Patent Publication Number: US-9404277-B2

Title: Apparatus for positioning anchor bolts

Description:
FIELD OF THE DISCLOSURE 
     The present disclosure relates in general to apparatus for positioning anchor bolts in concrete foundations. 
     BACKGROUND 
     It is commonly necessary to cast anchor bolts into concrete structures such as pile caps, equipment bases, and walls, for purposes of anchoring fixtures ranging from structural steel columns and heavy equipment for commercial and industrial buildings and other large structures, to wooden sill plates on residential foundation walls. Anchor bolts may be required to resist a variety of loads, such as uplift forces, out-of-plane lateral loads, and in-plane shear loads. In cases where anchor bolts by themselves would not provide the required load resistance, steel straps or plates or other appurtenances may need to be used in conjunction with the anchor bolts to transfer loads to the concrete structure. 
     Regardless of the specific purpose of the anchor bolts, it is always desirable and often critically important to ensure that the anchor bolts are held securely in position during construction, so that after the concrete has cured, the anchor bolts will be properly positioned and aligned to receive the fixtures they are intended to anchor. This entails positioning the anchor bolts accurately and securely in the formwork such that they are not susceptible to being knocked out of lateral position or angular alignment during placement of concrete in the formwork, and during related operations such as vibration of the freshly-placed concrete. Misplacement or misalignment of anchor bolts can result in the need for costly and time-consuming modifications to the concrete elements in which they have been cast and/or to the fixtures that they are intended to anchor. 
     There are many known methods and means for positioning anchor bolts in formwork. One simple and common method is to use anchor bolt templates made from dimension lumber (e.g., 2×6s, 2×8s, etc.) or plywood. In cases where multiple anchor bolts are required for anchoring a single fixture (such as the base plate for a structural column), the appropriate bolt pattern is marked out on the wooden template, and slightly oversize holes are drilled in the template to receive the anchor bolts. The bolts are then inserted into the holes in the templates, typically along with nuts and washers or other means to set the height that the bolts will project above the finished concrete. The assembly of the wooden template and anchor bolts is temporarily secured to the formwork, and then concrete can be placed in the formwork. In cases where individual anchor bolts are required at intermittent intervals, such as for anchoring a wooden sill plate to the top of a residential foundation wall (for supporting a wood-framed floor structure), the bolts can be positioned in holes in individual wooden templates temporarily secured to the wall forms. 
     These methods are satisfactory if carried out with proper care. Unfortunately, however, that often does not happen, and the result is anchor bolts that have been cast into the concrete in the wrong position in one or both lateral directions, and/or out of angular alignment, due to factors such as inaccurate marking and drilling of bolt-receiving holes in the wooden templates, and inaccurate or insufficiently secure positioning of the templates on the formwork. 
     Various types of anchor bolt positioning devices are commercially available, but they can be expensive or comparatively difficult to use. Accordingly, there is a need for anchor bolt positioning apparatus that is inexpensive and simple to use, while reducing the chances of error with respect to the positions of anchor bolts in finished concrete structures. 
     BRIEF SUMMARY 
     In a first aspect, the present disclosure teaches a bolt-positioning apparatus for holding anchor bolts in desired lateral positions and angular alignments while being cast into a concrete foundation. In one embodiment, the bolt-positioning apparatus comprises three primary components:
         an elongate main body defining a longitudinal slot bounded by elongate side members;   at least one bolt-holding element (alternatively referred to herein as a bolt holder) slidably disposable within the longitudinal slot in the main body and adapted to receive an anchor bolt (typically by providing a hole extending through the bolt holder); and   two abutment elements slidably disposable within the longitudinal slot in the main body.       

     The bolt holders and the abutment elements of this particular embodiment include stop means for setting the vertical positions of these components relative to the main body. In one variant, the stop means comprises a flange extending laterally outward from an upper region of the bolt holder or abutment element (as the case may be), such that the flange will rest on an upper surface of the main body. When the bolt holder is thus positioned in the longitudinal slot in the main body, the lowermost portion of the bolt holder will not project below the main body. However, each abutment element preferably has a lower portion which, for reasons explained below, extends below the main body when the abutment element is disposed within the longitudinal slot with its stop means resting on the main body. 
     To use the bolt-positioning apparatus, the main body is positioned on the formwork for the pile cap or other foundation element into which anchor bolts are to be cast, with the slidable abutment elements positioned outboard of and on opposite sides of the formwork. One or more bolt holders are positioned in the longitudinal slot in the main body, and an anchor bolt is installed in each bolt holder (either before or after the main body is positioned on the formwork). The anchor bolts may be conveniently retained in their respective bolt holders by means of nuts installed on the threaded portions of the bolts extending above the bolt holders (or by any other suitable means). 
     The main body is mounted on the formwork in a desired position in a direction transverse to its longitudinal slot. The main body may then be fixed in this position relative to the formwork by sliding each of the abutment elements up against the formwork and fixing the abutments to the formwork by any suitable means (such as, in preferred embodiments, by nailing or stapling the lower portions of the abutments to the formwork). The flanges (or other stop means) of the abutments can be nailed or stapled to the upper surface of the main body, at a suitable stage of the process, to fix the position of the main body in its longitudinal direction. 
     The bolt holder(s) may be slid within the slot in the main body to reach a desired longitudinal position relative to the formwork. Optionally, the main body may be provided with a printed linear scale to facilitate quick and accurate positioning of the bolt holders in the slot. Once in their desired positions, the bolt holders may be fixed to the main body by nailing or stapling their stop means to the main body. At this stage, the bolt-positioning apparatus is fully assembled and securely mounted on the formwork, which is then ready to receive concrete. 
     The above-described sequencing of the steps in assembling and mounting the bolt-positioning apparatus is by way of example only, and the required steps could be performed in different sequences to achieve desired results. To provide one example, the one or more bolt holders could be installed in and fixed to the main body before the main body is positioned on the formwork. 
     After the concrete wall or other foundation element has been cast and has sufficiently cured, the bolt-positioning apparatus can be removed by removing the nuts on the projecting anchor bolts, removing the nails, staples, or other fastening means used to fix the abutment elements to the formwork, and then lifting the apparatus off of the foundation. 
     The bolt-positioning apparatus may be fabricated or formed from any suitable material, including but not limited to pressed metal, timber, formed plastic, wax-coated cardboard, pressed paper, and/or pressed wood fiber. Depending on the material used, the apparatus may be reusable. Alternatively, the material used may dictate that the apparatus is suitable for one use only, such as when its components are made from cardboard or similar materials—in which case the apparatus could be simply torn off the formwork (or knocked off with a hammer or other suitable tool) after the concrete has cured. 
     Alternative embodiments of the bolt-positioning apparatus described above may have one sliding abutment element and one abutment element integral with or otherwise fixed to the main body. Other embodiments may have two fixed abutment elements, spaced to suit formwork of specific dimensions. 
     In a second aspect, the present disclosure teaches an anchor bolt holder primarily intended for (but limited to) holding an anchor bolt in a desired lateral position and angular alignment while being cast into the top of a concrete foundation wall. In alternative embodiments, this device could be adapted to hold more than one anchor bolt, and such alternative embodiments are intended to come within the scope of this disclosure. However, this device would most commonly be used in conjunction with a single anchor bolt, as illustrated in the related accompanying Figures, for anchoring sill plates to foundation walls. To distinguish this device from components of the bolt-positioning apparatus described previously, it will be alternatively referred to herein as a sill anchor holder. 
     In typical residential construction, a wood-framed main floor structure is constructed on top of concrete foundation walls. A 2×6 or 2×8 wooden sill plate is anchored to the top of each foundation wall, and then a wood joist floor structure is built on and anchored to the sill plates. The connection between the floor joists and the foundation walls, through the sill plates, must safely withstand uplift forces that may act on the superstructure due to wind. As well, lateral loads from external soil pressure (which could be intensified by vertical surcharge loading on adjacent soil surfaces), and in some cases hydrostatic pressure acting on the foundation walls, must be reacted through the floor-to-wall connections to provide lateral support to the foundation walls. Therefore, anchorage of the sill plates to the foundation walls is critical to the strength and safety of the completed structure. 
     Sill plate anchor bolts may be provided in the form of expansion anchors or wedge anchors (e.g., Hilti® bolts) installed after the foundation walls have cured. However, accurate positioning of such anchors can be a problem. More commonly, sill plate anchor bolts are cast into the walls using wooden templates, and as previously noted, this practice can lead to mislocated bolts if not carried out with sufficient care. 
     The sill anchor holder disclosed herein ensures accurate anchor bolt placement relative to the width of the foundation wall, while being simple and quick to install on the formwork for the wall. The device comprises a main body extending between a pair of abutments, which extend below the main body and are spaced apart by a distance corresponding to the outer width of the wall forms. For example, for an 8-inch concrete wall constructed with ½-inch plywood form panels, the face-to-face distance between the abutments would be 9 inches (preferably plus a tolerance to allow for small variations in the width of the formwork assembly). In alternative embodiments, one or both of the abutments could be made adjustable to facilitate mounting the sill anchor holder on wall forms having significant dimensional irregularities. 
     In one embodiment, a suitably-sized hole for receiving an anchor bolt is provided in the main body at a fixed distance relative to the abutments. For example, if it is desired for the anchor bolt to be cast on the centerline of a concrete wall, the anchor bolt hole in the main body would be equidistant from the two abutments (making the device impossible to mount “backwards” on the formwork). However, if it is desired for the anchor bolt to be offset from the wall centerline, the position of the anchor bolt hole in the main body would be adjusted accordingly. In variant embodiments, the main body could be provided with multiple anchor bolt holes, such that the same embodiment of the anchor holder could be used for positioning anchor bolts at different distances from the face of the finished wall. 
     Regardless of the position and number of anchor bolt holes provided in the main body, methods for installing the sill anchor holder on foundation wall formwork would be essentially the same. Since the distance between the abutments of the sill anchor holder corresponds to the width of the wall forms, it is a simple matter to place the anchor holder over the top of the wall forms with the abutments extending downward alongside the outer faces of the form panels, and then after ensuring that it is in the desired position along the length of the wall, to fix the sill anchor holder to the form panels by nailing or stapling the abutments to the form panels (or using any other suitable attachment means, including but not limited to wood screws). When all required sill anchor holders are in place, and anchor bolts have been installed in all of them (either before or after installation of the sill anchor holders on the formwork), placement of concrete in the wall forms can begin. 
     After the concrete wall has cured, the sill anchor holders can be easily removed from the forms by removing the nuts or other means used to retain the anchor bolts in the anchor holders, breaking the connection between the abutments and the form panels, and then lifting the anchor holders off of their respective anchor bolts and off of the forms. In the case of single-use embodiments made from weaker materials such as cardboard, pressed paper, or pressed wood fiber, or cardboard, the sill anchor holders can be simply ripped off of the forms manually, with the aid of hand tools if necessary, without needing at that stage to remove any nuts or other bolt-retaining means that might have been installed in association with the anchor bolts. 
     In a variant of the sill anchor holder that is particularly adapted for providing enhanced resistance to uplift and lateral forces, the main body of the anchor holder is adapted to receive a metal strap anchor, one end of which has a hole whereby the strap anchor can be installed on a corresponding anchor bolt, and the other end of which has fastener holes for receiving nails or screws for connecting the strap anchor to a wood floor structure built on a sill plate secured to a foundation wall by the anchor bolt. Such strap anchors could of course be installed on the anchor bolts after the foundation wall has been cast and cured. However, mounting the strap anchors on the anchor bolts in conjunction with sill anchor holders during the process of casting the wall can provide practical advantages in terms of construction efficiency, because the wall is ready to receive sill plates immediately after the forms are stripped. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments in accordance with the present disclosure will now be described with reference to the accompanying Figures, in which numerical references denote like parts, and in which: 
         FIG. 1  is a perspective view of the primary components of a first embodiment of a bolt-positioning apparatus in accordance with the present disclosure. 
         FIG. 2  is a cutaway perspective view of the bolt-positioning apparatus of  FIG. 1  mounted on formwork for a concrete foundation element, with anchor bolts installed in the bolt holders of the apparatus. 
         FIG. 3  is a non-cutaway perspective view of the assembly in  FIG. 2 . 
         FIG. 4  illustrates a first embodiment of a sill anchor holder in accordance with the present disclosure, along with an anchor bolt and a strap anchor usable in conjunction with the sill anchor holder. 
         FIG. 5  is a perspective view of a sill anchor holder as in  FIG. 4 , carrying an anchor bolt and a strap anchor. 
         FIG. 6  is a perspective view of formwork for a foundation wall, with sill anchor holders carrying anchor bolts and strap anchors as in  FIG. 5  mounted thereon. 
         FIG. 7  is a perspective view of the assembly in  FIG. 6  after the concrete foundation wall has been cast. 
         FIG. 8  is a perspective view of the assembly in  FIG. 7  after removal of the sill anchor holders from the formwork. 
         FIG. 9  is a perspective view of the foundation wall in  FIG. 8  after removal of the formwork, and with a sill plate being installed on the sill plate anchor bolts. 
         FIG. 10  is a perspective view as in  FIG. 9  after installation of a wood joist floor structure on the sill plate, with the strap anchors bent up and fastened to an exterior header joist. 
     
    
    
     DETAILED DESCRIPTION 
     Bolt-Positioning Apparatus with Sliding Bolt Holders 
       FIGS. 1-3  illustrate a bolt-positioning apparatus  100  particularly adapted for positioning multiple anchor bolts in the formwork for a concrete structure, such as a cluster of anchor bolts in a pile cap or pilaster for receiving the base plate of a structural building column.  FIG. 1  illustrates the main components of one embodiment of apparatus  100 , as follows:
         an elongate main body  10  having a longitudinal slot  15  (which for strength purposes may optionally be subdivided into two or more sections by one or more spacer elements  12 );   one or more bolt-holding elements (alternatively referred to herein as “bolt holders”)  20 , each having:
           a lower section  24 ;   bolt holder fastening means, for facilitating fastening of bolt holder  20  to main body  10 , which bolt holder fastening means may be provided, by way of non-limiting example, in the form of a tab or flange element  22  projecting laterally from an upper region of lower section  24 ; and   a typically vertical bolt-receiving hole  25  extending through lower section  24  of each bolt holder  20 , and with bolt holder  20  being slidably disposable within slot  15  of main body  10 ; and   
           two abutment elements  30 , each comprising:
           a middle section  38 , configured to be slidably disposable within slot  15  of main body  10 ;   abutment fastening means, for facilitating fastening of abutment  30  to main body  10 , which abutment fastening means may be provided, by way of non-limiting example, in the form of a tab or flange element  32  projecting laterally from an upper region of middle section  38 ; and   a lower section  36  extending downward from middle section  38 , and optionally having one or more lateral projections  34  (for preventing vertical displacement of abutment  30  relative to main body  10  after being installed in slot  15 ).   
               

       FIGS. 2 and 3  illustrate a pair of bolt-positioning apparatus  100  mounted on a formwork assembly  50 , with anchor bolts  40  positioned in bolt holders  20 .  FIG. 3  shows the apparatus  100  after bolt holders  20  (and bolts  40 ) have been laterally positioned as desired relative to the fully-assembled formwork  50 , with lower sections  36  of abutments  30  positioned against formwork  50 , and with flange  22  of each bolt holder  20  and flange  32  of each abutment  30  fastened to the associated main body  10 , and with lower section  36  of each abutment fastened to formwork  50  (all by means of suitable fasteners representatively indicated by reference character F in  FIG. 3 ). 
     Slot  15  of main body  10  is shown in  FIGS. 1-3  as having a uniform transverse width, closely corresponding to the width of lower section  24  of bolt holder  20  and middle section  38  of abutment  30 . However, this is by way of non-limiting example only. In variant embodiments, slot  15  optionally may include a section of increased width, such as for example in the case where abutment  30  includes lateral projections  34 , to facilitate insertion of abutment  30  into slot  15 . This may be particularly advantageous in cases where abutment  30  is made of metal or some other comparatively rigid material. 
     In cases where abutment  30  is made of a softer material, such as cardboard or pressed paper, however, abutment  30  can be configured with a longitudinal dimension allowing it to be inserted sideways into slot  15  and then twisted 90 degrees to its final position, as any distortion of abutment  30  that might occur during this procedure would not affect its essential functionality. In such cases, it would not be necessary for slot  15  to have a section of increased width for purposes of installing abutment  30 . 
     Lower section  24  of bolt holder  20  is shown in  FIGS. 1-3  as being of constant rectilinear cross-section, but this is by way of example only. In variant embodiments, lower section  24  could optionally incorporate one or more lateral projections that are slidable within receiving grooves or channels formed in main body  10 , so as to retain bolt holder  20  in main body  10 . In such variant embodiments, it would be advantageous for slot  15  to have a section of increased width to facilitate installation of bolt holder  20 . 
     Sill Anchor Holder 
       FIGS. 4-10  illustrate an embodiment of a bolt-positioning apparatus particularly adapted for positioning anchor bolts in the formwork for a concrete wall, such as for the purpose of anchoring a wooden sill plate to the top of the wall. Bolt-positioning apparatus of this type will be referred to herein as sill anchor holders. 
       FIG. 4  illustrates a sill anchor assembly  200 , including a sill anchor holder  70  (alternatively referred to as the main body of the sill anchor holder) having:
         a pair of spaced sidewalls  72 ;   a first endwall  74 A and a second endwall  74 B extending between sidewalls  72  at opposite ends of sill anchor holder  70 ;   a first abutment  76 A and a second abutment  76 B extending downward, respectively, from first and second endwalls  74 A and  74 B;   optionally, a floor plate  78  bounded by sidewalls  72  (and, optionally, by one or both of endwalls  74 A and  74 B); and   a bolt-holding element  80  position between sidewalls  72 , with a typically vertical bolt hole  85  extending through bolt-holding element  80  and in a selected linear location relative to endwalls  74 A and  74 B.       

     As shown in  FIG. 4 , sill anchor assembly  200  may optionally include an elongate strap anchor  90  having a first end  92 , a second end  94 , a bolt hole  95  proximal to first end  92 , and one or more fastener holes  96  proximal to second end  94 . Strap anchor  90  is shown as being of rectilinear configuration, but this is by way of non-limiting example only. In variant embodiments, strap anchor  90  could be of other shapes while still coming within the scope of the present disclosure. For example, second end  94  of strap anchor  90  could be flared (or “whale-tailed”) to facilitate provision of additional fastener holes  96 . 
     In embodiments of sill anchor holder  70  intended for use with a strap anchor  90 , second endwall  74 B may be provided with a transversely-oriented slot  75  and bolt-holding element  80  similarly may be provided with a transversely-oriented slot  82 , as shown in  FIG. 4 .  FIG. 5  illustrates sill anchor assembly  200  with first end  92  of strap anchor  90  inserted into slot  75  in second endwall  74 B and then into slot  82  in bolt-holding element  80  such that bolt hole  95  in strap anchor  90  is aligned with bolt hole  85  in bolt-holding element  80 , and such that an anchor bolt  40  inserted through bolt holes  85  and  95  will retain strap anchor  90  within sill anchor holder  70 . 
       FIG. 6  illustrates a section of formwork  60  for a concrete wall, with a number of sill anchor assemblies  200  mounted thereon, at desired intervals along the length of the wall. In the illustrated embodiment, the distance between abutments  76 A and  76 B of sill anchor holders  70  has been set to match the width of formwork  60 , such that when sill anchor holders  70  are positioned on formwork  60 , abutments  76 A and  76 B will be closely adjacent to or in contact with the exterior surfaces of the corresponding formwork panels. After all sill anchor assemblies  200  are in their desired positions on formwork  60 , they may be fixed to formwork  60  by means of nails, staples, or other suitable fasteners F connecting abutments  76 A and  76 B to the formwork panels, as seen in  FIG. 7 . The completed formwork/anchor bolt assembly is then ready to receive concrete to create concrete wall  65  as shown in  FIG. 7 . 
     After concrete wall  65  has cured, all sill anchor holders  70  may be removed from formwork  60 , leaving anchor bolts  40  projecting from the top of wall  65  and, when strap anchors  90  are being used in conjunction with anchor bolts  40 , with strap anchors  90  projecting laterally from wall  65  (typically toward the exterior of wall  65 ). This is illustrated in  FIG. 8 . 
       FIG. 9  illustrates concrete wall  65  after formwork  60  has been stripped, with strap anchors  90  projecting outward from the exterior surface  67  of wall  65 , and with a pre-drilled wooden sill plate  120  mounted over anchor bolts  40  (and over first ends  92  of strap anchors  90 ). 
     In  FIG. 10 , a wood joist floor structure has been constructed, with the ends of wood joists  120  bearing on sill plate  110 , and with a header joist  115  running transversely along the ends of joists  120  and the outer edge of sill plate  110 , such that the outer face of header joist  115  is in approximately the same plane as exterior surface  67  of wall  65 . The projecting portions of strap anchors  90  have been bent upward against header joist  115  (with reference character  90 ′ denoting the upwardly-bent sections of strap anchors  90 ), so that nails, screws, or other suitable fasteners can be installed through fastener holes  96  in bent-up sections  90 ′ and into header joist  115 , thus anchoring the floor structure against both lateral displacement and uplift relative to wall  65 . 
     In the illustrated embodiment, abutments  76 A and  76 B are at a fixed spacing, to suit wall formwork assemblies having a constant outside dimension. As noted previously, however, in alternative embodiments of sill anchor holder  70 , one or both of the abutments could be made movable relative to main body  10 , such that the distance between the first and second abutments is adjustable, to facilitate mounting the sill anchor holder on wall forms having significant dimensional irregularities. 
     Also as previously noted, variant embodiments of sill anchor holder  70  may have multiple anchor bolt holes, such that the same embodiment of sill anchor holder could be used for positioning anchor bolts at different distances from the face of the finished wall. As well, other variants of sill anchor holder  70  may have a bolt-holding element that is slidable within a slot (in the same general manner as bolt holder  20  is slidable within slot  15  of main body  10  of bolt-positioning apparatus  100 ), or otherwise movable relative to main body  10 , such that it possible to position an anchor bolt at any of a variety of different locations within sill anchor holder  70 . 
     It will be readily appreciated by those skilled in the art that various modifications to embodiments in accordance with the present disclosure may be devised without departing from the present teachings, including modifications which may use materials later conceived or developed. It is to be especially understood that the scope of the claims appended hereto should not be limited by any particular embodiments described or illustrated herein, but should be given the broadest interpretation consistent with the disclosure as a whole. It is also to be understood that the substitution of a variant of a claimed element or feature, without any substantial resultant change in functionality, will not constitute a departure from the scope of the disclosure or the claims. 
     In this patent document, any form of the word “comprise” is intended to be understood in a non-limiting sense, meaning that any item following such word is included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one such element is present, unless the context clearly requires that there be one and only one such element. Any use of any form of any term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements in question, but may also extend to indirect interaction between the elements such as through secondary or intermediary structure. 
     Relational terms such as but not limited to “vertical” are not intended to denote or require absolute mathematical or geometrical precision. Accordingly, such terms are to be understood as denoting or requiring substantial precision only (e.g., “substantially vertical” or “generally vertical”) unless the context clearly requires otherwise. Any use of any form of the term “typical” is to be interpreted in the sense of being representative of common usage or practice, and not as implying essentiality or invariability.