Pretensioning of wires for factory made prestressed concrete beams - uses jacking slide in pit to treat all wires of several lines simultaneously

摘要

The slide-mounted jack is used to stress wires or cables for precast prestressed beams. It permits the stressing and distressing of all wires simultaneously, and is sited in a pit at one end of the bed across several lines. A slide is fabricated from a welded stepped compound top plate on a grid of structural steel sections. It is set on rails in a pit which is cast in a concrete thrust block. The slide is capable of movement parallel to the cables, sitting nominally flush with the floor of the bed, locating a demountable comb, and being displaced b a single central jack bearing on the thrust block. The front edge of the slide is separated from the bed floor by a rectangular section vertically retractable wedge on screw jacks, and the comb locates wire ends which are anchored in the conventional manner.