BONDED POST TENSIONED IN BUILDINGS
Bonded PT is almost maintenance free as the strands are bonded with the slab by the injected grout and become integrated part of the slabs or the beams,can result in saving of the reinforcement rebars because the strands which have more strength than the rebars are considered in the strength design (ultimate limit state)
The Bonded system in less sensitive to the failure of anchors of any reason because the strands are bonded with the concrete, not like the unbonded system which the anchor failure resulted in losing the stress on the whole length of the strand.The demolishing of the bonded PT floor dose not present any danger or safety concern.Drilling opening and whole in bonded PT system can be more easily and safe when alternation of the building is required.
ELEMENT OF BONDED PT SYSTEM
Plastic duct
Strand sample
Anchor Body
Galvanized ducts
Strands
Anchor Body
- Bonded system reduce the rebar requirement, less affected by Anchors failure and safer in demolition.
- Unbonded system has clear advantage in preventing successive failure due to punching shear.
- The new suggested Hybrid system of using both bonded and unbonded tendon in the same floor will have the advantages of boy systems.
- The unbonded tendons can by place banded easy over the columns lines and pass between the columns reinforcements.
- the stress in unbonded strand remain constant and will not be affected by the concrete strain.
- Incase of the punching shear failure during major earthquake, the unbonded tendon will engage with the slab and prevent catastrophic failure which may result in total collapse.
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