Correct Answer - Option 1 : Bonded beams
Concept:
Bonded post-tension:
- If concreting is done over the tendons directly, then a bond forms between concrete and tendons.
- It helps to transfer the forces using a bond mechanism.
Unbounded post-tension:
- when concreting is done using ducts for the tendons, then tendons don't come in contact with concrete, and hence no bonds formed.
- All the forces are transferred to the concrete by end blocks.
The rate of increase of stress is larger in the case of bonded beams than in unbonded .incase of unbounded beams, the tendons are free to elongate independently throughout their length under the action of transverse loads on the beam
