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Pre-stressed Steel System Post Tensioned Slab

Pre-stressed Steel System Post Tensioned Slab . Case Study: K- Financial Tower. K- FINANCIAL TOWERS. BENEFITS. Less Columns Less Beams Thinner slabs Controlled deflection Flexibility of Layout & Services Lighter Structure Less Foundations Less Rebars  Less Workmanship

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Pre-stressed Steel System Post Tensioned Slab

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  1. Pre-stressed Steel System Post Tensioned Slab Case Study: K- Financial Tower

  2. K- FINANCIAL TOWERS

  3. BENEFITS • Less Columns • Less Beams • Thinner slabs • Controlled deflection • Flexibility of Layout & Services • Lighter Structure • Less Foundations • Less Rebars  Less Workmanship • Better Durability • Quicker turn-around of the Formwork • Fast Construction • Cost Saving

  4. PRINCIPLES OF PRESTRESSING

  5. Tendon Three-span post-tensioned beam V a 2 P cos P W B a a P P P For harped profile A 8P x sag w = For parabolic shape 2 L Free-body diagram of a tendon section between its low point (A) and point of inflection (B) Illustrative example • Illustrative

  6. W Va Vd P P Free-body diagram of beam after removal of tendon Va Vd W P P Free-body diagram of tendon Force system between tendon and beam Illustrative example • Illustrative

  7. Flat corrugated duct Strand position in a circular duct Bonded system tendon detail for beams & slabs BONDED • How it is bonded: • Bond is achieved throughout the length of the tendon by a cementitious matrix called grout • PT force along the tendon is a function of the deformation of the concrete

  8. K - FINANCIAL TOWERS TYPICAL FLOORS

  9. SLAB MESHING

  10. LATITUDE TENDONS

  11. LONGITUDE TENDONS

  12. Ultimate moment Mx

  13. Ultimate moment My

  14. Service Bottom X stress Plan

  15. Service Bottom Y stress Plan

  16. Service Top X stress Plan

  17. Service Top Y stress Plan

  18. Long term deflection plan

  19. Execution By nominated local installation agent

  20. SUMMARY OF POST-TENSIONING EXECUTION

  21. POST-TENSIONING INSTALLATION • FORMWORK • SIDE-SHUTTER • FIXING OF ANCHORS • MARKING OF THE SLAB • TENDON INSTALLATION • PROFILING & FINISHING

  22. CHECKING BEFORE THE CASTING • No. OF ANCHORS AND TENDONS • PROFILES • GROUT VENTS • BURSTING REINFORCEMENT • Additional Rebar (Bursting, Punching Shear) • PROPPING AND FORMWORK

  23. CASTING • PROPER VIBRATION AROUND THE ANCHORS • CONCRETE TO BE PLACED WITHOUT DAMAGING THE TENDONS • PROPER CURING OF THE CONCRETE AFTER THE CASTING

  24. STRESSING • REMOVE THE SIDE-SHUTTER • CRUSH CUBE FOR TESTING THE CONCRETE STRENGTH • START STRESSING TO 100% IF CONCRETE IS AT 25 MPA IN LESS THAN 3 DAYS • DO PARTIAL STRESSING IF REQUIRED • TAKE READINGS AFTER

  25. APPROVAL • SEND STRESSING RECORDS TO THE P/T CONSULTANT FOR APPROVAL • CUT THE TAILS AFTER APPROVAL • FILL THE POCKETS • PREPARE FOR GROUTING

  26. GROUTING • SHUTTER CAN BE REMOVED • ADEQUATE PROPPING TO BE PLACED • GROUTING OPERATIONS CAN START AT ANY TIME

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