Patent Publication Number: US-6907697-B2

Title: Composite systems and methods for anchoring walls

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Patent Application No. 60/244,301, filed Oct. 31, 2000. 

   BACKGROUND OF THE INVENTION 
   The present invention relates generally to construction systems and methods for use in new and existing structures and, more specifically, to composite systems and methods for anchoring walls to footings, foundations, roofs, and slabs. 
   In new construction and retrofit and repair applications it is often necessary to strengthen or reinforce masonry, concrete, and timber walls such that they are capable of withstanding flexural loads caused by, for example, the wind or seismic activity. It is also often necessary to strengthen or reinforce the positive connection between such walls and footings or slabs, enabling the walls to withstand and transfer shear loads as well. Masonry, concrete, and timber walls are typically strengthened using steel reinforcing members, such as reinforcing bar (“rebar”). For example, rebar may be inserted into the cavities of the concrete masonry units (“CMUs” or “cinder blocks”) of a masonry wall, or in the collar joints of a brick structure. The CMU cores may then be filled with grout. The rebar may extend vertically downward and mate with dowel holes drilled in the footing or it may extend vertically upward and mate with dowel holes drilled in the slab. Although marginally effective, in retrofit and repair applications these systems and methods may require the face shells of the CMUs to be temporarily removed. Thus, such systems and methods may be obtrusive, labor-intensive, and expensive. 
   More desirable systems and methods for strengthening or reinforcing masonry, concrete, and timber walls involve the use of high-strength composite materials. The flexural and shear load capability of a wall may be increased by adhering a thin composite fiber sheet or laminate impregnated with an epoxy resin or polymer to its surface. Typical composite laminates include glass, carbon, or aramid fibers. Such composite materials are 5 to 10 times stronger per unit weight than comparable traditional materials. These systems and methods, however, do little to increase the strength of the connection between a wall and a footing, foundation, floor, roof, or slab because they do not interface the wall with its supporting structure. Thus, what is needed are systems and methods utilizing composites for strengthening and reinforcing the positive connection between reinforced or unreinforced walls and footings or slabs. Further, what is needed are systems and methods that are unobtrusive, relatively simple to implement, and inexpensive. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention provides composite systems and methods for strengthening and reinforcing the positive connection between reinforced or unreinforced walls and footings or slabs. These systems and methods may be utilized in new construction and retrofit and repair applications. 
   In one embodiment, a construction system for anchoring a structural member of a building to a base member of a building includes one or more anchoring devices, each anchoring device having a first portion and a second portion, the first portion of each anchoring device fixedly attached to the structural member and the second portion of each anchoring device fixedly attached to the bas e member. Each anchoring device preferably includes a fiber composite material. 
   In another embodiment, a construction system for anchoring a structural member of a building to a base member of a building includes a structural member comprising one of a reinforced wall and an unreinforced wall; a base member comprising a member selected from the group consisting of a footing, a foundation, a floor, a roof, and a slab; and one or more anchoring devices, each anchoring device having a first portion and a second portion, the first portion of each anchoring device fixedly attached to the structural member and the second portion of each anchoring device fixedly attached to the base member. Each anchoring device preferably includes a fiber composite material. 
   In a further embodiment, a construction method for anchoring a structural member of a building to a base member of a building includes fixedly attaching a first portion of a composite fiber anchor to the structural member and fixedly attaching a second portion of the composite fiber anchor to the base member. Each composite fiber anchor preferably has a sufficient strength to transfer a predetermined load from the structural member to the base member. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front elevation view of a wall anchored to a footing or foundation using the composite wall anchoring system of the present invention; 
       FIG. 2  is a cross-sectional side view of one embodiment of the composite wall anchoring system of the present invention, utilizing an elongated clamping/wedging member; 
       FIG. 3  is a cross-sectional side view of another embodiment of the composite wall anchoring system of the present invention; 
       FIG. 4  is a cross-sectional side view of one embodiment of the composite wall anchoring system of the present invention, as applied to a floor or a slab; 
       FIG. 5  is a cross-sectional side view of another embodiment of the composite wall anchoring system of the present invention, utilizing a wedge-shaped groove and an elongated clamping/wedging member; and 
       FIG. 6  is a cross-sectional side view of a final embodiment of the composite wall anchoring system of the present invention, utilizing a T-shaped member. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A typical load-bearing wall used in residential or commercial construction may be made of a building material, such as a plurality of CMUs/cinder blocks, clay blocks, clay bricks, clay tiles, concrete, prefabricated or modular panels, or it may be framed using wood or the like. Such walls are used to transfer loads from a roof, slab, or beam to a footing or foundation. Referring to  FIG. 1 , a structural member  10 , i.e. a wall, may be subjected to a variety of loads, including lateral loads, transverse loads, axial loads  11 , flexural loads, shear loads  12 , coupling loads (including tension loads  14  and compression loads  16 ), etc. These loads may be caused by, for example, the general structural configuration of a building, gravity, the wind, or seismic activity. Structural members  10  may initially be designed to withstand only limited predetermined loading conditions and in retrofit and repair applications, as well as in new construction, it is often necessary to strengthen or reinforce masonry, concrete, and timber walls such that they are capable of withstanding increased predetermined loading conditions. It may also be necessary to strengthen or reinforce the positive connection between such structural members  10  and a base member  18 , such as a footing, foundation, roof, or slab, enabling the walls to withstand increased loads, such as shear loads  12 , tension loads  14 , and compression loads  16 . As such, the base member  18  provides a support capable of withstanding the given predetermined loading conditions. As discussed above, masonry walls, such as those typically used in commercial structures, are often strengthened or reinforced using rebar. More desirable systems and methods, however, involve the use of high-strength composite materials. The flexural load capability of a structural member  10  may be increased by adhering a thin composite fiber sheet or laminate impregnated with an epoxy resin or polymer to its surface  28 . Typical composite laminates include glass, carbon, or aramid fiber composites. These systems and methods, however, do little to increase the shear load transfer between a structural member  10  and a base member  18 . 
   In one embodiment, the composite wall anchoring system  20  of the present invention includes one or more anchoring devices  22 , each anchoring device  22  including a first portion  24  fixedly attached to a structural member  10  and a second portion  26  fixedly attached to a base member  18 , such as the footing, foundation, roof, or slab of a structure. Each anchoring device  22  preferably includes a composite member, such as a thin, flexible, uncured composite sheet or laminate, or a rigid, preformed plate. Each composite sheet or laminate may be as thin as about 0.023 in., although other thicknesses may be utilized. The fibers of the composite sheet or laminate may be aligned such that the sheet or laminate is able to withstand predetermined loading conditions along or around a given axis of the structural member  10 . Multiple composite layers may be utilized, and the orientation of each layer may be varied. The composite laminate anchors  22  may be attached to the structural member  10  and base member  18  by means of mechanical fasteners or a bonding mechanism/adhesive, such as an epoxy resin or a polymer. The bonding mechanism is preferably a strucutural adhesive of sufficient viscosity to allow it to be used to fill a channel or groove. The composite laminate anchors  22  may be attached to a reinforced or unreinforced structural member  10 . For example, the structural member  10  may be reinforced with rebar or an existing composite sheet or laminate adhered to its surface  28 . Thus, one or more anchoring devices  22  form a composite fiber anchoring system  20  having a sufficient strength to transfer predetermined loads from a structural member  10  to a base member  18 . 
   Each composite laminate anchor  22  may be attached to and cover a portion of the surface  28  of the structural member  10 , vertically and/or horizontally. Alternatively, a single composite laminate anchor  22  may be attached to and cover the entire surface  28  of the structural member  10 , vertically and/or horizontally. For example, as shown in  FIG. 1 , a plurality of composite laminate anchors  22  may be utilized such that the first portion  24  of each extends partially or entirely up the surface  28  of the structural member  10  and the second portion  26  of each is fixedly attached to a surface  30  of the base member  18  or disposed within a groove  32  located in the base member  18 . Alternatively, a single composite laminate anchor  22  may be used such that the first portion  24  of the anchor  22  extends partially or entirely up the surface  28  of the structural member  10  and the second portion  26  of the anchor  22  is fixedly attached to a surface  30  of the base member  18  or disposed within a groove  32  located in the base member  18 . Composite laminate anchors  22  may also be utilized on more than one surface of the structural member  10 . 
   Referring to  FIG. 2 , in one embodiment, the first portion  24  of the composite laminate anchor  22  may be fixedly attached to the structural member  10 , such as by using an adhesive. The second portion  26  of the composite laminate anchor  22  may be disposed and fixedly attached within a groove  32  cut into or integrally formed within the base member  18 . The groove  32  preferably has two substantially parallel vertically-extending side portions  34  and a horizontally-extending bottom portion  36 . The groove  32  may be, for example, about 0.50 in. to about 1.50 in. wide and about 2.00 in. to about 5.00 in. deep and, more preferably, about 0.75 in. to about 1 in. wide and about 3.50 in. to about 4.00 in. deep. It should be noted, however, that a groove  32  with other dimensions may be utilized. The groove  32  may also have a predetermined longitudinal or lateral measurement. The groove  32  may be formed using, for example, a saw or an angle grinder with a diamond blade. Preferably, the groove  32  is formed such that it is adjacent to and in line with the surface  28  of the structural member  10 . The second portion  26  of the composite laminate anchor  22  may be disposed within the groove  32  and contacted with an adhesive such that it is fixedly attached to the two vertically-extending side portions  34  and the horizontally-extending bottom portion  36 . The adhesive may further fill the spaced-apart region between the side portions  34 . Optionally, an elongated member  38 , such as a predetermined length of rebar, a cured composite rod, or the like, may be disposed within the groove  32 . The elongated member  38  is preferably made of a material that is compatible with the material comprising the composite laminate anchor  22 , minimizing corrosion, maximizing adhesion, etc. The elongated member  38  is sized to provide a clamping or wedging force, securing the second portion  26  of the composite laminate anchor  22  within the groove  32 . The groove  32  may be filled with a filling compound  33 , such as grout or the like, and made flush with the surface  30  of the base member  18 . It should be noted that this and all embodiments may be used to anchor structural members to roofs and slabs, as well as footings, foundations, and floors. 
   The first portion  24  and second portion  26  of each composite laminate anchor  22 , and especially the second portion  26  in contact with the base member  18 , are sized such that each anchoring device  22  is able to withstand all of a predetermined portion of the predetermined load associated with a given structural member  10  or structure. 
   Referring to  FIG. 3 , in a related embodiment, the first portion  24  of the composite laminate anchor  22  may be fixedly attached to the structural member  10  using a bonding mechanism/adhesive. The second portion  26  of the composite laminate anchor  22  may be disposed within a groove  32  cut into or integrally formed within the base member  18 . The second portion  26  of the composite laminate anchor  22  may be contacted or impregnated with an adhesive and disposed within the groove  32  such that it is fixedly attached to the vertically-extending side portion  40  directly adjacent to the structural member  10 . Optionally, a mechanical fastener  42 , such as a bolt or a pin, may be inserted through a washer member  41 , a securing member  43 , the second portion  26  of the composite laminate anchor  22 , and the base member  18 , securing the second portion  26  of the composite laminate anchor  22  within the groove  32 . The securing member  43  may be, for example, a non-ferrous plate when a carbon composite laminate anchor  22  is used. The groove  32  may be filled with a filling compound  33 , such as grout or the like, and made flush with the surface  30  of the base member  18 . 
   Referring to  FIG. 4 , in an embodiment typically involving a floor or a slab  44 , the first portion  24  of the composite laminate anchor  22  may be fixedly attached to the structural member  10  using a bonding mechanism/adhesive. The second portion  26  of the composite laminate anchor  22  may be disposed within a channel  46  cut into or integrally formed within the slab  44 . The second portion  26  of the composite laminate anchor  22  may be contacted or impregnated with an adhesive and disposed within the channel  46  such that it is fixedly attached to a vertically-extending side portion  48  of the channel  46  directly adjacent to the structural member  10 . Optionally, a third, horizontally-extending portion  50  of the composite laminate anchor  22  may be fixedly attached to the lower surface  51  of the slab  44 . The channel  46  may be filled with a filling compound  33 , such as grout or the like, and made flush with the upper surface  52  and the lower surface  51  of the slab  44 . 
   Referring to  FIG. 5 , in another embodiment, the groove  32  cut into or integrally formed within the base member  18  may have two vertically-extending side portions  34  and a horizontally-extending bottom portion  36  that form a wedge shape having a predetermined lateral measurement. The second portion  26  of the composite laminate anchor  22  may be contacted or impregnated with a bonding mechanism/adhesive and disposed within the groove  32  such that it is fixedly attached to the vertically-extending side portion  40  directly adjacent to the structural member  10 . Optionally, an elongated member  38 , such as a predetermined length of rebar, a cured composite rod, or the like, may be disposed within the wedge-shaped groove  32 . The elongated member  38  provides a clamping or wedging force, securing the second portion  26  of the composite laminate anchor  22  within the groove  32 . The groove  32  may be filled with a filling compound  33 , such as grout or the like, and made flush with the surface  30  of the base member  18 . 
   In a similar embodiment, the groove  32  cut into or integrally formed within the base member  18  may have three substantially parallel vertically-extending side portions, a horizontally-extending bottom portion, and a horizontally-extending top portion which form a partially enclosed channel. The second portion  26  of the composite laminate anchor  22  may be shaped or formed such that it has a hook portion on its end, the hook portion suitable for engaging the partially enclosed channel. The second portion  26  of the composite laminate anchor  22  may be contacted or impregnated with a bonding mechanism/adhesive and disposed within the groove  32  such that it is fixedly attached to the two vertically-extending side portions and the horizontally-extending bottom portion. The groove  32  may be filled with a filling compound  33 , such as grout or the like, and made flush with the surface  30  of the base member  18 . 
   Referring to  FIG. 6 , in a further embodiment, the composite laminate anchor  22  may include a T-shaped member  66  which is partially disposed within a groove  68  cut into or integrally formed within the structural member  10  directly adjacent to the base member  18 . The T-shaped member  66  is preferably made of a rigid, preformed composite material and may be, for example, a fiber-reinforced polymer (FRP) pultruded T-shape. Both the T-shaped member  66  and the groove  68  may have a predetermined lateral measurement. The T-shaped member  66  may be fixedly attached or bonded to the surface  30  of the base member  18  or floor using an adhesive. The T-shaped member  66  may also be fixedly attached to the structural member  10  using an adhesive. A composite sheet or laminate  70  may be fixedly attached to the structural member  10  and the T-shaped member  66  using an adhesive. This embodiment is advantageous because the groove  68  may be cut or formed into the bottom mortar joint  72  of the structural member  10 , maximizing simplicity and minimizing expense. The groove  68  may also increase the composite laminate anchor&#39;s uplift and shear load capacity by utilizing the weight of the structure. 
   In each of the above embodiments, all surfaces to which a composite laminate anchor  22  is attached, including the surface of a structural member, a footing, a foundation, a floor, a roof, or a slab, are preferably cleaned and primed prior to the application of an epoxy resin or polymer adhesive. After a composite laminate anchor  22  is fixedly attached to a surface, a groove, or a channel, the composite laminate anchor  22  may be trimmed as necessary. 
   It is apparent that there have been provided, in accordance with the present invention, systems and methods for anchoring reinforced and unreinforced walls to footings, foundations, floors, roofs, and slabs using composite materials. The present invention permits masonry (including concrete masonry unit (CMU), concrete brick, clay brick, clay block, and clay tile), concrete, and timber walls, and the positive connection between such walls and other structural members, to be reinforced or strengthened such that they are capable of withstanding predetermined flexural loads, shear loads, axial loads, lateral loads, and coupling loads (including tension loads and compression loads). While the present invention has been particularly shown and described in conjunction with preferred embodiments thereof, it will be appreciated that variations in and modifications to the present invention may be effected by persons of ordinary skill in the art without departing from the spirit or scope of the present invention. For example, the type of composite material, the number and orientation of fiber layers, the thickness of the composite material, the dimensions of the first and second anchor portions, and the type of affixing mechanism may all vary depending upon the given materials involved, the environmental conditions, and the predetermined loading conditions. Further, it is to be understood that the principles related to composite fiber systems and methods for anchoring reinforced and unreinforced walls described herein apply in a similar manner, where applicable, to all preferred embodiments.