Lecture CiTG
Underwater concrete floors
ir. Ruud Arkesteijn
29th of September 2015
Content
1st hour:
• Use and functions of UCF’s
• Distribution of forces
2nd hour:
• Design-rules (CUR77)
• Case: guideline...
Use of UCF’s
Conditions for application in building pits:
1. sub-surface construction in ‘soft soils’…
2. below the ground...
Bouwput en fasering
Bouwput en fasering
Bouwput en fasering
Bouwput en fasering
Bouwput en fasering
Bouwput en fasering
Bouwput en fasering
Bouwput en fasering
Bouwput en fasering
Functions of UCF’s
1. Water retaining layer
2. Horizontal force equilibrium (strut)
3. Vertical force equilibrium (up burs...
Bouwput en fasering
Distribution of forces
4 mechanisms:
• Boundary-disturbance à “Randstoringseffect”
• Arching à “Boogwerking”
• Membrane-ef...
Boundary-disturbance à “Randstoringseffect”
Arching à “Boogwerking”
Membrane-effect à “Membraanwerking”
Arching & membrane-effect
Re-distribution of forces à “Krachtenherverdeling”
Ultimate limit states
1) Bending moments (tension)
2) Bending moments in arch (compression)
3) Shear failure (near retaini...
Design rules (CUR77)
CUR77 provides
guidelines for design
of unreinforced UCF’s
with respect to:
• Schematisation
• Modell...
• Longitudinal (“lange richting”):
à no boundary-disturbance
à normal forces absent
à membrane-effect is big!
• Cross-sect...
à hgem = average height (minimum 800mm?)
à tolerances on floor thickness
à calculate stresses with:
hmin = hgem - √(tolond...
Modelling
à beam-model of cross-section
Longitudinal:
à
Serviceability Limit State (SLS)
à dry building pit
à discrete cracking (minimal compression-zone)
2
, ,
1...
Ultimate Limit State (ULS)
à structural safety
à incl. material and load factors
Longitudinal:
à no check because of membr...
New in revised CUR77 (v2014):
1. Revised according to Eurocode 2 (NEN-EN1992)
2. No design rules for SLS in cross sectiona...
Not in CUR77…
Hydration of concrete produces heat à temp. in UCF to 30-45oC
Cooling after heating à shrinkage
Strength of ...
Verificatie en toepasbaarheid
Case
à Use CUR77:2001 (on Blackboard)
à Consider an unreinforced UCF (no addition of steel fibres)
Make a preliminary desi...
Case: guidelines for preliminary design of UCF
1. Choose concrete strength class B25 (nowadays C20/25):
à tensional streng...
Case: guidelines for preliminary design of UCF
3. Determine effective load on piles based on:
Lx * Ly * Pwater pressure–we...
Case: guidelines for preliminary design of UCF
5. Determine normal forces in UCF (with D-Sheet Piling):
à suggested modell...
Case: guidelines for preliminary design of UCF
6. Check safety in arching-mechanism (ULS cross-sectional direction)
Steel fibre reinforced UCF
Potsdammer Platz Berlijn
(1997)
In the Netherlands:
• Heinoseweg Zwolle
(1998)
• Betuweroute
(1...
Staalvezelversterkt OWB
“After-crack-behaviour”
à Tensional strength ≈
à Early tensional strength
à Tensional strength aft...
Moment capacity for UCF with steelfibres
à example for UCF with hmin = 700 mm and N’ = 200 kN/m’
à 30 kg/m3 of steelfibres...
Projects
Groninger Forum
Projects
Groninger Forum
Link to video (dutch) of the process of
pooring the UCF with steel fibres for
project Groninger Forum:
https://vimeo.com/8...
Projects
Mauritshuis (The Hague)
Mauritshuis (The Hague)
Mauritshuis
Link to video (dutch) with animations
made by diving company C.O.W.:
https://vimeo.com/24826624
Lecture CiTG
Innovations…
Traditional building method:
- Unreinforced UCF with
temporary function
- Reinforced concrete floor
has perma...
Lecture CiTG 29th of September 2015
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Sheets used for lecture on 4th of june 2013 at TU Delft for course CIE4363 (Foundation and deep excavations)

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Presentation for lecture on underwater concrete - TU Delft: MSc Geotechnical Engineering

  1. 1. Lecture CiTG Underwater concrete floors ir. Ruud Arkesteijn 29th of September 2015
  2. 2. Content 1st hour: • Use and functions of UCF’s • Distribution of forces 2nd hour: • Design-rules (CUR77) • Case: guidelines for preliminary design Extra: • Steel fibre reinforced UCF’s • Projects • Innovations
  3. 3. Use of UCF’s Conditions for application in building pits: 1. sub-surface construction in ‘soft soils’… 2. below the groundwater level… 3. especially in permeable soils. Typical Delta/Dutch conditions!
  4. 4. Bouwput en fasering
  5. 5. Bouwput en fasering
  6. 6. Bouwput en fasering
  7. 7. Bouwput en fasering
  8. 8. Bouwput en fasering
  9. 9. Bouwput en fasering
  10. 10. Bouwput en fasering
  11. 11. Bouwput en fasering
  12. 12. Bouwput en fasering
  13. 13. Functions of UCF’s 1. Water retaining layer 2. Horizontal force equilibrium (strut) 3. Vertical force equilibrium (up burst / heave) Often a combination of the above!
  14. 14. Bouwput en fasering
  15. 15. Distribution of forces 4 mechanisms: • Boundary-disturbance à “Randstoringseffect” • Arching à “Boogwerking” • Membrane-effect à “Membraanwerking” • Re-distribution of forces à “Krachtenherverdeling”
  16. 16. Boundary-disturbance à “Randstoringseffect”
  17. 17. Arching à “Boogwerking”
  18. 18. Membrane-effect à “Membraanwerking”
  19. 19. Arching & membrane-effect
  20. 20. Re-distribution of forces à “Krachtenherverdeling”
  21. 21. Ultimate limit states 1) Bending moments (tension) 2) Bending moments in arch (compression) 3) Shear failure (near retaining wall) 4) Failure or slipping at retaining wall 5) Pull-out of retaining wall (geotechnical failure) 6) Failure of connection with tension piles (punching shear) 7) Pull-out of tension piles (structural or geotechnical failure)
  22. 22. Design rules (CUR77) CUR77 provides guidelines for design of unreinforced UCF’s with respect to: • Schematisation • Modelling • Dimensioning • Detailing Revision in 2014! Demand is to comply with Eurocodes (0, 2 & 7)!
  23. 23. • Longitudinal (“lange richting”): à no boundary-disturbance à normal forces absent à membrane-effect is big! • Cross-sectional (“korte richting”): à boundary-disturbance is critical à normal forces present (strut-function) à limited membrane-effect Assumption: Schematisation #1 “lange” richting “korte” richting onderwaterbetonvloer damwand palen Ly Lx Ly =< Lx CUR77:2001+2014
  24. 24. à hgem = average height (minimum 800mm?) à tolerances on floor thickness à calculate stresses with: hmin = hgem - √(tolonder 2+ tolboven 2) Schematisation #2 Guidelines: tolonder à 250 mm for peat/clay à 150 mm for sand/gravel tolboven à 75 mm for hob-dobber à higher for slopes?
  25. 25. Modelling à beam-model of cross-section
  26. 26. Longitudinal: à Serviceability Limit State (SLS) à dry building pit à discrete cracking (minimal compression-zone) 2 , , 1 (without N') 8 s rep y r repq L M£× × Cross-sectional: à uncracked or with arching or with arching + re-dristribution of forces , ,mod , (with N')s rep el r repM M£
  27. 27. Ultimate Limit State (ULS) à structural safety à incl. material and load factors Longitudinal: à no check because of membrane-effect! Cross sectional: à uncracked or with arching and infinite re-distribution of forces (local): , ,mod , (with N' )s d el r d dM M£ 2 , , 1 8 s d s d xM q L= × ×
  28. 28. New in revised CUR77 (v2014): 1. Revised according to Eurocode 2 (NEN-EN1992) 2. No design rules for SLS in cross sectional direction 3. Optimization of arch-height (z) in ULS 4. Check on shear forces near retaining wall 5. Safety check for case of UCF slipping at retaining wall 6. Adjustments for disc-shape-connections (micro piles): - extra safety factor kr for punching shear - increased capacity of concrete compression strength under discs 7. Calculation of axial stiffness piles based on secant-value à according to CUR236 : Anchor-piles 8. Calculation method for optimization with membrane force 9. Guidelines for use of 2D calculation models Latest developments published in Cement 2013/3 and Cement 2014/?
  29. 29. Not in CUR77… Hydration of concrete produces heat à temp. in UCF to 30-45oC Cooling after heating à shrinkage Strength of concrete at 50% à sensitive for cracking Thermal shrinkage of concrete: à In relatively big building pits the risk of water-conducting cracks to occur is high even before pumping out the water !
  30. 30. Verificatie en toepasbaarheid
  31. 31. Case à Use CUR77:2001 (on Blackboard) à Consider an unreinforced UCF (no addition of steel fibres) Make a preliminary design for a deep building pit: à Modelling a beam-model is not necessary… à Do not check SLS in cross-sectional direction! à Only check SLS longitudinal direction, punching shear, and equilibrium in arch
  32. 32. Case: guidelines for preliminary design of UCF 1. Choose concrete strength class B25 (nowadays C20/25): à tensional strength fb = 1,15 N/mm2 à compression strength f’b = 18,0 N/mm2 2. Determine Ly using SLS check in longitudinal direction (CUR77). Choose Lx >= Ly (for edge piles distance to retaining wall Lx,edge < Lx ) LxLx,edge
  33. 33. Case: guidelines for preliminary design of UCF 3. Determine effective load on piles based on: Lx * Ly * Pwater pressure–weight of UCF (incl. load factors) 4. Check punching shear (CUR77). Adjust hgem or Lx if needed/possible.
  34. 34. Case: guidelines for preliminary design of UCF 5. Determine normal forces in UCF (with D-Sheet Piling): à suggested modelling:
  35. 35. Case: guidelines for preliminary design of UCF 6. Check safety in arching-mechanism (ULS cross-sectional direction)
  36. 36. Steel fibre reinforced UCF Potsdammer Platz Berlijn (1997) In the Netherlands: • Heinoseweg Zwolle (1998) • Betuweroute (1999-2002) • multiple others… 2014: • Mauritshuis (The Hague) • Groninger Forum
  37. 37. Staalvezelversterkt OWB “After-crack-behaviour” à Tensional strength ≈ à Early tensional strength à Tensional strength after crack à Re-distribution of forces à Moment capacity Effect on force distribution tension: bending: à prevents big shrinkage-cracks à limited crack-depth
  38. 38. Moment capacity for UCF with steelfibres à example for UCF with hmin = 700 mm and N’ = 200 kN/m’ à 30 kg/m3 of steelfibres 0 100 200 300 400 0,0 2,0 4,0 6,0 8,0 10,0 momentcapaciteitMRd[kNm/m'] kromming κ [mrad] *10-6 M-N-κ diagram SVB (UGT) C25/30 (UGT) fctd,pl εUGT = 0,1%: MRd = 380 [kNm/m'] Egescheurd = 4.664 [MPa]
  39. 39. Projects Groninger Forum
  40. 40. Projects Groninger Forum
  41. 41. Link to video (dutch) of the process of pooring the UCF with steel fibres for project Groninger Forum: https://vimeo.com/89189883 Lecture CiTG
  42. 42. Projects Mauritshuis (The Hague)
  43. 43. Mauritshuis (The Hague)
  44. 44. Mauritshuis
  45. 45. Link to video (dutch) with animations made by diving company C.O.W.: https://vimeo.com/24826624 Lecture CiTG
  46. 46. Innovations… Traditional building method: - Unreinforced UCF with temporary function - Reinforced concrete floor has permanent function Integrated floordesign: - Steelfibre reinforced UCF - For the permament function the UCF is collaborating with a (traditional) reinforced concrete floor Permanent UCF: - Steelfibre reinforced UCF has a temporary and a permament function
  47. 47. Lecture CiTG 29th of September 2015

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