Abstract:
A strand chair for supporting a prestressing cable in a cement cast. The strand chair contains a lower cup for receipt of a lower prestressing cable as well as an upper cup for supporting an upper prestressing cable. The strand chair utilized the pressures of the stressed cables to support and position a reveal which runs along the casting bed. Furthermore, the strand chair supports the placement of rebar utilized in the cement casting.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Patent Application No. 62/074,976, filed Nov. 4, 2014, which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to strand chair supports for prestressing cables for a cement plank cast. 
     Description of the Related Art 
     Concrete panels are cast in long lengths on a casting bed. Prestressing or prestressed cables are run along and within the casting bed in order to support the cast concrete panels. The prestressing cables are put under high tension prior to casting, yet tend to droop, sag, or move from an initial position during concrete casting. 
     Plastic clips or chairs are generally used to support the prestressing cables and any rebar that may be run through the casting bed. Current clips or chairs utilized in the industry are cumbersome, time consuming, or expensive to install. Some chairs or clips fail to appropriately support the prestressing cables or rebar due to the weight of the units being supported or the tension being applied to the cables. The further weight and inertia of concrete pouring into the cast tends to move or improperly orient the prestressing cables. 
     After appropriately supporting the prestressing cables and rebar, concrete is poured into the casting bed. After a curing process, the concrete is cut for particular use. 
     SUMMARY OF THE INVENTION 
     In one aspect, the invention relates to a strand chair for supporting prestressed cables comprising an elongated body having a longitudinal axis, a lower portion, and an upper portion. The strand chair further comprises an upper cup in the upper portion sized to receive a first prestressed cable and a lower cup in the lower portion sized to receive a second prestressed cable and has at least two legs at the lower portion. The upper cup is open axially along the longitudinal axis and the lower cup is open normal to the longitudinal axis. 
     In another aspect, a method of supporting prestressed cable in a cement casting having a casting pallet. The method comprises providing a strand chair, having an elongated body with a longitudinal axis, an upper cup sized to receive an upper cable, a lower cup sized to receive a lower cable, at least two legs, and a v-notch between the two legs wherein the upper cup is open axially along the longitudinal axis and the lower cup is open normal to the longitudinal axis. The method further comprises tensioning the upper and lower cables in a cement casting, positioning the strand chair with the upper cable received in the upper cup, and rotating the strand chair until the lower cable is received in the lower cup with the at least two legs resting on the cement casing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a front view of a strand chair in a cured concrete cast. 
         FIG. 2  is a front view of the strand chair of  FIG. 1 . 
         FIG. 3  is a side view of the strand chair of  FIGS. 1 and 2  supporting a prestressing cable and rebar. 
         FIG. 4  is a front perspective view of the strand chair of  FIGS. 1-3  supporting a prestressing cable and rebar. 
         FIG. 5  is a rear perspective view opposite the strand chair of  FIG. 3 . 
         FIG. 6  is a close-up view of a cup of the strand chair. 
         FIG. 7  is a view illustrating a step of a method of installing the strand chair to an upper prestressing cable. 
         FIG. 8  is a view illustrating a step of a method of installing the strand chair to a lower prestressing cable. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As used herein, the term ‘prestressing’ or ‘prestressed’ when used in combination with cable refers to cable which can be or has been tensioned by a force such that the cable becomes taut. It should be appreciated that the terms ‘prestressing’ and ‘prestressed’ can be used interchangeably and should not be understood as limiting the invention to either of a cable which has been tensioned or will be tensioned. It is further contemplated that the invention can be utilized with a non-tensioned cable, which is capable of tensioning. 
     Turning now to the drawings and in particular to  FIG. 1 , a strand chair  10  couples to a set of two prestressed cables  12  and rebar  14 . The strand chair  10  is disposed over a reveal  16  running along a casting pallet  18  at the bottom of a concrete cast  20 . The reveal  16  can run laterally relative to the direction of the prestressing cables  12  and the rebar  14  or can run longitudinally. The concrete cast  20  can comprise one or more voids  22  created in the cement cast  20  during cementing operations. The strand chair  10  uses the high tension of the prestressing cables to hold the reveal  16  in place along the casting pallet  18  during cementing operations. The strand chair  10  is preferably made of high strength polymers or plastics, which are strong enough to support the weight and tension of prestressed cables  12  during cementing operations, while adding minimal weight to the cement cast. Alternatively, the strand chair  10  can be made of other materials, including but not limited to steel, cast iron, aluminum, or any other suitable material. 
       FIG. 2  shows a front view of the strand chair  10  isolated from the cementing environment. The strand chair  10  comprises a body having an upper portion  32  and a lower portion  34  disposed opposite of the upper portion  32 . The body  30  defines a longitudinal axis L along the length of the body  30 . The upper portion  32  comprises an upper cup  36  and the lower portion  34  comprises a lower cup  38 , both cups  36 ,  38  being sized to receive a prestressed cable  12 . The upper cup  36  is open axially along the longitudinal axis L of the body  30 , while the lower cup  38  is open normal to the longitudinal axis L of the body  30 . 
     The upper portion  32  further comprises a matrix structure  40  disposed between the side members  42 . The side members  42  extend beyond the upper cup  36 , defining cup walls  48  preventing lateral movement of a prestressed cable inserted into the upper cup  36 . The matrix structure  40  comprises a plurality of triangular recesses  44  defined between a plurality of angled ribs  46 . It should be appreciated that the triangular recesses defining the matrix structure  40  are exemplary, and that square or circular recesses as defined by the ribs, or any other such geometry can define the matrix structure  40 . Furthermore, the matrix structure  40  can be a latticed structure or otherwise, such that structural support is defined between the side members  42  while optimizing overall weight of the upper portion  32 . 
     A support member  60  defines a junction between the upper portion  32  and the lower portion  34 , and is shaped to define the hollow opening of the lower cup  38 . The support member  60 , opposite of the upper portion  32 , coupled to a set of legs  62 . The legs  62  extend parallel to the longitudinal direction of an inserted prestressed cable  12  and perpendicular to the longitudinal direction of the reveal  14 . Each leg  62  comprises a foot  64  for resting on the casting pallet or other concrete casting surface. The foot  64  can be rubber or plastic to resist sliding movement of the strand chair  10  during cementing operations. A reveal support  66  is disposed between the legs  62 , adjacent to the reveal  16  which is disposed between the legs  62 . 
     The support member  60  can be further shaped to receive and retain the prestressed cable. The lower cup  38  can further comprise a space  70 . The space  70  minimizes overall contact surface with the prestressed cable and can provide a corner  74  to grip the prestressed cable upon insertion. Adjacent the space  70  is a guide  72 . The guide  72  defines a surface for resting and guiding the prestressed cable into the lower cup  38 . The guide  72  can further be shaped to support a stand-alone prestressed cable  12 . The size and shape of the guide  72  can be altered to give more or less support to a stand-alone prestressed cable as may be desired. A rebar cup  76  is disposed in an underside of the guide  72  for supporting rebar adjacent to the strand chair  10 . 
     Turning to  FIG. 3 , a side view of the strand chair  10  best illustrates the width of the portions  32 ,  34  as well as the reveal support  66 , having prestressed cables  12  disposed within the cups  36 ,  38 . The upper portion  32  and lower portion  34  are sized to support the prestressed cables  12  running through the cups  36 ,  38 . The reveal support  66  further comprises a v-notch  80 . The v-notch  80  can comprise a v-shaped groove in the reveal support  66  for resting on the reveal  16 . Alternatively, the v-notch  80  can snap, lock, weld, or otherwise connect to the reveal  16 . The v-notch is adapted to position the strand chair  10  such that the legs  62  and feet  64  are spaced from the reveal  16 , preventing misalignment, tipping, or movement of the strand chair  10  or reveal  16  relative to one another during cementing operations. 
     Turning now to  FIG. 4 , a perspective view illustrates the strand chair  10  having a corner  74  extending above the guide  72 . The extended corner  74  provides for greater gripping of the inserted prestressed cable  12 . Additionally, the guide  72  has an arcuate surface as compared to a flat surface of  FIG. 2 . The arcuate surface provides a curved surface for guiding the prestressed cable  12  into the lower cup  38  during cable insertion. Furthermore, the arcuate guide  72  can curl around the rebar cup  76  for holding the inserted rebar  14  as compared to simply aligning the rebar  14 . 
       FIG. 5  is similar to that of  FIG. 4 , showing the reverse perspective side of the strand chair  10 .  FIG. 5  additionally shows a gap  90  defined between the sides of the legs  62 . An interior wall  92  extends from below the lower cup  38  and couples to the reveal support  66 . Thus, the body  30  is supported by the reveal  16  through the interior wall  92  and is supported by the legs  62  and the feet  64  on the casting pallet or bottom surface. 
       FIG. 6  shows close-up view of the lower cup  38 . The lower cup  38  is surrounded by the support member  60 , and further defined by the space  22  and the guide  72 . The guide  72  has an extension  100  for defining the length of the guide  72  and can further extend downward to at least partially surround the rebar cup  76 . 
     It should be understood that while the embodiment of the strand chair as shown is described as having two legs  62 , the strand chair can comprise at least two legs  62 . For example, the strand chair can have four legs with two legs disposed on either side of the reveal  14 . Furthermore, the strand chair can have four legs comprising two sets of two integral legs on either side of the reveal  14 . It should be appreciated that a four-leg embodiment will increase the stability of the strand chair  10 , such that tensioning of the cables, installation of additional strand chairs, or cementing operations does not subject the installed strand chairs to tipping. 
     Now turning to  FIGS. 7 and 8 , a method of installing the strand chair  10  will be described. Beginning with  FIG. 7 , a strand chair  10  is provided and can be the strand chair  10  of  FIGS. 1-6 , having the upper cup  36  being open axially along the longitudinal axis L of the strand chair  10  and the lower cup  38  open normal to the longitudinal axis L. The cables are tensioned to comprise prestressed cables  12 . The cup walls  48  are positioned adjacent to the upper prestressed cable  12  such that the strand chair  10  can be moved to insert the prestressed cable  12  into the upper cup  36  as shown by arrow  110 . The strand chair  10  is slid until the strand chair is positioned with the upper prestressed cable  12  positioned within and in contact with the upper cup  36 . 
     Turning to  FIG. 8 , the strand chair  10  is rotated about the upper prestressed cable  12  disposed within the upper cup  36  as illustrated by arrows  112 . The strand chair  10  is rotated until the lower prestressed cable  12  is inserted into the lower cup  38 . The feet  64  can rest on the casting pallet  18  and the reveal support  66  can be aligned such that the reveal  14  is position within the v-notch  80  of the reveal support  66 , spacing the legs  62  between the reveal  14 . 
     The reveal  14  can be laid on the casting pallet  18  prior to positioning the strand chair  10  with the upper prestressed cable  12  in the upper cup  36 . The method can further comprise receiving rebar in the rebar cup  76  positioned parallel to the prestressed cables  12 . Furthermore, the method can include repeating the method for multiple strand chairs  10  disposed within a cement casting. 
     It should be appreciated that the strand chair as described herein provides for simplified installation of chair support for a plurality of prestressed cables in a concrete cast. The axially opened orientation of the upper cup and the perpendicular opening of the lower cup further provides an easy method for installing the strand chair with cable being previously tensioned, without the need to attempt to moved, pull, or adjust the prestressed cables prior to installation. Additionally, the strand chair provides the v-notch for positioning the strand chair over a reveal as well as securing the reveal relative to the strand chair and the prestressed cables, minimizing the incidence of movement of the reveal or strand chairs during cementing operations. 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the forgoing disclosure and drawings without departing from the spirit of the invention, which is defined in the appended claims.