Patent Application
20250092663
The present technology relates to structures for affixing posts or framed walls to a foundation or floor, and in particular to a holdown preassembled into a post to withstand lateral and uplift loads.
Holdowns were developed to mitigate the potentially devastating effects of natural phenomena such as seismic activity, high winds, floods and snow loads on the structural integrity of buildings. Holdowns are used for example to anchor side posts of a shearwall to the building's foundation. A shearwall generally includes a central panel engineered to dissipate lateral loads from wind, seismic activity and other loads on buildings. The central panel effectively distributes the lateral loads to the side posts, which in turn transfer the loads into the foundation. Without holdowns or other structures to anchor the shearwalls to the foundation, shearwalls would be largely ineffective at dissipating lateral loads.
In general, holdowns are assembled onto framing posts for shearwalls and other structures at the construction site. A post is positioned adjacent to an anchor bolt extending up from the foundation, and then affixed to a face of the framing post. Thereafter, a nut and/or washer plate is affixed over the anchor bolt and tightened against the holdown to secure the holdown to the anchor bolt. These steps are time consuming at the construction site, and require some level of proficiency to install the holdown correctly. Faulty installation of the holdown can jeopardize the integrity of the shearwall or other structures secured by the holdown.
The present technology relates to a preassembled holdown post including a milled recess configured and shaped to receive a holdown. The holdown may be preassembled into the recess using a number of screw fasteners. In embodiments, the screw fasteners may be inserted at an upward angle to reduce shear stresses on the fasteners. This upward installation angle also reduces the number of fasteners that are required.
The milled recess may be formed near a base of the post. A channel is further formed in the post between a base of the milled recess and a base of the post. Upon arrival at a construction site, the preassembled holdown post may be positioned over an anchor bolt extending from the foundation. The anchor bolt extends through the channel, up into the holdown in the milled recess. Thereafter, a nut and/or washer plate may be affixed over the anchor bolt and tightened against the holdown to secure the holdown to the anchor bolt. By preassembling the holdown into the post prior to arrival at a construction site, the present technology improves the efficiency and effectiveness of the construction process. Moreover, installing the holdown recessed within the post, as opposed to on a face of the post, reduces moment forces on the post during seismic and other lateral or compressive loads.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the Background.
The present technology will now be described with reference to the figures, which in embodiments relate to a preassembled holdown post including a holdown mounted within a milled recess near a base of the post. The holdown may be secured with screw fasteners inserted at an angle to relieve shear stresses within the fasteners. Additionally, the holdown may be assembled into the post prior to arrival at a building site. This provides a number of advantages to the building process, including quicker installation times and less opportunity for faulty construction.
It is understood that the present technology may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the technology to those skilled in the art. Indeed, the technology is intended to cover alternatives, modifications and equivalents of these embodiments, which are included within the scope and spirit of the technology as defined by the appended claims. Furthermore, in the following detailed description of the present technology, numerous specific details are set forth in order to provide a thorough understanding of the present technology. However, it will be clear to those of ordinary skill in the art that the present technology may be practiced without such specific details.
The terms “top” and “bottom,” “upper” and “lower” and “vertical” and “horizontal,” and forms thereof, as may be used herein are by way of example and illustrative purposes only, and are not meant to limit the description of the technology inasmuch as the referenced item can be exchanged in position and orientation. Also, as used herein, the terms “substantially” and/or “about” mean that the specified dimension or parameter may be varied within an acceptable manufacturing tolerance for a given application. In one embodiment, the acceptable manufacturing tolerance is ±0.15 mm, or alternatively, ±2.5% of a given dimension.
For purposes of this disclosure, a connection may be a direct connection or an indirect connection (e.g., via one or more other parts). In some cases, when a first element is referred to as being connected, affixed, mounted or coupled to a second element, the first and second elements may be directly connected, affixed, mounted or coupled to each other or indirectly connected, affixed, mounted or coupled to each other. When a first element is referred to as being directly connected, affixed, mounted or coupled to a second element, then there are no intervening elements between the first and second elements (other than possibly an adhesive or melted metal used to connect, affix, mount or couple the first and second elements).
Post 102 may be formed of a variety of materials, including for example natural and engineered lumbers. When formed of natural wood, post 102 may be a wide variety of lumbers including for example Douglas Fir, Southern Yellow Pine, Redwood, Cedar, Oak, Pine, Spruce and Hemlock. These woods may be pressure-treated with chemical preservatives to enhance their longevity, though the chemical treating may be omitted in further embodiments. When formed of engineered lumber, post 102 may be a variety of engineered wood products including for example laminated veneer lumber (LVL), glued laminated timber (Glulam), parallel strand lumber (PSL), steel-reinforced engineered wood, cross-laminated timber (CLT) and laminated strand lumber (LSL). It is understood that post 102 may be formed of other materials in further embodiments. In one embodiment, the post may have a length and width in horizontal cross-section of 4 inches by 4 inches, and a vertical height of 12 feet. Each of the length, width and height of post 102 may vary in further embodiments.
Recess 106 may be formed in face 102a along the length of post 102, for example near a base (bottom) of post 102. In embodiments, the recess 106 may have a bottom portion 106a positioned between 4 and 12 inches from the base of post 102, such as for example 6 inches from the base of post 102. However, it is understood that recess 106 may be located anywhere along the length of post 102 in further embodiments. In embodiments, the recess 106 may be formed using a milling or routing tool, but it is understood that the recess 106 may be formed using a variety of other tools in further embodiments.
The shape and length of recess 106 may vary in embodiments depending on the type of holdown 104 used. In particular, in embodiments, the shape and size of recess 106 may match the shape and size of holdown 104. While this provides advantages as to the effective transfer of forces from the holdown 104 to post 102, it is understood that the shape and/or size of recess 106 need not match the shape and/or length of holdown 104 in further embodiments. As explained hereinafter, holdown 104 includes a bracket with a hole for receiving an anchor bolt. In embodiments, the recess 106 is formed to a depth within face 102a of post 102 so that, upon mounting of the holdown 104 within the recess 106, the bracket hole of holdown 104 may be centered within the post 102. That is, the bracket hole may be concentric about a central vertical axis of the post 102. It is understood that the recess 106 may be formed to a depth such that a center of the bracket hole of holdown 104 is in front of or behind the central vertical axis of the post 102 in further embodiments.
Preassembled holdown post 100 further includes a channel 112 extending from bottom 106a of recess 106 to the base of post 102. The channel 112 is configured to receive the anchor bolt extending from the building foundation as explained hereinafter. The channel 112 may be formed to a depth and diameter such that the anchor bolt may rest within channel 112 and fit within the bracket hole of holdown 104 when the post 102 is positioned over the anchor bolt. Channel 112 may be formed using a milling, routing or other tool.
In embodiments, the holdown 104 may have a height of 10- 15/16 inches, a width of 3 inches and a depth a of 3¼ inches at its bottom portion. It is understood that each of these dimensions may vary in further embodiments. As shown in the figures, the depth of the holdown 104 may be smaller at its top portion. After installation within recess 106, at least a portion of the holdown 104 may protrude from recess 106 at front face 102a, such as for example at its bottom portion. In embodiments, the holdown 104 may be formed of 14-gauge steel, stainless steel or galvanized steel, though it may be formed to other thicknesses and of other materials in further embodiments. In further examples, the holdown 104 may be formed of aluminum, titanium or alloys thereof.
As shown for example in
Prior to arrival at a construction site, the holdown 104 may be affixed within recess 106 to form the preassembled holdown post 100 according to the present technology. The holdown 104 may include screw holes 120 configured to receive screw fasteners 110 as shown for example in
In embodiments, there may be eight screw fasteners 110, but there may be more or less screw fasteners 110 in further embodiments. The reduction in shear loads on the angled screw fasteners 110 allows a smaller number of screw fasteners to be used in comparison to screws inserted perpendicular to the surfaces of the holdown 104 and recess 106. In embodiments, this upward angle allows a 20% to 50% reduction in the number of screw fasteners which are needed, including for example a 30% reduction in the number of screw fasteners which are needed. In embodiments, each screw hole 120 may be partially surrounded by an arcuate tab 122 (
Once the holdown 104 is assembled within recess 106, the completed preassembled holdown post 100 may be shipped to a building site for ready use in a construction.
Once the preassembled holdown post 100 is positioned over the anchor bolt as shown in
While the figures show a bearing plate in the form of a bracket 116, it is understood that other structural elements may be used as a bearing plate to secure the holdown 104 to the anchor bolt 130. In one further example, the bearing plate may be a heavy-duty washer plate resting on horizontal edges (not shown in the illustrated embodiments) at opposed sides of a holdown 104. The anchor bolt 130 may extend through the washer plate, and the heavy-duty nut 142 may then be tightened down over the anchor bolt, against the washer plate, to secure the holdown to the anchor bolt and foundation.
The preassembled holdown post 100 of the present technology provides a variety of benefits. First, as the holdown post 100 arrives at the building site with the holdown 104 already assembled into the post 102, the holdown post 100 may be quickly and easily affixed to the foundation. Simply position the holdown post 100 over an anchor rod and tighten it down with a nut. This provides a significant time and cost savings over conventional solutions, where the holdown is affixed to a post at the building site. Moreover, some level of proficiency is required to affix a conventional holdown both over an anchor bolt and to the vertical framing post, which can result in a faulty connection if not done properly. By contrast, the preassembly of the holdown 104 into the post 102 in the present technology allows for the holdown post to be installed at a building site with little or no particular proficiency or experience with installing holdowns.
In embodiments, the preassembled holdown post 100 may be used to affix various structures to the foundation 126.
A top beam 154 may also be affixed along a top edge of shearwall 150, to the holdown posts 100 and/or central panel 152. In further embodiments, the shearwall 150 may be shipped preassembled to a building site with the pair of holdown posts 100 and top beam 154 preassembled to the central panel 152. In either case, once the shearwall is constructed and the preassembled holdown posts 100 are affixed to the foundation, the shearwall 150 is effective in distributing lateral and uplift loads to the foundation 126. One or more preassembled holdown posts 100 may be used as a column and/or framing member as part of other structures in further embodiments.
In embodiments described above, the preassembled holdown post 100 is used to affix a post 102 to a foundation 126 of a building. In accordance with further aspects of the present technology, a modified preassembled holdown post may be used in buildings having multiple floors.
This scheme for affixing preassembled holdown posts to each other on adjacent floors may be used on multiple levels above the second floor in further embodiments. Although not shown, shearwalls on adjacent floors (each including pairs of holdown posts as shown in
In embodiments described above, the holdown at one or both ends of the post is recessed within the post. As described above, this provides advantages of, for example, minimizing moment forces on the post after assembly. However, in further embodiments, it is contemplated that the recess for receiving the holdown, and channel for receiving the anchor bolt, at one or both ends of the post may be omitted. In such embodiments, the holdown at one or both ends of the post may be affixed to the face of the post with fasteners before transport to the building site as described above. Once at the building site, the anchor bolt may be received within the holdown(s) on the face of the post as described above.
In summary, embodiments of the present technology relate to a holdown post for a building constructed at a building site, comprising: a post comprising a recess, and a holdown embedded within the recess prior to arrival at the building site; and fasteners for securing the holdown within the recess of the post.
In another example, embodiments of the present technology relate to a holdown post for a building constructed at a building site, comprising: a post comprising a recess and a channel, the channel extending from a base of the recess to an end of the post, the channel configured to receive an anchor bolt; a holdown embedded within the recess prior to arrival at the building site, the holdown comprising a bearing plate configured to receive the anchor bolt through a hole in the bearing plate enabling the holdown to be secured to the anchor bolt; and screw fasteners inserted through the holdown and into the post at an angle to secure the holdown within the recess of the post, the angle configured to reduce shear stress on the screw fasteners.
In a further example, embodiments of the present technology relate to a method of assembling a holdown post onto a foundation of a building, comprising the steps of: (a) forming a recess in a post; (b) affixing a holdown within the recess to form the holdown post; (c) transferring assembled holdown post to a building site; (d) mounting the holdown post over an anchor bolt with an end of the anchor bolt received through a hole in a bearing plate of the holdown; and (e) securing a nut over the anchor bolt to secure the holdown to the anchor bolt and to secure the post to the foundation.
The foregoing detailed description of the technology has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the technology to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. The described embodiments were chosen in order to best explain the principles of the technology and its practical application to thereby enable others skilled in the art to best utilize the technology in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the technology be defined by the claims appended hereto.
