Question

At the time of initial tensioning, the maximum tensile stress f_pi immediately behind the anchorage shall not exceed ______ of the ultimate tensile strength f_pu of the wire of bar or stand.

1. 55%
2. 69%
3. 76%
4. 85%

Answer 1

Correct Answer - Option 3 : 76%

Explanation:

• As per CI. 18.5.1 of IS 1343 at the time of initial tensing, the maximum tensile stress immediately behind the anchorages shall not exceed 80% of the ultimate tensile strength of wire or bar or strand.

As per the given option, we should take 76% (for the safer side)

•  Grade of concrete:
  • M 40 for pre-tensioned members
  • M 30 for post-tensioned members