Correct Answer - Option 1 : high-tensile steel
Concepts:
Pre-stressing is the process by which a concrete element is compressed, generally by steel wires or strands. Precast elements may be prestressed during the construction process (called pre-tensioning) or structures may be stressed once completed (called post-tensioning). Prestressing compensates for the tensile stresses introduced in concrete when the element is loaded. Hence, the concrete generally remains in compression.
This initial compression, in Prestressed Concrete structural elements like beam, column, is done by tendons, which are the high tensile strength steel wires. These are the medium through which tensile stresses are induced into the concrete. It maybe one single steel wire or a group of wires twisted together to develop required tensile stresses.
The pre-stressing steel, as per the IS code – 1343:1980, should be any one of the following types:
- Plain hard-drawn steel wires - Available in sizes of 2.5, 3, 4, 5, 7 and 8 mm diameter.
- Cold-drawn indented wire
- High tensile steel bar - - Available in sizes of 10, 12, 16, 20, 22, 25, 28 and 32 mm diameter
- Uncoated stress relieved strand.
Reinforcement used as un-tensioned steel should be one of the following types:
- Mild steel and medium tensile steel bars,
- Hot-rolled deformed bars,
- Cold-twisted bars, and
- Hard-drawn steel wire fabric.
