Question

The losses in prestress in pre-tensioning system are due to

Select the correct answer using the codes given below:

• A. 1,2 and 3
• B. 2 and 3
• C. 1 alone
• D. 3 alone

Answer 1

The correct option is D 3 alone

$\text{Loss of prestress in pre-tensioned members:}$
(i) Losses due to creep and shrinkage of concrete.
(ii) Losses due to elastic shortening of concrete.
(iii) Losses due to relaxation.
$\text{Loss of prestress in post- tensioned members:}$
(i) Loss due to friction (length effect, curvature effect).
(ii) Losses at anchoring stage.
(iii) Losses due to creep and shrinkage of concrete.
(iv) Losses due to successive tensioning of wires.
(v) Losses due to relaxation.
Loss of stress due to elastic shortening of concrete is maximum in pretensioned members. In the case of post-tensioned members these losses occur only when a number of cables are progressively stressed one after another.