Static structures (e.g. – buildings) – Assembled in situ-type anchor or tie – Sheet or wire tie
Reexamination Certificate
1999-12-31
2001-10-02
Callo, Laura A. (Department: 3635)
Static structures (e.g., buildings)
Assembled in situ-type anchor or tie
Sheet or wire tie
C052S715000, C052S092200, C052S093100, C403S232100
Reexamination Certificate
active
06295781
ABSTRACT:
BACKGROUND-DESCRIPTION OF PRIOR ART
Background
Recent studies of hurricane damage on wood-frame buildings indicate that the most extensive destruction to a house by strong winds, was when the roof was lifted from the wall, and rain ruined everything in the house.
Seismic forces can shake a house, moving the heavier roof at a different speed than the walls. If the wall and roof are not tied firmly together, these forces can detach the rafters from the top plate causing the walls to buckle and fall.
The roof system provides stability to a house by bracing the tops of exterior and interior load-bearing walls. Sheet metal joints perform better than nailed joints in high winds and during seismic activity. This invention, secured by well placed fasteners, will insure that the major structural members of a house, the roof and walls, are securely tied together.
Hurricanes
After Hurricane Andrew, roofs were blown off buildings, walls were blown out, and many homes were completely destroyed. Toe-nailed connections, missing hurricane clips, and misused, under-secured, or undersize hurricane clips caused most roofs to become detached from the walls.
The engineering staff of the American Plywood Association provided technical personnel to assess the damage from Hurricane Andrew in Florida. The majority of wood structural sheathing failures were attributed to improper connection details, and in every case investigated, the sheathing loss was a result of improper nailing (Keith, 1992).
These problems have not been solved because staples are still used to tie down sheathing, and rafters and trusses are still toe-nailed to the top plate. By looking at new construction, nails can be seen poking through the roof sheathing, completely missing the roof rafter. Most conscientious framers would drive another nail when they felt the nail miss the underlying rafter, but with the new powered nail guns, the framer can not tell if the rafter was missed because each shot feels the same, no matter what the nail is being driven into. This is the same with wall sheathing and wall studs.
Earthquakes
During an earthquake, the wall and roof diaphragms undergo shearing and bending. The shear forces from the roof boundary members are transferred to the top of the shear wall (outside wall) by way of toenails or blocking to the top plate. To withstand and transfer the shear loads, plywood sheets have to be spliced together to prevent adjoining edges from sliding past or over each other (Gray, 1990). This invention prevents the wall sheathing from sliding over or past each other, and ties this sheathing to the top plate, wall stud, and indirectly, to the rafter.
Steel connectors, between different components of a wood-frame buildings superstructure, provide continuity so that the building will move as a unit in response to seismic activity (Yanev, 1974). This invention uses a steel connector to tie the major structural elements of a building together including the rafter, top plate, wall stud, and wall sheathing.
Prior Art
A number of connectors have been developed to tie together the structural members of the roof and wall of a house under construction. Up until this invention, nobody had seen how to make a connector that could tie wall sheathing to these underlying structural members.
The following patents are related to tying structural members of a house together. Linehan's U.S. Pat. No 2,321,221 ties together two intersecting structural members. Maxwell's U.S. Pat. No. 2,413,362 ties together ties together intersecting structural members and resists shear forces. Banse's U.S. Pat. No. 3,256,030 ties together intersecting structural members.
The following patents tie together a rafter and top plate: Gib's U.S. Pat. Nos. 4,410,294 and 4,572,695; Commins' U.S. Pat. No. 4,714,372; Colonias' U.S. Pat. No. 5,109,646; Callies' U.S. Pat. No. 5,230,198; Frye's U.S. Pat. No. 5,311,708; Stuart's U.S. Pat. No. 5,335,469; Mc Donald's U.S. Pat. No. 5,560,156; and Newman's U.S. Pat. No. 5,448,871.
None of the above inventions tie the rafter, top plate, and wall stud together. Haswell's U.S. Pat. No. 5,640,822 and Kalker's U.S. Pat. No. 5,732,524 tie the rafter, top plate, and the weak thin edge of the wall stud together, but they don't tie the wall sheathing to these structural members. The Simpson Strong-Tie Company catalog shows three connectors that tie the rafter, top plate, and wall stud together. Their H
2
, H
15
, and H
7
can tie each structural member together, but does not clamp the top plate tightly together, nor do they tie the wall sheathing to the structural members.
OBJECTS AND ADVANTAGES
Accordingly, several objects and advantages of my invention are that it helps secure the roof and wall of a building together, to keep the building from being destroyed by hurricanes, tornadoes, and earthquakes.
This invention helps prevent the wall of a building from detaching from the roof during a hurricane. It makes the wall into a stable shear-wall during an earthquake, transferring shear forces into the foundation and ground.
This invention helps prevent the roof rafters or roof trusses from separating from the wall during a hurricane by tying the wall sheathing securely to the underlying top plate and wall stud, transferring lateral and uplift forces to the walls and to the foundation, without sliding or detaching. It also makes sure that any forces transferred from the roof can be managed by the wall and transferred properly to the ground.
During an earthquake or a hurricane, a building with my invention will keep the roof and walls together as a sturdy unit, resisting and transferring destructive forces to the ground.
Mounted on the wall sheathing, wall stud, top plate, and rafter, my invention resists uplift, the most destructive force during a hurricane. During an earthquake, when my invention is mounted on the roof and walls, they will turn each member into a shear-wall, with high resistance to racking. This would improve the house beyond existing building codes, as sheet metal joints have been proven to perform better than nailed joints during hurricanes and earthquakes.
Another object of this invention is the large surface area which prevents the wood from splitting during nailing or during uplift or racking forces. The large surface area provides more strength in the connecting or hold-down process.
Still another advantage is the accurately placed nail holes on the invention. These nail holes prevent nails from splitting the underlying rafter and stud, by making the framer place nails at the correct and accurate location. The accurate nail holes also prevent splitting of the wall sheathing.
Another advantage is that the nails are driven into the strong broad-side of a rafter, stud, or joist. The invention also wraps around three sides of the top plate, forming a very strong connection and preventing the two plates of the top plate from pulling apart.
Yet another advantage of this invention is during earthquakes, nails can sometimes bend with the movements of the house, but screws often break. Even though screws hold tighter than nails and provide a tight connection against uplifting forces from hurricanes, they are less resistant against earth movements. This invention absorbs and transmits most of the forces during an earthquake and hurricane so nails and/or screws can be used as fasteners.
Another advantage is that since the invention absorbs and transfers earthquake and hurricane forces, less nails and nailing could be used. Also, screws could be used in the invention in earthquake areas with less fear that the heads will shear off.
Previously, only nails had to shear, but this entire connector must be sheared for the invention to fail. With this strong connector, rafters will not have to be “birds-mouthed” to fit on the top plate. A birds-mouth weakens the rafter and requires a skilled and expensive carpenter.
Still another advantage is that with the wall sheathing firmly attached to the rafters, wall material will now have a better chanc
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