Transcript PT Slab Cutting PBL Group Ltd. Mr. Prapat Boonlualoah Presentation by

PBL Group Ltd.
8/11 Soi Viphavadi 44, Viphavadi-Rangsit Road,
Lardyao, Jatujak,
Bangkok 10900,Thailand.
PT Slab Cutting
Presentation by
Mr. Prapat Boonlualoah
CEO, PBLFactory
Group Ltd.,
Bangkok
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General Considerations
In a typical post tensioned floor it is possible to locate penetrations of up
to 1000 by 3000 mm (3 by 9ft) between post tensioned tendons and to
require no other modification to the floor.
Penetrations that require cutting of the post tensioned tendons will need
to be checked and designed as would any large penetration in any floor
using bonded tendons is as follows:
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Slab Cutting Procedures –Bonded Tendon
1. Design the modified floor structure in the vicinity of the penetration
assuming that any cut post tensioned tendons are dead-ended at the
penetration.
2. Install any strengthening required.
3. Locate tendons and inspect grouting.
4. If there is no doubt as to the quality of the grouting, proceed to step5.
Otherwise
strip off ducting, clean out grout, and epoxy grout the
strands over length of 500 mm (20 in) immediately adjacent to the
penetration.
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Slab Cutting Procedures –Bonded Tendon
5. Install props.
6. Core drill the corners of the penetration to eliminate the need for over
cutting, and then cut the perimeter using a diamond saw.
7. Cut up the slab and remove.
8. Paint an epoxy-protective coating over the ends of the strands to prevent
corrosion.
9. Remove props.
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If a large penetration through a floor cannot be locate within the slab area
but must intersect a primary support beam, then substantial
strengthening of adjacent beans will usually be necessary.
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Slab Cutting – Unbonded Tendon
When cutting openings into floors built using unbonded post tensioned
tendons the procedures
used for bonded post tensioned tendons
cannot be applied. The preferred procedure that has been developed to
permit controlled cutting of unbonded
strands is to use a special
detensioning jack, The jack grips the strand and the strand is then cut,
with the force in the strands being released slowly. New anchorages are
then installed at each side of the new opening and the strands re-
stressed.
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Demolition of PT Slab
Extensive experience has been gained in demolition procedures for post
tensioned floors, and some general comments are made.
In bonded systems the procedures for demolition are the same as for
reinforced concrete. The individual strands
will not dislodge at
stressing anchorages.
In unbonded systems the strand capacity is lost over its entire length when
cut; therefore the floor will require back propping during demolition.
The individual cut strands will dislodge at stressing anchorages, but
will move generally less than 450 mm(18 in). However, precautions
should always be taken in case the strands move more than this.
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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PT Slab Cutting
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Project References
1.
The Emporium (Tower Zone) – Bonded
2. Fortune Complex
– Bonded and Unbonded
3. The Emerald Hotel
- Unbonded
4. Exim Bank
– Unbonded
5. Riverside Garden Marina
– Bonded
6. Atthenee Residence
– Bonded
7. Atthenee Tower
– Bonded
8. Empire Place
– Bonded
9. Riverine Place
– Bonded
10. CP Tower
– Unbonded
11. Manhattan Chidlom
- Bonded
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Thank You!
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