Patent Publication Number: US-6658804-B2

Title: Self-bearing flexible curtain wall system

Description:
TECHNICAL FIELD 
     The present invention relates to curtain walls, and more particularly to a self-bearing flexible curtain wall system for cladding a structure. 
     BACKGROUND OF INVENTION 
     In the construction of enclosed buildings, it is generally most efficient to construct the columns, floors, roof, and internal supporting walls initially, and, thereafter to enclose the structure by constructing the exterior walls. A curtain wall system is an exterior wall system (i.e., a cladding) installed outboard of the building perimeter frame to provide protections against the exterior weather conditions. In addition to a traditional utilitarian function, curtain wall systems are further called upon to satiate aesthetic functionality. 
     Curtain wall systems are generally of two varieties, namely “stick” or “unitized.” The stick curtain wall system is one in which the primary structural framing components are erected individually in the field, with vertical mullions typically attached to the floor slabs, with horizontals subsequently attached to the vertical mullions. Thereafter, the vision glass and spandrel materials are field installed into the assembled grid work. 
     The unitized curtain wall system is one in which the framing members are preassembled and erected in modules of a manageable size and weight. The wall modules are of a height generally equal to the building&#39;s storey height. The assembled and pre-glazed modules are supported by connectors upon the outer area of the building floor. Modules are stacked upon each other in parallel rows, and adjacent modules are often connected together by means of male-female interlocking. Vertical and horizontal mating joints can either be dry-sealed with gaskets, or wet-sealed with field supplied sealants. Needless to say, quite a variety of techniques and hardware are available to generally fasten the wall modules to the structural elements of a building, in addition to the wide variation in constructing the modules in the first instance. 
     Although modules may be constructed as load bearing exterior walls, higher buildings require that each building floor support a row of modules of a height equal to the building&#39;s storey height. The exterior wall system is normally supported on spaced apart vertical mullions. The vertical mullions are structurally connected to the building perimeter frame to provide two structural functions, namely to support the dead weight of the exterior wall system, and to resist reaction forces transmitted from the exterior wall system due to lateral (wind and/or earthquake) loads. Commonly used anchorage placements for joining the mullions to the building are located along the edges of the roof and floor slabs. In addition to lateral load resisting requirements, the functional requirement of the curtain wall includes water tight performance and maintaining a certain degree of air tightness for the consideration of thermal efficiency. An important consideration towards this end, is the effect of the relative deflection along the edges of the slabs between floors due to the variable live loads and the effect of building frame interstory movements due to lateral forces. 
     As architects continue to be called upon to design more aesthetically pleasing structures, and advances are made in cladding technology/material science, structural soundness, typically manifest in the form of economic viability/feasibility, remains the touch stone of cladding innovation. For example, structures such as the Philadelphia Regional Performing Arts Center, presently under construction, and the Shanghai Communication Center evidence the advances being made in cladding systems, more particularly in the area of glazed elements supported by a system of prestressed cables. Be this as it may, there remains a need for a self-bearing flexible curtain wall system, more particularly, a system wherein a matrix of kinematically integrated cladding panels includes vertically adjacent panels which are load bearing (i.e., dead load is transferred down along the vertical linkages between vertically adjacent panels). 
     SUMMARY OF THE INVENTION 
     A self-bearing flexible curtain wall system is provided, the system including a matrix of unitized kinematically integrated cladding panels flexibly joined to a structural member as for example, a prestressed, substantially vertical, cable or cable like element (e.g., rod, bar, etc.). Adjacent cladding panels of the matrix of unitized cladding panels are responsively linked horizontally and vertically for horizontal and vertical rotation. Horizontally adjacent cladding panels of the matrix of unitized cladding panels are responsively joined to a structural member via an anchor fixture, which allows the cladding panels to remain in a substantially static condition when the cables move along wall elevation due to main structure movement and/or distortion. More specific features and advantages will become apparent with reference to the DETAILED DESCRIPTION OF THE INVENTION, appended claims, and the accompanying drawing figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial elevation view of the self-bearing flexible curtain wall system of the subject invention; 
     FIG. 2 is a cross-section view of the cladding of FIG. 1 taken about line  2 — 2 ; 
     FIG. 3 is a perspective overhead view of elements of the self-bearing flexible curtain wall system of the subject invention; 
     FIG. 4 is an enlarged view of area  4  of FIG. 1; 
     FIG. 5 is a cross-section view of components of the self-bearing curtain wall system of the subject invention taken about line  5 — 5  of FIG. 4, anchoring normal to a structural element; 
     FIG. 6 is a view as FIG. 5, particularly illustrating horizontal rotation of vertically adjacent cladding panels, the exterior sealing assembly in expansion, anchoring negatively deviating from normal; 
     FIG. 7 is a view as FIG. 5, particularly illustrating horizontal rotation of vertically adjacent cladding panels, the exterior sealing assembly in compression, anchoring positively deviating from normal; 
     FIG. 8 is an enlarged view of area  8  of FIG. 7, particularly showing elements of the vertical linkage assembly; 
     FIG. 9 is a cross-section view of components of the self-bearing flexible curtain wall system of the subject invention taken about line  9 — 9  of FIG. 4, particularly showing vertical rotation of horizontally adjacent cladding panels, the exterior sealing assembly in compression with spread exhibited; 
     FIG. 10 is a view as FIG. 9, particularly showing vertical rotation of horizontally adjacent cladding panels, the exterior sealing assembly in expansion with approach exhibited; 
     FIG. 11 is an enlarged view of area  11  of FIG. 10, particularly showing an embodiment of the horizontal linkage assembly of the subject invention; 
     FIG. 12 is a partial view of the horizontal adjacent cladding panels of FIG. 9 particularly illustrating an alternate embodiment of the horizontal linkage assembly of the subject invention; and, 
     FIG. 13 is a partial view of the horizontal adjacent cladding panels of as FIG. 9 particularly illustrating a further alternate embodiment of the horizontal linkage assembly of the subject invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring generally to FIGS. 1 &amp; 2, a self-bearing flexible curtain wall system  20  is shown in partial plan and cross-section, respectively. The self-bearing curtain wall system  20  of the subject invention includes a matrix or array  22  of unitized cladding panels  24  (i.e., rows and columns of unitized cladding panels), adjacent cladding panels of the matrix  22  being responsively linked horizontally and vertically for horizontal and vertical rotation. Horizontally adjacent cladding panels of the matrix  22  of unitized cladding panels  24  are further united and collectively, flexibly joined to a structural member  26  (e.g., prestressed cables tensioningly extending, i.e., anchored, between the sills  28  and heads  30  of a building so supported) by an anchor fixture  32  so as to thereby responsively anchor the matrix  22  of unitized cladding panels  24 . The self-bearing flexible curtain wall system  20  of the subject invention is especially well suited for buildings with sidewalls of prestressed cables of various lengths and levels of prestress. Under normal to the wall lateral forces, the cables each deflect differently in response thereto, and the matrix  22  of unitized cladding panels  24  assumes an irregular curvature in section and in plan as will be subsequently discussed. 
     Each panel  24  of the matrix  22  of unitized cladding panels includes a periphery  34  comprising opposingly paired vertical  36  and horizontal  38  members, more particularly left  36   a  and right  36   b  paired members, and upper (i.e., head)  38   a  and lower (i.e., sill)  38   b  paired members. As previously noted, each of the panels  24  of the matrix  22  of unitized cladding panels are kinematically integrated, with groups of integrated panels (i.e., horizontal panel pairs) responsively anchored to the structural member  26  by the anchor fixture  32 . 
     Kinematic panel integration is accomplished by vertical  40  and horizontal  42  linkage assemblies. Vertical linkage assemblies  40  operatively interposed between adjacent horizontal members  38  of vertically adjacent cladding panels  24  (i.e., a head  38   a  to sill  38   b  linkage) permit rotation in section of the cladding panels. Further details of the vertical linkage assembly  40  will be presented with respect to a discussion of FIGS. 4-8. Horizontal linkage assemblies  42  operatively interposed between adjacent vertical members  36  of horizontally adjacent cladding panels  24  permit rotation in plan of the cladding panels. Further details of the horizontal linkage assembly  42  will be presented with respect to a discussion of FIGS. 9-13. 
     Referring now generally to FIGS. 3-5, the anchor fixture  32  of FIG. 1 is shown (FIG. 4) rigidly affixed at one end to the upper horizontal members (i.e., heads)  38   a  of horizontally adjacent cladding panels  24 , and slidingly affixed at the other end, at least indirectly, to the prestressed cable  26 . The anchor fixture  32  generally includes (FIG. 3) a pair of cladding brackets  44 / 44   a,  a yoke  46  pivotably supporting the bracket pair  44 / 44   a,  an anchor bracket  48  pivotably supporting the yoke  46 , and a clamp  50 , adapted to engage the prestressed cable  26 , pivotably supporting the anchor bracket  48 . 
     The anchoring or tethering of the kinematically integrated matrix  22  of unitized cladding panels  24  to or with the prestressed cables  26  are made in such a way to permit the cables  26  to move freely along the curtain wall (i.e., left/right in FIG. 1) while not involving the panels  24  of the matrix  22  in such motion. Furthermore, this union allows some angle of rotation between the cable  26  and adjacent panels in elevation, some angle of rotation between adjacent panels in plan and elevation, and some spread (i.e., joint elongation) between adjacent units in plan. 
     With particular emphasis on FIG. 3, each cladding bracket  44 / 44   a  of the pair of cladding panel brackets generally includes top (i.e., upper)  52  and bottom (i.e., lower)  54  flange portions spaced apart by a webbing  56 . The top flange portion  52  has forward  58  and rearward  60  extending segments (i.e., opposingly extending segments with respect to the webbing  56 ), the head  38   a  of the cladding panel  24  being abuttingly receivable in a crotch  62  defined by the union of the webbing  56  with the top flange  52 , more particularly the forward portion  58  thereof. The cladding brackets  44 / 44   a  are affixable to the heads  38   a  of horizontally adjacent panels  24  using conventional fasteners  64  (FIG. 5) receivable in spaced apart apertures  66  near the free ends of the forwardly extending segments  58  of the upper flanges  52  of the cladding brackets  44 / 44   a.    
     Each cladding bracket  44 / 44   a  of the pair of cladding panel brackets is vertically pivotable and horizontally translatable upon the yoke  46  so as to accommodate flexure of the horizontally adjacent panels, more particularly, relative rotation and spread therebetween. The rearwardly extending segments  60  of the upper flanges  52 , and the lower flanges  54  of the cladding brackets  44 / 44   a  include opposingly paired slots  68 . At least some portion of the yoke  46 , depending upon the spread between horizontal panels being accommodated (as will be later discussed with respect to FIGS.  10 - 15 ), is interposed between the rearwardly extending segments  60  of the upper flanges  52 , and the lower flanges  54  of the cladding brackets  44 / 44   a.  The opposingly paired slots  68  are receivable upon vertical through bolts  70  carried at opposing ends of the yoke  46 , thereby permitting rotation along the entire length of the slot for each horizontally adjacent panel about a vertical axis  72  defined by the vertical through bolts  70 . 
     The anchor bracket  48 , which pivotingly supports the yoke  46 , is generally configured so as to be “U” shaped, having a pair of opposed legs  74  extending from a webbing (i.e., closed end)  76 . A horizontal through bolt  78  or the like joins the anchor bracket  48 , at the webbing  76 , to the yoke  46 , thereby defining a horizontal axis of rotation  80  therebetween. The yoke  46  is preferably longitudinally adjustable relative to the anchor bracket  48 , the horizontal through bolt  78  being received in a longitudinal slot  82  (FIG. 9) of the yoke  46  and being secured thereto in known ways, as for instance via the cooperation of a serrated surface  84  of the yoke  46  with a serrated surface  83  of a locking element  86  carried by the horizontal through bolt  78 . 
     Vertical dimensions of the yoke  46  are somewhat smaller than the opening between flanges  52  and  54  so as to accommodate some mutual rotation in the plane wall for two horizontally adjacent panels. The clamp  50 , which pivotingly supports the anchor bracket  48  via a horizontal through bolt  88  (which defines an axis of rotation  89  for the anchor bracket  48  about the clamp  50 ), preferably includes two joined or joinable halves  90 / 90   a,  for instances male and female elements joined by mechanical means (note FIG.  10 ), to facilitate engagement of the anchor fixture  32  to the structural member  26 . Each element  90 / 90   a  of the clamp  50  includes an apertured flange  92  and a profiled portion  94 , indirectly through a frictionless sleeve receiving the prestressed cable  26 . As the yoke  46 , the opposed legs  74  of the anchor bracket  48  include longitudinal slots  82  for longitudinal adjustment of the anchor bracket  48  relative to the clamp  50  (i.e., the distance between the panels  24  of the matrix  22  of unitized cladding panels and the prestressed cable  26  can be accommodated). Surfaces  96  of the opposed legs of the anchor bracket are preferably serrated so as to cooperatively engage a serrated surface  84  of a locking element  86  in furtherance of affixation of the anchor bracket  48  to the clamp  50 . 
     With regard to hardware associated with the subject self-bearing curtain wall system, the primary structural elements of FIG. 3, such as the anchor fixture  32 , vertical linkage assembly  40 , and horizontal linkage assembly  42  are preferably aluminum extrusions. These elements may be finished consistent with aesthetic considerations and maintenance requirements. A horizontal connection assembly  42  shows horizontal pin/bolt  118  nested inside vertical member  36  by means of a tapped short box which embraces the pin. (See also FIG.  11 ). 
     With particular emphasis on FIG. 4, a group or grouping  100  of kinematically integrated panels  24 , more particularly, upper left (UL)/right (UR) and corresponding lower left (LL)/right panels (LR), is shown anchored to the structural element  26 . The anchor fixture  32  of FIG. 3 is shown in sliding engagement with the prestressed cable  26 , more particularly, an ultra high molecular weight plastic slip sleeve  102  having flared opposing ends  104  is illustrated interposed between the clamp  50  and the cable stay  106  so as to facilitate vertical translation of the anchor fixture  32  relative to the cable. The cable stay  106  preferably includes paired metallic/plastic tubing halves  108  affixed to the cable  26  via a compression clamp  110 . 
     Glazing  112  or other suitable cladding material is supported within the periphery of the panel or otherwise integral thereto, more particularly between the vertically  36  and horizontally  38  opposed panel members (e.g., mullions). Vertical and horizontal mullions (i.e., framing) of the glazed panel must be mutually attached at corresponding corners by means of a moment-resistant connection so as to resist any forces acting along the elevation. In the case of a metallic panel, adequate connection of the panel to the framing is required. Adjacent heads  38   a  and sills  38   b  are shown united by components of the vertical linkage assembly  40 , namely opposingly paired brackets  114  (see also FIGS.  3  and  5 ). The brackets  114  are preferably integral to the opposing vertical members  36  of the adjacent panels  24  as will be later illustrated and discussed. Weather protection seal  116  (i.e., the exterior component of the exterior sealing system) are interposed between adjacent panels. 
     Referring now generally to FIGS. 5-8, the interrelatedness of vertically adjacent kinematically linked panels, more specifically the elements of the self-bearing curtain wall system of the subject invention, is evidenced. To a lesser extent, elements of the horizontal linkage assembly  42  are shown, more particularly the horizontal pin  118  thereof is shown (FIG. 5) resting in a key way  120  comprising a pin entry aperture  122  and a pin slot  124  extending downwardly therefrom. The key way  120  is preferably integral to the opposingly paired vertical members or mullions  36  of the horizontally paired panels as will be subsequently detailed with respect to a discussion of FIGS. 9-13, and the notion of spread. 
     The nature of the anchoring or tethering of the kinematically integrated matrix of unitized cladding panels to or with the prestressed cables, more particularly the nature of the vertical interrelatedness of the anchor fixture elements  32  (i.e., the cladding panel brackets  44 / 44   a,  yoke  46 , anchor bracket  48 , and clamp  50 ) is likewise appreciated upon review of FIGS. 5-7. FIG. 5 illustrates a portion of the matrix of unitized cladding panels in a condition or configuration substantially normal to the structural element; FIG. 6 illustrates horizontal rotation (α˜4°) of vertically adjacent cladding panels, a joint seal in expansion and anchoring negatively deviating from normal (i.e., above the horizon); and, FIG. 7 illustrates horizontal rotation (α˜4°) of vertically adjacent cladding panels, the joint seal in compression and anchoring positively deviating from normal (i.e., below the horizon). As previously noted with respect to FIG. 3, the anchor fixture  32  includes a cladding panel bracket pivot  72 , a yoke pivot  80 , and an anchor bracket pivot  89 , rotation about the anchor bracket pivot  89  being especially illustrated in the subject views. 
     The vertical linkage assembly  40  generally includes opposingly paired brackets  114  and a vertical pin  126  receivable through a webbing  128  of each of same. The webbing  128  of each of the opposingly paired brackets  114  includes a convex exterior surface  130 , the horseshoe style brackets  114  arranged to be in abutting engagement, convex surfaces  130  in opposition, in the vertical linkage assembly  40  (FIG.  8 ). The head horseshoe  114  is shown having a portion of the pin  126  secured thereto (i.e., threads  132  adjacent a bolt head  134  are threadingly received within the webbing  128  of the horseshoe  114  of the upper horizontal member  38   a  of the lower panel of the vertically aligned panel pair so as to be integral therewith). An aperture  136  of the webbing  128  of the sill horseshoe  114  includes an enlarged portion  138 , distal of the convex surface  130  thereof, so as to accommodate rotation of the upper panel relative to the lower panel (i.e., rocking of the sill bracket upon the head bracket). The horseshoe-like brackets  114  of the vertical linkage assemblies  40  are generally carried by the adjacently paired vertical members  36   a  of the periphery  34  of each panel  24  of the matrix  22  of unitized cladding panels, more preferably, the horseshoes  114  are integral to the vertical mullions  36  of the glazed panels  24  (see FIGS.  3  and  5 ). 
     The vertical linkage assemblies  40 , and joints formed thereby, transfer dead load all the way along the verticals, with the vertical pin  126  transferring lateral load between vertically adjacent panels and allowing the required angle of rotation in section to accommodate cable curvature (see FIGS.  6  &amp;  7 ). In this way, and by such interrelatedness, the matrix  22  of unitized cladding panels  24  is self supported, more particularly, each column of panels  24  within the matrix  22  is self-bearing. 
     Referring now to FIGS. 9-13, the nature of horizontally adjacent panel integration is shown, namely, the combination of the previously described anchor fixture  32  (i.e., the cladding panel bracket  44 / 44   a  interface with the heads  33   a  of horizontally adjacent panels) and the horizontal linkage assemblies  42 . The nature of the anchoring or tethering of the kinematically integrated matrix of unitized cladding panels to or with the prestressed cables, more particularly the nature of the horizontal interrelatedness of the anchor fixture  32  elements (i.e., the cladding panel brackets  44 / 44   a , yoke  46 , anchor bracket  48 , and clamp  50 ) is likewise appreciated upon review of FIGS. 9 &amp; 10. FIG. 9 illustrates vertical rotation of horizontally adjacent cladding panels, the weather seal in compression and spread exhibited (i.e., the right cladding panel bracket  44  rotating clockwise about its cladding panel bracket pivot  72  and to the right with respect thereto as indicated by the arrow; the left cladding panel bracket  44   a  rotating counter clockwise about its cladding panel bracket pivot  72   a  and to the left with respect thereto as indicated by the arrow); and, FIG. 10 illustrates vertical rotation of horizontally adjacent cladding panels, the weather seal in expansion and approach exhibited (i.e., the right cladding panel bracket  44  rotating counter clockwise about its cladding panel bracket pivot  72  and to the left with respect thereto as indicated by the arrow; the left cladding panel bracket  44   a  rotating clockwise about its cladding panel bracket pivot  72  and to the right with respect thereto as indicated by the arrow). 
     The horizontal linkage assembly  42  generally includes a pin or rod  118 , the opposingly paired vertical members  36  (e.g., mullions) being adapted to receive opposing portions thereof. As shown generally in FIGS. 9-10 and more particularly in FIG. 11, the pin  118  (e.g., bolt) preferably includes a threaded end  140  opposite a head  142 . It is preferable but not necessary that at least one of the opposingly paired vertical members  36  be adapted to retain at least one of the end portions of the pin  118  (e.g., head), for example by the irregular key way  120 , specifically the slot  124  through which the end portion of the pin cannot pass, as was discussed in relation to FIG.  5 . This style configuration is especially appropriate in seismic regions, where spread will result in catastrophic cladding failure. Likewise, the irregular key way  120  configuration greatly facilitates assembly of panel rows, the enlarged end portion  142  of the pin  118  being easily initially received within the pin entry aperture  122  and subsequently positioned within slot  124 . It is further preferable that the opposingly paired vertical members  36  are further adapted to secure at least one of the opposing portions of the pin  118 , as is the case for instance wherein at least one of the opposing portions of the pin  118  (e.g., bolt) is threaded for retention or anchoring by one of the opposingly paired vertical members  36 . 
     As is readily apparent from review of FIGS. 9 &amp; 10, it is critical that the horizontal linkage assembly  42  be able to accommodate the degree of spread (i.e., joint elongation) between horizontally adjacent panels. It may readily be appreciated that, under a variety of commonly encountered scenarios, the design spread may warrant a special linkage configuration, for instance the horizontal linkage assemblies of FIGS. 12 &amp; 13. 
     Referring now to FIGS. 12 &amp; 13, an articulated pin or rod  218 ,  318  respectively is shown, opposing portions thereof being generally receivable in opposing portions of adjacent vertical mullions  36 . The pin  218  is arranged in the horizontal linkage assembly  42  such that the joint (i.e., hinge)  219  of the pin  218  is interposed between the adjacent vertical mullions  36  (i.e., horizontally adjacent panels). The rod  218  of the embodiment of FIG. 12 is secured to the mullion  36 , as for instance by the integration of threads  221  of the rod end  223  with that portion of the mullion  36  adapted to receive same, whereas the rod  318  of the embodiment of FIG. 13 is not secured to either vertical mullion  36 , however, the rod length is sufficient such that opposing portions thereof will remain engaged with the portion of the mullion  36  adapted to receive same. Although the specific horizontal linkage assemblies of FIGS. 11-13 have been disclosed, variations thereof in the context of the subject self-bearing flexible curtain wall system are contemplated. 
     It will be understood that this disclosure, in many respects, is only illustrative. Changes may be made in details, particularly in matters of shape, size, material, and arrangement of parts without exceeding the scope of the invention. Accordingly, the scope of the invention is as defined in the language of the appended claims.