Beam of concrete or prestressable light concrete with most economical cross sectional design as possible is pretensioned by single seven wire strand, and has additional structurally unstressed reinforcement coil encompassing wire

摘要

The beam of concrete or prestressable light concrete, with a most economical cross sectional design as possible, is pretensioned by a single seven wire strand (C). The beam is machine produced, and the additional structurally unstressed reinforcement encompassing the wire has the form of a coil (D) which is first wound compactly and then stretched out to a step width to suit purpose. The coil is provided with two welded in longitudinal rods.