AN IMPROVED METHOD FOR PRESTRESSING REINFORCED CONCRETE BEAMS AND AN APPARATUS THEREFOR

摘要

1,245,002. Moulding prestressed concrete beams. LEONARD FAIRCLOUGH Ltd. 23 Sept., 1969 [24 Sept., 1968], No. 45215/68. Heading B5A. [Also in Division E1] Prestressing of I-section concrete beams A is carried out by tensioning longitudinal wire strands B through a lower region of the beam and then deflecting upper additional strands b subjected to a lower tension through the web of the beam into the lower region. Devices (C) hold down the additional strands b and are set into the concrete. Devices DSP1/SP hold the additional strands up and are out of the concrete. The lower hold down devices (C) are held by short lengths of wire cSP1/SP secured to a frame cSP3/SP of a bedplate (a) on which rests the beam supported by shuttering, by means of wedges cSP4/SP. Several beams A may be prestressed by reinforcements in tandem, the reinforcing wires b, B and the wires cSP1/SP being cut flush with the concrete to release the beams when the concrete has set.