  84 , when extended slightly below the floor system, provides a continuous surface to terminate and fasten the rated membrane system  95  for the wall. The rated membrane system  95  may be a gypsum or any non-combustible board. 
       FIGS. 16 and 17  illustrate two embodiments incorporating accessories for fire stopping and acoustic considerations. In these embodiments, the floor sheathing  102  restrains the joist  30  and wall track  48  from horizontal displacement. The angle  104  restrains the joist  30  from minor horizontal displacement during assembly. The flat plate distribution member  84  extends below the joist  30  and thus provides a continuous attachment surface for the gypsum board extension  95 . The angle  104  provides a setting shelf for the joists  30 , and creates a confined space between joists  30  for the placement of fire stopping and acoustic rating material  106  between joists  30 , and a surface for the attachment of ceiling gypsum. Material  106  is positioned by friction fit, and then fastened by screws or adhesives or other attachment methods (not shown). 
     When working with metal joists, it is preferable to install the connectors  10  prior to installing each joist  30 . The more preassembly that can be achieved, the more costs can be reduced. The problem with pre-installing the connectors shown in the prior art,  FIGS. 1 through 4 , is that there is no provision for on-site tolerances that are typically experienced. 
     The present invention proposes a connector  10  that includes slotted holes  12  in a number of locations to allow adjustment of the connector to suit site conditions as shown in  FIGS. 18 and 19 . Accordingly this invention provides a floor joist member of adjustable length. A substantially U shaped connector  10  is provided with a stiffening lip  16  and a connector lip  14 . When fasteners  18  are installed in only the slotted holes  12 , the stiffening lip  16  provides a convenient means for tapping the connector in and out. Furthermore, the connector height is selected such that typical minor slopes on roofs and floors can be accommodated by simply rotating the connector within the joist web. 
     The connector may be used on any type of joist.  FIG. 18  shows the connector  10  attached to an iSPAN™ joist  30  (see U.S. patent application Ser. No. 10/974,964) and  FIG. 19  shows a C-shape joist  110 . The connector  10  is isolated in  FIG. 20 .  FIG. 21  shows alternative positions and adjustment capabilities and  FIG. 22  illustrates alternative slotted connector types.  FIG. 21(   a ) highlights the ability to rotate the end connector  10 , thus allowing one to install the joist at an angle to the wall;  FIG. 21(   b ) shows the connecter fully extended;  FIG. 21(   c ) shows the connector fully retracted. 
     As used herein, the terms “comprises”, “comprising”, “includes” and “including” are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in this specification including claims, the terms “comprises”, “comprising”, “includes” and “including” and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components. 
     The foregoing description of the preferred embodiments of the invention has been presented to illustrate the principles of the invention and not to limit the invention to the particular embodiment illustrated. It is intended that the scope of the invention be defined by all of the embodiments encompassed within the following claims and their equivalents.