Patent Document

BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to concrete construction, and more particularly to methods and apparatus for setting reinforcement elements such as rebar for reinforced concrete. 
         [0002]    Reinforced concrete is a well-known construction material which comprises concrete having a reinforcing material such as steel bars or rods embedded therein. This type of reinforcement is referred to generally as “rebar”. Reinforced concrete has beneficial structural properties of both concrete and the reinforcing material. 
         [0003]    Reinforced concrete is often used to form the floor and walls of in-ground swimming pools and similar structures. Typically, the rebar is positioned in place in an excavated pit, and then covered with a sprayable concrete material, for example shotcrete or gunite. 
         [0004]    One problem with this type of construction is that the sections of the rebar must be set on a level plane, but a convenient level reference is not usually available. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    This problem is addressed by a fixture and a method for setting rebar prior to applying concrete. 
         [0006]    According to one aspect of the technology described herein, a fixture for setting rebar at a predetermined distance from the rim of an excavated pit includes: elongated first and second legs each having a proximal end and a distal end, the first and second legs rigidly joined at their mutual proximal ends to form an L-shape; an angle adjustment device carried by the first leg, comprising a foot movable towards or away from the first leg along an axis generally parallel to the second leg; a support bracket carried by the first leg at a predetermined offset distance from the proximal end thereof; and a hook extending from the distal end of the second leg, generally parallel to the first leg. 
         [0007]    According to another aspect of the technology described herein, a method for setting rebar at a predetermined distance from the rim of an excavated pit includes: placing a plurality of fixtures at spaced-apart locations around the rim of a pit excavated into the earth, the pit defined by a recessed floor bounded by a generally vertical perimeter wall and being surrounded by a rim, and wherein an upstanding form is disposed around the perimeter of the rim laterally offset from the perimeter wall, each fixture including: elongated first and second legs each having a proximal end and a distal end, the first and second legs rigidly joined at their mutual proximal ends to form an L-shape; an angle adjustment device carried by the first leg, comprising a foot movable towards or away from the first leg along an axis generally parallel to the second leg; a support bracket joined to the first leg at a predetermined offset distance from the proximal end thereof; and a hook extending from the distal end of the second leg, generally parallel to the first leg; positioning the hook of each of the fixtures in engagement with the form; adjusting each of the fixtures using the angle adjustment device so that the first leg is plumb; and placing a length of rebar into the pit, engaged with the support brackets of the plurality of fixtures, such that the rebar is positioned at a substantially uniform vertical offset distance from the rim. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
           [0009]      FIG. 1  is a perspective view of a swimming pool under construction; 
           [0010]      FIG. 2  is another perspective view of the swimming pool of  FIG. 1 ; 
           [0011]      FIG. 3  is a schematic side view of a fixture for setting reinforcing bar; 
           [0012]      FIG. 4  is a schematic side view of an alternative setting fixture; and 
           [0013]      FIG. 5  is a perspective view showing the fixture in use. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views,  FIG. 1  illustrates an exemplary pit  10  excavated into the earth  12  in order to construct a swimming pool or similar structure. The pit  10  has a perimeter wall  14  extending downward from the ground surface  18 , and a floor  19 . 
         [0015]    A form  16  is placed on the ground surface  18  surrounding all or a portion of the pit  10 . In the illustrated example, the form  16  comprises a thin flexible sheet material such as FORMICA secured in place with stakes  20 . The form  16  is typically offset laterally from the perimeter wall  14  by a specified dimension, for example about 30 cm (12 inches). 
         [0016]    As seen in  FIG. 2 , prior to applying concrete, a reinforcing structure  22  is placed into the pit  10  adjacent the perimeter wall  14 . Typically, the reinforcing structure  22  comprises a plurality of lengths of rebar. The rebar is configured in a grid pattern of horizontal rails  24  and uprights  26  which are tied to each other at their intersections using wire ties or other similar conventional structure. 
         [0017]    It will be understood that it is desirable for the rails  24  to be placed in a true level orientation relative to the Earth, i.e. each complete rail lies in a single horizontal plane. It will be further understood that the floor  19  of the pit  10  will likely not be completely level, either intentionally or unintentionally. Accordingly, it is generally necessary to use the form  16  as a level reference for the uppermost rail  24  (the top of the form  16  would typically be set level to the Earth during installation). More specifically, multiple measurements are taken along the length of the rail  24  to ensure that the rail  24  is a constant vertical distance from the form everywhere around its perimeter. 
         [0018]    Unfortunately, making these measurements is complicated by the fact that the form is offset from the perimeter wall  14 . This means that a single measuring instrument cannot easily be used to obtain an accurate measurement. 
         [0019]    Additionally, even if all measurements are correct, the rail  24  must be held in the proper position until the complete reinforcing structure  22  is complete. In the prior art, this generally entails the use of pins or rods driven into the perimeter wall  14  of the pit  10 . For various reasons, these cannot be left in place and thus require additional labor to remove before the concrete can be applied. 
         [0020]      FIG. 3  illustrates a tool or fixture  28  which may be used to set the rebar while avoiding the above-noted problems. The fixture is generally L-shaped and includes a first or vertical leg  30  and a second or horizontal leg  32  which meet at mutual proximal ends  34 ,  36 . A hook  38  extends downward from the distal end  40  of the second leg  32 . 
         [0021]    An angle adjustment device  44  is disposed at or near the distal end  42  of the first leg  30 . In the illustrated example, the angle adjustment device  44  comprises a first threaded element  46  (such as a nut) affixed to or integral with the first leg  30 , and a second threaded element  48  (such as a threaded rod or bolt) which engages the first threaded element  46 . The second threaded element  48  includes a foot  50  (such as a flat plate) at one end, and a head  51  at the opposite end configured to be engaged by a wrench or other similar tool. For example, the head  51  may have a hexagonal shape. 
         [0022]    Rotation of the second threaded element  48  in one direction moves the foot  50  towards the first leg  30 , and rotation of the second threaded element  48  and the opposite direction moves the foot  50  away from the first leg  30 . 
         [0023]    For the purposes of the present invention, any mechanism which provides a foot that can move inward and outward relative to the first leg  30  (or in other words along an axis generally parallel to the second leg  32 ) may be used in place of the two threaded elements described above. 
         [0024]    A support bracket  52  is affixed to or integral with the first leg  30  and is located a predetermined vertical offset distance “V” from the second leg  32 . In the illustrated example, the support bracket  52  comprises a short section of L-shaped stock defining an upward-facing hook. If desired, multiple support brackets  52  may be provided at preselected distances along the first leg  30 , as shown. 
         [0025]    Optionally, the support bracket  52  or brackets may be made movable or adjustable. For example, the first leg  30  could be provided with a plurality of spaced-apart holes, and the support bracket  52  could be attached using a fastener passing through a selected one of the holes. Alternatively, the vertical leg could be attached to the first leg  30  using a sliding connection. 
         [0026]    Optionally, the fixture  28  may be provided with means for measuring its inclination, such as a known type of mechanical or electronic level. For example, in  FIG. 3  a conventional bubble level  33  is shown attached to the second leg  32 . 
         [0027]    The fixture  28  and its constituent components may be constructed from any suitable material that will maintain its rigidity and dimensional stability in use. Nonlimiting examples of suitable materials include wood, plastics, composite materials, and metals. In the illustrated example, the fixture  28  is fabricated from sections of steel tubing and steel angle stock welded together. 
         [0028]      FIG. 4  illustrates an alternative fixture  128  which is generally similar in construction to the fixture  28  described above. Elements of the fixture  128  not explicitly described may be considered to be identical to those of the fixture  28  described above. 
         [0029]    The fixture  128  includes a vertical leg  130  and a horizontal leg  132  which meet at mutual proximal ends  134 ,  136 . A hook  138  extends downward from a distal end  140  of the horizontal leg  132 . An angle adjustment device  144  is disposed at or near a distal end  142  of the vertical leg  130 . At least one support bracket  152  is affixed to or integral with the vertical leg  130  and is located a predetermined vertical offset distance “V” from the horizontal leg  132 . 
         [0030]    The fixture  128  further includes a clamping mechanism  154 . In illustrated example, the clamping mechanism  154  comprises a first threaded element  156  affixed to or integral with the vertical leg  130 , near the proximal end  134  of the vertical leg  130 , and a second threaded element  158  which engages the first threaded element  156 . The second threaded element  158  includes a jaw  160  at one end (for example a flat plate), and a head  162  at the opposite end configured to be engaged by a wrench or other similar tool. For example, the head  162  may have a hexagonal shape. Rotation of the second threaded element in one direction moves the jaw  160  towards the hook  138 , and rotation of the second threaded element  158  in the opposite direction moves the jaw  160  away from the hook  138 . 
         [0031]    The use of the fixture  28  will now be described with reference to  FIG. 5 . Initially, a pit  10  is formed as described above, and the form  16  is installed. Next, the fixture  28  is set into place adjacent the perimeter wall  14  with the hook  38  abutting the form  16 . This sets the first leg  30  at a fixed, predetermined lateral distance “L” ( FIG. 3 ) away from the form  16 . The hook  38  is then secured to the form  16  to prevent the fixture  28  from moving. In the example shown in  FIG. 5 , the hook  38  is secured by using a conventional C-clamp  39 . Alternatively, using the fixture  128 , the built-in clamping mechanism  154  would be used to secure the hook  138  to the form  16 . As another alternative, any conventional clamping or fastening means may be used. For example, a mechanical fastener such as a screw or bolt could be driven through the hook  38  and the form  16 . 
         [0032]    Once the fixture  28  is secured, it is adjusted to ensure that the first leg  30  is in fact vertical or “plumb” to the Earth. This may be done by using a conventional bubble level (not shown) placed abutting the second leg  32  or the first leg  30 , or by using the built-in inclination measuring means, if present. The foot  50  bears against the perimeter wall  14 . Therefore, using the angle adjusting device  44  to move the foot  50  towards or away from the first leg  30  will cause the fixture  28  to pivot. 
         [0033]    Once the fixture  28  is set with the first leg  30  plumb to the earth, the support bracket  52  will be positioned at a specific lateral distance L from the form  16 , and a specific vertical distance V as described above. The same procedure is repeated using a plurality of identical fixtures  28  around the entire perimeter of the pit  10 . 
         [0034]    Once all the fixtures  28  are set, a length of rebar may then be set into each of the support brackets  52 , thus forming a rail  24  which is substantially in a single plane at a fixed distance below the ground surface  18 . This result is obtained without the need for any measuring. The process may be continued by placing additional rails below the first rail  24 . Because the first rail  24  lies in a single plane, it is possible to set the next rail  24  by using simple offset measurements from the first rail  24 . Alternatively, if the fixture  28  incorporates multiple support brackets  52  as described above, then the additional rails  24  may be formed by placing additional lengths of rebar into the additional support brackets  52 . The uprights  26  described above may then be set in place and connected to the rails  24 . 
         [0035]    Once the support structure is in place, it is a self-supporting and the fixtures  28  are no longer required. Accordingly, the fixtures  28  may be removed prior to the application of concrete. Fixtures  28  may be reused indefinitely. 
         [0036]    The apparatus and method described herein has numerous benefits compared to the prior art. A primary benefit is a large reduction in the time required to set the reinforcing structure. Another benefit is the ease of removal of the fixtures after use. 
         [0037]    The foregoing has described apparatus and methods for supporting a reinforcing structure. All of the features disclosed in this specification, and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. 
         [0038]    Each feature disclosed in this specification may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. 
         [0039]    The invention is not restricted to the details of the foregoing embodiment(s). The invention extends, or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Technology Category: e