Abstract:
A connection apparatus includes a frame-side member securable to a steel structural frame, a brace-side member securable to a seismic brace, and a coupling element that secures frame-side and brace-side members to each other. By way of example, the connection element may provide a hinge-type connection, which substantially isolates a seismic brace from nonaxial loads. As another example, the connection element may be a ball-and-socket type connection, which substantially isolates a seismic brace from nonaxial loads and absorbs any shear and moment applied thereto when the seismic brace drifts out of an intended plane of the steel structural frame. The connection element may also include a collar to stabilize the brace-side member and prevent shears and moments from causing the same to buckle in an unintended direction. Methods of installing and using the connection apparatus are also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation of application Ser. No. 10/310,692, filed Dec. 5, 2002, now U.S. Pat. No. 6,837,010, issued Jan. 4, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates generally to connection apparatus for use with seismic braces. In particular, the present invention relates to connection apparatus which prevent seismic and gravitational loads on steel structural frames from being applied nonaxially to seismic braces. By way of example, the connection apparatus may allow the brace to pivot relative to a structural frame.  
         [0004]     2. Background of Related Art  
         [0005]     In many areas of the world, particularly seismically active areas, large buildings and other structures may be subjected to seismic loads. In order to prevent structures from being damaged by seismic loads, particularly the vibrations that follow the application of seismic loads to structures, or to at least reduce the amount of damage that seismic loading may cause to such structures, various shock-absorption devices have been developed.  
         [0006]     One such shock absorption device, which is useful with steel structural frames, is commonly referred to as a “seismic brace.” As shown in  FIG. 1 , a pair of seismic braces  10  is often arranged within each “bay”  32  of a steel structural frame  30 , each bay  32  typically being formed by an adjacent pair of substantially horizontally oriented steel beams  34  (e.g., beams  34   u ,  34 L shown in  FIG. 1 ) and an adjacent pair of substantially vertically oriented steel columns  36 . Bottom corners  38  of each bay  32  are formed at junctions between a lower substantially horizontally oriented steel beam  34 L and the substantially vertically oriented steel columns  36  at each side of bay  32 . Lower ends  12 L of seismic braces  10  are typically secured at opposite bottom corners  38  of bay  32 . Upper ends  12   u  of seismic braces  10  are typically secured to an upper substantially horizontally oriented steel beam  34   u  at adjacent, substantially central locations thereof. As such, the two seismic braces  10  within a bay  32  of steel structural frame  30  are arranged in an inverted “V” configuration. Other, similar arrangements of seismic braces are also known, including “V” configurations, alternative “V” and inverted “V” configurations, a single, diagonally oriented seismic brace  10  in each bay  32  and another, oppositely oriented seismic brace  10  in the next laterally adjacent bay  32  (i.e., such that seismic braces  10  in two adjacent bays  32  form a “V” or inverted “V”), and the like. By arranging seismic braces  10  in this manner, when a seismic, or earthquake, load is applied to the structure of which steel structural frame  30  is a part, typically by shearing bay  32  in the directions of arrows  40  and  42 , one seismic brace  10   a  of a pair will be subjected to a compressive load, depicted by arrows  44 , while a tensile load, illustrated by arrows  46 , will be applied to the other seismic brace  10   b.    
         [0007]     Conventionally, seismic braces have been rigidly secured to the beams  34  and/or columns  36  of steel structural frames  30 .  FIGS. 2 through 2 B illustrate an exemplary conventional connection, which includes the use of planar gusset plates  15  that are welded into place relative to a beam  34  and/or a column  36  and which have perpendicular extensions  16  welded to each side thereof. As shown in  FIG. 2A , a cross-section taken perpendicular to the planes of both gusset plate  15  and extensions  16  thereof has a generally cruciform shape and, thus, four interior corners  17 . Thus, each gusset plate  15  is configured complementarily to the exposed end  12  of a yielding core  11  ( FIG. 1 ) of a seismic brace  10  ( FIG. 1 ), which also typically has a cross-section, taken transverse to the length thereof, that is generally cruciform in shape and, thus, includes four interior corners  13  that extend along the length thereof, as shown in  FIG. 2B . The cross-section of an exposed end  12  of a yielding core  11  of a seismic brace  10  and the corresponding features of the cross-section taken through gusset plate  15  and extensions  16  thereof may have substantially the same dimensions. A rigid connection between these two elements is typically effected by way of intermediate securing elements  19 , which are typically referred to as “splice plates,” positionable across portions of both an exposed end  12  and a gusset plate  15 /extension  16 , within corresponding interior corners  13  and  17 . Each intermediate securing element  19  includes apertures  20 ,  21  formed therethrough, which respectively align with corresponding apertures  14  formed through exposed ends  12  of yielding core  11  and apertures  18  formed through gusset plate  15  and extensions  16  therefrom. Apertures  14 ,  18 ,  20 , and  21  are typically configured to receive bolts  22 , which, along with complementarily threaded nuts  23 , secure intermediate securing elements  19  in place with respect to both gusset plates  15  and exposed ends  12  of yielding core  11 , thereby securing seismic braces  10  into place relative to steel structural frame  30 .  
         [0008]     A seismic brace  10  ( FIG. 1 ) is secured to a steel structural frame  30  by aligning exposed ends  12  of a yielding core  11  ( FIG. 1 ) of each seismic brace  10  with a corresponding gusset plate  15  that has already been secured to one or more of a beam  34  and/or a column  36  of steel structural frame  30 , as well as with extensions  16  that have been secured to that gusset plate  15 . Intermediate securing elements  19  are then positioned within interior corners  13  and  17 , then bolted (e.g., with bolts  22  and complementarily threaded nuts  23 ) to gusset plate  15 , extensions  16  therefrom, and exposed end  12 . As shown, the connection of exposed ends  12  to gusset plate  15  is typically established by way of four intermediate securing elements  19  which have L-shaped cross-sections, taken transverse to the lengths thereof.  
         [0009]     Referring again to  FIG. 1 , in addition to applying loads axially to seismic braces as a result of the shear generated by seismic and gravitational loads, rigid connections of this type typically transfer additional shears and moments, which are generated as a seismic brace  10  drifts laterally. Application of shear and moment to a yielding core  11  of a seismic brace  10  along vectors which are not located in a plane of bay  32  undesirably causes a bending moment and shear stress to be applied to yielding core  11 , which, along with compressive loads applied thereto, results in a so-called “combined stress” that is greater on one side of yielding core  11  than on the other and that may cause seismic brace  10  to buckle in an unintended direction. When such buckling occurs, seismic brace  10  is no longer useful for either shock absorption or structural support.  
         [0010]     Thus, a connection apparatus which substantially isolates a seismic brace from nonaxially oriented loads, as well as that reinforces or isolates the seismic brace from shears and moments that occur as a seismic brace drifts from a plane of a bay of a steel structural frame in which the seismic brace is located, would be an improvement over the existing art of which the inventors are aware.  
       SUMMARY OF THE INVENTION  
       [0011]     A connection apparatus according to the present invention includes a first member, or frame-side member, which is configured to be secured to a structural frame, a second member, or brace-side member, which is configured to be secured to a core member of a seismic brace, and a coupling member. The frame-side member and brace-side member both include coupling elements which are configured to receive or to be received by complementary portions of the connection member.  
         [0012]     In an exemplary embodiment, the frame-side member of the inventive connection apparatus may comprise a substantially planar gusset plate. The gusset plate of the frame-side member is configured to be welded into a corner formed at a junction between two structural steel frame members. The gusset plate includes an aperture, which is substantially circular in shape, formed therethrough. The brace-side member may include two knife plates which are spaced apart from one another a sufficient distance that the gusset plate may be interleaved therewith. Both elements of the brace-side member also include apertures, which are in alignment with one another and alignable with the aperture of the frame-side member. The apertures of the elements of the brace-side member may have substantially the same size and configuration (e.g., substantially circular) as the aperture of the frame-side member. Upon assembly of the frame-side and brace-side members with the apertures in substantial alignment, the coupling member, which may have a substantially cylindrical central section, may be introduced into the apertures and secured in place relative to the frame-side and brace-side members, thereby coupling the frame-side and brace-side members of the connection apparatus to one another.  
         [0013]     The coupling member of the connection apparatus may be held in place by way of enlarged heads at the ends thereof, bent regions at the ends thereof, securing elements that extend through apertures near the ends thereof, transversely to the length of the coupling member (e.g., like cotter pins), or by other position-retaining means.  
         [0014]     The knife plates of the brace-side member are secured in place relative to a load-bearing member, or “core,” of a seismic brace. For example, the knife plates may be welded directly to the core or to an intermediate member which is, in turn, welded to the core. These arrangements facilitate the positioning of an end of a yielding core closer to the structural steel frame than do conventional, rigid connections, which typically consume a significant portion of the fixed distance between brace connection locations. Thus, connection apparatus according to the present invention may facilitate the use of seismic braces which include yielding cores that are longer than the yielding cores of conventional seismic braces that may be used at the same location of a structural steel frame. As is well known in the art, an increase in the length of a yielding core means that the strain rate on the yielding core will be less, resulting in a fatigue life which is longer than the fatigue life of a similar brace secured at a similar location using conventional, rigid connection apparatus.  
         [0015]     Additionally, a connection apparatus according to the present invention may include a collar with one or more members that extend over a junction between the brace-side member and the end of a seismic brace on which the connection apparatus is used. By way of example only, a first end of each member of a collar may be secured to one or both of a portion of the brace-side member (e.g., the knife plates or intermediate member) or to the core of a seismic brace with which the connection apparatus is used, while a second end of each collar member may be positioned adjacent to an external shell, or shell, sleeve, or tube exterior, or other exterior surface of the seismic brace. The collar may be permitted to slide longitudinally relative to the external sleeve as the yielding core is compressed and elongated. It is currently preferred that at least a portion of the collar member extend over and substantially parallel to an end portion of the external shell or other exterior surface of the seismic brace.  
         [0016]     Such a connection apparatus may be used with a variety of types of compression and tension-type seismic braces, including those with single, somewhat planar yielding cores, as well as those with multiple cores. The collar of the connection apparatus may also be used with other types of connection apparatus, including known, rigid connection apparatus for seismic braces. The collar is particularly useful with seismic braces that include axial-load-bearing cores that are surrounded by buckling-limiting material encased by external sleeves.  
         [0017]     In another embodiment, the frame-side member of a connection apparatus according to the present invention may include a pair of gusset plates, while the brace-side member of such a connection apparatus comprises an exposed end of a core of a seismic brace or an extension therefrom which is rigidly secured thereto. The gusset plates of the frame-side member are configured to be secured to a steel structural frame in spaced-apart relation to one another and oriented substantially parallel to each other, with an aperture formed through each gusset plate being in substantial alignment with an aperture of the other gusset plate. The brace-side member is configured to be positioned between the gusset plates such that an aperture thereof substantially aligns with the substantially aligned apertures of the gusset plates. Upon arranging and assembling the frame-side and brace-side members in this manner, a coupling member, such as an elongate member with a substantially cylindrical center section (e.g., a pin, bolt, etc.), may be introduced into the substantially aligned apertures.  
         [0018]     Of course, other arrangements and configurations of apparatus for connecting seismic braces to steel structural frames are also within the scope of the present invention. For example, another embodiment of connection apparatus that incorporates teachings of the present invention may comprise a ball-and-socket type connection apparatus. The first member, or frame-side member, of such a connection apparatus, which is securable to a steel structural frame, may comprise a socket. The socket may, for example, be in the form of an aperture with a concave edge. The coupling member of such a connection apparatus may comprise a ball, which may be spherical in shape, an oblong spheroid, disc-shaped, or otherwise configured to fit within the socket of the frame-side member and rotate somewhat relative to the frame-side member. The coupling member may also include one or more pins protruding from opposite sides thereof. The second member, or brace-side member, of a ball-and-socket type connection apparatus includes a pair of substantially planar members which are spaced apart a sufficient distance that the ball of the coupling member may be positioned therebetween. An aperture formed through each substantially planar member is configured to receive a portion of a pin protruding from the ball and, thus, facilitates hinged movement of the brace-side member and of a seismic brace to which the brace-side member is secured relative to one or both of the ball and the frame-side member of the connection apparatus.  
         [0019]     In use, the frame-side member of a connection apparatus of the present invention is secured to a steel structural frame, such as in a corner formed between conjoined horizontal beams and vertical steel columns. Continuing with the above examples, this may be effected by welding or otherwise securing one or more gusset plates into such a corner. The brace-side member of the connection apparatus, which, preferably, has already been secured to or formed at the end of a core of a seismic brace, is then positioned appropriately relative to the frame-side member, such that apertures of the frame-side and brace-side members are substantially mutually aligned. A coupling member is then introduced into the aligned apertures so as to be positioned within each of the substantially aligned apertures of the frame-side and brace-side members. The coupling member is then secured in this position to prevent inadvertent removal thereof from the apertures. The opposite end of the seismic brace may then be similarly secured to another (higher or lower) horizontally extending steel beam. Alternatively, another type of connection, including a rigid, conventional connection, may be used to secure the other end of the seismic brace to the other horizontally extending beam. As a single pin is secured in position rather than several bolts, as required by conventional, rigid connection apparatus, erection of a seismic brace that includes a connection apparatus according to the present invention is simpler and faster than erection with conventional, rigid connection apparatus.  
         [0020]     When a building that includes a frame with one or more seismic braces connected thereto by way of a connection apparatus of the present invention is subjected to a load, such as that generated by shock waves (e.g., seismic shock waves, high winds, etc.), the connection apparatus and the adjacent end of the seismic brace are substantially isolated from external moments that result from movement of the seismic brace out of the plane of the bay of a steel structural frame in which the seismic brace is located. The collar resists in-plane and out-of-plane moments on the exposed portions of the core of the seismic brace, as well as of the remainder of the connection apparatus, thereby permitting only substantially axial loads to be applied to the core, providing support to the core and the remainder of the connection apparatus, and preventing weak axis buckling of the core. In addition, the connection apparatus reduces the moments and shears that result from the application of gravity and earthquake loads to a steel structural frame by providing a larger moment of inertia at the ends of the core of a seismic brace. As a result, the connection element substantially limits the forces that are applied to the seismic brace to those which may be properly absorbed thereby.  
         [0021]     As a further result of providing a nonrigid connection, the likelihood of a connection apparatus according to the present invention being damaged when subjected to gravity and earthquake loads is much lower than the likelihood of a conventional rigid connection being damaged. Thus, following failure due to absorption of excessive earthquake loads, a seismic brace which is at least partially secured to a steel structural frame by way of one or more of the inventive connection apparatus may still have some load-bearing capabilities and, thus, provide some structural support to a steel structural frame, whereas seismic braces that are secured in place by weakened conventional rigid connections would be less likely to provide such support.  
         [0022]     Other features and advantages of the present invention will become apparent to those of ordinary skill in the art through a consideration of the ensuing description, the accompanying drawings, and the appended claims. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0023]     In the drawings, which illustrate various features of exemplary embodiments of the present invention:  
         [0024]      FIG. 1  is a schematic representation of a bay of a steel structural frame with a pair of seismic braces, which are positioned within the bay in a conventional fashion, coupled to the steel structural frame;  
         [0025]      FIG. 2  depicts an example of a conventional rigid connection between a steel structural frame and an exposed end of a yielding core of a seismic brace;  
         [0026]      FIG. 2A  is a cross-section taken along line  2 A- 2 A of  FIG. 2 ;  
         [0027]      FIG. 2B  is a cross-section taken along line  2 B- 2 B of  FIG. 2 ;  
         [0028]      FIG. 3  is side view of an example of a seismic brace with which a nonrigid connection apparatus that incorporates teachings of the present invention may be used, as well as an exemplary embodiment of nonrigid connection apparatus;  
         [0029]      FIG. 4  is a cross-section taken through line  414  of  FIG. 3 ;  
         [0030]      FIG. 5  is a side view of the embodiment of nonrigid connection apparatus shown in  FIG. 3 ;  
         [0031]      FIG. 6  is a perspective view of a brace-side member of the nonrigid connection apparatus of  FIGS. 3 and 5 ;  
         [0032]      FIG. 7  is a perspective view of a frame-side member of the nonrigid connection apparatus of  FIGS. 3 and 5 ;  
         [0033]      FIG. 8  is a perspective assembly view of another embodiment of nonrigid connection apparatus according to the present invention;  
         [0034]      FIG. 9  is a perspective view of the nonrigid connection apparatus shown in  FIG. 8 ;  
         [0035]      FIG. 10  is a top view of the nonrigid connection apparatus of  FIGS. 8 and 9 ;  
         [0036]      FIG. 11   is  a cross-sectional representation of a brace-side member of yet another embodiment of nonrigid connection apparatus according to the present invention;  
         [0037]      FIG. 12  is a perspective assembly view of a ball-and-socket embodiment of nonrigid connection apparatus incorporating teachings of the present invention, which includes a coupling element comprising a ball;  
         [0038]      FIG. 13  is a cross-section taken along line  13 - 13  of  FIG. 12 ;  
         [0039]      FIG. 13A  a cross-sectional representation of a variation of the coupling element of the nonrigid connection apparatus shown in  FIGS. 12 and 13 ;  
         [0040]      FIG. 13B  is a cross-sectional representation of another variation of the coupling element of the nonrigid connection apparatus shown in  FIGS. 12 and 13 , which comprises a disc rather than a ball;  
         [0041]      FIG. 14  is a side view of the nonrigid connection apparatus of  FIGS. 12 and 13 ;  
         [0042]      FIG. 15  is a top view of the nonrigid connection apparatus of  FIGS. 12 through 14 ;  
         [0043]      FIG. 16  is a side view of an example of use of the brace-side member of the nonrigid connection apparatus depicted in  FIGS. 3-7  with a plurality of seismic braces; and  
         [0044]      FIGS. 17-19  are cross-sectional representations of various examples of multiple-brace arrangements that may be used as shown in  FIG. 16 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0045]     With reference to  FIGS. 3 and 4 , a seismic brace  100  that incorporates teachings of the present invention is depicted. In the illustrated example, seismic brace  100  is a single-core, compression and tension member which includes an elongate, substantially hollow exterior shell  102 , a buckling-limiting member, which is also referred to herein as “containment  106 ,” within exterior shell  102 , and an elongate yielding core  110  positioned substantially centrally within and extending completely along the length of containment  106 . The depicted yielding core  110  has a rectangular, somewhat planar cross-section, taken transverse to the length thereof, and includes ends  113  and  114  which extend beyond corresponding ends  103 ,  104  of exterior shell  102 . Yielding core  110  is positioned within an aperture  108  that extends substantially through containment  106  and includes at least one surface  111  which is spaced apart from an interior surface  107  of containment  106  by way of a readily compressible medium  109 , such as a polymer, air, or the like. Although  FIG. 3  depicts a particular embodiment of seismic brace  100 , which comprises a single-core member that may be subjected to compressive and tensile loads, other types of seismic braces, including all-steel seismic braces which lack a buckling-limiting member, may also be used in accordance with teachings of the present invention.  
         [0046]     With continued reference to  FIG. 3 , a brace-side member  130  of an exemplary embodiment of nonrigid connection apparatus  120  according to the present invention is located at at least one end  113 ,  114  of yielding core  110 . Brace-side member  130  is also referred to herein as a second member, or simply as a member, of nonrigid connection apparatus  120  and as a nonrigid connection element.  
         [0047]     As shown in  FIG. 5 , brace-side member  130  includes an intermediate member, in this case an end plate  132 , which is secured to end  113 ,  114  of yielding core  110 , such as by welds  134 . Brace-side member  130  also includes two knife plates  136  and  138  secured to and extending from end plate  132  in mutually parallel relation. Welds  140  or other known fixing means may secure knife plates  136  and  138  to end plate  132 . As shown, knife plates  136  and  138  may extend in substantially the same direction as seismic brace  100  ( FIGS. 3 and 4 ) and may be oriented substantially perpendicular to end plate  132 .  
         [0048]     Turning to  FIG. 6 , each knife plate  136 ,  138  of brace-side member  130  of nonrigid connection apparatus  120  ( FIGS. 3 through 5 ) includes an aperture  137 ,  139 , respectively formed therethrough. Apertures  137  and  139 , which are both configured to receive a central portion  162  ( FIG. 5 ) of a coupling member  160  ( FIG. 5 ) of nonrigid connection apparatus  120 , are in substantial alignment with one another.  
         [0049]     With briefly returned reference to  FIG. 3 , knife plates  136  and  138  of brace-side member  130  are spaced a sufficient distance apart from one another that a corresponding feature (e.g., gusset plate  152  of  FIG. 7 ) of a frame-side member  150  of nonrigid connection apparatus  120  may be positioned therebetween.  
         [0050]     As depicted in  FIG. 7 , an exemplary embodiment of a frame-side member  150  of nonrigid connection apparatus  120  ( FIGS. 3 through 5 ) is shown. Frame-side member  150  is also referred to herein as a first member, or simply as a member, of connection apparatus  120  or as a nonrigid connection element. The illustrated frame-side member  150  comprises a single, substantially planar gusset plate  152 , which is configured to be fixed in place relative to a member of a steel structural frame  30 , such as one or more of a conjoined beam  34  and/or column  36  thereof. While gusset plate  152  is shown in the illustrated example as being secured in a corner formed at a junction between a horizontally oriented beam  34  and a vertically oriented column  36 , gusset plate  152  maybe secured to any suitable surface (i.e., within a bay  32  of steel structural frame  30 ) of a single beam  34  or column  36 . Also, while  FIG. 7  depicts gusset plate  152  as being held in place by welds  153 , other fixing means for securing gusset plate  152  into position (e.g., rivets, bolts, etc., for securing gusset plate  152  to a lip (not shown) protruding from beam  34  and column  36 ) are also within the scope of the present invention.  
         [0051]     The dimensions of gusset plate  152  and the type of fixing means used to secure the same to a steel structural frame  30 , including the height, length, and thickness thereof, are configured to withstand predetermined amounts of load, moment, and other stresses. Accordingly, the dimensions of gusset plate  152  depend at least partially upon the material (e.g., the type of steel) from which gusset plate  152  is fabricated, as well as the size of seismic brace  100  ( FIG. 3 ) to be used therewith, the location of a steel structural frame  30  at which seismic brace  100  is to be used, and other factors, as known in the art.  
         [0052]     Gusset plate  152  of frame-side member  150  of connection apparatus  120  includes an aperture  154  therethrough. Aperture  154  may have substantially the same internal crosswise dimensions (e.g., radius) as apertures  137  and  139  ( FIG. 6 ) of substantially planar knife plates  136  and  138 , respectively, of brace-side member  130  of nonrigid connection apparatus  120 . Upon positioning substantially planar knife plates  136  and  138  on opposite sides of a gusset plate  152  which has been fixed into position relative to a steel structural frame  30  into an appropriate assembled relationship, apertures  137  and  139  of substantially planar knife plates  136  and  138 , respectively, are in substantial alignment with aperture  154  of gusset plate  152 .  
         [0053]     Referring again to  FIG. 5 , apertures  137 ,  139 , and  154  are sized and configured to receive a central portion  162  of a coupling member  160  of nonrigid connection apparatus  120 . When positioned within apertures  137 ,  139 , and  154  of assembled brace-side and frame-side members  130  and  150 , respectively, coupling member  160  nonrigidly couples brace-side member  130  and frame-side member  150  in the assembled relationship thereof. In this case, the nonrigid coupling is a hinged connection, at which movement may occur in substantially a single plane and at a substantially single pivot point.  
         [0054]     Coupling member  160  is held in place within apertures  137 ,  139 , and  154  by position-retaining elements  164 , such as enlarged heads or nuts at the ends thereof, bent regions at the ends thereof, securing elements that extend through apertures near the ends thereof, transversely to the length of the coupling member  160  (e.g., like cotter pins), or the like. Of course, combinations of different types of position-retaining elements  164  may be used to secure a coupling member  160  into place relative to frame-side member  150  and brace-side member  130  of nonrigid connection apparatus  120 .  
         [0055]     With continued reference to  FIG. 5 , a support collar  170  is also depicted. Support collar  170  includes a distal end  175 , which is configured to be positioned at or near brace-side member  130  of nonrigid connection apparatus  120 , and a proximal end  176 , which is configured to extend at least partially over an end  103 ,  104  of exterior shell  102 . Proximal end  176  of support collar  170  may be permitted to slide relative to a length of exterior shell  102 . As proximal end  176  of support collar  170  is to be positioned over an end  103 ,  104  of exterior shell  102 , at least the portion of a hollow center  173  thereof which is to receive an end  103 ,  104  of exterior shell  102  has internal dimensions which are roughly the same as or slightly greater than the corresponding external dimensions of that end  103 ,  104 . When properly positioned over an end  113 ,  114  of a yielding core  110  of a seismic brace  100  ( FIGS. 3 and 4 ), support collar  170  substantially isolates yielding core  110  from external shear and moment, instead absorbing some of the external shear and moment and transmitting external shear and moment to exterior shell  102 . Thus, such positioning of seismic brace  100  isolates ends  113 ,  114  against loads that are placed transversely on seismic brace  100  with respect to the axis or length thereof.  
         [0056]     The exemplary support collar  170  which is shown in  FIG. 5  includes first and second halves  171  and  172 , respectively. When assembled, first half  171  and second half  172  form an elongate structure with a substantially rectangular cross-section taken transverse to the length of the assembled support collar  170  and a hollow center  173 . First half  171  and second half  172  may be secured to one another by any suitable fixing means, including, without limitation, welds, rivets, nuts and bolts, and the like. As an alternative to the depicted embodiment of support collar  170 , support collar  170  may comprise a single piece. Other variations of support collars that incorporate teachings of the present invention and, thus, that are within the scope of the present invention include support collars with more than two pieces. Also, support collars that include a plurality of elements which are not secured directly to one another but, rather, which are secured to a seismic brace  100  ( FIGS. 3 and 4 ) and a brace-side member  130  of a nonrigid connection apparatus  120  are within the scope of the present invention.  
         [0057]      FIGS. 8 through 10  depict another exemplary embodiment of nonrigid connection apparatus  120 ′ according to the present invention.  
         [0058]     As shown in  FIGS. 8 through 10 , a brace-side member  130 ′ of nonrigid connection apparatus  120 ′ includes a single, knife plate  136 ′ with an aperture  137 ′ formed therein. Knife plate  136 ′ may be secured, by appropriate fixing means, to an intermediate member, such as an end plate  132 ′, that has been secured to an end  113 ,  114  of a yielding core  110  of a seismic brace  100 . Alternatively, knife plate  136 ′ may be secured directly to end  113 ,  114 .  
         [0059]     Frame-side member  150 ′ of nonrigid connection apparatus  120 ′ includes two substantially planar gusset plates  152 ′. Each gusset plate  152 ′ includes an aperture  154 ′ formed therethrough. Gusset plates  152 ′ of frame-side member  150 ′ are spaced apart from one another and oriented in substantially parallel relation to one another with apertures  154 ′ thereof in substantial axial alignment. The spacing between gusset plates  152 ′ is sufficient to permit the insertion of knife plate  136 ′ therebetween.  
         [0060]     When knife plate  136 ′ is positioned between gusset plates  152 ′ in an appropriate assembled relationship thereof, aperture  137 ′ of knife plate  136 ′ and apertures  154 ′ of gusset plates  152 ′ are in substantial axial alignment with one another. Accordingly, a coupling member  160  of nonrigid connection apparatus  120 ′ may be introduced into apertures  137 ′ and  154 ′ and secured in place relative to both brace-side member  130 ′ and frame-side member  150 ′ of nonrigid connection apparatus  120 ′, as described previously herein with reference to  FIG. 5 .  
         [0061]      FIGS. 8 and 9  depict another exemplary support collar  170 ′ that may be used with nonrigid connection apparatus  120 ′ or any other embodiment of nonrigid connection apparatus that incorporates teachings of the present invention. Support collar  170 ′ includes four elongate members  172 ′, with cross-sections taken transverse to the length thereof having an “L” shape. A first end  173 ′ of each elongate member  172 ′ is secured (e.g., by welds or other suitable fixing means) to a corner  133 ′ of end plate  132 ′, while an opposite, second end  174 ′ of each elongate member  172 ′ is secured to an end  103  of exterior shell  102 . As there are four elongate members  172 ′ in the depicted example, one elongate member  172 ′ extends between each corner  133 ′ of end plate  132 ′ and a corresponding end  103  of exterior shell  102 .  
         [0062]     In another, similar embodiment of nonrigid connection apparatus  120 ″, shown in  FIG. 11 , brace-side member  130 ″ comprises an end  113 ″,  114 ″ of yielding core  110 ″ of seismic brace  100 ″. An aperture  137 ″ formed through end  113 ″,  114 ″ is configured to receive a central portion  162  ( FIG. 5 ) of a coupling member  160  of nonrigid connection apparatus  120 ″.  
         [0063]     A frame-side member  150 ′ of nonrigid connection apparatus  120 ″ is the same as that shown and described previously herein with reference to  FIGS. 8 through 10  and, thus, includes a pair of gusset plates  152 ′. Gusset plates  152 ′ of frame-side member  150 ′ are arranged substantially parallel to one another with apertures  154 ′ thereof in substantial axial alignment and are spaced apart a sufficient distance that end  113 ″,  114 ″ of yielding core  110 ″ may be positioned therebetween. Upon positioning end  113 ″,  114 ″ between gusset plates  152 ′ and substantially axially aligning aperture  137 ″ with apertures  154 ′, coupling member  160  may be placed within the substantially aligned apertures  154 ′ and  137 ″ so as to nonrigidly connect end  113 ″,  114 ″ to frame-side member  150 ′, as described previously herein with reference to  FIGS. 5 and 8  through  10 . Coupling member  160  may then be secured in place, as described previously herein with reference to  FIGS. 5 and 8  through  10 .  
         [0064]     A support collar  170 ″ which is configured to be used with brace-side member  130 ″ includes an end plate  177 ″ with a slot  178 ″ formed therethrough to receive end  113 ″,  114 ″ of yielding core  110 ″. End plate  177 ″ is positioned at an intermediate location along end  113 ″,  114 ″ of yielding core  110 ″.  
         [0065]     In addition to being useful with nonrigid connection apparatus of the types described herein, support collars (e.g., support collar  170 ,  170 ′,  170 ″) that incorporate teachings of the present invention may also be used with other types of connection apparatus, including other nonrigid connection apparatus, as well as the nonrigid connection apparatus (e.g., gusset plate bolted to brace ends with cross-sections taken along the lengths thereof that are cruciform in shape).  
         [0066]     Another exemplary embodiment of nonrigid connection apparatus  220  that incorporates teachings of the present invention is depicted in  FIGS. 12 through 15 .  
         [0067]     As shown in  FIG. 12 , nonrigid connection apparatus  220  includes a brace-side member  230 , which is configured to be secured to a seismic brace  100  ( FIGS. 3 and 4 ), and a frame-side member  250 , which is configured to be secured to a steel structural frame. Nonrigid connection apparatus  220  also includes a coupling member  260 , which nonrigidly secures brace-side member  230  to frame-side member  250  and, thus, a seismic brace  100  to a steel structural frame  30 . As depicted, nonrigid connection apparatus  220  comprises a ball-and-socket type joint, with frame-side member  250  comprising the socket, coupling member  260  comprising the ball, and brace-side member  230  being pivotally secured to the ball of coupling member  260 .  
         [0068]     As shown in  FIGS. 12 and 13 , frame-side member  250  may comprise a pair of substantially planar gusset plates  252  with large apertures  254  formed therein. Each aperture  254  includes a concave edge  256 , the curvature of which is configured to complement at least a portion of an exterior surface of coupling member  260  so as to retain coupling member  260  within aperture  254 . Of course, the thickness of gusset plate  252 , the sizes of apertures  254 , and the curvatures of concave edges  256  may be configured to retain coupling member  260  under seismic and gravitational loads and, thus, when tensile and compressive loads are being applied to seismic brace  100  ( FIGS. 3 and 4 ).  
         [0069]     Gusset plate  252  may be secured to one or more of a beam  34  and a column  36  of a steel structural frame  30  as known in the art, such as by welds, nuts and bolts, rivets, or the like.  
         [0070]      FIGS. 12 and 13  illustrate coupling member  260 , which includes a ball  262 . As shown, ball  262  is spheroid in shape, comprising a sphere, although oblong spheroids are also within the scope of the present invention, as are spheres and spheroid structures that have substantially opposite planar surfaces. Ball  262  is configured to be introduced into aperture  254  of frame-side member  250  in such a way that an engaging region  263  of ball  262  is engaged by concave edges  256  of apertures  254 , between gusset plates  252  and, thus, retained at least partially within apertures  254 .  
         [0071]     The exemplary coupling member  260  depicted in  FIGS. 12 and 13  also includes an aperture  264  extending axially through ball  262 , as well as an elongate pin  266  positioned within aperture  264  so as to extend completely through ball  262  and to protrude from opposite sides thereof. Alternatively, as shown with respect to coupling member  260 ′ of nonrigid connection apparatus  220 ′ in  FIG. 13A , two pins  266 ′ may be secured to opposite sides of a ball  262 ′ (e.g., by threadingly engaging apertures  268 ′ in opposite sides of ball  262 ′, as shown, by welds, etc.).  
         [0072]     Of course, variations of coupling members are also within the scope of the present invention, including, without limitation, coupling member  260 ″ depicted in  FIG. 13B , which includes a disc-shaped element  262 ″ with a coupling portion comprising a rounded ridge  263 ″ extending around at least a portion of the outer circumference thereof. Rounded ridge  263 ″ is configured to be engaged by a concave edge  256 ″ of an aperture  254 ″ of frame-side member  250 ″ of nonrigid connection apparatus  220 ″ in such a way that disc-shaped element  262 ″ may at least partially rotate about its axis A within aperture  254 ″, as well as move laterally, into and out of a plane P in which gusset plate  252 ″ is located, as shown by arrows  269 .  
         [0073]     Like coupling members  260  and  260 ′, coupling member  260 ″ may include one or more pins  266 ″ protruding from opposite sides of disc-shaped element  262 ″. As shown, each pin  266 ″ may be positioned so as to extend substantially along axis A of disc-shaped element  262 ″.  
         [0074]     With returned reference to  FIG. 12 , as well as reference to  FIGS. 14 and 15 , brace-side member  230  of nonrigid connection apparatus  220  may be configured substantially as brace-side member  130  described above with reference to  FIGS. 3 through 6 . Thus, brace-side member  230  may include an end plate  232 , which is secured to end  113 ,  114  of yielding core  110  ( FIGS. 3 and 4 ), to which two knife plates  236  and  238  are secured. Knife plates  236  and  238  extend from end plate  232  in mutually parallel relation. As shown, knife plates  236  and  238  may extend in substantially the same direction as seismic brace  100  ( FIGS. 3 and 4 ) and may be oriented substantially perpendicular to end plate  232 . Knife plates  236  and  238  are spaced a sufficient distance apart from one another that frame-side member  250  and ball  262 ,  262 ′ or disc-shaped element  262 ″ of a respective coupling member  260 ,  260 ′,  260 ″ may be positioned therebetween.  
         [0075]     Each knife plate  236 ,  238  of brace-side member  230  of nonrigid connection apparatus  220  includes an aperture  237 ,  239  formed therethrough. Apertures  237  and  239  are both configured to receive a portion of a pin  266 ,  266 ′,  266 ″ ( FIGS. 13, 13A , and  13 B, respectively) of a complementary coupling member  260 ,  260 ′,  260 ″ in such a way that brace-side member  230  and, thus, a seismic brace  100  to which brace-side member  230  is secured, may pivot about an axis A defined by pins  266 ,  266 ′,  266 ″.  
         [0076]     As is apparent from the foregoing description, nonrigid connection apparatus  220 ,  220 ′,  220 ″ allow a seismic brace  100  to pivot relative to frame-side member  250  in more than one plane. Accordingly, nonrigid connection apparatus  220 ,  220 ′ and  220 ″ substantially isolate seismic brace  100  from shear, moment, and loads that are nonaxial to seismic brace  100 .  
         [0077]     Turning now to  FIGS. 16-19 , use of a brace-side member  130  of a nonrigid connection apparatus according to the present invention with a plurality of seismic braces  100  is depicted. In  FIG. 16 , end plate  132  of brace-side member  130  is depicted as having yielding cores  110  of at least two seismic braces  100  secured thereto. Support collar  170  surrounds the adjacent end  103 ,  104  of exterior shell  102  of each seismic brace  100 .  FIG. 17  depicts a multi-brace embodiment that includes two seismic braces  100  with yielding cores  110  that are in a mutually parallel arrangement.  FIG. 18  shows another multi-brace embodiment that includes three seismic braces  100  and  100 ′ that are arranged in a linear fashion.  FIG. 19  illustrates yet another multi-brace embodiment that includes four seismic braces  100  in a two-by-two arrangement.  
         [0078]     Multi-brace embodiments of the present invention are not limited to the depicted nonrigid connection apparatus  120 , but may also be used with other embodiments of nonrigid connection apparatus that incorporate teachings of the present invention. Moreover, while each of the seismic braces  100 ,  100 ′ shown in  FIGS. 16-19  includes an exterior shell  102  within which a yielding core  110  and a surrounding containment  106  are disposed, other types of seismic braces may also be secured to brace-side member  130  without departing from the scope of the present invention. In addition, it is within the scope of the present invention to secure two or more different types of seismic braces to the same brace-side member (e.g., brace-side member  130 ) of a nonrigid connection apparatus (e.g., nonrigid connection apparatus  120  ( FIG. 5 )) incorporating teachings of the present invention.  
         [0079]     Although the foregoing description contains many specifics, these should not be construed as limiting the scope of the present invention, but merely as providing illustrations of some of the presently preferred embodiments. Similarly, other embodiments of the invention may be devised which do not depart from the spirit or scope of the present invention. Moreover, features from different embodiments of the invention may be employed in combination. The scope of the invention is, therefore, indicated and limited only by the appended claims and their legal equivalents, rather than by the foregoing description. All additions, deletions, and modifications to the invention, as disclosed herein, which fall within the meaning and scope of the claims are to be embraced thereby.