Static structures (e.g. – buildings) – Irreversibly reactive component
Reexamination Certificate
1999-08-26
2001-01-23
Lev, Bruce A. (Department: 3634)
Static structures (e.g., buildings)
Irreversibly reactive component
C052S281000, C052S481100
Reexamination Certificate
active
06176053
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a wall track assembly and method for installing the same. More particularly, the present invention is directed to a unique cap track assembly and method for installing the same into a cyclical design fire resistant wall structure.
Conventional fire resistant wall assemblies typically comprise a track assembly, metal studs, and gypsum wallboards, i.e., drywall, all installed between a floor and an overhead structure. The studs are retained in the track assembly by suitable securing means. Vertically oriented studs are typically mounted in a spaced relationship to provide a support structure onto which the gypsum wallboards or other wall surface materials can be installed. The studs often include lateral bores through which electrical, plumbing, or other conduits can also be mounted. The studs and gypsum wallboards are spaced from the overhead structure in order to allow for settling or other movement of the overhead structure with respect to the wall assembly. Typically, a fireproofing material or firesafing material is applied adjacent the track in the space between the gypsum wallboard and the overhead structure.
An important concern among builders, architects, and those in the construction industry is compliance with building codes relating to fire resistant or fire rated wall construction, as well as compliance with building codes relating to seismic movement, such as earthquakes. Building codes typically require fireproof ratings of one hour, two hours, or some other time period for walls and connections between walls and an overhead structure, such as a deck or roof. There are typically two categories of tests for fire rated walls—the static fire test and the cyclical fire test. The static fire test provides test panels with movement in design, but the panels are not cycled before fire testing. However, they are tested in an open position in the fire chamber. With static condition fire rated wall assemblies, when deflection occurs, such as during an earthquake, the studs move vertically upwardly and downwardly within the track and there is a gap between the top of the studs and the overhead structure for the fire caulking or fireproofing material. The problem with static condition fire rated wall assemblies is that when deflection occurs, the fire caulking and gypsum boards can be easily crushed. Many building codes, especially those in earthquake zones, are now requiring that fire rated wall assemblies be of a cyclical condition, that is, that they pass the cyclical fire test. The cyclical fire test requires the test panels to be cycled, and then the same panel fire tested in an open position. The test criteria adopted by the International Conference of Building Officials (ICBO) for the cyclical method is 500 cycles prior to submitting the panel to fire, that is, the gypsum boards or entire wall assembly must move vertically upwardly and downwardly 500 times with approximately a 1 inch deflection.
Building codes, especially in earthquake zones, also require a load test for fire rated walls. Building movement is a factor in substantially vertical connections made between the studs and such conventional structural elements as interior walls, exterior walls, and floor assemblies. Building movement can negatively effect vertical seams between consecutive sheets of gypsum wallboards and can crack firesafing material such as caulking.
Known cyclical condition fire rated wall assemblies include a two track assembly or a one track assembly. The two track assembly utilizes a first track along the overhead structure and a second track within the first track. The one track assembly utilizes a single track along the overhead structure and supersedes the two track assembly because the one track assembly is simpler and less expensive, and unlike the two track assembly, the one track assembly provides positive attachment of the wall assembly to the overhead structure. Thus, one track assemblies have been found to be advantageous and are commonly used.
Known one track assemblies for use with fire resistant and seismic resistant cyclical design wall structures are disclosed in U.S. Pat. No. 5,127,203 and U.S. Pat. No. 5,127,760. These patents both disclose a fire resistant and seismic wall structure having a cyclical design slotted track which allows for both upward and downward movement of the structure without adversely affecting positive attachment of the framing members. As shown in
FIG. 1
(prior art), the known cyclical design slotted track includes a U-shaped track
2
with a plurality of vertical slots
4
along the sides of the track, and the track
2
is attached to a stud
6
. However, there are problems associated with the use of these slotted tracks. For example, such slotted tracks require the installation of shims on the tracks so that any overlapping layers of gypsum wallboards that are installed will be able to move against the shim during deflection in the cyclical condition to maintain the fire rating. For purposes of this application, a “shim” is defined as a piece of metal or other material used to fill out space, for example, for leveling or deflection. After the track assembly and any other wall attachments, such as electrical wiring, plumbing, and the like, are installed, the gypsum wallboards are installed. The installation of the gypsum wallboards with these known track assemblies requires the installation of shims as well. It is difficult to install the shims after the track and other wall attachments have been installed or mounted because of the difficulty in seeing where to install the shims and the difficulty in maneuvering around the other wall mountings to install the shims. This increases the overall time for installing the gypsum wallboards and increases the overall labor and construction costs. In addition, another problem with these known track assemblies is that when the gypsum wallboards are installed, the tops of the gypsum wallboards must be cut into a fluted configuration or another configuration in order for them to fit properly into the overhead structure. Having to specially cut the top of the gypsum wallboard is also difficult, time consuming, and increases the overall labor and construction costs. Finally, another problem with these known track assemblies is that the gypsum wallboards are installed along the outer sides of the track and during deflection move vertically upwardly and downwardly against the outside of the gypsum wallboard on the studs rather than within the track. Problems with this configuration occur because when the gypsum wallboard is installed or deflects vertically upwardly, the gypsum wallboard hits or rubs against any overlapping gypsum wallboard. The attachment means is raised above the surface of the track. Thus, upon deflection, the gypsum wallboard is forced over the raised attachment means and creates unnecessary friction or damage to the gypsum wallboard causing it to deteriorate, resulting in possible loss or failure of fire rating.
Another known cyclical design one track assembly for use with fire resistant and seismic resistant wall structures is disclosed in U.S. Pat. No. 5,471,805. Although this track assembly does not have slots and does not require the use of shims, it does require the use of clips for reinforcing the stud to track connection while allowing for deflection. This known cyclical design track includes a U-shaped track having a clip for attachment of the stud to the track. The problems associated with installing shims, as discussed above, are also associated with installing such clips, and the installation of such clips can be difficult, time consuming, and increase the overall labor and construction costs. In addition, this known track assembly also requires that when the gypsum wallboard is installed, the top of the gypsum wallboard must be cut into a fluted configuration or another configuration in order for it to fit properly into the overhead structure. Having to specially cut the gypsum wallboard is difficult, time consumin
Lev Bruce A.
Peterka Karin E.
St. Germain Roger C. A.
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