A preassembled holdown post includes a holdown mounted within a milled recess near a base of the post. The holdown may be secured with screw fasteners inserted at an upward 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.

BACKGROUND

Field of the Technology

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.

Description of the Related Art

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.

SUMMARY OF THE TECHNOLOGY

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.

DETAILED DESCRIPTION

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).

FIGS.1and2are perspective and enlarged sectional views, respectively, of a preassembled holdown post100according to embodiments of the present technology.FIG.3shows an exploded perspective view of a preassembled holdown post100according to embodiments of the present technology.FIGS.4and5show front and side views, respectively, of a preassembled holdown post100according to embodiments of the present technology. The holdown post100is comprised of a post102and a holdown104embedded within a recess106milled or otherwise formed into a face102aof post102. The holdown104may be affixed within recess106by screw fasteners110as explained below.

Post102may be formed of a variety of materials, including for example natural and engineered lumbers. When formed of natural wood, post102may 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, post102may 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 post102may 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 post102may vary in further embodiments.

Recess106may be formed in face102aalong the length of post102, for example near a base (bottom) of post102. In embodiments, the recess106may have a bottom portion106apositioned between 4 and 12 inches from the base of post102, such as for example 6 inches from the base of post102. However, it is understood that recess106may be located anywhere along the length of post102in further embodiments. In embodiments, the recess106may be formed using a milling or routing tool, but it is understood that the recess106may be formed using a variety of other tools in further embodiments.

The shape and length of recess106may vary in embodiments depending on the type of holdown104used. In particular, in embodiments, the shape and size of recess106may match the shape and size of holdown104. While this provides advantages as to the effective transfer of forces from the holdown104to post102, it is understood that the shape and/or size of recess106need not match the shape and/or length of holdown104in further embodiments. As explained hereinafter, holdown104includes a bracket with a hole for receiving an anchor bolt. In embodiments, the recess106is formed to a depth within face102aof post102so that, upon mounting of the holdown104within the recess106, the bracket hole of holdown104may be centered within the post102. That is, the bracket hole may be concentric about a central vertical axis of the post102. It is understood that the recess106may be formed to a depth such that a center of the bracket hole of holdown104is in front of or behind the central vertical axis of the post102in further embodiments.

Preassembled holdown post100further includes a channel112extending from bottom106aof recess106to the base of post102. The channel112is configured to receive the anchor bolt extending from the building foundation as explained hereinafter. The channel112may be formed to a depth and diameter such that the anchor bolt may rest within channel112and fit within the bracket hole of holdown104when the post102is positioned over the anchor bolt. Channel112may be formed using a milling, routing or other tool.

FIGS.3,4and5illustrate detail of one example of a holdown104. In the illustrated embodiment, holdown104may be a pre-deflected holdown, such as for example holdown model number HDU2-SDS2.5 Predeflected Holdown from Simpson Strong-Tie Co. Inc. of Pleasanton, CA. This particular holdown has a rounded, or pre-deflected, base which is designed to eliminate deflection under load when in use. Accordingly, recess106similarly may have a rounded base106amatching the radius of the base of the holdown104. It is understood that a wide variety of other holdowns may be used in further embodiments. For example, holdown model number HD3B Bolted Holdown from Simpson Strong-Tie Co. Inc. may be used, which as a flat, planar base. In such embodiments, the recess106may include a flat, planar base106aas well.

In embodiments, the holdown104may 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 holdown104may be smaller at its top portion. After installation within recess106, at least a portion of the holdown104may protrude from recess106at front face102a, such as for example at its bottom portion. In embodiments, the holdown104may 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 holdown104may be formed of aluminum, titanium or alloys thereof.

As shown for example inFIGS.3,4and7, holdown104may include a bearing plate such as a bracket116having a bolt hole118. Bracket116is configured to sit within the bottom portion of holdown104. The bracket116includes a bearing surface and a pair of legs extending downward at an angle from the bearing surface. The bearing surface includes the bolt hole118formed therethrough. As explained below, an anchor bolt is received through the bolt hole118, and a heavy-duty nut then secures the holdown to the anchor bolt by tightening down against the bearing surface. The pair of legs extending down from the bearing surface have rounded ends with radii matching the radius of the bottom portion of holdown104. In one embodiment, the bolt hole118may have a diameter of 1 5/16 inches, though the diameter of bolt hole118may vary in further embodiments.

Prior to arrival at a construction site, the holdown104may be affixed within recess106to form the preassembled holdown post100according to the present technology. The holdown104may include screw holes120configured to receive screw fasteners110as shown for example inFIGS.3,4and5. While a variety of screw fasteners110may be used, in one embodiment, fasteners110may be ¼ inch by 2½ inch SDS screws from Simpson Strong-Tie Co. Inc. In accordance with aspects of the present technology, the screw fasteners110may be inserted through screw holes120and into post102at an upward angle. In embodiments, this angle may range between 30° and 60°, including for example 45°. It is understood that the screw fasteners110may be inserted at other angles in further embodiments. Inserting the screws at this upward angle reduces shear loads on the screws for example during uplift loads on post102. Using the upward angle, portions of the shear load are converted to tensile loads along the length of screw fasteners110.

In embodiments, there may be eight screw fasteners110, but there may be more or less screw fasteners110in further embodiments. The reduction in shear loads on the angled screw fasteners110allows a smaller number of screw fasteners to be used in comparison to screws inserted perpendicular to the surfaces of the holdown104and recess106. 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 hole120may be partially surrounded by an arcuate tab122(FIG.4) which facilitates insertion of the screw fasteners110at the desired angle. Other structures and features may be used to guide the fasteners in at the desired angle. These arcuate tabs or other structure or features may be omitted in further embodiments. While insertion of the screw fasteners110at an angle provides advantages, it is further contemplated that the screw fasteners110be inserted straight into holdown104, i.e., perpendicular to the surface of holdown104, in further embodiments. In still further embodiments, some screw fasteners110may be inserted straight into holdown104, while others of the screw fasteners110are inserted at the upward angles described above.

Once the holdown104is assembled within recess106, the completed preassembled holdown post100may be shipped to a building site for ready use in a construction.FIGS.6-8illustrate mounting of a preassembled holdown post100onto a foundation126of a building.FIG.6is a side cross-sectional view showing an anchor bolt130cast into, and extending from, the concrete foundation126. A first pair of nuts132may be provided on the anchor bolt130in the foundation126to fix the anchor bolt130to the proper height above the foundation. This height may vary depending on the position of the holdown104along post102. A number of additional nuts134and/or washers136may be mounted along the length of anchor bolt130to improve the ability of bolt130and holdown post100to dissipate loads into the foundation126. Other components may be used instead of or in addition to the above components to mount the anchor bolt130in foundation126.

FIG.6also shows a sill plate140mounted on top of the foundation126. Sill plate140may typically be made of wood and may be positioned between the base of the post102and the foundation126, directly on top of the foundation126. The sill plate may have a thickness of between 1.5 inches and 2 inches, though the thickness may be smaller or larger than that in further embodiments.

FIG.7is a perspective view of the preassembled holdown post100at the building site. The holdown post100is positioned over an anchor bolt130, which extends from the foundation126, through sill plate140and up into the holdown104. The preassembled holdown post100is positioned over the anchor bolt130so that the bolt extends up through the channel112and through the bolt hole118in bracket116. In one embodiment, the anchor bolt may be ⅝ inches, though the diameter may be larger or smaller than that in further embodiments, with the provision that the components are sized so that the anchor bolt130fits within the channel112and through the bolt hole118.

Once the preassembled holdown post100is positioned over the anchor bolt as shown inFIG.7, a heavy-duty nut142may be tightened down over the anchor bolt130as shown inFIG.8to affix the preassembled holdown to the anchor bolt. The nut142may be tightened down against bracket116to remove any slack within the preassembled holdown post100. In particular, by tightening the nut142against bracket116, the holdown104pulls down and holds the post102firmly against the sill plate140. As noted above, in embodiments, the anchor bolt130may be centered along the central vertical axis of post102, so that the holdown104creates a compressive force on post102without generating moment forces biasing the post102off of the vertical axis.

While the figures show a bearing plate in the form of a bracket116, it is understood that other structural elements may be used as a bearing plate to secure the holdown104to the anchor bolt130. 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 holdown104. The anchor bolt130may extend through the washer plate, and the heavy-duty nut142may 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 post100of the present technology provides a variety of benefits. First, as the holdown post100arrives at the building site with the holdown104already assembled into the post102, the holdown post100may be quickly and easily affixed to the foundation. Simply position the holdown post100over 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 holdown104into the post102in 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 post100may be used to affix various structures to the foundation126.FIG.9illustrates an example where a pair of preassembled holdown posts100are used as the vertical edges of a shearwall150. In embodiments, the pair of preassembled holdown posts100may be affixed to the foundation126as described above, and thereafter, central panel152may be affixed to the holdown posts100to form the shear wall150. The central panel152may be formed of a variety of materials, including lumber, steel or drywall, and the central panel152may be affixed to the preassembled holdown posts100by any of various fastening methods, including by screw fasteners and adhesives.

A top beam154may also be affixed along a top edge of shearwall150, to the holdown posts100and/or central panel152. In further embodiments, the shearwall150may be shipped preassembled to a building site with the pair of holdown posts100and top beam154preassembled to the central panel152. In either case, once the shearwall is constructed and the preassembled holdown posts100are affixed to the foundation, the shearwall150is effective in distributing lateral and uplift loads to the foundation126. One or more preassembled holdown posts100may be used as a column and/or framing member as part of other structures in further embodiments.

In embodiments described above, the preassembled holdown post100is used to affix a post102to a foundation126of a building. In accordance with further aspects of the present technology, a modified preassembled holdown post may be used in buildings having multiple floors.FIG.10is a perspective view of a preassembled holdown post160for use in such embodiments. This embodiment may include a post162and a pair of holdowns164aand164bfitting within recesses166aand166bnear the top and bottom ends of post162, respectively. Post162may be any of the materials described above for post102. The bottom holdown164aand recess166amay be identical to holdown104and recess106described above. The top holdown164band recess166bmay also be identical to holdown104and recess106described above, but inverted relative to holdown104and recess106. A channel168extends from a top portion of recess166bto a top of the post162.

FIG.11is a side view of the holdown post160used in a multilevel building, andFIG.12is a side view showing enlarged section12-12ofFIG.11. In this embodiment, the bottom holdown164aattaches to the foundation126as described above. At the top of holdown post160, an anchor bolt170is received within the top holdown164band anchored therein by a bracket116and a heavy-duty nut172as described above. The anchor bolt170may extend upward through an opening in the floor joist174, where it is received within a holdown104/164aof a second preassembled holdown post on the floor above. The second preassembled holdown post on the floor above may be a holdown post100(if there are no additional floors above the second floor), or a holdown post160(if there are additional floors above the second floor). The anchor bolt170may be secured within the holdown104/164aon the second floor by a bracket116and a heavy-duty nut178as described above. By tightening the nut172and/or nut178, the preassembled holdown posts on the first and second floors may be securely affixed to each other through the floor joist174.

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 inFIGS.10-12) may be affixed to each other so that lateral loads may be transferred from upper floors to lower floors and eventually to the foundation126.

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.