Lecture CiTG June 4th 2013
Underwater concrete floors
ir. Ruud Arkesteijn
Content
• Use and functions of UCF’s
• Distribut...
Use of UCF’s
Use and functions of UCF’s
Conditions for application in building pits:
1. sub-surface construction…
2. below...
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
Use and functions of UCF’s
1. Water retaining layer
2. Horizontal force equilibrium (strut)
3. Vertical...
Distribution of forces
Distribution of forces
4 mechanisms:
• Boundary-disturbance “Randstoringseffect”
• Arching “Boogwer...
Arching “Boogwerking”
Membrane-effect “Membraanwerking”
Arching & membrane-effect
Re-distribution of forces “Krachtenherverdeling”
Ultimate limit states
1) Bending moments (tension)
2) Bending moments in arch (compression)
3) Shear failure
4) Failure or...
• Longitudinal (“lange richting”):
no boundary-disturbance
normal forces absent
membrane-effect is great!
• Cross-sectiona...
Modelling
Design rules (CUR77)
beam-model of cross-section
Longitudinal:
Serviceability Limit State (SLS)
dry building pit...
Ultimate Limit State (ULS)
structural safety
incl. material and load factors
21
8
d d xM q L
Longitudinal:
no check becaus...
Not in CUR77…
Hydration of concrete produces heat temp. up to 30-45oC
Cooling after heating shrinkage
Strength of concrete...
Case: design of UCF
1. Determine Ly and Lx based on design rule for SLS longitudinal
direction (CUR77) and effective load ...
Staalvezelversterkt OWB
“After-crack-behaviour”
Tensional strength
Early tensional strength
Tensional strength after crack...
Projects
Groninger Forum
Projects
Groninger Forum
Projects
Mauritshuis Den Haag
Mauritshuis Den Haag
Mauritshuis
Lecture CiTG June 4th 2013
= force from strut function
CUR166 results in high value
Verificatie en toepasbaarheid
Normal forces
stempel 'N F N
stempe...
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Presentation for lecture on underwater concrete - TU Delft: MSc Geotechnical Engineering

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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 June 4th 2013 Underwater concrete floors ir. Ruud Arkesteijn Content • Use and functions of UCF’s • Distribution of forces • Design-rules (CUR77) • Steelfibre reinforced UCF’s + • Projects
  2. 2. Use of UCF’s Use and functions of UCF’s Conditions for application in building pits: 1. sub-surface construction… 2. below the groundwater level… 3. in permeable soils. Typical Dutch conditions! Bouwput en fasering
  3. 3. Bouwput en fasering Bouwput en fasering
  4. 4. Bouwput en fasering Bouwput en fasering
  5. 5. Bouwput en fasering Bouwput en fasering
  6. 6. Bouwput en fasering Bouwput en fasering
  7. 7. Functions of UCF’s Use and functions of UCF’s 1. Water retaining layer 2. Horizontal force equilibrium (strut) 3. Vertical force equilibrium (up burst) Or a combination of the above… Bouwput en fasering
  8. 8. Distribution of forces Distribution of forces 4 mechanisms: • Boundary-disturbance “Randstoringseffect” • Arching “Boogwerking” • Membrane-effect “Membraanwerking” • Re-distribution of forces “Krachtenherverdeling” Boundary-disturbance “Randstoringseffect”
  9. 9. Arching “Boogwerking” Membrane-effect “Membraanwerking”
  10. 10. Arching & membrane-effect Re-distribution of forces “Krachtenherverdeling”
  11. 11. Ultimate limit states 1) Bending moments (tension) 2) Bending moments in arch (compression) 3) Shear failure 4) Failure or slipping at retaining wall 5) Pull-out of retaining wall 6) Failure of connection with tension piles (punching shear) 7) Pull-out of tension piles (geotechnical failure) Herziening CUR77 Design rules (CUR77) Design rules (CUR77) CUR77 provides guidelines for design of unreinfoced UCF’s with respect to: • Schematisation • Modelling • Dimensioning • Detailling Demand is to comply with Eurocodes (0, 2 & 7)!
  12. 12. • Longitudinal (“lange richting”): no boundary-disturbance normal forces absent membrane-effect is great! • Cross-sectional (“korte richting”): boundary-disturbance is critical normal forces present (strut-function) limited membrane-effect Assumption: Schematisation #1 Design rules (CUR77) “lange” richting “korte” richting onderwaterbetonvloer damwand palen Ly Lx Ly < Lx tolerances on floor thickness minimal height hgem=800mm ? stresses calculated with hmin Schematisation #2 Design rules (CUR77) Guidelines: tolonder 250 mm for peat/clay 150 mm for sand tolboven 75 mm for hob-dobber higher for slopes?
  13. 13. Modelling Design rules (CUR77) beam-model of cross-section Longitudinal: Serviceability Limit State (SLS) dry building pit discrete cracking (minimal compression-zone) 2 , 1 (zonder N') 8 rep y r repq L M Cross-sectional: uncracked or with arching or with arching + re-dristribution of forces , ,mod , (met N')s rep el s repM M Design rules (CUR77)
  14. 14. Ultimate Limit State (ULS) structural safety incl. material and load factors 21 8 d d xM q L Longitudinal: no check because of membrane-effect Cross sectional: uncracked or with arching and infinite re-distribution of forces (local): Huidige CUR77 , ,mod , (met N' )s d el r d dM M New in revised CUR77 (v2013): 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 5. Safety check for case of UCF slipping at retaining wall 6. Calculation of axial stiffness piles based on secant-value according to CUR236 : Anchor-piles 7. Guidelines for use of 2D calculation models 8. Calculation method for optimization with membrane force Huidige CUR77 Latest developments published in Cement 2013/3
  15. 15. Not in CUR77… Hydration of concrete produces heat temp. up to 30-45oC Cooling after heating shrinkage Strength of concrete at 50% sensitive for cracking Thermal shrinkage of concrete: Huidige CUR77 Verificatie en toepasbaarheid
  16. 16. Case: design of UCF 1. Determine Ly and Lx based on design rule for SLS longitudinal direction (CUR77) and effective load on piles (incl. load factors) 2. Design piles and calculate/estimate axial stiffness piles and walls (CUR2001-4 & CUR77/CUR236) 3. Determine lower boundary normal forces in UCF (D-Sheet Piling) 4. Model cross section of UCF incl. factor of variation (MatrixFrame?) calculate force distribution 5. Check all mechanisms in ULS (no SLS in cross sectional direction!) Huidige CUR77 use CUR77:2001 Steelfibre reinforced UCF Potsdamer Platz Berlijn (1997) In the Netherlands: • Heinoseweg Zwolle (1998) • Betuweroute (1999-2002) • multiple others… Staalvezelversterkt OWB
  17. 17. Staalvezelversterkt OWB “After-crack-behaviour” Tensional strength Early tensional strength Tensional strength after crack Re-distribution of forces Moment capacity Effect on force distribution tension: bending: prevents big shrinkage-cracks limited crack-depth Moment capacity for UCF with steelfibres example for UCF with hmin = 700 mm and N’ = 200 kN/m’ 30 kg/m3 of steelfibres
  18. 18. Projects Groninger Forum Projects Groninger Forum
  19. 19. Projects Mauritshuis Den Haag Mauritshuis Den Haag
  20. 20. Mauritshuis Lecture CiTG June 4th 2013
  21. 21. = force from strut function CUR166 results in high value Verificatie en toepasbaarheid Normal forces stempel 'N F N stempelF 'N = loss of normal force due to friction with piles, walls and soil Smart building pit design: deeper does not lead to thicker UCF raise the water level in pit during excavation removal of upper strut prior to pumping dry? F = additional F due tot membrane effect Starting point: • At first: assume hgem = 1000 mm • Depth of building pit • Design of retaining walls (strut forces) Optimal design process:

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