Patent Application
20110192111
The present invention relates to structural reinforcement in the construction of buildings and in particular to anchoring of shear walls to concrete foundations.
In the construction of buildings it is common practice to structurally anchor walls to post-tensioned foundations and floors. One method of doing so is by means of tie downs. A tie down system typically consists of several threaded steel rods arranged vertically, with the lower end structurally anchored to the foundation and the upper end coupled to a structural member of a wall by means of a load bearing plate and a threaded nut. The threaded rods serve to prevent movement of the wall in adverse conditions such as high winds or earthquakes. As the wall begins to move in response to wind or earthquake loads, the threaded rods are placed in tension and exert a clamping force between the foundation and a wall structural member, preventing or limiting the movement. In addition to tie downs, the footer of the shear wall is commonly coupled to the concrete foundation by means of shear bolts or similar fasteners spaced at regular intervals.
In order to structurally couple threaded rods and other fasteners to the foundation, anchors are usually cast in place during the construction of the foundation. This is typically accomplished by placing a number of anchors into the form before concrete is poured. Most typical anchor bolts protrude above the level of the finished concrete by several inches in order to attach the sill plate after the concrete is cured. This is not desirable since the protruding anchor bolts interfere with, and can be damaged by, finishing equipment.
In common practice, an anchor is installed by tying “J” style anchor bolts to rebar placed in the form, and leaving the straight section of the bolt protruding up above the level of the finished surface of the concrete slab. Concrete is then poured into the form and covers the lower portion of the installed anchors. After finishing and cure, the form is removed and each anchor is left above the deck for attaching the sill plate. However the finishing is made difficult and time consuming by the protruding portion of the anchors.
In a previous improvement by the authors of the present invention, a submerged anchor is created by first attaching a base plate to the bottom of the concrete form, usually by means of common nails or screws. Such a base plate may consist of a rectangular or round metal plate with a threaded nut welded to it. A plurality of such plates are placed into the form at predetermined intervals. Segments of threaded rod are then cut to an appropriate length and threaded into the base plates. A threaded coupler is then installed on each threaded rod segment, positioned at such a height that its top is just below the finished surface of the concrete. A plug is then installed in each threaded coupler to prevent entry of concrete inside the coupler during the pour which covers the-installed anchors. After finishing and cure, the form is removed and the location of each anchor is determined by measurement or other means such as detection equipment. Concrete is then chipped away to uncover the top of the anchor and the previously installed plug is removed so that threaded rod or other fastener may be installed into the now exposed threaded coupler.
With hundreds of anchors needed in a typical installation, the commonly practiced methods are labor intensive and inefficient. The previous improvement by the authors greatly simplifies the finishing of the poured concrete but still requires additional labor to install and subsequently locate and expose the submerged anchors. What is needed is a pre-assembled anchor system, supplied as a kit, which enables quick and efficient installation of the anchors into the concrete form as well as efficient location and access of the installed anchors after the concrete is cured, without interfering with finishing equipment. The Shear Wall Anchor of the present invention answers this need.
A primary objective of the present invention is to provide a complete and ready kit for the rapid and efficient installation of cast-in Shear Wall Anchors. The kit comprises a pre-manufactured base plate, a threaded rod segment of a predetermined length, a threaded coupler and a plug with a flexible marker feature. The threaded rod segment is installed into the base plate and a threaded coupler is installed onto the threaded rod segment. The plug is installed into the threaded coupler and prevents entry of concrete into the coupler during the pour. The plug features a flexible marker feature, intended to protrude above the poured concrete surface to aid in locating the anchor after the concrete is cured, while the rest of the assembled anchor remains below the surface. The flexible nature of the marker feature prevents it from interfering with finishing equipment. The threaded rod segment is of a length predetermined to position the top of the threaded coupler just below the poured concrete surface in a typical installation. A range of on-site adjustment is possible by moving the threaded coupler up or down on the threaded rod segment.
The present invention is described herein with reference to the following drawings:
An embodiment of the present invention is shown in
The base flange 100, further illustrated in
In addition to the injection molding method disclosed herein, many other methods of constructing the base flange 100 shall be apparent to those skilled in the art, including welding or bonding of the nut 110 or similar threaded fastener to a flange 120 made of either metallic or non-metallic material. Embodiments wherein the base flange 100 is a monolithic part are possible without departing from the scope of the present invention, as long as the flange is configured to receive and structurally retain a threaded rod segment 200, provides a load bearing face 150 and is sized sufficiently to provide stability to the Shear Wall Anchor assembly prior to and while the concrete is being poured. One example of such a base flange may be a monolithic cast iron unit which is shaped and sized similar to the base flange illustrated in
The plug 400 features a flexible marker feature 410. It serves two functions within the kit of the present invention. First, it prevents the entry of uncured concrete into the threaded coupler while the concrete is poured and subsequently compacted. A completed installation is further illustrated as a cross-sectional view in
After concrete 600 is cured, the installed Shear Wall Anchor is located with the aid of flexible marker feature 410 and the plug is removed exposing the threaded portion of the threaded coupler 300. A thin layer of concrete may be chipped away or otherwise removed in the process, as is commonly practiced in the art.
By supplying a complete, pre-configured assembly of the Shear Wall Anchor as a kit the present invention facilitates substantial savings in labor, cost and construction time as compared to currently known and practiced methods.
The embodiment disclosed herein is illustrative and not limiting; other embodiments shall be readily apparent to those skilled in the art based upon the disclosures made herein, without departing from the scope of the present invention.
