Patent Grant
7114695
This invention relates generally to building construction and more particularly to the fabrication of concrete wall panels that are tilted up into place and attached to form the walls of a building.
Tilt-up concrete wall panel construction has been used for years to construct commercial buildings such as warehouses, factories, and the like. In general, such construction entails building a rectangular concrete form, usually on site, placing steel reinforcing bars (rebar) or other reinforcement in the form, filling the form with concrete, and, after the concrete cures, tilting the resulting concrete panel into place to form a wall section. Numerous wall sections generally are fabricated and attached together and to framing members of the building to form complete walls. Utility conduits may be embedded within the wall sections as needed to provide for electricity and plumbing. U.S. Pat. No. 3,394,523 of Sackett, U.S. Pat. No. 4,104,356 of Deutsch et al., U.S. Pat. No. 3,604,174 of Nelson, and U.S. Pat. No. 4,856,244 of Clapp disclose various examples of tilt-up concrete wall panel construction techniques.
While traditional concrete wall panel construction techniques have been somewhat successful in constructing commercial buildings, they nevertheless have been fraught with a variety of inherent problems and shortcomings. Among these are the fact that, in most cases, the forms into which the concrete is poured usually are fabricated from wood or metal on site at a worksite such as, for example, on the ground adjacent to where they are to be tilted up to form a wall. The on-site building of such forms is a tedious and time consuming process and further requires a high level of skill on behalf of workers to assure that the panels are all the correct size and configuration. In addition, where wooden forms are used, the process of disassembling the framing members and discarding them after the concrete cures can be time consuming and wasteful. In most cases, reinforcing stakes, spacers, or blocks must be used to reinforce the sides of the concrete forms so that they do not bow outwardly or otherwise deform under the substantial pressures created by the wet concrete poured into the forms. Installing these reinforcing members is yet another time consuming step in the process.
Another problem with prior art techniques relates to the installation within the concrete forms of the rebar, wire mesh, or other reinforcing members that are to be embedded within the finished wall sections. More particularly, the construction of a matrix of reinforcing members is a time consuming and tedious process. This is particularly true in systems where the walls of the form are made from inwardly open channel shaped steel or formed sheet metal. The reason is that the reinforcing members must be installed in the mid-portion of the form between the inwardly projecting lips of the walls. In order the accomplish this, the framing members must be cut to be longer than the distance between the facing edges of opposed lips and jockeyed into place in the middle of the form before being secured in place within the form.
There exists a need for an improved tilt-up concrete wall form and a method of fabricating concrete wall sections using the form that addresses and solves the above mentioned and other problems of the prior art. The form should be lightweight, strong, and portable so that they can be manufactured to exacting tolerances at a remote location and delivered to a job site on a truck for immediate use. Further, the form should be usable without the need for any on-site form construction and without the need to reinforce the walls of the form against bowing under pressure when concrete is poured into the form. No deconstruction of the form should be required after the concrete cures and no waste that requires disposal should be generated during use of the form. At a remote form fabrication facility, fabrication should be quick and efficient and the installation of a matrix of reinforcing rebar in the mid-portion of the form should be accurate, quick, and efficient. An improved method of fabricating tilt-up concrete wall sections using such an enhanced form also should be included. It is to the provision of such a form and method of construction that the present invention is primarily directed.
Briefly described, the present invention, in a preferred embodiment thereof, comprises an improved form for fabricating tilt-up concrete wall sections and an improved method of fabricating tilt-up concrete wall sections using the form. The form has generally C-shaped or channel-shaped roll formed sheet metal frame members that are welded together at their ends to define the shape of the form, which may be rectangular for many applications but that also may take on other shapes according to application specific requirements. A matrix or mat of crisscrossed rebar is disposed in the form to provide reinforcement when concrete is poured into the form during fabrication of a concrete wall section. Each rebar of the matrix extends between opposed frame members of the form and is cut to be short enough to slip into the mid-portion of the form past the inwardly extending flanges of the C-shaped frame members. A unique bracket is slidably disposed on the ends of at least some of the rebars of the rebar mat and each bracket is spot welded to the corresponding frame member and to its rebar. This configuration establishes structural integrity of the assembly. Brackets may be disposed on the ends of each rebar or just on the ends of selected ones of the rebars as necessary to hold the reinforcing mat in place and to establish the desired structural integrity. The form is fabricated at a remote manufacturing facility as follows. First, the roll formed sheet metal frame members are cut to size and welded together at their ends to define a frame of the appropriate size and shape. The generally channel-shaped frame members are oriented with their open or channeled sides facing inwardly toward the middle of the form. In other words, the flanges on the edges of the frame members face inwardly toward each other and thus may be referred to as inwardly extending flanges. Down turned lips preferably are formed along the edges of the flanges to add strength and rigidity.
The crisscrossed rebar mat is then constructed by arranging individual rebars and welding them together at their intersections. A bracket is slid onto the ends of each rebar until the rebar ends protrude from the base of the bracket. With the mat constructed and brackets installed, the entire rebar mat can be positioned in the form. Since the rebars are cut short as mentioned above, the entire rebar mat slips easily past the inwardly extending flanges of the frame members and into the middle of the form. With the rebar mat properly positioned within the form, the brackets on the ends of the rebars are slid toward the frame members until the base of each bracket rests against the outside panel of the frame member between its inwardly projecting flanges. The base portions of the brackets are configured to extend between the flanges of the frame members, thereby automatically centering the rebar mat in the middle of the form. The bases of the brackets are then spot welded to the frame members and the end of each rebar is spot welded to its respective bracket to complete the form. It will thus be seen that the rebar mat is automatically centered and held in place by the brackets. Further, since the rebar mat is welded together and to the brackets, and the brackets are welded to the frame members, the completed form is strong and rigid and maintained in its proper shape by the installed rebar mat.
Since the forms of the present invention are lightweight and rigid, they may be handled, shipped to a jobsite where they are to be used to fabricate concrete wall sections, and unloaded at the job site without fear of the forms becoming warped or deformed. Once at the jobsite, the forms are laid flat on a casting surface, such as a concrete slab, preferably near the location where concrete wall sections are to be erected. The forms are then filled with concrete from a concrete truck, a pump truck, or other source. Again, since the brackets are welded to the frame members and the rebars of the mat welded to the brackets, the rebar mat ties the framing members together and prevents them from bowing or bulging outwardly under the pressure of the wet concrete. Accordingly, no further reinforcing blocks or other reinforcement is required prior to pouring the concrete into the forms as is common in prior art systems.
When the concrete is cured, the resulting concrete wall sections may be tilted up using a derrick or crane and sling arrangement until they are in their proper positions, whereupon they may be attached together and/or to structural support members of the building to form walls. All of the elements of the form remain with the finished concrete wall sections and become a part of the finished wall. Accordingly, no disassembly of the form is required after the concrete cures and no waste that must be discarded is produced.
Thus, a unique and improved tilt-up concrete wall section form is now provided that is quickly, accurately, and efficiently fabricated at a remote manufacturing facility. The form is rigid and self reinforcing and may be handled and shipped to a job site, where it is simply laid on a casting surface and filled with wet concrete without the need for on-site construction or ancillary reinforcing members to prevent bowing of the form. When the concrete cures to form a wall section, the entire structure, form and all, is tilted up and attached to form a concrete wall without any disassembly or waste. The method of fabricating tilt-up concrete walls using forms of the present invention is efficient and substantially quicker than with prior art tilt-up wall systems. These and other features, objects, and advantages of the form and fabrication method of the invention will become more apparent upon review of the detailed description set forth below when taken in conjunction with the accompanying drawing figures, which are briefly described as follows.
Referring now in more detail to the drawings, in which like reference numerals refer to like parts throughout the several views,
A rebar mat 17 is positioned in the form spanning the frame members and, in the preferred embodiment, is formed from individual rebars 18 crisscrossed with respect to each other and spot welded or otherwise attached together at their intersections 18. This forms a rebar mat that is rigid, strong, and not subject to being racked or deformed under stress. As discussed in more detail below, each rebar is cut short enough so that the rebar mat can be slipped into the mid-portion of the form past the inwardly extending flanges of the frame members. Thus, the rebar mat can be fabricated separately from the frame, whereupon it is simply placed in position within the frame.
A special sliding bracket 21 is mounted on each end of the individual rebars. The brackets 21 are slid onto the ends of the individual rebars before the rebar mat is positioned within the frame. When the mat is in position within the frame, the brackets are slid outwardly until they engage the outside panels of the frame members. As discussed in more detail below, the brackets are configured so that when they are slid out and engage the frame members, they automatically center their respective rebars within the form between the inwardly extending flanges of the frame members. Once in place, the base portions 32 (
In use, forms according to the present invention are fabricated in a manufacturing facility as described and shipped to a jobsite where tilt-up concrete walls are to be made and erected. There, the forms are located and laid flat on a casting surface, such as a concrete slab, preferably near where the concrete wall sections ultimately will be erected. The pre-fabricated forms are then filled with wet cement 26 from a source such as a pump truck or from the chute 27 of a concrete truck. As the concrete fills the forms, it exerts a great deal of outward pressure on the frame members of the form, as is the case regardless of the type of form used. However, since the frame members of the form of this invention are securely tied together by the spot welding of the brackets 21 to the frame members and to their respective rebars, the frame of the form easily withstands the pressure of the concrete without bowing or otherwise deforming. Therefore, no ancillary reinforcing blocks or stakes, common in the prior art, are required. In addition, the rigidity of the form prevents it from racking as the heavy concrete spreads throughout the form. As the concrete is poured into the form, it flows around and encases not only the rebar mat, but also the brackets at the ends of the individual rebars. This forms a solid monolithic structure as the concrete cures and the form becomes an integral part of the finished concrete wall. Once the concrete is cured, the resulting wall sections, form and all, are tilted up into place by a crane and secured to each other and to the building frame in the usual way to form concrete walls of the building.
One rebar 18 of the rebar mat 17 is visible in
The preferred installation of the rebar mat into the form is illustrated by phantom lines and arrows in
The invention has been described in terms of preferred embodiments and methodologies that represent the best mode known to the inventors of carrying out the invention. It will be apparent to those of skill in the art, however, that many variations of the illustrated embodiments may be implemented, all within the scope of the invention. For example, the specific shape and construction of the brackets 21 shown in the drawings is one preferred embodiment because of its light weight and economy of fabrication. Many other bracket configurations may, however, be substituted depending upon the shape of the frame, the application, or other factors and any and all specific bracket shapes should be considered equivalent. The specific channel-shape of the frame members also may be different from that illustrated and discussed above. For instance, frame members with inwardly facing C-shaped channels are illustrated and discussed. However, the frame members can take on any of a variety of shapes and configurations depending upon structural and architectural requirements. For example, the frame members can have outwardly extending flanges rather than inwardly extending flanges, obliquely projecting flanges, or may not have any flanges at all. Thus, the particular configuration of the frame members illustrated in the drawings and discussed herein is not intended to and should not be interpreted as limiting the scope of the invention. The forms themselves, although illustrated only as rectangular forms for clarity of description, may take on a wide variety of shapes depending upon the desired final shape of walls to be made with them. For instance, a wall section that will be on the end of a building may be poured in a form having a triangular upper portion to match the pitch of the building roof. These and other additions, deletions, and modifications to the particular preferred embodiment illustrated and discussed herein might well be made by those of skill in the art without departing from the spirit and scope of the invention as set forth in the claims.
This Application is a continuation of U.S. patent application Ser. No. 10/107,561 filed on Mar. 27, 2002 now U.S. Pat. No. 6,658,810 and entitled “Tilt-Up Concrete Wall Panel Form and Method of Fabricating Same.”
| Number | Name | Date | Kind |
|---|---|---|---|
| 2338246 | Hoge | Jan 1944 | A |
| 3394523 | Sackett, Sr. | Jul 1968 | A |
| 3604174 | Nelson, Jr. | Sep 1971 | A |
| 3609935 | Thomas | Oct 1971 | A |
| 3806080 | Franklin et al. | Apr 1974 | A |
| 4059939 | Elliott | Nov 1977 | A |
| 4104356 | Deutsch et al. | Aug 1978 | A |
| 4159097 | Strickland | Jun 1979 | A |
| 4291858 | NeSmith | Sep 1981 | A |
| 4506428 | Gerhard | Mar 1985 | A |
| 5205942 | Fitzgerald | Apr 1993 | A |
| 5216866 | Ekedal | Jun 1993 | A |
| 5335472 | Phlipps | Aug 1994 | A |
| 5491948 | Harris | Feb 1996 | A |
| 5635097 | Aiello | Jun 1997 | A |
| 6182416 | Brackin | Feb 2001 | B1 |
| 6260329 | Mills | Jul 2001 | B1 |
| 6502362 | Zambelli et al. | Jan 2003 | B1 |
| Number | Date | Country | |
|---|---|---|---|
| 20040118066 A1 | Jun 2004 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10107561 | Mar 2002 | US |
| Child | 10731635 | US |
