Abstract:
An apparatus and method for the seismic stabilization of loads supported by hanger rods are presented. The apparatus includes a compression member that is placed in parallel to a hanger rod and which spans, or substantially spans, the distance from the load, which may be a conduit, and the supporting structure. This apparatus may be retrofit onto existing load-bearing hanger rods, or may be included at the time of installation of the conduit. Methods of installation are described that allow for providing additional structural integrity without disassembly of existing supports.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 62/025,169, filed Jul. 16, 2014, the contents of which are hereby incorporated by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Field of the Invention 
         [0003]    The present invention relates to an apparatus and method of building construction, and more particularly to an apparatus and method for the seismic stabilization of loads supported by hanger rods. 
         [0004]    Discussion of the Background 
         [0005]    One common technique of providing services such as plumbing or electrical wiring into the interior of buildings is by way of conduits that hang from structural elements of the building. Thus, for example, electrical conduits, plumbing pipes, sprinkler pipes, mechanical piping systems, and the like, are typically supported at regular intervals by brackets (“hangers”) that are attached to building structural elements using threaded rods. 
         [0006]    Thus, for example, hangers supported by hanger rods that are typically located throughout a building in the space above the ceiling at spaced-apart locations for supporting conduit that carries a service element and its gravity tension load. In the installation process, the conduit is installed through the hangers, which together form a conduit gravity support assembly. 
         [0007]    A prior art hanger system  10  for supporting a conduit  12  from the underside of an overhead building structure B is illustrated in  FIGS. 1A, 1B and 1C  as a perspective view, side view, and end view, respectively. Hanger system  10  includes a hanger rod  13  and a hanger  11 . Hanger rod  13  has an upper end  13   a  that, as shown in the Figures, can be attached to or otherwise supported by the underside of an overhead building structure B, and a lower end  13   b  that passes through a hole  15  in hanger  11  and which is held in place by a pair of nuts  17 . 
         [0008]    Typically, hanger  11  is sized with an interior that is larger than conduit C, having a diameter D, such that the conduit can be easily placed and rest within the hanger, with the distance between the underside of an overhead building structure B and conduit C adjustable according to the location of nuts  17  on hanger rod  13 . As illustrated in  FIGS. 1A-1C , there is some space about conduit C that can result in the movement of the conduit in hanger  11 . Thus, for example, space (“slop”)  16  exists between conduit C and an upper member  14  of hanger  11 . In the case of a seismic event, conduit C may move rapidly upwards and be forced against an upper member  14 , with a force on hanger rod  13 , as illustrated in  FIG. 1C . This can result in a large and unpredictable force being transferred as a compressive force into hanger rod  13 , with potential destructive results. To prevent such seismic damage, some building codes now prohibit the use at seismic restraint locations of hangers that include slop. 
         [0009]    Attempts to provide hangers that are less prone to damage from earthquakes, have limited success or are difficult of implement in all configurations. One device for reducing seismic damage is the adding of a compression resistance element in the form of a stiffened element that is coupled to hanger rod  13 . See, for example, co-owned U.S. Pat. No. 7,188,809, which is incorporated herein by reference. This device strengthens the hanger to absorb seismic loads. 
         [0010]    Another way to reduce seismic damage is to put an element within the slop space. Thus, for example, placing a spacer into the slop space prevents impact, but does not strengthen the hanger rod. See, for example, U.S. Pat. No. 5,344,108. Further, the hardware necessary to provide conduit restraint depends on the size and shape of the conduit and hanger, and is not generically useful in all cases. 
         [0011]    There is a need in the art for a device and method for reducing failure of hanger system. Such a device should be inexpensive and useful for a wide range of conduit and hanger sizes. The method should be easy to implement and useful as an add-on to existing hangers. 
       BRIEF SUMMARY OF THE INVENTION 
       [0012]    Embodiments presented herein overcome the disadvantages of prior art by providing a compression member to an assembly for supporting an accepted load from a structure. 
         [0013]    In one embodiment, an assembly is described that eliminates the potential damage resulting from hanger slop and provides compression resistance that does not depend on the hanger rod thereby eliminating the need for hanger rod stiffeners. In addition, the assembly utilizes as its main compression member a length of any one of several sizes of strut, pipe or tube materials that are commonly available in the construction of a building. 
         [0014]    One embodiment provides an apparatus for use with a hanger assembly that supports a load from the underside of an overhead building structure. The hanger assembly includes one or more hangers each including a rod attached to the hanger and to the overhead building structure. The apparatus includes a compression member having length between a first end and a second end, where the first end contacts or is near the accepted load, and where the second end contacts or is near the underside of the overhead building structure. If the accepted load moves towards the overhead building structure, some or all of the resulting compression force in the hanger assembly is transferred to the compression member. 
         [0015]    Another embodiment provides an apparatus that supports a load from the underside of an overhead building structure using one or more hangers. At least one hanger is adapted to accept a portion of the load and is attachable to the underside of an overhead building structure. The apparatus includes: a rod connecting at least one hanger to the overhead building structure, where the length of a rod of the plurality of rods between the accepted load and the underside of the overhead building structure is adjustable; and a compression member having length between a first end and a second end. The length between the accepted load and the underside of the overhead building structure of the rod of the plurality of rods is adjustable to a first rod length, wherein that the first end contacts or is near the accepted load and wherein that the second end contacts or is near the underside of the overhead building structure. Further, if the accepted load moves towards the overhead building structure, some or all of the resulting compression force in the hanger assembly is transferred to the compression member. 
         [0016]    Yet another embodiment provides a method of reinforcing a hanger assembly that accepts and supports a load on the underside of an overhead building structure with a compression member having a length between a first end and a second end. The hanger assembly includes one or more hangers each including a rod attached to the hanger and to the overhead building structure, where the hanger is positioned to accept a portion of the load. The method includes: adjusting the position of the hanger on the rod, such that the distance between the accepted conduit and the underside of the overhead building structure is greater than the length of the compression member; positioning the compression member to be parallel to the rod; and adjusting the position of the hanger on the rod such that the first end contacts or is near the accepted load and the second end of the compression member contacts or is near the underside of the overhead building structure. 
         [0017]    Alternative embodiments may also provide for one or more devices to align the compression member with the rod; a compression member having a cross-sectional shape of a c-channel or a hollow cylinder; and a mechanism to adjust the length of the compression member. 
         [0018]    Embodiments described herein include an assembly that eliminates the potential damage in a hanger system associated with slop, and provides superior vertical compression resistance. This may be accomplished as a retrofit to commonly used hanger rods and hangers 
         [0019]    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 hanger assembly, system, and method 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 SEVERAL VIEWS OF THE DRAWING 
         [0020]      FIG. 1A  is a perspective view of a prior art hanger system; 
           [0021]      FIG. 1B  is a side view of the prior art hanger system of  FIG. 1A ; 
           [0022]      FIG. 1C  is an end view of the prior art hanger system of  FIG. 1A ; 
           [0023]      FIG. 2  is a side view of a first embodiment of a hanger system; 
           [0024]      FIG. 2A  is an exploded perspective view of the hanger system of  FIG. 2 ; 
           [0025]      FIG. 2B  is a side view of the hanger system of  FIG. 2 ; 
           [0026]      FIG. 2C  is a top sectional view  2 C- 2 C of  FIG. 2B ; 
           [0027]      FIGS. 3A-3C  are end views  3 - 3  of  FIG. 2B  illustrating three alternative embodiments of the shape of the compression member where it contacts the conduit; 
           [0028]      FIGS. 4A and 4B  are end views  3 - 3  illustrating additional alternative embodiments for distributing the load over the surface of the conduit without the necessity of shaping the bottom of the compression member; 
           [0029]      FIG. 5A  is a side view and  FIG. 5B  is view  5 B- 3 B of  FIG. 5A  which illustrate an alternative hanger system which includes alternative compression member; 
           [0030]      FIG. 6A  is a side view and  FIG. 6B  is view  6 B- 6 B of  FIG. 6A  which illustrate an alternative hanger system which includes alternative compression member; 
           [0031]      FIG. 7A  is a side view and  FIG. 7B  is view  7 B- 7 B of  FIG. 7A  which illustrate an alternative hanger system which includes alternative compression member; 
           [0032]      FIG. 8  is a side view which illustrates an alternative hanger system without a spacer; and 
           [0033]      FIGS. 9A, 9B, and 9C  are side views of alternative embodiments where the length of the compression member is less than the spacing between the conduit and the underside of an overhead building, where  FIG. 9A  illustrates one end of the compression member contacting the conduit and the other end of the compression member near the underside of an overhead building;  FIG. 9B  illustrates one end of the compression member near the conduit and the other end of the compression member contacting the underside of an overhead building; and  FIG. 9C  illustrates both ends of the compression member near, but not contacting either the conduit or the underside of an overhead building. 
       
    
    
       [0034]    Reference symbols are used in the Figures to indicate certain components, aspects or features shown therein, with reference symbols common to more than one Figure indicating like components, aspects or features shown therein. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    The following description provides embodiments of methods and apparatus that provide for improved compression loading of a hanger assembly. One example of a first embodiment hanger system  20  is shown in  FIGS. 2, 2A, 2B, and 2C , where  FIG. 2A  is an exploded perspective view of the hanger system of  FIG. 2 ,  FIG. 2B  is a side view of the hanger system of  FIG. 2 , and  FIG. 2C  is a top sectional view  2 C- 2 C of  FIG. 2B . Hanger system  20  may be an add-on to hanger system  10 , and thus includes the components of hanger system  10  to support a load C from the underside of an overhead building structure B, and also includes a compression member  22  and an upper attachment  41  and a lower attachment  43 . 
         [0036]    While embodiments are illustrated with hanger assembly  20  supporting a load C having a generally circular cross-section, his shape is not a limitation of an application of the present invention. The load accepted by hanger assembly  20  is also referred to in general herein as a conduit. 
         [0037]    As described subsequently, compression member  22  works in parallel with hanger rod  13  to support conduit C to transfer loads between the conduit and the underside of an overhead building structure B. In the absence of an upwards force on conduit C, as may occur during a seismic event, the weight of hanger  11  and conduit C are supported by hanger rod  13 , which is in tension. In the presence of an upwards force of conduit C, compressive forces in hanger system  20  are transferred to compression member  22 , which also restrains movement of conduit C in hanger  11 . 
         [0038]    As shown in  FIG. 2 , hanger rod  13  is attached to hanger  11 , which can accept conduit C, which is supported at a distance L from the underside of an overhead building structure B. Hanger rod  13  is shown as being affixed, at attachment point  18  to the underside of an overhead building structure B (also referred to herein as the plane of support of the tension load) in any number of ways that are well known in the art and which do not form a part of the invention. Inventive hanger system  20  includes a compression member  22  that is attached to hanger rod  13  and spans the distance L from the underside of an overhead building structure B to conduit C. Compression member  22  is parallel to hanger rod  13 , and is shown as being attached to the hanger rod by upper attachment  41  and lower attachment  43 , 
         [0039]    Details of hanger system  20  are shown, for example, in  FIG. 2A . Compression member  22  is a length L of strut/channel, which may be, for example, UNISTRUT® (Unistrut International Corp., Nevada). Alternatively, compression member  22  may be channel of different geometry, a length of pipe or other material capable of providing the required compression resistance.  FIG. 2A  also shows that upper attachment  41  and lower attachment  43  are of generally similar construction, including a doubly threaded element  42 , an optional spacer  44 , a plate  46 , and a pair of nuts  48 . As shown in  FIGS. 2, 2B, and 2C , attachments  41  and  43  thus align compression member  22  with hanger rod  13 . 
         [0040]    In general, compression member  22  of hanger system  20  spans all, or most all, of the distance between the conduit C and the plane of support, which is the underside of an overhead building structure B. This placement of compression member  22  accomplishes two functions. First, compression member  22  greatly restricts or prevents movement of conduit C in hanger  11 . Second, in the event of an upwards force on conduit C, compression forces are transferred compression member  22 . 
         [0041]    The installation of compression member  22  is facilitated by the threaded hanger rod  13  and nuts  17 , which allows the hanger  11  and any conduit C contained therein to be raised or lowered on the hanger rod  13 . Thus, for example, one method of installing hanger system  20  first locates hanger  11  on the hanger rod  13  so that the distance between the conduit C and the plane of support B is greater than the length, L, of the compression member  22 , thus allowing compression member to be easily placed between the conduit and plane of resistance. Once so placed, upper attachment  41  and lower attachment  43  are used to secure compression member  22  to hanger rod  13 . The attachments  41  and  43  can be of the common type illustrated in  FIGS. 2A-C , and may include an optional spacer  44 , which aligns the compression member  22  vertically and outboard of the hanger  11 . Alternative attachment devices  41  and/or  43  may be used to secure hanger rod  13  and compression member  22 . 
         [0042]    Once compression member  22  is secured in place with attachments  41  and  43 , nuts  17  can be moved along hanger rod  13  to raise hanger  11  to a position where the compression member fits against conduit C. In one embodiment, compression member  22  is tightly wedged between the conduit C and the plane of resistance B. When so installed, compression member  22  provides compression resistance to hanger system  20  in a seismic event, in place of hanger rod  13 . With compression member  22  so situated, there is no need to give seismic compression design consideration and/or to increase the compression resistance of hanger rod  13 , such as by the addition of a rod stiffener mechanism. Compression member  22  so situated also prevents the conduit C from moving within hanger  11 , as occurs within slop space  16  of prior art hanger systems. 
         [0043]    In summary, hanger system  20  (a) eliminates the potential damage and/or non-seismic design conformance from having in hanger  11 ; (b) provides code complying compression resistance; and, (c) eliminates the need for separate rod stiffener elements. 
         [0044]      FIGS. 3A-3C  are end views  3 - 3  of  FIG. 2B  illustrating three alternative embodiments of the shape of the compression member  22  where it contacts or is near the conduit C.  FIG. 3A  shows the compression member  22  with a square cut bottom  31 , in which case only a small part of the bottom is in contact with the conduit C.  FIG. 3B  illustrates an embodiment in which the bottom of the compression member  22  has a V-cut  32 , which places more of its bottom surface in contact with the conduit C and thereby distributing compression forces over a greater area of the conduit.  FIG. 3C  illustrates a bottom cut  33  to match the arc of the conduit and thereby put the entire bottom surface in contact with the conduit. 
         [0045]      FIGS. 4A and 4B  are end views  3 - 3  of  FIG. 2B  illustrating additional alternative embodiments which transfer the load over the surface of the conduit C without the necessity of shaping the bottom of the compression member  22 . In the embodiment of  FIG. 4A , a member  41  has an upper part  41   a  that is sized to fit into the lower portion of compression member  22 , and lower part  41   b  that is larger than the interior of compression member  22  and has an arc shaped bottom surface that matches the curvature of the conduit C.  FIG. 4B  illustrates another embodiment in which a sleeve  42  has an interior space sized to receive a portion of the bottom of compression member  22  and an arc shaped bottom surface that matches the curvature of the conduit C. 
         [0046]    In addition to providing a more secure interface between compression member  22  and conduit C and distributing the load on the conduit, members  41  or  42  can also provide the adjustability previously described in connection with connection nuts  17 , for providing a wedge fit for the compression member  22 . Moreover, the members  41  or  42  can be located at the top of the compression member  22  with or without similar members at the bottom. 
         [0047]    While compression member  22  is illustrated as a single member in  FIG. 2 , the invention includes other embodiments where the compression member is comprised of two or more members. These embodiments are illustrated in  FIGS. 5A, 5B, 6A, 6B, 7A, 7B and 8 , which also illustrate alternatives to attachments  41  and  43  as well as an embodiment where the attachments do not include a spacer. 
         [0048]      FIG. 5A  is a side view and  FIG. 5B  is view  5 B- 3 B of  FIG. 5A  which illustrate an alternative hanger system  20  which includes alternative compression member  52 . The embodiment of  FIGS. 5A and 5B  is generally similar to the embodiment of  FIG. 2 , and may include embodiments as illustrated in any one of  FIG. 3A, 3B, 3C, 4A , or  4 D, except as explicitly stated. 
         [0049]    Compression member  52  is formed from the combination of a strut  51  and a member  42  that is affixed to the strut, at an adjustable position, with bolt  34 . Strut  51  may be, for example a length of the strut forming compression member  22 . The length of compression member  52  may thus be adjusted to span the distance and form a wedge fit between conduit C and the underside of an overhead building structure B, and thus provide the same combined conduit restraint and compression loading as compression member  22 . 
         [0050]      FIG. 6A  is a side view and  FIG. 6B  is view  6 B- 6 B of  FIG. 6A  which illustrate an alternative hanger system  20  which includes alternative compression member  62 . The embodiment of  FIGS. 6A and 6B  is generally similar to the embodiment of  FIG. 2 or 5A and 5B , and may include embodiments as illustrated in any one of  FIG. 3A, 3B, 3C, 4A , or  4 D, except as explicitly stated. 
         [0051]    Compression member  62  is formed from the combination of a pipe  51 , and pair of members  42  each affixed to and end of the pipe, at an adjustable position, with a corresponding bolt  34 . With members  42  at both ends of pipe  51 , the length of compression member  62  may thus be adjusted using either or both of the members to span the distance and form a wedge fit between conduit C and the underside of an overhead building structure B, and thus provide the same combined conduit restraint and compression loading as compression member  22 . The embodiment of  FIGS. 6A and 6B  also includes cable ties which are uses as an upper attachment  63  and a lower attachment  64  to secure spacers  44 . 
         [0052]    Alternatively, compression member  52  or  62  may be adjusted to have a length that is less than the distance between conduit C and the underside of an overhead building structure B, as discussed subsequently with reference to  FIGS. 9A-9C , such that, there is a gap between one or both ends of the compression member and conduit and the underside of an overhead building structure. 
         [0053]      FIG. 7A  is a side view and  FIG. 7B  is view  7 B- 7 B of  FIG. 7A  which illustrate an alternative hanger system  20  which includes alternative compression member  72 . The embodiment of  FIGS. 7A and 7B  is generally similar to the embodiment of  FIG. 2 ,  FIGS. 5A and 5B , or  FIGS. 6A and 6B , and may include embodiments as illustrated in any one of  FIG. 3A, 3B, 3C, 4A , or  4 D, except as explicitly stated. 
         [0054]    The embodiment of  FIGS. 7A and 7B  is generally similar to that of  FIGS. 6A and 6B , except that spacers  44  are not included, and the figures illustrate how members  32  can be disposed to align the compression member  61  outboard of hanger  11  without a spacer. 
         [0055]      FIG. 8  is a side view which illustrates an alternative hanger system  20 . The embodiment of  FIG. 8  is generally similar to the embodiment of  FIGS. 5A and 5B , without the use of a spacer. 
         [0056]    In alternative embodiments, a length, M, of the compression member  92  is less than the distance, L, between conduit C and the underside of an overhead building structure B.  FIGS. 9A, 9B, and 9C  are side views of alternative embodiments, where  FIG. 9A  illustrates an end  93  of the compression member  92  contacting conduit C, and the other end  91  of the compression member near the underside of an overhead building B;  FIG. 9B  illustrates end  93  near the conduit and end  91  contacting the underside of an overhead building; and  FIG. 9C  illustrates both ends  91  and  93  near, but not contacting either the conduit or the underside of an overhead building. Compression member  92  may be, for example and without limitation, similar to one of compression members  22 ,  52 , or  62 , and ends  91  and  93  are two distal ends of the compression member, which may include, for example, members  42 . 
         [0057]    In the embodiments of  FIGS. 9A, 9B, and 9C , there is a total gap (L−M), which is equal to the difference between the length, L, between conduit C and the underside of an overhead building structure B, and the length M of compression member  92 . In various embodiments, the gap (L−M) may be, for example, approximately 1/32 inch, 1/16 inch, 3/32 inch, ⅛ inch, or may be more than ⅛ inch. Importantly, the gap is small enough so that compression member  92  accepts the upwards force from hanger rod  13  before the hanger rod suffers permanent deformation or degradation of structural integrity. Thus, in event of an upward force on hanger system  20 , hanger rod  13  will initially take up the compression load. If the force is sufficient, the hanger rod will deform such that compression member  92  contacts both conduit C and the underside of an overhead building structure B, and thus the compressive load in the hanger rod will be transferred to the compression member. 
         [0058]    For any of the embodiments of  FIG. 2, 5A, 5B, 6A, 6B, 7A, 7B, 8, 9A, 9B , or  9 C, compression member  22 / 52 / 62 / 92  restricts or prevents the conduit C from moving within hanger  11 , thereby minimizing or preventing an impact compression force, as may occur in a seismic event, or any other non-trivial compression force, on hanger rod  13 . For embodiments where compression member  22 / 52 / 62  contacts conduit C and the underside of an overhead building structure B, movement of conduit C in hanger  11  is minimal and compression within hanger rod  13  is transferred nearly instantly to compression member  22 / 52 / 62 . For embodiments where compression member  92  does not contact both conduit C and the underside of an overhead building structure B, movement of conduit C in hanger  11  will be limited by the compression member  92 , as will compression within hanger rod  13 . 
         [0059]    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. 
         [0060]    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. 
         [0061]    Thus, while there has been described what is believed to be the preferred embodiments of the invention, 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.