Abstract:
The present invention is directed towards improved apparatuses and methods for connecting a structural bracing system having a first geometry to a structure or structural component having a second geometry.

Description:
CROSS-REFERENCE 
       [0001]    This application claims the benefit of the priority of presently pending Provisional U.S. application No. 61/468,949, filed Mar. 29, 2011, entitled “Geometric Connecting Assembly and Method for Braced Frame Connections”, and is incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is directed towards improved apparatuses and methods for the connection of a structural bracing system to a structure. 
       BACKGROUND 
       [0003]    Braces of many types, including, but not limited to budding-restrained braces are used as part of lateral load-resisting systems for earthquake and wind resistance of structures (buildings, bridges or other types of structures). They are most commonly used in diagonal configurations between building stories, however, other configurations/orientations are possible. Braces for building structures may be used in many different forms, such as, for example, braces used in concentric and non-concentric bracing systems. Braces used in structural construction are often square or rectangular tube, or round pipe sections. Other types of braces use rolled sections (I-shapes or angles). Many types of structural brace elements are known. For example, buckling-restrained braces may have an outer steel shell and an inner steel component with a material such as a concrete, cement, or other material of varying elasticity interposed between the two steel components. In the case of braces comprising tube or pipe outer sections, the connection between the brace element and the frame structure of, for example a building or bridge, etc., is usually made by slotting the end of the tube (or pipe) to allow it to fit over a gusset plate, and then connecting the tube to the gusset to complete the connection. 
         [0004]    A gusset plate is a flat plate located at the intersection of a frame of a structure, such as, for example, a beam and/or column. The gusset plate may be welded along its edge at the beam and column. The primary function of the gusset plate is to provide a connection point to the structural framing system and is commonly used for diagonal bracing systems. However, the end of a brace may often comprise a multi-planar geometry, such as, for example, a cruciform cross-section, and the gusset plate on the main structure to which the brace attaches is typically a flat plate occurring in a substantially singular plane. In the past, according to known configurations, bolted connections between a cruciform cross-section brace and a gusset plate have required the addition of a series of separate rib plates connected to the gusset plate to create a cruciform cross-section on the gusset, substantially similar in shape to the brace end. Additional splice plates are then bolted onto the gusset and onto the brace to establish the connection therebetween. 
         [0005]    Many types of connections between cruciform brace ends and gusset plates with rib plates are known. One such connection comprises groove-welding in the interface between the brace end and the gusset. This type of welding is difficult to perform in the field, and combined with the angular installation of the brace, and considering required tolerances for this special type of weld, such a connection is time-consuming, difficult, requires additional multiple parts such as wing, or side plates to build-up the gusset, and is otherwise not preferred for use in practice. Another type or connection comprises the presence of a slot in the gusset plate, with one horizontal leg of the brace cruciform end placed in the gusset slot until the vertical legs of the cruciform adjoin the gusset plate. Weld metal is then placed around the edges of the vertical surface of the brace cruciform end to connect it to the gusset. This configuration is also a time-consuming, difficult to perform, and involves a number of structural compromises that are undesirable. Another type of known welding comprises the welding of multiple plates or angle sections between the cruciform brace end and the cruciform cross-section on the gusset. This configuration is also time-consuming, difficult to perform, and involves a number of structural compromises that are undesirable. Additionally, such joining of brace elements to a structural frame in the field is labor-intensive and requires maintaining a large inventory of custom fittings uniquely identified to the type of brace being used. A cost-effective and less labor-intensive method of joining braces and brace elements to structural frames that is also more universal or standardized would be particularly advantageous. 
       SUMMARY OF THE INVENTION 
       [0006]    Embodiments of the present invention are directed to methods for connecting a structural brace to a building frame comprising the steps of providing a brace having an end comprising a geometric mating surface, and providing a connector for one or multiple parts, such as a geometric connecting assembly (GCA), comprising a first end having a mating component comprising a geometric shape that is substantially complementary to the geometric mating surface of the brace, such that the geometric mating surface of the brace end is insertable and receivable into the substantially complementary geometric shape of the connector mating component. The connector has a second end pre-selected and dimensioned to engage a frame support. A frame support is provided comprising a surface dimensioned to engage the second end of the connector. The connector is then connected to the frame support, and the brace is connected to the connector. 
         [0007]    The geometric shape of the connector mating component may be any desired geometric shape, but is preferably selected from the group consisting of: curved, linear, box-shaped, I-shaped, x-shaped or star-shaped, intersecting diagonals, and “arrow-shaped”, continuous or interrupted geometries, and combinations thereof, with a geometry suited to receive a cruciform shape being particularly preferred. It is understood that the term “cruciform” encompasses all cross-shaped geometries including those where the intersecting lines are and are not equidistant, and the intersecting lines may intersect each other at angles that create angles at their intersection of more than, less than or equal to about 90°. 
         [0008]    According to further embodiments, the present invention is directed to an apparatus for connecting a structural brace to a building frame comprising a brace having an end comprising a geometric mating surface and a connector comprising a first end having a mating component comprising a geometric shape that is substantially complementary to a geometric mating surface of a brace, such that the geometric mating surface of the brace end is insertable and receivable into the substantially complementary geometric shape of the connector mating component. The connector has a second end pre-selected and dimensioned to engage a frame support. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The objects and advantages of the embodiments of the invention will become more readily apparent to those of ordinary skill in the field after reviewing the following detailed description and accompanying drawings wherein: 
           [0010]      FIG. 1  is a perspective close-up view of one embodiment of the invention showing a cruciform-ended brace connected by a GCA to the gusset plate; 
           [0011]      FIG. 2  shows a second view of the embodiment of  FIG. 1 ; 
           [0012]      FIG. 3  shows a further variation of the embodiment of  FIG. 1 , wherein the GCA end closest to structural frame is tapered and closed, and the GCA end closest to the brace end is open; 
           [0013]      FIG. 4  shows a variation of the embodiment of  FIG. 3 , wherein the GCA end closest to the structural frame is tapered and closed, and the GCA end closest to the brace end is closed; 
           [0014]      FIG. 5  is a further perspective close-up view of another embodiment of the invention showing a brace of cruciform cross-section connected by a GCA to the gusset plate; 
           [0015]      FIG. 6  is an exploded view of the assembly shown in  FIG. 5 ; and 
           [0016]      FIGS. 7   a  and  7   c - 7   g  show illustrative configurations for the geometric shapes of GCA alternative to the box-shape of  FIG. 7   b  and illustrated in  FIGS. 1-6 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Embodiments of the GCA of the present invention are significant improvements over known structural connection concepts, namely, the slotting of a closed prismatic section, by using a selectively dimensioned segment or segment, preferably “built-up from two component parts, to facilitate the attachment of a brace to a structural frame, such as, for example, a gusset plate. The built-up section or sections form an adapter that is specifically dimensioned to universally connect the brace having a first geometric configuration (typically in multiple planes) to a building support structure having a second geometric configuration different from the first configuration (typically in one plane). According to preferred embodiments of the present invention braces with cruciform cross-sections are connected to a gusset plate at each end of the brace using the GCA of the present invention to transfer the force from the brace to the building frame. 
         [0018]    According to still further embodiments of the present invention, one function of the current invention is to connect a bracing member to a structural frame. It is understood that the structural frame is one that may be found in any structure such as, for example, buildings, bridges, open structures such as a hangars, and any industrial structure that may or may not be designed for occupancy. For cruciform cross-section braces, the GCA provides greatly enhanced stability against in- or out-of-plane bending or buckling for brace compression loads, such as, for example, those that occur under earthquake or wind lateral loading on a structure, both for the end of the brace and for the gusset plate itself. For a brace with a GCA connection, compared to, for example, the known cruciform brace connection types described above, the bending moment of inertia of the connection region is of the order of about  3  to about  5  times greater. 
         [0019]      FIG. 1  shows one embodiment of the present invention. A connection assembly  10  is shown. Gusset plate  12  is connected to or is an integral part of building support  14 . A GCA  16  is connected to gusset plate  12 . Brace  18  has cruciform connecting end  20  engaging and connected to GCA  16 .  FIG. 2  is a reverse angle view of  FIG. 1 . 
         [0020]      FIG. 3  shows an embodiment of the present invention where GCA  16  comprises a tapered end  22  engaging gusset plate  12 . In  FIGS. 1-3 , GCA  16  has an open end  24 .  FIG. 4  shows an embodiment where GCA  16  has a top plate  26  having a negative cruciform cut into top plate  26  and into which brace cruciform connecting end  20  is inserted. It is understood that top plate  26  may be constructed from numerous separate plates joined together to form the top plate  26 . As such, it is understood that end  20  is secured at top plate  26 , including scenarios where end  20  is brought to a particular orientation first, and top plate  26  is built-up around end  20 . 
         [0021]    According to one embodiment of the present invention, as shown in  FIG. 5 , an end of a cruciform-ended brace  50 , which may include a buckling-restrained brace (not shown), is shown in position engaging the geometric (in this instance, box-shape, configured to receive a cruciform shape) end of the GCA  52  of the present invention. The end of the brace  50  that engages the GCA  52  is configured to mate with the substantially complementary geometric shape of the GCA  52 . In this way, a length of the cruciform end of the brace  50  is inserted into, and otherwise engages the GCA  52  in a mating orientation. The mating end of the brace  50  and the GCA  52 , therefore, have cruciform and negative cruciform cross-sections, respectively. 
         [0022]      FIG. 6  is an exploded view of the structure shown in  FIG. 5 . As shown in  FIGS. 5-6 , according to one embodiment of the present invention, in the case of a cruciform cross-section brace, the slot in the brace end of the GCA is adjoined to the cruciform end of the brace and the GCA and brace are connected together by welding.  FIG. 6  shows the two C-shaped components of the GCA,  52   a  and  52   b.  When components  52   a  and  52   b  are positioned relative to each other to form a negative geometric opening at end  58  that is preselected to substantially match the dimension and geometry of the gusset plate  54  into which the GCA will fit. The GCA components  52   a  and  52   b  are then preferably connected to the gusset  54  by welding. In addition, when components  52   a  and  52   b  are positioned relative to each other to form a negative geometric opening at end  56  that is preselected to substantially match the dimension and geometry of the brace end  60  allowing the brace end  60  to engage the GCA component. 
         [0023]    According to one preferred embodiment, to connect the GCA components  52   a  and  52   b  to the brace end  60 , edges A of  52   a′  and  52   b  are adjoined to edge A′ of brace end  60 . Slots B of  52   a  and  52   b  are positioned over edge B′ of brace end  60  and edges C of  52   a  and  52   b  are adjoined to edge C′ of brace end  60 . Further, the GCA components  52   a  and  52   b  are adjoined to the gusset plate  54  by adjoining edges D of  52   a  and  52   b  to regions D′ of gusset plate  54  (region D′ is on both sides of gusset plate  54 ) and similarly by adjoining edges E of  52   a  and  52   b  to region E′ of gusset plate  54  (region E′ is on both sides of gusset plate  54 ). 
         [0024]    It is further understood that the presence of the two “C-shaped components”  52   a  and  52   b  may be obviated by providing a singular GCA component, or more than two components that have been designed and dimensioned to receive the brace, in geometric, and substantially complementary fashion, while also fitting onto the gusset of a structural frame, or the structural frame itself. 
         [0025]    It is also understood that any geometry may be used, in addition to cruciform, that is structurally advantageous in terms of resistance to in- and out-of-plane bending, load/force transfer, etc., or that may be desired for ease of assembly or architectural reasons. Other embodiments are further contemplated by the present invention, including the use of GCAs having a geometry complementary with braces having cross-sections such as, for example, curved, linear, box-shaped, I-shaped, x- or star-shaped, intersecting diagonals or “arrow-shaped”, continuous or interrupted geometries, etc. Non-limiting, illustrative geometries are shown in  FIGS. 7   a - 7   g.  As mentioned above, in these embodiments, and alternatively, also for the case of a cruciform cross-section brace, the GCA may comprise a single tube section, rather than multiple components that can be oriented together to best join a brace end to a structural frame. For example, as shown in  FIG. 6 , two “C-shaped” components, with appropriate slots provided are dimensioned to accept the geometric form of the brace cross-section at one end of the GCA, and the gusset section at the other end of the GCA. 
         [0026]    Therefore, according to one embodiment, the GCA has a slotted end opposite the cruciform end for engaging with a frame structure component, such as, for example, a gusset plate. Though not shown, it is understood that the gusset plate represents the feature by which the brace is connected to the structure to be supported via the GCA. Therefore, embodiments of the present invention further contemplate attachment of braces via the GCA directly to the structural frame, even in the absence of a specific gusset. 
         [0027]    Further, embodiments of the present invention allow for significantly larger forces to be transferred from a cruciform-ended brace to the building frame as compared to other known welded connection configurations. For lower-force braces, the present invention further contemplates that the tube portions of the GCA can be made, for example, from split hollow steel sections, and for larger-force braces the tube portions of the GCA can be fabricated from steel plate pieces to form a built-up section. Embodiments of the present invention also allow for the casting of the GCA to achieve desired geometric connecting pieces and architectural details. The GCA can be fabricated from any steel, or metallic alloy, that provides sufficient strength and stiffness properties for the application, such as, for example, ASTM Grade A500, A501 and A53, etc., with ASTM Grade A 500 being particularly preferred for a GCA comprising hollow steel sections; and also ASTM A36, A572, A913, A992 and A1043 for GCA built-up sections, with ASTM A36 and A572 being particularly preferred; and ASTM A958 being particularly preferred for GCAs comprising cast shapes. 
         [0028]    According to one embodiment of the present invention, as shown in  FIGS. 5 and 6 , an end of a cruciform-ended brace, which may include, for example, a buckling-restrained brace, is shown in position engaging the geometric (in this instance, box-shape, configured to receive a cruciform shape) end of the GCA of the present invention. The end of the brace that engages the GCA is configured to mate with the substantially complementary geometric shape of the GCA. In this way, a length of the cruciform end of the brace is inserted into, and otherwise engages the GCA in a mating orientation. The mating end of the brace and the GCA, therefore, has cruciform and negative cruciform cross-sections, respectively. It is further understood that any geometry may be used, in addition to cruciform, that is structurally advantageous in terms of resistance to in- and out-of-plane bending, load/force transfer, etc., or that may be desired for ease of assembly or architectural reasons. Such alternative geometries are illustrated in  FIGS. 7   a - 7   g  for non-limiting and non-comprehensive purposes. 
         [0029]    There are various possible methods that may be used to connect (e.g. attach, etc.) the GCA component, or components, to the brace end and to the gusset plate. For example, the GCA component, or components, may be attached to the brace ends by welding, at a location remote from the building construction site. The brace, with GCA components attached, may be subsequently welded to, for example, the gusset plate at the building construction site, etc. 
         [0030]    No specific welding technique is required according to the present invention, and the methods employed may depend only on the structural building code having jurisdiction in the region of intended use. Useful non-limiting welding techniques may include, for example, GMAW, SMAW, FCAW, SAW, EGW and ESW, as would be readily understood by one skilled in the welding field. 
         [0031]    To facilitate welding of the brace and GCA to the gusset plate at the building site, various temporary support features may be provided on the brace, gusset and on the GCA, or any combination thereof, to facilitate positioning of the GCA before welding it to the gusset plate and brace. These may include features, such as, for example, holes or temporary support seats, etc. 
         [0032]    It is further understood, and further embodiments of the present invention contemplate, that the GCA may be designed to connect any brace element, especially a brace element end having multi-planar geometry to a support frame element, such as for example, a gusset having single- or multi-planar geometry. The desired connecting method comprises not only welding, but any attaching or connecting means that will suitably join a brace element to a support structure of a building, such as, for example, a building frame. Such connecting means include bolting, riveting, or use of any suitable fastening means designed to provide the required strength, stability and resistance to in-and out-of-plane bending of the brace end, connection region and gusset plate, while allowing control of the cross-sectional dimensions of the connection region in the design process, to meet architectural design requirements, local building standards and codes, etc. 
         [0033]    Therefore, embodiments of the present invention contemplate many unique features of the GCA such as, for example facilitating attachment of a brace member having a multi-planed end to a flat (single-planed) frame or multi-planed support feature, such as, for example, a gusset plate. In a preferred embodiment the multi-planed end of the brace is cruciform in shape. 
         [0034]    Still further, embodiments of the present invention contemplate facilitating the connection of brace and gusset plate parts of dissimilar thickness, dimension and/or geometry. This is accomplished by, for example, varying of the width of the slots along the longitudinal length of the GCA, and varying the geometry on each end of the GCA. According to one embodiment, the present invention obviates the need for bolts or pins, as the components are preferably welded. 
         [0035]    If desired, all welds for the attachment of the GCA to the brace, and the GCA to the gusset plate, can be fillet welds; among the easiest and most economical weld used in building structure construction. A fillet weld is understood to be a weld used to join two parts of steel with surfaces to be welded often oriented at approximately right angles to each other, to make lap joints, corner joints, or T-joints. Other types of welds may be used, including groove-welds of the partial or full penetration type. 
         [0036]    As mentioned above, the GCA configurations of the present invention therefore provide high-strength and a high-bending stiffness for superior stability and resistance to in- and out-of-plane bending of the brace end, connection region and gusset plate, while allowing control of the cross-sectional dimensions of the connection region in the design process, to meet architectural design requirements. This is possible because the GCA does not necessarily comprise a single pre-defined cross-sectional shape. Rather, the size, shape and thickness of the GCA component parts can be selectively designed and dimensioned to achieve strength, stiffness and architectural design objectives. As a result, the GCA configuration allows greater flexibility in the cross-sectional dimensions of the brace cruciform end (than with conventional known connections), to meet architectural design requirements. One example of this flexibility is that the dimension of the cross section of the cruciform is not dictated by dimensions previously required, such as, for example, bolting. In addition, according to still further embodiments of the present invention, the GCAs are understood to facilitate connecting braces to structural frames, including frames that may or may not have structural connecting features, such as, for example, gussets. In this way, the GCAs of the present invention also contemplate connecting braces and brace assemblies directly to structural frames. 
         [0037]    As stated above, the present invention allows many variations in the geometric shape and form of the connection (such as tapers, and closed forms), and thus provides for greater architectural design opportunity, such as, for example, greater variations in the geometric shape and form of the brace tube and the tube connection portion when built-up sections are used. This allows greater architectural design opportunities, different weld configurations, and consequently more manufacturing options. Some illustrative configurations are shown in  FIGS. 7   a - 7   g.    
         [0038]    Numerous other aspects of embodiments, embodiments, features, and advantages of the present invention will appear from the following detailed description and the accompanying drawings. In the description and/or the accompanying drawings, reference is made to exemplary aspects of embodiments and/or embodiments of the invention which can be applied individually or combined in any way with each other. Such aspects of embodiments and/or embodiments do not represent the full scope of the invention. Reference should therefore be made to the claims herein for interpreting the full scope of the invention.