Static structures (e.g. – buildings) – With component having discrete prestressing means – Beam – girder – or truss construction
Patent
1975-09-29
1977-08-16
Perham, Alfred C.
Static structures (e.g., buildings)
With component having discrete prestressing means
Beam, girder, or truss construction
52374, 52508, E04B 141, E04C 318
Patent
active
040416640
ABSTRACT:
A structural element having a fire rating of approximately two hours when tested with the standard time-temperature curve established by the American Standards for Testing Materials, said element including prestressed concrete joists each having a plate-like body portion and reinforced support ledges, each ledge has a nailing strip molded adjacent the bottom thereof and each nailing strip including a penetratable area formed internally adjacent thereof, a plurality of sheets of material disposed adjacent the ends of said ledges, each sheet of material forming a butt joint with an adjacent sheet which extends longitudinally along one of said ledges, channel-shaped members disposed along each butt joint intermediate said ledge portion and said sheets and attachment means for attaching said channel-shaped members to the nailing strips and, also, for attaching sheets of material to said nailing strips and channel-shaped members whereby said sheets of material are secured to the joist while preventing undesirable distortion or warping thereof during the fire rating tests. A pretensioned concrete joist of the T-type comprising a concrete plate-like body portion, a channel-shaped support ledge, a nailing strip integrally molded in the bottom of said ledge, said nailing strip including a channel-shaped member having a penetratable layer of material disposed therein and a plurality of positioning members longitudinally spaced along said channel-shaped member, and pretensioning steel disposed in engagement with said positioning members, said pretensioning steel and said positioning members cooperating to maintain the nailing strip on the bottom surface of the ledge prior to and during placement of the concrete of said joist. A novel form member for producing a pretensioned concrete member having a nailing strip molded therein, and a novel positioning member made from a single piece of plastic material.
REFERENCES:
patent: 955338 (1910-04-01), Leiter
patent: 1563593 (1925-12-01), Schall
patent: 2010294 (1935-08-01), Dovell
patent: 2101001 (1937-11-01), Balduf
patent: 2432622 (1947-12-01), Johnston
patent: 3283456 (1966-11-01), Carlton
patent: 3567816 (1971-03-01), Embree
Burton Duane
Perham Alfred C.
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