Helical binding reinforcement for concrete frames - stretches to increase pitch without plastic deformation and is of high strength steel

摘要

The contiguous helical binding reinforcement (5) for beams and columns in reinforced concrete frames has spring steel characteristics, i.e. can be stretched axially from an initially compressed form without plastic deformation of the constituent steel. The steel has high strength characteristics with an elastic limit in excess of 55 kg/mm2. The elastic properties enable the pitch of the contiguous binders to be varied to suit partic. structural requirements. The extremities of the bar may be formed into enlarged heads (51) and the binding is made by heating, bending and finally cooling a straight bar with helicoidal grooving. The bar may be heated by oven or by induction bobbin and may be bent by winding onto a rotating former. The primary bar may be heated up to ordinary tempering temps. ie 200 to 240 deg.C.