Static structures (e.g. – buildings) – Relatively yieldable preformed separator
Reexamination Certificate
2001-06-27
2002-08-13
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Relatively yieldable preformed separator
C052S395000, C052S396040, C052S463000, C052S460000, C052S470000
Reexamination Certificate
active
06430884
ABSTRACT:
BACKGROUND OF THE INVENTION
Seismic expansion joint covers for buildings in geographic regions that are prone to earthquakes are of special designs that allow for movements of the building units on either side of the expansion gap that are very much greater than the movements that occur as a result of thermal expansion and contraction. In that regard, buildings currently being built in earthquake-prone regions are usually supported on isolators that attenuate the intensities of shocks imparted to the building structure but increase the durations and magnitudes of the swaying motions of the structure as the structure displaces and deforms when forces due to the earthquake are imposed on its foundation supports. When a building is composed of two or more adjacent independent structural units, each structural unit is subject to movements in an earthquake that are different in direction, frequency and magnitude. That is the case, indeed, regardless of whether the units are mounted on isolators or not.
Adjacent structural units of a building are, in particular, subject to large relative movements having components horizontally toward and away from each other (perpendicular to the gap)—x-axis movements—and components horizontally parallel to the gap—y-axis movements. Because the connections between structural units at expansion joints (which might better be termed “motion-absorbing gaps”) occur at the perimeters of the structural units, the movements include small but meaningful relative displacements vertically and angularly between portions on opposite sides of gaps due to the rocking of the floors at the perimeter of the structural unit about a fulcrum in the region of the bottom center of the structural unit.
U.S. Pat. No. 5,644,879 (Shreiner et al., Jul. 8, 1997), which is owned by the assignee of the present invention and is hereby incorporated herein by reference for all purposes, describes and shows a seismic expansion joint cover assembly that is adapted to span a gap between the floors of building sections on opposite sides of a motion-absorbing gap and that permits relative movements of the floors substantially horizontally toward and away from each other along an axis perpendicular to the gap (“x-axis direction”) and substantially horizontally relative to each other along an axis parallel to the gap (“y-axis direction”). The assembly includes a rectangular structural floor bridge panel that spans the gap in all relative positions of the floors. One end of the bridge panel is attached to the floor on one side of the gap (“floor A”) for movement in the y-axis direction and against movement in the x-axis direction relative to floor A. The other end of the bridge panel is supported on the floor of the other building section (“floor B”) for movement in the x-axis direction and against movement in the y-axis direction relative to floor B.
U.S. Pat. No. 5,666,775 (Shreiner et al., Sep. 16, 1997), which is also owned by the assignee of the present invention and is also hereby incorporated herein by reference for all purposes, describes and shows a wall expansion joint cover that is secured to the wall members on opposite sides of an expansion gap by hook and loop fasteners and is tethered to the wall by cords so that it is prevented from falling to the floor and becoming a safety hazard by impeding passage of persons across the gap during and after an earthquake dislodges it. U. S. Pat. No. 5,794,456 (Shreiner et al., Sept. 1, 1998), another patent owned by the assignee of the present invention (and hereby incorporated herein by reference for all purposes), discloses elastic cords for keeping a wall expansion joint cover centered in a motion-absorbing gap.
Both wall expansion joint covers (interior and exterior) and ceiling expansion joint covers are subject to conditions that differ somewhat from those of floor expansion joint covers. In the case of walls, the cover panel that extends across and covers the motion-absorbing gap lies vertically. Therefore, the cover panel has to be configured and installed in a manner that allows relative movements of structural units of the building perpendicular to the plane of the cover of much greater magnitudes than those of floor expansion joint covers. Exterior wall expansion joint covers are subject to high wind loads acting both toward and away from the building wall on which they are installed. Floor expansion joint covers are subject only to downward vertical loads (due to persons and objects moving across them)—gravity holds them down. The covers of wall expansion joint covers that are dislodged in whole or in part from the expansion gap do not return automatically to their installed positions after dislodgment by an earthquake. Floor expansion joint covers usually reseat automatically when an earthquake ceases. Although reseating of interior expansion joint covers is not difficult, because they are generally accessible to workers from within the building, immediate reseating of interior wall expansion joint covers to close the relatively large motion-absorbing gap is important to the safety of persons that occupy the building after an earthquake. Reseating of exterior wall expansion joint covers above the ground floor, though not required immediately except possibly in bad weather to prevent intrusion of rain or snow, requires workers to climb ladders or be lowered on cable-supported work platforms to gain access to the wall covers.
Ceiling expansion joint covers are subject to the same relative motions as floor expansion joint covers. Whereas floor expansion joint covers are essentially self-seating by gravity, ceiling expansion joint covers must be fastened against gravity. Like wall expansion joint covers, ceiling expansion joint covers can be reseated from within the building. It is desirable, however, for convenience and safety that they not be permitted to move appreciably away from the plane of the ceiling when they are dislodged in an earthquake.
Although the expansion joint covers disclosed in the aforementioned patents and various other previously known expansion joint covers meet the requirements imposed on them reasonably well, there is a need for wall and ceiling expansion joint covers that are relatively simple in construction and function, relatively inexpensive to produce and install, capable of reseating automatically after the end of an earthquake that dislodges them, and versatile as far as utility in various environments is concerned. Further desirable objectives that are not fully met by many previously known wall and ceiling expansion joint covers include light weight cover panels, which minimizes dynamic loads exerted on various parts of the expansion joint cover system, and reliable, long-lived functional elements, which resist damage and enable a long service life of an installation without repair or replacement.
SUMMARY OF THE INVENTION
The foregoing needs and objectives are met, in accordance with the present invention, by a seismic expansion joint cover assembly installed at a motion-absorbing gap between a member A on one side of the gap and a member B on the other side of the gap. The assembly includes a cover panel spanning the gap and a hinge joining one edge A of the cover panel to the member A for pivotal movement about a pivot axis. The pivot axis is spaced apart from the expansion gap so as to enable a stop between the cover panel and member A to prevent the cover panel from pivoting about the pivot axis into the expansion gap upon widening of the expansion gap. A permanent magnet and magnet striker releasably secure the other edge B of the cover panel to the member B.
The hinged connection of the end A of the cover panel to the member A leaves the end B free to swing out a considerable distance when member B moves relative to member A such as to engage the cover panel and to release the magnetic connection. That aspect of the invention is especially useful for interior and exterior wall covers, in which the cover panels are vertical and the members A and B displace relative to one another horizon
Barr Roger W.
Morris Nathan
Shreiner Thomas A.
Baker & Botts L.L.P.
Construction Specialties, Inc.
Friedman Carl D.
Katcheves Basil
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