High tensile bars
As an alternative to wires or strand, high tensile steel bars may be used. (These are obviously significantly stiffer and hence may only be used in situations in which the prestressing force runs in a straight line.) Bar diameters range from 25 mm to 75 mm, with characteristic strengths in the region of 1000 N/mm2. The bars are supplied in standard lengths with rolled threads on the ends.
The relevant British Standard is BS 4486, Specification for hot rolled and hot rolled and processed high tensile alloy steel bars for the prestressing of concrete. This gives the requirements for preferred sizes of bars.