Abstract:
A corner drift connector for preventing damage to exterior walls of buildings during wind, earthquake, or other building-deforming events is described. The corner drift connector is slidably attached to each of two angled walls which form a corner of a building. Slots in flanges of the corner drift connector facilitate utilizing connectors to attach the corner drift connector to the walls while allowing relative motion between the walls and the connector. A cover placed outside the corner drift connector conceals the connector and its intersections with the walls.

Description:
FIELD OF THE INVENTION 
     The present invention related to the field of building construction and specifically to the aspect preventing damage to the corners of buildings in high winds, earthquakes, and other building-deforming situations. 
     BACKGROUND OF THE INVENTION 
     Seismic events, high winds, or other mechanical disturbances pose the potential for major damage and even destruction of buildings. Design practices and building codes provide mitigating approaches to building design and construction that introduce some degree of lateral flexibility in buildings. This lateral flexibility allows buildings undergoing such events or disturbances to deform without being permanently damaged in any significant way from a basic structural standpoint. This deformation takes the form generally of lateral drift of the floors of the building. Lateral drift varies from floor to floor from the bottom to the top of the building. Drift generally increases from the bottom floor to the top floor such that there is relative lateral motion between consecutive floors. Lateral drift is, however, reversible. That is, when, for example, the high winds cease, such buildings will return to basically their original shape and retain their structural integrity. Floors move laterally back to their original positions one above the other. 
     The amount of lateral drift typical in such events depends upon the particular structural form of the building. In moment frame design, where floors are supported essentially by columns spaced throughout the building, the lateral stability of the building is dependent on the bending stiffness of the columns collectively. In such building designs, lateral floor-to-floor drifts of 2 to 3 inches are common under seismic loading. In steel braced or concrete shear wall designs, lateral stability is dependent upon various kinds of cross bracing or shear walls associated with vertical supports. In such structures under the same kind of seismic event, floor-to-floor drifts of 0.5 to 0.75 inches may be experienced. 
     Walls defining areas within such buildings, and particularly exterior walls enclosing the building, are commonly non load-bearing walls. Such non load-bearing walls will, for example, enclose a space between two adjacent floors, or a part of a story of the building. Walls are never anchored to both floors which define the story. Rather, walls are anchored, for example, to the lower floor and allowed to move relative to the upper floor. Such walls must accommodate relative lateral drift between floors. Lateral drift in the plane of a wall, for example, is accommodated by a slidable attachment of the wall to the upper floor such that when the floors drift relatively, the wall slides along with the lower floor. Designs to provide such slidable attachment include slotted slip tracks or nested tracks engaging the upper portions of the walls and connecting them to the upper floors. These designs provide a degree of rotational freedom of the wall relative to both the lower and upper floors as well as lateral slidability in the plane of the wall relative to the upper floor. These and similar extant connection approaches also accommodate any vertical relative movement of the floors which may occur in connection with the various kinds of building disturbing events. The accommodation of lateral drift is, however, the major concern. 
     Lateral drift in a direction out of the plane of a wall is accompanied by a tilting of the wall in the direction of the relative lateral drift. Rotational freedom provided by the lower and upper floor wall attachments allows a degree of tilting within limits. Lateral drift within the plane of a wall is accommodated by the wall sliding relative to the upper floor. This ability to slide derives from the slidable connection mentioned above. Any in-plane separations between adjacent co-planar walls are easily accommodated by extant devices such as flexible joints, tracks, and slotted clips. Where adjacent walls are not co-planar, for example at a corner, there is a problem in maintaining the integrity and appearance of the corner. 
     The problem with angled adjacent walls is most clearly understood by considering a simple right-angled building corner and by envisioning one story of a building. The walls are anchored to the floor as described above and meet at the 90 degree corner. The walls are generally connected at the corners and provided with enclosing trim or other corner treatment to seal the walls at the corner. The walls are slidably connected to the upper floor as described above. A lateral drift of the upper floor relative to the lower floor in a direction parallel to one wall will push the top of the other wall away from the corner. The other wall remains fixed to the floor and does not move away from the corner. As the wall being pushed away by the lateral drift of the top floor tilts and/or bends a generally triangular gap will occur at the corner. The apex of the triangular gap is at the lower floor level, and the gap becomes progressively wider towards the upper floor. This gaping damages the corner structure of the wall, compromising the integrity of the closure of the wall and creating an aesthetic deficit for the building. Practical means are needed to prevent such corner damage. 
     SUMMARY OF THE INVENTION 
     The invention comprises a corner wall structure of a building fabricated to prevent or reduce damage to the corner wall structure due to high winds, earthquakes, or other building-deforming events. The corner wall structure includes first and second non load-bearing walls disposed at an angle relative to each other and thereby forming a corner of the building. The walls are each slidably connected to a corner drift connector in such a way that the walls remain connected through the corner drift connector. However, due to the slidable connections with the corner drift connector, the walls may move relative to each other and relative to the connector. 
     The invention further comprises a method of connecting non load-bearing walls at corners such that relative motion of the walls is permitted during building-deforming events. Permitting relative motion between the walls prevents or limits damage to the walls during such events. The method includes fabricating and attaching the walls to the building structure, and slidably connecting the walls at the corners utilizing the corner drift connector described above. 
     Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of such invention. 
    
    
     
       DESCRIPTION OF THE DRAWINGS ILLUSTRATING THE INVENTION 
         FIG. 1  is a fragmentary pictorial view of the corner drift connector. 
         FIG. 2  is an exploded pictorial view of a connector assembly used in one embodiment. 
         FIG. 2A  is an exploded pictorial view of an alternate connector assembly used in one embodiment. 
         FIG. 3  is a fragmentary pictorial view of a corner wall structure utilizing the corner drift connector. 
         FIG. 4  is a horizontal section view of a corner wall structure utilizing the corner drift connector. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     The present invention relates to protecting corners between non-load bearing walls of a building from damage due to events which deform the building. Such events include high winds and earthquakes as well as any event which causes relative movement, or drift, between parts of the building. Design practice and building codes aimed at making buildings safer in such events require significant mechanical flexibility in the building structure. A typical kind of flexibility designed into buildings provides for reversible lateral drift of one floor of a building relative to an adjacent floor above or below. Relative drift, depending on the severity of the event, can range up to about 3 inches. Building practice also includes the use of non load-bearing walls which are attached to portions of the building but which do not significantly participate in supporting the general building structure. These walls function principally to separate and enclose areas of the building. 
     Building walls generally extend from one floor to the floor above, thus defining the spaces, or stories, between the floors. In order to prevent major and permanent damage to floors and walls of buildings constructed with the flexibility described above, it is a common practice to fixedly attach each wall to only one floor while keeping the wall movable relative to an adjacent floor. This practice and alternative means for accomplishing it are described in more detail in the Background of the Invention. When walls are thus installed, an event which causes a floor to drift horizontally in the plane of the wall, results in the wall attached to that floor moving with the floor. This arrangement prevents the wall from being sheared and perhaps destroyed as would be the case were the wall fixedly attached to both floors. Also, walls installed in the above fashion may tilt or bend out of plane when the drift is in the out of plane direction. This tilting or bending is made possible by a pivotal flexibility built into the connection of the walls with one or more floors, and within limits this tilting of bending of the wall results in no permanent damage to the wall itself. Moreover, it is appreciated that were the walls fixedly and rigidly attached to both adjacent floors, building flexibility and the resulting protection that flexibility provides, would be reduced. 
     There is, however, a problem that derives from the above described approach to building construction. The problem is illustrated, for example, in the case of exterior walls of a building. When first and second exterior walls are fixedly attached to the same floor and when they are at an angle to each other, the walls intersect forming a corner. This corner is seen as a generally vertical intersection of the two walls. When one floor moves horizontally relative to an adjacent floor and in a direction parallel to a first wall, for example, then this first wall moves in-plane and with the floor, sliding relative to the adjacent floor. The second wall, however, is constrained at its top to move out of plane and with the floor above while it moves out of plane at its bottom with the floor below thereby tilting. In such a case, the corner fails by breaking apart, forming a generally triangular gap between the walls at the corner. When the event causing the building deformation ends and the floors return to their normal positions. The triangular gap may partially close, but the damage to the corner is permanent, and the integrity of the building closure provided by the walls is compromised. 
     Turning now to a detailed description of the present invention and its application to solve the problem described above, it is first useful to establish some definitions of pertinent terms associated with the invention. These terms and their definitions are listed below:
         Non load-bearing wall: a wall which carries no load associated with supporting the building structure or maintaining its overall structural integrity. That is, a non load-bearing wall serves only to enclose and separate areas of a building. An example of such a wall may be found defining the exterior of a building; however, not all exterior walls are non load-bearing.   Corner wall structure: a structure forming a generally vertical intersection of two building walls which are disposed relative to each other at any angle other than 180 degrees.   Finish wall structure: materials assembled and applied adjacent a surface of a wall having the principal function of concealing the interior structure and providing a desirable outside appearance of the surface. Such materials may include brick, stone, concrete panels, stucco, wood, and etc.   Corner drift connector: a device which allows reversible and non-destructive relative horizontal motion between two walls which meet at a corner.       

     Referring to the  FIG. 1 , the present invention includes a corner drift connector, indicated generally by the numeral  10 , associated with a plurality of connector devices. Corner drift connector  10  includes a pair of flanges  12  and  14  extending at an angular relationship with each other and forming a generally vertical juncture  18 . A series of spaced-apart slots  16  is disposed in each of flanges  12  and  14  and oriented generally horizontally relative to juncture  18 . Slots  16  may be of any length, but are preferably up to about 6 inches long. Slot  16  may be of any width suitable for engaging the connector devices as further described below. In one embodiment the connector devices comprise shouldered connectors indicated generally by the numeral  32 , each including a screw head  32 C, a shoulder  32 B, and a screw shaft  32 A. The length of shoulder  32 B is slightly greater than the thickness of flanges  12  and  14 . When disposed in slot  16 , shoulder  32 B is slidable along the slot. In another embodiment, illustrated in  FIG. 2 , the connector devices include shouldered connector assemblies indicated generally by the numeral  34 , each comprising a bushing  34 B and a screw which includes a screw head  34 C and a screw shaft  34 A. The length of bushing  34 B is slightly greater than the thickness of flanges  12  and  14 . When shouldered connector assembly  34  is disposed in slot  16 , screw shaft  34 A penetrates bushing  34 B, and the bushing is slidable along the slot. Relative to each of the above two embodiments, diameters of screw heads  32 C and  34 C are larger than the width of slot  16 . In an additional embodiment, shown in  FIG. 2A , the connector devices include stepped bushing connector assemblies indicated generally by the numeral  36 , each comprising a stepped bushing  36 B and a screw which includes a screw head  36 C and a screw shaft  36 A. Stepped bushing  36 B includes a flange  36 E and a stepped down portion  36 D. The diameters of stepped down portion  36 D and flange  36 E are such that the stepped down portion can be disposed within slot  16  and the flange can abut corner shift connector  10  and extend above and below the slot. The length of stepped down portion  36 D is slightly greater than the thickness of flanges  12  and  14 . When stepped bushing connector assembly  36  is disposed in slot  16 , screw shaft  36 A penetrates stepped bushing  36 B, and the stepped bushing is slidable along the slot. 
     Corner drift connector  10  forms a part of a corner wall structure, indicated generally by the numeral  20  and illustrated in  FIGS. 3 and 4 . Corner wall structure  20  is a part of a building structure comprising at least a lower floor  62  and an upper floor  64 . Floors  62  and  64  are supported by conventional building structural elements such as columns spaced throughout the building. Enclosing a portion of the building are first and second non load-bearing walls  50  and  50 A disposed at an angle to each other and engaged with floors  62  and  64 . Walls  50  and  50 A are spaced apart from each other so that they do not intersect and form a corner; rather, the planes of the walls  50  and  50 A intersect, but a gap between the walls is maintained. Each wall  50  and  50 A comprises a series of studs  52  spaced apart and oriented generally vertically. Stud lower ends  52 C are held in lower track  54 , and stud upper ends  52 D and held in upper track  56 . Lower track  54  is fixedly attached to lower floor  62 . Upper track  56  is slidably engaged with upper guide or track  58 , and the upper guide is fixedly attached to upper floor  64 . Sheathing  59  is attached to studs  52  completing the fundamental structure of walls  50  and  50 A. 
     Corner drift connector  10  is disposed adjacent walls  50  and  50 A such that flanges  12  and  14  engage walls  50  and  50 A. Flanges  12  and  14  lap sheathing  59  and are fastened thereto by a plurality of connector devices. In one embodiment, the connector devices comprise shouldered connectors  32  which are inserted through slots  16  such that screw shafts  32 A penetrate sheathing  59 . Shoulder  32 B is thus slidable within slots  16  and flanges  12  and  14  are guided between screw heads  32 C and sheathing  59 . In another embodiment the connector devices include shouldered connector assemblies  34  which are inserted through slots  16  such that screw shafts  34 A penetrate sheathing  59 . Bushings  34 B are slidable within slots  16 , and flanges  12  and  14  are guided between screw heads  34 C and sheathing  59 . Thus disposed, corner drift connector  10  extends between, and is slidably connected to, walls  50  and  50 A. Corner drift connector  10  is thus secured to sheathing  59  while slidable relative to the sheathing. 
     Walls  50  and  50 A are finished by applying one or more finish wall structures  70  to the walls. Finish wall structures  70  may be connected to walls  50  and  50 A by any of a number of conventional means. Connection of finish wall structures  70  may include spacing the finish wall structures outwardly from sheathing  59  to provide an air space therebetween. Finish wall structures  70  may comprise bricks, stone, wood, or other decorative material. The finish wall structures  70  extend to the vicinity of corner drift connector  10 , but may not intersect. Rather, spacing is maintained around the corner and between the finished wall structures  70  of the two walls  50  and  50 A. This spacing is a gap which permits the finished wall structures  70  to move relative to each other and allows changes in the gap between walls  50  and  50 A and between the finished wall structures of the walls. 
     The gap, or space, between the finished wall structures  70  is concealed by a cover  40  disposed outside corner drift connector  10  and engaged with the finish wall structures. In one embodiment, cover  40  is constructed of a flexible, compliant material and is sealed or otherwise fixedly attached to finished wall structures  70  by utilizing an adhesive. In another embodiment, cover  40  is attached to corner drift connector  10 , and portions of the cover may lap outside finish wall structures  70  sufficiently to conceal any gap occurring at the corner. Thus installed, cover  40  conceals corner drift connector  10  and areas of sheathing  59  adjacent the corner drift connector. 
     Corner wall structure  20 , described above, functions to prevent corner damage which may result from high winds, earthquakes, or other building-deforming events. Damage is prevented by the accommodating relative motion between walls  50  and  50 A with flexibility of corner wall structure  20  as further described herein. Relative horizontal motion, or drift, as a result of such events, occurs between lower floor  62  and upper floor  64  occurs, and walls  50  and  50 A move relative to each other. More particularly, when the relative motion of the floors  62  and  64  is directed horizontally and parallel to wall  50 A, walls  50  and  50 A move in different ways. Wall  50 A drifts horizontally and in-plane, moving with lower floor  62  and sliding relative to upper floor  64 . Wall  50  tilts in the direction of the relative motion because upper stud ends  52 D in wall  50  move with upper floor  64  while lower stud ends  52 C move with lower floor  62 . Thus, wall  50 A drifts away from the corner while wall  50  tilts, forming a generally triangular gap between the walls. Slots  16  in flanges  12  and  14  of corner drift connector  10 , however, allow connector devices  30  to slide therein, maintaining the connection of flanges  12  and  14  to gapped-apart walls  50  and  50 A and thus assuring the integrity of corner wall structure  20 . Moreover, cover  40  keeps corner drift connector  10  and the gap between walls  50  and  50 A concealed. In one embodiment, cover  40  deforms to keep to concealment of the corner intact, while in another, a portion of the cover laps finish wall structure  70  sufficiently to keep the gap concealed. When the building-deforming event ends, the floors return their original alignment. The slidable connection of corner drift connector  10  to walls  50  and  50 A allow the walls to return to their original angular orientation to each other, and the corner is undamaged. Thus, after a high wind, seismic, or other building-deforming event, the slidable connections included in corner wall structure  20  allow the corner to be reversibly deformed and return to its original shape in an undamaged condition. 
     The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the scope and the essential characteristics of the invention. The present embodiments are therefore to be construed in all aspects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.