Bridges – Arch – Abutments and anchorages
Reexamination Certificate
1999-07-29
2001-03-27
Lillis, Eileen D. (Department: 3671)
Bridges
Arch
Abutments and anchorages
C014S024000, C014S077100, C405S124000, C405S126000, C052S086000, C052S320000
Reexamination Certificate
active
06205605
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the construction of vaulted structures such as underpasses or overpasses for roads and motorways and other similar constructions.
BACKGROUND OF THE INVENTION
The document SAMFLO FR 2 751 675 discloses a method of construction of a vault, in which two half-shells, provided with a lip and bearing braces, are positioned on continuous footings constructed on site. The two half-shells are then brought to bear against one another, by means of the braces, and a continuity keystone is cast between the upper edges of the two half-shells, on the lips, so as to construct a keystone which brings about continuous transverse joining together of the half-shells.
The braces, by means of which the half-shells bear against one another before the keystone is formed, are embedded in the concrete and are thus lost. However, these braces make up a certain percentage of the cost of construction of a vault. The applicant has therefore sought to reduce the cost induced by these braces.
From FR 2 723 116 (PREFAC), a method of construction of a vault using at least two half-shells each comprising a bottom lip was known, in which the two half-shells are brought to bear against one another, lip against lip, with a compressible block being interposed, and, in order to avoid any relative escape of the two half-shells and thus achieve secure bearing, the two lips are connected by means of a metal plate which is fixed to the lower faces of the lips. The plate is positioned after the block and, consequently, after the compression of the latter and after the half-shells have been brought to bear against one another. The result is that the plate does not participate in the half-shells being brought to bear against one another. Concrete is then cast onto the bottom lips, between the two half-shells, so as to produce a longitudinal keystone beam.
In the PREFAC invention, the block and the plate are normally removable. However, as the block is compressed between the two half-shells, it proves impossible to remove it later. Moreover, if the block is interposed between the lips, it is the latter which support the bearing load of the two half-shells on one another, even after the keystone concrete has been cast, and not the longitudinal keystone beam. The result is that the vault constructed in this manner is liable to premature wear.
In the SAMFLO invention (FR 2 751 675), there is no transfer of the bearing load from the braces to the keystone either. Indeed, it is by means of the braces, embedded in the concrete, that the half-shells bear against one another not only before the concrete is cast but after casting also.
SUMMARY OF THE INVENTION
To this end, the invention relates to a method of construction of a vault, in which at least two half-shells are brought to bear against one another by means of at least two bearing pieces which are mated and, each half-shell comprising an upper edge and a bottom lip, a keystone-forming material is cast between said upper edges, on the bottom constituted by the lips, so as to bring about continuous transverse joining together of the half-shells, which method is characterized in that each bearing piece is fixed removably to a half-shell, the two half-shells are brought to bear against one another temporarily via their bearing piece without their bottom lips being brought to bear against one another, and the bearing pieces are removed after the keystone-forming material has been cast, so as to effect load transfer from the bearing pieces to the half-shells.
By virtue of the invention, the bearing braces can be reused later for the construction of another vault.
In the present invention, by virtue of the removal of the bearing pieces, load transfer from the bearing pieces to the half-shells is effected with certainty.
It is possible to arrange the bearing pieces at least partly above the half-shells or at least partly below the half-shells.
In the prior art, the braces cluttered the space between the two half-shells and consequently obstructed the installation of continuity reinforcement. By virtue of the invention, this disadvantage is also eliminated.
In a particular embodiment, two pluralities of half-shells are placed end to end in two longitudinal rows and each half-shell of one of the rows is brought to bear against a half-shell of the other row by means of at least two bearing pieces, male and female respectively, which are mated so that the bearing pieces of one of the two types support the bearing pieces of the other type.
By virtue of this, the bearing points of the half-shells on one another are all at the same level, which ensures greater stability of the vault and a completely continuous appearance on the soffit.
The invention also relates to a bearing piece for bringing about the bearing against one another of the half-shells of the vault constructed according to the above method, comprising a transverse bearing arm, which piece comprises removable fixing means essentially at right angles to the transverse arm.
The invention also relates to a half-shell for construction of the vault according to the above method, which half-shell comprises means of receiving a bearing piece.
REFERENCES:
patent: 571225 (1896-11-01), Geisel
patent: 886666 (1908-05-01), Thomas
patent: 3374497 (1968-03-01), Meheen
patent: 4349491 (1982-09-01), Eyden
patent: 5503504 (1996-04-01), Hess et al.
patent: 495 469 (1970-08-01), None
patent: 2 751 675 (1998-01-01), None
patent: WO 9603552 (1996-02-01), None
Freyssinet International (Stup)
Hartmann Gary S.
Lillis Eileen D.
Pennie & Edmonds LLP
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