Abstract:
A hanger assembly and method of hanging conduits in buildings is described which protects the structure of the building from damage during a seismic event. The hanger assembly includes a frangible element which is calibrated to break when subjected to some higher than normal tensile load resulting from rapid acceleration of the conduit. Thus, for example, in the event of an earthquake, the hanger will fail before damage is done to the concrete to which the anchor is attached.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/176,753, filed Feb. 26, 2015, hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an apparatus and method for building construction, and more particularly to an apparatus and method to protect building during seismic events. 
         [0004]    2. Discussion of the Background 
         [0005]    The pervasive style of providing services in commercial buildings is to vertically suspend the services from the underside of an overhead structure using hangers. Thus, for example, plumbing or electrical wiring can be provided into the interior of building by way of conduits that hang from structural elements of the building. Thus, for example, electrical conduits, plumbing pipes, sprinkler pipes, or mechanical piping systems are installed just below a ceiling. The services thus provide are referred to herein, without limitation, as “conduits” supported by “hangers.” 
         [0006]    When the overhead structure is a concrete slab or formed metal decking filled with concrete, a concrete-type anchorage is placed into the structure. Concrete-type anchorages include an element (referred to herein collectively as “anchor”) that is typically a drill-in, shoot-in or glue-in type anchorage that is installed after the concrete has set, or a cast-in-place type anchorage that is positioned prior to the concrete being poured, so that it becomes cast into the finished concrete. The anchor typically presents a male threaded projection or female threaded aperture. In either instance the anchor would thus allow for a threaded connection to the structure. 
         [0007]    The conduit is usually supported at multiple locations along its routing by a hanger, clamp or trapeze (referred to herein collectively as “bracket”) that cradles or supports the conduit. Brackets come in many forms and vary depending on the type and/or size and/or quantity of the conduit. 
         [0008]    The anchor and bracket are generally connected with a threaded rod, rod, cable, angle iron, strut channel or tubular material (referred to herein collectively as “connector”). The connector may include one or more elements disposed between the anchor and bracket to form a tension member that secures the conduit to the structure. 
         [0009]    Movement of the earth or building in the event of an earthquake, explosion, impact or other types of events can greatly increase the load on the hanger. Thus for example, up and down ground motion during a seismic event can result in a rapidly varying anchor load, which is transferred to the supporting concrete. This load increase can cause the concrete to fail near the location of the anchor. Due to the large number of anchors in a building, the building structure may be threatened. 
         [0010]      FIG. 1A  is an elevational side view of a prior art conduit hanger assembly  10  installed to support a conduit  12  from the underside of a concrete deck  14 . Conduit hanger assembly  10  includes an anchor  16  which may be placed in deck  14 , a threaded rod  21  extending downwards from the anchor, a connector assembly  20  including a threaded rod  22 , and threaded nuts  26  which support bracket  18  from threaded rod  22 . Connector assembly  20  also includes a threaded link  24  which is used to attach threaded rod  21  and threaded rod  22 . 
         [0011]      FIG. 1B  is the view of  FIG. 1A  where prior art conduit hanger assembly  10  is subjected to a sufficient force to cause the hanger assembly to fail. Typically, the weakest component in suspended hanger assembly  10  is the concrete, which will fail in tension. During a seismic event, for example, conduit  12  may move vertically, imparting a tension force on hanger assembly  10 , as indicated by arrow F. In the example of  FIG. 1B , the tension is sufficient for anchor  16  to cause the concrete in deck  14  to fail, resulting in failed causing the anchor  16  and a portion of the concrete  17  to break and/or pull away from the building. In most cases the strength of the concrete in this and adjacent area is irreparably damaged. After a seismic event it is possible to have many such anchor failures rendering portions of the building unsalvageable. 
         [0012]    Thus there is a need in the art for a method and apparatus that permits conduits to be provided to buildings that can also protect the buildings from damage to seismic or impact loading. Such a method and apparatus should be easy to use, be compatible with current construction techniques, should provide for retro-fitting of existing installations and should be inexpensive. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    Embodiments presented herein overcome the disadvantages of prior art by providing a hanger assembly with a frangible element. 
         [0014]    It is one aspect to provide a method of preventing damage to concrete deck that supports a load from a conduit, where the concrete deck is damaged if the supported load exceeds a maximum load. The method includes supporting the conduit from the concrete deck with a hanger assembly attached to the concrete deck, where the hanger assembly includes a frangible element that supports the weight of the conduit by the concrete deck, and where, if an event occurs which increases the force on the anchor from the conduit, the frangible element undergoes a ductile fracture before the supporting concrete is damaged. 
         [0015]    It is another aspect to provide a hanger assembly attachable to an anchor affixed in a concrete deck, where the anchor damages the concrete deck if the hanger assembly supports more than a maximum load. The hanger assembly includes: a first hanger assembly end attachable to the anchor; a second hanger assembly end having a hanger for supporting a conduit; and a frangible element between the first hanger assembly end and the second hanger assembly end, where the frangible element undergoes a ductile fracture at a load that is less than the maximum load, such that the breakage of the frangible element prevents damage to the concrete deck. 
         [0016]    It is yet another aspect to provide a hanger assembly attachable to an anchor affixed in a concrete deck and having a hanger to accept a conduit, where the anchor damages the concrete deck if the hanger assembly supports more than a maximum load. The hanger assembly includes: a frangible element having a first frangible element end and a second frangible element end; a first link including a first frangible element receiving portion to receive the first frangible element end; a user placeable first fastener to attach the first frangible element receiving portion and the received first frangible element end; a second link including a second frangible element receiving portion to receive the second frangible element end; and a user placeable second fastener to attach the second frangible element receiving portion and the received second frangible element end. The frangible element fails at a load that is less than the maximum load, such that the breakage of the frangible element prevents damage to the concrete deck. 
         [0017]    These features together with the various ancillary provisions and features which will become apparent to those skilled in the art from the following detailed description, are attained by the vaporizer of the present invention, preferred embodiments thereof being shown with reference to the accompanying drawings, by way of example only, wherein: 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0018]      FIG. 1A  is an elevational side view of a prior art conduit hanger assembly installed to support a conduit from the underside of a concrete deck; 
           [0019]      FIG. 1B  is the view of  FIG. 1A , where the prior art conduit hanger assembly is subjected to a sufficient force to cause the hanger assembly to fail; 
           [0020]      FIG. 2A  is an elevational view of a first embodiment connector assembly installed to support a conduit from a concrete deck; 
           [0021]      FIG. 2B  is the view of  FIG. 2A , where the conduit hanger assembly is subjected to a sufficient force to cause the hanger assembly to fail; 
           [0022]      FIG. 3A  is a perspective view of the one embodiment of a connector link; 
           [0023]      FIG. 3B  is a front elevational view of the connector link of  FIG. 3A ; 
           [0024]      FIG. 3C  is a side elevational view of the connector link of  FIG. 3A ; 
           [0025]      FIG. 3D  is a top plan view of the connector link of  FIG. 3A ; 
           [0026]      FIG. 3E  is a bottom plan view of the connector link of  FIG. 3A ; 
           [0027]      FIG. 4A  is a front elevational view of a second embodiment connector link; 
           [0028]      FIG. 4B  is a side elevational view of the connector link of  FIG. 4A ; 
           [0029]      FIG. 5A  is a front elevational view of a third embodiment connector link; 
           [0030]      FIG. 5B  is a side elevational view of the connector link of  FIG. 5A ; 
           [0031]      FIG. 6A  is a side elevational view of the connector link of  FIGS. 4A and 4B  attached to a concrete anchor; 
           [0032]      FIG. 6B  is a side elevational view of the connector link of  FIGS. 5A and 5B  cast into a concrete structure; 
           [0033]      FIG. 7A  is a sectional view  7 A- 7 A of  FIG. 2A , where connector piece  42 , is a length of electrical conduit disposed in the gap  46  of the legs  45 ; 
           [0034]      FIG. 7B  is similar to  FIG. 7A , where connector piece  42  is a length of pipe  72 ; 
           [0035]      FIG. 7C  is similar to  FIG. 7A , where connector piece  42  is a length of rectangular tubing  74 ; 
           [0036]      FIG. 7D  is similar to  FIG. 7A , where connector piece  42  is a length of strut channel  76 ; 
           [0037]      FIG. 7E  is similar to  FIG. 7A , where connector piece  42  is a length of an angle piece  78 . 
           [0038]      FIG. 8A  is a front elevational view of the preferred embodiment of the inventive connector link assembly, wherein the calibrated connection is at the proximal end of the connector assembly; 
           [0039]      FIG. 8B  is a side elevational view of the preferred embodiment of the inventive connector link assembly; 
           [0040]      FIG. 8C  is a side elevational view of the preferred embodiment of the connector element of the inventive connector link assembly shown in  FIG. 8B ; 
           [0041]      FIG. 8D  is a side elevational view of the preferred embodiment of the connector element of the inventive connector link assembly shown in  FIG. 8B  after tension force of the assembly starts to distort the connection element; 
           [0042]      FIG. 9A  is a front elevational view of the preferred embodiment of the inventive connector link assembly after the tension force quotient has been exceeded; 
           [0043]      FIG. 9B  is a side elevational view of the preferred embodiment of the inventive connector link assembly after the tension force quotient has been exceeded; 
           [0044]      FIG. 10A  is a perspective view of an first alternative embodiment of a connector link; 
           [0045]      FIG. 10B  is a front elevational view of the connector link of  FIG. 10A ; 
           [0046]      FIG. 10C  is a side elevational view of the connector link of  FIG. 10A  attached to a concrete anchor; 
           [0047]      FIG. 11A  is front elevational view a second alternative embodiment of connector link; 
           [0048]      FIG. 11B  is a top plan view of the connector link of  FIG. 11A ; 
           [0049]      FIG. 11C  is a side elevational view of an upper connector link of  FIG. 11A  attached to concrete anchor; 
           [0050]      FIG. 12A  is a front elevational view of the second alternative connector link  44  of  FIG. 11A  with a clevis-type attachment; 
           [0051]      FIG. 12B  is a side elevational view of the connector link attachment of  FIG. 12A ; 
           [0052]      FIG. 12C  is a front elevational view of the connector link attachment of  FIG. 12A  attached to a concrete anchor; 
           [0053]      FIG. 13A  is a front elevational view of a first alternative embodiment connector link assembly; 
           [0054]      FIG. 13B  is a front elevational view of a second alternative embodiment connector link assembly; 
           [0055]      FIG. 13C  is a front elevational view of a third alternative embodiment connector link assembly; 
           [0056]      FIG. 14A  is a side elevational view of the connector link assembly with indicia that establishes the initial location of the inventive connector link relative to an attached connector piece; 
           [0057]      FIG. 14B  is a side elevational view of the connector link assembly of  FIG. 14A  after a seismic event; 
           [0058]      FIG. 15A  is a side elevational view of the connector link assembly with alternative indicia that establishes the initial location of the inventive connector link relative to an attached connector piece; 
           [0059]      FIG. 15B  is a side elevational view of the connector link assembly of  FIG. 15A  after a seismic event; 
           [0060]      FIG. 16  is an elevational view of an installed alternative conduit hanger assembly with two connector link assemblies in series; 
           [0061]      FIG. 17  is an elevational view of an installed other alternative conduit hanger assembly with one connector link; 
           [0062]      FIG. 18  is an elevational view of an installed version of yet another conduit hanger for suspending a conduit; and 
           [0063]      FIG. 19  is an elevational view of an installed version of another conduit hanger for suspending several conduits. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0064]    The following description provides embodiments of apparatus that provide protection for building subject to events that increase the load on conduit hangers. Specifically, methods and apparatuses for supporting conduits using frangible hanger assemblies are described. Such methods and apparatus allow the conduit hanger to fail before the buildings to which they are attached. 
         [0065]      FIG. 2A  is an elevational view of a first embodiment conduit hanger assembly  30  installed to support conduit  12  from concrete deck  14 . Conduit hanger assembly  30  includes anchor  16  which may be placed within concrete deck  14 . Anchor  16  can, in general, be a drill-in, shoot-in or glue-in type anchor for attaching to poured concrete or a cast-in-place type anchorage that is set into the concrete during pouring. 
         [0066]    Anchor  16  is attached to a first threaded rod  21  that extends downwards from the anchor, and a connector assembly  32  attached to the first threaded rod and which supports bracket  18 . More specifically, connector assembly  32  includes a connector link assembly  40  threadable into first threaded rod  21  and threaded rod  22  and threaded nuts  26  which are used to support bracket  18 . 
         [0067]    Connector link assembly  40  and the various embodiments and combinations described here function as a tension component for supporting conduits up to some maximum load. When the maximum load is exceeded, the connector link assembly  40 , which is frangible breaks. In certain embodiments, the connector link assembly  40  breaks by a ductile fracture. This invention facilitates the design of utility hanger assemblies and the like so that in the serial chain of components supporting a load, the link assembly will meet the load requirements and be the first to fail in an overload condition. 
         [0068]    Connector link assembly  40 , as discussed subsequently in greater detail, includes a connector piece  42  having a first end  421  and a second end  423 , and a pair of connector links shown as an upper link  44 A having a first end  441 A and a second end  443 A, and a lower link  44 B having a first end  441 B and a second end  443 B. First end  441 A has internal threads and is threadably connected to threaded rod  21  and second end  443 A is attached to first end  421  using fastener(s)  53 . First end  441 B has internal threads and is threadably connected to threaded rod  22  and second end  443 B is attached to second end  423  using fastener(s)  51 , as discussed subsequently. 
         [0069]    Conduit hanger assembly  30  is designed to be able to hold the load of conduit  12  from concrete deck  14  and, in the case of a sufficiently large tensile force, fail before the concrete fails. In this way, conduit hanger assembly  30  does not damage the integrity of concrete deck  14 . 
         [0070]    In certain embodiments, connector link assembly  40  undergoes testing to determine the maximum load that it may support in a seismic event. The actual tests may vary according to local building codes. In general, one may determine a maximum permissible load for any configuration of connector link assembly  40  by, for example, seismic testing. 
         [0071]    Thus, in one embodiment, connector piece  42  is frangible and, specifically, is designed to be the weakest part of conduit hanger assembly  30  under tension.  FIG. 2B  is the view of  FIG. 2A , where connector piece  42  is subjected to a sufficient force to fail before the concrete deck fails. The inventive conduit hanger assembly  30  thus fails with a break in connector piece  42 , leaving anchor  16 , threaded rod  21 , and upper link  44 A attached to concrete deck  14 . This is in contrast to the prior art conduit hanger assembly, as shown in Prior Art  FIG. 1B . 
         [0072]    The failure of connector piece  42  near upper connector link  44 A is illustrative, and the failure mode of conduit hanger assembly  30  may be at some other place in the conduit hanger assembly, such as in connector piece  42  near lower connect link  44 B, some other location in the connector piece, or some other location within the conduit hanger assembly that does not result in damage to concrete deck  14 . 
         [0073]    In certain embodiments, connector links  44 A and  44 B are identical, and are shown in  FIGS. 3A through 3E  as one embodiment of a connector link  44 , where  FIG. 3A  is a perspective view,  FIG. 3B  is a front elevational view,  FIG. 3C  is a side elevational view of the connector link of  FIG. 3A ,  FIG. 3D  is a top plan view, and  FIG. 3E  is a bottom plan view. Connector link  44  has a first end  4401 , which is generally similar to first ends  441 A and  441 B of  FIG. 2A  and a second end  4403 , which is generally similar to second ends  443 A and  443 B of  FIG. 2A . First end  4401  has a bore  49  that is threaded to accept a male threaded rod, stud or bolt, such as a threaded rod  21  or  22 , and two legs  45  defining a narrow gap  46  (as, for example, second ends  443 A and  443 B of  FIG. 2A ) between the two legs, and transverse holes  47  through legs  45  that align on either side of the gap  46 . While  FIGS. 3A, 3B, and 3C  show two holes  47 , various embodiments may have one hole or may have three or more holes. 
         [0074]    First end  4401  also includes an upper portion  48  which is hexagonally shaped along a longitudinal axis to facilitate cooperation with wrenches and tools for engagement and tightening a threaded connection. Alternatively, upper portion  48  may be cylindrical, square or other shape depending on the type of connection method. The gap  46  is designed to accept a connector piece, such as connector piece  42 . In certain embodiments, an end of gap  46  provides a seat against which connector piece  42  rests when the connector piece is fully inserted into gap  46 . A pin placed through transverse hole  47  can also pass through a hole in the connector piece  42 , as discussed subsequently, for retaining connector piece  42 . Fastener(s)  51  and  53  and transverse hole  47  may, in alternative embodiments, be unthreaded, partially threaded, or threaded throughout. 
         [0075]    In a second embodiment conduit hanger assembly, connector link  44 A and first threaded rod  21  of conduit hanger assembly  30  are replaced with a second embodiment connector link  54 , which combines the function of connector link  44 A and the first threaded rod  21 .  FIG. 4A  is a front elevational view of second embodiment connector link  54 , and  FIG. 4B  is a side elevational view of the connector link of  FIG. 4B . Connector link  54  is generally similar to connector link  44  and first threaded rod  21 , except as explicitly stated. 
         [0076]    Connector link  54  has a first end  5401  and a second end  5403 . First end  5401  includes an integral or attached threaded stud  56  that is threadable into anchor  16 . Second end  5403  is generally similar to second end  4403  and supports connector piece  42 .  FIG. 6A  is a side elevational view of the connector link of  FIGS. 4A and 4B  attached to a drill-in type anchor  16 . 
         [0077]    In a third embodiment conduit hanger assembly, connector link  44 A, first threaded rod  21 , and anchor  16  of conduit hanger assembly  30  are replaced with a third embodiment connector link  64 , which combines the function of connector link  44 A, the first connector rod, and the anchor.  FIG. 5A  is a front elevational view of a third embodiment connector link  64 , and  FIG. 5B  is a side elevational view of the connector link. Connector link  64  is generally similar to connector link  54  and/or  44 , except as explicitly stated. 
         [0078]    Connector link  64  includes an anchor  66 , at a first connector link end  6401 , and two legs  45  defining a narrow gap  46  at a second connector link end  6403 . Anchor  66  of first connector link end  6401  can be anchored directly in the concrete pour of concrete deck  14 , and second connector link end  6403  can support connector piece  42 .  FIG. 6B  is a side elevational view of the connector link of  FIGS. 5A and 5B  cast into a concrete deck  14 . 
         [0079]    A wide variety of geometries may be used for connector piece  42 . Thus, for example and without limitation,  FIG. 7A  is a sectional view  7 A- 7 A of  FIG. 2A , where connector piece  42 , is a length of electrical conduit disposed in the gap  46  of the legs  45  Legs  45  may which may be, for example and without limitation, the legs of connector link  44 ,  54 , or  64 . As further examples of connector piece  42 :  FIG. 7B  is similar to  FIG. 7A , where connector piece  42 is a length of pipe  72 ;  FIG. 7C  is similar to  FIG. 7A , where connector piece  42 is a length of rectangular tubing  74 ;  FIG. 7D  is similar to  FIG. 7A , where connector piece  42 is a length of strut channel  76 ; and  FIG. 7E  is similar to  FIG. 7A , where connector piece  42 is a length of an angle piece  78 . 
         [0080]      FIGS. 8A, 8B, and 8C  are illustrative of one method of assembling the pieces of connector assembly  40  using connector piece  42 .  FIG. 8C  is a side view of connector piece  42 , and  FIGS. 8A and 8C  are a front elevation view and side elevational view, respectively, of connector assembly  40 . It will be appreciated that the following description applies, for example and without limitation, to any of the other connector pieces, such as connector piece  42 ,  74 ,  76 , or  78 . 
         [0081]    As shown in  FIG. 8C , connector piece  42  has, or is provided with, one or more holes  52  and, as shown in  FIGS. 8A and 8B , connector piece  42  is attached to links  44 A and  44 B by placing each end of connector piece  42  is positioned all of the way into gap  46  of each connector link  44 . Next, fastener(s)  51  and  53 , which may be, for example, one or more fasteners  50  which are self-drilling, self-tapping, standard threaded, pins or rivets. In any case, hole or holes  52  in connector piece  42  are provide to will align with holes  47  in the connector links  44 A/ 44 B. In certain embodiments, hole  52  is positioned at a predetermined distance D from first end  421  by pre-drilling the hole. In the embodiments, where hole  52  is not pre-drilled, connection piece  42  may be inserted into gap  46  such that a desired distance D is achieved by advancing the fastener into the connection piece. 
         [0082]    In certain embodiments, the distance D determines when connection piece  42  fails, as shown in  FIG. 2B . Since larger distances D correspond to a higher load before failure, a user may select a distance D that determines when conduit hanger assembly  30  will fail under a tensile load. 
         [0083]    One example of the desired structural failure of frangible connector piece  42 , which is not meant to limit the scope of the present invention, is illustrated in  FIGS. 8C, 9A, and 9B , where  FIG. 8C  is a side view of connector piece  42  prior to failure, and  FIGS. 9A and 9B  are a front elevation view and side elevational view, respectively, of connector assembly  40  after the structural failure of connector piece  42 . Regardless of how hole  52  is formed, under a sufficient tensile load, the hole may first elongate as it undergoes ductile fracture, as shown in  FIG. 8D . As the load increases, connector assembly  40  will ultimately fail when the strength of the connector assembly is exceeded, as shown in  FIGS. 9A and 9B . 
         [0084]    In certain embodiments, the maximum load which connector assembly  40  may support is determined by several parameters, which may be, for example, the thickness T of connector piece  40  (see FIGS. 7 A- 7 E), the material of the connector piece, the distance D between hole  52  and first end  421 , and details of fastener  50 , such as the fastener size and material. 
         [0085]    Thus, as described above, failure loads for specific connector assembly  40  may be determined as a function of the various parameters noted in the previous paragraph (fastener type, thickness, materials, hole locations and diameters, etc.). The selection of parameters thus provides a calibration indicating the failure of the connector assembly and a user can be provided with configurations which may fail at certain loadings. 
         [0086]      FIGS. 10A-10C  illustrate a first alternative embodiment of connector link  44  of  FIG. 3A  including aperture  82  at upper portion  48 , where  FIG. 10A  is a perspective view,  FIG. 10B  is a front elevational view, and  FIG. 10C  is a side elevational view of the connector link as upper connector link  44 A attached to a concrete anchor  16 . First alternative connector link  44  may, in general, be used as upper link  44 A or lower link  44 B. 
         [0087]    Aperture  82  intersects the bore  49 , and may alternatively continue through the opposite side of upper portion  48 . Aperture  82  permits visual inspection of the engagement of anchor  16  threads, as shown in  FIG. 10C . 
         [0088]      FIGS. 11A-11C  illustrate a second alternative embodiment of connector link  44  of  FIG. 3A  including a threaded aperture  82 A, where  FIG. 11A  is front elevational view,  FIG. 11B  is a top plan view, and  FIG. 11C  is a side elevational view of the connector link as upper connector link  44 A attached to concrete anchor  16 . Second alternative connector link  44  may, in general, be used as upper link  44 A or lower link  44 B. 
         [0089]    Connector link  44  of  FIGS. 11A-11C  is useful for further securing the connector link to anchor  16 . Threaded aperture  82 A can accept a threaded fastener  86  that can act as a set-bolt when tightened against a rod inserted into a bore  49 A, which may be threaded or non-threaded. 
         [0090]    As in the second alternative embodiment link  44 , aperture  82 A may pass through upper portion  48  to bore  49 A, or may pass through the opposite wall. The set-screw arrangement will work well securing non-threaded rods. 
         [0091]      FIGS. 12A-12C  illustrate the second alternative embodiment connector link  44  of  FIG. 11A  with a clevis-type attachment, where  FIG. 12A  is a front elevational view,  FIG. 12B  is a side elevational view, and  FIG. 12C  is a front elevational view of the connector link attached to concrete anchor  16 . 
         [0092]      FIGS. 12A-12C  show the second alternative embodiment connector link  44 A of  FIG. 11A  and a clevis  94 , formed by the combination of a U-shaped bracket  90 , a bolt  88  and a nut  89  pivotally attached to the connector link at aperture  82 . The top of bracket  90  includes an aperture  92  to allow connection to anchor  16  or other components in a hanger assembly. 
         [0093]      FIGS. 13A, 13B, and 13C  are front elevational views of a first, second, and third alternative embodiment of connector assembly  40 . From either calculations or from trial-and-error, the amount of tensile load required for connector piece  42  to fail at that location can be determined, and can be considered to be a calibrated strength of conduit hanger assembly  30 . 
         [0094]    In the embodiment of  FIG. 13A , there are two fasteners  53  near first end  421  and one fastener  51  located a distance D 1  from second end  423 . With this embodiment, the weakest part of connector piece  42  is between second end  423  and the hole that is at the distance D 1  from the second end. 
         [0095]    In the embodiment of  FIG. 13B , there is one fasteners  53  located a distance D 2  from first end  421  and two fasteners  51  located near second end  423 . With this embodiment, the weakest part of connector piece  42  is between first end  421  and the hole that is at the distance D 2  from the first end. 
         [0096]    In the embodiment of  FIG. 13C , there is one fasteners  53  located a distance D 2  from near first end  421  and one fastener  51  located a distance D 3  from second end  423 . For this embodiment, the distances D 2  and D 3  determine the load factor at each end of the connector piece. 
         [0097]      FIG. 14A  is a side elevational view of any of the connector link assemblies described herein with indicia  100 . Thus, for example, connector link assembly  40  of  FIG. 13B  is shown with indicia  100  on connector piece  42 . A user may user indicia  100  to align connector piece  42  with end  4403  of upper link  44 A, prior to inserting one fastener  53 . This allows the user to be sure that the proper spacing is provided for fastener  53 . 
         [0098]    Another advantage of indicia  100  is shown in  FIG. 14B , which shows connector link assembly  40  after a seismic event that did not result in the complete failure of connector piece  42 . Thus, for example, if there is partial tearing of connector piece  42 , connector link assembly  40  may stretch without breaking. Thus, upper link  44 A and lower link  44 B may, as a result of the stretching or tearing of connector piece  42 , move apart by a distance  102 , as a user would clearly see by inspection of the connector piece as shown in  FIG. 14B . 
         [0099]    An alternative indicia  106  is shown in  FIG. 15A , which is a side elevational view of the connector link assembly  40  with alternative indicia as a sprayed-on contrast such as paint or dye. Indicia  106  has the similar benefits as indicia  100 , in that it can be used to align connector link assembly  40 , as in  FIG. 15A . Further, as shown in  FIG. 15B , which is a side elevational view of the connector link assembly of  FIG. 15A  after a seismic event (as in  FIG. 14B ), a gap  108  in indicia  106  is easily seen to indicate structural damage to connector piece  42 . 
         [0100]    The conduit hanger assembly component described herein are easily arranged and adapted to support conduits in a building. Typically, the location and run of utilities in a building are only generally specified by the building designers, and installers came decide how to make each hanger for each location. Thus, for example, the connector links described herein could be provided to a job site in bulk, and connector link assemblies could be entirely made on-site with commonly available material for connector pieces. As a result, frangible conduit hanger assemblies could be easily constructed in most circumstances for a variety of applications and situations.  FIGS. 16, 17, 18, 19, and 20  illustrate a few of the many examples of applications of the inventive frangible members. 
         [0101]      FIG. 16  is an elevational view of an installed alternative conduit hanger assembly  120  with two connector link assemblies  40  in series.  FIG. 17  is an elevational view of an installed other alternative conduit hanger assembly  140  with one link  44 . Conduit hanger assembly  130  includes a connector piece  42  that is attached directly to bracket  18  without an intervening lower bracket.  FIG. 18  is an elevational view of an installed version of yet another conduit hanger  150  with inventive links  40  as used for supporting ducting  152 .  FIG. 19  is an elevational view of an installed version of another conduit hanger  160  as used for supporting a trapeze  152  including several conduits. 
       EXAMPLES 
       [0102]    The following examples are results of tests on several embodiments described herein. Specifically, conduit hanger assembly  30 , as in  FIGS. 2A and 2B  was tested with a ½ inch anchor  16  and for various dimensions of connector piece  42 . 
         [0103]    It was previously determined that, for a bolt  16  comprising a ½ inch diameter, a TRUBOLT+ Carbon Steel Seismic Wedge Type Anchor (ITW Commercial Construction, Glendale Heights, Ill.) will fail under tension with a load of 8,925 lbs. When the bolt has an embedment of 3½ inches into a minimum concrete thickness of 6 inches, the concrete surrounding an embedded bolt will fail at a Cracked Concrete Strength of 5,455 lbs. Including a factor of safety, which are required by building codes, the maximum load on such an anchor must be less than 2,659 lbs. 
         [0104]    Tests were performed on by placing threaded rods  21  and threaded rod  22  of conduit hanger assembly  30  in tension of increasing amounts until the assembly failed. If the conduit hanger assembly  30  fails under a load less than 2,659 lbs., then the conduit hanger assembly can safely be used to support loads without causing failure of the concrete. 
         [0105]    A number of conduit hanger assemblies  30 , similar to that of  FIGS. 2A and 2B  were assembled. In each conduit hanger assembly, connector piece  42  was formed from electrical metallic tubing (EMT) conduit, which is a commonly available thin-walled steel tube having a circular cross section. Specifically, tests were conducted with EMT conduit sizes of ¾″, 1″, 1¼″, 1½″ and 2″, with one fastener  53 , which was a ¼ inch screw that was screwed through the conduit wall at a location, D, ⅜″ from center of screw hole to cut end of conduit (see  FIG. 8C ). The test results are presented in Table 1. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 EMT Trade Size 
                 Nominal Wall Thickness 
                 Ductile Failure Load 
               
               
                 Designator 
                 (inches) 
                 (lbs.) 
               
               
                   
               
             
             
               
                 ¾″ 
                 0.049 
                 1501 
               
               
                 1″ 
                 0.057 
                 1843 
               
               
                 1¼″ 
                 0.065 
                 2056 
               
               
                 1½″ 
                 0.065 
                 2056 
               
               
                 2″ 
                 0.065 
                 2056 
               
               
                   
               
             
          
         
       
     
         [0106]    Table 1 shows that each of the assemblies failed with loads less than 2,659 lbs., thus ensuring that the conduit hanger assembly will fail before the concrete near the anchor fails. Table 1 also shows that failure load increases with wall thickness, as the 1¼″, 1½″ and 2″ connector pieces all have the same wall thickness and the same load for ductile failure of the connector piece. 
         [0107]    Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments. 
         [0108]    Similarly, it should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention. 
         [0109]    Further, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the scope of the invention.