1. Field of the Invention
The present invention relates to an apparatus for reducing the risk of damage to buildings as a result of lateral forces applied to the building and, in particular, concerns a pre-assembled internal shear panel that can be installed into a building wall to reduce the risk of the building wall becoming dislodged from the foundation as a result of lateral forces such as those generated in earthquakes and high winds.
2. Description of the Related Art
In typical building construction the walls are comprised of a frame that is anchored to the foundation and a covering that is installed onto the frame. Typically, the frame of a building has a number of vertically extending studs that are positioned between an upper and a lower plate. The lower plate is typically anchored to the foundation and the covering material, e.g., plywood, siding and the like, is then nailed to the studs.
One problem that occurs in buildings is that lateral forces applied in a direction parallel to, and in the plane of, the wall can cause the upper section of the wall to move relative to the lower plate which is anchored to the foundation. These forces often occur as a result of natural phenomenon such as high wins and earthquakes. It will be evident that too much movement of the upper sections of the wall relative to the anchored lower plate can result in damage to the frame of the wall which can further result in the wall collapsing.
To address this particular problem, buildings are often equipped with a lateral bracing system. One type of lateral bracing system is known as shear panels that are installed in the walls to stiffen the structure against racking or deformation in the plane the walls. For example, in the typical residential building, wherein the frames are primarily constructed of wood, plywood sheathing is attached to three or more of the studs, and to the upper and lower plate of the wall, to inhibit the movement of the upper portion of the wall in response to these lateral forces. Specifically, the end studs of the shear panel or posts are typically fastened to a heavier anchor bolt, known as a holdown bolt, at a position adjacent to the end posts by means of various hardware types known as holdowns. The plywood, which forms a vertical diaphragm, is attached to the upper plate and the lower plate of the wall, and also to the posts with specified boundary fasteners such that the shear force is transmitted through the diaphragm to end posts, the holdown device, and bolt. Hence, the tendency of the upper portion of the wall to move relative the lower portion of the wall as a result of the shear forces is reduced. Basically, the plywood diaphragm creates diagonal braces that inhibit movement of the upper portion of the wall relative to the lower portion.
These shear panels are typically built in the field during the construction of the building. It will be appreciated that constructing these structures in the field can be time consuming and can also result in construction errors that will affect the strength of the wall.
Further, these types of shear panels and, in particular, the plywood shear panels used in wooden framed buildings, must be comparatively large to withstand the significant amount of lateral forces that are generated in large earthquakes. For example, most building codes limit the story drift or lateral deformation to ¼″ for an 8′ wall height in all types of buildings. The ratio of the height of various shear panels to their width is also limited by the building code depending on the type of sheathing material used. To achieve this limitation on story drift in response to this applied lateral force, the shear panel must generally include a plywood diaphragm that is on the order of 2 to 4 feet in length. While on long walls there may be the space available between openings to position a 4-foot long or greater shear panel, in smaller buildings with smaller lengths of walls, there is often no room to construct shear panel of this size. Further, it will be appreciated that multiple story buildings are more susceptible to larger lateral forces often necessitating even larger lateral bracing structures. This exacerbates the problem of a limited amount of space in walls of smaller lengths.
Hence, there is a need for a shear panel which is easy to install and is comparatively small in size so that it can be readily installed in walls having shorter lengths. To this end, there is a need for a prefabricated shear panel that is capable of ready installation into and between the studs of walls wherein the shear panel is capable of minimizing the movement of the upper portion of the wall relative to the lower portion to within an acceptable amount.
The aforementioned needs are satisfied by the pre-assembled internal shear panel apparatus of the present invention which is comprised of two side members, or vertical posts that are spaced apart, and at least one diaphragm member that is positioned between, and connected to, the two side members. Further, there is an upper and lower member that is connected to the side members and the diaphragm members so as to form a rigid structure.
The lower member is positioned within a bracket member that is configured to be attached to a holdown bolt that is anchored in the foundation. There are two bracket members, one on each end, which are attached to one of the posts and both of the bracket members are also respectively connected to holdown bolts that are anchored in the foundation of the building.
The side, top and bottom members of the shear panel are all attached to form a preferably rectangular frame of which the upper member of the panel is connected to an upper plate of the wall. This results in a shear panel capable of opposing lateral forces in the plane of the wall so as to reduce movement of the upper plate of the wall with respect to the lower plate.
In one preferred embodiment, the posts are formed out of a plurality of light gauge steel members and there are two sheets of sheet steel forming a diaphragm that are attached to both of the posts substantially along the full length of the posts and to the top and bottom frame members, with one sheet on each side of the frame. Further, there is preferably at least one reinforcing member which interconnects the posts positioned between the upper and lower member and between the two sheets forming the diaphragm members. The reinforcing member stiffens the side members and reduces the tendency for the steel sheets to buckle when the shear panel is under load.
The shear panel of the preferred embodiment is attached at the bottom corners to holdown bolts which are anchored in the foundation of the building and the bottom member of the steel frame is fastened to the concrete foundation with a minimum of two anchor bolts or approved fasteners. The upper member of the shear panel of the preferred embodiment is connected to the upper plate of the frame of the wall so that lateral forces in the plane of the wall are transmitted to the sear panel. Because the later force is applied through the top plate there is an overturning effect on the panel that is resisted by the end posts, holdown assembly and anchor bolts. The horizontal shear force is resisted by the additional anchor bolts or fasteners in the bottom frame members. In one preferred embodiment, a gusset is used to attach the upper member of the shear panel to the upper plate of the frame of the wall. Further, in the preferred embodiment additional shear bolts are mounted through the lower member of the shear panel into the foundation of the building to reduce the likelihood that the shear panel will become dismounted at the bottom end from the foundation as a result of shear forces applied against the wall.
The shear panel of the preferred embodiment is preferably shipped to the job site substantially assembled. The installer simply has to attach the mounting brackets to the holdown bolts that are anchored in the foundation and then position the lower member of the shear panel in the brackets. Subsequently, the installer has to secure the lower member of the shear panel to the brackets, and, hence, to the concrete foundation with cast-in-place anchor bolts or other approved fasteners. Subsequently, the remainder of the shear panel can be attached to the lower member. Further, the upper member of the shear panel can then be attached to an upper portion, e.g., the upper plates, of the wall. Hence, installation of the shear panel of the preferred embodiment is simplified over constructing an appropriate shear panel in the field during the construction of the building.
In addition, the configuration and metal construction of the shear panel of the preferred embodiment results in a shear panel that is capable of withstanding greater amounts of shear forces than the shear panel structures of the prior art. This allows the shear panel of the preferred embodiment to be smaller in size, e.g., have a smaller width, which allows the shear panel to be installed along smaller wall sections without a decrease in the amount of protection against lateral forces. These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompanying drawings.
Reference will now be made to the drawings wherein like numerals refer to like parts throughout.
Referring initially to
The side posts 102a and 102b at their upper ends 103a and 103b respectively, are connected to a horizontal upper member 104. Similarly, the vertical posts 102a and 102b are connected at their respective lower ends 105a and 105b to a horizontal member 106. The interconnection between the posts 102a and 102b and the upper and lower members 104, 106 respectively is described in greater detail hereinbelow in reference to
Further, at least one diaphragm member 110 which forms a brace member for the apparatus 100 extends between the vertical posts 102a and 102b substantially along the entire height of the vertical posts 102a and 102b and is also connected to the upper member 104 and the lower member 106. As will be described in greater detail hereinbelow, the diaphragm member serves to transmit a force in opposition to the force exerted on the upper member 104 to the lower member 106.
As is also shown in
In the preferred embodiment there are two diaphragm members 110a and 110b which are preferably comprised of sheet steel wherein each of the diaphragm members 110a and 110b have a lip 122 formed on a side of the diaphragm member 110. Preferably, as shown in
Hence, the post 102a is comprised of an inner retaining member 114 that is reinforced by the reinforcing members 116 and the tube 126 positioned therein. The diaphragm members 110a and 110b are then positioned adjacent the inner retaining member 114 and captured within the outer retaining member 120.
As shown in
The foregoing description has described the preferred construction of the vertical post 102a, it will be appreciated that the vertical post 102b is constructed in an identical fashion as the vertical post 102a.
As is also shown in
The lower member 106 is also comprised of a piece of U-channel that has an opening 148 that is substantially equal to the thickness of the outer retaining member 120 of the vertical post 102a and 102b to thereby allow the vertical posts 102a and 102b to be positioned within the lower member 106 and secured thereto. In the embodiment shown in
As is also shown in
In one preferred embodiment of the shear panel of the present invention, the reinforcing members 116 are comprised of two pieces of Cee-channel that is 1½″×2″ wide, 18 gauge and approximately 7′-2″ or 9′-6″ in length. The inner retaining member 114 is comprised of 2⅞″×2¼″ U-channel that is 18 gauge and is 7′-8″ or 10′ long depending upon the embodiment of the shear panel that is being fabricated. The diaphragm members 110a and 110b are preferably comprised of a sheet of 18 gauge steel that is 7′-8″ or 10′ long depending upon the application and 2′ wide wherein the sheet is bent along one edge to form a 2″ lip. The outer retaining member 120 is preferably comprised of 18 gauge U-channel that is 3″×2″ in cross-section and is either 7′-8″ long or 10′ long depending upon the application. The upper and bottom members 104 and 106 are comprised of 18 gauge U-track that is 5 13/16″×2⅜″ in cross-section and is 1′-10″ in length. The brackets 130a and 130b are preferably comprised of ⅛″ thick steel that is 6½″ in height, 2 9/16″ in width and 3″ long. Further, along the side walls of the bracket there are three ½″ holes drilled on both of the side walls. Further, there is a 2 9/16″×3″×1/2″ thick plate 150 welded to the bottom of the bracket with a 1″ hole in the center and ⅛″ chamfers along the lower 3″ edges.
The installation and operation of the sheer panel 100 will now be described in reference to
The shear panel 100 is connected to an upper plate 162 of the wall structure, which in this embodiment is comprised of two 2″×4″ boards, via a gusset 164 in the manner shown in
At the lower end of the shear panel 100, the brackets 130a and 130b comprise an anchor point or attachment point that are mounted over two holdown bolts 166a and 166b that are anchored in the foundation 170 of the building. The holdown bolts 166 can either be previously anchored into the foundation 170 or they can be retrofitted into the foundation in the desired location using well-known methods. Generally, the holdown bolts 166 stub up through the upper surface of the foundation 170 and the brackets 130a and 130b can be positioned over the holdown bolts with the bolts extending through an opening 133 (
Subsequently, the lower member 106 can then be installed in the bracket and the vertical posts 102a and 102b can then be positioned within the lower member 106 at a position adjacent the brackets 130a and 130b so that the bolts 132 can be installed through the brackets 130a and 130b, the lower member 106 and the posts 102a and 102b to secure the posts 102a and 102b to the brackets 130a and 130b and thereby anchor the vertical posts 102a and 102b and the diaphragm members 110a and 110b forming the panel 100 to the foundation.
It will also be appreciated that it may be desirable to attach the shear panel 100 to one or more shear bolts 172 that are previously mounted in the foundation 170. The shear bolts 172 stub up out of the foundation 170 and holes can be drilled in the lower member 106 so that the lower member 106 can be positioned over the shear bolts 172 and then attached to the shear bolts via nuts. Further, it will be appreciated that spacers 174 (
From the foregoing description, it will be understood that the shear panel 100 of the preferred embodiment is easy to install in the wall of a building. Specifically, the builder of the wall simply has to ensure that the holdown bolts 106 and the shear bolts 172 are positioned so as to be substantially co-planar with one of the two outer edges of the upper plate 162 of the frame. Subsequently, the brackets 130a and 130b can then be mounted on the holdown bolts in the previously described fashion and the lower member 106 can be connected to the shear bolts and positioned within the brackets 130a and 130b.
Subsequently, the remainder of the shear panel 100 can be installed in the lower member 106 and the bolts 132 can be installed to connect the vertical post 102a and 102b to the lower member 106 and the brackets 130a and 130b. Further, screws 124 along the lower member 106 can then be installed to interconnect the lower member 106 to the diaphragm members 110a and 110b. Once the shear panel 100 is connected to the foundation, the gusset 164 can then be connected to the upper member 104 and the upper plate of the wall. In the preferred embodiment, the shear panel 100 will preferably be shipped to the job site in substantially the configuration shown in
It will be appreciated that installation of the shear panel 100 on the wall 168 reduces the tendency of the upper portion 180 of the wall 168 to move with respect to the foundation 170. Specifically, the arrows 182 and 184 are representative of lateral forces that are directed parallel to the length of the wall 168. It will be appreciated that when a lateral force in the direction of the arrow 182 is applied to the wall 168 the upper portion 180 of the wall 168 will have a tendency to pivot about the left-most holdown bolt 166a. However, the force in the direction of the arrow 182 is opposed by an equal and opposite force exerted on the right bottom corner of the shear panel 100 by the holdown bolt 166b thereby reducing the tendency of the shear panel to overturn. The shear bolts 172 prevent the panel and wall 168 from sliding in the direction of the arrow 182.
Basically, the gusset 164, the upper member 104, the diaphragm members 110a and 110b and the posts 102a and 102b provide a diagonally braced frame in each direction of the arrow 186 in
Hence, the shear panel 100 opposes the movement of the wall in directions which are parallel to the length of the wall and in the plane of the wall and, based upon pseudo-cyclic testing performed at the University of California, Irvine, in Irvine, Calif., a shear panel having the configuration of the preferred embodiment of the shear panel 100 is capable of withstanding up to 3500 lbs. of load applied to the upper portion 180 of a 7′-8″ wall structure 168 while only having the upper portion of the wall deflect approximately ½″ or less from its normal resting position.
Essentially, the shear panel 100 preferably functions like a large vertical cantilevered girder fixed at the bottom and loaded horizontally in the plane of the panel at the top member. The diaphragm members 110a and 110b resist the shear forces and the flanges of the girders are comprised of the post assemblies 102a and 102b which resist the axial stress due to bending. Preferably, the brackets 130a and 130b and the holdown bolts 166 are sized to withstand the uplift force generated by the overturning moment of the panel 100 when exposed to forces in the direction of the arrows 182 and 184, i.e., horizontal forces, and the shear bolts 172 are sized to resist the horizontal shear force. The reinforcing members 140 serve the purpose of reducing the tendency of the diaphragm members 110a and 110b to buckle under the loads generated by the shear forces. It will be appreciated that the shear panel 100 of the preferred embodiment is thus very easy to install and is capable of withstanding significantly more shear forces than the shear panels that are currently used in residential and business construction.
Further, a gusset 164′ can also be used to attach the lower member 106 of the upper shear panel 100 to a floor space member 200 of the two-story wall 190. The straps 194 firmly connect the bottom portion of the upper shear panel 100b to the top portion of the bottom shear panel 100a so that the upper panel 100b is anchored to the lower panel 100a across the floor space member 200 between the two stories of the wall.
Further, the lower gusset 164′ further reduces the tendency of the upper portion of the second story of the wall 190 to move with respect to the lower plate 196 of the second story of the wall as the shear panel is connected along its entire width to the floor space member 200 of the second story of the wall via the lower gusset 162b. Since the lower shear panel 100a is attached to the foundation in the manner described above in reference to
It will be appreciated that the previously described preferred embodiments of the shear panels are easy to install as a result of their prefabrication and provide excellent protection against shear forces that are acting in a direction parallel to the length of the wall. Specifically, the shear panel of the present invention uses two reinforced posts with an interconnecting diaphragm member to transfer the forces, resulting from a shear force being applied against the wall, to the holdown bolts that are embedded in the foundation. Since the panel is largely pre-fabricated, the worker simply has to connect the panel to the upper plate of the wall and then connect the lower portion of the panel to the holdown and shear bolts mounted in the foundation. Hence, it is simpler for the construction worker to install the shear panel and, since the panel is pre-fabricated, the possibility of field installation error, which would increase the probability that the panel would not perform as intended, is of course reduced.
Further, since reinforced posts are used in conjunction with metal diaphragm sheets, the amount of shear force that can be transferred to the holdown bolts is increased. Specifically, using the shear panel constructed in the manner as the shear panels of the preferred embodiment, a shear panel that is only two feet in width can be used in the place of a shear panel structure fabricated out of plywood and the like that is over four feet in length. Hence, shear panels constructed according to the teachings of the preferred embodiment, e.g., with reinforced metal posts and with metal diaphragm members, can be used to provide protection against movement of the upper portions of walls relative to the foundations for walls that are short in length.
Although the preferred embodiment of the present invention has shown, described and pointed out the fundamental novel features of the invention as applied to these embodiments, it will be understood that various omissions, substitutions, and changes in the form of the detail of the device illustrated, may be made by those skilled in the art without departing from the spirit of the present invention. Consequently, the scope of the invention should not be limited to the foregoing discussion, but is to be defined by the appended claims.
This application is a continuation of application Ser. No. 09/603,707, filed on Jun. 23, 2000. Application Ser. No. 09/603,707 is a continuation of application Ser. No. 08/985,479, filed on Dec. 5, 1997, now abandoned. Application Ser. No. 08/985,479 is a continuation of application Ser. No. 08/572,519, filed on Dec. 14, 1995, now U.S. Pat. No. 5,706,126.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 09603707 | Jun 2000 | US |
| Child | 13385333 | US | |
| Parent | 08985479 | Dec 1997 | US |
| Child | 09603707 | US | |
| Parent | 08572519 | Dec 1995 | US |
| Child | 08985479 | US |