Patent Publication Number: US-7716887-B2

Title: Shear wall attachment assembly and method of use

Description:
FIELD OF THE INVENTION 
     This invention relates generally to assemblies for attaching a pre-fabricated shear wall to a concrete foundation in non slab-on-grade construction applications. 
     BACKGROUND OF THE INVENTION 
     Pre-fabricated shear walls are commonly used in commercial and residential structures as one method of transferring force, typically shear, a structure into the ground. Consequently, by using a pre-fabricated shear wall, the remaining structure does not have to be designed to carry the shear forces, and as such, lighter or less expensive materials may be used for the remaining structure. Thus, the use of relatively small engineered components to carry specific types of loading, such as pre-fabricated shear walls, helps to reduce the overall cost of the structure. 
     Historically, pre-fabricated shear walls are generally only used with structures that are slab-on-grade applications. This limited application scope prevents the benefits of a pre-fabricated shear walls from being used in applications where the structure is not a slab-on-grade application. A suitable example of one such application is residential housing where flooring structure, such as joists and sheathing, are built upon the concrete foundation The flooring structure simply interferes with standard pre-fabricated shear walls assemblies as they prevent the attachment of the pre-fabricated shear walls to the foundation. Consequently, the pre-fabricated shear wall simply can not transfer the shear load into the foundation. Attempts have been made to build kits that allow a pre-fabricated shear walls to be used in these non slab-on-grade applications, however, they have proved to be either ineffective or overly cumbersome in their use. 
     SUMMARY OF THE INVENTION 
     The present invention is a raised floor assembly that efficiently connects a pre-fabricated shear wall to a foundation in applications other than slab-on-grade. The raised floor assembly includes an engineered wood material block machined to accept a connecting rod there through. The raised floor assembly also includes a connecting rod that is configured to attach at one end to a shear wall and is coupled at the other end to an anchor bolt. Additionally, a transfer plate may be positioned between the pre-fabricated shear wall and the top of the engineered wood material block. A transfer plate may also be provided underneath the engineered wood material block and above the foundation. The transfer plate provides a bearing surface for the pre-fabricated shear wall and also helps maintain connecting rod alignment. Further, the transfer plate transfers the shear loading from the shear wall and connecting rod, into the engineered wood material block, and then back into the connecting rod to be dissipated into an anchor bolt. Additionally, spacers of a variety of arrangements may be provided between the bottom of the engineered wood material block and the foundation. 
     Another aspect of the present invention is a method of using a pre-fabricated shear wall in construction applications other than slab-on-grade. A pre-fabricated shear wall sized to fit on top of flooring or other structure is provided. Also, an engineered wood material block, sized as needed to operate as intended in a space between the bottom of the pre-fabricated shear wall and the foundation, is inserted between the pre-fabricated shear wall and the foundation. Connecting rods are then run from the pre-fabricated shear wall through the engineered wood material block and to anchor bolts in the foundation. Threaded couplers are used to attach the connecting rods to the pre-fabricated shear wall and anchor bolt. A transfer plate may be used as a bearing surface between the pre-fabricated shear wall and the top of the engineered wood material block. Additionally, the transfer plates serve to transfer shear loading into and from the engineered wood material block. Additionally, any variety of spacers may be used between the engineered wood material block and the foundation. Joist hangers and other structure may then be attached to the engineered wood material block if desired. In this manner, the pre-fabricated shear wall is able to transfer shear force to function as intended without being adversely affected by any flooring structure. Additionally, as joist hangers can be attached directly to the engineered wood material block, joist spacing is not interrupted and floor integrity is maintained. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings. 
         FIG. 1  is a partially exploded view of the raised floor assembly according to an aspect of the present invention; 
         FIG. 2  is another exploded view of another aspect of the present invention; 
         FIG. 3  is a plan view of the a portion of the raised floor assembly connected with a concrete foundation in accordance with an aspect of the present invention; 
         FIG. 4  is another sectional view of the assembly of  FIG. 3 , taken along cut line A-A; 
         FIG. 5  is a perspective view of an assembled raised floor assembly in accordance with an aspect of the present invention; 
         FIG. 6  is another perspective view of an assembled raised floor assembly in accordance with an aspect of the present invention; and, 
         FIG. 7  is a plan view of an assembled raised floor assembly in accordance with an aspect of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides a system and method for using a pre-fabricated shear wall in building construction applications that are not slab-on-grade applications. By way of overview, and with reference to  FIG. 1 , an embodiment of the present invention includes a raised floor assembly  20  having a block  32  defining a groove  34  vertically therethrough, a variety of plates and spacers located on top and/or below the block  32  and a connecting rod  28  configured to tie a pre-fabricated shear wall  22  to an anchor bolt  40  of a foundation  42 . Specific details of the raised floor assembly  20  are described with more particularity below. 
     With specific reference to  FIGS. 1-3 , the block  32  is an engineered wood material. Typically, the engineered wood material includes wood strands that are resinated with an appropriate resin material and then formed into a strand orientation controlled mat assembly. Subsequently, the mat assembly is subjected to heat and pressure to cure and form the mat assembly into an engineered wood material of desired proportions. Suitable, non limiting examples of engineered wood material is a laminated strand wood product sold under the TimberStrand® mark and currently manufactured by Weyerhaeuser Company. This material has been produced and sold on the market for several years. As such, those skilled in the art are well aware of TimberStrand® properties and make-up, so a detailed description is not necessary herein to understand the present invention. 
     An embodiment of the present invention includes a block  32  that is configured to interact with at least two anchor bolts  40  in order to attach one pre-fabricated shear wall  22  to the anchor bolts  40  of a concrete wall or foundation  42 . As such, the block  32  is suitably sized to encompass two anchor bolts  40 . Those skilled in the art will appreciate that anchor bolt spacing is largely dependent upon the nature of the building, and its application. Additionally, anchor bolt spacing is also dependent upon local, regional and/or national building code requirements. Further, it is possible that a pre-fabricated shear wall may be sized to attach to more than two anchor bolts. As such, it will be appreciated that if a given design requires a pre-fabricated shear wall  22  that attaches to more than two anchor bolts  40 , then the overall size of the block  32  may be increased to meet this need without exceeding the spirit and scope of this invention. 
     The pre-fabricated shear wall  22  is known in the art. As a result, a detailed description of shear walls is not required to understand the present invention. By way of example only, one suitable, non limiting example of a pre-fabricated shear wall is the TJ®-Shear Panel currently manufactured by Weyerhaeuser Company. However, any other pre-fabricated shear wall is considered within the scope of this invention. 
     With specific reference to  FIGS. 2-4 , grooves  34  are machined into the block  32  to provide a conduit for the connecting rod  28  to extend between the pre-fabricated shear wall  22  and the anchor bolt  40 . One groove is cut for each connecting rod  28 . The overall depth and or width of the grooves  24  is one of design choice, and will be variable based upon necessary design criteria and at least partially dependent upon the relative size (thickness) of the block  32 . It will be appreciated that the overall size of a groove  24  should be sufficient to accept at least a portion of the connecting rod  28  without being overly large such that the size of the groove  34  relative to the size of the block  32  adversely affecting the integrity of the block  32 . In other terms, the relative size (thickness/width) of the block  32  and depth/diameter of groove is determined, at least in part, by a need to properly support and align with a design appropriate pre-fabricated shear wall  22 . 
     As discussed above, the block  32  is constructed of a plurality of resinated strands of wood material formed into an engineered wood product. In an embodiment, the block  32  is machined such that the wood strands are substantially parallel to the main axis of the groove  24 , as best seen in  FIG. 3 . In another embodiment, the wood strands are substantially perpendicular to the main axis of the groove  24  (not shown). 
     The connecting rod  28  is typically a structurally sufficient rod that is threaded at least at both ends. However, it will be appreciated that the rod may be threaded the entire length if the application requires or such is otherwise desired. The rod may be a solid rod or it may be a hollow tube provided the tube provides adequate strength and other physical properties. The connecting rod  28  is attachable to the pre-fabricated shear wall  22  by threading into a hex nut  26 , or other similar threaded connector within or otherwise attached to the pre-fabricated shear wall birdcage  24 . The opposite end of the connecting rod  28  is attached to the anchor bolt  40  via a coupling nut  36 . 
     Assisting in both maintaining the integrity of the block  32  and keeping proper connecting rod alignment is transfer plate  30 . The transfer plate  30  is typically made from any suitable metallic material, such as, without limitation, steel, aluminum, or alloys thereof. In terms of shape, the transfer plate  30  generally sized to cover at least of mating surfaces of the pre-fabricated shear wall  22  and the block  32 . Holes are defined through the transfer plate  30  such that their position corresponds to desired connecting rod spacing. 
     A second transfer plate  30  may also be use on an opposite surface of the block  32 . This second transfer plate  30  may include slotted holes to allow easier insertion as best depicted in  FIG. 2 . The transfer plates  30  serve to transfer the shear force from the connecting rod  28 , into the block  32 , into the second transfer plate  30  back into the connecting rod  28  and into the anchor bolt  40 . Suitable transfer plates  30  are known in the art, and as such a detailed description is not needed herein. However, it will be appreciated that the transfer plate be of sufficient geometry, thickness, and material property to perform its intended tasks. To this end, either or both transfer plates  30  may include fasteners  44  to help maintain the position of the transfer plate  30  relative to the block  32  and further assist in transferring the shear into or out of the associated element. Suitable, non limiting examples of fasteners  44  include nails and screws. However, other fasteners know in the art may also be used without exceeding the spirit and scope of this invention. For example, a suitable adhesive may be used, either alone or in combination with other fastener types. 
     Spacers  38  may also be used with the present invention. The spacers  38  are typically placed over the anchor bolt  40 , adjacent the concrete wall  42 . 
       FIGS. 5-7  depict an aspect of the present invention in use. As illustrated, the raised floor assembly  20  is shown connecting pre-fabricated shear wall  22  with anchor bolts embedded within concrete wall  42 . The block  32  interrupts the rim board  48  and the sill plate  46 . The top of the block  32  is substantially level with the top surface of sheathing  54 . The block  32  is placed with the grooves  34  facing opposite the joists  50 . In this manner, joist hangers  52  may be attached to the opposite side of the block  32 , thereby permitting joist spacing from being interrupted. 
     While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.